Envlron. Sei. Technol. 1982, 16, 459-464
Accumulation by Fish of Contaminants Released from Dredged Sedimentst James G. Seelye,* Robert J. Hesselberg," and Michael J. Mac
Great Lakes Fishery Laboratory, U.S. Fish and Wildlife Service, Ann Arbor, Michigan 48105
rn Inasmuch as the process of dredging and disposing of dredged materials causes a resuspension of these materials and an increase in bioavailability of associated contaminants, we conducted a series of experiments to examine the potential accumulation by fish of contaminants from suspended sediments. In the first experiment we compared accumulation of contaminants by yellow perch of hatchery and lake origin and found that after 10 days of exposure to nonaerated sediments, fish of hatchery origin accumulated PCBs and Fe, while fish of lake origin accumulated As, Cr, Fe, and Na. Two additional exposures were conducted to evaluate the effects of aerating the sediments prior to measuring bioavailability of associated contaminants. Fish of hatchery origin exposed to nonaerated sediments for 10 days accumulated PCBs and Hg, while fish of hatchery origin exposed to aerated sediments for 10 days accumulated PCBs, DDE, Zn, Fe, Cs, and Se. These results demonstrated not only the potential for uptake of contaminants by fish as a result of dredging but also the potential utility of fish bioassays in evaluating proposed dredging operations. In dredging activities in the Great Lakes, more than 10 million cubic meters of sediment are moved each year, and large amounts of these sediments are resuspended in the water column during both dredging and disposal of dredged material. Frequently these activities take place in harbors and river mouths that are important rearing grounds for fishes. Since sediments in these areas are often contaminated with toxic substances, persistent chemicals may be accumulated by fish indirectly through the food web or directly from exposure to resuspended sediments. In this study, we simulated the conditions fish would encounter during dredging to ascertain whether chemical pollutants associated with bottom sediments such as PCBs, DDE, dieldrin, Cr, Ni, Se, and Zn are accumulated by fish during exposure to a slurry of contaminated sediments. In addition, the results of this study were used to identify factors that should be considered in designing bioassays to determine sediment quality. Methods and Materials This study was divided into three experiments, each involving the exposure of yellow perch (Perca flavescens) for 10 days (the approximate time required for a typical hopper-dredging operation in a Great Lakes harbor and the time period specified for bioaccumulation studies in the Implementation Manual for Section 103 of Public Law 92-532,1977) ( I ) . In the first experiment, fish of hatchery and lake origin were exposed to a suspension of nonaerated sediments; in the second, fish of hatchery origin were exposed to a suspension of nonaerated sediments; and in the third, fish of hatchery origin were exposed to a suspension of aerated sediments. Chemical data on sediments in frequently dredged areas of the Great Lakes were supplied in early 1977 by the US. Contribution No. 586 of the Great Lakes Fishery Laboratory. *Presentaddress: Hammond Bay Biological Station, Millersburg, MI 49759.
Army Corps of Engineers (USACE) district offices and US.EPA Region V (Chicago). We collected samples of sediments at the mouth of the Saginaw River near navigational buoy 31 in Saginaw Bay, because the sediments there contained a number of organic contaminants and metals at elevated levels and the area was frequently dredged to maintain the navigation channel. Sediments collected at this site by the US.Army Corps of Engineers in 1976 were relatively fine grained (80% smaller than 0.067 mm, 50% smaller than 0.014 mm, and 20% smaller than 0.007 mm, unpublished data USACE). In addition, juvenile yellow perch' from that area could be collected more readily than those from other areas. Sediment Collection. About 0.5 m3 of sediment was collected from the 8-m water depth in August 1977 and again in June 1978. We collected sediments with a Ponar grab sampler and sifted them through a 0.5-cm screen (to remove shells and other large objects) directly into a polyethylene-lined stainless steel box with an airtight lid. During collection and handling, we minimized contact of the sediments with air and stored the sediments under nitrogen to eliminate further oxidation. The sediment was cooled with ice, transported to the Great Lakes Fishery Laboratory, and stored at about 4 "C in the airtight containers. Test Organisms. Yellow perch were used for these experiments because of their importance as commerical and sport fish and their ubiquitous distribution in the Great Lakes. Juvenile yellow perch are found in near-shore areas, harbors, and river mouths where dredging occurs. Fish were obtained from two sources for the August 1977 exposure study. About 300 young-of-the-year yellow perch were seined from shallow water near a small unnamed island immediately northeast of the Saginaw River mouth, and lo00 hatchery-reared young-of-the-year were obtained from the National Fishery Research Laboratory, La Crosse, WI. In June 1978, 5000 yearling yellow perch were obtained from the La Crosse laboratory. A summary of lengths and weights of fish used is given in Table I. Description of Exposure System. We employed a pulsed addition of sediment with a continuous flow of water for exposing the fish to sediment (Figure 1). Each of the three experiments included two exposure and two control tanks. Sediment was placed in a 12-L fiberglass cylinder equipped with an electric motor-driven acrylic stirrer. A continuous flow of nitrogen gas was passed over the sediment in this covered cylinder, except during the experiment conducted in 1978 with aerated sediments. A 40-cm length of 3.75-cm i.d. PVC pipe was attached to the bottom of the cylinder at an upward angle 30" from horizontal. We adjusted sediment consistency by adding degassed distilled water until the sediment freely flowed into the PVC pipe. Sediment was metered out of this pipe by using an acrylic spiral auger connected to a variablespeed motor controlled by a cam timer. Sediment, drawn from the pipe by the auger, fell into a cup attached to a counter-bdanced lever that activated a microswitch after about 25 g of sediment was deposited in the cup. Activation of the microswitch stopped the rotation of the auger, opened a solenoid on a water line allowing water to rinse the sediment from the cup into a second fiberglass cylinder,
Not subject to US. Copyright. Published 1982 by the American Chemical Society
Environ. Sci. Technol., Voi. 16, No. 8, 1982
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Table I. Mean Weights, Water Content, and Lengths (Postexposure) of Fish Used in Sediment Exposure Studies (One Standard Error in Parentheses) postexposure ~~
preexposure"
controls
water content, exp lC hatchery lake exp 2d nonaerated sediment exp 3d aerated sediment
wt, g
%
0.87 (0.04) 5.25
79.0 76.6
3.77 (0.16) 4.46 (0.19)
length, mm
%
NMb NM
0.83 (0.03) 4.29 (0.41)
73.9 74.1
68.0
76.5 (1.4)
4.48 (0.32)
67.3
77.5 (1.7)
4.65 (0.36)
NM = not measured.
Table 11. Chemical Characteristics of Processed Great Lakes Fishery Laboratory Water. Mean Value for 3 Samples Are Given in mg/L (Except pH)" characteristic mean 7.7 PH alkalinity (CaCO,) 354 hardness (total) 442 chloride 48.2 sulfate 100 TOC 3 nitrate and nitrite 0.05 TKN 0.645 ammonium 0.02 silica 0.03 sodium 23.8 potassium 1.69 manganese
