tributary rivers (Huggett et al., 1974). For manganese, iron, cobalt, and nickel, the 

 river inputs substantially exceed treatment plants. Near one large sewage outfall, 

 concentrations of heavy metals in sediments were 10 to 100 times those in uncon- 

 taminated areas, indicating that most of the metals were deposited near the source. 

 Other surveys and studies of heavy metals could not identify the sources, especially in 

 Baltimore Harbor and Elizabeth River, where large quantities of metals are present 

 in sediments, but both industries and sewage treatment plants have contributed 

 (Cronin et al., 1974). 



Potentially toxic chemicals are frequently, perhaps continuously, introduced into 

 the Chesapeake Bay from sources other than sewage treatment plants. They have 

 been identified as one of the three most serious threats to the health of the Bay 

 (Huggett et al.. 1977; Cronin et al., 1977). Substantial efforts have been made to 

 preclude introduction of toxicants, as in the Federal Toxic Substances Control Act 

 of 1976, Maryland's Safe Disposal of Designated Hazardous Substance Act, and 

 similar legislation in Virginia (Huggett et al., 1977). While it is by no means certain 

 that industrial and domestic wastes meet present standards of National Pollution 

 Discharge Elimination System permit statements, every new industry is required to 

 assure compliance. Principal problems appear to arise from old industries, old 

 sewage treatment systems, and the vast accumulations of metals, oils, and 

 unidentified pollutants in the sediments of Baltimore Harbor, Elizabeth River, and, 

 to a lesser concentration, other sites ( Jaworski, 1 98 I ; Office of Water Planning and 

 Standards, 1977; Tsai et al., 1979). 



The Environmental Protection Agency's Chesapeake Bay Program gave early and 

 high priority to some of the problems of toxics in the food chain. They have sup- 

 ported or are supporting projects on: 



• Sedimentology of the Chesapeake Bay 



• Baseline Sediment Studies to Determine Distribution, Physical Properties, Sedi- 



mentation Budgets, and Rates 



• Chesapeake Bay Sediment Trace Metals 



• The Characterization of the Chesapeake Bay: A Systematic Analysis of Toxic 



Trace Elements 



• Investigation of Organic Pollutants in the Chesapeake Bay 



• Interstitial Water Chemistry 



• Sediment and Pore Water Chemistry 



• Monitoring Particle-Associated Toxic Substances and Suspended Sediment in 



the Chesapeake Bay 



• Fate, Transport, and Transformation of Toxics: Significance of Suspended Sedi- 



ment and Fluid Mud 



• Animal Sediment Relationship 



• The Biogenic Structure of Chesapeake Bay Sediments 



• Inventory and Toxicity Prioritization of Industrial Facilities Discharging into the 



Chesapeake Bay Basin 



• Chemistry of Wet and Dry Fall to Lower Chesapeake Bay 



• Aqueous Effluent Concentrations for Biotesting 



• Toxic Point Source Assessment of Industrial Discharges to the Chesapeake Bay 



Basin 



• Biofractionation of Industrial Discharges 



• Evaluation of Bioassay Methodology for Application to Chesapeake Bay and 



Other Estuaries (Davies, 1980; Office of Research and Development, 1980). 



Excellent descriptions of the chemical burden of waters, sediment, and biota will 

 result, and much is being learned about the sources. Only the last project is directed 

 toward improved comprehension of the biological effects of toxicants in this and 

 other estuaries — a critical area for future studies. 



Chlorine is the most widely used biocide to disinfect the effluents from sewage 

 treatment plants, some food processing plants, and other materials. It is also 

 employed to minimize sliming and fouling in the tubes and pipes of generating 



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