River Water Quality

General Problem: Where do contaminants in river water come from?

Tip 5: Keep data sets simple!

• Use tables, with well-defines rows and columns, whenever possible.
  • Excel tables work just fine! Text versions with tab-separated columns are just fine, too.
  • Label the columns with easy to understand names in the first row.
  • Indicate the units of measurement in the second row.
  • Indicate null-values unambiguously. The characters "NULL" work just fine.
• Organize you data into a reasonable small number of tables. A single table ought to contain enough information that you can do something useful with it (e.g. make a plot).
• Supplement a set of tables with "metadata", that is files of text that explain the dataset:
  • orgainization of data
  • authors, dates, and reason that the data was collected
  • measurement techniques
  • known anomalies and problems

Things to do:

1. Familiarization.

   Familairize yourself with sources of important dissolved substances commonly found in river water.

   Download the 12 data files and the station information file (see list, below, and save them as Excel files. These water quality data are from the U.S. Geological Survey's National Stream Water-Quality Monitoring Network, and were retrieved from their web site:

   http://wwwrvares.er.usgs.gov/wqn96cd/html/wqn/wq/wq.htm.

   The original data are stored in inscruitable "punch-card image" format. The versions here have been reformatted, and to some extent edited, to make manipulation with Excel possible.

   Examine the original format of the Esopus Creek (Shandaken, NY) Major Dissolved Ion dataset, 01262198.maj and its format description, wq.fmt to see what the original format was like. How would you convert it into a format that Excel can access? What are all those -999.999's doing in the file?

   Look at the locations on the sites on the regional topographic map and on the regional geological map. Examine each data type and make sure that you understand what each one is and why it is included in the water quality data?
   
   

2. Variation in major element concentration with streamflow Compute the mean, standard deviation, standard error, and number of points for each major element at each of the four stations. Which variables have enough data to be worth using? Make a separate summary table comparing the values of the mean and standard deviation of the four stations. Plot each major element with enough data versus streamflow. Which variables show a correlation to the streamflow? Fit a trend line to these major elements. What is the predicted value of the variable at the highest streamflow rates? At the lowest streamflow rates? Save these numbers in your summary table. Plot each major element versus the day in the year. Which variables have an annual cycle?
   
   
3. Rain as a source of major elements. Think about the major element data. If values of major elements show a significant correlation with the streamflow rate, compare the major values at maximum streamflow rates to the average concentrations of these elements in rain from the maps below. At which stations are the concentrations in rain comparable to the concentrations at maximum streamflow rates? At which stations are the concentrations in rain different from the concentrations at maximum streamflow rates? Why do these differences occur? If the values of major elements show a significant annual variability, explain why. Calculate the molar concentration of Cl and Na at each site, and their ratio. How much of the input to the stream is salt? Where does the salt come from?
   
   
4. Variation of nutrients with stream flow. Take the mean, standard deviation, standard error and number of good points for the nutrients at each of the four stations. Which variables have enough data to be worth using? Make a separate summary table comparing the values of the mean and standard deviation of the four stations. Plot each nutrient with enough data versus streamflow. Which variables show a correlation to the streamflow? Fit a trend line to these nutrients. What is the predicted value of the variable at the highest streamflow rates? At the lowest streamflow rates? Save these numbers in your summary table. Plot each nutrients versus the day in the year. Which variables have an annual cycle? Take the annual mean and standard error of nutrients with an observable annual cycle. Plot these means and their standard errors versus time in years. Do this also for SO₄, Cl and Si in the table of major elements. Fit a trend line to the annual means for each element. Is pollution increasing or decreasing with time? What are the sources of error in your estimate of changes in pollution?
   
   
5. Land use and nutrient sources Plot means and standard deviations of the nutrient and water quality data versus the percentage of drainage basin area that consists of different types of land. Convert drainage basin area to units of km². Which variables show a strong correlation to the land types? Why?
   
   
6. Physical Properties of River Water Take the mean, standard deviation, standard error and number of good points for the physical data at each of the four stations. Which variables have enough data to be worth using? Make a separate summary table comparing the values of the mean and standard deviation of the four stations. Plot dissolved oxygen, pH, and temperature versus one another. Calculate best fit lines for each of the plots. How much would temperature have to rise in the summer time for different rivers to have substantial fish kills? What are the sources of errors in your estimate? Plot pH versus streamflow rate. Why and where does pH correlate with streamflow rate? What other factors are influencing the pH of the water?
   
   
7. Summarization Work on your lab report. Think about the factors which influence levels of pollution in these rivers. In what ways are they similar and in what ways are they different?

Water Quality Datasets

1. Esopus Creek
   • Major Elements
   • Nutrients
   • Physical Properties
2. Hudson River
   • Major Elements
   • Nutrients
   • Physical Properties
3. Maurice River
   • Major Elements
   • Nutrients
   • Physical Properties
4. Raritan River
   • Major Elements
   • Nutrients
   • Physical Properties
5. Maps and other information
   • pH map
   • calcium map
   • chlorine map
   • potassium map
   • sodium map
   • ammonia map
   • NO₃ map
   • SO₄ map
   • topographic map (high-quality PostScript Version)
   • Station List
   • geologic map of northeastern North America
   • US geologic map and map key
   • water quality standards information