B
I
€sGT
L
THE
CI:CLE AND FISH IN THE ADIRONDACK .
mercury (Hg) i n fish have been attrihuted to point sources of mercury generally associated with industrial discharge (1-3).In : recent years, there has been renewed interest in the transport and fate of mercury in the environment because of widespread reports of elevated concentrations of mercury in fish caught in remote lakes (4-8).
136 A Ennron. Sci. Technol.. Vol. 20. No. 3. 1994
Mercury in fish occurs almost entirely as methylmercury in muscle tissue (5, 91, where it is associated with protein sulfhydryl groups (10,1 1 ) . Ingestion of fish muscle is an important exposure pathway of mercury to humans. Methylmercury is highly toxic: it is thought to inhibit enzyme activity in the cerebellum, which is responsible for neuron growth in early developmental stages. Chronic exposure to organomercurials can result in mental retardation (12).As a result, the U S . Food and Drug Administration (FDA)has set an Action Level of 1 Kglg (wet weight) for concentration of mercury in fish. Fish containing concentrations of mercury above this level are considered to be hazardous for human consumption and cannot be sold in interstate commerce. Canada and several U S . states have developed consumption advisories of 0.5 pglg for mercury in fish. In the 198Os,the number of fish consumption advisories increased in several states and the province of Ontario. More recently, the number of advisories has increased because of the imposition of a blanket advisory covering more than 11,000 lakes in Michigan. This trend is probably the result not of an increase in the numbers of fish with elevated mercury, hut of increased monitoring and awareness of the problem. The mercury cycle in aquatic ecosystems is complicated because of the myriad of species and pathways (Figure 1). Our understanding of the biogeochemistry of mercury has increased markedly over the past 10 years with the development of clean protocols for the sampling and analysis of mercury (13,24). There is little confidence in measurements of aqueous mercury prior to 1985 because of the likelihood of sample contamination (151. Atmospheric deposition of mercury to lakes occurs largely as inorganic mercury (261, although inputs of methylmercury occur (17).Within oxygenated waters, Hg(I1) will complex with inorganic ligands (e.g., C1-, OH-), bind with dissolved organic carbon (DOC), or sorb to particulate matter. Mercuric ion can he reduced microbially to form elemental mercury [Hg(O)l.Most waters are oversaturated with respect to the solubility of atmospheric Hg(O),and Hg(0) is volatilized to the atmosphere (18). Within anoxic zones, mercury forms strong aqueous complexes with sulfide and precipitate as HgS. Within anaerobic environments or within anoxic microzones in aerobic environments, Hg(II1 can he converted to methylmercury. Sulfate-reducing bacteria appear to be important in the methylation of mercury (19, 20).Methylmercury may bind to DOC or be demethylated by microbial processes. Methylmercury is generally thought to be the form of mercury that bioconcentrates in fish. Gill and Bruland (21)reported a strong relationship between concentrations of organomercurials in lakes and mercury concentrations in fish. High concentrations of mercury in fish tissue have been reported in remote, low-ionic-strength lakes. Several studies have reported a correlation between fish mercury concentration and lake pH (16,5, 22, 23). A linkage between surface water acidification and fish mercury content has been inferred. Several mechanisms have been hypothesized to explain this phenomenon (81, including: increased inputs of mercury from atmospheric deposition, increased inputs of mercury from adjacent terrestrial ecosystems, increased partitioning of mercury to the water column in acidic waters, 0013-936W94/0927-136A604.50/0 @ 1994 American Chemical Sociew
'
\
low production of fish in acidic lakes, increased production of monomethylmercury with decreases in PH, decreased rates of demethylation with decreases in pH, and increased permeability of fish gills to methylmercury. Federal and state environmental protection and natural resource management agencies are particularly interested in mercury cycling in the environment. With the passage and subsequent implementation of the 1990 Clean Air Act Amendments, Congress directed EPA to develop a research agenda and schedule that would provide information on sources, transport, and fate and effects of mercury, including risks to human health and the environment. Title III (Hazardous Air Pollutants) of the amendments modifies Section 112 of the Act and provides a list of hazardous air pollutants (e.g., mercury) for control from major sources (those emitting 10 tons per year of a single pollutant or 25 tons per year aggregate). Lesser quantities may be considered for control based on their persistence in an ecosystem, hioconcentration factors, and health risk implications. Numerous studies are currently under way across the country that will provide information for specific Section 112 requirements. Provisions include deposition monitoring, source apportionment, and evaluation of public health and environmental effects. The assessment includes an evaluation of fish, wildlife, and other biota. In addition, a special report on mercury is being prepared by EPA. Information such as the results from the current study will complement effortsby the electric utility industry to characterize mercury emissions as well as the environmental fate and transport of mercury, and to perform risk analyses. It is expected that EPA will rely heavily on this and other work when it prepares the Section 112 mercury study and a more comprehensive Utility Hazardous Air Pollutant Study scheduled to be delivered to Congress in November 1995. Following receipt of the information provided by the regulated and scientific communities, EPA will make recommendations regarding the need for future mercury emission controls. The Adirondack region of New York has the most acidic lakes of any area in the United States (24).
c
FlGL
-
Schematic diagram summarizing the mercury cycle in lake ecosystems Inert Hg CH-Ha Outflow Stream Reactive Hg
Many of the lakes there are charac- (-60 cm/year). Within the Adironterized by low-ionic-strength water. dack Ecological Zone, there are Undoubtedly, many of these waters 2796 lakes and ponds covering >0.2 are naturally acidic because of in- ha in surface area. From 1984 to 1987, the Adironputs of organic acids (25-27).However, superimposed on naturally dack Lakes Survey Corporation acidic conditions are inputs of (ALSC) surveyed 1469 lakes within strong acids from atmospheric dep- the Adirondack Ecological Zone osition (28),which contribute to the (30,24).Physical, chemical, and biacidity of surface waters (25,29). ological data were collected on each Recently, Simonin et al. (23)inves- lake and its watershed. From this tigated concentrations of mercury detailed survey, a classification sysin fish tissue in 12 Adirondack tem was developed for Adirondack lakes and found relatively high con- lakes based on characteristics of hycentrations and increasing concen- drologic flowpaths, surficial geoltrations with decreasing pH. How- ogy, and concentrations of organic ever, these lakes were generally solutes (Le., DOC: 24,29, 31). neutral-pH waters with low concenFor the present study, 16 lakes trations of DOC. that represent many of the ALSC The objectives of this study were classes were selected. These lake to determine concentrations of total classes are thought to represent conand methylmercury in lake water ditions in which high concentraand concentrations of mercury in tions of mercury might occur in fish fish tissue in Adirondack lakes, and tissue (i.e., seepage lakes, acidic to evaluate mechanisms regulating lake classes such as thin till drainthe concentration of mercury in age lakes, and high-DOC lakes). These lakes are located throughout fish. the Adirondack Park, but many are Methods in the Oswegatchie-Black drainage The Adirondack region is a large area of the southwestern Adiron(2,400,000ha), predominately for- dacks. The Oswegatchie-Black waested area in northern New York tershed is characterized by many state (29).The bedrock material is low-pH and high-DOC lakes. Two of primarily granitic gneisses and the study sites are seepage lakes metasedimentary rocks. The moun- (Oregon Pond and North Pond); the tains and uplands are mantled gla- remainder are drainage lakes. Two cial till, thicker in the valleys and of the lakes (Sunday Lake and Halfbecoming progressively more shal- moon Lake) exhibit complete or low upslope. Soils of the region are nearly complete depletion of 0, in generally acidic Spodosols devel- the hypolimnion during summer oped from glacial till. The Adiron- stratification. The ALSC data base dack region receives large inputs of contains information on physical precipitation (-100 cm/year) and, factors, water chemistry, and fish as a result, has high stream runoff prey species that help interpret pat-
1 3 0 A Envimn. Sci. Technol., Vol. 28. No. 3, 1994
terns of fish mercury concentration. The percentage of wetland area was estimated from topographic maps of individual watersheds. These values should be considered as only approximate representations of wetland area. Subsequent analysis (Kretser, unpublished data) of areal photographs indicates that the wetland areas derived from topographic maps may be more representative of near-shore wetland areas and may under-represent upland wetlands. The yellow perch (Perm fluvescens) was selected as an index species because it is widely distributed throughout lakes in the Adirondacks, as well as the upper Midwest and southeastern Canada. From Sept. 16 to Oct. 29, 1992, 977 yellow perch were collected from the 16 study lakes. Fish were captured using variable-mesh experimental gill nets and Alaska-style net traps. Nets were fished until a minimum of 60 yellow perch were collected from each lake. Live, undamaged perch, representative of the size distribution in the catch, were selected for analysis. Length and weight measurements were obtained from each selected fish, and scale samples and opercular bones were removed for age and growth analysis. Fish were individually wrapped in aluminum foil, placed in Ziploc bags, and kept on ice until they could be frozen (within 4-8 h after collection). After the ages of all perch were determined, utilizing both scales and opercular bones, a sample of 30 fish, representative of the age distribution, was selected for tissue sampling for mercury analysis. A section of the dorsolateral muscle tissue was removed from the same location on each fish using the protocol described by Gloss et al. (32). Tissue samples 11.0 g wet weight were frozen intact, while samples >1.0 g wet weight were first homogenized with a stainless steel tissue homogenizer. All samples were kept frozen until analyzed for mercury. Mean annual growth rates [G = log(Wt)-log(Wl)/t-1, where W = weight in g, t = age in years] were determined from weights at ages obtained from back-calculated lengths using opercular bones [In (total length, mm) = 3.17 + 0.88* In (opercular length, mm), N = 931, 3 = 0.961 and length/weight relationships for individual lengths. Water samples were collected from the lakes between Oct. 15 and 22,1992. Clean techniques were fol-
lowed during all phases of sample collection and handling. Lake water was collected by grab-sampling over the side of a nonmetallic boat into 1-L Teflon bottles for mercury analysis and into 1-Lpolypropylene bottles for the analysis of major solutes. Care was taken to avoid sampling water over which the boat had passed. Sampling personnel wore full clean-suits with shoulderlength plastic gloves and collected water from about 0.25 m below the lake surface. Sampling bottles were opened and closed at depth to avoid sampling the surface film, and were rinsed three times with water prior to collecting the final sample. The bottles were hermetically sealed and double-bagged immediately after sample collection. Upon transport to the laboratory, samples were filtered through an acid-cleaned 0.2-ym disposable nitrocellulose filter for analysis of total dissolved mercury. For analysis of total and total dissolved mercury, samples were first oxidized with BrC1. After oxidation, samples were pre-reduced with NH,OH-HCl, reduced further with SnCl,, purged to Au traps, and thermally desorbed as Hg(0) with He carrier gas for detection by cold vapor atomic fluorescence spectrometry (CVAFS). Total methylmercury was processed by first extracting samples from a HClI KC1 matrix into CH,Cl, followed by back extraction into pure water (by solvent evaporation). Determination of methylmercury was accomplished by aqueous-phase ethylation with NaB(C,H,),, cryogenic gas chromatograph separation, and CVAFS detection. Bloom (33) provides details of the procedure used to fractionate aqueous samples for mercury. The water samples collected were also measured for major water chemistry parameters using the procedures summarized i n Driscoll and van Dreason (32). Water chemistry results The lakes evaluated in this study exhibited diverse physical characteristics and water chemistry, and represent 1 2 of the ALSC lake classes. The lakes contain generally acidic, low-ionic-strength waters. Values of acid-neutralizing capacity ranged from below 0 to above 200 keq/L, with pH values from below 5 to near 7.0. The study lakes also covered a range of DOC concentrations (from 3.4 to 26.5 mg C/L). Lake DOC concentrations were influenced by the presence of near-shore wetlands within the drainage basin
[DOC concentration (mg C/L) = 1.42" YO wetland t 0.56, 12 = 0.88; where % wetland is the percentage of the total watershed area that is near-shore wetlands], Consistent with the sundry physical and chemical characteristics were diverse concentrations of total mercury. The seepage lakes (North and Oregon Ponds) had the lowest concentrations of total mercury of the study lakes, less than 1 ng/L. The concentrations of total mercury in drainage lakes ranged from below 1 ng/L to above 5 ng/L. Most of the total mercury was in the dissolved fraction (mean dissolved Hg/total Hg = 0.61), although there was considerable lake-to-lake variability in the fraction of particulate mercury. There was no relationship with the fraction of dissolved mercury and water chemistry parameters, such as pH or DOC concentration. Considerable variability was also evident in concentrations of methylmercury (0.068-0.61 ng/L). The seepage lakes (North and Oregon Ponds) showed low concentrations of methylmercury. Lakes with anoxic hypolimnion during summer stratification (Sunday Lake and Halfmoon Lake) had very high concentrations of methylmercury, consistent with the formation of methylmercury under anaerobic conditions. In the Adirondack lakes studied, there was generally a good relationship between concentrations of total methylmercury and total mercury for oxic lakes [methylmercury (n /L) = 0.1* total Hg (ng/L) - 0.033, = 0.841. Therefore, total methylmercury was about 10% of total mercury in most Adirondack lakes. An exception was evident for the lakes with anoxic hypolimnion, which had about 20% of total mercury as total methylmercury. In the Adirondack lakes, there was a pattern of increasing concentrations of both total mercury and total methylmercury with decreasing pH. Moreover, for a given pH value, lakes with DOC concentrations > 6 mg C/L had higher concentrations of both total mercury and total methylmercury than did lakes with DOC concentrations 0.05) age effects between lake comparisons of mean mercury concentrations. Further increases in fish me] cury above age 5+ probably reflect shift to piscivory. The latter i n crease in mercury concentration c older age fish occurred at a length ot approximately 2 0 0 mm, above which piscivory or cannibalism is common to yellow perch populations (34). In Oregon Pond, concentrations of fish mercury increased up to age 6+ and declined thereafter. This unusual pattern may be partly the result of a lack of fish prey species in this pond and high variability in growth rates of older fish. For example, mercury concentrations in age 9+ perch were inversely related to growth rates [fish Hg ( g/g) 0 80 1.87Zagrowth rate, 0.i6,'p 0.00171, and mercury concentrations in perch age 7+ to IO+ were inversely related to body weight [fish Hg (pg/g) = 0.45 - O.OOl*weight (g], f = 0.45,p = 0.00181. These relationships suggest that growth dilution (Le., rate of muscle tissue elaboration exceeds rate of mercury uptake in food) is responsible for the decline in mercury concentration of older, faster growing perch in the Oregon Pond population. Unlike other studies (21),none of the simple regressions between con-
J=
I
'IGURE 3
Concentrations of mercury in the muscle tissue of different age classes of yellow perch in Adirondack study lakes, except Oregc Pond, and lakes from the Upper Peninsula of Michigan (5)
. m
11.0
A
Adirondack lakes Upper Peninsula, MI
..............~~~~~~~~~~
2.
centrations of mercury in age 3+ to 5+ perch and aqueous measurements of pH, DOC, and methylmercury was significant (p> 0.05)when the high-DOC (26.5 mg C/L) Rock Pond was included in the analysis. Excluding Rock Pond, significant ( p < 0.05) regressions were obtained between fish mercury and methylmercury concentrations in the water column [fish Hg (pg/g) = 0.35 + 0.58*methylmercury (ng/L), f = 0.321, and pH [fish Hg (pg/g) = 1.61 - 1.19*pH, ? = 0.371 and DOC [fish Hg (pglg] = 0.13 + 0.067*DOC (mg C/L), f = 0.29; Figure 41. The only water chemistry parameter significantly correlated with fish mercury when all 16 lakes were
140 A Environ. Sci. Technol.. Vol. 28, No. 3, 1994
included was total dissolved AI [fish Hg (pg/g) = 0.27 + 0.001"total diss A1 (pg/L), f = 0.59; Figure 51. Total dissolved A1 tends to be highest in low-pH lakes with high DOC (35)and appears to be a better indicator of fish mercury concentrations than either pH or DOC alone. This observation suggests that fundamental hydrologic and geochemical processes controlling the transport and solubility of A1 also influence the bioavailability of mercury in these lakes. Hypolimnetic anoxia is another factor that may influence mercury bioavailability in Adirondack lakes. For example, concentrations of mercury in age 3+ to 5+ yellow perch
Sunday Lake and Halfmoon Lake. In multiple regression analysis, mean mercury concentrations for age 3+ to 5+ yellow perch increased with increasing total dissolved A1 and decreased with increasing DOC. Although aqueous total methylmercury concentrations were higher in lakes with high DOC concentrations (Figure Z ) , bioavailahle methylmercury appears to be regulated primarily by the extent of mercury binding with organic ligands. Aluminum may compete with methylmercury for organic binding sites, thus leading to greater bioavailability of methylmercury in lakes with high AllDOC ratios [fish Hg (pglg) = 0.01 x Al/DOC (pg Al/mg C) + 0.21, ? = 0.731.
FIGURE 5
Concentrations of mercury in muscle tissue of age 3+ to 5+ yellow perch as a function of dissolved AI concentration in study lakes
- 0.8 - 0)
3
$
e
0.7
0.6
-
0.5
-
2=
m
0.4 : 5 0.3 -
E
a
0.2
-
were high in both Sunday Lake and Halfmoon Lake, lakes with anoxic hypolimnion and high concentrations of methylmercury in the water column. In Adirondack lakes, concentrations of mercury in age 3+ to 5+ yellow perch increased with increasing concentrations of DOC (Figure 4) and percentage of near-shore wetlands in the drainage basin [fish Hg (pglg) = 0.08*% wetland + 0.19,Z = 0.671, without considering the highly dystrophic Rock Pond. The Rock Pond data suggest that with increases in DOC concentration at some value above 8 mg C/L, concentrations of fish mercury decrease. The bioconcentration factor (BF)
of methylmercury is defined as the ratio of methylmercury concentration in fish tissue to the methyl mercury concentration in water. For age 3+ to 5+ yellow perch, the log BF ranged from 5.73 to 7.03. The log BF decreased significantly with increasing concentrations of DOC, but showed no significant ( p > 0.05) pH effect. For given concentrations of DOC, the presence or absence of potential fish prey species also significantly influences the methylmercury BF [log BF = 6.1 0.044*DOC (mg CIL) + 0.35*prey presence/ absence, 3 = 0.481. For the Adirondack lakes studied, the log BF was lowest in dystrophic Rock Pond and the lakes with anoxic hypolimnion,
-
Discussion Like other remote lake districts in eastern North America (5, 221, concentrations of mercury were elevated in fish tissue in Adirondack lakes, with patterns of increasing mercury concentrations with decreasing pH. Concentrations of mercury in muscle tissue of yellow perch obtained from remote Adirondacks lakes were higher than values reported in the detailed study of lakes from the Upper Peninsula of Michigan (5;Figure 3). For example, length-adjusted least squares mean mercury concentration in muscle tissue of age 3+ to 5+ yellow perch obtained from 14 Adirondack drainage lakes (0.46 pg/g) was significantly higher ( p < 0.004) than age 3+ to 5+ yellow perch mean mercury concentration from 1 2 drainage lakes (0.27 pg/g) in the Upper Peninsula of Michigan (5). However, there was no significant difference ( p = 0.65) in the adjusted least squares means (Adirondacks = 0.38 pg/g; Michigan = 0.36 pglg) when regional differences in the total Al/DOC ratio were accounted for by covariance analysis (3= 0.76). Regional comparison of least squares mean AllDOC ratios, adjusted for pH, indicated that the ratio was significantly ( p < 0.004) higher in the Adirondack drainage lakes. In the Adirondacks, 26% of the yellow perch caught exceeded the 0.5 pglg Action Level, and 7% exceeded the FDA Action Level of 1.0 pg/g. Additionally, at least one perch with mercury concentrations exceeding the 0.5 pg/g level was found in 14 of the 16 study lakes, and at least one perch exceeding the 1.0 pglg level was found in 9 of the 16 study lakes. It is not clear why mercury con-
Environ. Sci. Technol.. Vol. 28. No. 3,1994 141 A
centrations are high in yellow perch in Adirondack lakes in comparison to other lake districts in eastern North America. Concentrations of total mercury in Adirondack lakes were also generally higher than values reported for other remote lakes in the literature (Table 1).The highest concentrations of total mercury measured for Adirondack lakes were comparable to concentrations reported for urban lakes or lakes with a point source of mercury from mining or industrial activity. The most obvious factor regulating the concentration and availability of both total and methylmercury in Adirondack lakes is DOC. A number of investigators have reported relationships between mercury and concentrations of DOC or color in surface waters (36, 37). However, correlations between DOC concentrations and fish tissue mercury have been inconsistent. Concentrations of DOC explained a significant amount of the variation of mercury in lake trout in Ontario (4). Likewise, Haines et al. (8) observed a positive correlation between lake color and concentrations of mercury in perch in the former Soviet Union. In contrast, Grieb et al. ( 5 ) reported that the mercury content of yellow perch decreased with increasing DOC concentrations in seepage lakes. The results of our study suggest that DOC plays a complicated role in the transport and bioavailability of mercury in lake ecosystems. The transport of total and methylmercury to Adirondack lakes seems to be linked to DOC, which is released from wetlands within the basin. This pattern has also been observed for lakes in Sweden (38).Therefore, DOC concentrations seem to he important in regulating lake concentrations of both total and methylmercury, and ultimately the supply to fish. On the other hand, DOC appears to bind with methylmercury, limiting its hioavailability. This conflicting role of DOC is shown by the increase in fish mercury concentrations with increasing DOC up to concentrations of about 8 mg C/L followed by lower concentrations of mercury in yellow perch caught from highly dystrophic Rock Pond (DOC = 26.5 mg CIL; Figure 4), and the observed decreases in the BF of methylmercury with increasing DOC. In addition, inputs of other metals, such as Al, that complex with DOC appear to alter the binding of mercury with organic ligands,
increasing its bioavailability. This process is particularly relevant for lake districts, such as the Adirondacks, that have been impacted by acidic deposition and exhibit elevated concentrations of Al. In addition to DOC concentration, other factors such as lake pH and A1 concentration, anoxic hypolimnion, fish age, and food sources appear to be important in the regulation of mercury concentrations in fish tissue. These myriad factors undoubtedly contribute to the weak relationship between methylmercury in lake water and mercury concentrations in fish tissue. Elevated concentrations of mercury in fish tissue may have implications for higher trophic levels within the Adirondack and other remote regions. McIntyre et al. (39)investigated mercury concentrations in eggs of the common loon (Gavia immer). They found that concentrations were higher in eggs collected in the Adirondacks than in other lake districts in New Hampshire and Saskatchewan. They reported very high mercury concentrations in common loon eggs from Stillwater Reservoir in the Adirondacks (1.58pglg), near levels found to induce reproductive problems in mallards (Anasplatyrhynchos: 40). Although our study provides important data on concentrations of mercury in fish tissue in Adirondack lakes and factors that influence this accumulation, critical information i s missing for t h e management of this important water quality problem. First, there is
142 A Environ. Sci. Technol., Vol. 28. No. 3, 1994
little time-series information on concentrations of mercury in the Adirondacks. McIntyre et al. (39)reported that concentrations of mercury have declined in common loon eggs from 1978 to 1986; however, there is no historical information on trends in mercury in water or fish in the Adirondack region. Second, it is unclear whether the sonrce of mercury in the Adirondacks or other drainage lakes in eastern North America is atmospheric deposition, or whether the mercury is derived from mercury-bearing minerals in soil. Fitzgerald and Watras (15)conducted a mass balance for a seepage lake in Wisconsin and reported that inputs of mercury were largely the result of atmospheric deposition. In an earlier study, Bloomfield et al. ( 4 1 ) developed a mass balance on mercury for Cranberry Lake in the Adirondacks and found that lake mercury was largely derived from within the lake watershed. Note, however, that watershed sources could still represent atmospheric deposition in a watershed followed by remobilization to drainage waters. The strong relationship between DOC and water column mercury observed in our study could support either perspective (Le., atmospheric or mineral sources). Moreover, wetlands play an important role in the transport of mercury to lake ecosystems. However, the ultimate source of lake mercury (atmospheric vs. mineral release) and the way in which inputs have changed over time is unclear, resulting in a critical uncertainty for
m a n a g e m e n t decisions on controls
of atmospheric emissions of mercury through t h e Clean A i r Act Amendments of 1990.
Acknowledgments This study was funded by the Empire State Electric Energ Research Corporation. the New Y o r i State Energy Research Development Authority, and the Electric Power Research Institute. W e thank Walt Kretser and rim Gallagher of the Adirondack Lake Survey Corporation for help with fish collection and data analysis, Carl Watras for help in sample collection, and Nick Bloom for help in sample analysis. We also appreciate the assistance of Sean Tenney, Wei Wang, Dawn Long, a n d Kim Postek. This is contribution No. 128 of the Upstate Freshwater Institute.
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Carl L. Schofield is n fishery biologist and senior rpsmrch associate in the Deporiment of Natural Resources a t Corne11 University. His research has focused on lake acidification effects on fish populations in the Adirondock region of New York state.
Charles T.Driscoll is distinguished professor of civil a n d environmental engineering a t Syracuse University. His research interests include element cycling in terrestrial. wetland. a n d aquatic ecosystems, and environmental q u a l i t y modeling.
Ronald K. Munson is a senior engineer a n d project managerfor Tetra Tech, Inc. He holds a n M.S. degree from Brigham Young University. His research interests include mercury cycling a n d acid deposition modeling, a n d evoluotion of nonpoint sources of pollution
(35) Driscoll. C. T. In The Environmental Chemistry of Aluminum: Sposito. G..
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Pollut. 1990, 650, 255. (23) Simonin. H. A. et al. In Trace Sub-
stances in the Environment: Lewis Publishers: Chelsea, MI, in press. (24) Baker. 1. P. et al. In Adirondack Loke Survey: An Interpretive Analysis of Fish Communities and Water Chemistry, 1984-87; Adirondack Lakes Sur-
Cheng Yon is research assistant and gmduate student in the Depariment of Civil a n d Environmental Engineering at Syracuse University. He holds a B.S. degree from Nanjing University. His research interests include heavy metal contamination in natural water systems
and soil.
John G. Holsapple is the administrator of waterqualilv progmms for the Empire State Electric Energy Research Corp. He holds a n M.S. degree from the University of Massachusetts. His research interests include the relationship between electric generation activities a n d aquatic ecosystems.
Environ. Sri. Technol.. Vol. 28. No. 3, 1994 143 A
