Heavy metals in tropical Lake Kariba,Zimbabwe

Metal mining is carried out in the drainage basin of Lake Kariba, Zimbabwe. In an attempt to assess the distribution of heavy metals in the lake ecosystem, the concentrations of chromium (Cr), cadmium (Cd), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), zinc (Zn), and selenium (Se) were analysed in the following ecosystem components at different locations in the lake; water, sediment, aquatic macrophytes, mussels, and carnivorous and herbivorous fish. Concentrations were generally in the same range as in other temperate and tropical aquatic ecosystems, except for Pb and Cd, which were higher in marcrophytes and fish from the lake. Apart from Cd, there were no signs of biomagnification and the highest levels of metals were found in the macrophytes and sediments. While metal contamination in fish is probably a combination of uptake from the food and an equilibrium with the surrounding water, the levels in macrophytes appear to be determined mainly by uptake from the sediment through the roots.     

Occurrence and distribution of chemical pollutants in Lake Mariut,Egypt

Occurrence and distribution of organochlorine pesticides in the water of Lake Mariut, a brackish coastal Egyptian lake suffering from pollution, and their accumulation in the common fish Tilapia were studied. The major pesticides detected in the lake water were lindane, p,p′-DDE, o,p′-DDT, and p,p′-DDT. These compounds, except o,p′-DDT, were detected in the fish samples in exceedingly higher concentrations compared with those found in the lake water.     

Relationships of Heavy Metals in Natural Lake Waters with Physico-chemical Characteristics of Waters and Different Chemical Fractions of Metals in Sediments

The relationships between heavy metal concentrations and physico-chemical properties of natural lake waters and also with chemical fractions of these metals in lake sediments were investigated in seven natural lakes of Kumaun region of Uttarakhand Province of India during 2003–2004 and 2004–2005. The concentrations of Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb in waters of different lakes ranged from 0.29–2.39, 10.3–38.3, 431–1407, 1.0–6.6, 5.3–12.1, 12.6–166.3, 0.7–2.7 and 3.9–27.1 μg l^?1 and in sediments 14.3–21.5, 90.1–197.5, 5,265–6,428, 17.7–45.9, 13.4–32.0, 40.0–149.2, 11.1–14.6 and 88.9–167.4 μg g^?1, respectively. The concentrations of all metals except Fe in waters were found well below the notified toxic limits. The concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were positively correlated with pH, electrical conductivity, biological oxygen demand, chemical oxygen demand and alkalinity of waters, but negatively correlated with dissolved oxygen. The concentrations of Cr, Ni, Zn, Cd and Pb in waters were positively correlated with water soluble + exchangeable fraction of these metals in lake sediments. The concentrations of Zn, Cd and Pb in waters were positively correlated with carbonate bound fraction of these metals in lake sediments. Except for Ni, Zn and Cd, the concentrations of rest of the heavy metals in waters were positively correlated with organically bound fraction of these metals in lake sediments. The concentrations of Cr, Mn, Ni, Cu and Zn in waters were positively correlated with reducible fraction of these metals in lake sediments. Except for Cd, the concentrations of rest of the metals in waters were positively correlated with residual fraction and total content of these heavy metals in lake sediments.     

Trace element accumulation in the tissues of fish from lakes with different pH values

Two species of fish, omnivorous Catostomus commersoni (white suckers) and carnivorous Perca flavescens (yellow perch) were collected from three natural lakes with different pH ranges (circumneutral, pH 6.5 to 6.8; variable, pH 5.8 to 6.7; and acidic, pH 4.9 to 5.4). The lakes are located in the North Branch of the Big Moose River drainage system in the New York State Adirondack Park Preserve. Concentrations of potentially toxic elements (Al, Cd, Cu, Ph, and Se) were measured by electrothermal atomic absorption spectrophotometry in water, sediment and fish (bone, gill, kidney, liver and muscle) from each lake. The results showed that concentrations of Pb and Cd were significantly higher (P < 0.05) in some of the tissues of the fish collected from the acidic lake. Also, the yellow perch from the acidic take had significantly higher (P<0.05) Se concentrations in their muscle and livers than fish from the other lakes. The concentrations of Al were elevated in the gill tissues of both fish species from the acidic lake relative to fish from the other lakes. Possible mechanisms contributing to these differences in tissue concentration are discussed.     

Metal concentration in the gill,gastrointestinal tract,and carcass of white suckers (Catostomus commersoni) in relation to lake acidity

Adult white suckers were collected from four lakes in Maine that ranged in pH from 7.0 to 5.4. The gastrointestinal tract and remainder of the carcass of fishes of similar age and size from each lake, and gills from additional fishes of similar size, were analyzed for Al, Cd, Pb, and Zn. Carcasses were also analyzed for Hg. Concentrations of Al, Cd, and Pb were highest in the gastrointestinal tract and lowest in the carcass; Zn concentration was highest in the gill. For carcass, all metals except Al differed significantly among lakes, for gill tissue Cd and Pb differed, and for gastrointestinal tract, only Cd differed among lakes. Where differences were significant, patterns among lakes were similar in each tissue analyzed. Concentrations of Cd, Hg, and Pb were negatively correlated with lake water pH, acid neutralizing capacity (ANC), Ca, and lake:watershed area, and positively correlated with lake water SO₄, indicating that concentrations were higher in fish from more acidic lakes. Zinc concentrations in gills were unrelated to lake acidity, and carcass concentrations were higher in the less acidic lakes, which is the opposite of the pattern for the other metals studied. Zinc in gastrointestinal tract did not differ among lakes. Although the lakes we studied were located in undisturbed watersheds and did not receive any point source discharges, fish metal concentrations were comparable to or higher than those reported from waters receiving industrial discharges.     

Metals in stocked Lake Trout (Salvelinus namaycush) in lakes near Sudbury,Canada

Muscle tissue from stocked lake trout (Salvelinus namaycush) from lakes near the smelters at Sudbury, Canada was analyzed for Al, Cu, Fe, Hg, Mn, Ni, and Zn. Metals in tissue were not abnormally high compared with fish from lakes farther away from the smelters. Tissue concentrations of Al, Fe, Mn, and Zn declined significantly after stocking. Because metal concentrations were lower in hatchery water than the study lakes, this decline in tissue metal suggests that diet plays a prominent role in the uptake of these metals in lake trout. Only Hg showed evidence of accumulation to levels that might be harmful for human consumption, and then only in a few older, larger trout. In contrast, tissue Mn and Zn were inversely correlated with trout weight. Fluctuations, independent of age, body weight or time of year, were observed in tissue concentrations of Al, Cu, and Zn. Annual cycles, independent of pH and alkalinity were observed in tissue concentrations of Fe, Hg, Mn, and Ni. Bioaccumulation of metal proved to be an unfounded concern for the rehabilitation of fish populations in lakes near Sudbury.     

Responses of perch,Perca fluviatilis L., from an acidic and a neutral lake to acidic later

Responses to low pH of perch, Perca fluviatilis, from a naturally acid and a neutral lake were compared by 24 hr exposures to pH 4.6, 4.1 and 3.8 and by 72 hr exposures to pH 4.5. Plasma osmolality and plasma concentrations of Na and chloride decreased in fish from both lakes during acid exposures. Significant differences between the populations were observed at pH 4.1 and 4.5. Hematocrits of the fish from the acid lake increased rapidly and at higher pH compared with those of fish from the neutral lake. This was interpreted as an adaptation to their normal acidic environment, connected with the maintenance of red cell oxygen affinity. The perch from the acid lake maintained their muscle water balance at lower pH better than did the fish from the neutral lake.     

Fates of metal radiotracers added to a whole lake: Accumulation in fathead minnow (Pimephales promelas) and lake trout (Salvelinus namaycush)

Six gamma-emitting isotopes, Se-75, Hg-203, Cs-134, Fe-59, Zn-65 and Co-60, were introduced simultaneously in a single epilimnetic addition to an oligotrophic lake on the Precambrian Shield of northwestern Ontario, Canada. Accumulation of each isotope was monitored in fathead minnow (Pimephales promelas) for 274 days. Isotope accumulation in blood, gill, gut, liver, kidney, spleen, gonad, brain, muscle and gut contents of lake trout (Salvelinus namaycush) was monitored for 352 days. Fish accumulated only traces of Fe-59. Isotopes which occured in water primarily in the charcoal-extracted fraction (Se-75 and Zn-65) were most readily accumulated by fish. Fathead minnow accumulated higher concentrations of all isotopes than lake trout. In lake trout, the highest concentrations of isotopes were found in the following tissues: Se-75, liver; Hg-203 and Co-60, kidney; Cs-134, muscle; Zn-65, gut. Food seemed to be the primary source of all isotopes to fish. Ratios of isotope concentrations in fish to those in water were higher for both fathead minnow and lake trout than ratios reported from laboratory studies using aqueous exposures. Concentration ratios for Cs-134 in both fathead minnow and lake trout from oligotrophic Lake 224 were over an order of magnitude greater than published data for fish from eutrophic lakes.     

In Situ partitioning and biomagnification of mercury in industrially polluted Husainsagar Lake,Hyderabad, India

The distribution of Hg in water, sediment, plankton and fish along with the in situ biomagnification of the metal in Husainsagar Lake, India were measured. The concentration of Hg in the water was 10 μg L^?1 and exceeded the water quality criteria standards. Sediments of the lake at different sites had Hg concentrations several thousand fold more than that of the overlying water column and showed relationship with the water content of the wet sediment. Sediments in the lake acted as a `sink' for the metal. The concentrations of Hg increased from nanoplankton → phytoplankton -> zooplankton. Fish, an end organism in the food chain, had Hg concentrations higher than that of nanoplankton and lower than those of phytoplankton and zooplankton. This trend did not illustrate the expected pattern of food chain enrichment in the classical sense as noted for chlorinated hydrocarbons (DDT).     

Pathological and Hormonal Changes in Freshwater Fishes Due to Exposure to Heavy Metals Pollutants

The concentrations of major heavy metals in organs of two cyprinid fish and in water collected from three sections of the Kor River, Iran, were determined using the induction coupled plasma method. The concentrations of heavy metals in tissue of fish from the middle sampling zone were significantly higher (p?<?0.05) than those from the other two sampling zones, whereas no significant differences (p?>?0.05) were detected between the two sexes and species. Estradiol in females and progesterone and testosterone in males from the middle study site were significantly (p?<?0.05) lower than values from the other two sites. Pathological changes in blood cells, liver, and kidneys of fishes were significantly higher in highly polluted areas (middle sampling zone). So heavy metals exposure can effectively decreases estrogenic and androgenic secretion in fish. These results show that industrial activities have polluted the river and that heavy metals exposure can induce pathological changes in fish organs.     

Opening Pandora's Box: An Evaluation of Auto Salvage Yards as Sources of Toxicants in Watersheds and Their Effects on Fish Survivorship and Growth Rate

We determined the effects of auto salvage yards on fathead minnow larvae in Northcentral, Northeast, and Southwest Arkansas areas. Fathead minnows (N = 1800) were stocked into microcosms with varying percentages of ephemeral stream water (0, 6, 12.5, 25, 50, and 100%) from auto salvage yard areas and monitored for changes in weight and survivorship. Growth rates and survivorship were significantly reduced at higher concentrations. In addition, we evaluated auto salvage yards as potential sources of heavy metals and analyzed fish tissues for the presence of these metals. Although no concentrations of metals were significantly greater than zero in fish tissues, Mn, Cu, Pb, Zn, and Al water concentrations within ephemeral streams at all three salvage yard areas were greater than regulatory limits. Our results support the need for further analyses of salvage yards as sources of toxicants and their effects on fish.     

Metal Status of Soils and Plants Irrigated with Water from Lake İznik,Turkey

Lake ?znik, located in the southeast part of the Marmara region in Turkey, is considered the largest lake in the region. Soil pollution from irrigation with lake water has become an important concern for arable lands surrounding the lake. Therefore, a study was conducted to investigate trace element contamination of soils and plants irrigated with water from the lake, which has been polluted with industrial and municipal wastes. Eleven different crops grown in 30 different horticultural fields, consistently irrigated with lake water, were studied. To determine pollutant concentrations, soils, plants, and water were sampled and analyzed for both total and extractable iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), chromium (Cr), lead (Pb), and cadmium (Cd). Iron, Cu, and Ni in destructively sampled soils were found to be excessive in soils. The results were subjected to statistical analysis using simple correlations and t‐test. There were no statistically significant relationships among the total and extractable metals in soils and extractable plant metals. Because of lack of standard concentrations indicating excessive concentration of extractable elements, statuses of extractable elements in the soils were not evaluated. Cobalt, Pb, Cr, and Cu concentrations were greater than the normal range in leaves. The accumulation of metals differed greatly among the various plant species, but irrigation with lake water did not increase metals in soils. The appearance of metals in soils might be due to agricultural activities and parent material. Continuous monitoring and future studies of the area are recommended to ascertain long‐term impacts of pollution on plants.     

Heavy Metals in Polish Forest Stands of Quercus Robur and Q. Petraea

This study aimed to compare concentrations of Zn, Cd, Pb and Cu in wood of Quercus robur and Q. petraea and in the soil on 21 plots in different parts of Polish lowlands. Concentrations of those metals in growth rings taken with an increment borer were measured in 20-year periods. The curves of radial distribution of heavy metals in growth rings are highly variable, but usually a greater variation was observed in sapwood than in heartwood. This attests to transport of metals in the younger, functional xylem, and confirms earlier observations. Quercus petraea accumulated significantly more Zn but less Cd than Q. robur, while concentrations of other metals were similar in both species. No significant correlations between levels of different metals in oak wood were detected, except a strong correlation between Pb and Cd. Concentrations of heavy metals in oak wood were generally not correlated with their concentrations in the soil. Most of the forest stands can be regarded as free from pollution with heavy metals.     

In situ compartmentation and biomagnification of chromium and manganese in industrially polluted Husainsagar Lake,Hyderabad, India

The concentrations of Cr and Mn in water, sediment, nanoplankton, phytoplankton, zooplankton, and fish were determined during 1983–1984, to investigate biomagnification of these metals in Husainsagar Lake, India. The concentration of Cr in the water phase was above the permissible limits and Mn exhibited complex distribution pattern. The high concentrations of Cr and Mn in the surficial sediment was related to an increase in the intensity of in situ processes, mainly the enrichments of these metals in the organisms. The concentration of Cr was least in nanoplankton and remained the lowest in samples of phytoplankton, zooplankton and fish. The concentration of Mn decreased from nanoplankton to fish, except in phytoplankton which showed the highest concentration. This trend did not illustrate the expected pattern of food chain enrichment in the classic sense of the term as noted for Hg and DDT. Furthermore, the Mn, but not the Cr, concentrations decreased with the increase in body weight of the fish.     

Modeling of Solute Transport with Bioremediation Processes using Sawdust as a Matrix

Hg and As are widespread contaminants globally and particularly in Asia. We conducted a field study in Baiyangdian Lake, the largest lake in the North China Plain, to investigate bioaccumulation and trophic transfer of potentially toxic metals (total mercury and arsenic) in sites differing in proximity from the major point sources of nutrients and metals. Hg concentrations in fish and As concentrations in water are above critical threshold levels (US Environmental Protection Agency based) considered to pose some risk to humans and wildlife. Hg concentrations in biota are within the range of concentrations in lakes in the Northeast US despite the high levels of Hg emission and deposition in China whereas As concentrations are much higher. Dissolved concentrations of both Hg and As decrease with increasing chlorophyll concentrations suggesting that there is significant uptake of metal from water by algae. These results provide evidence for algal blooms controlling dissolved metal concentrations and potentially mitigating the trophic transfer of Hg to fish. This study also underscores the need for further investigation into this contaminated ecosystem and others like it in China that are an important source of fish and drinking water for consumption by local human populations.     

Changes in the fish community of a limed lake near sudbury,Ontario: Effects of chemical neutralization or reduced atmospheric deposition of acids?

Nelson Lake, a moderately acidic (pH 5.7), metal-contaminated (Cu 22 μg L^?1; Zn 18 ug L^?1) lake, 28 km from the smelters at Sudbury, had a degraded fish community in the early 1970's, with lake trout (Salvelinus namaycush) scarce, smallmouth bass (Micropterus dolomieui) extinct, and the littoral zone dominated by the acid-tolerant yellow perch (Perca flavescens). Liming of the lake in 1975–76 increased pH to 6.4, and decreased metal concentrations. Chemical conditions have remained relatively stable in the 10 yr following base addition. Initially, it appeared that neutralization produced dramatic changes in the resident fish community. Yellow perch abundance declined rapidly after neutralization, lake trout abundance increased to the extent that 3.26 kg ha^?1 were caught in the winter of 1980, and reintroduced smallmouth bass reproduced and established a large population. However, these changes in the fish community can not be directly attributed to liming, as water quality and the sport fisheries of an unlimed nearby lake also improved. Reduced emissions from Sudbury smelters were responsible for improvements in the untreated lake. Recovery of the lake trout population in Nelson Lake appears to have begun prior to liming. Of the lake trout sampled during the 1980 winter fishery, 65.8% were present prior to the chemical treatment. Predation by lake trout was the likely cause of the perch decline. Our results suggest that chemical conditions producing population level responses in fish have abrupt thresholds and that neutralization of lakes above these thresholds may not produce distinguishable effects.     

Low Success Rate in Re-Establishing European Perch in Some Highly Acidified Lakes in Southernmost Norway

In order to test whether major reductions in acid inputs had improved water quality sufficiently for fish populations to recover, we stocked wild European perch (Perca fluviatilis) in three highly acidified lakes that had previously supported this species, and in one limed lake. The fish, which were introduced from a local lake (donor lake), generally ranged from 12 to 16 cm in total length, and were stocked at densities of 117–177 fish ha^?1. The untreated lakes were highly acid, with minimum pH values and maximum inorganic aluminium concentrations (Al_i) during the spring of 4.6–4.7 and 118–151 µg L^?1 respectively. In the limed lake, the corresponding values for pH and Al_i ranged between 5.8 and 6.6 and 5 and 19 µg L^?1 respectively. Gill-netting in two subsequent years after the introduction yielded only a few recruits (0+) and one adult in one of the three acidified lakes in one year only. However, stocked perch reproduced successfully in both years in the limed lake. There was a significant linear relationship between the catches (CPUE) of juvenile perch (age 0+) in the different lakes in the autumn and the water quality in May (time of hatching), both in terms of Al_i (r ²=0.934, P<0.05) and pH (r ²=0.939, P<0.05). Our data suggest unsuccessful recruitment in waters of pH <5.1 and Al_i>60 µg L^?1.     

Phytoremediation Potential of Vetiver Grass (<Emphasis Type="Italic">Vetiveria zizanioides</Emphasis>) for Treatment of Metal-Contaminated Water

Phytoremediation using vetiver grass (Vetiveria zizanioides) has been regarded as an effective technique for removing contaminants in polluted water. This study was conducted to assess the removal efficiency of heavy metals (Cu, Fe, Mn, Pb, Zn) using vetiver grass (VG) at different root lengths and densities and to determine metals uptake rate by plant parts (root and shoot) between treatments (low and high concentration). Removal efficiency for heavy metals in water by VG is ranked in the order of Fe>Pb>Cu>Mn>Zn. Results showed that VG was effective in removing all the heavy metals, but removals greatly depend on root length, plant density and metal concentration. Longer root length and higher density showed greater removals of heavy metals due to increased surface area for metal absorption by plant roots. Results also demonstrated significant difference of heavy metals uptake in plant parts at different concentrations indicating that root has high tolerance towards elevated concentration of heavy metals. However, the effects were less significant in plant shoot suggesting that metals uptake were generally higher in root than in shoot. The findings have shown potential of VG in phytoremediation for heavy metals removal in water thus providing significant implication for treatment of metal-contaminated water.     

Evaluation of Heavy Metal Pollution in the Arabian Gulf Using the Clam Meretrix meretrix Linnaeus, 1758

The present study is an attempt to assess the heavy metal contamination in the marine environment of the Arabian Gulf of Saudi Arabia. The concentrations of heavy metals in water and the soft tissues of the bivalve species Meretrix meretrix Linnaeus, 1758, from different stations along the Arabian Gulf coastline, were determined during the summer season of 2008. Bioaccumulation of some heavy metals (Cd, Pb, Cu, and Zn) in fresh parts of the clam (M. meretrix) was measured by an atomic absorption spectrophotometer. The average concentrations of heavy metals in the clam tissues were 0.224?C0.908, 0.294?C2.496, 3.528?C8.196, and 12.864?C24.56 mg/kg wet weight for Cd, Pb, Cu, and Zn, respectively. In water, the mean concentration values of these metals were arranged in the following descending order: Pb > Cu > Zn > Cd. The heavy metal concentrations in tissues of M. meretrix were within the acceptable standards set by the US Environmental Protection Agency, the Commission Européenne, and the Food and Drug Administration of the USA. From the human public health point of view, these results seem to show no possibility of acute toxicities of Cd, Cu, Pb, and Zn if the edible clam is consumed. It is recommended that relevant authorities should carry out a continual assessment on the levels of these pollutants in the studied area.