ISSN:0730-7268    

DOI:10.1002/etc.5620090701

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractLong‐range atmospheric transport of pollutants affects the chemistry of heavy metals in natural waters in several ways. First, the direct atmospheric supply of some metals to lakes and their catchments may add strongly to the total burden of these metals in the lake ecosystems. Second, the acidity of the precipitation may enhance the metal fluxes by dissolution of metals originating from mineral material in the catchment or previously supplied by atmospheric deposition and fixed to surface soil or sediment. Furthermore, the acidification of surface waters interferes strongly with the speciation of the metals in the water. The southern part of Scandinavia is considerably influenced by long range atmospheric transport from other parts of Europe. The present paper is a review of recent work in this region related to the occurrence and chemical behavior of lead, cadmium and other trace metals in natural surface waters, with emphasis on the supply from atmospheric deposition. The impact of acidification on the mobility and chemical speciation of the metals is briefly discusse

ISSN:0730-7268    

DOI:10.1002/etc.5620090702

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThree lakes and catchment runoff in the Lake Gårdsjön watershed on the Swedish west coast have been sampled for methylmercury during one year. The analyses indicated that high outputs of methylmercury were present during autumn in flushing water systems with short retention time, whereas smaller outputs and variations occurred in lake waters with longer retention time.Thus, methylmercury concentration were measured as 0.16 to 0.41 ng/L (humic rich lake), 0.12 to 0.26 ng/L (limed lake),<0.1 ng/L (acid clearwater lake with long retention time) and 0.13 to 0.28 ng/L (acid runoff from a forest).A flux estimate from one forested catchment (3.6 ha) gave a yearly output of 5.2 mg and the specific output was estimated as 144 ± 70 mg/km2/y.The measured methylmercury concentration in this study accounted for only 6 to 13% of the total dissolved organic bound mercury in the water sampl

ISSN:0730-7268    

DOI:10.1002/etc.5620090703

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe concentration of mercury in precipitation and in streams of a central Ontario lake were measured over a one year period. The concentrations in streams were generally very low (<5 ng/L), but during warm periods with low discharge, concentrations often exceeded 20 ng/L in a headwater stream draining a wetland. The concentration in precipitation varied from about 2 to nearly 30 ng/L and exhibited no seasonal pattern. By combining the concentration data with discharge and precipitation depth the inputs of mercury from runoff and direct deposition were estimated. Direct wet deposition accounted for over half of the supply of mercury to the lake. The watersheds retained most of the mercury deposited on them. The presence of wetlands appeared to decrease retention efficiency.

ISSN:0730-7268    

DOI:10.1002/etc.5620090704

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractRecent studies have demonstrated elevated levels of mercury in fish from remote, low alkalinity and low pH lakes. The mechanisms of this enhanced bioaccumulation are poorly understood, but the amount of methylmercury produced in a lake can play a major role. Decreased pH stimulates methylmercury production at the sediment‐water interface and possibly in the aerobic water column. Decreased pH also decreases loss of volatile mercury from lake water and increases mercury binding to particulates in water – factors that may increase methylation at low pH by enhancing the bioavailability of mercury for methylation. In anoxic subsurface sediments, decreased pH decreases the rate of mercury methylation, suggesting that methylmercury formation in the water column and at the sediment‐water interface may be most important in acidified lakes. Sulfate‐reducing bacteria are important mercury methylators in acidified lakes. Whether enhanced sulfate reduction stimulates methylmercury production in low pH lakes is presently unclear, although most of the available data do not support this hyp

ISSN:0730-7268    

DOI:10.1002/etc.5620090705

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractLittle Rock Lake is a low‐alkalinity (25 μeq/L, pH 6.1) seepage lake in north‐central Wisconsin. The two main basins of the lake were separated by a polyvinyl barrier in 1984, and acidification of the north basin with H2SO4began in spring 1985; the south basin is being maintained as a reference. The effects of acidification on dissolved concentrations of Al, Fe, Mn, Cd, Cu, Ni, Pb and Zn have been studied at three scales at Little Rock Lake: (A) laboratory‐scale experiments with well‐mixed sediments; (b) large (4‐ to 5‐m dia) in situ enclosures maintained at pH 4.5 to 6.0; and (c) the lake itself. In general, qualitative agreement is good between the three approaches, but some differences have been observed, especially for Al and Fe. The most significant trace metal response observed in acidifying the north basin from pH 6.1 to 5.1 has been a large increase in dissolved Mn, apparently as a result of hindered oxidation of Mn2+at lower pH. Dissolved Al and Fe also increased at pH 5.1 but not at 5.6. Water column levels of Cd, Cu, Pb and Zn have not increased at pH 5.1 in the lake, but results of lab and enclosure studies suggest that increased concentrations of Cd and Zn will occur when the lake is acidified to pH 4.6. Sediment cores and surface sediments from both basins of the lake have been collected and analyzed for Al, Fe, Mn, Cd, Cu, Hg, Ni, Pb and Zn. Similar concentrations of most metals were found in surface sediments from both basins of the lake. Near‐surface sediments were enriched in Hg and Pb relative to deeper sediment layers; the enrichment is presumed to be caused by increased atmospheric inputs during the past century, not diagenetic activity. No consistent differences in the Hg content of zooplankton, periphyton and benthic invertebrates were found at pH 5.6 and 5.1 in the acidified basin compared with the pH 6.1 r

ISSN:0730-7268    

DOI:10.1002/etc.5620090706

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractUnder certain conditions high concentrations of lead or cadmium in drinking water have occurred as a result of contamination from piping and distribution systems Contamination has led to acute and chronic toxicity in humans Metal concentration is increased when the acidity and corrosivity of water increase due to cultural acidification Adverse health effects have occurred in sen sitive subsections of human populations exposed to lead contaminated acidic water Neutralization of the acidity can reduce these problems Acidic water may also dissolve copper from piping systems Cirrhosis of the liver has been reported in children in India (Indian Childhood Cirrhosis – ICC), commonly with fatal outcome High liver copper levels in ICC cases have been related to copper exposure from cooking utensils Some rare cases reported from Germany and Italy have been partly attributed to high concentrations of copper in drinking water and partly to a special sensitivity to copper toxicity Elevated aluminum concentrations may occur in acidified natural waters and as a result of the aluminum chemicals used in drinking water purification Use of water con taming high aluminum levels for dialysis may give rise to dialysis dementia and disorders of bone mineral metabolism A possible relationship between aluminum in drinking water and Alzheimer's disease requires further investigati

ISSN:0730-7268    

DOI:10.1002/etc.5620090707

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractCadmium concentrations (Cd‐h) ofHolopedium gibberum(Crustacea, Cladocera) collected from 26 Canadian Shield lakes with positive alkalinity ranged from 0.9 to 31 μg/g. Levels were positively correlated with aqueous Cd concentrations (Cd‐aq) and negatively correlated with clutch size. Animals collected from acidified lakes did not have elevated Cd‐h concentrations despite elevated Cd‐aq levels. In three intensive study lakes, the presence of eggs lowered Cd‐h concentrations and Cd‐h levels frequently increased with increases in body size. In two of these lakes, manyH. gibberumoccupied waters rich in particulate iron just above the anoxic interface. Cd‐h levels fell when animals were experimentally confined to this layer, presumably because much of the Cd‐aq was adsorbed by the particulate iron and was unavailable for uptake. We suggest that the behavior of animals, specifically their movement to light‐scattering layers just above the anoxic interface, influences the accumulation of Cd byH. gibberumin Can

ISSN:0730-7268    

DOI:10.1002/etc.5620090708

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractWe studied the partitioning of mercury (Hg) among air, water, sediments and fish at Little Rock Lake, a clear water seepage lake in north‐central Wisconsin. The lake was divided with a sea curtain into two basins, one acidified with sulfuric acid to pH 5.6 for two years and the other an untreated reference site (mean pH 6.1), to document the effects of acidification. Trace‐metal‐free protocols were used to measure Hg at the picomolar level in air and water. Total gaseous Hg in air samples averaged 2.0 ng/m3. Total Hg in unfiltered water samples collected in 1986 after the fall overturn averaged about 1 ng/L in the acidified and reference basins. Mercury in surficial sediments was strongly correlated with volatile matter content and ranged from 10 to about 170 ng/g (dry weight) in both basins. Total Hg concentrations in whole, calendar age‐1 yellow perch (Perca flavescens), sampled after one year of residence in the lake, averaged 114 ng/g (fresh weight) in the reference basin and 135 ng/g in the acidified basin – a highly significant (p<0.01) difference. The mean whole‐body burden (quantity) of Hg in age‐1 perch did not differ between basins after the first year, but was significantly greater in the treatment basin than in the reference basin after the second year of acidification. Differences between the two basins in the bioaccumulation of Hg were attributed to internal (within‐lake) processes that influence the bioavailability of the metal. An initial Hg budget for the treatment basin of Little Rock Lake showed that atmospheric deposition and sedimentary remobilization of Hg are potentially important processes influencing its biogeochemical cycling and

ISSN:0730-7268    

DOI:10.1002/etc.5620090709

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY

摘要:

AbstractFish were sampled from 35 drainage and seepage lakes in the upper Michigan peninsula and Wisconsin in conjunction with Phase II of the U.S. Environmental Protection Agency's Eastern Lake Survey to explore the relationship between physicochemical characteristics of lakes and mercury concentrations in fish tissue. The lakes were selected using a stratified random design weighted for low pH to assess acidification effects on mercury bioaccumulation. Muscle tissue from yellow perch (Perca flavescens), northern pike (Esox lucius), white sucker (Catostomus commersoni) and largemouth bass (Micropterus salmoides) was analyzed for total and methylmercury. Differences in mercury concentrations were found between species, and methylmercury accounted for 99% of total mercury. Relationships were examined between tissue concentrations of mercury in yellow perch and lake physicochemical variables including pH, acid neutralizing capacity (ANC), calcium, conductivity, aluminum, total phosphorus, dissolved organic carbon, color, sulfate, lake area, lake depth, watershed area, Secchi depth and elevation. Mercury concentrations were negatively correlated with pH and ANC for both seepage and drainage lakes, but correlations with other water‐quality characteristics varied with lake type. Dissolved organic carbon had a negative correlation with fish mercury accumulation in seepage lakes, but not in drainage lakes. Mercury concentrations had a positive correlation with age, weight and length in yellow perc

ISSN:0730-7268    

DOI:10.1002/etc.5620090710

出版商:Wiley Periodicals, Inc.    

年代:1990

数据来源: WILEY