With the 8-hr maximum ozone National Ambient Air Quality Standard (NAAQS) decreasing from 75 to 70 ppb, modeling results indicate that use of postcombustion controls on coal-fired power plants in 2018 could help keep regions in attainment. By operating already existing nitrogen oxide (NO) removal devices to their full potential, ozone could be significantly curtailed, achieving ozone reductions by up to 5 ppb in areas around the source of emission and immediately downwind. Ozone improvements are also significant (1-2 ppb) for areas affected by cross-state transport, especially Mid-Atlantic coast regions that had struggled to meet the 75 ppb standard.

Shrimp farms cause environmental impacts in coastal ecosystems, compromising water quality by discharging effluents rich in nutrients and organic matter. The impacts of shrimp farming are often investigated by the unit effect of a farm. In this study, a harvest time series generator is used to analyze the impact of the synergistic effect of several shrimp farm harvests in a tropical estuary. Two other scenarios with harvests concentrated during spring and neap tides were also analyzed, showing waste management techniques that can reduce the impact of shrimp aquaculture on coastal areas. A hydrodynamic circulation and water quality model were implemented to evaluate the dispersion of pollutants using different discharge combinations. The harvesting scenarios were compared to a scenario without the activity. Results indicate that shrimp farming is not the main anthropogenic source of pollution in the estuary studied. There were no significant differences in the average and maximum variations in nutrient and organic matter concentrations between the different management techniques.