Atmospheric mercury deposition industrial sources

The Chesapeake Bay is the largest estuary in the United States and the Baltimore metropolitan area, one of the heavily industrialized areas on the east coast, is located on the western shore of the Chesapeake Bay. The Chesapeake Bay has a large surface-to-volume ratio (mean depth is 7 m) and it is therefore particularly vulnerable to the influence of atmospheric deposition (5). Previous studies have demonstrated that Baltimore s urban atmosphere is an important source of PAHs and PCBs to the Chesapeake Bay (77, 18). Previous studies around the Chesapeake Bay have quantified the concentrations of inorganic and organic contaminants in wet and dry deposition at rural sites in the watershed (3-5, 20, 23). Additionally, a paper discussing the impact of urban-derived gaseous and particulate mercury appears as part of this book (27). In this chapter the focus is on metals in wet deposition. 

Mercury is regulated as a priority pollutant in accordance with the Clean Water Act (CWA). The CWA establishes the basic structure for regulating the discharge of pollutants to waterways and is designed to ensure that all waters are sufficiently clean to protect public health and/or the environment. However, if waters and their sediments become contaminated from sources such as atmospheric deposition and discharges from industrial, municipal, or agricultural operations, toxic substances could concentrate in the tissue of fish and wildlife. 

There are many types of water pollutants coming either from point sources such as sewage and industrial waste or from nonpoint sources such as agricultural runoff and storm water drainage. Water impairment includes excess levels of nutrients, metals (primarily mercury), sediment and organic enrichment due to agricultural activities, industrial and municipal discharges, atmospheric deposition, and unknown specific sources. More recently, pharmaceuticals and personal care products have been detected in U.S. waters at low concentrations. 

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