93 



-3- 



-Not all pollutants entering the lower Hudson- 

 Raritan estuary from outfalls, upstream sources, 

 and runoff are washed into the Bight since 

 particle-associated contaminants settle out in 

 the estuary. The runoff and wastewater contri- 

 butions in the table (which were based on the 

 assumption of total entry into the Bight) are, 

 therefore, higher than they should be (and the 

 direct Bight sources — i.e., ocean dumping and 

 atmospheric deposition) are smaller than they 

 should be. It has been estimated, for example, 

 that only about 20% of the petroleum hydrocarbons 

 entering the lower Hudson-Raritan estuary are 

 washed into the Biaht. 



-The estimates on which the table is based 

 considered ocean-dumped dredged material to be a 

 separate source of contaminants despite the fact 

 that much of the contaminant burden of such spoils 

 is of estuarine or riverine origin. This double- 

 entry bookkeeping exaggerates the total inputs to 

 the Bight and results in an underestimation of 

 percentage contributions from ocean dumping and 

 atmospheric deposition sources. 



-There may also be some double accounting between 

 municipal wastewater sources (generally discharged 

 into streams) and gauged runoff (riverine flow) . 



-Most of the data on which the estimates in the 

 table are based are 9-13 years old. Since that 

 time, wastewater treatment plants have been 

 upgraded (i.e., reducing contaminant levels in 

 effluent and increasing them in sludges) and the 

 total amount of sewage processed has increased. 

 Quantities of ocean-dumped sewaae sludge currently 

 are nearly double what they were a decade ago. 



-Contaminants in ocean-dumped sewage sludge are 

 much more biologically available than those of most 

 other sources because most sludge contaminants 

 adhere to tiny particulates which settle very slowly 

 onto a "fluffy" bottom layer of sediments. In the 

 case of dredged material, particularly for heavy 

 metals, biological availability is likely to be 

 exceedingly limited given the high proportion of 

 metals that are an integral component of the 

 sediment's geochemical matrix. Actual dredged 

 material contributions of metals are, therefore, 

 greatly exaggerated, while effective sludge 

 contributions should be much higher than specified. 



