Heavy metal accumulation in the surficial sediments along southwest coast of India

Concentration and distribution of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) in surface sediments collected from five stations located along the southwest coast of India were investigated seasonally to assess whether there is insidious buildup of heavy metals. Spatial variation was in accordance with textural characteristics and organic matter content. The concentration of the metals in sediments of the study area followed the order: Zn > Cr > Ni > Cu > Pb > Cd > Hg. The use of geochemical tools and sediment quality guidelines to account for the magnitude of heavy metal contamination revealed high contamination in monsoon and impoverishment during post-monsoon. Estimated total metal concentrations in the present investigation were comparable with other studies; however, concentrations of Ni and Zn were higher than that of other coastal regions. Concentrations of metals in sediment largely exceed NOAA effects range:low (e.g., Cu, Cr, Hg) or effects range:median (e.g., Ni) values. This means that adverse effects for benthic organisms are highly probable.     

Status of sedimentation in King Talal Dam,case study from Jordan

This paper focuses on characterizing the current status of physical and chemical characteristics of King Talal Dam (KTD) sediments. The quality of sediments was investigated based on several international sediment quality guidelines. The volume of sediment and sedimentation rate in (KTD) was also estimated. Five types of granulometric textural facies were observed for the sediments of KTD reservoir bed, with an average grain size distribution of gravel (1.38%), sand (32.38%), silt (32.35%) and clay (32.38%). The fraction of <63 micron showed that the total mean size was 8.0 micron. Other sediment parameters in KTD were 7.0% for total organic matter (TOM), 7.3 for pH, 35.9% for CaCO₃ and 100.5 meq/100 g for cation exchange capacity, with dominant mineralogical constituents of quartz, calcite, dolomite, clay minerals and minor feldspar. The total concentrations of F, Cl, NO₂, NO₃, PO₄ and SO₄ in sediment samples were lower inward for KTD. The vast majority of trace metals in sediments were generally within the standard limits recommended for soils. TOM and grain size of sediment are major factors governing the trace metal concentrations. The calculated geoaccumulation index (I _geo) and enrichment factor of metals in bottom sediments showed that the metals were in the following order: Cd > Pb > Zn > Co > Cr > Ni > Fe > Cu > Sr > Mn and Cd > Zn > Pb > Co > Cr > Ni > Cu > Sr > Mn, respectively. Based on the sonic survey of KTD reservoir, the annual sedimentation rate was about 0.4061 MCM/year, in which about 18.66% of the reservoir initial storage capacity was lost to sediments and a projected lifespan of about 198 years.     

Distribution and enrichment of trace metals and arsenic at the upper layer of sediments from Lerma River in La Piedad,Mexico: case history

Lerma River is one of the largest rivers in Mexico. Over the past 20 years, unplanned population growth occurred along its course and the river has been used as the only outlet for industrial and domestic wastewater disposal. The aim of the present study was to determine trace metals such as Cr, Ni, Cu, Zn, Fe, Pb, and arsenic concentrations at the upper layer of sediments of the Lerma River meander in La Piedad, Michoacan, Mexico. Sediment samples were collected from eight different sites during the rainy and dry seasons. All samples were physically characterized, and concentration values of trace metals and As were determined. On the basis of protection criteria for freshwater sediments, concentrations of Fe, Zn, Cu, Ni, and Pb were found to exceed the lowest effect level; moreover, the concentrations were found to exceed the severe effect level at some sites, particularly for Cu. Statistical analyses showed significant differences between sampling seasons for Fe and As, and among sites for Ni, Cu, Zn, and Pb. In addition, the enrichment factor indicates the following order Zn > Cr > Cu > Ni > Pb > As, and the geoaccumulation index (I _geo) indicates contamination in the following order Zn > Cr > Cu > Ni > As > Pb. The Lerma River meander in La Piedad shows a reduction in pollution by trace metals and arsenic near the drain area and downstream of the meander. However, there are significantly higher concentrations of these elements in sediments of sites located in the middle part of the city.     

Assessment of spatial distribution and possible sources of heavy metals in the soils of Sariseki-Dörtyol District in Hatay Province (Turkey)

In this study, total heavy metal content of soil and their spatial distribution in Sar?seki-Dörtyol district were analyzed and mapped. Variable distance grids (0.5, 1.0 and 2.0 km) were established, with a total of 102 soil samples collected from two different soil depths (0–5 and 5–20 cm) at intersections of the grids (51 sampling point). Soil samples were analyzed for heavy metals (Cd, Co, Cr, Cu, Pb, Zn, Mn, Fe, and Ni). The most proper variogram models for the contents of all heavy metal were spherical and exponential ones. The ranges of semivariograms were between 1.9 and 31.1 km. According to the calculated geoaccumulation (I _geo) values, samples from both soil depths were classified as partly to highly polluted with Cd and Ni and partly polluted with Cr and as partly polluted-to-not polluted with Pb and not polluted with Cu, Fe and Mn. Similar results were also obtained when evaluated by the enrichment factor. The contamination levels of the heavy metals were Ni > Cd > Cr > Pb > Zn > Cu > Co > Fe > Mn in decreasing order. The soils in the study area are contaminated predominantly by Cd and Ni, which may give rise to various health hazards or diseases. Cadmium pollution results primarily from industrial activities and, to a lesser extent, from vehicular traffic, whereas Ni contents in the study area result from parent material, phosphorus fertilizer, industries, and vehicles.     

The contamination and transfer of potentially toxic elements and their relations with iron, vanadium and titanium in the soil-rice system from Suzhou region, China

A regional scale investigation was performed to study the contamination and transfer of Ni, Cr, Co, Al, Cd and Hg and their relations with Fe, V and Ti in the soil-rice system under actual field conditions from a typical developed industrial area. Thirty-two pairs of rice and soil samples were collected in Suzhou region, China. The results show that the transfer abilities of potentially toxic elements (PTEs) were generally in the order of Cd > Hg > Co > Ni > Cr > Al from soil to root, Hg > Cr > Al > Ni > Cd > Co from root to straw and Ni > Hg > Cr > Cd > Al > Co from straw to grain. Compared with the relevant criterion, the major pollutants in rice grains were Al and Ni. 18.8 and 12.5 % of grain samples were contaminated by Al and Ni, respectively. Besides the increased soil PTEs concentrations, the enhanced transfer of Ni and Al from rice root to grain via straw may play another crucial role in Ni and Al contamination of rice grain. The relatively weaker transfer ability of Co in the rice plant may be conducive to the rice grain keeping an uncontaminated level of Co. Additionally, Al, Ni, Cr and Co showed high correlations with each other, and they also had a close association with Fe, V and Ti in soil and rice. These correlations imply that Fe, V and Ti may play an important role in the transfer, accumulation and speciation of Al, Ni, Cr and Co in the soil-rice system.     

Dispersion model and bioaccumulation factor validating trace metals in sea bream inhabiting wastewater drain outfalls

Our study was based on the recent increase in wastewater pollution and its deleterious effects to the marine ecosystem. Using numerical simulation (DESCAR-3.2 software program), we investigated the orientation and quantification of trace metals in wastewater discharges from permanent and semi-permanent drain outfalls constructed along the Kuwait Coastline encompassing six Kuwait Governorates (GI-GVI). This study was related to trace metals toxicity and bioaccumulation effects on the commercial yellow fin Sea bream, Acanthopagrus latus fish using probit program and bioaccumulation factor (BAF), respectively. Observations from wastewater discharges showed high trace metals concentrations in the sequence of Zn > Cr > Cu > Fe > Ni > Pb > Hg during winter compared to summer and in GI and GIV compared to drain outfalls in the other Governorates. Seasonally, trace metals in A. latus revealed the sequence of Zn > Fe > Cu > Ni > Cr > Pb > Hg in GI, GII and GIV indicating the significance of toxic metals that bioaccumulated from their surrounding untreated wastewater. Toxicity test revealed A. latus highly sensitive to Hg even at low lethal concentrations (LC₁₅) compared to other metals. BAF in A. latus body parts was >1 indicating significant accumulation of trace metals from wastewater. However, BAF was <1 in Cr suggesting that A. latus could absorb trace metals from multiple sources over lengthy exposure period and not necessarily from wastewater containing rich Cr levels. Thus, the present findings validate A. latus as bioindicator to pollution more authentically by numerical simulation, toxicity and bioaccumulation tests compared to the traditional method of labeling A. latus as a pollution indicator.     

Heavy metal exposure from co-processing of hazardous wastes for cement production and associated human risk assessment

This study was carried out to determine the concentration of heavy metals (Cd, Ni, Pb, Cr, Ni and Zn) in ordinary Portland cement (OPC) produced from the co-processing with hazardous waste in comparison with OPC produced using natural raw materials. The results showed that the concentration of heavy metals in cement produced from natural raw material was in the order of Zn > Pb > Cr > Ni > Cu > Cd. Zn and Cd were the highest and the lowest concentrations, respectively, in cements produced from the co-processing activity. The difference between heavy metals concentrations in OPC produced with and without co-processing was found to be statistically significant. The concentration of heavy metals in the cement produced is generally factory dependent. The human risk assessment associated with the heavy metals for non-carcinogenic and carcinogenic risks has been evaluated. The calculated hazard index (HI) and total lifetime cancer risks (LCR) were lower than the acceptable threshold reference values, HI < 1 and LCR < 1 × 10^?4, respectively. Thus, it is anticipated that there is no potential of non-carcinogenic and carcinogenic risks for both adult and children. However, the findings indicated that there is a need for regulatory monitoring. The exposure pathway for both non-carcinogenic and carcinogenic risks are both in the order of ingestion > dermal > inhalation.     

Toxic metal contamination and distribution in soils and plants of a typical metallurgical industrial area in southwest of China

In this work, the total and each fraction concentration of toxic metals (Pb, Zn, Cu and Cd) in soils as well as in plants from a typical metallurgical industrial area in southwest of China were determined. The obtained experimental results demonstrated that the total toxic metal content in contaminated soils was in the order of Zn > Pb > Cu > Cd. Modified microwave-assisted extraction showed that the distributions of each fraction of toxic metals in soils were different and some soil properties may play a role in the fraction distributions. The content of Cu, Zn, Cd and Pb in different vegetables ranged from 9.82 ± 1.02 to 39.3 ± 1.13 mg kg^?1, 1,321 ± 10.50 to 3,153 ± 11.30 mg kg^?1, 4.47 ± 0.21 to 18.9 ± 0.37 mg kg^?1 and 28 ± 1.2 to 102 ± 1.5 mg kg^?1, respectively. And the accumulation of toxic metals in plants was in the order of Cd > Zn > Cu > Pb. The bioconcentration factor (BCF) values of Cd, Zn, Cu and Pb in the different tissues of plants were in the range of 0.03–0.43, 0.027–0.35, 0.014–0.12 and 0.004–0.051, respectively. The distribution of each toxic metal in plants indicated that the ability for plants to accumulate toxic metals in different tissues followed the sequence of leaf > stem.     

Composition of selected heavy metals in road dust from Kuala Lumpur city centre

This study was carried out in order to determine the concentration of heavy metals, e.g., lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), nickel (Ni) and chromium (Cr) in road dust in Kuala Lumpur’s city centre. Samples were collected from four sampling locations, each of which had four sampling points and three replications. Heavy metals from different fractions of particles separated by different diameter sizes: d < 63 μm (Fraction A), 63 < d < 125 μm (Fraction B) and 125 < d < 250 μm (Fraction C) were analyzed using inductively coupled plasma mass spectrometry. The results from this study showed that concentration of heavy metals was dominated by the smallest particle size: <63 μm and that Fe was the most abundant heavy metal overall, followed by Cu > Mn > Zn > Pb > Ni > Cr > Cd. The fact that Cd had the highest enrichment factor value (EF) for all particle sizes indicates that anthropogenic activities contributed to the presence of this metal. There was also a higher EF value for heavy metals in small particle (Fraction A), compared to Fraction B and C, which suggests that fine particles were being produced through anthropogenic activities. Cluster analysis and principal component analysis demonstrated the likelihood of the heavy metals detected in the road dust, originating from road traffic and industrial activities.     

Investigation of metal pollution in Moryayla (Erzurum) and surrounding stream sediments,Turkey

The enrichment factor (EF), geochemical index (Igeo), pollution factor (Cf), and pollutant load index (PLI) were calculated using average shale metal concentration values to determine metal pollution in Moryayla and surrounding stream sediments. It was determined that the average concentration values are above the world average shale values. According to the results obtained, the mean accumulation levels of heavy metals in the study area were Mn > Zn > Cu > Pb > As > Cr > Ni > Sb. Considerable degree of enrichment was observed because the elements As, Cu, and Pb are at EF > 5 at locations 47, 53, 70, and 71. The values obtained from the Igeo, Cf, and PLI are a wide range of pollutants (from unpolluted to moderately polluted to extremely polluted to) for the various elements studied.     

Historical environmental pollution trend and ecological risk assessment of trace metals in marine sediments off Adyar estuary,Bay of Bengal,India

Geochemical, mineralogical and textural analyses were carried out in core sediments off Adyar estuary, Bay of Bengal, India to record the contamination trend from urban and industrial activities during the historical past. Quartz, feldspar, kaolinite, chlorite and illite were the main lithogenic and clay minerals; carbonate was the predominant biogenic mineral. Trace metals (Fe, Al, Cu, Cr, Ni, Pb and Zn) indicate more enrichment in the surface sediment layers due to recent anthropogenic activities. The mean anthropogenic factor (AF) values for trace metals in core sediments decreased in the following order: Cr > Ni > Zn > Cu > Pb. The pollution load index (PLI) values in Adyar core sediments ranged from 1 to 1.25 with an average of 1.07. Based on AF, PLI, and sediment quality guidelines values for trace metals, significant metal enrichment and ecological risk were obtained in upper-most sediment layer. Multivariate statistical methods such as correlation matrix, principal component analysis and cluster analysis were carried out to find the relationships among the texture size, metals and minerals. The pollution of Adyar estuarine sediments was started in the 1960s, responding to the rapid economic development in Chennai coastal and Adyar estuarine region in the last five decades. Despite these high concentrations in the upper layer, development and expansion of industries are still continuing. The stricter regulations for the discharge and remediation of sediments are urgent for the conservation of environments and human health.     

Spatio-temporal dynamics of heavy metals in sediments of the river estuarine system: Mahanadi basin (India)

Dynamics of heavy metals in the surface sediments of Mahanadi river estuarine system were studied for three different seasons. This study demonstrates that the relative abundance of these metals follows in the order of Fe > Mn > Zn > Pb > Cr > Ni ≥ Co > Cu > Cd. The spatial pattern of heavy metals supported by enrichment ratio data, suggests their anthropogenic sources possibly from various industrial wastes and municipal wastes as well as agricultural runoff. The metal concentrations in estuarine sediments are relatively higher than in the river due to adsorption/accumulation of metals on sediments during saline mixing, while there is a decreasing trend of heavy metal concentrations towards the marine side. The temporal variations for metals, such as Fe, Mn, Zn, Ni and Pb exhibit higher values during monsoon season, which are related to agricultural runoff. Higher elemental concentrations are observed during pre-monsoon season for these above metals (except Ni) at the polluted stations and for metals, such as Cr, Co and Cd at all sites, which demonstrate the intensity of anthropogenic contribution. R-mode factor analysis reveals that “Fe–Mn oxy hydroxide”, “organic matter”, “CaCO₃”, and “textural variables” factors are the major controlling geochemical factors for the enrichment of heavy metals in river estuarine sediment and their seasonal variations, though their intensities were different for different seasons. The relationships among the stations are highlighted by cluster analysis, represented in dendrograms to categorize different contributing sites for the enrichment of heavy metals in the river estuarine system.     

Potential ecological risk assessment of heavy metal contamination in sediment and water body around Dhaka export processing zone,Bangladesh

Sediments and surface water contamination by the industrial effluents containing heavy metals is the most detrimental environmental impact. Therefore, the present work attempts to determine the status of eight heavy metal distribution in sediments and water samples, and their ecological risks’ assessment in the studied area. The distribution pattern of heavy metals in the water and sediment follows the sequences: Zn > Cu > Pb > Cr > Mn > Ni > As > Cd and Mn > Zn > Cr > Pb > Cu > Ni > As > Cd, respectively. Gross water pollution is observed at different sampling points of Dhalai Beel and Bangshi River. The comparison of sedimentary mean metal concentrations with several environmental contamination monitoring parameters, viz, threshold effect level (TEL), probable effect level (PEL), and severe effect lever (SEL) indicates that the metal levels are less than PEL except Cr. Moreover, the level of contamination degree (C _d) and modified degree of contamination (mC _d) indicates ‘low’ and ‘nil to low’ degree of contamination, respectively. Pollution load indices (PLI) of the studied area are lower than unity, indicates no pollution. Furthermore, a toxic-response factor is applied to assess the potential ecological risk of these heavy metals into the water body. The results of this study exhibit a low potential ecological risk of heavy metals. The Pearson’s correlation and cluster analysis are also performed to assess the heavy metal interactions in water and sediment samples.     

Heavy metals pollution in the soils of suburban areas in big cities: a case study

Soil pollution in agricultural areas surrounding big cities is a major environmental problem. Tabriz is the largest city in the northwest of Iran and the fourth largest city in the country. Soil samples were taken from 46 sites in the suburbs of the Tabriz city, and separate samples were taken from control site and analyzed. The results indicated that the mean pH value of the soil samples was 9.29, while the mean EC value was 354.33 μs/cm and the amount of TOC and TOM was 0.99 and 1.7 %, respectively. The mean concentrations of Cd, Pb, Cu, Cr, Ni, and Zn in the soil were determined to be 1.61, 10.56, 101.25, 87.40, 38.73, and 98.27 mg/kg, respectively (dry weight). The concentrations of heavy metals (Cd, Pb, Cu, Cr, and Zn), with the exception of Ni, were higher than the concentrations of the same heavy metals at the control site. Despite these elevated concentrations, the concentrations of heavy metals were lower than the toxicity threshold limit of agricultural soils. The values of the pollution index revealed that the metal pollution level was Pb > Cr > Cu > Zn > Cd > Ni, and the mean value of the integrated pollution index was determined to be 1.81, indicating moderate pollution. Nevertheless, there were some sites that were severely polluted by Cr (maximum values of 1,364 mg/kg). It was concluded that city probably has affected the surrounding agricultural area. Application of wastewater (municipal and industrial) as irrigation water, using of sludge as soil fertilizer, and atmospheric perceptions have been considered as main reasons of increased heavy metals concentrations found in the studied area.     

Metal enrichment in the groundwater of the arid environment in South Africa

This paper presents the enrichment tendency and spatial distribution of metals in the groundwater which is pumped out from the granitic aquifers in South Africa. Groundwater is the sole source of water supply for the local community in the study area (Namaqualand), and hence, it was necessary to understand the controlling geochemical processes and interrelationship of metals in the groundwater. The geochemical association of metals has been assessed based on the geostatistical methods. The results show that geochemical processes such as oxidation, leaching, and evaporation besides water–rock interaction are very important in controlling metal enrichment in the groundwater from highly mineralized rocks. The metal enrichment index for selected toxic metals in groundwater increases in the order of Cd > U > Cr > Pb. The observed enrichment trend could be considered as a result of mineralization of basement rocks which is facilitated by active geochemical process in the arid environment. The lack of aquifer flushing due to negligible recharge helps the metals to concentrate at shallow groundwater zones supported by severe evaporation process.     

Assessment of heavy metal concentrations and associated resistant bacterial communities in bulk and rhizosphere soil of <Emphasis Type="Italic">Avicennia marina</Emphasis> of Pichavaram mangrove,India

Heavy metals are known to pose a potential threat to terrestrial and aquatic flora and fauna. Due to increasing human influence, heavy metal concentrations are rising in many mangrove ecosystems. Therefore, an assessment of heavy metal (Cd, Cr, Cu, Ni, Pb, Fe, Mn, and Zn) concentrations was conducted within the bulk soil and rhizosphere soil of Avicennia marina at the Pichavaram Mangrove Forest in India. The rhizosphere soil showed higher concentrations of metals than the bulk soil. Compared to the bulk soil, the metals Cd, Fe, Mn, and Zn were 6.0–16.7% higher, whereas Cr, Cu, Ni, and Pb were 1.7–2.8% higher concentration. Among the three selected sampling sites (dense mangrove forest, estuarine region, and sea region), the sea region had the highest concentration of all heavy metals except Zn. The trend of the mean metal concentration was Fe > Mn > Cr > Ni > Cu > Pb > Zn > Cd. Heavy metals concentrations elevated by the 2004 tsunami were persistent even after 4 years, due to sedimentary soil processes, the rhizosphere effect of mangroves, and anthropogenic deposition. Analysis of the heavy metal-resistant bacteria showed highest bacterial count for Cr-resistant bacteria and rhizosphere soil. The maximum level of heavy metal-resistant bacteria was observed at the site with the highest heavy metal contamination. The heavy metal-resistant bacteria can be used as indicator of heavy metal pollution and furthermore in bioremediation.     

Heavy metals in nearshore sediments of Kalpakkam,southeast coast of India

Kalpakkam, a tiny fishing hamlet dotting the east coast, halfway between Chennai and Pondicherry has become prominent due to the Madras Atomic Power Station. The present study aims at assessing the spatial and temporal distribution pattern of heavy metals (Cd, Pb, Zn, Cu, Ni, Cr, and Fe) from 12 stations along the inner shelf of Bay of Bengal, India, during pre-monsoon (PRM), monsoon, and post-monsoon (POM) seasons. The order of occurrence of the metals in sediments of Kalpakkam is Cr > Zn > Ni > Cu > Pb > Cd (excluding Fe since unit is in %) and exhibits a unique seasonal pattern with the highest values (average) during POM except for Cd which shows highest (average) concentration during PRM. In order to determine the sample association according to their geochemical composition and their granulometric characteristics, a correlation matrix was generated and sediment pollution indices viz., sediment enrichment factor and geoaccumulation index were computed. The results confirm anthropogenic input of Cd to nearshore sediments of Kalpakkam. Sources of Cd can be attributed to dredging activities at Edaiyur, direct dumping and sewage sludge from anthropogenic activities, which reach the study area through the Buckingham Canal opening at the backwaters—Sadras and Edaiyur, and extreme use of antifouling paints by fishing trawlers.     

A study on soil physico-chemical, microbial and metal content in Sukinda chromite mine of Odisha, India

Soil samples from chromite mining site and its adjacent overburden dumps and fallow land of Sukinda, Odisha, were analysed for their physico-chemical, microbial and metal contents. Chromite mine soils were heterogenous mixture of clay, mud, minerals and rocks. The pH of the soils ranges between 5.87 and 7.36. The nutrient contents of the mine soils (N, P, K and organic C) were found to be extremely low. Analysis of chromite mine soils revealed accumulation of a number of metals in high concentrations (Fe > Cr > Mn > Ni > Zn > Pb > Sr) which exceeded ecotoxicological limits in soil. Correlation and cluster analysis of metals revealed a strong relation between Cr, Ni, Fe, Mn among the different attributes studied. Assessment of different microbial groups such as fungi, actinomycetes and bacteria (heterotrophic, spore forming, free-living nitrogen fixing, phosphate solubilising and cellulose degrading) from mine soils were found to be either extremely low or absent in some soil samples. Further chromium tolerant bacteria (CTB) were isolated using 100 mg/L Cr(VI) enriched nutrient agar medium and were screened for their tolerance towards increasing concentrations of hexavalent chromium and other toxic metals. Out of 23 CTB isolates, three bacteria tolerated up to 900 mg/L, 6 up to 500 mg/L, 20 up to 200 mg/L of Cr(VI). These bacteria were also found to be sensitive towards Cu > Co > Cd and very few CTB strains could show multiple metal tolerance. These strains have great scope for their application in bioremediation of toxic chromium ions in presence of other metals ions, which needs to be explored for their biotechnological applications.     

Heavy metal content in the beach sediment with respect to contamination levels and sediment quality guidelines: a study at Kalpakkam coast,southeast coast of India

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.     

Contamination assessment and health risk of heavy metals in dust from Changqing industrial park of Baoji,NW China

The contents of Co, Cr, Cu, Mn, Ni, Pb and Zn in the dust samples collected from Changqing industrial park of Baoji city, NW China, were measured by XRF, while As and Hg in the dust samples were analyzed by AFS. Geo-accumulation index (I _geo), pollution index (PI) and integrated pollution index (IPI) were calculated to evaluate the heavy metal contamination level of dust. The health risk due to exposure to heavy metals in dust was analyzed by the Health Risk Assessment Model of US EPA. The results show that the arithmetic means of As, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn are 23.3, 16.4, 1591.8, 178.2, 0.243, 346.5, 40.2, 1,586.2 and 1,918.8 mg kg^?1, respectively, which are higher than the background values of Shaanxi soil, especially for Cr, Cu, Hg, Pb, and Zn. The mean values of I _geo reveal the order of Pb > Zn > Cr > Hg > Cu > As > Co > Ni > Mn. The high I _geo of Cr, Cu, Hg, Pb and Zn in dust indicates that there is considerable pollution from Cr, Cu, Hg, Pb and Zn, while the low I _geo of As, Co, Mn and Ni presents no pollution in dust. The assessment results of PI support the results of I _geo, and IPI indicates heavy metals in dust polluted seriously. The health risk assessment shows that ingestion of dust particles is the route for exposure to heavy metals from dust, followed by dermal adsorption. Exposure to As, Cr and Pb from dust may pose a potential health threat to children and adults. The risk of cancer from As, Co, Cr and Ni due to dust exposure is low.