(18) Lippman, M., in “Air Sampling Instruments for Evaluation of Atmospheric (?ontaminants”, 5th ed., American Conference of Government Industrial Hygienists, Cincinnati. 1978, Section G.
Received f o r recieu Octobcr 29, 19i.9).Acccjptcd J a n u a r y 21, 1980. This material i s based upon I ! ork irhich ic’as partiaily supported h x t h e A‘ational Science Foundatir~niiridcr Grant ,Yo. E.V(;77-0.1667.
Trace Element, Radionuclide, and Polynuclear Aromatic Hydrocarbon Concentrations in Unionidae Mussels from Northern Lake George Merrill Heit”, Catherine S. Klusek, and Kevin M. Miller Environmental Measurements Laboratory, U.S. Department of Energy, New York, N.Y. 10014 ~
Analyses of the soft tissues of three species of Unionidae mussels collected from northern Lake George, N.Y., showed t h a t these organisms concentrated Cd, Cu, Hg, Se, and Zn above t h e levels found in the sediment from which they were collected. Chromium, Ni, and P b occurred in the tissues at the concentration levels of the sediment, while As and Sn were found to be only a small fraction of the levels in sediment. The polynuclear aromatic hydrocarbons, phenanthrene, fluoranthene, pyrene, I-methylpyrene, perylene, and dibenzothiophene, were detected in some but not all of t h e mussel samples. Benz[a]ani,hracene, benzo[a]pyrene, and dibenzacridine were not found in any of the mussels. The mussels were found to accumulate radionuclides believed to have been deposited following the Chinese weapons tests of 1976 and 1977. Naturally occurring principal y-emitting radionuclides in the ‘W a n d ’j2Th series as well as 40K were not detected in the tissues. T h e use of pelecypods, such as the intertidal mussel M j ~ t i lus, to study t h e occurrence and bioavailability of metals, hydrocarbons, and transuranic elements in marine environments is well known (1-3). However, few reports on the levels of these substances in freshwater bivalves are available. Most of t h e studies which have been presented in the literature are concerned with the levels of a few trace elements in mussels collected from moderately polluted environments ( 4 - 7 ) . In this study we have looked a t three classes of trace substances released into the environment by energy-related activities: trace elements and polynuclear aromatic hydrocarbons (PAHs) from the incomplete combustion of fossil fuels (8,9) and radioactivity from various sources. I t was our aim to determine which of these substances are available to these filter-feeding members of the freshwater food web and t o observe t o what extent they are bioaccumulated under socalled “natural” conditions in which there is little stress from energy-related pollutants other than those deposited in the ecosystem by long-range atmospheric transport. Materials and Methods
Sampling Location. Three species of freshwater mussels were collected from Hearts Bay, northern Lake George, during October 1977. T h e lake is located in t h e eastern Adirondack Mountains of t h e New York State Adirondack Park. Lake George is 5 2 krri long and is divided essentially into two lakes with approximately equal volume basins by a natural constriction termed t h e “Narrows”. T h e southern basin is more eutrophic, receiving some local anthropogenic input from the resort area located at this end of the lake. T h e northern basin is essentially oligotrophic, receiving little input from local sources (10). I t has been stated t h a t the sediments presently being deposited in the northern basin of the lake are quite similar t o those deposited in the past by glacial action (11). We have previously presented evidence indicating t h a t the input of PAHs into the northern portion of t h e lake appears t o be t h e result of long-distance atmospheric transport of combustion-derived materials (8).
Mussel Species. The species of mussels collected, in order of abundance, were L a m p s i l u s radiata, Elliptio c,omplanatus, a n d A n o d o n a t a g r a n d i s . All of the organisms were gathered in about 3 m of water by divers and frozen shortly after collection. T h e sediment in which they were collected was grey in color, somewhat gritty, and composed of a mixture of‘fine sand and silty clays. Analysis. T h e mussels and sediment were analyzed for trace elements and polynuclear aromatic hydrocarhons by contractor laboratories. Radionuclides in the mussels were measured in our laboratory. Trace E l e m e n t s . Fifteen-eighteen soit tissues from each species were separately analyzed for trace elements. The individual tissue weighed between 2 and 12 g (wet weight). Each sample was homogenized by hand using a Teflon spatula and then dried a t 60 “C. The percent moisture was determined. T h e samples were wet ashed with concentrated nitric acid in acid-precleansed Teflon beakers over a hot plate. After 6-8 h, t o complete digestion, the samples were taken to near dryness, redissolved in 10%nitric acid, and diluted to a known volume. T h e samples were analyzed for As, Cd, Cr, Cu, Ni, Se, S n , and Zn. Sediment samples to be analyzed for the same elements were digested in a similar manner except that concentrated hydrofluoric and perchloric acids were used. Sediment and tissue samples to be analyzed for Hg were wet-digested overnight in Pyrex beakers in a water bath at 60 “C, using sulfuric and nitric acids. J u s t prior to analysis the samples were further oxidized by the addition of potassium permanganate and potassium persulfate. All of the analyses were performed by atomic absorption spectrophotometry (AAS); however, depending upon the elements to be analyzed, different procedures were used. Cadmium, Cu, and Zn were analyzed by flame AAS, Hg by cold vapor flameless AAS, and Cr and Ni using a heated graphite furnace and deuterium background corrector. Arsenic and Se were also analyzed by graphite furnace AAS; however, the sample aliquots were first converted to hydrides using oxalic acid and sodium borohydride. The metal hydride was purged into the graphite furnace with helium gas. R a d i o n u c l i d e s . The soft tissues of 3 2 Elliptio mussels were sealed collectively in a 210-cm:j Teflon-lined aluminum tuna can and analyzed by y spectroscopy. Owing to the limited amount of mussel tissue and sediment available, only the E l l i p t i o species was analyzed for radionuclides. T h e sample was counted for 4000 min with a 130-cm:’ Ge(Li) y - r a y detector in conjunction with a 4000-channel analyzer and a programmable calculator (12). Polynuclear Aromatic Hydrocarbons. Twelve composite soft tissue samples consisting of 12-50 mussels (Elliptio and Larnpsilus), weighing between 50 and 200 g wet weight, were homogenized and saponified with 4 N sodium hydroxide at 90 “C for 2 h and then extracted three times with ether. T h e ether extracts were combined, dried on magnesium sulfate, concentrated on a modified Kuderna-Danish apparatus, and diluted with methylene chloride. The concentrated ether extract was then fractionated by BioReads 5x8 gel permeation chromatography and the aromatic fraction analyzed by
This article not subject to U.S. Copyright. Published 1980 American Chemical Society
Volume 14, Number 4, April 1980
465
Table 1. Trace Element Levels and Concentration Ratios for Lake George Mussels no. of samples
Cd
As
A.
Cr
cu
Hg
Ni
Sn
Se
Pb
Zn
Trace Element Concentration in Mussels, Sediment, and Water
mussels, pg/g dry wt E. cornplanatus L. radiata A. grandis
sediment, pg/g dry wt
18 18 15 2
0.3f0.2 9 f 4 0.2f0.2 9 f 5 0.3f0.21 0 f 3 3.1f 1.3
4
water, ng/ga
2
-
3f3 2f2 3f3
9 f 3 0.440.23 f l 1 2 f 5 4 f 2 1 8 f 4 0.3f0.1 3 f 1 9 f 4 3 f 1 1 4 f 5 0.340.25 f 3 1 6 f 9 2 f l 0.22f 0.06 0.3f0.3 4 4 2 4fl0.03f 4fl 8f7b 0.01
