Atmospheric deposition is the major atmospheric pathway for persistent organic pollutant (POP) input to the large water bodies such as the Great Lakes and Chesapeake Bay (Baker et al., 1997; Eisenreich, Hornbuckle, and Achman, 1997) (Fig. 27.1). For semivolatile organic compounds, such aspolychlo-rinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), atmospheric deposition occurs via three processes: (1) wet deposition via rain and snow, (2) dry deposition of fine and coarse particles, and (3) gaseous air-water exchange. Because atmospheric particles are scavenged efficiently by precipitation, the magnitudes of both wet and dry deposition are usually controlled by the concentration of a pollutant on atmospheric particles. In contrast, gaseous air-water exchange consists of the volatilization of dissolved contaminants into the gas phase, and the opposite effect of absorption of gas-phase pollutants into the water column. Thus, the magnitude of gaseous deposition (absorption) is controlled by the concentration of the pollutant in the gas phase.
PCBs and PAHs are of particular concern in aquatic ecosystems due to their persistence, their tendency to bioaccumulate, and their toxicity. Although other major sources of these contaminants exist within the estuary (for example, wastewa-ter treatment discharges), atmospheric deposition may still be important, especially as management strategies are implemented to reduce point discharges, leaving atmospheric deposition as an uncontrolled source. PCBs are of particular interest in the Hudson River ecosystem due to the well-documented contamination introduced into the Upper Hudson River by plants operated by General Electric (USEPA, 2001). The Upper Hudson has therefore long been recognized as a source of PCBs
to the New York/New Jersey Harbor Estuary. Until recently, however, little information was available about sources of PCBs to the New York/New Jersey Harbor other than the Upper Hudson. In particular, almost nothing was known about atmospheric deposition of PCBs to the estuary. In order to quantify these inputs, the New Jersey Atmospheric Deposition Network (NJADN) was established. This network was designed based on the findings of two earlier atmospheric deposition networks, the Integrated Atmospheric Deposition Network (IADN) operating in the Great Lakes (Hoff et al., 1996; Hillery et al., 1998) and the Chesapeake BayAtmospheric Deposition Study (CBADS) (Baker et al., 1997). Both of these earlier networks were designed to capture the regional atmospheric signal, and thus monitoring sites were located in background areas away from local sources. However, many urban/industrial centers are located on or near coastal estuaries (for example, NY/NJ Harbor Estuary and NY Bight) and the Great Lakes (for example, Chicago, IL and southern Lake Michigan). Emissions ofpollutants into the urban atmosphere are reflected in elevated local and regional pollutant concentrations and localized intense atmospheric deposition that are not observed in the regional signal (Hoff et al., 1996). Higher at mospheric concentrations are ultimately reflected in increased precipitation (Offenberg and Baker, 1997) and dry particle fluxes of PCBs and PAHs (Franz, Eisenreich, and Holsen, 1998) and trace metals (Paode et al., 1998; Caffrey et al., 1998) to the coastal waters as well as enhanced air-water exchange fluxes of PCBs (Zhang et al., 1999; Nelson, McConnell, and Baker, 1998;Tottenetal., 2001) and PAHs (Bamford et al., 1999; Gigliotti et al., 2001).
Processes of wet and dry deposition and air-water exchange of atmospheric pollutants reflect loading to the water surface directly. This is especially important for aquatic systems that have large surface areas relative to watershed areas (for example, Great Lakes; coastal seas). Water bodies may also be sources of contaminants to the local and regional atmosphere representing losses to the water column. This has been demonstrated in the New York/New Jersey Harbor Estuary for PCBs, PAHs, PCDDs/Fs and nonylphenols (Dachs, Van Ry, and Eisenreich, 1999;Van Ry et al., 2000; Lohmann et al., 2000; Brunciak et al., 2001b; Totten et al., 2001; Gigliotti et al., 2001). However, many aquatic systems have large watershed to lake/estuary areas emphasizing the importance ofatmospheric deposition to the watershed (forest, grasslands, crops, paved areas, and wetlands) and the subsequent
leakage of deposited contaminants to the downstream water body (Fig. 27.1). Most lakes and estuaries in the Mid-Atlantic states have large watershed/water area ratios (for example, New York/New Jersey Harbor Estuary, Chesapeake Bay, Delaware River Estuary) emphasizing the potential importance of atmospheric pollutant loading to the watershed and subsequent release to rivers, lakes, and estuaries.
The NJADN was established a) to support the atmospheric deposition component of the New York/New Jersey Harbor Estuary Program; b) to support the Statewide Watershed Management Framework and the National Environmental Performance Partnership System (NEPPS) for New Jersey; c) to assess the magnitude of toxic chemical deposition throughout the State; and d) to assess in-state versus out-of-state sources of air toxic deposition. The NJADN is a collaborative effort of Rutgers University, the New Jersey Department of Environmental Protection (NJDEP), and the Hudson River Foundation. The NJADN is a research and monitoring network designed to provide scientific input to the management of the various affected aquatic and terrestrial resources. This chapter will present results of NJADN through January 2001, including atmospheric concentrations and deposition of PCBs and PAHs relevant to the NewYork/New Jersey Harbor Estuary.
Was this article helpful?