Polychlorinated Biphenyls in Sediments of the Tidal Hudson River, New Yorkt Richard F. Bopp," H. James Simpson, Curtis R. Olsen, and Nadia Kostyk Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964, and Department of Geological Sciences, Columbia University;New York, New York 10027
As the result of discharges of PCBs from two manufacturing facilities on the upper Hudson River between ca. 1950 and 1976, recent sediments of the tidal Hudson have been contaminated to an average level of -10 ppm. This is 1-2 orders of magnitude higher than levels in a number of other large rivers and estuaries that have been studied. The degree of contamination decreases regularly with distance downstream from the source. Downstream changes in PCB composition along the axis of the Hudson can be understood qualitatively in terms of suspended matter-water partitioning of PCB components. The presence of 137Csin the sediments can be used as an independent indication of sediment deposition since the era of atmospheric testing of nuclear weapons. 137Cs and PCB depth profiles in cores are used to determine a first-order PCB budget for sediments of the tidal Hudson and to indicate regional levels of PCB contamination prior to the large point-source discharges to the upper Hudson. The Hudson River has received a major point-source input of polychlorinated biphenyls (PCBs) from ca. 1950 to 1976 from the waste discharges of two General Electric capacitor manufacturing plants located -60 km upstream of the southernmost dam on the river at Troy, NY ( I ) . Contaminated water and suspended matter passing over the dam have been the single dominant source of PCBs entering the tidal Hudson for the past 25 yr. This report presents a summary of our PCB data for more than 150 Hudson sediment samples analyzed over the past 3 yr. Experimental Section
By convention, sample locations on the Hudson are usually reported in terms of mile points (mp), which are the number of statute miles upstream of the southern tip of Manhattan Island (mp 0) measured along the channel (Figure 1).The dam a t Troy (mp 154) marks the northern limit of tidal influence. Salt penetration may be as far upstream as mp 60-80 during summer low-flow conditions and between mp 10 and 20 during conditions of seasonal high freshwater flow. Sediment samples were collected with a Mills gravity corer, a piston corer, or a Shipek grab sampler. Sediments were either stored frozen or air dried under a hood, ground with a mortar and pestle, and stored in air-tight aluminum cans. For PCB determinations, air-dried sediment samples were mixed with 20% water by weight ( 2 ) ,and the dry weight was determined by heating a small subsample overnight at 120 "C. The samples were transferred to preextracted paper thimbles and Soxhlet extracted overnight into azeotropic hexaneacetone with one change of solvent. Soxhlet extraction efficiency was checked by extracting the same sample twice. The first extract contained >98% of the total PCB in each peak. Heating air-dried sediment samples overnight a t 60 "C caused no reduction in abundance of even the lowest chlorinated PCB homologues present (dichlorobiphenyls),and on this basis it was assumed that air drying did not alter the PCB composition of our sediment samples. Polar coextractants were removed by column chromatography on alumina deactivated with 6% water (w/w) ( 3 ) .Elemental sulfur was removed by treating the extract with
+ Lamont-Doherty Geological Observatory Contribution No. 3058. 210
Environmental Science & Technology
HC1-activated copper dust ( 4 ) . PCBs were separated from DDT and its analogues by chromatography on silica ( 5 ) .All concentration steps were carried out in a Kuderna-Danish apparatus. All solvents used were pesticide grade (Baker, Resi-Analyzed, or Mallinckrodt, Nanograde). The gas chromatograph used in this study was a Varian Model 3700 with dual 63Nielectron capture detectors operated in the constant-current,pulsed mode. Two glass columns were used, a 6 f t X 2 mm i.d. packed with 4% SE-30/6% OV-210 on 80-100-mesh Chromosorb W H P and a 6 f t X 2 mm i.d. packed with 1.5%OV-17/1.95% QF-1 on 80-100-mesh Chromosorb W HP. The columns were operated a t 195 "C with an injection-port temperature of 210 "C and a detector temperature of 240 "C. Standards of Aroclors 1242,1016, and 1254 were ohtained from the EPA at Research Triangle Park, NC, and run a t least daily. Concentrations are expressed as micrograms of PCB per gram dry weight of sediment (ppm).Aroclor 1242 standards were used for quantification of the Hudson River samples since this commercial PCB mixture most closely matched the sediment extracts (Figure 2). Individual peak quantifications were based on average 1242 and 1254 compositions reported by Webb and McCall(6). Sections of sediment cores were analyzed for 137Cs,134Cs, and 6oCoby y-ray spectroscopy using a lithium-drifted germanium detector and a multichannel analyzer. R e s u l t s a n d Discussion
13'Cs and PCBs. The use of an independent indicator of the recent nature of sediments is extremely important when studying anthropogenic pollution in river, estuarine, or lacustrine systems which all tend to have spatially heterogeneous patterns of sediment accumulation. For this purpose, we have used the sediment content of 137Cs,a radionuclide with a half-life of 30 yr which first entered the system in measurable amounts from global fallout in 1954. First delivery of fallout 137Csapproximately coincides with the beginning of the point-source discharge of PCBs to the Hudson from the two General Electric facilities which began operation in 1947 and 1952. Sediments containing 137Csdefinitely have a post1954 component and should reflect the PCB contamination from the upstream capacitor plants while sediments with no l37Cs were deposited before 1954 and should primarily reflect the levels of PCB contamination that existed before the point-source discharges. Some areas of the Hudson, including much of the natural channel and subtidal banks, have very low and sometimes nondetectable (
