NONPOINT SOURCE POLLUTION LESSON PLAN

Toxic Contaminents in Long Island Sound Worksheet

In 1994, NOAA’s National Status and Trends Program published a study of sediment toxicity in the coastal bays that surround Long Island Sound in New York and Connecticut (Wolfe, et al., 1994). The study analyzed sediment samples in four different ways:

(a) Amphipods were exposed to test sediments, and the number of animals alive after 10 days’ exposure was used as an indicator of toxicity;

(b) Clam larvae were exposed to water that had been mixed with test sediments and then filtered to remove sediment particles; normal development and survival after 48 hours’ exposure were used as criteria of toxicity;

(c) Microtox® bacteria were exposed to chemicals extracted from sediments using dichloromethane (an organic solvent); and

(d) Chemical analyses were conducted to determined the concentration of a wide variety of potential contaminants, including heavy metals and various organic compounds.

Use internet research and/or library resources to answer the following questions:

  1. What is a Microtox® test, and what does EC50 mean?
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  3. Define:
    Effects Range-Low (ERL)
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    Effects Range-Median (ERM)

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    PAH

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    Table 1 summarizes information on contaminants in Long Island Sound known to come from various sources.

    Table 2 summarizes some of the results from the sediment study. Toxicity data for tests of sediments from each site are compared to similar tests using sediment from a control area that were known to be non-toxic to the test organisms. Toxicity data in Table 2 are given as a percentage of the positive response in the relevant control test. A positive response may be survival (amphipods and clam larvae), normal development (clam larvae), or intensity of bioluminescence (Microtox® bacteria). So a value of 75 means that the number of organisms that survived exposure to a test sediment was 75% of the number of organisms that survived exposure to the control sediment. A value greater than 100 means that more organisms survived exposure to the test sediment than the number of organisms that survived exposure to the control sediment.

    Contaminant concentration data are presented as Hazard Factors. These factors are related to previously determined values of ER-L and ER-M. An HF of 0 means that the concentration is less than the ER-L for that contaminant. An HF between 0 and 1 means that the concentration is between the ER-L and ER-M for that contaminant, so an HF of 0.5 means that the concentration is halfway between the ER-L and ER-M. An HF greater than 1 means that the concentration is equal to the HF multiplied by the ER-M. So an HF of 2 means that the concentration is twice the ER-M; a concentration of 3 means that the concentration is three times the ER-M, and so forth.

  5. Which of the sources in Table 1 contributes the most potential contaminants?
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  7. What do the data in Table 1 suggest about contaminants in Industrial Discharges?
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  9. Data in Table 1 suggest that Wastewater Treatment Plants account for a large proportion of oil and grease, phosphorus, chlorinated hydrocarbons, and some heavy metals. Why?
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  11. What are the major contaminants associated with Urban Runoff? What are some possible sources of these contaminants?
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  13. Why was more than one type of toxicity test used in this study?
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  15. Why are toxicity tests needed in addition to chemical analyses of potential contaminants?
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  17. Which of the four toxicity tests seems to be most sensitive to contaminants?
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  19. What do the data in Table 2 suggest about the relationship between toxicity and concentrations of potential contaminants?
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Table 1

Estimates of Annual Loadings for Selected Pollutants to Long Island Sound from Seven Major Sources
(from Farrow et al. 1986)

   Pollutant Percent of Total Loading from Major Sources a
A B C D E F G
 Total Nitrogen
37.6 2.1 <0.1 7.3 3.7 0.1 49.2
 Total Phosphorus 66.2 0.1 0.1 7.9 0.5 <0.1 25.2
 Heavy Metals              
 As 51.7 <0.1 1.7 8.1 3.4 <0.1 35.1
 Cd 28.2 <0.1 <0.1 5.1 <0.1 <0.1 66.7
 Cr 18.9 4.2 0.4 7.1 8.0 0.4 61.0
 Cu 31.9 3.4 5.2 7.2 1.2 0.2 50.9
 Fe 4.9 <0.1 <0.1 15.7 34.8 2.2 42.4
 Hg 25.4 0.6 0.1 7.3 <0.1 <0.1 66.6
 Pb 14.7
2.3 <0.1 43.0 <0.1 <0.1 40.0
 Zn 22.6 2.9 1.6 12.8 1.9 0.1 58.2
 Oil & Grease 66.6 0.4 0.3 32.7 - - -
 Chlorinated
 Hydrocarbons
90.3 1.3 - 5.4 3.0 - -
 Fecal Coliforms 1.0 <0.1 - 47.3 - - 51.7
 Sludge 100 - - - - - -

a   A= wasterwater treatment plants
B= industrial discharges
C= power plants
D= urban runoff
E= Cropland runoff
F= forestland runoff
G= upstream sources

(-) indicates no estimates made for this pollutant in the catergory.


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