Heavy metals,polycyclic aromatic hydrocarbons and organochlorine pesticides in the surface sediments of mangrove swamps from coastal sites along the Leizhou Peninsula,South China

Contents of heavy metals, polycyclic aromatic hydrocarbons （PA Hs）, dichlorodiphenyltrichloroethanes （DDTs） and hexachlorcy- clohexanes （HCHs） in surface sediments from mangrove areas of the Leizhou Peninsula were analyzed in July and November 2005. Risk assessment criteria applied by Long E R et al. （1995） and Long E D et al. （1995） （effects range low, ERL; effects range mean, ERM） of chemicals in sediments from the gulf or estuary were used to assess the potential ecological risks of heavy metals, PAHs, DDTs and HCHs to aquatic organisms in the studied area. The results indicated that the average contents of zinc, nickel, chromium, lead, copper, arsenic and mercury were （61.97 ± 55.87）, （59.99 ± 39.01 ）, （47.93 ± 28.37）, （26.64± 13.00） , （23.45 ± 41.96）, （9.32 ± 3.62）, （0.14 ± 0.18） mg/kg in dry weight in the sediment samples col- lected from five studied sites in the Leizhou Peninsula, respectively. Cadmium was not calculated due to its content being below the detection limit （ 〈 0.3 mg,/kg）. The average levels of Cr, Cu, Ni, Pb, Zn and Hg exceed their background values. The average contents of Ni were higher than ERM. The contents of PAHs in the sediments from the five studied sites were （79.78 ± 43.70） ng/g in dry weight, far lower than ERL（4 022 ng/g）. The contents of DDE, DDD and DDTs in the sediments from five studied sites were （2.60 ± 4.68）, （ 17.52 ± 27.25 ）, （27.78 ± 46.64） ng/g in dry weight respectively, clearly higher than ERL, and the average contents of DDT were （7.66 ± 15.93） ng/g in dry weight, much higher than ERM. HCHs could be detected in the sediments only from Gaoqiao sampling site, with the average contents （0.07 ± 0.08） ng/g in dry weight.

Vertical Distribution and Pollution Assessment of Heavy Metals in Mangrove Sediments of Dongzhai Harbor, Hainan

This study was conducted to reveal the vertical distribution and concentration variation of heavy metals（Cr, Co, Ni, Cu, Zn, As, Cd and Pb） in the mangrove sediments of Dongzhai Harbor, Hainan by using inductively-coupled plasma mass spectrometry（ICP-MS）. The surface sediment samples were collected from 15 sites, and a geoaccumulation index（Igeo） was estimated to quantify the pollution status of the mangrove sediments. The results showed that the concentrations of heavy metals in sediments followed the order of Cr〉 Zn〉 Ni〉 Cu 〉Pb 〉Co〉 Cd. A common pattern was found in some heavy metals（Cu, Zn, As and Pb） as their concentrations were significantly and negatively correlated with depth. Cr concentration in upper layer was slightly lower than that in middle and lower layers,while the concentrations of Ni and Cd in middle layer were slightly higher than in upper and lower layers. The geoaccumulation index indicated that the surface sediments at sites QT-1-01, QT-1-02, QT-2, GN-1, GN-2 and GN-3 were strongly polluted by Cd, and unpolluted to moderately polluted or moderately polluted by As.

Distribution Pattern of Heavy Metals in the Surface Sediments of the Jiaozhou Bay

Grain size analysis and chemical analysis of heavy metals are made for 312 surface samples of the Jiaozhou Bay. Nineteen samples of the waste water taken from the sewage discharge outlets along the eastern coast of the bay are also analyzed for heavy metals. Results show that heavy metals are richer in the east and poorer in the west of the bay. Sedimentary dynamic studies reveal that the distribution of heavy metals in the surface sediments of the Jiaozhou Bay is under the control of hydrodynamics.

Correlations between Geo-Chemical Speciation of Heavy Metals (Cu, Zn, Pb, Cd and Ni) in Surface Sediments and Their Concentrations in Giant Mudskipper (Periophthalmodon schlosseri) Collected from the West Coast of Peninsular Malaysia

Surface sediments and giant mudskipper (Periophthalmodon schlosseri) were collected in August and September 2008 and in March and June 2010 from six sampling sites in the west coast of Peninsular Malaysia to assess heavy metals accumulation in the giant mudskipper. Sequential extraction technique was used to fractionate the sediments into four different geo-chemical fractions;easily, freely or leachable and exchangeable (EFLE), acid reducible, oxidizable organic and resistant fractions. Heavy metals concentrations (Cu, Zn, Pb, Cd and Ni) in the surface sediments and giant mudskipper were determined by using air acetylene flame atomic absorption spectrophotometer (AAS) Perkin Elmer Analyst 800. The results of Pearson’s correlation analyses showed that metal concentrations in the tissues of P. schlosseri were significantly correlated (p p < 0.05), correlations were observed between Cu in P. schlosseri and Cu in the sediment (oxidisable-organic, resistant and total Cu), Zn in P. schlosseri and Zn in the sediment (EFLE and total Zn), Pb in P. schlosseri and Pb in the sediment (with all the four fractions of Pb), Cd and Ni in P. schlosseri and Cd and Ni in the sediment (with all fractions of Cd and Ni except acid-reducible Cd and Ni) which might suggest the use of P. schlosseri as a biomonitoring agent for heavy metals pollution in the west coast of Peninsular Malaysia.

Heavy Metal Distribution in Sediments of Muthupettai Mangroves, South East Coast of India

Core sediments from the Muthupettai mangroves on the southeast coast of India were analyzed for soil texture,total nitrogen,organic carbon,phosphorus and heavy metals(Fe,Mn,Cr,Cu,Ni,Pb,Zn and Cd).The distinct seasonal variation in the distribution of metals in the sediments was observed.The minimum concentration was recorded in river mouth and the maximum was in lagoon.High metal concentration in sediment was observed during monsoon and low concentration in summer.The total nu-trient in lagoon and river mouth was recorded in the range of 4.528 to 8.526 mg g-1 for organic carbon,2.213 to 10.5 mg g-1 for nitro-gen and 0.824 to 7.22 mg g-1.

Distribution and Accumulation Characteristics of Heavy Metals in Sediments in Southern Sea Area of Huludao City, China

The southern sea area of the Huludao City, Liaoning Province might be polluted by heavy metals because it is close to the Jinzhou Bay, one of the heaviest sea area polluted by heavy metals in China. The undisturbed modem sediment core can be used to analyze the accumulation and source of the pollutants using 137Cs and 21pbex. Thirty-five samples of surface sediment and two core sedi- ments were collected from the southern sea area of Huludao City. The concentrations of copper （Cu）, lead （Pb）, chrome （Cr）, zinc （Zn）, arsenic （As） and mercury （Hg） in the surface sediments as well as Cu, Pb, Zn, Cr, 137Cs and 2~~pbex in the core sediments were deter- mined to research the spatial distribution and accumulation characteristics, and to analyze the sources and the potential risks of heavy metals. The results show that the pollution levels of Zn and Hg are serious, and 26 stations are at moderate or heavy ecological risks. The concentrations of the heavy metals increase from east to west, as well as from open sea to offshore marine area. The concentrations of heavy metals are not high in the sediments adjacent to the Jinzhou Bay, and the influence caused by the seawater exchange with the Jinzhou Bay is little. The concentrations of the heavy metals in the core sediments show low-high-low characteristic, and it coincides with the pollution history of Huludao City. The atmospheric deposition of heavy metals from the Huludao Zinc Plant is likely to be the main source of pollution without direct discharge of wastewater. The high concentrations of heavy metals appear on the upper sediment of 20 cm. The shallow sediment with high heavy metal contents might be exposed to surface when it was disturbed by the ocean engineering and big storm surge, then cause risk to the safety of aouaculture and human honlthy.

Spatial Distribution and Ecological Risk Assessment of Heavy Metals in Surface Sediment of Songhua River,Northeast China

The Songhua River,one of the seven major rivers in China,locates in Northeast China with 1897 km long.This study aims to investigate the concentrations,distribution,source apportionment and ecological risk assessment of heavy metals including copper(Cu),zinc(Zn),cadmium(Cd),lead(Pb),nickel(Ni)and chromium(Cr)in main stream and tributaries of the Songhua River in Jilin Province,Northeast China.Surface sediment samples(0–15 cm)were collected from 39 sampling sites in the Songhua River in July 2012.Concentrations of Cu,Zn,Cd,Pb,Ni and Cr were analyzed.The mean concentrations of heavy metals were(24.0±9.2)mg/kg,(59.3±18.0)mg/kg,(4.0±2.1)mg/kg,(39.0±27.9)mg/kg,(18.5±8.6)mg/kg and(56.1±17.6)mg/kg for Cu,Zn,Cd,Pb,Cr and Ni,respectively.The average contents of Cu,Cd,Pb,Cr and Ni were higher than their background values.Higher concentrations of heavy metals were found in the lower reaches with industrial enterprises and cities along the Songhua River.Zn,Pb and Ni might come from industrial sewage and mineral processing,while Cu and Cd were derived from electroplating wastewater and agricultural non-point source sewage.Cr originated from lithogenic sources.The concentrations of Cu,Zn and Cr were below the effect range low(ERL)at all sites,while Cd,Pb and Ni concentrations were detected ranging from ERL to the effect range median(ERM)at more than 15%of samples.Concentrations of Ni exceeded ERM in more than 50%of samples.The mean toxic units of heavy metals in the Songhua River decreased following the order:Cd(6.7)>Pb(2.2)>Ni(1.6)>Cu(0.7)>Cr(0.5)=Zn(0.5).Potential ecological risk index was found to be higher in middle and lower reaches of the Songhua River,where Cd could impose an extremely high ecological risk.

Speciation and potential remobilization of heavy metals in sediments of the Taihu Lake, China

The species of Cu, Pb, Zn, Cd and Cr in sediments of the Taihu Lake, China, have been analyzed using the sequential chemical extraction method. Variations in the chemical fractions of these metals and their geographic distributions have also been studied. For all five metals, the residual fraction is highest but the exchangeable fraction is lowest among all the fractions. Compared to other metals, Cd has the highest percentage in the exchangeable fraction, and Cr is associated mainly with the residual fraction. Cu in the organic fraction and Pb in the Fe-Mn fraction are the important species, whereas the lowest percentages are found for Cd in the organic fraction, Cu in the Fe-Mn oxide fraction and Pb in the carbonate fraction. With respect to spatial differences, the total contents in the non-residual fractions of the metals in bay sediments are found to be higher than those in other sediments. The fractions of Cd, Cu and Cr showed significant variations in different regions. The fractions of Pb and Zn, however, did not show significant variations in spatial distribution, suggesting different amounts and different paths of anthropogenic input for the metals. Comparisons of the metal speciation indicated that Cd might be the most bioavailable metal, followed by Pb.

HEAVY METAL POLLUTION IN SURFACE SEDIMENTS COLLECTED FROM DRAINAGES RECEIVING DIFFERENT ANTHROPOGENIC SOURCES FROM PENINSULAR MALAYSIA

Surface drainage sediments were collected, between January and April in 2005, from 6 sampling sites in Peninsular Malaysia suspected to have received different anthropogenic sources. These drainages included sites near a petrochemical plant, an electronic factory, a metal factory and 2 townships in addition to a relatively unpolluted site (a reference site). Based on the aqua-regia method, the metal concentrations for all the sampling sites except for the agricultural site (reference site) at Sg. Benut were between 60.92-1 019 μg/g dry weight for copper (Cu), 65.32-1 266.6μg/g dry weight for plumbum (Pb), 1.46-15.93 μg/g dry weight for cadmium (Cd), 330.10-484.14 μg/g dry weight for zinc (Zn) and 47.03-120.90 μg/g dry weight for nickel (Ni). All of these ranges were significantly (p< 0.05) higher than those (Cu: 8.77 μg/g; Pb: 57.42 μg/g; Cd: 0.96 μg/g; Zn: 68.21 μg/g; and Ni: 17.87 μg/g) of the reference site at Sg. Benut that only received agricultural disposal. The concentrations for the 5 metals from all the sites (except for the reference site) were higher than the Sediment Quality Values for Hong Kong by Chapman et al (1999) for the 5 metals. Based on the sequential extraction technique, 3 geochemical fractions [easily, freely leachable and exchangeable (EFLE), acid-reducible and oxidisable-organic] were also useful in identifying these polluted sites. The elevated metal concentrations found in the sediments might be related to point sources of industrial effluent and urban waste. Hence, the results emphasized the necessity for the treatment of effluents into this drainage area. As part of the effort to control illegal discharges and dumping into drainages, public awareness should be enhanced.

Distribution of Heavy Metals in the Sediments in Polluted Coastal Regions of China and Their Ecological Risks

[ Objective] The aim was to study the distribution and its ecological risks of heavy metal in the sediments of the polluted coastal regions in Bohai Bay, Changjiang and Zhujiang estuaries. [Method] The economic activities had great influence on the Bohai Bay, Changjiang and Zhu- jiang estuaries. The pollution of different heavy metals in the deep ocean was summarized by summary of the relation between the distribution of heavy metals and economic activities. [ Result] In general, influenced by economic development, the heavy metal pollution in coastal area in China was pessimistic. The sediments in the Bohai Bay, Changjiang and Zhujiang estuaries showed different degrees of Cd, Cr, Zn, Cu and Pb pollution. As pollution in Bohal Bay and Zhujiang estuaries can not be neglected. The heavy metal pollution may pass into human body with the transportation of food chain. [ Conclusionl The study provided reference for the formulation of policies to restrain heavy metal emission and protection of human health.

Distribution and relationship between antimicrobial resistance genes and heavy metals in surface sediments of Taihu Lake,China

Heavy metals, pharmaceuticals, and other wastes released into the environment can significantly influence environmental antibiotic resistance. We investigated the occurrence of 22 antimicrobial resistance genes(ARGs) and 10 heavy metal concentrations, and the relationship between ARGs and heavy metals in surface sediment from seven sites of Lake Taihu. The results showed significant correlations(p < 0.05) between sediment ARG levels,especially for tetracycline and sulfonamides(e.g., tet(A), tet(D), tet(E), tet(O), sul1, sul2 and int-1) and specific heavy metals(Fe, Mn, Cr, Cu, Zn, among others) in the Lake. In the surface sediments, heavy metals showed an interaction with resistance genes, but the strength of interaction was diminished with increasing depth. For most of the heavy metals, the concentration of elements in the top sediments was higher than that in other depths.Tetracycline resistance genes(tet(A), tet(B), tet(D), tet(E) and tet(O), β-lactam resistance genes(SHV, TEM, CTX, OXA and OXY) and sulfonamide resistance genes(sulA, sul1, sul2, sul3 and int-1) were detected. They showed a trend which inferred a statistically significant increase followed by decreases in the relative abundance of these ARGs(normalized to 16 S rRNA genes) with increasing depth. This study revealed that tet(A), tet(O), TEM, OXY, int-1, sul1 and sul3 were widespread in surface sediments with high abundance, indicating that these genes deserve more attention in future work.

Assessment of heavy metal levels in surface sediments of estuaries and adjacent coastal areas in China

This article investigates the variations of contamination levels of heavy metals such as copper, lead, chromium, cadmium, zinc, arsenic, and mercury over time in surface sediments of the Changjiang River Estuary （CRE）, Yellow River Estuary （YRE）, Pearl River Estuary （PRE）, and their adjacent coastal areas in China. The contamination factor （CF）, pollution load index （PLI）, and geoaccumulation index （Igeo） are used to evaluate the quality of the surface sediments in the study areas. The results showed that the CRE, YRE, and their adjacent coastal areas were at a low risk of contamination in terms of heavy metals, while the PRE and its adjacent coastal area were at a moderate level. By comparison, the concentrations of heavy metals in the surface sediments of the YRE and its adjacent coastal area were relatively lower than those in the CRE, PRE, and their adjacent coastal areas.

Concentrations of Cu, Pb, Zn, Cr and Cd in Surficial Sediments from Mangrove Wetlands of China

Mangrove sediments were sampled form 14 main mangrove reserves of China. Concentrations of Cu, Pb, Zn, Cr and Cd were analyzed with a PE ICP-MS, and physical and physicochemical factors such as particle size distribution, pH, salinity and Total Organic Matter （TOM） were also determined. In the mangrove sediments of China, the average contents of heavy metals decreased in the order ofZn 〉 Pb 〉 Cu 〉 Cr 〉 Cd. The average contents of heavy metals were： Cu = 22.8 4- 16.46 mg/kg, Pb = 76.1 4- 52.33 mg/kg, Zn = 86.3 4- 42.65 mg/kg, Cr = 18.4 4- 5.83 mg/kg and Cd = 0.21 4- 0.25 mg/kg. Compared with previous studies, levels of heavy metals increased greatly. Contents of Cd, Cu, Pb and Zn were higher than the Background Values （BV）. However, the contents of Cr was under the BV. The results revealed that levels of heavy metals changes significantly with anthropogenic input, physical and physicochemical factors. Significant correlations were found between concentrations of Cu, Ph and pH, TOM.

Content and Ecological Risk Assessment of Heavy Metals in Surface Sediment in Weishan Lake

[Objective] The aim was to analyze the content of heavy metals in surface sediment in Weishan Lake and further assess its ecological risk.[Method] Heavy metal pollution in surface sediment in Weishan Lake was studied,and the pollution indices and potential ecological risk indices of Cu,Zn,Pb,Cd and Cr were calculated to assess the potential ecological risk of heavy metal pollution.[Result] In surface sediment in Weishan Lake,the average contents of Cu,Zn,Pb,Cd,Cr and Ni were 64.78,185.05,78.76,0.17,37.76 and 46.84mg/kg respectively.Cr and Cd weren’t beyond standards in all stations,while Cu and Pb exceeded standards in all stations,with average super-standard multiple of 0.85 and 0.31,respectively,and Zn content wasn’t beyond standard in S2 station,with average super-standard multiple of 0.24.The average pollution indices of Cu,Zn,Pb,Cd and Cr were 1.85,1.23,1.31,0.34 and 0.47 respectively,with average comprehensive pollution index of 5.21,which showed that heavy metal pollution was light.In addition,heavy metal pollution in entryway portion and sea-route portion were more serious than that of breeding portion.Potential ecological risk assessment showed that the average potential ecological risk indices of Cu,Zn,Pb,Cd and Cr were 9.25,1.23,6.56,10.34 and 0.94 respectively,with average comprehensive potential ecological risk index of 28.33,and it revealed that potential ecological risk of heavy metals was slight.Besides,the potential ecological risk order of heavy metal pollution was sea-route portion>entryway portion>breeding portion.[Conclusion] The study could provide references for the regulation and improvement of ecological environment in Weishan Lake in the east route of south-to-north water transfer project.

Concentrations and contamination trends of heavy metals in the sediment cores of Taihu Lake,East China,and their relationship with historical eutrophication

To assess the contamination trends and potential bio-availability of sediment-bound heavy metals,concentrations of heavy metals in acid-leaching fraction and in bulk sediments from the two typical bays(the Meiliang Bay and Xuhu Bay) of the Taihu Lake,East China,were studied.Pb and Zn showed elevated concentrations in the sediments from both areas,although sedimentation history and degree of pollution are different between the two bays.In the Meiliang Bay,both Pb and Zn pollutions started in the late 1970's,the same time as the beginning of eutrophication of the lake,while the in the Xuhu Bay the metal contamination started since recent 10 years.The concentrations of acid-leachable Pb in the sediments from the Meiliang Bay are correlated with the historical eutrophication process.Before the eutrophication and heavy metal pollution,the chemical properties of the lake sediments were the same as the source compositions of the Xiashu loess.Both Pb and Zn in the sediments mainly occur in leachable forms by nitric or hydrochloric acid,whilst most of Cu is in residual fraction.The results indicate that both Pb and Zn may have higher mobility and bioavailability in water and biology than Cu.

Source analysis and risk evaluation of heavy metal in the river sediment of polymetallic mining area:Taking the Tonglüshan skarn type Cu-Fe-Au deposit as an example,Hubei section of the Yangtze River Basin,China

In this paper,25 sampling points of overlying deposits in Tonglushan mining area,Daye City,Hubei Province,China were tested for heavy metal content to explore pollution characteristics,pollution sources and ecological risks of heavy metals in sediments.A geo-accumulation index method was used to evaluate the degree of heavy metal pollution in the sediment.The mean sediment quality guideline quotient was used for evaluating the ecological risk level of heavy metal in the sediment.And a method of correlation analysis,clustering analysis,and principal component analysis was used for preliminary analysis on the source of heavy metal in the sediment.It was indicated that there was extremely heavy metal pollution in the sediment,among which Cd was extremely polluted,Cu strongly contaminated,Zn,As,and Hg moderately contaminated,and Pb,Cr,and Ni were slightly contaminated.It was also indicated by the mean sediment quality guideline-quotient result that there was a high ecological risk of heavy metals in the sediment,and 64%of the sample sites had extremely high hidden biotoxic effects.For distribution,the contamination of branches was worse than that of the main channel of Daye Dagang,and the deposition of each heavy metal was mainly influenced by the distance from this sample site to the sewage draining exit of a tailings pond.The source analysis showed that the heavy metals in the sediment come from pollution discharging of mining and beneficiation companies,tailings ponds,smelting companies,and transport vehicles.In the study area,due to the influence of heavy metal discharging from these sources,the ecotoxicity of heavy metals in the sediment was extremely high,and Cd was the most toxic pollutant.The research figured out the key restoration area and elements for ecological restoration in the sediment of the Tonglüshan mining area,which could be referenced by monitoring and governance of heavy metal pollution in the sediment of the polymetallic mining area.

Spatial Distribution and Anthropogenic Assessment of Heavy Metals in the Surface Sediments of Klang River

The study was conducted to quantify the concentration and distribution of metals (Cd, Zn, Ni, Cu, Pb, and Fe) in the surface sediments and to assess the status of metal contaminations in the Klang River, Malaysia. The concentrations of metals (μg∕g, Fe%, dry weight) were as follows: 0.57-2.19 μg∕g Cd; 31.89-272.33 μg∕g Zn; 5.96-24.47 μg∕g Ni; 10.57-52.87 μg∕g Cu; 24.23-64.11 μg∕g Pb and 1.56%-3.03% Fe. Sequential extraction technique (SET) showed that mean anthropogenic portions of metals were in the order of Zn (60.22%), Cu (56.01%), Cd (45.63%), Ni (42.08%), Pb (33.22%) and Fe (10.26%). The highest concentrations of metals ( p<0.05) were found in the stations located close to industrial parks and highly populated areas. The results of the present study showed that the effectiveness of total organic carbon (TOC) contents in controlling the distribution and enrichment of metals was a more important factor compared to grain size. The study also indicated that the control of metals pollution from direct influx of domestic wastes and insufficiently treated industrial wastes in the Klang River was an important and desirable way to minimize the detrimental effects of metals.

Ecological Risk of Heavy Metals in Sediment Around Techeng Island Special Marine Reserves in Zhanjiang Bay

The concentrations of five metals(Cu, Pb, Zn, Cd and Hg) were measured in sediments obtained before and after the establishment of Techeng Island Special Marine Reserves(TCISMR) in Zhanjiang Bay to evaluate the ecological risk of heavy metals. The results showed that average values of potential ecological risk indexes of heavy metals at all stations increased slightly from 32.09 to 30.54 after establishment of TCISMR. Optimal semivariance simulation showed that the contents of five heavy metals have strong spatial correlations in August 2010(before), while this correlations weakened in April 2013(after establishment of TCISMR), suggesting that the main sources of heavy metals changed. The Hakanson Risk Index(HRI) values in Donghai levee, central and southern parts of Zhanjiang harbor were high up to 60.13 and 46.46, respectively. And Zhanjiang Bay Channel, the areas around special marine reserves, the artificial reef areas and mangrove areas at south of Techeng Island are the areas with low ecological risk and high ecological value, which should be treated as the prior ecological protection areas. Our study provided a priority control pattern of heavy metal pollution in TCISMR, which greatly benefits the sustainable development and resource protection in Zhanjiang Bay.

Distribution and assessment of heavy metals in the surface sediment of Yellow River, China

Large amounts of heavy metals discharged by industrial cities that are located along the middle reach of Yellow River, China have detrimental impacts on both the ecological environment and human health. In this study, fourteen surface sediment samples were taken in the middle reach of the Yellow River. Contents of Zn, Pb, Ni, Cu, Cr, Cd, As were measured, and the pollution status was assessed using three widely used pollution assessment methods, including the single factor index method, Nemerow pollution index method and potential ecological risk index. The concentrations of the studied heavy metals followed the order： Zn 〉 Cr 〉 Cu 〉 Ni 〉 Pb 〉 As 〉 Cd. Nearly 50% of sites had Cu and Cr accumulation. The concentration of Cu at the Yiluo River exceeded the secondary standard value of the Environmental quality standard for soils. Comparison of heavy metal concentrations between this study and other selected rivers indicated that Cu and Cr may be the major pollutants in our case. The single factor index indicated that many samples were at high levels of pollution for Cu and Cd; the Nemerow pollution index indicated that the Yihe River, Luohe River, Yiluo River and Huayuankou were polluted. According to the results of potential ecological risk assessment, Cd in the tributaries of Luo River, Yihe River,and Yiluo River showed high risk toward the ecosystem and human health, Cd in Huanyuankou and Cu in Yiluo River showed a middle level of risk and other samples were at a low level of risk.