HW-6 - due 4/15/08
Groundwater in the Great Hungarian Plain
The Great Hungarian Plain is located in the eastern half of Hungary,
and
has unconfined and confined aquifers (fig,
fig)
Download the spreadsheet ghp.xls.
1)(10p) Stable isotopes in precipitation and groundwater
-
Plot dD vs. d18O
for the precipitation and groundwater data plus the Global Meteoric
Water
Line in one graph. What is your interpretation of the graph?
-
Plot d18O in precipitation as a
function
of temperature (monthly data). What is the slope of the temperature
effect?
-
During the last ice age, the isotopic composition of the ocean was
enriched
in d18O by about 1 permille,
because
sea level was lower and more water was trapped in the ice sheets.
In order to compare the groundwater data for glacial and holocene
periods,
we need to correct for this effect in the source region and subtract 1
permille from the glacial d18O
values.
-
Plot the corrected d18O as a
function
of 14C age for the groundwater data. What is your
interpretation
of the graph?
2) (15p) Noble gases
-
Plot Xe vs Ne for water is solubility equilibrium with the atmosphere
at
an elevation of 120m and the groundwater Xe and Ne data similar to the
plot in Heaton (1981) (fig). Under
the assumption that excess air is unfractionated air, what is the
derived
noble gas temperature range you get?
-
The spreadsheet also contains the derived noble gas temperatures using
the iterative method. Plot the noble gas temperature vs 14C
age.
-
Convert the corrected groundwater d18O
data into temperatures ussing the slope of the relationship derived for
precipitation. How do the noble gas and d18O
based glacial/interglacial temperatures compare? Which estimate do you
think is more reliable and why?