Trace metal concentrations in tidal flat coastal sediments, Yamaguchi Prefecture, southwest Japan

Geochemical investigations of tidal flat coastal sediments at Ogori, Ozuki, and Kasado in Yamaguchi Bay of southwest Japan were conducted to determine their metal concentrations and to assess contamination levels, compared with sediment quality guidelines (SQG) and several pollutant indicators. Selected major oxides, trace elements, and total sulfur (TS) were determined by X-ray fluorescence. pH values of most samples were alkaline, indicating anoxic conditions. Average abundances of As, Pb, Zn, Cu, Ni, and Cr in Ozuki sediments were 11, 27, 109, 21, 19, and 52 mg/kg, respectively, compared to 9, 29, 80, 16, 18, and 42 mg/kg at Ogori and 12, 27, 151, 34, 30 and 80 mg/kg at Kasado, respectively. Average concentrations of As, Zn, and Cu in all samples and TiO(2), Fe(2)O(3), and P(2)O(5) at Kasado were greater than those of the upper continental crust. Contamination levels were assessed based on SQG, contamination factors (CF), pollution load index (PLI), enrichment factor (EF), and index of geoaccumulation (Igeo). According to the SQG of the US EPA, the sediments were heavily polluted with respect to As, whereas Zn, Cu, Ni, and Cr were classed as moderately polluted. The elevated CF values of As, Pb, and Zn identify moderate to considerable contamination, indicating that these metals are potentially toxic in the study area. Based on PLI and EF, the study sites are moderate to moderately severe polluted with As and Pb, moderately polluted with Zn, and weakly contaminated to noncontaminated with Cu, Ni, and Cr. The highest Igeo values for As, Pb, and Zn in the surface and core sediments reflected the tendency of metal contamination that seems to be related to their fine-grained nature, organic matter-rich sediments, and anthropogenic point sources. Trace metal contents were strongly correlated with Fe(2)O(3) and TiO(2), suggesting that Fe oxyhydroxides and detrital clastic load play a role in controlling abundances in the study area.     

Recent sedimentary environment of coastal lagoon in southwestern Japan: evidence from major and trace elements

A geochemical study of the bottom sediments of Lake Shinji and the River Ohashi in southwestern Japan was carried out to determine their elemental compositions and to evaluate the pollution status of lake sediments by employing enrichment factor (EF), pollution load index (PLI), and geoaccumulation index (I _geo). Present-day water quality was also assessed. Results showed that the water quality of Lake Shinji contrasts slightly between the upper and lower parts. The chemical composition of the sediments, as measured by X-ray fluorescence, included major and trace elements and total sulfur (TS). Average abundances of As, Pb, Zn, Cu, Ni, and Cr in the Shinji sediments were 10, 29, 143, 27, 19, and 54 ppm, respectively, compared to 6, 18, 57, 16, 10, and 37 ppm in the river sediments. Based on the EF, PLI, and I _geo, the lake sediments are moderately to strongly polluted with respect to As, moderately polluted with Pb, Zn, and Cr, and unpolluted with Cu and Ni. The high EF and I _geo for As, Pb, and Zn in the lake sediments indicate that metal concentration has occurred in Shinji. Increases in the abundances of these metals are likely related to the fine-grained nature of the sediments, reducing conditions of the bottom sediments, enrichment in organic matter, and possibly a minor contribution from non-point anthropogenic sources. Trace metal contents are strongly correlated with Fe₂O₃ and TS, suggesting that Fe oxides and sulfides play a role in controlling abundances in the investigated areas.     

Anthropogenic impacts on heavy metal concentrations in the coastal sediments of Dumai, Indonesia

Concentrations of Cd, Cu, Pb, Zn, Ni and Fe were determined in the surface sediments to investigate the distributions, concentrations and the pollution status of heavy metals in Dumai coastal waters. Sediment samples from 23 stations, representing 5 different site groups of eastern, central and western Dumai and southern and northern Rupat Island, were collected in May 2005. The results showed that heavy metal concentrations (in microg/g dry weight; Fe in %) were 0.88 (0.46-1.89); 6.08 (1.61-13.84); 32.34 (14.63-84.90); 53.89 (31.49-87.11); 11.48 (7.26-19.97) and 3.01 (2.10-3.92) for Cd, Cu, Pb, Zn, Ni and Fe, respectively. Generally, metal concentrations in the coastal sediments near Dumai city center (eastern and central Dumai) which have more anthropogenic activities were higher than those at other stations. Average concentration of Cd in the eastern Dumai was slightly higher than effective range low (ERL) but still below effective range medium (ERM) value established by Long et al. (Environmental Management 19(1):81-97, 1995; Environmental Toxicology Chemistry 17(4):714-727, 1997). All other metals were still below ERL and ERM. Calculated enrichment factor (EF), especially for Cd and Pb, and the Pollution load index (PLI) value in the eastern Dumai were also higher than other sites. Cd showed higher EF when compared to other metals. Geo-accumulation indices (I(geo)) in most of the stations (all site groups) were categorized as class 1 (unpolluted to moderately polluted environment) and only Cd in Cargo Port was in class 2 (moderately polluted). Heavy metal concentrations found in the present study were comparable to other regions of the world and based on the calculated indices it can be classified as unpolluted to moderately polluted coastal environment.     

Metal pollution assessment of sediment and water in the Shur River

Intensified industrialization and human activities have resulted in the release of various contaminants into the environment. Among them, heavy metals are often present as a result of mining, milling and industrial manufacturing. In the present investigation, bulk concentrations Pb, Cd, Zn, Cu, Fe, Ca and Al in Shur River (Iran) bed sediments and water around the Sarcheshmeh copper mine were measured from several sample locations. In addition, partitioning was assessed to determine the proportions of metals in different forms. The degree of sediment contamination was evaluated using an Enrichment Factor (EF) and geo-accumulation index (I (geo)) and a newly developed pollution index (I (POLL)). Elevated metals in sediment and water were found to be correlated with areas of the river that were proximal to direct and indirect mining activities. Cadmium and Zn showed the highest pollution index. Cluster analysis was performed in order to assess heavy metal interactions between water and sediment. Chemical partitioning studies revealed that organic metallic bonds were not significantly present in the sediment of the Shur River.     

Heavy metal assessment using geochemical and statistical tools in the surface sediments of Vembanad Lake, Southwest Coast of India

The geochemical distribution and enrichment of ten heavy metals in the surface sediments of Vembanad Lake, southwest coast of India was evaluated. Sediment samples from 47 stations in the Lake were collected during dry and wet seasons in 2008 and examined for heavy metal content (Al, Fe, Mn, Cr, Zn, Ni, Pb, Cu, Co, Cd), organic carbon, and sediment texture. Statistically significant spatial variation was observed among all sediment variables, but negligible significant seasonal variation was observed. Correlation analysis showed that the metal content of sediments was mainly regulated by organic carbon, Fe oxy-hydroxides, and grain size. Principal component analysis was used to reduce the 14 sediment variables into three factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Pollution intensity of the Vembanad Lake was measured using the enrichment factor and the pollution load index. Severe and moderately severe enrichment of Cd and Zn in the north estuary with minor enrichment of Pb and Cr were observed, which reflects the intensity of the anthropogenic inputs related to industrial discharge into this system. The results of pollution load index reveal that the sediment was heavily polluted in northern arm and moderately polluted in the extreme end and port region of the southern arm of the lake. A comparison with sediment quality guideline quotient was also made, indicating that there may be some ecotoxicological risk to benthic organisms in these sediments.     

贵州某流域城市河段沉积物及悬浮物重金属污染研究

通过在丰水期对贵州省某流域城市河段悬浮物和沉积物中的重金属含量进行测定,运用单因子指数法、生态风险评价法、因子分析法,初步探讨了该河段Cu、Zn、Pb、Hg、Cd、Cr、Ni及As等8种重金属元素的含量分布、污染特征、潜在生态风险及主要来源。检测结果显示,沉积物和悬浮物中Hg、Cd、Zn、Pb、As的平均含量较高,是贵州省土壤背景值的1.02～16.97倍。单因子指数评价结果表明：在沉积物中,Zn、Pb、As为轻度污染,Hg和Cd为重度污染;在悬浮物中,Cu、Pb、As为轻度污染,Zn为中度污染,Hg和Cd为重度污染。潜在生态风险指数评价结果显示,Hg和Cd的生态风险最大,为主要污染元素。研究区沉积物样品综合生态风险指数(RI)介于183.27～1 393.96,平均值为912.06,总体处于严重生态风险等级;悬浮物样品RI值介于341.53～612.38,平均值为436.85,总体处于重度生态风险等级。其中,沉积物样品重金属平均生态风险等级高于悬浮物样品,支流样品重金属生态风险等级总体上低于干流下游样品。根据因子分析法分析结果,初步推测沉积物及悬浮物Hg、Cd、Cr、Ni含量主要受工...     

Source identification and assessment of sediment contamination of trace metals in Kogarah Bay,NSW, Australia

The distribution of trace metals (spatial and temporal) and sedimentary fractions were investigated to identify the concentrations and sources of trace metals within Kogarah Bay, NSW, Australia. A total of 59 surface sediments and six subsurface samples from core of the sediment were collected. The contamination factor and pollution load index indices used to evaluate environmental effects of trace metals. The study area was found to be uncontaminated with Cr and Ni, moderately contaminated with As and considerably contaminated with Cu, Zn and Pb. The concentrations of Cr and Ni were below both effect range low and effect range median, while As, Cu, Zn and Pb were slightly above effect range low. The highest concentrations of these trace metals such as Cu, Zn and Pb were found in the north, northwest and southeast of the bay, close to discharge points, stormwater outlets and around boatyards and watercrafts. The spatial distributions of metals were strongly related to muddy particles and organic matter. The temporal sediments of metals declined with increased sediment depth, which reflects accumulation of trace metals since European settlement in this area. Furthermore, the source of the trace metals was found to be stormwater outlets, gasoline fumes, boatyards and other human activities.     

Distribution and contamination assessment of heavy metals in sediment of the Second Songhua River, China

The Second Songhua River was subjected to a large amount of raw or primary effluent from chemical industries in Jilin city in 1960s to 1970s, resulting in serious mercury pollution. However, an understanding of other trace metal pollution has remained unclear. The objective of this study was to investigate trace metal contamination in the sediment of the river. Bottom sediment samples were taken in the river between Jilin city and Haerbin city in 2005. An uncontaminated sediment profile was taken in the Nen River at the same time. Total concentrations of Al, Fe, Mg, Ca, K, Na, Ti, Mn, V, Sc, Co, Cu, Cr, Ni, Pb and Zn in the sediment samples were measured by ICP-MS or ICP-OES, following digestion with various acids. Concentrations of Co, Cu, Cr, Ni, Pb and Zn in the surface sediments were 5.1–14.7, 18.5–78.9, 2.4–75.4, 7.2–29.0, 13.5–124.4, and 21.8–403.1 mg/kg, respectively, generally decreasing along the course of the river from Jilin city to Haerbin city. Background concentrations of trace metals were reconstructed by geochemical normalization to a conservative element scandium. Results showed that concentrations of Co, Cr, and Ni in the sediment were generally only slightly higher than or equal to their background values, while concentrations of Cu, Pb, and Zn in the some sediment samples were significantly higher than their background values. In detail, the sediment at Jilin city was moderately contaminated by Cu, and the sediment of the Second Songhua River was moderately contaminated by Pb and Zn. The top layer (0–10 cm depth) and bottom layers (30–46 cm depth) of one sediment profile at Wukeshu town were generally moderately polluted by Pb and Zn. Synthetically, the surface sediment in the studied river section was classified as natural sediment without ecological risk by the sediment pollution index (SPI) of Cu, Cr, Ni, Pb and Zn. Only the 30–45 cm depth of the sediment profile at Wukeshu town was classified as low polluted sediment by the SPI of these metals, recording a historical contamination of the river in the 1960s to 1970s. This buried contamination of trace metals might pose a potential risk to water column under disturbance of sediment. Foundation item: The National Basic Research Priorities Program of China (2004CB418502)     

An assessment of metal contamination risk in sediments of Hara Biosphere Reserve,southern Iran with a focus on application of pollution indicators

The aim of this study was to assess the pollution status of metals in sediments of Hara Biosphere Reserve using pollution indicators. For this purpose, sediment samples from nine locations were collected and characterized for metal content (Pb, Cr, Zn, Cu, and Fe) using the total digestion technique. Comparison of metal concentrations with that of sediment quality guidelines (SQGs) demonstrated no association with negative biological effects for Cu and Zn, while the values of Pb and Cr mainly illustrated to have association with negative biological effects. The results of the geo-accumulation index (I _geo) indicated no contamination for Cr, Cu, Zn, and Fe, while the values of Pb demonstrated to have moderate contamination based on I _geo values. The analysis of the enrichment factor (EF) showed no enrichment for Cu and Zn and minor enrichment for Pb and Cr. Similar results were also found for quantification of contamination (QoC) analysis, where the values of Cu and Zn demonstrated to have a geogenic source of contamination, while the values of Pb and Cr mainly illustrated to have an anthropogenic source of contamination. According to EF and QoC calculations, the values of Cu and Zn were derived mainly from natural processes and exposure of material from the earth’s crust, while the values for Pb and Cr were enriched by anthropogenic activities. The results of the contamination factor (C _f ⁱ ) demonstrated low contamination levels for Fe, Cr, Zn, and Cu and moderate contamination levels for Pb. The pollution load index (PLI), showing the overall contamination of metals, demonstrated moderate pollution status in the study area.     

Metal pollution records in core sediments of some Red Sea coastal areas, Kingdom of Saudi Arabia

In the last three decades, the industrial and human activities in the coastal area of Saudi Arabia have increased dramatically and resulted in the continuous invasion of different types of pollutants including heavy metals. Seven sediment cores were collected from three major industrialized areas; Jeddah, Rabigh and Yanbu, along the coast of Saudi Arabia to determine the spatial and temporal distribution of metals and to assess the magnitude of pollution and their potential biological effects. Sediments were analyzed for texture, calcium carbonate contents, organic matter and metals (Al, Fe, Mn, Cd, Cr, Cu, Ni, Pb and Zn). Some metals like, Cr, Mn, Ni and Zn, were enriched in the upper 15 cm of core samples (recent deposition of sediments). Cadmium concentrations showed high fluctuations with depth and reverse pattern to that for Al, Fe and Mn which indicated land based sources of this element to the studied areas. Elevated concentrations of lead were recorded in the bottom layers of cores in Jeddah that indicated the most dramatic increase in usage of gasoline in early 1970s. The calculated contamination factors (CF's) were found in the following sequences: Cd > Pb > Ni > Cu > Zn > Cr > Mn for all studied areas. Results of Pollution Load Index (PLI) revealed that Jeddah is the most polluted area, followed by Rabigh while Yanbu is the least contaminated area. Except for Ni, the concentrations of most metals in the majority of sediment samples were believed to be safe for living organisms. As no data were available on the concentration of metals in core sediments in the coastal area of Saudi Arabia, the results of this study would serve as a baseline against which future anthropogenic effects can be assessed.     

Evaluation of potentially toxic metals pollution in the sediments of the Kor river, southwest Iran

This study is carried out to evaluate potentially toxic metal concentrations (As, Cd, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) together with their spatial distribution, degree of pollution, and potential ecological risk in Kor river sediments (southwest Iran) using sediment quality guidelines, geoaccumulation index (I _geo), Hakanson potential ecological risk index (RI), and standard methods of statistical analysis. The study area stretches some 140 km from the Drodzan Dam to Bakhtegan Lake, a stretch of river where different industrial and domestic activities (e.g., petrochemical complex, oil refinery, industrial meat processing complex, Marvdasht city sewage) and ecological value overlap with each other. Calculated geoaccumulation index indicate that 50 % of the stations are moderately to very extremely polluted. The potential ecological risk for nine investigated metals in Kor river is Hg (948)?>?Mo (51.9)?>?Ni (37.8)?>?Cd (29.8)?>?As (22)?>?Cu (16.6)?>?Pb (13.3)?>?Zn (3.3)?>?Cr (1). Results show that sediments in parts of Kor river sediments are heavily affected by effluents discharged from industrial plants and other parts are affected by agriculture and urban runoff from nearby lands. These phenomena may cause a risk of secondary water pollution under sediment disturbance and/or changes in the physical–chemical characteristics of the aquatic system.     

Contamination assessment of arsenic and heavy metals in a typical abandoned estuary wetland—a case study of the Yellow River Delta Natural Reserve

Coastal and estuarine areas are often polluted by heavy metals that result from industrial production and agricultural activities. In this study, we investigated the concentration trait and vertical pattern of trace elements, such as As, Cd, Ni, Zn, Pb, Cu, and Cr, and the relationship between those trace elements and the soil properties in coastal wetlands using 28 profiles that were surveyed across the Diaokouhe Nature Reserve (DKHNR). The goal of this study is to investigate profile distribution characteristics of heavy metals in different wetland types and their variations with the soil depth to assess heavy metal pollution using pollution indices and to identify the pollution sources using multivariate analysis and sediment quality guidelines. Principal component analysis, cluster analysis, and pollution level indices were applied to evaluate the contamination conditions due to wetland degradation. The findings indicated that the concentration of trace elements decreased with the soil depth, while Cd increases with soil depth. The As concentrations in reed swamps and Suaeda heteroptera surface layers were slightly higher than those in other land use types. All six heavy metals, i.e., Ni, Cu, As, Zn, Cr, and Pb, were strongly associated with PC1 (positive loading) and could reflect the contribution of natural geological sources of metals into the coastal sediments. PC2 is highly associated with Cd and could represent anthropogenic sources of metal pollution. Most of the heavy metals exhibited significant positive correlations with total concentrations; however, no significant correlations were observed between them and the soil salt and soil organic carbon. Soil organic carbon exhibited a positive linear relationship with Cu, Pb, and Zn in the first soil layer (0–20 cm); As, Cr, Cu, Ni, Pb, and Zn in the second layer (20–40 cm); and As, Cr, Cu, Ni, Pb, and Zn in the third layer (40–60 cm). Soil organic carbon exhibited only a negative correlation with Cd (P?I _geo values), which averaged less than 0 in the three soil layers, this finding indicates that the soils have remained unpolluted by these heavy metals. The mean concentrations of these trace elements were lower than Class I criteria. The degradation wetland restoration suggestions have also been provided in such a way as to restore the reserved flow path of the Yellow River. The results that are associated with trace element contamination would be helpful in providing scientific directions to restore wetlands across the world.     

An assessment of metal pollution in surface sediments of Seyhan dam by using enrichment factor, geoaccumulation index and statistical analyses

The aim of this study was to determine if high concentrations of any heavy metals exist in the sediment of Seyhan Dam reservoir to be considered toxic to the aquatic environment. Surface sediment samples from five stations in the Seyhan dam were collected quarterly from 2004 to 2005 and examined for metal content (Cr, Zn Cu, Mn, Cd, Fe, Ca, K, and Na), organic matter, and grain size. Correlation analyses showed that metal content of Seyhan dam sediment was affected by organic matter and grain size. The results have been compared with values given in the literature. The evaluation of the metal pollution status of the dam was carried out by using the enrichment factor and the geoaccumulation index. A comparison with sediment quality guideline values has also been made. Based on the enrichment factor, dam sediments were treated as a moderately severe enrichment with Cd and minor enrichment with Cr and Mn. The results of geoaccumulation index reveal that sediments of Seyhan Dam were strongly polluted in stations 1, 2, 4, and 5, and were moderately polluted in station 3 with Cd. Moreover, Cd and Cr concentrations in the sediments were above TECs except ERL for Cd.     

Determination of toxic elements in waters and sediments from River Subin in the Ashanti Region of Ghana

Waters and sediments of Subin River, which flows through the industrial and commercial areas of Kumasi in the Ashanti region of Ghana, were geochemically investigated to ascertain heavy metal pollution levels due to anthropogenic activities. The study shows preoccupying pollution levels that constitute a threat to public and ecological systems. The waters of Subin River are neutral to slightly basic, inferred from pH values of 6.89–7.65). Electric conductivity (EC) of the waters ranges from 822 to 1,821 μs/cm and the range of total dissolved solids (TDS) is from 409 to 913 mg/l. Toxic elements contents of sediments and waters from 10 sites along the river were analysed by instrumental neutron activation analysis (INAA), and Al, As, Cd, Cr, Cu and Zn were determined. The concentrations of Al, As, Cd, Cr, Cu and Zn in the waters range between 4.02–15.18, 0.007–0.16, 0.002–0.05, 0.001–0.019, 1.32–7.04 and 4.28–10.2 mg/l, respectively. The contamination factors (CF) computed for the elements indicate that with the exception of sampling site S10, the sediments are polluted with Cd. Chromium contamination in the sediments is observed at S6 and S7, where the CF values were 1.39 and 1.52, respectively. The pollution load indices (PLI) were low (<1) and ranged from 0.14 to 0.75, suggesting that the overall sediment column of the river is not polluted.     

Determination and speciation of heavy metals in sediments of the Juru River,Penang, Malaysia

The Juru River flows through largely urbanized areas and is grossly polluted by domestic wastes and discharges from pig farms. Other than carrying highly polluting organic materials, these wastes are also contaminated with heavy metals. To ascertain the extent of heavy metal pollution in the river, total and non-residual concentrations of Cu, Pb, Zn, Mn and Fe in sediment samples collected along the river were determined. The results indicate that both the total and non-residual metal concentrations in sediments can successfully be used to identify heavy metal pollution sources. The speciation of Zn, Mn and Fe in the sediment samples were investigated using a sequential leaching technique which identifies the elements among six operationally defined host fractions: (1) exchangeable, (2) carbonate and surface-associated, (3) easily reducible, (4) moderately reducible, (5) bound to organic matter and sulphides and (6) residual. The results indicate that Zn is mainly associated with the reducible fractions. Zn and Fe found in the moderately reducible fraction are significantly correlated, indicating that iron oxides is the preferred host phase by Zn.     

珠江口黄茅海表层海水和沉积物中重金属的分布及评价

根据2014年4月对珠江口黄茅海海域表层海水和沉积物中重金属分布的调查监测,采用单因子指数法、内梅罗指数法和生态危害指数法对其重金属污染水平进行评价。结果显示:该海域表层海水中部分站位的Pb、Cu、Zn和Hg超出第一类海水水质标准,内梅罗指数评价表明其整体处于轻污染水平。表层沉积物中部分站位的Hg、As和Cu超出第一类海洋沉积物质量标准,内梅罗指数评价表明其整体处于重污染水平,生态危害指数评价表明其整体可能面临中度风险,Hg为主要风险因子。表层海水中Pb、Cu、Zn具有同源性,表层沉积物中Pb、As、Zn和Cu具有同源性。     

Metal Pollution Assessment of Sediment and Water in the River Hindon, India

The metal pollution in water and sediment of the River Hindon in western Uttar Pradesh (India) was assessed for Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The metal concentrations in water showed wide temporal variation compared with bed sediment because of variability in water discharge and variations in suspended solid loadings. Metal concentrations in bed sediments provided a better evaluation of the degree and the extent of contamination in the aquatic environment, Santagarh and Atali being the most polluted sites of the river. The ratio of heavy metals to conservative elements (Fe, Al, etc.) may reveal the geochemical imbalances due to the elevated metal concentrations normally attributed to anthropogenic sources. Metal/Al ratios for the bed sediments of the river Hindon were used to determine the relative mobility and general trend of relative mobility occurred Fe > Mn > Zn > Cr > Ni > Pb > Cu > Cd.     

Paleolimnological assessment of Grove and Plow Shop Ponds, Ayer, Massachusetts, USA--a superfund site

Three sediment cores from each of severely polluted Grove and Plow Shop Ponds, Ayer, Massachusetts, USA, were dated using (210)Pb, characterized for plant macrofossil assemblages, and analyzed for H(2)O, loss-on-ignition, stable Pb isotopes, and concentrations of As, Ca, Cd, Cr, Cu, Fe, Hg, methyl-Hg, Ni, Pb, and Zn. A core from nearby kettle Spectacle Pond, Littleton, Massachusetts, was similarly characterized (except for plant macrofossil assemblages) to assess the regional air pollution signal in sediment for comparison with the six cores. Accumulation rates for metals (mass per area per year), the anthropogenic component (mass per area per year), and total accumulation of the anthropogenic component (mass per area) indicate that As, Cd, Cr, Cu, Hg, methyl-Hg, Ni, Pb, and Zn have accumulated in sediment as a consequence of point source pollution from within the drainage basins of Grove and Plow Shop Ponds. Three distinct sources of pollution are inferred. As is entering Plow Shop Pond via groundwater in the southwest. Cd, Ni, Pb, and Zn are entering the system predominantly at the eastern end of, or upstream from, Grove Pond. Pb also comes from the northwest corner of Grove Pond, the principal source of Cr, Cu, and Hg. These results are consistent with chemistry of modern surface sediments. The history of pollution extends back more than 100 years. Intra- and inter-core variability of concentrations and accumulation rates indicate that much of the pollution was likely in particulate form with little physical redistribution. Recently, concentrations and accumulation rates have generally decreased substantially for those elements present in excessive concentrations in the past. This is a consequence of accumulation of recent, less polluted sediment. In Spectacle Pond, the nearby reference lake, accumulation rates for As, Cd, Hg, and Pb, adjusted for background values and changes in sedimentation rate, increased above background starting in the late 19th century, peaked about 1980, and declined substantially to 2000. These decreases suggest that the anthropogenic (pollution) component of atmospheric deposition of these elements declined after 1980 by at least 50%(As), 80%(Cd), 80%(Hg), and 80%(Pb).     

Ecological risk assessment of heavy metals in surface sediments of northern littoral zone of Lake Çıldır,Ardahan, Turkey

In this paper, the heavy metal levels (Cu, Pb, Zn, Ni, Mn, Fe, As, Cd, Cr, Hg), organic carbon, and chlorophyll degradation products were studied to prove their ecological effects in Lake Ç?ld?r, where fossil fuels are used as an energy source in the studied area for most of the year, and domestic waste from settlements is discharged directly into the lake. Sediment samples were collected from six sites on the northern shore of Ç?ld?r Lake, Turkey in November 2012. Enrichment (EF) and contamination factor (CF) values were determined, and Pollution Load (PLI) and Potential Ecological Risk (PER) indices were calculated. Average concentrations of heavy metals in the sediments were, in descending order, Fe?>?Mn?>?Zn?>?Ni?>?Cr?>?Cu?>?Pb?>?As?>?Cd?>?Hg, respectively. According to mean values, the source of these elements may be considered natural due to lack of enrichment in Cu, Pb, Zn, Ni, and Cr in the sediment samples. Regarding enrichment of As, Cd, Mn, and Hg, the highest EF belongs to Hg. PLI and PER values indicate there are moderate ecological risk in the lake.     

Source discrimination of heavy metals in sediment and water of To Lich River in Hanoi City using multivariate statistical approaches

The concentrations of Mn, Fe, Ni, Cr, Cu, Pb, Zn, As, and Cd were determined to evaluate the level of contamination of To Lich River in Hanoi City. All metal concentrations in 0–10-cm water samples, except Mn, were lower than the maximum permitted concentration for irrigation water standard. Meanwhile, concentrations of As, Cd, and Zn in 0–30-cm sediments were likely to have adverse effects on agriculture and aquatic life. Sediment pollution assessment was undertaken using enrichment factor and geoaccumulation index (I _geo). The I _geo results indicated that the sediment was not polluted with Cr, Mn, Fe, and Ni, and the pollution level increased in the order of Cu < Pb < Zn < As < Cd. Meanwhile, significant enrichment was shown for Cd, As, Zn, and Pb. Cluster and principal component analyses suggest that As and Mn in sediment were derived from both lithogenic and anthropogenic sources, while Cu, Pb, Zn, Cr, Cd, and Ni originated from anthropogenic sources such as vehicular fumes for Pb and metallic discharge from industrial sources and fertilizer application for other metals.