Polychlorinated biphenyls in the Hudson River Recent tre& in the distribm'on of PCBs in water, sediment, d f i h
Mark R Brown Mary B. Werner Ronald J. S l m New Yo& State Lkparimem of Environmental Conservation Albany, N. Y 12233
Karl w.Simpson New York State Department of Health Albany, N. Y 12233 Polychlorinated biphenyls W B s ) were fvst detected in Hudson River fish in 1969, but it was not until 1975 that their presence was perceived as a serious environmental contamination prob lem (I. 2). Results of fh-monitoring activities conducted by the New York State Department of Environmental Conservation (DEC) demonstrated that FCB concentrations in Hu&n River fish were substantially higher than the 5.0-ppm temporary tolerance level established by the Food and Drug Administration (FDA) (3). In 1975, two capacitor-manufacturing facilities, located at Fort Edward and Hudson Falls (Figure 1) and owned by the General Electric Company (GE), were identified as the primary sources of contamination. It was estimated that during a 30-y period the facilities had discharged PCBs to the Hudson River at a rate of 14 kgld (2,
6% Envim. Sci. TBchtml..W. 19. No. 8,1885
maintain navigability for the Chamdischarge was predominantly com- plain Canal system. In 1973, a dam just posed of the industrial mixtures A m downstream of the PCB-discharging facilities at Fort Edward was removed, clor 1242 and 1016. Action was brought against GE by exposing highly contaminated nearDEC and other parties for alleged vio- shore sediments. In the following year lation of the New York State Environ- an estimated 650,000 m3 of contamimental Conservation Law. A settlement nated sediments was mured from the agreement signed in 1976 provided for former dam pool (4, @. Maintenance dredging of navigaa stepwise reduction in daily FCB discharge by the GE facilities to 1 g in tional channels in the upper Hudson 1977 and for the expendiNre of $7 mil- during a 25-y period has removed more lion to assess both the contamination than 500,000 m3of sediment (4,s). Beproblem and possible remedial actions tween 1974 and 1977, sediments were (5). Based on data generated by snbse- removed from the river channels in quent investigations (2, 6, 7j, remedii areas where considerable deposition measures, including a no-action alter- had occurred following the removal of native, were evaluated (4, @. Limited the Fort Edward Dam. The dredge measures to control PCB losses from spoils (natural materials dredged from highly contaminated exposed sediment the river to improve navigation), which upstream of a former dam site were un- cqit+ed an estimated 70,000kg of dertaken using funds provided by the settlement agreement. the former Fort Following the elimination of direct discharge of PCBs,the riverbed, which had been the primary sink for PCBs, became the major supplier of the contaminant to the Hudson River system. A Mdkm reach of the riverbed, from Hudson Falls through New York Harbor, has been contaminated with PCBs (Fimue 1). The oortion of the river beI RNr;a ioGthe F & r a l b ~ t t ~at~m y is a tidal t river and estuary. From Fort Edward to my,the river is largely a series of pools formed by low-level dams that
4). Purchase records indicate that the
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W 1 3 - 9 3 6 ~ 1 9 . 0 8 1 . 5 0 / 0 Q I985 American Chemical Society
river bank to prevent erosion. In 1978, these areas were restabil i i , and one deposit containing about 7500kg of PCBs was excavated and moved to a clay-lined landfill (4, 8). By 1978, the mass of PCBs remaining in the Hudson River system was estimated at 63,500 kg in the river bank deposits, 134,ooOkg in the upper river, and 91,000 kg in the lower river (2, 7).
Monitoring program As part of a fish-monitoring program conducted by the DEC Division of Fish and Wildlife since 1977, resident and migrant fish species have been collected at sites throughout the upper and lower portions of the Hudson River. Fish were caught using electroshock techniques and giUnetting or were purchased from commercial fishermen. Specimens were collected at predetermined locations within two weeks of a specified date to minimizethe effects of potential seasonal variations in contaminant concentrations (9). Fillets of whole sides of scaled fish were prepared from individuals longer than 150mm; shorter fish were analyzed with heads and viscera removed (9). PCBs have been analyzed in aquatic macroinvertebrates collected from the Hudson since 1977 by the New York State Department of Health. Net-spinning caddis 0y larvae (Trichoptera:Hydmpsychidue)were collected from five stations in the upper river at fiveweek intervals each year from June through September. PCBs also were analyzed in residues collected from multiplate samplers suspended for fiveweek periods at 15 stations in the upper and lower river (IO,11). Between 1978 and 1981, zooplankton samples were collected at 13 sites in the lower Hudson and analyzed for PCBs as part of a study completed at New York University Medical Center (12). Macromplankton samples were collected using 571-pm-mesh nets and sorted to unigeneric groups such as Cammarus, Neomysis, Leptodera, and Crangon. Microzooplankton samples retained on a 76-fim-mesh net were not sorted.
Between 1977 and 1981, the U.S. Geological Survey (VSGS) maintained five monitoring stations in the upper and lower portions of the river. Each year, approximately 150 water samples were collected in the upper river and about 25 samples were taken from the lower river. These were analyzed for concentrations of PCBs and suspended sediments (13). Since 1982, only the upper river has been sampled, and the empbasis has been on monitoring highnow events, such as spring melting of snow.
In 1976 and 1977, an extensive prc-
FIGURE 1
H h n River drainage Imino
gram of sediment sampling and m a p ping that involved collection of more than loo0 grabandare samples was conducted by DEC in the upper Hudson River (6, 7).Sediment texture, particle size distribution, and volatile-solid and PCB concentrations were determined (14). In the lower river, more than 150 core samples were collected and analyzed for FCBs by the LamontDoherty Geological Observatory, Palisades, N.Y. (15).EPA conducted a sediment survey at 30 sites in the lower river in 1976 and resampled most of those sites in 1981 (16, 17). In 1983, EPA collected and analyzed in-river sediment samples from 66 sites in a fivemile reach downstream of Fort Edward (18).
PCB declim in binta Mean PCB levels in most of the fish species sampled between 1970 and 1974 exceeded the FDA's 5.0-ppm tolerance level (3). Subsequent monitoring has demonstrated that PCB concentrations are higher in fish from the
upper river than in those from the lower river and that concentrations are decliiing in virtually all monitored fish species. Mean total PCB concentrations in fiiets from largemouth bass (Micropterus salmoides) collected near Stillwater declii from 145.3 pg/g in 1977 to IO.Zpg/g in 1981, while those collected near Catskill in the estuary d e cliined from 29.5 pg/g in 1977 to less than 1.0 pg/g in 1981 (9, 19-21). Median striped bass (Morone samtilis) PCB concentrations declined from 9.9 pg/g in 1978 to 2.6 pglg in 1982 (Figure 2). During the same period, the proportion of fish that showed PCB concentrations below the FDA t e m p rary tolerance level increased from 1196 to 75 96. Length and weight distributions were similar among annual striped bass samples with the exception of the 1979 sample, which was composed of generally smaller fish. The preponderance of small striped bass in the l i t e d 1979 collection may have exaggerated the decline between 1978 and 1979 (Figure 2). Only 10% of the Environ. Sci. Technol., MI. 19. No. 8. 1985 657
FIGURE 2
Mean and cumulative relalive frequencies of PCB concentrations in fillets of striped bass collected from the Hudson River estuary 1978-W
chromatography methods, which have been used recently in biological monitoring, should help to clarify these obseNations.
Decline in waterborne PCBs
fish in the 1983 sample were below the current FDA limit of 2.0 ppm. A strong correlation between PCB and lipid concentrations was observed for all Hudson River resident species but not for anadromous (river-spawning) species. Patterns of contamination are probably obscured by intraspecific variations in migratory behavior including year-round residency, overwintering, and presence in the river only during spawning (21). Lipid-dependent PCB accumulation is consistent with the known lipophdic character exhibited particularly by the higher chlorinated PCB congeners. Mean lipidbased FCB concentrations in yearling pumpkinseed (Lepomis gibbosus) declined from 1079pglg in 1979 to 36pg/g in 1982. During the same perid, mean lipid-based PCB concentrations in brown bullhead (Ictalunrs nebulosus), g o l d f ~(Carassius ouram), and largemouth bass declined from 2510pg/g, 6761 pglg, and 6010pg/g to 428 pg/g, 310 pg/g, and loo0 pg/g, respectively. Spatial and temporal trends in PCB concentrations in caddisfly larvae and multiplate residues are generally consistent with the findings of the fishmonitoring program. PCB concentrations in estuarine plankton are widely variable by species, location, and season. During the 4-y period, a weak gradient in PCB concentration in plankton was noted between the upper and lower -58
Envimn. Sci.Technol..Vol. 19. No. 8, 1985
portions of the estuary, although intermediate locations often exhibited peaks of PCB concentration. Between 1978 and 1981, a progressive decline in PCB levels was apparent in zooplankton, Gammancr spp. in particular, although anomalies based on local and seasonal variations do exist. A comparison of the relative concentrations of Aroclor 1016 and Aroclor 1254 suggests that the PCB declines observed in certain biological samples can be attributed primarily to declines in the less chlorinated PCB congeners. In samples of resident and anadromous fish alike, the pattern of decline in total PCB concentration is dominated by the decrease in Aroclor 1016 (9,21). The concentration ratio of Aroclor 1016 to Aroclor 1254 in GMvMncr spp. declined from a mean of l .5 ppm in 1979 to 0.76 ppm in 1980, although this shift is not apparent in other data (12). Although the significance of this comparison may be limited by ambiguities in the analytical interpretation of Aroclor mixtures extracted from environmental samples, the shift to the more highly chlorinated PCBs is consistent with known properties of PCB molecules. The more chlorinated F'CB forms are generally known to be more soluble in lipids, more resistant to degradation, and less volatile and therefore are expected to be more persistent in the environment than the less chlorinated forms. Capillary column gas
lhrk presented results from the monitoring of PCB concentrations in water from March through September 1977 at Schuylerville, Stillwater, and Waterford (22). PCB concentrations decreased from approximately 1.O pg/L during periods of low river flow (less than 100 m3k) to g e n e d y less than 0.2 pgl L during periods of intermediate flow (400-500 m'ls). The elucidation of overall trends in PCB transport is limited to the consideration of data from samples collected during periods of low to intermediate flow because most of the variability in high-flow subsets of annual PCB concentration data cannot be accounted for by river discharge. Assuming a lognormal probability distribution, there was a significant decrease in mean low-flow instantaneous PCB transport in the upper Hudson from43.7 mgls in 1979 to 18.5 mgls in 1980 (Figure 3). Overall, the mean FCB concentration in samples collected at Stillwater and Schuylerville from May through September each year declined from 0.68pglL in 1977 to 0.11 pg/L in 1982. A marked reduction in PCB transport is evident during periods of low to intermediate flow and in periods of high flow between 1977 and 1982. The decline in PCB transport during periods of river discharge below 400m3/s suggests that the supply of PCBs available for transport during periods of high discharge is diminished as well. Occasional analyses of 0.45-pm filtered and whole-water samples show that the largest PCB mass hansported during low flow is fdterable, whereas at high flow the largest mass is not. A qualitative comparison of chromategrams of extracts of filtmte and nonfilterable residue from river water samples shows that earlier eluting peaks, which correspond to the less chlorinated PCB congeners, are more prevalent in the filtrate samples (23). Chromatograms of whole-water samples collected from the river during periods of high flow tend to have larger proportions of later eluting peaks. Comparatively few water samples from the tidal Hudson have been analyzed for PCBs. Studies by Bopp, however, indicate a general concentration range of 0.1-0.2pg/L dissolved PCBs for the late 1970s (23). More recent samples show a range of 0.05-0.10 pg/ L dissolved PCBs (24). Forty discrete areas with average PCB concentrations above 50 pglg were identified based on extensive A-
ary, however, were substantially lower in 1981 than in 1976. Data from cores collected in the upper Hudson indicate that near-surface levels of F'CBs remain substantially elevated ( >200 pglg) in certain areas (17). These cores, however, were not suhsampled and analyzed with the resolution required to address deposition within the past five years or to assess PCB concentrations at the surface of hot spots.
FIGURE 3
Annual log mean PCB flux rate for river f l o e at Schuylervilk and stillwater, 1977-83b
chuylervilte "'
'3r
a :in . .
9 5
3 '
1978
1979
ment sampling of the upper Hudson. These areas, known as hot spots, were found primarily near the river shore. Large variations in sediment PCB concentration were evident in the upper Hudson River, although a general decreasing trend downriver was noted (6).Particle size and organic content appear to control variability in sediment PCBs in certain river reaches. Concentrations of 137Csand PCBs-the major deposition of both occurred in the 196Ck-a~ highly correlated in the up per and lower river (6). Sedimentation rates for hot spots calculated from I3'Cs data are approximately 2 c d y (6). Maximum PCB concentrations, which in certain areas exceeded l W p g / g , were generally found 15-30 cm below the surface of cores collected from hot
1980
.E
1983
Concentrations in fwb and water The concentration of waterborne PCBs could affect the concentration of PCBs in fish by direct partitioning and indirectly by influencing dietary exposure (25-29). To examine the relationships between PCB concentrations in water and fish, calculations were done for PCBs in various biological components and in water samples. Mean PCB concentrations in water samples were collected from Stillwater and Schuylerville during the summer months of 1977-82, when low flow and high temperatures were relatively constant. As shown in Figure 4,the water PCB concentrations correlate well with the PCB concentrationsin yearling pumpkinseed collected in the fall at Stillwater. Al-
FIGURE 4
Relaibnshins of summer mean PCB concentrationsin water and Iipid-basd'pcB concentrationsin fillets of whok yeading pumpkinseedwllected September 1977-83 at Stillwater'
spots.
A marked decline in PCB concentrations in the upper sections of core samples from the upper and lower river corresponds to the documented dec~easein PCB use at the GE facilities (6,23).This is confmed by comparison with a stratigraphic marker rovided by a 1971 peak discharge of I kl'Cs from a nuclear reactor at Indian Point in the lower estuary (15, 23). COmparisMl of the results of the 1976 and 1981 EPA sediment surveys is complicated by differences in extraction and data-reporting procedures. PCB levels in the upper sections of most of the cores collected in the estu-
200
Envimn. Sci. Technol., MI.19,NO. 8. 1985 659
though yearling pumpkinseed PCB concentrations appear to best reflect PCB levels in the water column, good correlations are also observed between other fish species and macroinvertebrates in the upper Hudson River. In the lower Hudson, the relationships between PCB concentrations in water and in fish may be influenced by shifts in home range size and feeding habits or by patchiness of exposure over an individual lifetime (21). Overall, these relationships support the arguments of a number of investigators (9, 21, 30, 31) that the contamination of pelagic (ocean) fish by PCBs or similar compounds is largely controlled by concentrations in the water column. The controlling function of these waterborne contaminants would be particularly evident in systems such as the Hudson River that were highly contaminated by recent direct discharges. However, it should be noted that the correlations between PCB concentrations in the water column and in fish are insufficient to reject some alternative hypotheses concerning the behavior of PCBs in the Hudson River ecosystem, particularly in the lower Hudson where contamination was less severe. One such hypothesis is that the PCB concentration in pelagic consumers of benthic-feeding organisms is largely controlled by PCB concentrations in surficial sediments. The correlationbetween fish and water PCB concentrations is consistent with this hypothesis, assuming that the water column concentrations reflect the level of contamination in surficial bed sediments. Assessing the processes that determine PCB concentrations in the upper Hudson appears to be more straightforward than studying those in the lower Hudson. In the upper Hudson, PCB desorption from the river bottom during low-flow periods will likely control water column concentrations and hence concentrations in fish. Characteristics consistent with the desorption process have been observed during periods of low flow, including the inverse relationship between PCB concentration and river discharge, the predominance of filterable rather than nonfilterable PCBs, and the transport of the more soluble and generally less chlorinated biphenyls. Runoff that results in the resuspension of PCB-contaminated bed sediments is relatively transient and infrequent during summer months and therefore should have little direct influence on PCB concentrations in upper Hudson River fish. Such events are likely to indirectly influence PCB concentrations in fish, however, by determining conditions at the sediment-wa660 Environ. Sci. Technol., Vol. 19,No. 8,1985
ter interface. The nature of the runoff determines the degree to which deposition of new sediment or scouring of old sediment changes conditions on the sediment surface. Overall, sedimentation and scouring in the upper Hudson are the result of several factors, including erosion and sediment transport in the watershed, bed sediment cohesion, ice formation and transport, routine channel maintenance dredging, and barge traffic, In the lower Hudson River and in estuarine transport, sediment and water interactions, volatilization, and the contribution of PCBs from sewage effluents influence the concentration of waterborne PCBs. The predominant feature of transport in the estuary is two-layer circulation, with flow in the upper layer generally an order of magnitude greater than freshwater input from the upper river. The summer’s low flow from the upper Hudson replaces a relatively small volume of the estuary. Therefore, low-flow PCB transport, which largely controls concentrations of PCBs measured in upper river fish, should have substantially less effect on PCB concentrations in lower river fish than intermediate- to high-flow PCB transport. Bopp evaluated the effects of suspended-sediment partitioning and volatilization on the distribution of PCBs in the lower Hudson River using data from chromatograms of extracts from summertime water samples collected at Troy and Poughkeepsie (32). To compare PCB component concentrations, chromatogram peak heights were normalized to the same suspended sediment concentration. Compared with the Troy samples, Poughkeepsie samples exhibited a 40% decrease in the less chlorinated biphenyls and virtually no loss in the more chlorinated biphenyls (25). The relative enrichment over time in the more chlorinated PCB congeners is expected, in light of their lower Henry’s constants. The elimination of the industrial PCB discharge, the stabilization of highly contaminated stream bank areas above the site of the former Fort Edward Dam, and the reduction in PCB releases from bed sediments have probably all contributed to the observed decline in PCB concentrations in fish. The consistency of this trend in the future will largely be a function of processes that control the release of PCBs from bed sediments in the upper river. It is difficult to determine from existing data the extent to which covering and mixing with cleaner sediments and the exhaustion of readily desorbable PCB congeners are responsible for the reduction in PCB release from the upper river. It might be assumed that im-
mediately following the reduction in the industrial PCB discharge the release rate that sustained high PCB levels in biota was independent of the relatively slow PCB resupply rates to the sediment surface.
Prognosis Bopp et al. stated that the processes largely responsible for the decline in surficial sediment concentrations in the lower Hudson are dilution and burial by relatively cleaner sediments recently derived from soils in the watershed (33). PCB half-lives in surficial sediments of the lower Hudson were calculated using data from selected cores in which a pronounced peak of PCB concentration was associated with a 1973 stratum identified by radionuclide dating. The maximum PCB concentrations and the concentrations in surficial sediments were used to calculate half-lives that ranged from 1.3 y to 3.8 y in five analyzed cores. They recognize the influence of the removal of the Fort Edward Dam and suggest that as a more “natural” PCB sedimentary process evolves, a 6-y half-life calculated for radionuclides in Hudson River surficial sediments will be approached. Any relaxation of the 1976 restrictions placed on commercial and recreational fishing in the Hudson River will depend on the FDA limitation and on the continued decline of PCB concentrations in fish. Although concentrations in striped bass have fallen since 1980 (90% of the legal-sized fish sampled showed PCB concentrations above the 5.0-ppm level; in 1982-83, 70% showed concentrations below 5 .O ppm), the recent enactment of a 2.0ppm tolerance level has resulted in the extension of the commercial fishing ban into Long Island Sound. It is unclear whether the extent to which the rapid decline in fish contamination between 1978 and 1979 is a function of the elimination of direct discharge, the stabilization of remnant deposits, and the response from accelerated PCB transport as a result of the removal of the Fort Edward Dam. The influence of those PCB sources on current levels of fish contamination likely is diminished (10). The consequence, as indicated by Thomann and %.John, should be a decrease in the rate of change (34). The differential processing in the environment of PCB congeners-in addition to the continued decline in PCB concentrations in fish-will impose greater difficulty with the use of Aroclor-based analyses to support future environmental management decisions. In light of the demonstrated differential toxicities within the array of PCB congeners (35-40), it may be appropriate to examine and reestablish standards
based on the more toxic PCBs. Additional investigations of the distribution of chlorinated dibenzofurans, an important class of PCB-associated compounds detected in Hudson River biota (41). are required. Whether or not remedial measures are implemented to hasten the recovery of the river, the necessity still exists to provide continued monitoring in conjunction with an effort to increase the understanding of the nature of F‘CB transport throughout the Hudson River.
Acknowledgment This paper was developed from data generated by several Hudson River PCB-monitoring programs, which were coordinated by the New York State Department of Environmental Conservation and funded primarily by the 1976 DEC-GE settlement agreement (File No. 2833) and by EPA grant C-36-1167-01. T h e opinions expressed a r e those of the authors and not necessarily those o f others associated with EPA, GE, o r this agency. We thank R. F. Bopp and H.J. Simpson of Lamont-Doherty Geological Observatory, R. Thomann of Manhattan College, R. Schmeder and C. Barnes of the USGS, 1. Carcich, M . Rafferty, and G. Mikol of the New York DEC for technical assistance, and w e thank all field and analytical personnel associated with the Hudson River PCB studies. Before publication this article was reviewed for suitability as an ES&T feature by David F. Armstrong, University of Wisconsin, Madison, Wis. 53706, W. Rudolf Seitz, University o f New Hampshire, Durham, N.H. 03824; and Richard E Bopp. Columbia University, Palisades, N.Y. 10964.
Reference ( I ) Nadeau, R. 1.; Davis, R. A. Bull. Environ. Conrom. Toxicol. 1916, 16. 436-44. (2) Horn. E. G.; Hetling, L.J.; Tofflemire. T. J. Ann. N. !I Acod. Sci. 1979, 320. 591609. (3) Spagnoli, 1.1.; Skinner, L. L. Pesric. Monir. 1. 1917, 11. 69-87. (4) Malcolm Pirnie. “PCB Hot Spot Dredging Program. Upper Hudson River. New York.” report prepared for the New York State Department of Environmental Conservation. Albany. N.Y., 1980. (5) ”Hudson River PCB Study Description and Detailed Work Plan”; Bureau of Water Research, Division of Water, New York State Department of Environmental Conservation: Albany. N.Y., 1977. (6) Tafflemire, T. 1.: Quinn, S. 0. “PCBs in the Upper Hudson River: Mapping and Sediment Relationships.” Technical Report No. 56; New York State Department of Environmental Conservation: Albany. N.Y.. 1977 (7) Helling. L. F : Horn. E.G : Tofncmm. T. 1 “Summary of Hudwn Rircr PCB Study Result$.“ Technical Rcmrt No 5 1 . Seu York State Demrtmeni of Environmental Conscrratian Alhsn). N Y , 1979 (8) “tnv#ronmentsl lmpacl Stalment on the Hudson Riser PCB Reclamation DemonaraAgency Region II: New York. N.Y., 1981. (9) Armstrong. R. W.; Sloan. R. J. “PCB Patterns in Hudson River ~~.~~ Fish 1~ .. Residenil ~~~
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(10) Sloan, R. J . et al. Bull. Environ. Conrom. Toxicol. 1983.31, 377-85. ( I I ) “Pesticides Analytical Manual”: Section 2 1 0 Food and Drug Administration: Washineton. D.C.. 1982: Vol. 1. (I2)-N& York University Medical Center. “The Biology of PCBs in Hudson River Zooplankton.’’ final report to the New York State Department of Environmental Conservation, Albany, N.Y.. 1982. (13) “National Handbook of Recommended Methods far Water Data Acquisition”: Office of Water Data Cwrdination. United States Geological Survev: Reston. Va.. 1977: Chapter-5. (14) O’Brien and Gere, Engineers. “PCB Analysis-Final Report,’’ prepared for the New York State Department of Environmental Conservation, Albany. N.Y., 1978. (15) Bopp. R. F. et al. Environ. Sci. Technol. 1981, 15, 210-16. (16) “PCBs in the Lower Hudson River Sediments-A Preliminary Survey”: Surveillance and Analysis Division. Environmental Protection Agency Region II: Edison. N.J..
(36) McKinney. J . D.: Singh, I? Chrm. B i d . Inrerurr. 1981.33, 271-83. (37) Goldstein. J . Ann. N. Y Acod. Sci. 1919, 320. 164-78. (38) Kimbrough. R. et al. Environ. Heolrh Pwspecr. 1978,24. 173-84. (39) Nebeker. A. V.: hrglisi, F. A.; DeFoe. D. L. Trms. Am. Fish. Soc. 1974. 103.56268. (40) Bush. 8.; Tbmasonis. C. F.: Baker. F D. Arch. Environ. Conrom. Toxicol. 1974. 2. 195-212. (41) Slalling. D.L., Columbia National Fisheries Laboratory. U.S. Fish and Wildlife Service, Columbia, Mo.. personal cammunication. April 4, 1979.
Mark t! Brown (1.) is ‘I r m e a ~ h.s
