A basin-wide approach to dredged material management in New York/New Jersey Harbor

Abstract

In the last decade, an area of increasing estuarine research in the New York/New Jersey Harbor has been the identification of toxic contaminant sources, mapping of contaminant levels in water and sediments, and assessment of contaminant accumulation in biota. The accumulation of anthropogenic contamination in the harbor’s sediments has occurred for centuries, primarily from land-based municipal and industrial sources. Contaminants from land-based sources introduced into surface waters rapidly become scavenged by suspended particles that then tend to settle to the bottom, primarily in deep areas, such as berths and navigation channels. Several million cubic meters of sediments must be dredged annually to clear navigation channels. In the past, the dredged material was disposed in a designated ocean site. However, in1992, new testing procedures were implemented, and much of the harbor’s dredged material was determined to be unsuitable for ocean placement. It is ironic that these restrictions came at a time when the quality of harbor sediments is improving, largely because of pollution controls implemented as a result of the Clean Water Act and other environmental measures put in place by government and industry. For example, the harbor-wide concentration of mercury has decreased to 0.7–0.8 ppm, a level that is approaching the pre-industrial background level. Nevertheless, in certain areas of the harbor, there remain sufficiently high concentrations of contaminants to merit concern and to create serious problems for sponsors of dredging projects. Development of a basin-wide sediment management strategy is necessary to guide port decision-makers in their efforts to clean-up contaminant sources, to dredge regional waterways, and to ameliorate the contaminated sediment disposal problem. The backbone of this strategy is the integration of the data from an ongoing field monitoring and modeling program with a parallel investigation of watershed and airshed sources and sinks using industrial ecology methodology.