Fine sediments enter the Bight by discharge from rivers and tidal inlets, and by 

 dumping, particularly of dredged materials that have accumulated in New York 

 Harbor. Domestic and industrial wastes from land also contribute to elevated con- 

 centrations of organic carbon and toxic metals (Swanson, 1977) and a wide variety 

 of synthetic organic compounds (O'Connor, J.M., et al., 1981) in the sediments. 



Water movements in the Bight are highly variable. Over the middle and outer 

 shelf, waters generally move to the south-southwest, parallel to the bathymetric con- 

 tours. The average flow is about 5cm/s(0. 1 knots) near the surface, reduced to about 

 1 cm/s (0.02 knots) near the bottom. On the outer shelf, storm-induced winter cur- 

 rents of 3 to 10 days are common (Mayer, et al., 1979). Water temperature follows 

 the well-known seasonal cycle of heating and stratification in summer and vertical 

 homogeneity in winter. 



While boundaries between the inner and outer Bight are poorly defined and con- 

 stantly changing, the inner Bight does have two important features that tend to limit 

 its capacity to flush contaminants to the open ocean: 



1 . The two-layer flow near the mouth of New York Harbor is dominated by flow 

 from the Hudson-Raritan estuary. The less dense surface layer flows seaward, 

 generally parallel to the New Jersey coast. The lower, denser water of the Bight 

 flows into the estuary. Fine sediments that are rich in pollutants and organic 

 carbon tend to sink, be entrained in the bottom waters, and undergo the par- 

 tially closed cyclical transport common in estuaries. 



2. East of the region of strong river influence, a clockwise circulation gyre is evi- 

 dent for part of the time. Its western edge tends to be located over the head of 

 the Hudson Shelf Valley. While water flow can be up or down valley, up-valley 

 flow has been measured for extended periods of time (Beardsley, et al., 1976). 

 These impermanent up-valley flows and the clockwise gyre tend to reduce the 

 flushing of contaminants from the inner Bight or apex. 



Historical Changes 



The broad historical trends in human influences on the Bight are functions of 

 striking increases in population density and energy usage. The human population of 

 the counties bordering the Bight increased exponentially from about 10,000 in 1675 

 to over 16 million in 1970. Population stabilized in the period from 1970 to 1980 for 

 the first time since American Indians were driven from the region by Europeans in 

 the 1600s (O'Connor, J.S., 1981). 



From the 1850s to 1940, energy usage very gradually increased in the coastal fringe 

 of the Bight. Even in the early 1800s, however, the New York metropolitan region 

 was established as the rapidly expanding focus for development in the United States. 

 By 1810, New York City's population exceeded that of Boston, and the city became 

 the largest in the nation. Prosperous European nations invested heavily with capital, 

 goods, and technology in North America, and New York was a principal beneficiary 

 of this investment through trade, services, and manufacturing (Squires, 1981). The 

 Port of New York reached its peak in 1 87 1 as an import/ export center, handling 7 1 

 percent of the nation's foreign trade, but as this share declined. New York's commer- 

 cial, financial, and industrial growth continued (Boddewyn, 1981). 



Beginning in the 1940s, energy consumption soared. This spurt of energy con- 

 sumption coincided with continuing growth in population and (with some excep- 

 tions) industry and services through the 1960s (O'Connor, J.S., 1981). 



Until the mid-l700s, garbage and other wastes were dumped into open gutters, 

 rivers, or onto land to feed pigs and chickens. These practices continued into the 

 1850s in some areas while sewers and cesspools were being constructed. By 1806 it 

 was clear to the New York City Board of Health that more extensive sewers needed 

 to be constructed throughout the populated areas and that thecity aquifers could no 

 longer provide enough potable water (Loop, 1964). By 1842 the original Croton 

 aqueduct carried water to the city from 60 km (37 mi) to the north. This aqueduct was 



48 



