Program: air pollution, water pollution, and the 

 combined effects of air and water pollution on 

 coastal estuaries that lead to de-oxygenation. 



Air Pollution 



The Clean Air Act amendments mandate State 

 use of air quality models to demonstrate the 

 effectiveness of proposed approaches for reduc- 

 ing air pollution in highly polluted areas. 

 Researchers at EPA and the North Carolina 

 Supercomputing Center in Research Triangle 

 Park. NC are developing a decision support sys- 

 tem to satisfy a wide range of related air quality 

 modeling, information and analysis needs. New 

 computational capabilities enable improved air 

 quality models to address multipollutant interac- 

 tions among acidifying species, oxidants and 

 aerosol, and interactions with meteorology. 

 These complex, three-dimensional, time-depen- 

 dent models are used to evaluate alternative pol- 

 lution control strategies where interactions at 

 different scales, from urban to regional, are crit- 

 ical and require new approaches made possible 

 only through high performance computing. The 

 North Carolina Department of Environment, 

 Health and Natural Resources is testing an early 

 prototype of an urban airshed modeling system. 



Water Pollution 



Contaminated bottom sediments and the associ- 

 ated decrease in water quality are a major prob- 

 lem in hundreds of rivers, lakes, harbors, estuar- 

 ies, and near-shore areas of oceans. In order to 

 remediate this problem and evaluate possible 

 management alternatives for the disposition of 

 these toxic sediments, EPA-supported 

 researchers at the University of California- Santa 

 Barbara are developing computer intensive 

 three-dimensional, time-dependent models of the 

 hydrodynamics, particle transport, and sediment 

 bed dynamics coupled with meteorology. 

 Significant biochemical reactions that affect the 



fate of contaminants are also included in the 

 models. Work currently focuses on the Great 

 Lakes region of the United States. Figure 1 

 shows that redistribution of toxic sediments in 

 Lake Erie due to a large storm is highly depen- 

 dent on wind direction and speed, and water 

 depth. 



Linked Air and Water Pollution 



Interactions between pollutant media, such as air 

 and water, often significantly affect the environ- 

 ment. Air and water pollution both contribute to 

 an overabundance of nutrients in coastal estuar- 

 ies causing lack of oxygen and eventual decline 

 of commercial productivity of the estuaries. 

 Researchers at EPA's Environmental Research 

 Laboratories in North Carolina and Georgia, and 

 the Chesapeake Bay Program Office in 

 Maryland are developing loose linkages between 

 air and water quality models to study the impact 

 of nitrogen deposition by air and water sources 

 on the decline of coastal estuaries of the 

 Chesapeake Bay. 



In some cases, only minor feedbacks exist 

 between the different media. Loosely linking 

 current single-medium models retains the known 

 features and complexity of each model. This 

 linkage provides additional information for more 

 effective policy determination by individual pol- 

 lutant media decision making communities. 



SPONSORING AGENCIES AND 

 ORGANIZATIONS 



EPA 



PERFORMING ORGANIZATIONS 



EPA's Chesapeake Bay Program Office 

 EPA's Environmental Research Laboratories 

 North Carolina Department of Environment. Health 



and Natural Resources 

 North Carolina Supercomputing Center 

 University of California - Santa Barbara 



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