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Chesapeake Bay sediment models
Marine Pollution Bulletin
Chesapeake Bay Sediment Models EPA has revealed results from a two-dimensional model that has indicated sediments may be the largest contributor of nutrients to the Chesapeake Bay system. The sediments are a sink for nutrients that have entered and settled in the Bay sediments from diverse sources, including sewage treatment plants, runoff, and algal decay. During the calm summer months when oxygen levels are low, a massive nutrient exchange between these sediments and the water column occurs. The model, which has only recently become operational, is designed to predict dissolved oxygen, nitrogen, phosphorus, chlorophyll, and salinity levels in the two dimensions of depth and longitude and can be used to produce a three-dimensional picture when these levels are assembled for sections across the width of the Bay. The model is expected to treat the effects of nutrient loading on the entire Bay rather than to predict conditions in a specific location. Even though only in its infancy, the model indicates reductions in nutrient loadings will be ineffective against development of anoxic conditions until the residual nutrients reserves in the sediments are remobilized and depleted at an unknown date in the future. A much more sophisticated three-dimensional model is also being developed by EPA and the US Corps of Engineers to determine sediment nutrient levels in the Bay through time. This model, which will require some 3 years to develop, will be time-variable rather than assume steady-state summer conditions, as required by the current two-dimensional model. The three-dimensional model will also be able to predict nutrient levels based upon variable source inputs. Neither model will be directly applicable to other estuarine systems, but both could be used to develop models for other specific locations.
Three East Coast Dredge Sites Proposed The Environmental Protection Agency (EPA) has proposed final designation of three dredged material ocean dumpsites off the US East coast. The sites, currently used under interim designations, will be designated to accept materials from dredging of the ports of Savannah, Georgia; Charleston, South Carolina; and Wilmington, North Carolina. Dredged annually, each harbour produces some 1 million m 3 of sandy sediment, which has been bioassayed and has shown no significant environmental toxicity to marine life. No negative environmental impacts have been observed or are anticipated at the dumpsites that are located on the outer continental shelf and that have been in use prior to the 1970s. The South Carolina site has been enlarged to accommodate a 4 year harbour deepening project, but will be reduced in size when the project is complete.
States Control TBT Antifouling Paints In March 1987 the States of Maryland and Virginia enacted legislation governing the distribution, sale, and use of antifouling paints containing tributyltin (TBT). In Maryland from 1 December 1987 the Antifouling 264
Paints-Regulation Act will prohibit the sale, use, distribution, or possession of antifouling paints containing TBT except where the paint has demonstrated an acceptable release rate and is for use in a commercial boatyard on vessels greater than 25 m in length or with aluminium hulls. The acceptable release rate is defined as a rate equal to or less than 5 p.g cm -2 per day. North Carolina has already passed antifouling paint controls and both New York and New Jersey plan to introduce similar laws shortly.
DDT and PCB Levels Still High The California State Mussel Watch Program has reported that DDT, PCB, and dieldrin continue to plague the state's waters despite restrictions or prohibitions on their use. The Program monitors chemical contaminants in mussels taken from over 100 sites along the California coastline, including bay and estuarine locations. The Program reported mussels from the Inner Harbor area of Richmond, California, contained DDT tissue levels of 2.9 ppm wet wt, which is below the US Food and Drug Administration's action level of 5.0 ppm. Studies are being conducted by the regional water quality board to determine effects this DDT contamination may be having on the immediate area of Richmond Harbor and San Francisco Bay. Source control efforts at a former pesticide plant in the Los Angeles/Long Beach harbour area have resulted in steadily decreasing DDT concentrations in that region. San Diego Bay mussels still contain total PCB tissue levels above the Food and Drug Administration's action level of 2.0 ppm. The 1985-1986 levels of 2.2 ppm wet wt show a reduction from previous measurements of 2.4 and 3.8 ppm in 1984-1985 and 1982-1983, respectively. The pesticide dieldrin contaminated mussels in two drainages to Monterey Bay, with readings of 0.47 ppm in mussels from one drainage exceeding the Food and Drug Administration's action level of 0.3 ppm wet wt in shellfish. Various synthetic organics originating from the inland agricultural lands were found in other drainages to Monterey Bay and numerous pesticides were found in a lagoon in Ventura County, north of Los Angeles. The Southern California bays of Anaheim and Newport were found to contain mussels with elevated chlordane levels.
Enquiry into Aquaculture in B.C. The burgeoning salmon farming industry in British Columbia was slowed down on 30 October 1986, when Premier William Vander Zalm placed a moratorium on new fish-farm licences and decided to have a B.C. FinFish Aquaculture Inquiry into the province's fishfarming industry. Mr. David Gillespie, a Kamloops, B.C., lawyer, was appointed chairman of the inquiry b y the Honourable Jack Kempf, Minister of the B.C. Ministry of Forests and Lands, on 6 November, with instructions to have his report ready by 12 December 1986. Mr. Gillespie's terms of reference called f o r recommendations on 5 points: 1. the impacts of the industry on commercial fisheries, markets, and physical
Chesapeake Bay Sediment Models EPA has revealed results from a two-dimensional model that has indicated sediments may be the largest contributor of nutrients to the Chesapeake Bay system. The sediments are a sink for nutrients that have entered and settled in the Bay sediments from diverse sources, including sewage treatment plants, runoff, and algal decay. During the calm summer months when oxygen levels are low, a massive nutrient exchange between these sediments and the water column occurs. The model, which has only recently become operational, is designed to predict dissolved oxygen, nitrogen, phosphorus, chlorophyll, and salinity levels in the two dimensions of depth and longitude and can be used to produce a three-dimensional picture when these levels are assembled for sections across the width of the Bay. The model is expected to treat the effects of nutrient loading on the entire Bay rather than to predict conditions in a specific location. Even though only in its infancy, the model indicates reductions in nutrient loadings will be ineffective against development of anoxic conditions until the residual nutrients reserves in the sediments are remobilized and depleted at an unknown date in the future. A much more sophisticated three-dimensional model is also being developed by EPA and the US Corps of Engineers to determine sediment nutrient levels in the Bay through time. This model, which will require some 3 years to develop, will be time-variable rather than assume steady-state summer conditions, as required by the current two-dimensional model. The three-dimensional model will also be able to predict nutrient levels based upon variable source inputs. Neither model will be directly applicable to other estuarine systems, but both could be used to develop models for other specific locations.
Three East Coast Dredge Sites Proposed The Environmental Protection Agency (EPA) has proposed final designation of three dredged material ocean dumpsites off the US East coast. The sites, currently used under interim designations, will be designated to accept materials from dredging of the ports of Savannah, Georgia; Charleston, South Carolina; and Wilmington, North Carolina. Dredged annually, each harbour produces some 1 million m 3 of sandy sediment, which has been bioassayed and has shown no significant environmental toxicity to marine life. No negative environmental impacts have been observed or are anticipated at the dumpsites that are located on the outer continental shelf and that have been in use prior to the 1970s. The South Carolina site has been enlarged to accommodate a 4 year harbour deepening project, but will be reduced in size when the project is complete.
States Control TBT Antifouling Paints In March 1987 the States of Maryland and Virginia enacted legislation governing the distribution, sale, and use of antifouling paints containing tributyltin (TBT). In Maryland from 1 December 1987 the Antifouling 264
Paints-Regulation Act will prohibit the sale, use, distribution, or possession of antifouling paints containing TBT except where the paint has demonstrated an acceptable release rate and is for use in a commercial boatyard on vessels greater than 25 m in length or with aluminium hulls. The acceptable release rate is defined as a rate equal to or less than 5 p.g cm -2 per day. North Carolina has already passed antifouling paint controls and both New York and New Jersey plan to introduce similar laws shortly.
DDT and PCB Levels Still High The California State Mussel Watch Program has reported that DDT, PCB, and dieldrin continue to plague the state's waters despite restrictions or prohibitions on their use. The Program monitors chemical contaminants in mussels taken from over 100 sites along the California coastline, including bay and estuarine locations. The Program reported mussels from the Inner Harbor area of Richmond, California, contained DDT tissue levels of 2.9 ppm wet wt, which is below the US Food and Drug Administration's action level of 5.0 ppm. Studies are being conducted by the regional water quality board to determine effects this DDT contamination may be having on the immediate area of Richmond Harbor and San Francisco Bay. Source control efforts at a former pesticide plant in the Los Angeles/Long Beach harbour area have resulted in steadily decreasing DDT concentrations in that region. San Diego Bay mussels still contain total PCB tissue levels above the Food and Drug Administration's action level of 2.0 ppm. The 1985-1986 levels of 2.2 ppm wet wt show a reduction from previous measurements of 2.4 and 3.8 ppm in 1984-1985 and 1982-1983, respectively. The pesticide dieldrin contaminated mussels in two drainages to Monterey Bay, with readings of 0.47 ppm in mussels from one drainage exceeding the Food and Drug Administration's action level of 0.3 ppm wet wt in shellfish. Various synthetic organics originating from the inland agricultural lands were found in other drainages to Monterey Bay and numerous pesticides were found in a lagoon in Ventura County, north of Los Angeles. The Southern California bays of Anaheim and Newport were found to contain mussels with elevated chlordane levels.
Enquiry into Aquaculture in B.C. The burgeoning salmon farming industry in British Columbia was slowed down on 30 October 1986, when Premier William Vander Zalm placed a moratorium on new fish-farm licences and decided to have a B.C. FinFish Aquaculture Inquiry into the province's fishfarming industry. Mr. David Gillespie, a Kamloops, B.C., lawyer, was appointed chairman of the inquiry b y the Honourable Jack Kempf, Minister of the B.C. Ministry of Forests and Lands, on 6 November, with instructions to have his report ready by 12 December 1986. Mr. Gillespie's terms of reference called f o r recommendations on 5 points: 1. the impacts of the industry on commercial fisheries, markets, and physical