Heavy Metal Contamination and Ecological Risk Assessment of Swine Manure Irrigated Vegetable Soils in Jiangxi Province,China

Heavy metal are often added to animal fodder and accumulate in the soils with swine manure. In this study, heavy metal (Cu, Pb, Cd, Zn, As and Cr) concentrations were determined in agricultural soils irrigated with swine manure in Jiangxi Province, China. Results showed that the average concentrations of Cu, Zn, As and Cr (32.8, 93.7, 21.3 and 75.8 mg/kg, respectively) were higher than the background values, while Pb and Cd (15.2 and 0.090 mg/kg, respectively) were lower than the background values. Contamination factors \(\left( {C_{f}^{i}} \right)\) indicated that they were generally moderate for Cu, Zn, As and Cr and generally low for Pb and Cd. The contamination degree (C _d ) was calculated to be 7.5–10.0 indicating a moderate degree of contamination. The geoaccumulation index (I_geo) indicated that the soils were unpolluted with Zn, Cd and Pb, while unpolluted to moderately pollute with Cr, Cu and As. The single ecological risk factor \(\left( {E_{r}^{i}} \right)\) revealed that the six heavy metals all belonged to low ecological risk. The ecological risk indices suggested that all the sampling sites were at low risk level.     

Decennary Variations of Dissolved Heavy Metals in Seawater of Bohai Bay,North China

Characteristics of the spatial and temporal distributions of selected dissolved heavy metals (Cu, Zn, Pb, Hg and Cd) in Bohai Bay, north China was investigated. Water samples from 22 sites were collected and analyzed for the selected metals with atomic absorption spectrometry from the year of 1996 to 2005. Relatively high concentrations of Cu, Zn, Pb and Hg were detected, with maximum concentrations in the 10-year period of 16.30, 422.00, 40.40, 0.23 μg/L respectively. The concentrations of Cd in all samples were quite low, with maximum level of 0.89 μg/L. The spatial distribution of dissolved Cu, Zn and Pb was analogous, where their average concentrations generally descended from the coastline to the central areas of the bay. Differently, for Hg and Cd, relatively high concentrations occurred not only in inshore but also in offshore areas. Measured data of heavy metals were compared with sea water quality standard of China (SWQSC). Cd concentrations in all samples were below SWQSC Grade-I. The percentages of Cu, Zn, Pb, and Hg at Grade-III levels in Bohai Bay were 2.67%, 30.00%, 30.43% and 0.36%, respectively, suggesting the severe contamination of Zn and Pb in this area. Terrestrial inputs via different rivers and sewages may be the important source for the heavy metals contamination.     

Heavy Metal Toxicity and Differential Effects on the Hyperglycemic Stress Response in the Shrimp Palaemon elegans

Agricultural and industrial activities cause heavy metal pollution of the aquatic environment. The sensitivity of crustaceans to heavy metals is well documented. However, the hormonal and metabolic target of physiological functions affected by sublethal toxicity and stress responses have been scarcely investigated. Exposure of Palaemon elegans to increasing concentrations of heavy metals dissolved in artificial sea water resulted in an order of toxicity tested by LC₅₀ for 96 h in intact and eyestalkless animals in which Hg is the most toxic, followed by Cd, Cu, Zn, and Pb. Eyestalkless animals were found to be more sensitive than intact individuals. Heavy metals affect the blood glucose levels, yet manipulative stress does not. The intermediate sublethal concentrations of Hg, Cd, and Pb produced significant hyperglycemic responses within 3 h, while the highest concentrations elicited no hyperglycemia in 24 h. In contrast, animals exposed to Cu and Zn showed hyperglycemia even at high concentrations. This difference in response between Cu or Zn and the nonessential heavy metals Cd, Hg, or Pb can probably be explained by the physiological roles of the former in crustaceans and by tolerance adaptations. Involvement of the crustacean hyperglycemic hormone (cHH) was tested by routine bioassay on eyestalkless individuals; each group was injected with a two-eyestalk-equivalent extract from control animals or from shrimp exposed to high concentrations of Cd, Hg, Pb, or low concentrations of Cu or Zn. All showed a hyperglycemic response within 2 h. In contrast, extracts of eyestalk removed from animals that had developed a full hyperglycemic reaction after exposure to low concentrations of Hg, Cd, Pb, or high concentrations of Cu and Zn were depleted of cHH as shown by the attenuation of the response after injection of the extracts into eyestalkless animals. This generalized and predictable sublethal response can be used as a quantitative physiological biomarker for water quality monitoring assessment. Received: 22 September 1999/Accepted: 9 March 2000     

Background Concentrations of Heavy Metals in Benthos from Transboundary Rivers of the Transbaikalia Region, Russia

The concentrations (mg/kg dry weight) of Cu, Zn, As, Cd, Hg, and Pb were measured in benthic macroalgae and invertebrates collected in the upper transboundary tributaries of the Onon River, Transbaikalia, Russia. The background concentration ranges in Cladophora fracta, Ulothrix zonata and Zygnemataceae were: 6.4–9.1 for Cu, 27.2–73.1 for Zn, 0.4–0.9 for Cd, 6.7–35.3 for As, 0.01–0.02 for Hg, and 1.9–4.3 for Pb. In Brachycentrus americanus and Lymnaea media the concentration ranges were: 9.0–25.5 for Cu, 21.4–96.0 for Zn, 0.1–0.3 for Cd, 1.7–5.6 for As, 0.004–0.02 for Hg, and 0.4–2.2 for Pb. The concentrations of Cu, Zn, Pb, and Hg were consistent with data for uncontaminated areas. Under contamination conditions the concentrations in C. fracta were: 938 for Zn, 513 for Pb, and 9.5 for Cd; in Lymnaea media were: 46.8 for Cu, 176 for Zn, 52.3 for Pb, and 3.0 for Cd. All the organisms showed a common response to contamination, and consequently can be used as biomonitors of contamination by heavy metals.     

Determination of selected heavy metal concentrations and distribution in a southwestern stream using macrophytes

Since the reduction of the arsenic standard from 50 to 10 μg L⁻¹ by the US Environmental Protection Agency in 2006 many small town and rural water municipalities were left with the task of preventing or mitigating arsenic contamination of drinking water supplies. In this study macrophytes and sediments were used to determine the concentration and distribution of heavy metals (As, Cd, Cu, Pb, and Zn) within the primary source of drinking water (Gallinas River watershed) to the residents of Las Vegas, New Mexico. Sampling was done in the spring and fall at four sites, two above the city and two below, and samples were analyzed using ICP-MS. Results showed significantly higher (p<.05) metal concentrations in plant roots than shoots for most metals. Spearman’s correlation showed positive correlations (r>.3) between plant and sediment concentrations of Cd, Pb, Zn, As, and a negative correlation for Cu. The site above waste water treatment plant (AWWTP) had the highest plant tissue concentrations of Cd, Pb, Zn, and As. All of these concentrations attained critical toxicity levels exceeding sediment quality guidelines. High concentration factor values and levels of metals detected in macrophyte tissues indicate that heavy metals within sediments in the Gallinas River occur in bioavailable forms. Correlations between plant and sediment metal concentrations indicate that metal concentrations in macrophyte tissues are a good reflection of metal concentrations within the sediment in the Gallinas River.     

Historical Characteristics of Contamination and Risk of Heavy Metals in Weishan Lake,China

Combined with the dating analysis of ²¹⁰Pb and ¹³⁷Cs, the historical concentration and risk of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in the core sediment of Weishan Lake were determined. Pollution concentrations, enrichment factor, geo-accumulation index, and ecological risk index of these metals and C/N ratio indicate that the natural inputs prevailed till early 1900s. From late 1970s onwards, the risk posed by these metals was significantly increased. Cu and Hg might cause adverse biological effects. The increase of soil erosion and wastewater discharge in the watershed promoted input and accumulation of these metals in the lake. The coal and petroleum industry in the catchment led the more accumulation of Hg, Cd and Cu in the lake.     

Heavy Metals in Livers of Waterbirds from Spain

Wetlands tend to accumulate heavy metals from local sources, such as Pb shot used for waterfowl hunting, and from regional sources, such as atmospheric deposition and riverine or marine inputs. We determined concentrations of six heavy metals (Cr, Mn, Cu, Zn, Cd, and Pb) in livers of waterbirds shot by hunters in five Spanish wetlands to study the different factors that can contribute to the accumulation of these metals (sex, age, diet, grit, and Pb shot ingestion). Differences among wetlands were observed only for Cr, Cu, and Cd. Differences among species were observed for all the metals, and Cu was notably higher in pochards (Aythya and Netta genus) than in other waterfowl. Cu, Zn, and Cd concentrations increased with age, and only Pb showed differences related to sex, with males having higher concentrations than females. Most metals other than Pb were correlated with each other. Lead was dependent on Pb shot ingestion. Grit ingestion positively correlated with concentrations of Cr and to a lesser extent with Mn, Zn, and Cd. Ingestion of grit or shot may obscure relationships between metals and diet. Herbivorous species, which had more grit in the gizzard, had higher Cr, Zn, and Cd concentrations. Granivorous birds, which have the highest rates of Pb shot ingestion, had the highest concentrations of Pb. Grit and Pb shot ingestion are both important sources of heavy metals for waterbirds. Lead was the single metal studied whose concentrations exceeded toxicity thresholds. Received: 5 March 2002/Accepted: 12 June 2002     

Monitoring of Trace Metal Contamination in the Souss Estuary (South Morocco) Using the Clams <Emphasis Type="Italic">Cerastoderma edule</Emphasis> and <Emphasis Type="Italic">Scrobicularia plana</Emphasis>

Concentrations of seven metals (Cd, Cu, Cr, Pb, Ni, Zn, Hg) were monitored monthly during 2 years in two bivalves, Cerastoderma edule and Scrobicularia plana collected from the Souss estuary (South Morocco) before and after the commissioning of a sewage treatment plant in November 2002. According to trace metals, changes in concentrations were observed mainly in S. plana, characterised by a decrease of Cu, Hg and Pb when Cd was clearly increasing. Conversely, no clear changes were observed in C. edule during the same periods. This study suggests the use of S. plana in the monitoring of trace metal contamination of such coastal marine environments.     

Heavy Metal Concentrations in Food Chain of Lake Velenjsko jezero, Slovenia: An Artificial Lake from Mining

The concentration of metals (Pb, Cd, Zn, Hg) in different ecosystem components (lake water, sediment, plankton, macrophytes, and fish tissues) has been determined in Velenjsko jezero, an artificial lake resulting from mining activity. The risk to humans from consuming fish has been evaluated from the heavy metal load of fish muscle tissue. Heavy metals are transferred through the food chain at different levels, and Hg is found to be the element of the highest ecotoxicological concern. Although both sediment and plankton contain relatively low concentrations of Hg, this element accumulates in high levels in fish, especially in the benthivorous species Abramis brama danubii and predator species Perca fluviatilis. Moreover, Hg appears to be very mobile in the fish organism. Whereas the other metals remained mostly in liver (Cd) or gills (Zn, Pb), levels of Hg in fish muscle and liver were the same and markedly higher than in gills. However, in muscle, the average concentrations of each metal were below their maximum limits, determined either by Slovenian legislation or by the Food and Agriculture Organization.     

Assessment of Heavy Metal Contamination in Roadside Surface Soil and Vegetation from the West Bank

Concentrations of heavy metals (Pb, Cd, Cu, Zn, Fe, Mn, Ni, and Cr) were investigated in roadside surface soil and the common perennial herb inula (Inula viscosa L., Compositae). Samples were collected at different distances (0–200 m) perpendicular to a main road that connects two main cities in the West Bank. Average concentrations of metals in soil samples were: Pb, 87.4; Cd, 0.27; Cu, 60.4; Zn, 82.2; Fe, 15,700; Mn, 224; Ni, 18.9; and Cr, 42.4 g · g^–1. In plant leaves, concentrations were: Pb, 7.25; Cd, 0.10; Cu, 10.6; Zn, 47.6; Fe, 730; Mn, 140; Ni, 4.87; and Cr, 7.03 g · g^–1. Roadside contamination was obvious by the significant negative correlations between concentrations of metals in soil and plant samples and distance from road edge. Only cadmium concentrations in soil and plant samples were not associated with roadside pollution. Roadside contamination in plants and soil did not extend much beyond a 20 m distance from road. I. viscosa reflected roadside contamination better than soil and their metal concentrations showed much less fluctuations than those in soil samples. Washing plant leaves decreased Pb and Fe concentrations significantly, indicating a significant aerial deposition of both. I. viscosa can be considered as a good biomonitor for roadside metal pollution.     

Heavy Metal Concentrations in Marine Fishes Collected from Fish Culture Sites in Hong Kong

The levels of six heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) in different tissues of three species of cultured marine fishes (Epinephelus areolatus, Lutjanus russelli, and Sparus sarba) collected from three fish culture sites in Hong Kong were evaluated. Metal pollution problems in the fish culture sites were serious, as reflected by the high metal concentrations recorded in sea water, sediments, and the biomonitor Perna viridis. In general, tissues of all three species contained high concentrations of Zn and Cu, but much lower concentrations of Ni, Pb, Cd, and Cr. Similar pattern of heavy metal concentrations was observed in sea water, sediment, and P. viridis. Metal concentrations in various tissues varied greatly among species and among fish culture sites. Different tissues showed different capacity for accumulating heavy metals. Gonad of all three species contained high concentrations of Zn. On the other hand, liver seemed to be the primary organ for Cu accumulation. Overall, metal concentrations in the tissues of culture marine fishes were much lower than those in P. viridis. Despite high metal levels in sea water and sediments, concentrations of Cd, Cr, and Pb in edible tissues, including muscle and skin, did not exceed permissible levels recommended by the Hong Kong Government for human consumption. Received: 3 December 1999/Accepted: 13 June 2000     

Heavy Metal Pollution Characteristics in the Modern Sedimentary Environment of Northern Jiaozhou Bay,China

The particle size distribution characteristics of sediments and the concentrations of heavy metals in Jiaozhou Bay were investigated in this study. The average concentrations of Cu, Pb, Zn, Cr, Cd, Hg and As were 36.88, 29.60, 82.08, 77.48, 0.083, 0.048 and 11.00 mg/kg, respectively. The heavy metal concentrations were highest in the eastern sediments, followed by those at the top of the bay, and the lowest concentrations were observed in the central region. Overall, a decreasing trend from the center of the bay to the periphery was observed. Additionally, the distribution of heavy metals in sediments was not completely controlled by sediment particle size. The degree of heavy metal contamination was evaluated using the geoaccumulation index and Hakanson’s method. The results revealed that the level of heavy metal pollution in the sediments was relatively low and that the main pollution elements were Cu and Hg. In addition, the sediments are associated with various levels of potential ecological risk due to the high pollution levels of Hg and Cd.     

Toxic element contamination and the occurrence of mercury-resistant bacteria in Hg-Contaminated soil,sediments, and sludges

River sediment, sludge, and soil samples were collected and analyzed for Hg, MeHg, Cd, Cr, Cu, Ni, Pb, and Zn. Volatile solids, chloride, sulphate, and sulphide were also assessed. Heavy metal contamination was present in all the samples, particularly soil and sediment. The 'k values for Cu were less than those for Hg and lower for soil than for river sediment. Complexation may be a major factor in Hg methylation as high 'k values reflected low MeHg levels. High chloride concentration was associated with low ratios of methyl to total Hg. Using DNA probe technology, the occurrence of DNA sequences typical of transposons Tn₂1 and Tn₅₀₁ were determined for the samples. Observable (phenotypic) Hg resistance was greatest at sites of high Hg and chloride concentrations although genetic variation was greatest in soil and sediment samples with lower Hg concentrations. Isolation of Tn501-like elements increased when Hg was added to the medium. Mercury resistance systems which are not homologous at high stringency to themer operon appear to be common in soil, activated sludge, and river sediments.     

Mercury and Other Mining-Related Contaminants in Ospreys Along the Upper Clark Fork River,Montana, USA

We investigated links between mining-related contaminants in river sediment and their occurrence in nestling ospreys (Pandion haliaetus) in the Clark Fork River Basin, Montana, USA. Blood and feather samples from 111 osprey chicks were collected during 4 years from nests along river sections with greatly different sediment concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), and mercury (Hg). No significant differences between river sections were found among Zn (3,150 ± 160 μg L⁻¹) and Cd (<5 μg L⁻¹) concentrations in blood. Cu, Pb, and As concentrations in blood were significantly increased in chicks from the most contaminated river sections (mean values of 298, 8.9, and 100 μg L⁻¹, respectively). Cu, Zn, and Pb concentrations increased significantly during a year of above-average river runoff combined with high suspended sediment loads in rivers. Total Hg concentrations in blood and feathers were highly correlated and depended on the geographic locations of the nests. The lowest blood concentrations of Hg were observed in the most upstream river section (mean 151 μg L⁻¹) where total sediment concentrations were increased (0.80 mg kg⁻¹). River sections with intermediate blood concentrations (mean 206 and 303 μg L⁻¹) were associated with low to intermediate sediment concentrations (0.058 and 0.46 mg kg⁻¹). The highest concentrations of Hg in ospreys (mean 548 μg L⁻¹) were observed downstream from a contaminated tributary (1–4 mg kg⁻¹ in sediment). In river sections with lower Hg concentrations in sediment, there was a negative correlation between blood Hg concentration and chick mass, presumably due to high deposition rates into growing feathers. This relationship was absent in sections of high Hg exposure. Osprey blood and feathers are suitable for monitoring Hg in aquatic ecosystems; however, responses of As, Cd, Cu, Pb, and Zn are more subtle.     

Elemental Status in Sediment and American Oyster Collected from Savannah Marsh/Estuarine Ecosystem: A Preliminary Assessment

Sediment and American oyster (Crassostrea virginica) collected from nine selected marsh/estuarine ecosystems in Savannah, Georgia were analyzed for elements such as Al, As, B, Cd, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Si, and Zn. Sediments were extracted by ammonium acetate (NH₄OAc), Mehlich-3 (M-3), and water procedures, whereas an acid digestion procedure was adopted for oyster tissue. Concentrations of elements were higher in M-3 extractions followed by NH₄OAc and water extraction procedures. Calcium and Mg was greater in sediments by any of the extractions, whereas other elements differed depending upon the extraction procedures. There were no significant spatial variations (p < 0.05) of any of elements analyzed except Mn, in NH₄OAc/water extraction procedure and Fe and Al by water extraction procedure. Contamination of Al, B, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Si, and Zn in oyster tissue ranged from 399 to 1460, 231 to 254, <1.5 to 2.9, <1.5 to 8.0, 67 to 121, 232 to 1357, 17 to 54, <0.5 to 0.64, <1.5 to 2.5, <1.5 to 4.0, 241 to 381, and 978 to 2428 μg/g dry weight (dw), respectively. Greatly elevated concentrations of elements such as P, Ca, Mg, K, and S were noticed in oyster tissue. The concentration range of Hg and As in sediment was 1.2–1.9 and 11–55 μg/g dw, respectively. The concentration range of Hg and As in oyster tissue was 130–908 and 200–912 ng/g dw, respectively. With the exception of As and Hg, other elements are several orders of magnitude greater in oyster tissue. There is no significant (p < 0.05) contamination variation in target analyses between the nine selected sites. Concentrations of heavy metals in sediment and oyster were either comparable or lower than those of other countries. Greater biota-sediment accumulation factor was noticed for P and Zn. Concentrations of Hg and P in oyster tissue were higher than the threshold limit for human consumption. Overall, the baseline data can be used for regular ecological monitoring, considering the domestic and industrial growth around this important marsh/estuarine ecosystem.     

Element differences and evaluation of the dietary intake from farmed oysters and mussels collected at different sites along the Croatian coast of the Adriatic Sea

Concentrations of the macroelements Ca, Mg, K and Na, microelements Cr, Cu, Fe, Mn and Zn and toxic metals As, Cd, Hg and Pb were determined in oysters and mussels collected at farming sites in the northern, central and south Adriatic Sea. Mean concentrations in oysters were (mg kg⁻¹): As 4.51, Ca 1551, Cd 1.44, Cu 53.6, Cr 0.23, Fe 45.9, Hg 0.047, K 2476, Mg 895, Mn 2.80, Na 7148, Pb 0.52, Zn 675. Mean values in mussels were (mg kg⁻¹): As 4.71, Ca 601, Cd 0.37, Cu 1.91, Cr 0.29, Fe 49.6, Hg 0.026, K 2246, Mg 1043, Mn 2.49, Na 7992, Pb 0.58, Zn 28.8. Significant differences in the concentrations of toxic metals and elements were found in oysters and mussels among farming sites. Obtained Cd, Hg and Pb concentration in oysters and mussels were lower than the limit levels set by the European Community. However, Cd concentration exceeded the limit level of 1 mg kg⁻¹ in oysters from all locations except Lim Bay. The estimated daily intakes (EDIs) indicate that oysters are a good source of Ca, Cu and Zn. The higher Cu and Zn concentrations than the toxicity reference values suggest a risk for consumers if larger quantities of oysters are consumed frequently.     

Metal Concentrations of Common Freshwater and Marine Fish from the Pearl River Delta,South China

Sediments and fish, including tilapia (Oreochromis mossambicus), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idellus), and mandarin fish (Siniperca chuatsi) were collected from different fish ponds in the Pearl River Delta (Tanzhou, Sanjiao, Guangzhou, Shipai, Changan, and Mai Po) for the analysis of metalloids and heavy metals [arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb)]. The pollution of As in pond sediments was great; however, As in the edible parts of pond fish were within the international permissible safety levels for human consumption. Axial muscles from 10 species each of freshwater and marine fish purchased from markets in Hong Kong were also analyzed for As, Cd, Cr, Cu, Hg, Ni, Pb and Zn. Freshwater fish contained 0.24 to 2.13 mg/kg As, 0.10 to 0.17 mg/kg Cd, 0.09 to 0.36 mg/kg Cr, 0.06 to 0.35 mg/kg Cu, 0.07 to 0.34 mg/kg Hg, 0.04 to 0.36 mg/kg Ni, 0.11 to 0.52 mg/kg Pb, and 2.67 to 19.1 mg/kg Zn (wet weight). Marine fish had higher Hg and lower Pb concentrations than freshwater fish. A few fish species had average concentrations greater than the international standards for Cd and Pb established by the European Union and the China National Standard Management Department. Total Hg concentrations in 10 of 20 market fish species were generally greater than those of the World Health Organization’s recommended limit of 0.2 mg/kg for at-risk groups, such as children and pregnant women. Daily intake through fish consumption of these metals were compared with the Provisional Tolerable Weekly Intake proposed by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives. There appears to be potential threat to local people from Hg contamination because of the high marine fish consumption rate (142 g/d/person).     

Concentrations of Metals in Water,Sediment, Biofilm,Benthic Macroinvertebrates,and Fish in the Boulder River Watershed,Montana, and the Role of Colloids in Metal Uptake

To characterize the partitioning of metals in a stream ecosystem, concentrations of trace metals including As, Cd, Cu, Pb, and Zn were measured in water, colloids, sediment, biofilm (also referred to as aufwuchs), macroinvertebrates, and fish collected from the Boulder River watershed, Montana. Median concentrations of Cd, Cu, and Zn in water throughout the watershed exceeded the U.S. EPA acute and chronic criteria for protection of aquatic life. Concentrations of As, Cd, Cu, Pb, and Zn in sediment were sufficient in the tributaries to cause invertebrate toxicity. The concentrations of As, Cu, Cd, Pb, and Zn in invertebrates from lower Cataract Creek (63, 339, 59, 34, and 2,410 μg/g dry wt, respectively) were greater than the concentrations in invertebrates from the Clark Fork River watershed, Montana (19, 174, 2.3, 15, and 648 μg/g, respectively), that were associated with reduced survival, growth, and health of cutthroat trout fed diets composed of those invertebrates. Colloids and biofilm seem to play a critical role in the pathway of metals into the food chain and concentrations of As, Cu, Pb, and Zn in these two components are significantly correlated. We suggest that transfer of metals associated with Fe colloids to biological components of biofilm is an important pathway where metals associated with abiotic components are first available to biotic components. The significant correlations suggest that Cd, Cu, and Zn may move independently to biota (biofilm, invertebrates, or fish tissues) from water and sediment. The possibility exists that Cd, Cu, and Zn concentrations increase in fish tissues as a result of direct contact with water and sediment and indirect exposure through the food chain. However, uptake through the food chain to fish may be more important for As. Although As concentrations in colloids and biofilm were significantly correlated with As water concentrations, As concentrations in fish tissues were not correlated with water. The pathway for Pb into biological components seems to begin with sediment because concentrations of Pb in water were not significantly correlated with any other component and because concentrations of Pb in the water were often below detection limits.     

Levels, Spatial Distribution and Possible Sources of Heavy Metals Contamination of Suburban Soils in Tianjin, China

Representative soil samples (n = 86) of suburban areas in Tianjin (Xiqing, Dongli, Jinnan, Beichen) were evaluated for heavy metals. The results showed that the average concentration of Cr, Cu, Zn, As, Cd, Pb and Hg in soil of Tianjin suburban was 101.0, 67.0, 100.6, 9.5, 0.49, 52.5 and 0.97 mg/kg, respectively. Pollution of Cr and Zn were minimal compared to the other elements while concentrations of Cd and Hg were higher than their natural background values. Spatial variations of Cd, Hg, Pb and Cu in soil were illustrated; Pollution status and comparison in the four districts were also investigated. Higher concentrations of Hg and Cd were found in soils of Beichen than others indicating that Beichen was suffering from metal contamination. Principal Component Analysis in combination with local specific environment suggested that heavy metal contamination had different origination. Wastewater and sludge irrigation, air deposition might be the most important sources. These results, especially the spatial distribution of pollutants, would be helpful to develop proper management strategies and decrease source pollution by various remediation practices in Tianjin, China.     

Metal distribution in the earthworm,Pheretima hilgendorfi,and their variations with growth

The concentrations and distribution of metals (Fe, Mn, Zn, Cu, Pb, Ni, Co, As, Hg, and Cd) in an earthworm,Pheretima hilgendorfi, and their variations with growth were investigated. Higher concentrations of the metals were found in the pre-clitellar regions of the earthworm compared with the post-clitellar ones; Cd, Cu, and Hg were relatively high in the gut wall. The body concentration of Pb and Hg decreased with increased body length (age) and weight, while the opposite was found for Cd and As. The accumulation of Fe, Mn, Zn, Cu, Ni, and Co in the earthworm depends primarily on the metabolic turnover, whereas the accumulation of Pb, Hg, Cd and As, is dependent upon the age or exposure time. Small earthworms showed faster uptake and excretion rates of Pb and Hg than the large ones, and the biological half-lives of Pb and Hg were relatively short compared with those of Cd and As. The large earthworms exhibited a decrease of Hg in the bodies, probably due to excretion of Hgvia spawning. Based upon these results, the sizes and parts of the earthworm suitable for purposes of research are discussed.