Air quality is a big actor in the health of the Bay. Nitrogen Pollution Years ago, water and air pollution were considered two separate problems. Only recently has research shown the close link between these environmental threats. Emissions of NOx are created by automobiles, electric utility plants, factories, boats, lawn-cutting equipment, and construction equipment. The NOx eventually settle back to the surface and enter the water directly or are washed from soil and impervious surfaces during rain to a water source.
Scientists estimate that about one-quarter of the nitrogen entering the Bay is from the air.
These nitrogen compounds reach the surface through either dry deposition or wet deposition. Dry deposition is atmospheric deposition that occurs when particles settle to the earth's surface and attach to a surface or are absorbed. Wet deposition is atmospheric deposition that occurs when rain or snow carries gases or particles to the earth's surface. Excess nitrogen in the Bay's water causes dense algal blooms which block out the sunlight needed by the submerged aquatic vegetation. It is the submerged vegetation, or bay grasses, that provides protection and habitat for fish and crabs.