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1.
The present study to find seasonal (September 2010–June 2011) heavy metal (Cd, Pb, Cr, Co, Ni, Zn, Cu, Fe, As) contamination and the origins thereof in surface sediments of Gökçekaya Dam Lake, as constructed on Sakarya River, the third-longest river in Turkey and the largest river of the Northwestern Anatolia. Upon analyses for the purpose thereof, heavy metal contamination in annual average concentrations in the lake sediment varied, respectively, as Fe > Zn > Cr > Ni > Cu > Pb > Co > As > Cd. Statistical assessments performed in order to see whether the average values of the heavy metal contamination as measured at stations placed in the lake changed by seasonal periods. There found statistically significant differences especially in Cd, Zn, and Pb between seasonal periods. In accordance with the Sediment Quality Index, Gökçekaya Dam Lake sediment was classified as “highly polluted” in terms of the amount of anthropogenic contaminants of As, Cr, Cu, Ni, Pb, and Zn. Enrichment factor and geoaccumulation index values (I geo) were calculated in order to geochemically interpret the source of contamination due to heavy metal concentration in the lake sediment and the level of pollution. The As, Co, Cr, Cu, Ni Pb, and Zn values demonstrated that the sediment was rich for anthropogenic contaminants. The lake was found especially rich for arsenic (14.97–34.70 mg/kg) and lead (68.75–98.65 mg/kg) in accordance with annual average values. In general the lake was geochemically characterized as “moderately contaminated” in terms of As, Co, Cr, Cu, Ni, Pb, and Zn content.  相似文献   

2.
In order to assess the pollution levels of selected heavy metals, 45 bottom sediment samples were collected from Al-Kharrar lagoon in central western Saudi Arabia. The concentrations of the heavy metals were recorded using inductively coupled plasma-mass spectrometer (ICP-MS). The results showed that the concentrations of Pb and Cd exceeded the environmental background values. However, the heavy metal contents were less than the threshold effect level (TEL) limit. The concentrations of heavy metals in lagoon bottom sediments varied spatially, but their variations showed similar trends. Elevated levels of metals were observed in the northern and southern parts of the lagoon. Evaluation of contamination levels by the sediment quality guidelines (SQG) of the US-EPA revealed that sediments were non-polluted-moderately to heavily polluted with Pb; non-polluted to moderately polluted with Cu; and non-polluted with Mn, Zn, Cd, and Cr. The geoaccumulation index showed that lagoon sediments were unpolluted with Cd, Mn, Fe, Hg, Mo, and Se; unpolluted to moderately polluted with Zn and Co; and moderately polluted with Pb, Cr, Cu, and As. The high enrichment factor values for Pb, As, Cu, Cr, Co, and Zn (>2) indicate their anthropogenic sources, whereas the remaining elements were of natural origins consistent with their low enrichment levels. The values of CF indicate that the bottom sediments of Al-Kharrar lagoon are moderately contaminated with Mn and Pb.  相似文献   

3.
Eighteen sediment samples and six water-column samples were collected in a small (6 km2), coastal embayment (Port Jefferson Harbor, New York) to define a high-resolution spatial distribution of metals and to elucidate sources of contaminants to the harbor. Sediment metal (Ag, Cu, Fe, Ni, Pb, V, and Zn) concentrations varied widely, reflecting differences in sediment grain size, with higher metal concentrations located in the fine-grained inner harbor sediments. Calculated enrichment factors for these sediments show that Ag, Pb, Cu, and Zn are elevated relative to both crustal abundances and their respective abundances in sediments in central Long Island Sound. Metal concentrations were 1.2 to 10 fold greater in water from the inner harbor compared to water from Long Island Sound collected outside the mouth of the harbor. Spatial variations in trace metals in surface waters within the bay parallel the spatial variations of trace metals in sediments within the harbor. Elevated water-column metal concentrations appear to be partially derived from a combination of diagenetic remobilization from contaminated sediments (e.g., Ag) and anthropogenic sources (e.g., Cu and Zn) within the southern portions of the harbor. Although the National Status and Trends Program had reported previously that sediment metal concentrations in Port Jefferson Harbor were low, the results of this study show sediment metals have high spatial variability and are enriched in the inner harbor sediments at levels comparable to more urbanized western north shore Long Island harbors.  相似文献   

4.
Factors controlling the distribution of mining-derived Cu, Pb and Zn in the waters and bottom sediments of a large Andean lake (Lago Junin, Peru) have been assessed based on sample collections in May/June 1997 (dry season) and February/March 1998 (wet season). Relatively low levels of trace metals detected in surface waters of the lake during the dry season contrasted greatly with the high values observed during the wet period. Dry season concentrations of total Zn, Cu and Pb in the central lake basin averaged 41, 4.4 and 0.24 µg/L, respectively. In contrast, the respective wet season concentrations of total Zn, Cu and Pb in areas of the main basin ranged up to 387, 52 and 40 µg/L. The seasonal variability in metal concentrations largely reflects an increase in the concentration of particulate metal phases during the wet season. Such observations can be attributed to changes in sediment loadings associated with mining-derived river inputs and changes in lake circulation resulting from hydroelectric dam operations. Surface sediments are characterized by lake-wide enrichments of Zn, Cu and Pb, with maximum concentrations reaching as high as 5, 0.25 and 0.7 wt%, respectively. Estimated rates of authigenic metal accumulation are not sufficient to account for the elevated metal concentrations in the main basin of the lake, indicating that metal distributions are governed by the accumulation of metal-rich particulates. Variations in the spatial distributions of Zn, Cu and Pb are suggested to be a function of varying host phases and textural sorting.  相似文献   

5.
The concentration of trace metals like Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were studied in beach and estuarine sediments of the Velanganni Coast, South East coast of India to understand metal pollution due to urbanization/industrialization. This area was affected by the urbanization activity like untreated effluent discharge, transportation and incineration of solid waste, etc. In this context, quality of the sediments was evaluated based on the enrichment factor, geo-accumulation index (Igeo), pollution load index, and sediment quality guidelines. Furthermore, correlation matrix and principal compound analyses have been performed with SPSS 7.5 statistical software. The result illustrated that the metal enrichment is in the following order: Cd > Cr > Ni > Zn > Pb > Mn > Cu. The level of Igeo suggests that Cd has moderately polluted the sediment class. Similarly, principal component analysis showed that Cd and Pb accounted for the anthropogenic pollution, but Pb inferred as its tracers level. The results strongly indicate anthropogenic sources for moderate input of Cd contamination in to Velanganni coastal sediments.  相似文献   

6.
The purpose of this study was to determine if metal concentrations are enriched in two size sediment fractions of streams that receive landfill effluent and, if so, whether there is a greater extent of metal enrichment in one of the fractions. Sediment samples were collected from three streams adjacent to a sanitary landfill. Sediments representing control for the study were also collected from a stream not influenced by the landfill. All samples were sieved and the <0.0625-mm and <0.25-mm to >0.149-mm size fractions from each sample were used in this study. The concentrations of acid-extractable Cu, Zn, Pb, and Cr for all samples were determined by atomic absorption techniques. Mean concentrations, coefficient of variation values, at test, and the variation of metal concentrations along the stream were used to analyze the data. Results indicated that Cu, Zn, Pb, and Cr concentrations were enriched in both size sediment fractions from the stream whose channel originated at the base of the landfill. Copper, Zn, and Pb concentrations were enriched in the <0.0625-mm size sediments of the stream whose channel did not intersect the landfill. Copper, Zn, Pb, and Cr concentrations appear enriched in both size sediment fractions of the third stream, which formed from the confluence of the other two streams. The extent of metal enrichment was greater in the <0.0625-mm size sediments. A decreasing trend of metal concentrations in a downstream direction was not present in the enriched sediments. This was true for each metal in both size sediment fractions.  相似文献   

7.
Zn, Cu, Cr and Pb concentrations of the sediment collected from three tidal flat sites of Yangtze estuary were investigated in October 2003. Results showed that the average concentrations of heavy metals in the sediments were two to three times to the environment background values of Yangtze estuary tidal flat sediment. The heavy metal concentrations in the sediments near the Bailonggang (BLG) and Laogang (LG) sewage outfalls were obviously higher than those of Chaoyang (CY) tidal flat where there are no sewage outfalls near the coast. And the concentrations of heavy metals in the surface sediments of LG tidal flat decreased with the increasing of the distance to the sewage outfalls. The heavy metal concentration profile in the sediment core changed with the depth, and generally reached maximum values at the depth of plant roots. The assessment results showed that the sediments of LG, BLG and CY tidal flat had been polluted by heavy metals in different level. The pollution degree of heavy metals in the sediments was as follows: Zn > Cu > Pb > Cr. The potential ecological risks of the four heavy metals in three tidal flat sites sediment were all at a middle level, and Cu and Pb made the main contributions. The adverse ecological effects caused by the four heavy metals did not occur frequently.  相似文献   

8.
 The concentrations of various metals (Cr, Cu, Co, Fe, Mn, Ni, Pb, Zn, and Cd) were determined in recently deposited surface sediments of the Gomati River in the Lucknow urban area. Markedly elevated concentrations (milligrams per kilogram) of some of the metals, Cd (0.26–3.62), Cu (33–147), Ni (45–86), Pb (25–77), and Zn (90–389) were observed. Profiles of these metals across the Lucknow urban stretch show a progressive downstream increase due to additions from 4 major drainage networks discharging the urban effluents into the river. The degree of metal contamination is compared with the local background and global standards. The geoaccumulation index order for the river sediments is Cd>Zn>Cu>Cr>Pb. Significant correlations were observed between Cr and Zn, Cr and Cu, Cu and Zn and total sediment carbon with Cr and Zn. This study reveals that the urbanization process is associated with higher concentrations of heavy metals such as Cd, Cu, Cr, Pb, and Zn in the Gomati River sediments. To keep the river clean for the future, it is strongly recommended that urban effluents should not be overlooked before their discharge into the river. Received: 16 February 1996 · Accepted: 29 February 1996  相似文献   

9.
Transport and sediment–water partitioning of trace metals (Cr, Co, Fe, Pb, Cu, Ni, Zn, Cd) in acid mine drainage were studied in two creeks in the Kwangyang Au–Ag mine area, southern part of Korea. Chemical analysis of stream waters and the weak acid (0.1 N HCl) extraction, strong acid (HF–HNO3–HClO4) extraction, and sequential extraction of stream sediments were performed. Heavy metal pollution of sediments was higher in Chonam-ri creek than in Sagok-ri creek, because there is a larger source of base metal sulfides in the ores and waste dump upstream of Chonam-ri creek. The sediment–water distribution coefficients (K d) for metals in both creeks were dependent on the water pH and decreased in the order Pb ≈ Al > Cu > Mn > Zn > Co > Ni ≈ Cd. K d values for Al, Cu and Zn were very sensitive to changes in pH. The results of sequential extraction indicated that among non-residual fractions, Fe–Mn oxides are most important for retaining trace metals in the sediments. Therefore, the precipitation of Fe(–Mn) oxides due to pH increase in downstream sites plays an important role in regulating the concentrations of dissolved trace metals in both creeks. For Al, Co, Cu, Mn, Pb and Zn, the metal concentrations determined by 0.1 N HCl extraction (Korean Standard Method for Soil Pollution) were almost identical to the cumulative concentrations determined for the first three weakly-bound fractions (exchangeable + bound to carbonates + bound to Fe–Mn oxides) in the sequential extraction procedure. This suggests that 0.1 N HCl extraction can be effectively used to assess the environmentally available and/or bioavailable forms of trace metals in natural stream sediments.  相似文献   

10.
This investigation revealed the presence of traffic-derived metals within road, stream and estuarine sediments collected from a coastal catchment, northern Australia. Studied road sediments displayed variable total metal concentrations (median Cd, Cu, Pb, Pd, Pt, Ni and Zn values: 0.19, 42.6, 67.5, 0.064, 0.104, 36.7 and 698 mg/kg, respectively). The distinctly elevated Zn values are due to abundant tyre rubber shreds (as verified by SEM-EDS and correlation analysis). By comparison to the road sediments, background stream sediments taken upstream from roads have relatively low median Pb, Pd, Pt and Zn concentrations (7.3 mg/kg Pb, 0.01 mg/kg Pd, 0.012 mg/kg Pt, 62 mg/kg Zn). Stream and estuarine sediment samples collected below roads have median values of 21.8 mg/kg Pb, 0.014 mg/kg Pd, 0.021 mg/kg Pt and 71 mg/kg Zn, and exhibit 207Pb/206Pb and 208Pb/206Pb ratios that appear on a mixing line between the isotopically distinct background stream sediments and the road sediments. Thus, mobilisation of dusts and sediments from road surfaces has resulted in relatively elevated Pb, Pd, Pt and Zn concentrations and non-radiogenic Pb isotope ratios in local coastal stream and estuarine sediments. The investigation demonstrates that traffic-derived metals enter coastal stream and estuary sediments at the fringe of the Great Barrier Reef lagoon.  相似文献   

11.
A 24-cm long sediment core from an oxic fjord basin in Ranafjord, Northern Norway, was sliced in 2 cm sections and analysed for As, Co, Cu, Ni, Hg, Pb, Zn, Mn, Fe, ignition loss and Pb-210. Partitioning of metals between silicate, non-silicate and non-detrital phases was assessed by leaching experiments, in an attempt to understand the mechanisms of surface metal enrichment in sediments. Relative to metal concentrations in sediments deposited in the 19th century, metals in near surface sediments were enriched in the following order: Pb > Mn > Hg > Zn > Cu > As > Fe. Cobalt and Ni showed no enrichment. The non-detrital fraction of Cu, Pb, Mn and Zn was significantly higher in the upper 10 cm than at greater depth in the core. This corresponds to sediments deposited since 1900, when mining activities started in the area. The enrichment of Cu, Pb and Zn is assumed to be mainly a result of mining, while Mn is apparently enriched in the surface due to migration of dissolved Mn and precipitation in the oxic surface layer. Elevated concentrations of As and Fe in the upper 4 cm are presumably due to discharges from a coke plant and an iron works respectively. The excess Hg present in the near surface sediments is tightly bound, either in coal particles or ore dust introduced by local industry, or via long distance transport of atmospheric particles. Calculations of metal flux to the sediments indicate an anthropogenic flux of Zn equal to its natural flux, while the flux of Pb shows a threefold increase above natural input.  相似文献   

12.
A sequential extraction method was employed to extract the metals Al, Ag, Cd, Co, Cr, Cu, Pb, Fe, Li, Mn, Ni, and Zn from a 10-m sediment core taken from the Tilbury Basin on the Thames Estuary. Characteristics of the observed metal partitioning distributions were attributed primarily to the composition of the estuarine waters at the time of deposition. For some metals, a decrease in the bulk sediment metal concentrations from a depth of ?6.59 m ODN to the surface was also observed in one of the solid phases. This was the case for Cr, Cu, and Pb extracted from the organic phase and for Zn extracted from the carbonate phase. This decrease in sediment concentrations is thought to reflect reported improvements to water quality in this region of the Thames Estuary in the early 1960s, following updating of major sewage treatment works (STW) approximately 20 km upstream. These findings give an indication of the influence of estuarine inputs from STW on metal partitioning distributions. The order of mobility for the metals of environmental concern was Cd>Ag>Cr>Ni, Zn>Co, Cu, Pb. for Cd and Ag there was a tendency to partition towards the exchangeable phase, both at the surface and at depth, which indicates the potential for long-term leaching of these metals from the sediments.  相似文献   

13.
The abandoned Kilembe copper mine in western Uganda is a source of contaminants, mobilised from mine tailings into R. Rukoki flowing through a belt of wetlands into Lake George. Water and sediments were investigated on the lakeshore and the lakebed. Metal associations in the sediments reflect the Kilembe sulphide mineralisation. Enrichment of metals was compared between lakebed sediments, both for wet and dry seasons. Total C in a lakebed core shows a general increment, while Cu and Co decrease with depth. The contaminants are predominant (> 65%) in the ≤ 63 μm sediment size range with elevated Cu and Zn (> 28%), while Ni, Pb and Co are low (< 18%) in all the fractions. Sequential extraction of Fe for lakeshore sediment samples reveals low Fe mobility. Relatively higher mobility and biological availability is seen for Co, Cu and S. Heavy metal contents in lake waters are not an immediate risk to the aquatic environment.  相似文献   

14.
The Pliocene aquifer receives inflow of Miocene and Pleistocene aquifer waters in Wadi El Natrun depression. The aquifer also receives inflow from the agricultural activity and septic tanks. Nine sediment samples were collected from the Pliocene aquifer in Wadi E1 Natrun. Heavy metal (Cu, Sr, Zn, Mn, Fe, Al, Ba, Cr, Ni, V, Cd, Co, Mo, and Pb) concentrations of Pliocene aquifer sediments were investigated in bulk, sand, and mud fractions. The determination of extractable trace metals (Cu, Zn, Fe, Mn, and Pb) in Pliocene aquifer sediments using sequential extraction procedure (four steps) has been performed in order to study environmental pathways (e.g., mobility of metals, bounding states). These employ a series of successively stronger chemical leaching reagents which nominally target the different compositional fractions. By analyzing the liquid leachates and the residual solid components, it is possible to determine not only the type and concentration of metals retained in each phase but also their potential ecological significance. Cu, Sr, Zn, Mn, Fe, and Al concentrations are higher in finer sediments than in coarser sediments, while Ba, Cr, Ni, V, Cd, Co, Mo, and Pb are enriched in the coarser fraction. The differences in relative concentrations are attributed to intense anthropogenic inputs from different sources. Heavy metal concentrations are higher than global average concentrations in sandstone, USEPA guidelines, and other local and international aquifer sediments. The order of trace elements in the bulk Pliocene aquifer sediments, from high to low concentrations, is Fe?>?Al?>?Mn?>?Cr?>?Zn?>?Cu?>?Ni?>?V?>?Sr?>?Ba?>?Pb?>?Mo?>?Cd?>?Co. The Pliocene aquifer sediments are highly contaminated for most toxic metals, except Pb and Co which have moderate contamination. The active soluble (F0) and exchangeable (F1) phases are represented by high concentrations of Cu, Zn, Fe, and Mn and relatively higher concentrations of Pb and Cd. This may be due to the increase of silt and clay fractions (mud) in sediments, which act as an adsorbent, retaining metals through ion exchange and other processes. The order of mobility of heavy metals in this phase is found to be Pb?>?Cd?>?Zn?>?Cu?>?Fe?>?Mn. The values of the active phase of most heavy metals are relatively high, indicating that Pliocene sediments are potentially a major sink for heavy metals characterized by high mobility and bioavailability. Fe–Mn oxyhydroxide phase is the most important fraction among labile fractions and represents 22% for Cd, 20% for Fe, 11% for Zn, 8% for Cu, 5% for Pb, and 3% for Mn. The organic matter-bound fraction contains 80% of Mn, 72% of Cu, 68% of Zn, 60% of Fe, 35% of Pb, and 30% of Cd (as mean). Summarizing the sequential extraction, a very good immobilization of the heavy metals by the organic matter-bound fraction is followed by the carbonate-exchangeable-bound fraction. The mobility of the Cd metal in the active and Fe–Mn oxyhydroxide phases is the highest, while the Mn metal had the lowest mobility.  相似文献   

15.
Heavy metal pollution in the surficial sediments derived from the estuary in Daliao River and Yingkou Bay is investigated to assess environmental quality, pollution level, bioavailability and toxicity. The ranges of Pb, Co, Zn and Cu concentrations in the surficial sediments are: 16.57–39.18, 3.61–16.02, 16.53–39.18, 2.77–43.80 mg/kg. Results of the geoaccumulation index (I geo) show that the pollution levels of four metals are in the “unpolluted” class except for Pb in 15 sampling sites. The pollution level of the study area assessed by pollution load index (PLI) shows that except for the moderately polluted region of sites 1, 2, 3, 8, 12 and 13, other sites belong to unpolluted state. The sequence of pollution extent of different heavy metals is: Pb > Zn > Co > Cu. At all sampling sites, the grades of potential ecological risk of Co, Cu, Pb and Zn are “light”. The order of potential ecological risk is: Pb > Co > Cu > Zn. Sequential extraction of the metals indicates that the states of Pb, Cu, Co and Zn in the sediment are relatively stable at most sites of the estuary in Daliao River and Yingkou Bay, which means that there is a low source of pollution arriving in this area. While only at several sites, Co, Pb and Zn are labile, which are considered as anthropogenically originated.  相似文献   

16.
Three marine sediment cores from Osaka Bay were analyzed for 210Pb geochronology, heavy metal concentrations (Zn, Cu, and Pb) and stable lead isotope ratios (206Pb/207Pb) in order to reconstruct high-resolution heavy metal pollution history from 1900–2006. Anthropogenic metal accumulation in sediments peaked in 1970 in agreement with the high economic growth period in Japan. The comparison of temporal patterns of 206Pb/207Pb ratio with other areas of Japan suggested that the heavy metals, imported from several different countries during the periods of economic growth (1955 to 1973), are the main pollution source for the country. For the period 1970–2006, the sediment data reflect the result of stricter environmental regulations applied after the late 1960s. However, heavy metal concentrations in the surface sediments are still elevated to levels several times higher than the levels at the bottoms of the cores. Additionally, the lead isotope ratio does not show significant change after the 1980s. Secondary heavy metal pollution through the mixing of deeper polluted sediment appears to be the likely reason for the deterioration of present time submarine sediment environments. In conclusion, this study has demonstrated that it is difficult to recover over a period of several years the benthic quality of a bay, once it is heavily polluted.  相似文献   

17.
 The Yamuna River sediments, collected from Delhi and Agra urban centres, were analysed for concentration and distribution of nine heavy metals by means of atomic adsorption spectrometry. Total metal contents varied in the following ranges (in mg/kg): Cr (157–817), Mn (515–1015), Fe (28,700–45,300), Co(11.7–28.4), Ni (40–538), Cu (40–1204), Zn (107–1974), Pb (22–856) and Cd (0.50–114.8). The degree of metal enrichment was compared with the average shale concentration and shows exceptionally high values for Cr, Ni, Cu, Zn, Pb and Cd in both urban centres. In the total heavy metal concentration, anthropogenic input contains 70% Cr, 74% Cu, 59% Zn, 46% Pb, 90% Cd in Delhi and 61% Cr, 23% Ni, 71% Cu, 72% Zn, 63% Pb, 94% Cd in Agra. A significant correlation was observed between increasing Cr, Ni, Zn, and Cu concentrations with increasing total sediment carbon and total sediment sulfur content. Based on the Müller's geoaccumulation index, the quality of the river sediments can be regarded as being moderately polluted to very highly polluted with Cr, Ni, Cu, Zn, Pb and Cd in the Delhi and Agra urban centres. The present sediment analysis, therefore, plays an important role in environmental measures for the Yamuna River and the planning of these city centres. Received: 21 June 1999 · Accepted: 1 October 1999  相似文献   

18.
This study reports a multi-parameter geochemical investigation in water and sediments of a shallow hyper-eutrophic urban freshwater coastal lake, Zeekoevlei, in South Africa. Zeekoevlei receives a greater fraction of dissolved major and trace elements from natural sources (e.g., chemical weathering and sea salt). Fertilizers, agricultural wastes, raw sewage effluents and road runoff in contrast, constitute the predominant anthropogenic sources, which supply As, Cd, Cu, Pb and Zn in this lake. The overall low dissolved metal load results from negligible industrial pollution, high pH and elevated metal uptake by phytoplankton. However, the surface sediments are highly polluted with Pb, Cd and Zn. Wind-induced sediment resuspension results in increased particulate and dissolved element concentrations in bottom waters. Low C/N ratio (10) indicates primarily an algal source for the sedimentary organic matter. Variation in sedimentary organic C content with depth indicates a change in primary productivity in response to historical events (e.g., seepage from wastewater treatment plant, dredging and urbanization). Primary productivity controls the enrichment of most of the metals in sediments, and elevated productivity with higher accumulation of planktonic debris (and siltation) results in increased element concentration in surface and deeper sediments. Aluminium, Fe and/or Mn oxy-hydroxides, clay minerals and calcareous sediments also play an important role in adsorbing metals in Zeekoevlei sediments.  相似文献   

19.
 Bottom-water data and trace metal concentration of Cu, Cr, Ni, Pb, Co, Zn, and organic matter in surficial sediment samples from 13 sampling stations of Lake Chapala in Mexico were studied. The lake is turbid with a great amount of flocculated sediments as a result of wind mixing, sediment re-suspension, and Lerma River discharges. Al distribution pattern in sediments was used as an indicator of the Lerma River discharges into Lake Chapala. The highest values of Cu (33.27 ppm), Cr (81.94 ppm), Pb (99.8 ppm), and Zn (149.7 ppm) were detected in sediments near the lake outlet. The bioavailable metal fraction is low for all metals except Pb, which shows 65–93% of the total metal concentration in bioavailable form. The minimum energy zone in the lake was related to organic matter concentration and was located in the SE part of the lake. An analysis of the studied parameters shows two zones: eastern zone (fluvio-deltaic) and central-western zone (lacustrine). Received: 9 September 1998 · Accepted: 16 November 1998  相似文献   

20.
The technique of diffusive gradients in thin films (DGT) was applied to obtain high-resolution vertical profiles of trace metals in sediment porewater of a eutrophic lake, Lake Chaohu. All sampling sediments were under anaerobic conditions with Eh values below 0, the redox potential profile in M4 was relatively stable, and higher Eh values in M4 than that in M1 were observed due to hydrodynamic effects. Fe, Mn and As exhibited closely corresponding profiles due to the co-release of Fe and Mn oxides and the reduction of As. Higher Fe and Mn concentrations and lower As concentrations were observed in M1 of the western half-lake than those in M4 of the eastern half-lake due to different sources and metal contamination levels in the two regions. Cu and Zn showed increasing concentrations similar to Mn and Fe at 1–2 cm depth of sediments, while DGT measured Co, Ni, Cd and Pb concentrations decreased down to 3–4 cm in the profiles. Co, Ni, Cu, Zn, Cd and Pb showed insignificant regional concentration variances in the western and eastern half-lakes. According to the R(C DGT/C centrifugation) values, the rank order of metal labilities decrease as follows: Fe (>1) > Cu, Pb, Zn (>0.9) > Co, Ni, Cd (>0.3) > Mn, As (>0.1).  相似文献   

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