Spatial distribution and potential ecological and health risks associated with heavy metals in the Ijero-Ekiti mining site,Nigeria

Artisanal gold mining,a labor-intensive and antiquated technique,is a growing industry and the source of income for rural communities all over the world.However,artisanal gold mining has potential negative and long-term effects on economy,environment,and society.This study collected soil samples from 16 sample points including a control point to examine the pollution degrees and spatial distribution of heavy metals,as well as ecological and health risks associated with heavy metal pollution in the Ijero-Ekiti mining site,Nigeria.Geographical Information System(GIS)and remote sensing technologies were used to identify regions with high concentrations of heavy metals and assess the environmental impact of gold mining activities.The results show that the mean heavy metal concentrations of 16 soil pointa are 8.94(±5.97)mg/kg for As,0.18(±0.54)mg/kg for Cd,0.11(±1.06)mg/kg for Co,14.32(±3.43)mg/kg for Cr,6.89(±0.64)mg/kg for Cu,48.92(±11.77)mg/kg for Fe,135.81(±30.75)mg/kg for Mn,5.92(±0.96)mg/kg for Ni,5.72(±1.66)mg/kg for Pb,and 13.94(±1.38)mg/kg for Zn.The study reveals that heavy metal concentration in soils follows the order of Mn>Fe>Cr>Zn>As>Cu>Ni>Pb>Co>Cd.An analysis of soil samples indicates that 3 principal components(PCs)account for 70.008%of the total variance and there are strong positive correlations between various pairs of heavy metals.The total potential ecological risk index(309.599)in the study area is high.Non-carcinogenic risk suggests that there may be long-term health impacts on people who work in the mining areas due to chronic exposure to the environment.Based on the study,the hazard index of carcinogenic health risks associated with heavy metals through ingestion is 520.00×10^(–4).Dermal contact from As and Cr also increases the risk of cancer,with the highest hazard index value of 18.40×10^(–4).The lowest exposure pathway,with the hazard index value of 0.68×10^(–4),indicates that the inhalation of heavy metals has a comparatively low risk of cancer.This study recommends the formulation of policies to monitor the Ijero-Ekiti mining site and other regions in Nigeria where indiscriminate artisanal gold mining activities exist.

Spatio-temporal Evolution and Optimization of Landscape Ecological Risk in Karst Mountainous Areas

[Objective]The ecological vulnerability and landscape ecological risk of karst mountainous areas have increased as a result of enhanced disturbance of natural resources by human activities.This paper aimed to explore the characteristics of ecological risk evolution under different landscape patterns in the region,with a view to providing reference for land classification protection,sustainable use of resources and regional ecological risk optimization in karst mountainous areas.[Method]Taking Huangping County,a typical karst mountainous area,as an example,eight evaluation factors of natural and landscape patterns were selected to construct a landscape ecological risk evaluation model,to quantitatively explore the spatio-temporal evolution of landscape ecological risk and the trend of risk level transfer in the study area from^(2)010-2018,and to reveal the complex relationship between ecological risk and topography in karst mountainous areas.[Result]①From 2010 to 2018,land use types changed to different degrees,with the most amount of woodland transferred out(1627.37 hm^(2))and the most amount of construction land transferred in(1303.93 hm^(2));a total of 3552.31 hm^(2) of land was transferred,with a change ratio of 2.13%,and there was a significant conversion between construction land,arable land,and woodland.②From 2010 to 2018,the landscape ecological risk in the study area changed significantly,and the landscape ecological risk index decreased from 0.3441 to 0.1733,showing an upward and then downward trend;the landscape ecological risk of the whole region was dominated by low-risk and lower-risk zones,and the ecological risk level generally shifted from a high level to a low level,and the ecological environment was improved.③There was a negative correlation between ecological risk and topographic position,and high-risk zones were mainly distributed among low topographic zones;with the change of time,the advantage of risk level for the selection of topography was gradually weakened,and the influence of anthropogenic factors on the ecological risk of the landscape was becoming more and more prominent.[Conclusion]This paper can provide theoretical basis for land use optimization and ecological protection in karst mountainous areas.

Ecological risk assessment of heavy metals in sediments of Xiawan Port based on modified potential ecological risk index

Modified potential ecological risk index （MRI） was proposed based on the potential ecological risk index （RI） and risk assessment code （RAC） by modifying an index. The modified index was relevant to the chemical speciation of heavy metals. Xiawan Port, a typical region contaminated by industrial production, was selected as a case study area. The total concentrations and chemical speciation of heavy metals in sediments of Xiawan Port were analyzed. The experimental data indicate that Xiawan Port is seriously polluted by heavy metals, especially by Cd. The risks of heavy metals are evaluated by RI, RAC and MRI, respectively. The resluts of MRI show that the risks of heavy metals are in the decreasing order of Cd〉Pb〉Cu〉Zn. Comparison of results by different methods reveals that MRI integrates the characters of RI and RAC. MRI is recognized to be useful for risk managemnt of heavy metals in sediments.

Spatial distribution and ecological risk of heavy metals and their source apportionment in soils from a typical mining area, Inner Mongolia, China

Determining the distributions and sources of heavy metals in soils and assessing ecological risks are fundamental tasks in the control and management of pollution in mining areas.In this study,we selected 244 sampling sites around a typical lead(Pb)and zinc(Zn)mining area in eastern Inner Mongolia Autonomous Region of China and measured the content of six heavy metals,including cuprum(Cu),Zn,Pb,arsenic(As),cadmium(Cd),and chromium(Cr).The ecological risk of heavy metals was comprehensively evaluated using the Geo-accumulation index,Nemerow general pollution index,and potential ecological risk index.The heavy metals were traced using correlation analysis and principal component analysis.The results showed that the highest content of heavy metals was found in 0–5 cm soil layer in the study area.The average content of Zn,As,Pb,Cu,Cr,and Cd was 670,424,235,162,94,and 4 mg/kg,respectively,all exceeding the risk screening value of agricultural soil in China.The areas with high content of soil heavy metals were mainly distributed near the tailings pond.The study area was affected by a combination of multiple heavy metals,with Cd and As reaching severe pollution levels.The three pathways of exposure for carcinogenic and noncarcinogenic risks were ranked as inhalation>oral ingestion>dermal absorption.The heavy metals in the study area posed certain hazards to human health.Specifically,oral ingestion of these heavy metals carried carcinogenic risks for both children and adults,as well as noncarcinogenic risks for children.There were differences in the sources of different heavy metals.The tailings pond had a large impact on the accumulation of Cd,Zn,and Pb.The source of Cr was the soil parent material,the source of As was mainly the soil matrix,and the source of Cu was mainly the nearby Cu ore.The purpose of this study is to more accurately understand the extent,scope,and source of heavy metals pollution near a typical mining area,providing effective help to solve the problem of heavy metals pollution.

Contamination and Ecological Risk Assessment of Heavy Metal in the Sediment of Turag River, Bangladesh: An Index Analysis Approach

Encroachment, disposal of untreated domestic and industrial wastewater and dumping of solid wastes have degraded the overall quality of the river Turag, which is located in Dhaka—the Capital City of Bangladesh. The present study investigated the extent of pollution of sediments of this river and analyzed the regional variability for the concentrations of Cr, Pb, Zn, Cu and Cd—all of concern because of their potential toxicity, using atomic absorption spectrophotometer. As per US EPA sediment quality guideline, metal concentrations ranged between Cd: 0.00 - 0.80, Cr: 32.00 - 75.50, Cu: 46.30 - 60.00, Pb: 28.30 - 36.40, and Zn: 94.60 - 190.10 mg/kg in the Turag river sediments. Cr, Cu, Zn belongs to moderately to highly polluted, Pb and Cd belongs to not polluted for Turag river. The heavy metals contamination in the sediments were also evaluated by applying Index of geo-accumulation (Igeo), contamination factor (Cf), pollution load index (PLI) etc. Toxicity characteristics leaching procedure (TCLP) test (US EPA 1311) for sediment samples have been performed also for metals (Pb, Cd, Cr, Cu and Zn) to determine the readily toxicity level of heavy metals. Sieve analysis of sediment performed in this study to determine the physical characteristic of sediment samples. The metal concentrations are well below the regulated level as per US EPA. This index can be complemented with the contamination index, which allows more site-specific and accurate information on contaminant levels. If the aim of work on contamination evaluation is to assess the overall contamination of a study area, the indices are highly appropriate.

Environmental availability and ecological risk assessment of heavy metals in zinc leaching residue

Four different methods,namely mineralogical analysis,three-stage BCR sequential extraction procedure,dynamic leaching test and Hakanson Potential Ecological Risk Index Method were used to access the environmental activity and potential ecological risks of heavy metals in zinc leaching residue.The results demonstrate that the environmental activity of heavy metals declines in the following order：CdZnCuAsPb.Potential ecological risk indices for single heavy metal are CdZnCuAsPb.Cd has serious potential ecological risk to the ecological environment and contributes most to the potential toxicity response indices for various heavy metals in the residue.

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.

Ecological Risk Assessment of World Heritage Sites Using RS and GIS:A Case Study of Huangshan Mountain, China

Ecological risk assessment(ERA) is an indispensable method for systematic monitoring of World Heritage Sites(WHSs) exposed to various anthropogenic factors and natural disasters. Remote sensing(RS) and geographical information systems(GIS) can eliminate many limitations in traditional ERA methods. In this study, changes in ecological risk at Huangshan Mountain, the first mixed WHS in China, over the period of 1984–2019 were explored using remote sensing images and products by considering both natural disasters and human disturbance. Results show that of the four land cover types in Huangshan Mountain, namely water, forest, building and farmland, the main land cover type is forest. During the 35 yr, lands categorised at low or relatively low ecological risk levels are dominant in Huangshan Mountain, with the lowest and highest ERIs(ecological risk index) in 1990 and 2010, respectively. The areas at the five ecological risk levels have declined as follows: relatively low > low > medium > relatively high > high. Changes in ecological risks are closely related to changes in land cover and natural disasters. Even though major natural disasters may affect the ecological risk level in the whole region, changes in land cover caused by human activities will shift the ecological risk level in some areas. Our attempts can be modified and applied to other sites, and offer policy implications for protection and preservation of WHSs.

Distribution, Enrichment and Ecological Risk Assessment of Six Elements in Bed Sediments of a Tropical River, Chottanagpur Plateau: A Spatial and Temporal Appraisal

Distribution and enrichment of six elements (iron, zinc, copper, lead, cadmium and manganese) in surface bed sediments, collected from seventeen selected locations during pre-monsoon and postmonsoon periods, of the tropical Chottanagpur plateau river Subarnarekha along with the ecological risks involved were investigated. Owing to the rich occurrence of mineral resources, the Subarnarekha river basin has a large scale presence of industrial and mining units especially in the Indian State of Jharkhand. An assessment, which involved examining distribution pattern of elements, comparative studies with sediment quality guidelines (SQGs) and geochemical background values and a sequential and integrated index analyses approach (containing contamination factor (CF), pollution load index (PLI), contamination degree (CD), enrichment factor (EF), geo-accumulation index (Igeo) and potential ecological risk index (PERI)), was followed to estimate enrichment and risks of elements in the bed sediments. Sediments collected from areas having abundance of population, industrial conglomerates and mining units recorded elevated element concentrations, which exceeded SQGs, and significantly higher values of CF, CD, PLI, EF, Igeo and PERI. Cadmium demonstrated surprising regularity in its enrichment;contributed most to the ecological risks;and high toxicity risks due to cadmium exceeded 64% of the sites. Moreover, chronic exposures of other elements would also lead to similar ecological risks. In addition to revealing potential ecological risks due to cadmium and other elements our investigation markedly highlighted anthropogenic control over sediment quality deterioration and some immediate sediment quality management strategies are needed to remediate and control river bed contamination.

Ecological Risk Assessment of Shan Xin Mining Area Based on Remote Sensing and Geography Information System Technology

In this paper, introducing new remote sensing and geographic information technology to solve the problem of data collection and analysis, this makes the study of ecological risk assessment very quick and accurate. Taking the Shan Xin mining area of the tin mine in Lengshuijiang of Hunan Province as the research object, using the remote sensing image data of three periods in 2005, 2010 and 2015, the remote sensing image is classified carefully and the landscape classification map of the mining area is obtained. The ecological risk index is introduced and the ecological risk values are sampled and interpolated on the ArcGIS platform. The ecological risk spatial distribution map based on the landscape pattern index was obtained. The ecological risk was divided into 5 levels by using the Jenks natural classification method, and each ecological risk grade area was counted. The research results show that: from year 2005 to year 2010, landscape ecological risk trend of the mining area is growing up;the trend rising area of landscape ecological risk is mainly in the southwest and northeast of the Shan Xin mining field;the area of higher and high ecological risk is increasing year by year;and the trend of dispersed development in space is obvious;the development trend of ecological risk in the mining area is rapidly increasing;in 2010 - 2015, the higher and high ecological risk area decrease slightly with the increasing of area of grassland and residential low vulnerability of landscape types;the ecological risk area showed a slow decreasing trend. The research results provide an objective reference for decision making of ecological environment governance.

Ecological risk assessment of heavy metals in surface seawater and sediment near the outlet of a zinc factory in Huludao City, Liaoning Province, China

At present, the methods widely applied to assess ecological risk of heavy metals are essentially single-point estimates in which exposure and toxicity data cannot be fully used and probabilities of adverse biological effects cannot be achieved. In this study, based on investigation of concentrations of six heavy metals(As, Hg, Pb, Cd, Cu, and Zn) in the surface seawater and sediment near the outlet of a zinc factory, located in Huludao City, Liaoning Province, China, a tiered approach consisting of several probabilistic options was used to refi ne ecological risk assessment for the individuals. A mixture of various heavy metals was detected in the surface seawater, and potential ecological risk index(PERI) was adopted to assess the potential ecological risk of heavy metals in the surface sediment. The results from all levels of aquatic ecological risk assessment in the tiered framework, ranging from comparison of single effects and exposure values to the use of distribution-based Hazard Quotient obtained through Monte Carlo simulation, are consistent with each other. Briefl y, aquatic Zn and Cu posed a clear ecological risk, while Cd, Pb, Hg, and As in the water column posed potential risk. As expected, combined ecological risk of heavy metal mixture in the surface seawater was proved signifi cantly higher than the risk caused by any individual heavy metal, calculated using the concept of total equivalent concentration. According to PERI, the severity of pollution by the six heavy metals in the surface sediment decreased in the following sequence: Cd>Hg>As>Pb>Cu>Zn, and the total heavy metals in the sediment posed a very high risk to the marine environment. This study provides a useful mathematical framework for ecological risk assessment of heavy metals.

Health risk assessment of heavy metals in soils and crops in a mining area(Au-Ag-Cutrona-oil et al.) of the Nanyang Basin, Henan Province, China

Heavy metal distribution in mining areas has always been a hot research topic due to the special environment of these areas. This study aims to explore the impact of heavy metal pollution on soils and crops in the study area, ensure the safety of local crops and the health of local residents, and provide a basis for the subsequent environmental restoration and the prevention and control of environmental pollution. Based on the analysis of the heavy metal concentrations in local soils and crops, the study investigated the spatial distribution, pollution degrees, and potential ecological risks of heavy metals in the farmland of a mining area in the southeastern Nanyang Basin, Henan province, China explored the sources of heavy metals and assessed the health risks caused by crop intake. The results of this study are as follows. The root soils of crops in the study area suffered heavy metal pollution to varying degrees. The degree of heavy metal pollution in maize fields is higher than that in wheat fields, and both types of fields suffer the most severe Cd pollution. Moreover, the root soils of different crops suffer compound pollution.The root soils in the maize fields suffer severe compound pollution at some sampling positions, whose distribution is similar to that of the mining area. Cd poses the highest potential ecological risks among all heavy metals, and the study area mainly suffers low and moderate comprehensive potential ecological risks. The principal component analysis(PCA) shows that the distribution of Zn, Cd, Pb, and As in soils of the study area is mainly affected by anthropogenic factors such as local mining activities;the distribution of Cr and Ni is primarily controlled by the local geological background;the distribution of Hg is mainly affected by local vehicle exhaust emissions, and the distribution of Cu is influenced by both human activities and the geological background. Different cereal crops in the study area are polluted with heavy metals dominated by Cd and Ni to varying degrees, especially wheat. As indicated by the health risk assessment results, the intake of maize in the study area does not pose significant human health risks;however, Cu has high risks to human health, and the compound heavy metal pollution caused by the intake of wheat in the study area poses risks to the health of both adults and children. Overall, the soils and crops in the study area suffer a high degree of heavy metal pollution, for which mining activities may be the main reason.

基于ESV-ERI-MCR评价的嘉陵江流域景观生态格局构建与优化

[目的]分析嘉陵江流域景观生态格局,旨在增强生态系统服务功能,稳固生态系统从而降低生态风险,为促进区域可持续发展提供科学依据。[方法]以长江上游重要生态屏障嘉陵江流域为研究区,基于动态当量的生态系统服务价值(ESV)评价结果识别生态源地,基于最优空间尺度的景观生态风险(ERI)评价结果确定生态阻力面,再结合最小累积阻力模型(MCR)提取的生态廊道构建生态网络。[结果](1)2005—2020年嘉陵江流域ESV呈北高南低格局和呈波动增长趋势。生态系统服务价值总计增加2.10×10~(10)元,林地贡献率最高(50%),依次为草地(25%)、耕地(14%)。(2)嘉陵江流域适宜分析粒度和幅度分别为150,750 m。2005—2020年ERI呈西北部高,中南部低格局和呈逐年降低趋势。(3)整个生态网络呈西北—东南向分布。共识别出生态源地11个,总面积36297.19 km^(2),潜在生态廊道365条,生态节点133个。其中,重要生态廊道47条,重要生态节点39个。(4)建设的重点生态保护区作为新增生态源地,为嘉陵江流域限制开发区域。新增道路型生态廊道6条,绿带型生态廊道3条,河流型生态廊道13条,生态节点24个。[结论]优化后嘉陵江流域生态网络密度增加,贯穿了全方位的生态源地,整体连通度得以提升。研究成果可为流域生态格局修复、生态保护策略和可持续发展提供新思路。

Contamination and Potential Risks of Heavy Metals in the Sediments of the Chari and Logon Rivers in N’Djamena, Chad

The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant life. The pollution of sediments by inorganic pollutants requires particularly important attention because of their toxicity, their persistence in the environment and their bioaccumulation by animal and plant living beings. This study focuses on the pollution of sediments of the Chari and Logon rivers in the city of N’Djamena by heavy metals. The objective of this study is to evaluate the degree of contamination, the geo-accumulation index and the degree of the Pollutant Loading Index of some heavy metals (Pb, Cr, Cu, Mn and Cd) and iron in the sediments of the sampled sites. The average concentrations of heavy metals and iron in the sediments are: Pb (10.00 ± 00 μg/Kg to 126 ± 16.52 μg/Kg);Cr VI (0.13 ± 00 mg/Kg to 0.21 ± 00 mg/Kg);Cd (trace);Cu (0.08 ± 0.02 mg/kg to 3.23 ± 0.64 mg/kg);Fe (0.25 ± 0.00 mg/kg to 5.79 ± 0.00 mg/kg);and Mn (0.2 ± 0.00 mg/Kg to 1.1 ± 0.00 mg/Kg);in order of highest to lowest abundance: Fe > Mn > Cd > Cu > Cr VI > Pb for the Logon;Fe > Cu > Mn > Cd > Cr VI > Pb for the Chari and Fe > Mn > Cu > Cd > Cr VI > Pb for the Confluent. The contamination factors for all heavy metals range from no contamination to low contamination for the sediments analyzed. The geo-accumulation indices indicate that the sampled sites are not polluted. The same is true for Er and RI which confirm an absence of ecological risks in the analyzed sediments.

Fractional distribution and risk assessment of heavy metal contaminated soil in vicinity of a lead/zinc mine

The pollution characteristics of Pb, Cd, Zn, Cu and Ni in soil of lead-zinc mining area were studied. The results indicate that the contamination degree followed the sequence of Cd〉Pb〉Zn〉Ni〉Cu and concentrations of Pb, Cd and Zn exceeded corresponding limits of the Chinese National Soil Environmental Quality Standard III. The soil was extremely polluted by Cd（Iego=5.26）, moderately to heavily polluted by Zn（Iego=2.38）, heavily to extremely polluted by Pb（Iego=4.13）. The results of BCR three-step sequential extraction procedure show that the active Cd, Pb and Zn were relatively high and might exert adverse effects on the plants grown in the soil, while Cu and Ni existed in soil with a relatively stable form. Potential ecological risk results indicate that soils were engaging in a high potential ecological risk by pollution of Cd and should be given rise to concern.

Evaluation of the potential risks of heavy metal contamination in rice paddy soils around an abandoned Hg mine area in Southwest China

To assess the potential ecological and health risks of trace elements(Hg,Cd,As,Mn,Sb,Pb,Cu,Ni,Cr,and Zn),a total of 138 soil samples from rice paddies were collected during the rice harvest season in the Wanshan mining area,Guizhou Province,Southwest China.Factors of the pollution load index(PLI),geo-accumulation index(I-Geo),enrichment factor(EF),and risk index(RI)were determined.High concentrations of Hg,Sb,As,Zn,Cd,Cu,and Mn were observed in the soils.The PLI,I-Geo,and EF results all showed high levels of contamination by Hg and Sb and moderate levels of contamination by As,Pb,Zn,Cu,Cd,and Mn.There was no significant contamination from Ni and Cr.The RI was very high,with Hg as the dominant pollutant,as expected,indicating that the historical large-scale Hg mining,as well as artisanal mining,has had a significant impact on the Wanshan area.Moreover,coal combustion,manganese factories,and the use of agrochemicals by the local population could also have an impact on the soil through the introduction of heavy metal loads.To address the current state of contamination,pollutant remediation and the regulation control of the anthropogenic activities in Wanshan are urgently needed.

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.

The Status Assessment and Preliminary Risk Assessment of Total Mercury in Sediments from Middle and Lower Reaches of the Yarlung Zangbo River

The occurrence and accumulation of total mercury (T-Hg) in sediments collected from the Yarlung Zangbo River (YLZB),the Lhasa River,the Niyang River and the Palongzangbu River were analyzed and the soil samples simultaneously collected from the bank were employed as control.Meanwhile,pollution status and potential ecological risk of Hg were calculated and assessed using index of geoaccumulation ( I geo ) and potential ecological risk assessment method (Er) in this study.The results showed that the T-Hg concentrations in sediments at eight sections of YLZB ranged from 4.23 to 48.1 μg/kg with mean concentration of 25.1 μg/kg,which was higher than background Hg value of soils in Tibet.T-Hg concentrations in sediments at three typical segments of YLZB were all significantly higher than those in soils collected from its bank (P<0.05).The Igeo and E r indexes revealed that the T-Hg pollution levels were slight pollution in two sections and moderate ecological risk in six sections of YLZB.Hg pollution risks also existed in the sediments of partial sections of the Lhasa River and the Niyang River,and slightly moderate Hg contamination with high ecological risk was presented in Lhasa urban district.The level of Hg in sediments of YLZB showed a notable spatial distribution characteristic with a trend of increasing firstly and then declining.Human activities played an important role in increasing Hg content in sediments of the river.

Risk Factor Assessment of Coal Mine Drainage Water on Surrounding Agricultural Soil: A Case Study at Barapukuria in Bangladesh

This study is performed to know the contamination level of heavy metals on the surrounding agricultural soils at the site of Barapukuria Coal Mine Company Limited (BCMCL). Total concentrations of eight heavy metals (Cu, As, Cd, Zn, Pb, Cr, Ni and Mn) were measured in that soil. To calculate the contamination level, the enrichment factor (EF), geoaccumulation index (Igeo) and Hakanson potential ecological risk index were done. Igeo values indicated that the study areas at all stations were suffering from moderate contamination with As. The results of enrichment factor revealed that soils in all stations were in extremely high enrichment condition by As metal. Under Hakanson potential ecological risk index, the contamination coefficient () and potential ecological risk index () were calculated. The degree of contamination at BCMCL area reflects moderate contamination. By considering the ecological risk index of a particular heavy metal, the order is as follows: Cd > As > Cu > Pb > Ni > Cr > Zn and Cd has the highest risk index and poses the greatest damage to the BCMCL area’s soil. EF, Igeo values and potential ecological risk index indicate that there is considerable As and Cd pollution, mainly caused by coal mine drainage water.

基于氧化应激生物标志物的抗生素制药废水生态风险评价

近年来我国制药产业发展迅速,由此产生了大量的制药废水。制药废水尤其是抗生素制药废水的排放,对水环境造成了潜在威胁。以石家庄市某制药厂达标排放的抗生素制药废水为研究对象,将斑马鱼暴露于不同浓度的抗生素制药废水中(体积分数为10%、40%、70%),分别于第3、6、9、12、15天测定斑马鱼肌肉组织中活性氧自由基(ROS)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽(GSH)、丙二醛(MDA)和磷酸化组蛋白H2AX(γ-H2AX)6项氧化应激生物标志物的活性或含量,并基于生物标志物测定结果计算基于改进的综合生物标志物响应指数(IBR v2)以评价其生态风险。结果表明:抗生素制药废水的胁迫使斑马鱼肌肉组织产生了氧化应激反应,但不同实验组之间的响应时间存在差异,暴露第6天时,70%实验组的ROS含量、CAT活性、GSH含量、MDA含量和γ-H2AX含量均较对照组发生了显著的变化(p<0.001),响应时间早于10%和40%实验组,表明高浓度抗生素制药废水胁迫能够快速诱导斑马鱼产生氧化应激反应;基于6项肌肉组织氧化应激生物标志物的IBR v2值计算结果显示,达标排放的抗生素制药废水仍具有较高的环境风险,且高浓度的制药废水产生的生态风险更加快速和持久。本研究可为抗生素制药废水生态风险评价和相关排放标准的制定和完善提供参考。