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Abbott, Dallas

Did a Bolide Impact or a Volcanic Eruption Cause the 535-536 A.D. Climate Catastrophe?

Background: For a period of 18 months in 535-536 A.D., five ancient writers report that the sun was extremely dim. One writer likened it to moonlight.  This dimming of the sun caused catastrophic effects on ancient peoples: famines in Europe, Asia, and Meso-America, mass migration of barbarians into Europe, and epidemics of bubonic plague in Africa, Europe, and Asia.  This dimming of the sun has two possible causes: a massive volcanic eruption in the Java-Sumutra arc or a large bolide impact into the ocean between the Java-Sumatra arc and Australia.  There is bathymetric evidence for a tremendous pre-1883 eruption of the volcano Krakatau that dwarfs the catastrophic 1883 eruption of that same volcano. This earlier eruption is not well dated.  There is also evidence for tsunami runups of over 100 meters from a bolide impact (or a large submarine landslide) between Australia and the Java-Sumatra arc.

Volcanic ash layers and bolide ejecta layers both have a high magnetic susceptibility.  Typical carbonate-rich marine sediments have an extremely low magnetic susceptibility.  This project would involve measuring magnetic susceptibility on the upper two meters of LDEO cores from the seafloor between the Java-Sumatra arc and Australia.  We will preferentially select cores known to contain the Toba ash layer, which formed 75,000 years ago.  After sieving the high susceptibility layers, we will examine the coarse fraction for impact spherules and volcanic glass. Using a combination of C-14 age dates on microfossils and ⁴⁰Ar/³⁹Ar age dates on volcanic glass, we will date the ash layers and/or impact layers. Finally, we will map the thickness and chemistry of ash layers to determine their probable source volcano.

Required Work: The project will require about 8-12-hours of lab work during the semester and 40 hours per week during the summer. Lab work includes measurements of magnetic susceptibility, wet sieving, scanning electron microscope work and microprobe work.

Prerequisites: None. Student should enjoy microscope and laboratory work.

Suggested Reading: Catastrophe! by David Keays, Night Comes to the Cretaceous by James Lawrence Powell and Catastrophic Encounters with Comets by Mike Baillie

Thesis Mentor Information: Dallas Abbott (Marine geology and geophysics, Impact craters, Precambrian geology) dallas@ldeo.columbia.edu Tel: 845-365-8664

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Abbott, Dallas

What is the Distribution of Tsunami Runups from the Mahuika Bolide Impact?

Background: Less than 1000 years ago, a 1 km bolide hit the southern New Zealand continental shelf, producing the 20 km-Mahuika impact crater. This event has possible links to widespread wildfires in New Zealand, coastal abandonment by the Maori people, and tsunami runups of over 130 meters in Jervis Bay, Australia, all around 1400-1500 A.D. Because the crater is located in 300 meters of water, the starting tsunami wave height was about 300 meters. At Stewart Island, the southernmost island of New Zealand, the tsunami was about 20 meters high, potentially producing maximum runups onto land of 200 meters. The west coast of Stewart Island contains previously enigmatic sand lobes that extend from the beach to the east. Some sand lobes extend to 200 meters above sea level.  Others extend over 4.2 km inland.  These sand lobes may represent deposits of beach sand that were transported inland by the tsunami from the Mahuika crater. Alternatively, they might represent windblown sand. 

Required Work: The project would involve 3 parts. Part 1 would involve sieving of samples from the sand lobes collected during our February 2004 field expedition to the central part of western Stewart Island.  The goal would be to look for coarse grained, unsorted material within the sand layers. If we find this material, it will constitute important evidence that the sand layers were deposited by a tsunami. We will then proceed to parts 2 and. 3. Part 2 would involve looking for more sand lobe deposits on aerial photos of the northern and southern parts of western Stewart Island, and the southwestern portion of the South Island of New Zealand. Using topographic maps superimposed on the aerial photos, the student will estimate the maximum height above sea level and the maximum inland penetration distance of the tsunami deposits.  These numbers will be very useful for calibrating models of tsunami runup and for estimating the hazard to society of impact-generated tsunamis. Contingent upon funding, the student would then participate part 3:  This would involve a field expedition to New Zealand in the winter of 2004-2005. The goal of the field expedition would be to ground truth the estimates of tsunami runup and inland penetration derived from the aerial photos and topographic maps. The project will require about 8-12-hours of lab work during the semester and 40 hours per week during the summer. Lab work will include: measurements of magnetic susceptibility, wet sieving, scanning electron microscope work and microprobe work.

Prerequisites: None. Student should enjoy laboratory and computer work.

Suggested Reading: Night Comes to the Cretaceous by James Lawrence Powell and Tsunami: The Underrated Hazard by Edward Bryant.

Thesis Mentor Information: Dallas Abbott (Marine geology and geophysics, Impact craters, Precambrian geology) dallas@ldeo.columbia.edu Tel: 845-365-8664

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Abbott, Dallas

What is the True Rate of Recurrence of Large Bolide Impacts?

Background: Using standard rates of estimates of recurrence of large bolide impacts, a 1 km bolide impact occurs every 1 million years. However we have discovered an impact crater that was produced by a 1 km bolide that is less than 1000 years old.  We have also learned of an impact layer in the Ross Sea that has impact spherules large enough to be produced by a 2 km bolide (source crater ~60 km in diameter).  This impact event occurred less than 27,000 years ago.  We have also discovered 2 other impact craters, one 132 km in diameter and another 150 km in diameter. Standard estimates of recurrence rates for craters this size are about 40 million years and 65 million years, respectively.  However, the 132 km crater is about 2.5 million years old and the 150 km crater is about 7 to 11 million years old.  These results, although preliminary, suggest that the standard methods of estimating impact recurrence rate are vastly underestimating the true impact rate. We suspect that the standard methods are wrong because they ignore the impact hazard from comets. Because even a 1-km bolide impact could have catastrophic effects on human civilization, it is important to understand how often large impactors hit the Earth.

Because impact layers have a high magnetic susceptibility, magnetic susceptibility is the ideal tool to use. This project would search for impact layers in deep-sea cores. The goal would be to characterize the impact rate of large impactors (>60 km), those that produce impact spherules large than 100 microns.  This size of impact spherule is relatively easy to work with.

Required Work: The student would perform along core measurements of magnetic susceptibility on red clay sediments, which accumulate at a rate of 1 meter per million years. We will use ⁴⁰Ar/³⁹Ar dating of impact spherules with high K contents to provide ages.  The student will confirm the radiometric ages by using magnetic susceptibility to find the impact layer within carbonate-rich cores. These accumulate at a much higher rate of about 100 to 300 meters per million years and have good biostratigraphic age estimates.  Using these well-dated layers, the PI will help the student to use spherule sizes and compositions to estimate the location of the impact (land or ocean) and the size of the source impact crater.  The results will provide better estimates of the overall recurrence rate of and hazard from impact events.

Prerequisites: None. Student should enjoy laboratory work and microscope work.

Suggested Reading: Night Comes to the Cretaceous by James Lawrence Powell and Catastrophic Encounters with Comets by Mike Baillie

Thesis Mentor Information: Dallas Abbott (Marine geology and geophysics, Impact craters, Precambrian geology) dallas@ldeo.columbia.edu Tel: 845-365-8664

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Anderson, Bob

Do diatoms in the glacial Southern Ocean (Antarctica) provide a clue about climate-related changes in the global carbon cycle?

Background: Processes in the ocean around Antarctica are important in regulating ocean circulation, ocean chemistry, and the global carbon cycle.  These processes are believed both to be sensitive to climate change and to influence climate change.  Environmental conditions in the Southern Ocean are "recorded" by the species of diatoms (phytoplankton, or microscopic alga) that live in the ocean.  Climate conditions also influence the abundance of diatoms that live in the Southern Ocean and this, in turn, may have significant impacts on the global ocean cycles of carbon and nutrients.  We seek to reconstruct from sediment records the changes in diatom abundance in the Pacific sector of the Southern Ocean between the peak of the last Ice Age (approximately 18,000 to 26,000 years before present) and the Holocene (the warm climate of the past 12,000 years).  The student intern(s) will help survey and select sediment cores for study.  Students will be trained to process samples from selected cores, identify key diatom species, and construct records of diatom abundance in sediments that reveal information both about the age of the sediments, and the environmental conditions that existed at the time the sediments were deposited.  Once the age of the sediment records has been established, students will use geochemical methods to determine the rate at which opal (diatom shells) accumulated in the sediments.  The immediate objective is to determine if diatoms were more or less abundant during the ice age than at present.  It is anticipated that 2 students will work as a team on this project.  Students will work both with a microscope and in a chemistry lab, and will have an opportunity to learn about climate-related changes in ocean ecology, and about how the ocean regulates the amount of carbon dioxide (greenhouse gas) in the atmosphere. 

Required Work: Students will be exposed to a variety of lab work, including the survey of sediment cores, microscope work, and wet chemistry.  These activities constitute most of the students’ efforts. 

Pre-requisites: Prefer some college chemistry lab experience and/or lab experience in earth science. 

Thesis Mentor Information: Dr. Bob Anderson (Marine geochemistry; paleoceanography), boba@ldeo.columbia.edu, Tel. 845-365-8508

Dr. Lloyd Burckle (Marine micropaleontology, paleoceanography), burckle@ldeo.olumbia.edu.  Tel.  845-365-8406

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Cheng, Zhongqu (Joshua)

Exploratory study of arsenic in tree rings at a superfund site

Background:  Tree rings are known to be a useful tool for studying past climate change.  Elemental concentrations in dated tree rings, or the “dendrochemistry”, can provide a temporal record of environmental change.  Little is known about arsenic in trees, not to mention the potential of tree rings as a biological monitor for past arsenic pollution.  Dead and growing trees at a former pesticide-manufacturing site, now an EPA superfund site being cleaned up, offers an opportunity to study how the levels of arsenic in annual tree rings have responded to this localized but severe contamination. 

The current project, supported by a Climate Center small fund, will explore the possibility to study arsenic in tree rings at the Vineland superfund site in southern New Jersey.  Tree species at and around the site will be surveyed, and non-destructive increment coring will be obtained from breast height of a selected number of living trees.  Dead stems of different heights will be collected using a chainsaw.  Preparation of coring for cross-dating and growth analysis will be performed at the tree-ring lab.  Plant material (dissected annual rings) from 4-5 increment coring will be digested and analyzed at the core laboratory with a newly furnished HR ICP-MS equipment, for As and a suite of other major and trace elements (Na, Mg, Al, Si, P, K, Ca, Mg, Mn, Fe, Li, Pb, Ba, Sr).  Soil and pore water samples for these cores will also be collected and analyzed.  In addition, a few leaf and bark samples will also be collected for analysis and to compare with the ring concentrations. 

The As concentrations of tree rings will be compared to surrounding area and background values to evaluate the environmental stress from arsenic.  The radial distribution of arsenic will be compared to the radial patterns of other elements, the growth pattern, the climatic record, the hydrologic change, the contamination history, relative location and distance to the plume, soil and pore water concentrations.  Cores of different directions and variability between trees will be examined.  It will also be interesting to see if there is any effect of arsenic intoxication on the uptake of other important minerals.  The cause of death for a large number of trees at the site is to be investigated – does it have something to do with environmental stress from arsenic?

Required Work: The student is expected to work with me and Dr. Brendan Buckley of the Tree Ring Lab (Lamont) on various aspect of this work in the summer.  Possible tasks, depending on interest level, will be field examination of trees, field coring and lab dissection of rings, assistance in growth analysis and chemical analysis, data processing reporting, and publication depending on progress. Workloads are expected to be 4-5 days (28-35 hours) a week.

Pre-requisites: some chemistry knowledge, interest in environmental studies.

Thesis Mentor Information: Dr. Zhongqi (Joshua) Cheng (New Core Lab), czhongqi@ldeo.columbia.edu, Tel. 845-365-8649

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Franzese, Allison

Grain size distribution of South Atlantic sediments and their implications for paleo-circulation.

Background: The grain size distribution of a sediment sample depends on 2 primary factors (1) the grain size distribution of the source and (2) size sorting during transport.  This project would use the grain size distributions of sediments from deep-sea cores in the eastern South Atlantic Ocean, and the Atlantic sector of the Southern Ocean to compare the ocean circulation patterns that existed during the Last Glacial Maximum (~20,000 years ago) with those that exist today.  A possible extension to this project would be to analyze the compositions of the different grain size fractions.  This would allow us to better characterize the sediment sources and better understand the sedimentation processes both today, and in the past.

Required Work: Lab work would include wet sieving of sediments, chemical leaching, weighing, settling, and centrifuging.  (This project could be expanded to include chemical digestions and separations and mass spectrometry) Data analysis will be done using Microsoft Excel.

Hours per week spent in the lab can be decided with the student.  (The project’s focus will be altered accordingly)

Pre-requisites: Some background in geology. A little bit of some common sense, some patience and a willingness to learn are useful, but not required. Some knowledge of sedimentology or ocean circulation (More knowledge means less background reading.) 

Some laboratory experience (either as independent research or as part of a course.)

Thesis Mentor Information: Allison Franzese (Geochemistry), franzese@ldeo.columbia.edu, Tel. 845-365-8661;  (Sidney Hemming (Geochemistry), sidney@ldeo.columbia.edu, Tel. 845-365-8417)

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Convection in the Indian Ocean: dynamical links to the

Asian and African summer monsoons

Background: The patterns of interannual variability of rainfall in the northern hemisphere summer monsoon regions of Asia and Africa hint at interesting connections, between the continental regions of Asia and Africa, and with the tropical Indian Ocean.

The societal relevance to understanding the 'vagaries' of the monsoons cannot be overstated. The failure of the Indian monsoon in the summer of 2002 took everyone by surprise. The all-India summer monsoon rainfall index fell 20% below the climatological average, forcing the government to intervene with hundreds of thousands of dollars in relief to the agricultural sector (IRI Climate Information Digest, August 2002 issue; http://iri.columbia.edu/climate/cid/Aug2002/). The repeated recurrence of drought in the African Sahel -the semi-arid region immediately to the south of the Sahara desert- from the late 1960s to the 1980s, changed the landscape of the region, and culminated in the establishment of the UN Convention to Combat Desertification (http://www.unccd.int/main.php)

Recent research towards an explanation for these occurrences points to the tropical Indian Ocean.  Deep convection in tropical regions is the engine of atmospheric variability. Acting as a source of energy for the atmosphere, convection drives the large-scale atmospheric circulation, potentially affecting regions far removed from the source location itself (think of El Nino and its impact on weather along the west coast of the U.S.).  The goal of this project is to identify the dynamical connections between atmospheric convection and precipitation in the tropical Indian Ocean and precipitation over the adjacent continental regions, on seasonal and shorter time scales.

Pre-requisites: basic knowledge of statistical analysis. Knowledge of some meteorology a plus.

Thesis Mentor Information: Alessandra Giannini, alesall@iri.columbia.edu

Tel: (845)680-4473

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Hays, Jim

Estimating changes in radiolarian depth habitat in the North Atlantic between glacial and interglacial times

Background: The Radiolaria (a shell bearing one single celled planktonic animal) C. davisiana and several less abundant Radiolaria are the only planktonic species with a fossil record known to live a mid-water depths (>300m). They depend on carbon ultimately derived for surface water primary productivity. There abundance variations, therefore, can be a measure of carbon flux or "export" from surface-water to deep-water. This export can affect atmospheric CO₂ concentrations and thus climate. The greater abundance of C. davisiana in glacial than in interglacial high latitude deep-sea sediments suggest there was greater carbon export at this time. We know that atmospheric CO₂ concentrations in the glacial atmosphere were lower than in the present atmosphere. The unanswered question is what is the cause of the lowered CO₂ concentrations in the Earth's atmosphere in glacial times compared to today? Can the abundance changes of C. davisiana in North Atlantic deep-sea sediments shed some light on this?

Our preliminary (low-resolution) studies of Radiolaria in high-latitude North Atlantic sediments have shown that the abundance variations of the species, Cycladophora davisiana, are similar to those recorded in late Pleistocene/Holocene sequences from the Antarctic, Bering Sea and North Pacific (Hays et al., 1976; Morley, 1983; Morley et al., 1982; Morley and Robinson, 1986).  Recent studies (Hays and Morley, 2003) have shown that high abundances of this species are associated with specific hydrographic and biological structures similar to those present in the modern Okhotsk Sea; specifically very cold, low salinity, stable surface waters, limited depth of mixing of surface waters and extensive winter sea ice, all of which contribute to a reduction of high-latitude surface-water nutrients and a reduction in atmospheric carbon dioxide.  Based on these recent results, we are constructing high-resolution C. davisiana records with stratigraphic control from high-latitude oceans to examine the precise timing of this species' abundance variations with changes in global ice volume and high-latitude surface water properties.

Required Work: We have selected two North Atlantic cores for this study, to compare the timing and amount of C. davisiana abundance changes here with other parts of the world. We will teach the selected intern to sample deep-sea cores, separate Radiolaria for these sediment samples and prepare microscope slides. Using a microscope we will teach the student to identify Radiolaria in general and the species C. davisiana in particular. Both of the selected cores have been previously sampled and a preliminary C. davisiana record produced.  In core V27-20 (our most northwestern core), it is necessary to increase our sampling interval from 20 to 5-cm intervals in the upper 2m (record of the last 35,000 years) and through the last interglacial (from 20 to 10-cm intervals) when global climate conditions were similar to today's.  In the other core (V17-114, with a very high sedimentation rate), we propose increasing the C. davisiana resolution from 20 to 10-cm intervals beginning at about 2m in the core (~10Kyr) and continuing throughout the 11m core which will provide a record extending nearly through the entire last interglacial. 

Comparison of the two North Atlantic high-resolution C. davisiana curves with discontinous oxygen isotope values and other biostratigraphic markers will assist in determining whether abundance variations of this radiolarian species are synchronous across the high-latitude North Atlantic or responding to more local changes in ecological conditions.  The intern will then compare the timing of C. davisiana abundance changes in the two North Atlantic sites, with high-resolution records already generated from the Bering Sea and Antarctic.

Prerequisites: None

Thesis Mentor Information: Jim Hays, jimhays@ldeo.columbia.edu

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Houghton, Bob

Understanding the wind-driven dispersion of a coastal river plume.

Background: The year 2004 will be the second year of an NSF funded study (with co-PI’s from U. Delaware and U. Georgia) of the dispersion of the Delaware River plume forced by up- and downwelling favorable winds east of Cape Henlopen. Last year’s cruise was a spectacular success providing useful data to test model predictions and to plan for the more extensive field program in 2004. Two cruises are scheduled: April 15-20 and May 13-18. A dye tracer will be injected into the river plume and its dispersion will be mapped using a Scanfish, a towed ‘flying’ ocean vehicle. A great deal of other oceanic data will be collected concurrently.

Required Work: The summer project will involve analysis of the resulting data set. It will be a large, rich data set that can be subdivided for various topics suitable for a 2-month study. Participation in a cruise is not required or expected although it would be interesting and instructive.

Prerequisites: Experience with computers in general and MatLab in particular is useful. Willingness to learn about coastal physical oceanography is essential.

Thesis Mentor Information: Bob Houghton, Houghton@ldeo.columbia.edu

Tel: 845-365-8328

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Ho, David

Study of water movement in rivers and estuaries

Background: This summer, we plan to conduct two SF₆ tracer release experiments: one in the tidal Hudson River and another in the Hackensack River to examine transport and mixing processes. The mixing and transport of contaminants in the waterways of a large urban estuary has many environmental and management implications. The pathways taken by accidental or deliberate discharges of pollutants, determine their spatial and temporal distribution.  These transport processes also play an important role in governing the cycling of biogeochemical trace gases (e.g., CO₂ and N₂O).  In the past two years, we have conducted three SF₆ tracer release experiment in the Hudson River Estuary, two in the tidal Hudson River near Newburgh and Hyde Park, the upper Hudson River, in New York Harbor, and in the East River/Long Island Sound to examine advection, dispersion, and air-water gas exchange.  For more information on those experiments, see <http://www.seas.columbia.edu/earth/tracer/>.

Required Work: Specific tasks will include preparation of equipment for field work, participation in data collection in the field, and evaluation of the data collected in the Hudson Estuary in the context of mixing and spreading of contaminants in the waterways around New York City.

Pre-requisites: College level chemistry.

Thesis Mentor Information: David Ho (Geochemistry), david@ldeo.columbia.edu, Tel. 845-365-8706

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Ho, David

An analytical system for a rapid analysis of SF₆ and CFCs in seawater

Background: Emissions of trace gases with little or virtually no natural background by human activities have been used successfully in studies of the circulation in the oceans, as well as in continental surface waters. In principle these trace substances are used as global ‘dyes’ that penetrate from the surface of the oceans or a continental water body into the interior. The penetration process is being imaged by (repeated) surveys (2- or 3-dimensional).

One precondition for utilization of these tracers is development of techniques that allow (semi)-automated measurement of the tracers at high sampling rates at sea. This project is aimed at building a new analytical capability for simultaneous measurement of CFCs and SF₆ for studies of ocean circulation in the framework of a recently funded NSF project. The main goal of the project is the design, construction and test (at sea) of this new instrumentation.

Required Work: The student would learn how to build new analytical equipment including its computer control. Additionally, the student would be familiarized with using environmental tracers in studies of ocean circulation and circulation of continental surface waters.  The project will also include building parts of the equipment and testing of equipment in the laboratory, as well as evaluating the data collected with the new system. The student would work in the Environmental Tracer Group with David Ho, Bill Smethie and Peter Schlosser.

Pre-requisites: College level chemistry and physics; interest in, and/or experience with analytical instruments

Thesis Mentor Information: David Ho (Geochemistry), david@ldeo.columbia.edu, Tel. 845-365-8706

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Ho, David

Analysis of atmospheric trace gases chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF₆) near New York City

 Background: CFCs are anthropogenic compounds that were historically used as refrigerants, foam blowing agents, and propellants. Their production was regulated by the Montreal Protocol due to their impact on stratospheric ozone. Current releases are primarily from older refrigeration units.  SF₆, like the CFCs, is a chemical compound with a predominantly anthropogenic source.  Its primary use is as an electrical insulator in high voltage switching gear.  While a potent greenhouse gas, it has not been significantly regulated and its concentration is still increasing rapidly in the atmosphere.  For environmental scientist, local and regional emissions of SF₆ and CFCs are of interest for studying their impact on the use of these gases as groundwater-dating tool near source regions, as well as for quantifying the contribution of these environmentally relevant gases, from a local region to the global atmosphere.  Scientists at Lamont-Doherty Earth Observatory (LDEO) are currently working on quantifying the spatial and temporal patterns of CFCs and SF₆ concentrations in and around NYC in order to document the sources and transport of these gases. The spreading of CFCs and SF₆ in urban settings can also be used to infer information on spreading patterns of airborne pollutants.

Required Work: This project will allow the student to participate in collection and analysis of data that deal with spreading of atmospheric trace gases, as well as its variability. The analysis will put the data into the context of the general topic of application of tracers to environmental problems, both in terms of studies of groundwater flow and atmospheric spreading patterns around urban centers.

The specific tasks would include compilation and statistical analysis of atmospheric CFCs and SF₆ time series measured at LDEO, as well as meteorological data from the same time period. The student will also assist in collection and analysis of gas samples from NYC area locations. The student may also undertake an evaluation of SF₆ emissions data for NYC and compare this data to observations using a simple atmospheric model.

Prerequisites: Computers skills, basic statistics.

Thesis Mentor Information: David Ho (Geochemistry), david@ldeo.columbia.edu, Tel. 845-365-8706

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Jones, Ian. S. F.

Ocean productivity website

Background: Ocean Nourishment is a new technology to increase the sequestration of carbon in the ocean and to increase the productivity of the ocean to make capture fisheries sustainable. This technology is suitable for Low-Income Food Deficient (LIFD) countries as it can generate income from carbon credits and provide economical protein in the EEZ of developing country.  It relies on providing the nutrients to the upper sun lit ocean that limit the growth of phytoplankton.

Project: To develop a modeling tool to allow people from LIFD countries, through the world wide web, to be able to envisage the increase in primary production possible by ocean nourishment and to use an empirical relation between sustainable fish catch and primary production to speculate on the impact on fish catch.

Required Work: The project involves constructing a web site, creating the software to find ocean color satellite images from the data base, then using published modeling work to contrast the chlorophyll level under an Ocean Nourishment regime with the present situation as revealed by satellite and finally publishing the result on the web.

 

Pre-requisites: Two years of geoscience or environmental engineering

 

Thesis Mentor Information: Dr Ian S F Jones. Isj7@columbia.edu

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Kaplan, Alexey

 

Small-scale and short-term variability in sea level height and ocean surface winds

 

Background: Despite great differences in complexity, all tropical Pacific sea level height simulation and assimilation products that we have analyzed to date have similar error patterns. The common features can be traced to the spatial energy distribution in the small-scale and short-term variability of ocean sea level. Inadequate simulation of this variability, which to a large extent can be attributed to likewise variability in surface winds, contributes to one of the major problems of existing Global Climate Models (GCMs): systematic underestimation of signal variance. Therefore we focus on the study of these types of variability, their causes, and ways to account for them in various oceanographic applications.

 

Small-scale and short-term variability plays a major role in the errors of observational and model data sets.  We will pursue 4 specific objectives: (1) study of dynamical nature and statistical properties of the small-scale and short-term variability in sea level height and surface winds (using TOPEX, Jason, NSCAT, QuikSCAT); (2) developing statistical descriptions of these types of variability suitable for the use in data assimilation procedures; (3) specifying the nature of numerical model errors on such scales.

 

Required Work: A study of the spatial and temporal correlations of the small-scale and short-term variability in global sea level height and surface wind fields and their dynamical connection. Data from satellite missions Topex/Poseidon, Jason, and ERS-1,2, NSCAT, and QuikSCAT will be used.  Random forcing errors of various statistical characteristics will be generated to drive a linear model and to study its variability in response.  Based on this analysis, a description of the small-scale and short-term variability suitable for error modeling has to be produced. Case studies of areas with high error growth (Gulf Stream, Aguhlas Current, North Equatorial Countercurrent) comparing model analyses with satellite data there will be used as a starting point.

 

Pre-requisites: Calculus, statistics, computer programming. A candidate shouldn't be scared by the prospect of dealing with large data sets.

 

Thesis Mentor Information: Alexey Kaplan (LDEO),

alexeyk@ldeo.columbia.edu, Tel: (845) 365-8689

 

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Kaplan, Alexey

 

El Nino events of the 19-20th centuries: Historical evidence versus instrumental data

 

Background: El Nino events (episodes of anomalously warm sea surface temperatures in the eastern tropical Pacific) are recognized to influence dramatically the tropical weather and generally to have worldwide climatic impacts. Because of that the chronologies of the El Nino events for the last few centuries were compiled on the basis of their manifestations on the land and particularly coastal regions (droughts, floods, famines, yellow fever outbreaks, episodes of mass mortality of endemic marine organisms and guano birds, changes in travel times of the sailing ships, affects on coastal fisheries, etc), despite the instrumental measurements of climatic variables were very sparse prior to 1950s. Interpretation of historical evidence, reconciling it with some paleoclimatic sources (like tree-ring width chronologies), and assigning appropriate strength ratings to the individual El Nino events are the subject of the ongoing scientific debate. At the same time extensive compilations of instrumental marine and land-based climate data from 1800s on have recently become available, and based on them near-global climate reconstructions have been developed in the LDEO. The goal of this project is to use these new sources of information to ground-truth the ratings of El Nino events based on the historical evidence and to reconcile the information from different sources, or to explain the differences.

 

Required Work: Receiving, comparing, analyzing climatic data from different sources. Computer work will involve downloading the data, producing plots, using statistical tools. Depending on the student's natural inclination, the project may go into deeper library research mode (tracking the original sources on which the historical ratings of the El Nino events were based and re-examining the evidence) or into more sophisticated mathematical/statistical analysis, but some elements of both will necessarily be present.

 

Prerequisites: Not really prerequisites, but rather a list of skills/inclinations each of which can be used for an advantage in this project (none are mandatory): fluent reading in foreign languages (particularly Spanish, but other languages are useful as well), math/statistical background, computer programming experience, interest/background in climate of any particular region or climate impacts.

 

Thesis Mentor Information: Alexey Kaplan (LDEO),

alexeyk@ldeo.columbia.edu, Tel: (845) 365-8689

 

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Kilpatrick, Marm

 

Risk of West Nile virus for humans: A field study

 

Background: West Nile virus is the most important arbovirus in North America with over 10,000 cases and 400 deaths in the past two years.  Birds primarily carry the disease, and human cases are the result of a spillover event when a bird-biting mosquito bites a human or a mosquito with a broader diet bites an infectious bird and then bites a human.  Spatial variation of West Nile virus cases are poorly understood and are likely an overlap between infection levels in birds, mosquito densities and human behavior.  The CCM has a field project testing several hypotheses about what drives variation in West Nile virus prevalence in birds and mosquitoes, and therefore, what influences risk for human cases.  The internship will help collect data from the field by capturing birds and taking blood samples, and capturing and identifying mosquitoes at 8-10 sites in NY or DC.

 

Location:  Rockland County, New York, & Washington D.C.

 

Required Work: The intern will be expected to remove birds from mist-nets, measure and band birds and take blood samples for West Nile virus testing.  The intern will also assist in mosquito trapping and identification. Intern will join a large project looking at all aspects of West Nile virus, including local determinants, climate and host reservoir competence laboratory studies.  Research environment provides exposure to a broad array of research projects.

 

Prerequisites: None required.  All training will be provided.

 

Thesis Mentor Information: Dr Marm Kilpatrick, Consortium for Conservation Medicine, Palisades NY and CERC (kilpatrick@conservationmedicine.org). (845) 365-8373, Dr Peter Daszak, Consortium for Conservation Medicine, Palisades NY and CERC (daszak@conservationmedicine.org)

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Kilpatrick, Marm

 

Impacts of West Nile virus on survival and reproduction: a field study

Location:  Rockland County, New York

 

Background: West Nile virus is the most important arbovirus in North America with over 10,000 cases and 400 deaths in the past two years.  Birds primarily carry the disease, and human cases are the result of a spillover event when a bird-biting mosquito bites a human or a mosquito with a broader diet bites an infectious bird and then bites a human.  Spatial variation of West Nile virus cases are poorly understood and are likely an overlap between infection levels in birds, mosquito densities and human behavior.  The CCM has a field project examining the effect of West Nile virus infection on the survival and reproduction of the breeding bird community.  The internship will direct efforts to collect survival and reproductive data for several species at 8-10 sites in NY.

 

Required Work: The intern will lead a project nest searching, nest monitoring and performing a mark-recapture experiment to estimate survival of color banded birds that have been tested for exposure to West Nile virus. Intern will join large project looking at all aspects of West Nile virus, including local determinants, climate and host reservoir competence laboratory studies.  Research environment provides exposure to a broad array of research projects.

 

Special Qualifications:  None required.  All training will be provided.

 

Thesis Mentor Information: Dr Marm Kilpatrick, Consortium for Conservation Medicine, Palisades NY and CERC (kilpatrick@conservationmedicine.org). (845) 365-8373, Dr Peter Daszak, Consortium for Conservation Medicine, Palisades NY and CERC (daszak@conservationmedicine.org)

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Kim, Won-Young

 

Accurate Location of Earthquakes and Structure of the Devonian Meteor Impact Crater in the Charlevoix Seismic Zone, St. Lawrence River, Canada

 

Background: The Charlevoix seismic zone is located along the St. Lawrence River about 100 km northeast of Quebec City, Canada.  It is one of the most active seismic zones in eastern North America.  The Charlevoix area, which is host to an impact structure of Devonian age, straddles the boundaries among crystalline rocks of the Grenville Province, the Cambrian-Ordovician sedimentary succession of the St. Lawrence Platform, and accreted units of the Appalachian orogen.  The fault systems in the Charlevoix area are interpreted to be pre-impact structures related to the opening of the Iapetus Ocean, most of which have also been reactivated during the Devonian cratering event and in post-impact time, the latter most likely with the Atlantic Ocean rifting in Mesozoic time.  Tomographic studies of seismic velocities in the region suggested that high velocity is associated with the center of the impact crater, where less earthquakes occurred than surrounding low velocity, highly disrupted rocks.  So far, earthquakes are not very well located and hence, it would be very useful to apply recently developed high-resolution earthquake location methods such as double-difference technique to relocate the earthquakes in the Charlevoix seismic zone.  Accurate earthquake locations will provide us with better understanding of nature of the seismogenic faults in the Charlevoix seismic zone.

 

Field work: Visit seismographic stations in the Adirondacks and Lake Champlain area for LCSN station service, ~ 2 nights & 3 days.  Station visit can be extended to visit Charlevoix Seismic Zone in Quebec, Canada, ~1 night & 2 days.

 

Required Work: Assemble seismic bulletin and waveform data for earthquake relocation.  Perform waveform cross- and auto-correlation, and pick P- and S-wave arrival times.  Locate earthquakes using double-difference technique. Approximately 8 hours / week would be needed during the semester.

 

Pre-requisites: College level physics background.  Experience on UNIX workstations is desirable but not necessary. 

 

Thesis Mentor Information: Won-Young Kim, wykim@ldeo.columbia.edu

Phone: (845) 365-8387

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Comparative Study of 1D Seismic Velocity Models Underneath Manhattan Prong, Newark Basin and Reading Prong from Teleseismic Receiver Function Analysis

 

 

Background: In the past five years, the Lamont-Doherty Cooperative Seismographic Network (LCSN) which monitors earthquakes in the northeastern United States installed high-quality, three-component, broadband seismographs at several site in the region.  These sites are in diverse geologic environments. Two stations -- Central Park, Manhattan (CPNY) and Fordham University in the Bronx (FOR), are situated in the Manhattan Prong on old Precambrian bedrock, the station BRNJ (Basking Ridge, New Jersey) is in the Mesozoic Newark Basin, and two stations -- Lehigh, Penn (LUPA) and Millersville, Penn (MVL), are in Reading Prong.  In the late 1990's, scientists at Lamont found that the shear waves arriving at the seismographic stations in the northeastern US showed substantial variation depending upon the azimuth of the incoming phase and that the shear-wave splitting pattern provided constraints on anisotropic properties of the crust and uppermost mantle.  The data from the new stations are original material suitable for developing 1D-velocity models underneath each station using teleseismic receiver function analysis.  The results will be very useful, because there were no broadband digital seismographs in these diverse geologic environments in the past.

 

Field work: Visit seismographic stations mentioned in the short description to learn about seismic instrumentation, earthquake monitoring and geology around each station. The work includes 3 day-long trips to 1) Manhattan & the Bronx; 2) Basking Ridge, New Jersey and Lehigh, Pennsylvania and 3) Millersville, Pennsylvania.

 

Required Work: Assemble teleseismic earthquake waveform data for each station and for many azimuths. Perform waveform data processing, learn filtering, determine spectral characteristics and noise and rotate into radial-transverse components, and other standard tools. Calculate receiver functions, stacking signals to improve signal-to-noise ratio, inverting for 1D velocity structure. Interpret the results. Approximately 8 hours / week would be needed.

 

Pre-requisites: College level physics background.  Experience on UNIX workstations is desirable but not necessary. 

 

Thesis Mentor Information: Won-Young Kim, wykim@ldeo.columbia.edu

Phone: (845) 365-8387

 

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Kujawinski, Elizabeth

 

Examining the role of protozoan grazers in estuarine and marine organic carbon cycles.

 

Background: Although the role of the microbial web in organic matter (OM) cycling in the coastal and open ocean has been well-established, molecular-level understanding of the transformations within different pools of OM has not been possible due to analytical limitations.  The study proposed here will examine these transformations using isotope-ratio gas chromatography / mass spectrometry (irGC/MS) and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS).  Laboratory cultures of protozoa, bacteria and/or phytoplankton will be monitored for changes in OM composition as a function of time.  The prey cultures will be isotopically-labeled with either C13-acetate (bacterial prey) or C13-bicarbonate (phytoplankton prey).  Incorporation of the C13-label from prey material will be tracked through the protozoan digestive process and the lability of different OM fractions within grazing cultures can be estimated.  Laboratory results will be extended to the field with incubations of size-fractionated seawater from coastal (NY) and oligotrophic (Bermuda) environments.

 

Required Work: In the summer, approximately 30hrs / wk; Semester: 6-10 hrs/ week (undergraduate); 10-20 hrs/ week (graduate).

 

Pre-requisites:  At least two semesters of chemistry (at least one semester each of general chemistry and organic chemistry is preferred); at least one semester of biology.

 

Thesis Mentor Information: Elizabeth Kujawinski (Barnard Environmental Science); ekujawin@barnard.edu,  (212) 854-7956

 

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Kujawinski, Elizabeth

 

Coupling the presence of microorganisms to their role in the transformations of organic matter in subsurface environments

 

Background: The carbon cycle in aquifer systems is poorly understood.  In particular, the role of prokaryotic and eukaryotic microbes in the cycling of organic matter (OM) has not been well documented.  The goal of this work is to utilize stable isotopes in combination with geochemical and microbial methods to study microbially-mediated OM transformations in aquifers and aquifer sediments.  This work will use isotopically labeled compounds, 13C-acetate and 15N-ammonia, to track the active microbial community and its effect on molecular-level changes in OM.  DNA, RNA, and relevant biomarkers will be isolated in laboratory sediment-core experiments.  The labeled nucleic acids will be separated from non-labeled nucleic acids by ultra-centrifugation.  The labeled nucleic acids will be sequenced to determine the composition of the actively respiring microbial consortia.  In parallel, the OM will be analyzed by isotope ratio gas chromatography / mass spectrometry (irGC-MS) and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS).  The incorporation of 13C and 15N will allow us to estimate residence times of different OM fractions and to answer fundamental questions about OM lability in the subsurface environment.

 

Required Work: In the summer, approximately 30hrs / wk; Semester: 6-10 hrs/ week (undergraduate); 10-20 hrs/ week (graduate).

 

Pre-requisites:  At least two semesters of chemistry (at least one semester each of general chemistry and organic chemistry is preferred); at least one semester of biology (molecular biology experience a plus).

 

Thesis Mentor Information: Elizabeth Kujawinski (Barnard Environmental Science); ekujawin@barnard.edu,  (212) 854-7956, and Brian Mailloux (Columbia Earth Institute Postdoctoral Fellow), bjm2103@columbia.edu

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Lackner, Klaus

 

Analyze impact of carbon-constraining policies on synthetic crude oil production from Canadian tar sands 

Background: Canada’s oil reserves have recently been upgraded by including the hereto-ignored tar sand reserves.  This revision in the oil resource estimate has propelled the country to second place behind Saudi Arabia. Experts estimate that ultimate recoverable volume stands at 300 billion barrels of crude oil. Over the last three decades cost of synthetic crude have fallen to about US$8 per barrel making oil sands a viable competitor on world oil markets. However, the production process remains very complex and causes various environmental impacts, among others Greenhouse gas emissions. The project seeks to investigate the carbon emission issues related to tar sands production, how new production technologies could mitigate the carbon emissions, and how policy incentives could affect the introduction of such technologies.  This research will shed light on the question of whether a large-scale expansion of tar sands production is environmentally sustainable and whether tar sands could help in reducing the world’s dependence on limited conventional petroleum reserves. 

Required Work: Depending on student interests the Earth Institute summer study could focus on:

 

                    Analysis of Kyoto and other existing/proposed legislation and their impacts on Canadian tar sands production.

·                                 Explore possible technological, operational and financial solutions to heightened carbon exposure from tar sand production.

·                                 Compare fully internalized costs of conventional crude oil versus synthetic (tar sands-derived) crude oil (internalization of security, environmental, other externalities)

Pre-requisites: Background in economics, basic understanding of environmental finance and economics, good presentation and organizational skills 

Thesis Mentor Information: Klaus Lackner, Earth and Environmental Engineering, kl2010@columbia.edu, Tel: 212-854-0304; and Arthur Small, SIPA

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Levy, Marc

 

Understanding the Spatial Dimensions of Global Poverty

 

Background: The student would be given the opportunity to work with a unique collection of spatial development indicators that has been developed for the UN's Millennium Development Project to investigate such different aspects of the overarching question,  "How biophysical conditions do the world's poor live under?"  More specific questions that are being addressed include "What level of association is there between deforestation and human well-being?"  "Is water scarcity correlated with poverty?"  "What environmental conditions are associated with the highest and lowest levels of infant mortality?"  "What intervening conditions mediate these general relationships?"  The primary purpose of this project is to support current planning, at both global and country levels, to meet the Millennium Development Goals.

 

Pre-requisites: Background in economics, basic understanding of environmental finance and economics, good presentation and organizational skills 

Thesis Mentor Information: Marc Levy, mlevy@ciesin.columbia.edu

Tel: 845-365-8964

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Liepert, Beate

 

Weather Dependence of Air Pollution and Atmospheric Transparency in and around NYC

 

Background: Particulate matter (aerosols) in the atmosphere is the most visible kind of air pollution. Aerosol particles are either emitted directly from industrial and household activity and traffic or they are end products of chemical transformations of anthropogenic and natural gases. Aerosol concentrations in the atmosphere can be measured because particles scatter and absorb sunlight proportional to their concentration. Brownish layers of aerosols are familiar features in urban areas and many quantitative studies of air quality in connection with human health exit. Although air quality improved in the last decade, it is suggested that smaller particles live longer and can be transported further away from the source regions and sometimes inter continentally. Here we want to focus on these remote effects of urban aerosols. Measurements of attenuation of sunlight with an optical instrument (microtops) in and around NYC will be analyzed and compared to satellite data and weather maps.

 

Required Work: The student will perform measurements, statistical data analysis and will discuss significant results in comparisons to other relevant data.

 

Pre-requisites: Familiarity with basic statistical methods is necessary. Basics in physics recommended, some familiarity with computer programs like excel are helpful.

 

Thesis Mentor Information: Dr. Beate Liepert, liepert@ldeo.columbia.edu, Tel. 845-365-8870

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Newton, Bob

 

The Age of the Arctic Halocline

 

Background: The Arctic Ocean is divided into a cold, relatively fresh layer at the surface and a warmer, relatively salty layer below.  Between the two is a “halocline” where the density of the ocean water increases sharply with depth.  The halocline keeps the warmer water away from the surface, and stops the permanent ice pack from melting in summer.  It also plays an important role in setting up Arctic Ocean currents by controlling density gradients.  During the 1990s, the Arctic saw major shifts in its climate, with ice thinning and receding; increases in major storms; higher temperatures; and melting tundra.  One of the changes is a partial breakdown in the halocline, which probably explains part of the loss of ice.  It is possible that we are heading for an Arctic climate in which the Ocean is ice-free every summer, which would be a major shift for the climate as well as for industry, culture and ecology in the North. 

 

Over the past 15 years, Lamont Doherty has collected a database of samples from the Arctic, including trace chemicals and isotope ratios that allow us to estimate how long ago a water sample last saw the surface.  We can use such “age” estimates to get the renewal times for different water masses, such as the halocline or the relatively fresh layer above it.  The goal of this project is to map the distribution of trace chemicals and ages in the surface and halocline layers of the Arctic Ocean.  The samples have already been collected and measured.  Most of the data has been quality-controlled, formatted and integrated.  The student’s role will be to complete the QC process and integrate some recent data with the existing database; to map the data on density surfaces; and then to analyze the resulting maps.  The data processing requires basic facility with PC tools (mostly Excel).  Matlab is used for mapping the data; the mentor will help the student learn and develop the required scripts.  Analysis of the maps will be done in the context of available data on the Arctic climate, including observations of winds, sea-ice distributions, and river runoff sources.  The work can be adapted to the student’s schedule.  If the work is done as a summer internship, the student will be expected to spend at least 20 hours per week on programming and data analysis; and to meet with the mentor for approximately 90 minutes 3 times per week.  If the work is done during an academic semester, the student will be expected to invest between 5 and 8 hours per week working on the project, and to meet with the mentor once each week for about 90 minutes.

 

Prerequisites: Familiarity with correlation techniques will be helpful, but we can guide the student through any that seem daunting.

 

Thesis Mentor Information: Bob Newton and Peter Schlosser

bnewton@ldeo.columbia.edu

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Newton, Bob

 

Modeling the Arctic as a "Global Estuary"

 

Background: Every year thousands of cubic kilometers of fresh water, either as sea-ice or as relatively fresh "polar" water, flows from the Arctic Ocean to the North Atlantic.  In the Nordic Seas, this fresh layer can affect the formation of the cold, dense water that fills the bottoms of most of the world's ocean basins.  When the fresh water outflow from the Arctic is high, we believe that deep-water formation slows down, and vice versa.

The formation of deep water, in turn, can impact on global climate, and some climatologists believe that a slowdown in deep water formation has led to large fluctuations in past climates.  We are running a series of model experiments to explore the impact of large-scale wind patterns on freshwater export from the Arctic.  The model is set up with a global ocean with sea-ice; and is forced with synthetic winds that simulate a variety of climate scenarios.  We want to see what the impacts are on the Arctic circulation, how freshwater export changes, and what that does to deep-water formation in the Nordic Seas.  We are looking for a student who would be interested in comparing the output of our model runs to observations.  The observations include: satellite-derived distributions of sea-ice, temperatures and sea-surface heights; coastal sea-surface heights from tide gauges and hydrographic data from ocean cruises. 

 

Required Work: The work can be adapted to the student’s schedule.  If the work is done as a summer internship, the student will be expected to spend at least 20 hours per week on programming and data analysis; and to meet with the mentors for approximately 90 minutes 3 times per week.  If the work is done during an academic semester, the student will be expected to invest between 5 and 8 hours per week working on the project, and to meet with the mentor once each week for about 90 minutes.

 

Prerequisites: The student should have a basic understanding of correlations, and be comfortable working with data.  We will use Matlab for most of the data processing, but prior experience in Matlab is not a requirement.

 

Thesis Mentor Information: Bob Newton, bnewton@ldeo.columbia.edu

and Bruno Tremblay, tremblay@ldeo.columbia.edu, Tel: 845-365-8767

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Nitsche, Frank

 

Distribution of recent deposition and contaminants in the Hudson River

 

Background: Many local studies of the amount and location of recent sediments and related contaminants have been conducted in the Hudson River Estuary. However, no systematic compilation exists that would provide a spatial overview of recent deposits and potential contaminant in the Hudson River Estuary. Recent sediment that has been deposited during the last 50 – 100 years can be identified by the analysis of radionuclide isotopes like ¹³⁷Caesium and ⁷Berrilium in sediment cores. This project will compile the results of previous analyses made by scientist in Lamont and the New York State Department of Environmental Conservation. The results will improve our understanding of the sediment budget and flux of the Hudson River system. It will be used to target future detailed investigation of specific depositional sites. The information on location and amount of contaminated sediment in the Hudson River and New York Harbor is also important for decision-makers such as NYSDEC, DEP, or Port Authority.

 

Required work: Compilation of existing data from different sources and mapping their spatial distribution will be done using a Geographic Information System (ArcGIS) on the Lamont campus.

 

Prerequisites: The student should have a background in environmental engineering, geography, or geochemistry; good computer skills, knowledge of GIS would an advantage, but is not necessary, as the student will learn the necessary skills during the project.

 

Thesis Mentor Information: Frank Nitsche,fnitsche@ldeo.columbia.edu, (845) 365 8746

and Robin Bell, robinb@ldeo.columbia.edu

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Nitsche, Frank

 

Study of flux and turbulence in the upper Hudson River Estuary

 

Background: The Hudson River Estuary between Manhattan and Troy, NY is subject to strong tidal motions. Several studies have been conducted to investigate flow conditions through different tidal cycles in the lower parts of the estuary using Acoustic Doppler Current Profiler (ADCP). However, only few measurements have been made in the upper part of the estuary. Good data for the whole estuary are needed to fully understand the system and to provide input for a hydrodynamic model. Additional measurements conducted as part of this study will increase our knowledge on the hydrodynamics and turbulence of the Hudson River and will help us to understand the flow and related sediment transport through the estuary. We will learn how the hydrodynamics of the river change with variations in the shape of the river cross-section. The results will complement the existing data and are important for calibration and validation of hydrodynamic models currently developed.

 

Required work: The student will assist in preparation, deployment and retrieval of an ADCP system in the Upper Hudson. This involves about five days of fieldwork on the Hudson River during the summer. The student will processes and analyze the data to derive the hydrodynamic properties of the different parts of the river. She/He will compare the new data with the existing data to discover similarities and differences between the different parts of the River. The analysis will be done using different computer software and MatLab routines.

 

Prerequisites: Background in oceanography or hydrology is useful, good computing skills, interest in fieldwork; knowledge of MATLAB would be a plus, but is not required.

 

Thesis Mentor Information: Frank Nitsche, fnitsche@ldeo.columbia.edu, (845)365 8746

and Martin Visbeck,

 

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Pekar, Steve

 

Developing a climate record for the New York City area for the past 7,000 years

 

Background: The primary goal of this study is to evaluate long-term climate variability (decadal to centennial scale) of the Hudson River region based on climate reconstructions for the past 7,000 years.  This will be accomplished by estimating salinity changes and fluctuations in freshwater discharge rates into the Hudson River.

 

This study will collect data from cores obtained from the Hudson River to elucidate climate changes in the New York City area as well as determine the evolution of the Hudson River.  This will be done using grain size analysis of the sediment, examination of the microfossils called foraminifers and collect and perform geochemical analysis on shell material from bivalves.

 

Prerequisites: Students should have a strong interest in earth science particularly in oceanography and/or geology.  Preference will be given to students having already taken earth science classes either in High School or at the college level. 

 

Thesis Mentor Information: Steven Pekar, pekar@ldeo.columbia.edu

Tel: 845-365-8362

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Pekar, Steve

 

Estimating sea-level and paleoenvironmental changes of the New York City area during the last 50,000 years

 

Background: During the last 50,000 years, sea level fell by at least 40 meters (130 ft) before rising 120 meters (400 ft) to its present height.  This study will examine core material obtained from a scientific expedition off the coast of New York City.  By examining shells formed by microorganisms (benthic foraminifers) and performing geochemical studies on these microfossils, sea level and paleoenvironmental changes will be ascertained for the offshore area of New York City for times up to 50,000 years ago. 

 

Prerequisites: Students should have a strong interest in earth science particularly in oceanography and/or geology.  Preference will be given to students having already taken earth science classes either in High School or at the college level.

 

Thesis Mentor Information: Steven Pekar, pekar@ldeo.columbia.edu

Tel: 845-365-8362

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Pekar, Steve

 

Reconstructing ocean circulation, ice volume in Antarctica and sea-level changes during the mini-greenhouse world of the early Miocene (16-21 Ma)

 

Background: During the early Miocene (16-21 Ma), the global climate apparently experienced a warming after the first climatic cooling of the Cenozoic at 34 Ma.  However, a debate still exists on the extent and magnitude of this switch to a mini greenhouse world.  This project is developing records that can evaluate paleoceanographic and climatic changes by looking at deep-sea sediments obtained from the Ocean Drilling Program drill ship, “JOIDES Resolution”.  This will involve performing grain size analysis and collecting microfossils called foraminifers from these sediments to use in obtaining geochemical data.  These data will be used to estimate seawater temperatures, paleocirculation patterns of the world’s oceans and evaluate ice-volume changes in Antarctica for this mini-greenhouse world. 

 

Prerequisites: Students should have a strong interest in earth science particularly in oceanography and/or geology.  Preference will be given to students having already taken earth science classes either in High School or at the college level. 

 

Thesis Mentor Information: Steven Pekar, pekar@ldeo.columbia.edu

Tel: 845-365-8362

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Pekar, Steve

 

Paleoclimate and paleoceanographic studies of an early Greenhouse World (late Paleocene 60-55 Ma)

 

Background: The early Paleogene represents a time of dramatic climatological and paleoceanographic changes that include the recovery after the K/T Event (65 Ma, the time that the dinosaur became extinct), and the ephemeral global hothouse world of the Late Paleocene Thermal Maximum (LPTM).  However, with the K/T Boundary and LPTM having garnered the attention of much scientific study in recent years, fundamental questions concerning paleoceanographic and climatic changes during the late Paleocene have remained unanswered.  In particular, little is known about the extent of the cooling that took place during the late Paleocene (59-57 Ma).  It has also been speculated that small ephemeral ice sheets may have existed in Antarctica during this time. 

 

Required Work: In this project, students will work on 60-55 million year old sediments obtained from the Ocean Drilling Program drill ship, “JOIDES Resolution” to decipher paleoclimatic and paleoceanographic changes during this so-called greenhouse world.  This will involve collecting microfossils called foraminifers to be used in obtaining geochemical data.  These data will be used to estimate seawater temperatures, paleocirculation patterns of the world’s oceans and determine whether significant ice sheets existed in Antarctica. 

 

Prerequisites: Students should have a strong interest in earth science particularly in oceanography and/or geology.  Preference will be given to students having already taken earth science classes either in High School or at the college level. 

 

Thesis Mentor Information: Steven Pekar, pekar@ldeo.columbia.edu

Tel: 845-365-8362

 

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Peteet, Dorothy

 

Paleoenvironments on Easter Island

 

Background:  Sediment cores from 2 craters on Easter Island are archives for pollen and macrofossils over millennia.  Previous research indicates that small changes in climate affect vegetation distribution and abundance on the island.  Key questions concerning these changes focus on the importance of palm trees on the landscape and the role of fire in this ecosystem.  The changes over millennia have implications for global climate change and for island ecology.

 

Required Work: Student will be expected to learn to identify the fossil pollen in the core and count samples to produce a pollen stratigraphy over several thousand years.  The project involves microscope research and data analysis using available literature.

 

Prerequisites: none

 

Thesis Mentor Information: Dr. Dorothy Peteet, peteet@ldeo.columbia.edu, tel. 845-365-8420

 

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Peteet, Dorothy

 

Coastal Alaskan Paleoecology and Paleoclimate

 

Background:  Previous research on Alaska's coastal vegetation indicates a distribution pattern of plant migration northwestward over thousands of years.  After the last ice age, trees migrated around the coast westward at different rates. Major gaps appear in our understanding of the rates of migration.  This project involves the macrofossil analysis of a peat core to understand the pattern of vegetational change in a remote region of Alaska.

 

Required Work: Lab analysis involves screening of samples, then identification of plant remains using a modern reference collection to produce a macrofossil stratigraphy over time.  From this record, we can infer migration rates and paleoclimatic patterns over the last 16,000 years.

 

Prerequisites: none

 

Thesis Mentor Information: Dr. Dorothy Peteet, peteet@ldeo.columbia.edu, tel. 845-365-8420

 

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Peteet, Dorothy

 

Hudson River Marsh Paleoecology from Iona Island, New York

 

Background: Ongoing marsh paleoresearch indicates dramatic changes in the Hudson Watershed over the last two millennia.  How widespread are these changes in the Hudson?  Analysis of macrofossils from a sediment core from Iona Island Marsh, NY is essential to understanding how widespread droughts

and human impact were to the Hudson River Valley.

 

Field Research: Collection of reference macrofossil plant material from Iona Island Marsh.

Lab Research: Use of screens to separate macrofossils from peat, and separation of macrofossils using microscope.  Generation of macrofossil stratigraphy and interpretation.

 

Prerequisites: none

 

Thesis Mentor Information: Dr. Dorothy Peteet, peteet@ldeo.columbia.edu, tel. 845-365-8420

 

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Rosenzweig, Cynthia

 

The Potential of Green Roofs to Solve the Problems of the Urban Heat Island Effect, Global Climate Change, and Storm Water Runoff

 

Background: The New York Ecological Infrastructure Study (NYEIS) is an ongoing multidisciplinary research partnership between the Earth Pledge Foundation Green Roofs Initiative, researchers and specialists from the Earth Institute at Columbia University, and other research organizations in the New York Metropolitan Region.  The goal of the study is to determine the potential of green roofs to address problems of the urban heat island effect, global climate change, and storm water runoff.  The project involves rooftop data collection and analysis including heat flux, runoff rates, and water quality as well as the development of process models to study the energy balance and hydrology of green roofs.    The project also includes cost-benefit analysis and policy-related research.  Over the past two years, several Barnard and Columbia students have worked on green roofs-related senior thesis projects.  

 

Prerequisites: None. Projects can be tailored to a student’s strengths.  The student must be willing to work as part of a multidisciplinary team and attend monthly project meetings.

 

Thesis Mentor Information: Dr. Cynthia Rosenzweig (Goddard Institute for Space Studies (GISS), the Columbia Earth Institute), crosenzweig@giss.nasa.gov; 212-678-5562

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Ryan, William B. F.

 

Mapping the distribution of sediments across the floors of the Pacific and Indian Oceans

 

Background: The sediment carpet on the ocean floor is imaged with sound. Sediment is the thinnest on the crests of the mid-ocean ridges and thickest on continental margins.

 

For fieldwork, lab work and/or data analysis: This is a project of data analysis using graphic tools and mapping software. We will also examine deep-sea cores obtained by drilling.  The goal is to map patterns of sediment type and thickness throughout these oceans and apply them to resolving the evolution of these oceans involving the shifting plates, changing climate and changing ocean circulation.  We will use a vast database of analog reflection profiles and then put the results in a digital database open to the public and supported by the National Science Foundation.

 

Pre-requisites: some background in physical geology or environmental sciences

 

Thesis Mentor Information: William B. F. Ryan (Marine Geology), billr@ldeo.columbia.edu,

Tel. 845-365-8312

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Sambrotto, Ray

 

Biological response to climate variations in the Arctic and Bering Sea.

 

Background: It is clear that polar regions will be impacted most from any change in the global climate.  Far less clear, is the extent to which marine biological processes will respond to climate warming, as well as the specific mechanisms that link climatic variations to polar food webs.   This project will focus on the biological productivity of the Bering Sea and adjoining Arctic Ocean.  Data analysis methods will be used on remotely sensed and compiled data on marine phytoplankton levels, sea-ice extent and atmospheric conditions to investigate how the production system of the region may respond to climate forcing.  This work is part of a larger project that is investigating the susceptibility of important resources such as industrial and subsistence fishing to climate change.

 

Pre-requisites: One semester of college level math, and one of biology and/or ecology.

 

Thesis Mentor Information: Dr. Ray Sambrotto (Biological Oceanography), sambrott@ldeo.columbia.edu, Tel. 845-365-8402

 

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Sambrotto. Ray

 

Seasonal response of coastal productivity to seasonal upwelling in the southern Caribbean

 

Background:  Each winter, favorable winds blow along the coast of Venezuela, bringing cool, nutrient laden water to the surface.  This produces a distinct seasonality in the local production regime that changes from low productivity (characteristic of most tropical waters) to high productivity.  Data analyses will be carried out on a seven-year time series of physical and biological data in the region that includes one El Nino - Southern Oscillation event.  The goals of the analyses will be to test for correlations in the time series that link the biological system to both the local and larger scale forcing as well as to clarify the biological changes that occur in response to upwelling in more detail.

 

Pre-requisites: One semester of college level math, and one of biology and/or ecology.

 

Thesis Mentor Information: Dr. Ray Sambrotto (Biological Oceanography), sambrott@ldeo.columbia.edu, Tel. 845-365-8402

 

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Sambrotto. Ray

 

The role of dormancy as a strategy for bloom forming diatoms in coastal waters

 

Background: In temperate and polar regions where organisms must survive extended periods during which growth is limited or impossible, strategies for over-wintering play a large role in determining the relative success of various populations.  This project will focus on the over-wintering strategy employed by some spring-bloom diatoms that produce a large population of cells that lie dormant in near-shore sediments until the following year, so that surviving cells can serve as the seed stock for the next bloom.  Fieldwork will be done to collect both vegetative populations from local waters as well as dormant cells from sediments.  Populations will then be cultured in the laboratory and genetic analyses performed in association with a molecular biology lab.  The genetic patterns will be analyzed together with the physics of the region to determine the role that gene flow plays in creating diatom blooms in coastal waters.

 

Pre-requisites: Two semesters of biology and/or ecology.

 

Thesis Mentor Information: Dr. Ray Sambrotto (Biological Oceanography), sambrott@ldeo.columbia.edu, Tel. 845-365-8402

 

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Sambrotto, Ray

 

Big fish in clear waters: Tuna production in the western equatorial Pacific Ocean

 

Background: The western equatorial Pacific is fairly unproductive compared to the eastern upwelling region.  In the east, nutrients enhance production and short food chains support massive levels of planktivorous fish and thus this region has received the lion’s share of scientific effort.  However, our standard biogeochemical assumptions are difficult to reconcile with the fact that the western equatorial Pacific Ocean supplies 40% of the world’s annual tuna catch.  This project will use remote sensing, data analysis and modeling to investigate how low levels of new production can be so efficiently transferred to higher trophic levels.  Particular attention will be given to atmospheric phenomena such as the tropical intraseasonal oscillation (with a 40-50 day period) may be associated with the entry of critical nutrients such as iron, phosphorus and nitrogen into the surface waters of the western equatorial Pacific. The process-level and time-series measurements will be integrated in a model of piscivirous fish populations to determine how and to what extent they may interact with the observed production fluctuations.

 

Pre-requisites: Two semesters of biology and/or ecology.

 

Thesis Mentor Information: Dr. Ray Sambrotto (Biological Oceanography), sambrott@ldeo.columbia.edu, Tel. 845-365-8402

 

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Schaefer, Joerg

 

Lessons from Abrupt Climate Changes recorded in glaciogenic surfaces at Long Islands, New York City and Hudson Valley

 

Background: One of the major issues facing society is abrupt climate change as a possible consequence of anthropogenic activities. The only tools available for studying the underlying processes and possible consequences of abrupt climate change include model simulations and reconstruction of past climate scenarios over periods when abrupt change occurred. The latter is the only data-based approach that allows us to gain insight into time scales and spatial patterns of abrupt climate change. We are presently developing new methods at L-DEO to study past terrestrial climate change in archives left behind by glaciers in moraine systems. The proposed activity would allow a student to acquire knowledge of past abrupt climate changes and to participate in the discussion and interpretation of the results in the context of their relevance for possible future abrupt climate changes driven by human activity.

During the Last Glacial Maximum (LGM), the Hudson Valley and the New York City area were covered by lobes of the Laurentide Ice Sheet (LIS). The LGM terminated abruptly. The retreating LIS left behind the terminal moraines represented by Long Island and glaciogenic surfaces along Hudson Valley. Information about the timing of this prominent continental glaciation is fundamental to understand the mechanisms underlying the drastic and abrupt climate changes during the last ice age.

We have investigated this topic since the summer of 2003 by mapping and dating various glacial surfaces on Long Islands (erratic boulders), New York City (glacially polished surfaces in Morningside-, Riverside- and Central Park), and in the Hudson Valley (glacially polished surfaces at Greenwood Lake). We apply the method of Surface Exposure Dating (SED), a modern and well-established tool of geochronology. The student will be educated in a forefront discipline of paleoclimatology. He/She will get insight into the entire spectrum of the SED method including sampling field-trips, mineral separation and isotope separation techniques, mass-spectrometric analyses and interpretation of the data within a defined paleoclimatic context. He/She will work with leading experts in the field.

 

Required work:  The student will be involved in sampling campaigns in the Hudson Valley, New York City and Long Islands (approx. 3 days@8 hours); sample processing, including mineral separation by physical and chemical means, column chemistry methods to separate ¹⁰Be/²⁶Al from quartz; approx. 15 hours per week) data interpretation and comparison with other abrupt climate change events (approx. 15 hours per week)

 

Pre-requisites: Interest in inter-disciplinary sciences (climatology, geology, geochemistry)

Basic knowledge in experimental lab-work with chemical reagents

 

Thesis Mentor Information: Joerg M. Schaefer (Geochemistry, schaefer@ldeo.columbia.edu, Tel 845 365 8703); Peter Schlosser (peters@ldeo.columbia.edu)
Seager, Richard

 

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Richard Seager

Late Victorian El Nino's: Impacts in India and China of late Nineteenth Century tropical Pacific climate variability

 

Background: This project addresses the issue of forcing of climate variability around the world, on timescales of years to decades to centuries, by variations of tropical Pacific ocean temperatures which vary as part of the  El Nino-Southern Oscillation, or ENSO.  ENSO is an irregular oscillation of the coupled atmosphere-ocean system.  Whether the tropical Pacific is warm or cold has dramatic consequences for weather and climate causing floods and droughts around the world.

 

In a recent book (Late Victorian Holocausts, Verso Press) Mike Davis has suggested that several enormous El Nino events in the late Nineteenth Century caused droughts in India and China that set in motion a tragic chain of events that caused massive famine and death.   We have completed a set of atmosphere model experiments that simulate the response of the global atmosphere to observed variations in the tropical Pacific ocean temperatures (taken from ship observations) from 1856 to the present.   These experiments allow checking the link between ENSO and Asian droughts in the

Nineteenth Century.

 

Required work: The work will involve analysis using statistics of the results of the model and comparisons to available data, some investigation of historical records (as referred to by Davis) and reading of the small amount of previous literature on Nineteenth Century tropical climate variability or what ever other phenomena is chosen.  Data analysis will be done using our Web-based Ingrid software that is quite user friendly.

 

Visiting Lamont one or more days a week, for at least part of the day, would be necessary for a total of about 5 hours per week (for non-summer students).

 

Pre-requisites: Some knowledge of statistics.   Basic correlation and regression.

Statistical significance such as t-tests.   Knowledge of statistics to identify spatial patterns, such as Empirical Orthogonal Functions, would be good.

Some knowledge of climate and meteorology is also required.

 

Thesis Mentor Information: Richard Seager, rich@maatkare.ldeo.columbia.edu, Tel: 845-365-8743

and Yochanan Kushnir, kushnir@ldeo.columbia.edu

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Seager, Richard

 

Tropical forcing of the Dust Bowl and other American droughts

 

Background: This project addresses the issue of forcing of climate variability around the world, on timescales of years to decades to centuries, by variations of tropical Pacific ocean temperatures which vary as part of the El Nino-Southern Oscillation, or ENSO.  ENSO is an irregular oscillation of the coupled atmosphere-ocean system.  Whether the tropical Pacific is warm or cold has dramatic consequences for weather and climate causing floods and droughts around the world.

 

In a recent book (Late Victorian Holocausts, Verso Press) Mike Davis has suggested that several enormous El Nino events in the late Nineteenth Century caused droughts in India and China that set in motion a tragic chain of events that caused massive famine and death.   We have completed a set of atmosphere model experiments that simulate the response of the global atmosphere to observed variations in the tropical Pacific Ocean temperatures (taken from ship observations) from 1856 to the present.   These experiments allow checking the link between ENSO and Asian droughts in the

Nineteenth Century.

 

This project will examine the causes of droughts in North America, particularly in the Great Plains.  The Dust Bowl drought of the 1930s will be a main focus.   The model simulations were modestly successful in simulating drought in the Great Plains in the 1930s and the work will involve understanding the mechanisms whereby variations of the tropical atmosphere-ocean system were able to force rainfall variations in America.   The work will also involve analyzing the causes of persistent droughts and wet periods in North America at other times since 1856. It could also involve examining the causes of the changes of tropical climate on timescales of several years to many decades that drove these extratropical changes.

 

Required work: The work will involve analysis using statistics of the results of the model and comparisons to available data, some investigation of historical records (as referred to by Davis) and reading of the small amount of previous literature on Nineteenth Century tropical climate variability

(or what ever other phenomena are chosen).  Data analysis will be done using our Web-based Ingrid software, which is quite user friendly.

 

Visiting Lamont one or more days a week, for at least part of the day, would be necessary for a total of about 5 hours per week (for non-summer students).

 

Pre-requisites: Some knowledge of statistics.  Basic correlation and regression. Statistical significance such as t-tests.   Knowledge of statistics used to identify spatial patterns, such as Empirical

Orthogonal Functions, would be good. Some knowledge of climate and meteorology is also required.

 

Thesis Mentor Information: Richard Seager, rich@maatkare.ldeo.columbia.edu, Tel: 845-365-8743

and Yochanan Kushnir, kushnir@ldeo.columbia.edu

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Steckler, Michael

 

Changing maps of a changing river: The evolution of the Earth's largest delta by GIS analysis of historical maps through 5 centuries

 

The Ganges-Brahmaputra Delta is the largest delta in the world, fed by these two great rivers, which supply it with 6% of the world’s sediment supply.  It is also one of the most densely populated places on Earth.  The rivers and the landscape they flow across are very dynamic; sedimentation in the delta is rapid and constantly shifting in response to floods and earthquakes. These dynamics have a direct impact on millions of people in the form of natural hazards and annual changes in the landscape.  In addition, the Ganges-Brahmaputra Delta is in a tectonically active region susceptible to large destructive earthquakes.  As a result of the combined effects of the fluctuations of the extreme fluvial system, slow tectonic tilting and sudden earthquake-produced deformation, the river courses are highly dynamic.  The most famous example is from the early 1800’s when the Brahmaputra River shifted up to 100 km from the Old Brahmaputra channel to the present Jamuna channel over a 30-year period following a severe earthquake and major flood.  Historical maps document this shift and associated changes in tributaries, but also an eastward migration of the main mouth of the Ganges. This objective of this project is to quantify historical changes in the rivers and delta to better understand the potential impact of future changes on the rapidly growing population.   The student will use collections of historical maps, together with high-resolution digital topography and satellite images of the current delta, to document and decipher the evolution of the Ganges-Brahmaputra River system.  Maps will be scanned and analyzed with a GIS system in order to quantify the spatial and temporal dynamics of the river.  The aim is to examine the interaction of this great river system with the ongoing tectonics of the delta.    Understanding this long-term influence on the river systems is essential for planning development and flood control strategies within a delta that is home to over 200 million people.  

 

Pre-requisites:  None.

 

Thesis Mentor Information: Michael S. Steckler, steckler@ldeo.columbia.edu,

Tel: 845-365-8479, Leonardo Seeber, nanno@ldeo.columbia.edu, and

Chris Small, small@ldeo.columbia.edu

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Dueling rifts: Stratigraphic evolution of the northern Gulf of California

 

Background: The northern Gulf of California is a transitional region between the oceanic ridge and transform system of the central and southern Gulf, and the continental San Andreas fault system of southern California. It contains multiple rift basins and volcanics that are still in the process of developing into a mid-oceanic ridge.  The voluminous amount of sediments supplied to the region by the Colorado River blankets the rifts and may have slowed the development of a ridge.  However, these sediments also preserve a record the history of the basins.  In May-June 1999, we acquired a high-resolution multi-channel seismic reflection data set during a 3-week cruise.  This data set consists of 3500 km of high-resolution images of the upper ~1000m of sediments with a 5 m vertical resolution. A small section of one of the lines is shown below.  The grid of data images the active deformation associated with the plate boundary zone in the northern Gulf of California.  Multiple parallel rifts are simultaneously active in this wide complex zone of regional extension.  Mapping the extensive faulting recorded by the sediments has been completed.  The next stage is to map the stratigraphic layers that can provide the temporal control of the relative evolution of the basins. Numerous layers mark changes in the tectonics.  Two parallel rift basins have clearly alternated in dominance both along their length and through time. The data has been loaded onto an industry-standard seismic interpretation workstation.  The student will map the seismic surfaces in 3D and use the interpretations to analyze the spatial and temporal history of the northern Gulf of California.

 

Pre-requisites:  Some college level physics preferred.

 

Thesis Mentor Information: Michael S. Steckler, steckler@ldeo.columbia.edu, Tel: 845-365-8479 and Gregory Mountain, mountain@ldeo.columbia.edu

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Stute, Martin

 

Redox Manipulations as in situ Arsenic Removal Technologies

 

Background: Arsenic is the second most common contaminant of concern at US Superfund sites.  Due to the recent lowering of the permitted level of arsenic in drinking water, many more sites may need to have arsenic removed from solution.  We have been working at a former landfill site in southern Maine, where ~300 ppb arsenic has been detected in groundwater.  Laboratory and field measurements indicate that this arsenic is of natural origin, and is mobilized from the underlying glaciofluvial sediment containing ~6 ppm arsenic.  This mechanism of arsenic mobilization may be much more common than previously suspected, and may be occurring at many unlined municipal landfills.

 

Arsenic is soluble in a relatively narrow Eh window, and is mobilized at this site by reducing conditions induced and/or maintained by the decomposition of organic-rich landfill leachate.  This site is currently under remediation with a groundwater extraction and treatment system, which we estimate would need to operate for more than 70 years to lower the dissolved arsenic concentrations to within regulated limits.  This treatment system uses an oxidation and precipitation/co-precipitation step to remove arsenic (as well as iron and other redox sensitive metals).  The feasibility of oxidizing and precipitating the arsenic in situ was investigated with a pilot field experiment and laboratory experiments.  The redox buffer capacity of the aquifer makes this remediation strategy difficult to accomplish.  Arsenic is also relatively insoluble under very low Eh conditions, in which solid arsenic sulfides are the thermodynamically stable phases.  We propose to conduct laboratory experiments to investigate the feasibility of promoting more strongly reducing conditions than occur naturally in order to enter the sulfide precipitation regime.  These conditions rely on increased activity of the microbial community; the preferred energy source and terminal electron acceptors of this microbial community will be investigated.  The overall goal of this project is to investigate the feasibility of inducing sulfide precipitation in situ.

 

This project will be primarily lab work (~30 hrs/week) and some data analysis (~10 hours/week); after completion of the lab work, more data analysis may be required.

 

Pre-requisites:  At least two semesters of college level chemistry, one semester cell or molecular biology.

 

Thesis Mentor Information: Martin Stute /Jim Simpson/Alison Keimowitz (Geochemistry, LDEO) martins@ldeo.columbia.edu, Tel. 845-365-8704

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Tremblay, Bruno

 

Modeling the Arctic as a "Global Estuary"

 

Background: Every year thousands of cubic kilometers of fresh water, either as sea-ice or as relatively fresh "polar" water, flows from the Arctic Ocean to the North Atlantic.  In the Nordic Seas, this fresh layer can affect the formation of the cold, dense water that fills the bottoms of most of the world's ocean basins.  When the fresh water outflow from the Arctic is high, we believe that deep-water formation slows down, and vice versa.

The formation of deep water, in turn, can impact on global climate, and some climatologists believe that a slowdown in deep water formation has led to large fluctuations in past climates.  We are running a series of model experiments to explore the impact of large-scale wind patterns on freshwater export from the Arctic.  The model is set up with a global ocean with sea-ice; and is forced with synthetic winds that simulate a variety of climate scenarios.  We want to see what the impacts are on the

Arctic circulation; how freshwater export changes; and what that does to deep-water formation in the Nordic Seas.  We are looking for a student who would be interested in comparing the output of our model runs to observations.  The observations include satellite-derived distributions of sea-ice, temperatures and sea-surface heights; coastal sea-surface heights from tide gauges and hydrographic data from ocean cruises. 

 

The work can be adapted to the student’s schedule.  If the work is done as a summer internship, the student will be expected to spend at least 20 hours per week on programming and data analysis; and to meet with the mentors for approximately 90 minutes 3 times per week.  If the work is done during an academic semester, the student will be expected to invest between 5 and 8 hours per week working on the project, and to meet with the mentor once each week for about 90 minutes.

 

The student should have a basic understanding of correlations, and be comfortable working with data.  We will use Matlab for most of the data processing, but prior experience in Matlab is not a requirement.

 

Thesis Mentor Information: Bruno Tremblay, tremblay@ldeo.columbia.edu, Tel: 845-365-8767 and Bob Newton, bnewton@ldeo.columbia.edu

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Vaillancourt, Robert

 

Modeling the bio-optical properties of phytoplankton cells to ascertain the importance of cell size, shape and composition on light absorption efficiency

 

Background: Phytoplankton are single-celled photosynthetic organisms that require the energy from sunlight to drive metabolic reactions.  The first step in the photosynthetic process is the absorption of light, and a complex suite of photosynthetic pigment/protein complexes embedded in the cells’ chloroplasts accomplishes this.  The efficiency of light absorption (and scattering) is determined by the types and amounts of these pigments, but also by the manner in which the cell is constructed.  It is important to understand the relationship between cell shape, size and pigment content and light absorption in order to derive useful relationships between photosynthesis in the sea and the species composition of the phytoplankton present at any time or place.  This summer intern project will use a computer bio-optical model for phytoplankton to better constrain the relationships between cell characteristics and their optical properties.  This information is useful for accurate parameterization of global ocean primary productivity models.

 

For fieldwork, lab work and/or data analysis: Computer modeling of bio-optical properties using PC computer and ‘OOPS’ model developed by Dr. Minsu Kim at Cornell University.  Student will be required to become familiar with some concepts of bio-optics and with the functioning of the OOPS model.  Input data for model will be a large dataset of empirically derived optical coefficients and pigment concentrations measured previously.   

 

Pre-requisites: Expertise with PC computers required, and some experience with computer models and optical theory of light absorption and scattering by particles is advantageous. 

 

Thesis Mentor Information: Dr. Robert Vaillancourt (Biological Oceanography). Email: vaillanc@ldeo.columbia.edu.

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Williams, Trevor

 

Using IRD analysis and ³He measurements to constrain the duration and magnitude of Miocene ice rafting events offshore of Prydz Bay, East Antarctica.

 

Background: Repeated pulses of icebergs were produced from the ancestral Lambert Glacier, Antarctica, (presently the world’s largest glacier), representing significant oscillations in the size of the East Antarctic ice sheet about 18-22 Myr ago. The evidence for the iceberg pulses comes from Ocean Drilling Program Site 1165, located ~500 km offshore from the glacier, where sedimentary layers rich in ice-rafted debris (IRD - grains significantly larger than those of the host sediment), alternate with layers containing very little IRD. However, it is difficult to say how long these ice rafting events lasted. Deposition of the IRD-rich layers in a short time would indicate a sudden collapse of the glacier, whereas a longer period of deposition would indicate a more gradual evolution of the glacier. Extraterrestrial ³He has a relatively constant flux to the seafloor though time, and therefore ³He measurement through these layers should provide valuable information on the duration of these events. Near Antarctica, there is also a contribution to the ³He measurement from ³He that accumulated on the ice sheet before it broke off as icebergs, which complicates the interpretation, but also might provide information on how much of the ice sheet broke up.

 

Laboratory work

Approximately 10 hours per week

-                      Sample preparation: weighing, powdering, and dissolution of the opal fraction of about 20 samples.

-                      sieve the >150 micron fraction, weigh the IRD, and analyze by binocular microscope.

-                      measure ³He (approx. 2 half-weeks for this step)

 

Pre-requisites: At least two semesters of college-level chemistry

 

Thesis Mentor Information: Trevor Williams (Antarctic marine geology),

trevor@ldeo.columbia.edu, tel: 845 365 8626 and  Gisela Winckler (³He, geochemistry),

winckler@ldeo.columbia.edu, Tel: 845 365 8756

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Winckler, Gisela

 

Developing a Sedimentation Model for the Equatorial Pacific

 

Background: Deep-sea sediment cores are an excellent archive of past climate conditions.  Their interpretation has allowed us to study oscillations between warm and cold periods; to understand the oceans role in climate; and to test hypotheses about how the planet moves between different climate states.  This work, which is at the heart of climate change science, depends on assigning ages to sediments along the core.  The core-depth to age mapping, called the "age model" is usually done by the method of "orbital tuning".  Foraminifera (small plankton) shells are measured for oxygen isotope ratios (18O/16O); and variations in the ratio reflecting changes in global ice volume are matched to variations in the Earths orbit.  However, recent studies at Lamont point to a potentially serious problem: There are systematic differences in sediment accumulation patterns derived from the widely used oxygen-isotope chronologies or from a second method based on constant-flux proxies (such as 3He from cosmic dust, or 230Th from Uranium decay).  A systematic bias in the oxygen-isotope chronology for Pacific Ocean sediments could be created by the interaction between bioturbation (the stirring of mud by bottom-dwelling critters) and climate-related cycles in the dissolution of calcium carbonate (that makes up the foraminiferal shells).  Specifically, too little time may have been assigned to periods of intense dissolution during ice ages, creating apparent accumulation rates that are too high, and vice versa during periods of better calcium carbonate preservation (warm periods). If a bias in the standard age model can be identified, it will be of fundamental interest for people studying paleo-climate and climate change.

 

The Project: We will develop a one-dimensional sedimentation model that can be used to test this and other hypotheses regarding age models for deep-sea sediment cores.  The model will take assumptions about variables such as accumulation, bioturbation, dissolution, and cosmic dust flux as inputs. Its outputs will be comparable to chemical proxies for the passage of time and changes in Earths climate.  The student will code the model in Matlab, with the assistance of the mentors!  The student will then run the model across a range of parameters and will apply the results to existing proxy records.  The output is expected to contribute immediately to ongoing work on the equatorial Pacific.

 

Prerequisites: Interest in paleoclimate and basic computing skills are required.

Familiarity with Matlab.

 

Thesis Mentor Information: Gisela Winckler, winckler@ldeo.columbia.edu,

and Bob Newton , bnewton@ldeo.columbia.edu