690 
In reviewing these tables, it is apparent that for most contaminants, 
the proportion added to the New York Bight via sewage sludge dumping is 
generally small i.e. 1-10% of the total. One exception is PCB's (Bopp 
et al., 1981; O'Connor et al., in press b). A second possible exception 
is DDT and its metabolites; however, there are insufficient data on the 
total loadings of this family of compounds to be certain of the relative 
contribution made by sewage sludge (O'Connor et al., in press b). 
Sewage sludge does not capture impressive fractions of most contaminants 
that enter sewage treatment plants. Much more than half of most contam- 
inants is discharged in the effluent, leaving a relatively small fraction 
in the sewage sludge that is ocean dumped. The only exception of 
consequence is carbon (Mueller et al., 1976). 
Ocean dumped sewage sludge contributes roughly 30% of the total PCB 
loading to the New York Bight with dredged materials contributing approxi- 
mately 70% (Bopp et al., 1981), but some fraction of the dredged material 
PCBs is sequestered in the dumpsite mound. Bopp et al. (1981) also 
estimate that 25% of the PCBs in dredged material is from upstream 
wastewater discharges either raw or treated, from which the PCBs later 
settle out downstream by being adsorbed on harbor sediments. Other 
riverine and estuarine PCB inputs are likely far smaller, probably less 
than 10% of dredged material inputs (Schubel et al., in press). O'Connor, 
et al. (in press d) also have recently estimated the relative percentage 
contributions of the sources of PCBs to the Apex (Table 4). These 
figures indicate that ocean dumped sewage sludge contributes 19-26% of 
the PCBs; this generally agrees with Bopp's (1981) estimates. Dredge 
material contributes 51-61% of the PCBs. 
2.3. Sewage Sludge Dumping in the New York Bight at the 12-Mile Site 
(22 km) 
Ocean dumping of sewage sludge from the United States occurs, 
at present, only at the 12-Mile site (see Figure 1). The original 
sewage sludge dumpsite in the Bight apex was established in 1924. 
The amounts of sewage sludge dumped at the apex 12-Mile site from 
1960 through 1980 are shown in Figure 2. The amounts have increased 
