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1.
The concentrations of heavy metals (Cr, Co, Ni, Cu, Zn, Pb, Cd, As, Hg, and Fe) in sediments of the Yangtze River, China, were investigated to evaluate levels of contamination and their potential sources. The lowest heavy metal concentrations were found in the source regions of the river basin. Relatively high concentrations of metals, except Cr, were found in the Sichuan Basin, and the highest concentrations were in the Xiangjiang and Shun’anhe rivers. All concentrations, except Ni, were higher than global averages. Principal component analysis and hierarchical cluster analysis showed that Zn, Pb, As, Hg, and Cd were derived mainly from the exploitation of various multi-metal minerals, industrial wastewater, and domestic sewage. Cu, Co, and Fe were derived mainly from natural weathering (erosion). Cr and Ni were derived mainly from agricultural activities, municipal and industrial wastewater. Sediment pollution was assessed using the geoaccumulation index (I geo) and enrichment factor (EF). Among the ten heavy metals assessed, Cd and Pb had the highest I geo values, followed by Cu, As, Zn, and Hg. The I geo values of Fe, Cr, Co, and Ni were <0 in all sediments. EF provided similar information to I geo: no enrichment was found for Cr, Co, and Ni. Cu, Zn, As, and Hg were relatively enriched at some sites while Cd and Pb showed significant enrichment.  相似文献   

2.
Street dust is one of the important indicators that reflect the status of urban environmental pollution. There are many studies of heavy metals contamination of street dust in capital cities; however, little attention has been paid to this kind of study in medium cities, including China. The dust samples were collected in the district of traffic crossroads in Xianyang city, Shaanxi Province. Pb, Cd, Cu, Ni, Zn, Cr and Mn concentrations were determined using atomic absorption spectrometry (AAS). The results indicate that the concentrations of heavy metals are higher than the background values of soils in Shaanxi Province. The contamination level of heavy metals is assessed by potential ecological risk index (E r), geoaccumulation index (I geo), enrichment factor (EF) and pollution index (Pi). The low I geo, EF, E r, Pi and PIn (integrated pollution index) for Mn in street dusts indicate an absence of distinct Mn pollution. The high EF, Pi and PIn of Cu and Zn indicate that there is considerable Cu and Zn pollution. It is suggested that more attention should be paid to heavy metals contamination of Cu and Zn. The assessment results of Pi and PIn suggest that Pb, Ni and Cr present strong pollution; however, their EFs indicate that they cause moderate pollution and their I geo indicates that they are unpolluted to moderately polluted. The contamination class value with different assessing methods is of the order: Pi ≈ PIn > EF > I geo > E r.  相似文献   

3.
In the present study, roadside-deposited sediment samples collected from Kuwait city district, in Kuwait, were analyzed for specific heavy metals (As, Cr, Cu, Mn, Ni, Pb, and Zn). Contamination assessment status of heavy metals in roadside sediments was made using mathematical models in terms of enrichment factor (EF), geoaccumulation index (I geo), and contamination factor (CF). The sediments showed remarkably high levels of all the metals, except Ni, above background concentrations in the following order (As, Cu, Pb, Zn, Mn, and Cr). CF and I geo revealed overall moderately uncontaminated and moderate contamination, respectively, but the EFs for all metals ranged between moderate and significant enrichment.  相似文献   

4.
Heavy metals are constantly emitted into the environment and pose a major threat to human health, particularly in urban areas. The threat is linked to the presence of Cd, Cr, Cu, Ni, Pb, and Zn in street dust, which consists of mineral and organic particles originating from the soil, industrial emitters, motor vehicles, and fuel consumption. The study objective was to determine the level of street dust contamination with trace metals in Lublin and to indicate their potential sources of origin. The analyses were carried out with an energy-dispersive X-ray fluorescence spectrometer. The sampling sites (49) were located within the city streets characterised by varying intensity of motor traffic. The following mean content values and their variation (SD) were determined: Cd: 5.1?±?1.7 mg kg?1, Cr: 86.4?±?23.3 mg kg?1, Cu: 81.6?±?69.2 mg kg?1, Ni: 16.5?±?3.9 mg kg?1, Pb: 44.1?±?16.4 mg kg?1, and Zn: 241.1?±?94.6 mg kg?1. The level of pollution was assessed with several widely used geochemical indices (geoaccumulation index, enrichment factor, pollution index, index of ecological risk, and potential ecological risk index). For most of the indices, the mean (median) values are arranged in the following manner: Zn?>?Cu(or Cd)?>?Pb?>?Ni?>?Cr. In general, street dust in Lublin does not show pollution with Cr, Ni, and Pb. Igeo and EF indices show moderate levels for Cu, Cd, and Zn; their presence in street dust is linked with anthropogenic factors (motor traffic). A significant threat is posed by Cd, and more than half of the samples show considerable pollution with cadmium (median for the index of ecological risk: 151). The spatial pattern of indices and the results of statistical analyses (CA, PCA) indicate three groups of elements: (1) Cr and Ni: natural origin; (2) Pb: mixed origin; and (3) Cd, Cu, and Zn: anthropogenic origin (mainly motor vehicle traffic). Higher content values for metals of anthropogenic origin in street dust indicate that it is a source of pollution of soil and air in the city.  相似文献   

5.
The study was taken up to establish the distributions of metals as well as to assess the extent of anthropogenic inputs into the Subarnarekha River. Bed sediments were collected; analyzed for metals; and assessed with the index of geo-accumulation (I geo), enrichment factor (EF) value, concentration factor (CF) and pollution load index (PLI). Metals in the sediment were variable in the river and there are major pollution problems at certain locations. The average concentrations of Fe, Cu, Cr, Pb, Mn, Ni, Zn, Co and Ba in mg/kg was found to be 30,802 ± 11,563, 69 ± 57, 111 ± 74, 75 ± 61, 842 ± 335, 42 ± 22, 100 ± 39, 15 ± 4 and 698 ± 435, respectively. The I geo, EF, CF and PLI indices showed that the contamination of Pb and Cu was more serious than that of Ni, Zn, Co and Ba, whereas the presence of Fe, Mn and Cr might be primarily from natural sources. The contamination of the sediments with metals at few locations is attributed to mining, industries and other anthropogenic causes. Principal component analysis was employed to better comprehend the controlling factors of sediment quality. The statistical analysis of inter-metallic relationship revealed the high degree of correlation among the metals indicated their identical behaviour during transport. PCA outcome of three factors together explained 83.8 % of the variance with >1 initial eigenvalue indicated both innate and anthropogenic activities are contributing factors as source of metal profusion in Subarnarekha River basin.The overall study reveals moderately serious pollution in the river basin principally in some locations under the anthropogenic influences.  相似文献   

6.
Concentrations of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in campus dust from kindergartens and elementary schools in Xi’an, China, were analyzed using X-ray fluorescence spectrometry and heavy metal contamination levels were assessed based on the geoaccumulation index (I geo), enrichment factor (EF) and numero synthesis pollution index (NSPI). The results indicate that, in comparison with Shaanxi soil, dust samples have elevated metal concentrations as a whole, except for V, Mn, Ni, and As. The assessment results of I geo and EF indicate that V, Mn, Ni, and As in campus dust are uncontaminated, while Ba and Cr are uncontaminated to moderately contaminated, and Co, Cu, Pb, and Zn are moderately to strongly contaminated. The NSPI results show that most dust samples presented heavily contaminated by heavy metals. More attention should be paid to heavy metal contamination of campus dust from kindergartens and elementary schools of Xi’an.  相似文献   

7.
The sediments of the raw sewage-fed fishpond system at East Kolkata Wetland (EKW) were analyzed for heavy metal content in a comprehensive way. Various indices of contamination like enrichment factor (EF), geo-chemical index (I geo), modified degree of contamination (mDC), and pollution load index (PLI) were assessed. In all cases, instead of literature values, the metal concentrations of less contaminated sites, separated by the statistical approach of the hierarchical cluster analysis, were used as baseline values. In the present study, about 70% of the pond sediments are found uncontaminated, 5% display low degree of contamination and 25% are designated as moderate degree of contamination. Both the EF and I geo indices highlighted that the metals lead (Pb), cadmium (Cd), and chromium (Cr) are responsible for the contamination while there is little anthropogenic input in cases of Cu, Zn, and Ni. Most of the ponds situated near the main sewage flowing canals as well as the main traffic highway and close to the solid waste dumping areas recorded higher degree of metal contamination as evident from spatial variation of mDC and PLI indices in the study area. Indices comparison study clearly indicates that although these are calculated using different methods, these may or may not produce the same indices values and hence the values should neither be compared nor be averaged. But all the above indices are directly related to a common term contamination factor (CF). Classification of contamination levels based on these CF values is found to be similar and this classification is only valid up to the level of high degree of contamination. Thus, the use of any one of these indices is sufficient to classify the degree of contamination of an area. However, to evaluate the contamination per metal, both I geo and EF are effective while, to assess the composite effect of all the metals, PLI is preferable to mDC.  相似文献   

8.
This study reported the first comprehensive research on identification of metal concentrations (Fe, Mg, Mn, Pb, Cd, Cr) in order to provide baseline data for future studies, identify possible sources, determine degree of pollution, and identify potential ecological risks of metals in surface sediments from Iran’s Choghakhor Wetland. The order of metal concentration was as follows: Fe > Mg > Mn > Pb > Cd > Cr, with mean concentrations of 6140.35, 1647.32, 289.03, 1.10, and 0.45 µg/g of dry weight, respectively. These results reveal that Choghakhor Wetland is not heavily polluted compared to other regions. The results of enrichment factor (EF) and geoaccumulation index (I geo) showed that Fe, Pb, Mg, Cr, and Mn presented low levels of contamination and probably originated from natural sources. On the other hand, the results of EF and I geo indices suggested that Cd concentrations in sediments of Choghakhor Wetland originated from anthropogenic sources. Based on the results of three sets of sediment quality guidelines, only Cd concentration in sediments of Choghakhor Wetland is a threat for aquatic organisms of Choghakhor Wetland. The results of multivariate analysis such as principal component analysis and cluster analysis showed that Fe–Mn, Cr–Mg, and Pb groups originated from natural sources, while Cd concentrations in sediments of Choghakhor Wetland originated from both natural and anthropogenic sources (mainly chemical fertilizers). To our knowledge, this is the first study about metal concentrations in sediments of Choghakhor Wetland, and because of low levels of these metals, these concentrations can be considered background levels for future investigation.  相似文献   

9.
Heavy metals are introduced in human tissue through breathing air, food chain and human skin. They can cause damage to the nervous system and internal organs. In the present study, sixty street dust samples were collected from the central area of Tehran and were digested in the laboratory to determine the content of Zn, Ni, Cd, Cr, Cu and Pb, using inductively coupled plasma optical emission spectrometry (ICP-OES). The level of contamination with the analyzed metals was determined according to the following indices: geo-accumulation index (I geo), enrichment factor (EF), pollution index (PI), integrated pollution index (IPI) and potential ecological risk index (RI). The average concentration of heavy metals found was in the order of Zn > Cu > Pb > Ni > Cr > Cd. The average I geo values for Cd, Cr, Cu, Ni, Pb and Zn were 1.53, ?1.88, 2.68, ?0.67, 1.62 and 2.70, respectively. Among the investigated heavy metals, zinc and copper had the maximum average EF values and were placed into the “very severe enrichment” class. Potential ecological risk factor (E r) also indicated that Cd had the highest risk, and it was classified as of considerable potential ecological risk. Therefore, it is necessary to pay more attention to the appearance of Cd in the human environment. The calculated potential ecological risk index values also illustrated that the street dust samples presented a “moderate ecological risk.” The calculated IPI values showed that the pollution levels of the street dust samples ranged from high to extremely high.  相似文献   

10.
Socioeconomic developments and industrialization exert tremendous impact on beaches which is often neglected. Heavy metal (Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb) contents were estimated in the intertidal region from Kalpakkam to Mamallapuram (20 km), southeast coast of India covering seven locations. To evaluate the level of contamination of these metals; enrichment factor (EF), geoaccumulation index (I geo), contamination factor (CF), pollution load index (PLI) and modified degree of contamination (mCd) were applied. The results were also compared with the sediment quality guidelines (SQGs) to find out the eco-toxicity level. Metal contents in the beach sediment were observed in the order: Fe > Al > Mn > Cr > Cu > Ni > Zn > Pb > Co > Cd. Grain size distribution showed medium to coarse nature of the sediment. Significant positive correlation was found among the metals indicating their common source of input. Based on EF, minor enrichment of Mn and Zn and moderately severe to severe enrichment of Cr, Cu, Pb and Cd were observed which was further confirmed by I geo and CF values. Moreover, Mamallapuram showed a very high CF value for Cd (>6) indicating very high contamination accountable to anthropogenic sources. PLI and mCd in all the stations indicated unpolluted nature except M1 where the values pointed moderate degree of contamination. As per the SQGs, Ni and Cr values exceeded the probable effect limit value implying that these metals can have adverse impacts. None of the metals exceeded the effect range median indicating that the beach sediment is not very toxic.  相似文献   

11.
Farming is the major source of income for the villagers of North-central Sri Lanka. However, chronic kidney disease of unknown etiology is a major health hazard in the area and it is assumed that agricultural contaminants are the major causative agents. This study focuses on the geochemistry of soils in the area to determine possible natural and anthropogenic impacts of the problem. X-ray fluorescence analysis was used to determine the abundance of selected major and trace elements. Results show that geo-enrichment for many elements indicates slight to significant variations between agricultural and non-agricultural soils. Geoaccumulation index (I geo) shows higher pollution levels of Pb and V (2 < I geo < 3) and very lower pollution levels of As, Zn, Cu, Fe and Mn (1 < I geo < 2) in agricultural soils. However, I geo for non-agricultural soils implies lack of contaminations (I geo < 1). Positive correlations of As with Pb and Zn and negative correlations with Cu, Ni and Cr suggest that they may have derived from different sources such as sulfide minerals of basement rocks, fertilizers and agrochemicals. The results of this study suggest that there is no significant threat from As and other trace elements to soils. The accumulation of these elements in agricultural fields may have been effectively controlled by seasonal farming practices. However, there is a potential environmental risk from elements such as Pb and V due to their significant enrichment in soils.  相似文献   

12.
This article reports on the concentration of selected trace elements (Mn, Zn, Cr, Cu, Ba, As, B, V, and Hg) and major elements (Fe and Al) from the intertidal sediment cores from Sundarban wetland, India. This is a typical meso-macrotidal estuarine area affected by domestic and industrial activities located upstream. The overall concentrations range is low to moderate, indicating the environmental conditions in the outfall zone (grain size, hydrodynamic regime, and confinement), which favors the in situ accumulation of pollutants. The extent of contamination from trace elements in Sundarban core sediments is evaluated through a two-pronged approach: (i) by determining the metal enrichment in the sediments through the calculation of Pollution Load Index (PLI), Enrichment Factor (EF) and Index of Geoaccumulation (I geo), and (ii) by defining a potential level of biological risk by the use of quality criteria such as Threshold Effect Level (TEL) and Effects Range-Low (ERL) benchmarks. On the basis of the calculated indices, sediments are particularly enriched with Cr, Cu, B, V, and As. Those enrichments seem to be due to the fine granulometry of the regions with Fe and Mn oxi-hydroxides being the main metal carriers. Trace Elements input to the Sundarban wetland need to be kept under strict control in future specially with reference to As since, according to TEL and ERL benchmarks, it already appears to be associated with a potential biological risk.  相似文献   

13.
An elucidation of the background levels of heavy metals, including certain toxic elements, is very essential to accomplish an important environmental assessment. A regional geochemical mapping in Hokkaido, Japan was undertaken by the Geological Survey of Japan, AIST as part of a nationwide geochemical mapping for this purpose. There were 692 stream sediments collected from the active channel (1 sample) / (100 km2) in Hokkaido and the fine fraction sieved through a 180 μm screen was analyzed using the AAS, ICP-AES, and ICP-MS techniques. The regional geochemical maps for 51 elements were created as a 2000 m mesh map using the geographic information system software. Spatial distribution patterns of elemental concentrations in stream sediments, particularly Neogene–Quaternary volcanic and pyroclastic rocks, are primarily determined by surface geology. The correspondence of elemental concentrations in stream sediments to parent lithology is clearly indicated by ANOVA and a multiple comparison. Sediment samples supplied from mafic volcanic and felsic–mafic pyroclastic rocks are significantly rich in MgO, Al2O3, P2O5, CaO, Sc, TiO2, V, MnO, Total (T)-Fe2O3, Co, Zn, Sr, and heavy rare earth elements (REEs) (Y and Eu–Lu), but significantly lacking in alkali elements, Be, Nb, light REEs (La–Nd), Ta, Tl, Th, and U. Accretionary complexes with sedimentary rocks derived from sediments are in stark contrast to volcanic and pyroclastic rocks. Accretionary complexes with mafic–ultramafic rock have significantly elevated Nb, Ta, and Th abundances in sediments besides MgO, Cr, Ni, Co, and Cu. This inexplicable result is caused by the mixed distributions of granite and ultramafic–mafic rocks.The watersheds with mineral deposits relate to the high concentrations of certain elements such as Zn, As, and Hg. The geochemically anomalous pattern, which is a map of the regional anomalies, and a scatter diagram were applied to examine the contribution of mineral deposits to MnO, T-Fe2O3, Cr, Cu, Zn, As, Cd, Sb, Hg, Pb, and Bi concentrations. Consequently, they were grouped into four types: 1) Mineral deposits with no outliers resulting from mineralization (MnO, T-Fe2O3, and Cr), 2) sediments supplied from watersheds without metal deposits conceal high metal inputs from known mineral deposits (Cu), 3) deposits from a geochemically anomalous area that closely relates to the presence of mineral deposits (As, Sb, and Hg), and 4) deposits from the widely altered zone associated with the Kuroko as well as hydrothermal deposits corresponding to geochemically anomalous patterns (Zn, Cd, and Pb). This study provides an important regional geochemical database for a young island-arc setting and interpretational problems, such as complicated geology and active erosion, that are unique to Japan.  相似文献   

14.
The total concentrations of Cd, As, Pb, Cr, Ni, Co, Zn, Cu, Ag, Hg, and Mo were determined in the atmospheric dust of the city of Yerevan by atomic absorption spectrometry (AAnalyst PE 800). Heavy metal pollution levels were evaluated by calculating geo-accumulation (I geo ) and summary pollution (Zc) indices. Potential human health risk was assessed using the United States Environmental Protection agency’s human health risk assessment model. The results show that mean contents of all elements tested except Ni and Cr were substantially higher than local geochemical background values. According to the I geo , Yerevan territory is strongly-to-extremely polluted by As, Ag, Hg, Mo, and Cd. The Zc assessment indicated that very high pollution was detected in 36 % of samples, high in 32 %, average in 12 %, and low in 20 %. The health risk assessment revealed a non-carcinogenic risk (HI >1) for children at 13 samplings sites and for adults at one sampling site. For children the risk was due to elevated levels of Mo, Cd, Co, and As, while for adults, only Mo. Carcinogenic risk (>1:1,000,000) of As and Cr via ingestion pathway was observed in 25 and 14 samples, respectively. This study, therefore, is the base for further detailed investigations to organize problematic site remediation and risk reduction measures.  相似文献   

15.
Heavy metal accumulation due to industrial activities has become a very sensitive issue for the survival of the aquatic life. Therefore, distributions of several heavy metals have been studied in the surface sediments of Tapti–Hazira estuary, Surat, to assess the impact of anthropogenic and industrial activities near estuary. Totally 60 sediment samples were collected from four different sites at Tapti–Hazira estuary, Surat from January 2011 to May 2011 and examined for metal contents. The average heavy metal load in the study area are found to be 43.28–77.74 mg/kg for Pb, 48.26–72.40 mg/kg for Cr, 117.47–178.80 mg/kg for Zn, 71.13–107.82 mg/kg for Ni, 123.17–170.52 mg/kg for Cu, 0.74–1.25 mg/kg for Cd, 14.73–21.69 mg/kg for Co. Calculated enrichment factors (EF) reveal that enrichment of Pb and Cd is moderate at all sites, whereas other metals Cr, Ni, Zn, Co, and Cu show significant to very high enrichment. Geo-accumulation index (I geo) results revealed that the study area is nil to moderately contaminated with respect to Cd, moderately to highly polluted with respect to Pb, Zn, and Cu and high to very highly polluted with respect to Co and Cr.  相似文献   

16.
Trace metals were analyzed in water and sediment samples from Barapukuria coal mine area of Bangladesh in order to evaluate their mobility and possible environment consequences. Cadmium is the most mobile element with an average partition coefficient (log K d ) of 2.95 L/kg, while V is the least mobile element with a mean log K d of 5.50 L/kg, and their order of increasing mobility is: V < As < Pb < Fe < Cr < Se < Mn < Ni < Zn < Cu < Ba < Sr < Cd. Contents of organic carbon in sediment samples shows strong positive correlations with most trace metals as revealed by the multivariate geostatistical analysis. The overall variation in concentration is mainly attributed to the discharge of effluents originating from the coal mining activities around the study area. Compared to their background, Ni and Cu are the most enriched while significant enrichment of As, Mn, Ba, Sr, Cr, and Pb is also observed in the sediments. Geoaccumulation indices (I geo ) suggest sediments are moderately to heavily polluted with respect to Ni and Cu. The metal pollution index (MPI) varied from 91.91 to 212.01 and the highest value is found at site CM03 that is close to discharge point. The sediment quality guideline index (SQG-I Intervention ) values (0.56–1.52) suggest that the sediments at the study area have moderate to high ecotoxicological risk.  相似文献   

17.
Ten heavy metals, namely, Ag, As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn were partially extracted using aqua regia digestion method and analysed by ICP-AES from 56 stream sediment samples collected from River Orle, Igarra area, southwestern Nigeria. The analytical results were used to produce geochemical distribution maps for the elements and were subjected to univariate statistical analysis in order to evaluate the distribution and abundance of the heavy metals in the study area. The degree of pollution of these stream sediments by these heavy metals was evaluated by calculating such parameters as enrichment factors (EF), as well as pollution load and geo-accumulation indices (PLI and Igeo). Co, Cr, Cu, Ni, Pb and Zn are widely distributed in the drainage system while the distribution of Ag, Cd, As and Hg is restricted to only parts of the drainage system with Ag and Cd being localized to one sample site each near Epkeshi in the southern part of the study area. Cr and Pb display anomalously high concentrations, each from a site, also in the same locality where Ag and Cd were detected, indicating the likelihood that the four elements, Cr, Pb, Ag and Cd, are genetically related. Calculation of the enrichment factor (EF), pollution load index (PLI) and geo-accumulation index (Igeo) yielded results that indicate that all the 56 stream sediment sites, except one located about 4 km southeast of Epkeshi in the southern part of the Orle drainage system, are practically unpolluted by heavy metals. The relatively high metal concentration of this anomalous site having Pb EF of 62.5, PLI of 1.14 and Pb Igeo of 2.44 signifies Pb pollution. Both natural and anthropogenic sources of the Pb contamination around Epkeshi locality are possible. In conclusion, the levels of concentrations of heavy metals in the study area, in general, do not constitute any serious environmental risk except for Pb which needs to be monitored at only one site in the study area. Therefore the concentration ranges for the different heavy metals in the study area can serve as baseline environmental data against which the degree of pollution of these heavy metals can be evaluated in future.  相似文献   

18.
Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O3T suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C–S–Fe relationship owing to authigenic precipitation of Fe–Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.  相似文献   

19.
The present study was conducted on the Manasbal Lake (34°14′N: 74°40′E) to assess the geochemical characteristics of the lake bottom sediments, its environmental implications and its response in the local catchment area. This study tracks the spatial distribution of grain size, geochemical analysis, C/N ratio, calcium carbonate (CaCO3) and organic matter (OM) of the lake bottom sediments. It is observed that the clay fraction (49.79%) is predominant in the lake bottom sediments, followed by silt (35.88%) and sand (14.33%) and its spatial distribution is controlled by water depth. Geochemistry and normalized diagrams for the major oxides and trace elements reveal enrichment of CaO, K2O, P2O5, S, Cl, Ni, Zn and Sr. Chemical index of alteration (CIA) reflects low to moderate weathering intensity and near compositional similarity with the bedrock exposed in the catchment area around the lake. Environmental indices (EF, Igeo) suggest that the sediments are enriched in Cu, Ni, Zn, Cr, Co, Pb followed by Mn content. Pollution load index (PLI) reveal that all the sampling sites reflect low to moderately polluted category except for few stations that are towards the southern and southeastern side of the lake. OM (16.85%), CaCO3 (14.04%) and C/N ratio (15.5) of the lake bottom sediments is attributed to high organic activity within the lake, shell fragments, contributions from the lake flora and fauna adhering to the clayey silty sediments. The C/N ratio of 15.5 suggests a mixed source of organic matter both terrestrially and in situ formation within the lake. Sulphur and chlorine are high amongst the trace elements suggesting anthropogenic detritus input into the lake and this is due to the chemical fertilizers from the agricultural runoff and organic load into the lake. Thus, the present study suggests that in order to preserve the pristine lake ecology and the environment; continued monitoring and restoration efforts need to be undertaken.  相似文献   

20.
Analysis of ten heavy metals (Ag, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Zn) in six sediment cores from Wellington Harbour show both anthropogenic enrichments and diagenetic modifications. Absolute concentrations determined by two methods, x-ray fluorescence and acid leaching for bioavailability, are not comparable. However, vertical trends in concentrations of the cored sediment are comparable. To assess levels of anthropogenic pollution, enrichment factors (enriched concentrations in upper core divided by background levels in lower core) are preferred over index of accumulation (I geo) values because preindustrial or background levels of heavy metals are well constrained. The ten metals are placed into three groups: (1) Cu, Pb, and Zn, which show the most anthropogenic enrichment; (2) As, Cd, Cr, Ni, and Sb, which are often associated with anthropogenic pollution but show only minor enrichment; and (3) Fe and Mn, which are diagenetically enriched. Assuming harbor waters are well mixed, anthropogenic enrichments of Cu, Pb, and Zn, are time correlative, but the degree of enrichment depends on the method of analysis and core location. Levels of As, Cd, Pb, and Zn show small variations in preindustrial sediments that are not related to changes in grain size and probably result from changes in the oxidation-reduction potential of the sediments and salinity of the pore waters.  相似文献   

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