Soil Contamination by Heavy Metals and Evaluations on Potential Ecological Risks in an Antimony Mine

To study the status of soil quality in an antimony mine, soil samples were collected from different regions and the elements＇ contents of Sb, Cd, Cr, Cu, Zn, Pb, Hg, Ni and As were analyzed using single factor pollution index, Nemerow index and potential ecological risk index. The heavy metal contamination of soils were evaluated. The results showed that Nemerow index for each sampled point was less than 0.7, meaning a clean state. When potential ecological risk assessment was conducted, the sampled point was less than 150, belonging to light pollution.

Use of QSAR and SSD methods on deriving predicted no-effect concentrations in seawater and sediment for ten individual parent-and alkyl-PAHs and a case study on the assessment of their ecological risks from the Dalian Bay, China

Parent and alkylated polycyclic aromatic hydrocarbons(alkyl-PAHs),which are a class of important toxic components of crude oil especially in the marine environment,exhibit adverse effects on aquatic life and potentially pose a human health risk.However,the lack of chronic toxicity data is one of the hindrances for alkylPAHs when assessing their ecological risks.In this study,predicted no-effect concentrations(PNECs)in seawater and marine sediment for ten parent-and alkyl-PAHs were derived by applying species sensitivity distributions(SSDs)and quantitative structure-activity relationships(QSARs).The local area,Dalian Bay,where an oil-spilled accident happened in 2010,was chosen as a case site to assess ecological risks for ten PAHs in surface seawaters and marine sediments.Their PNECs in seawater and sediment for protecting aquatic organisms in marine ecosystems were calculated and recommended in the range of 0.012-2.79μg/L and 48.2-1337 ng/g(dry weight),respectively.Overall,the derived PNECs for the studied PAHs in seawater and marine sediment were comparable to those obtained by classical methods.Risk quotient results indicate low ecological risks to ecosystems for ten parent-and alkyl-PAHs in surface seawaters and surface sediments from the Dalian Bay.These findings provide a first insight into the PNECs and ecological risks of alkyl-PAHs,emphasizing the role of the computational toxicology in ecological risk assessments.The use of QSARs has been identified as a valuable tool for preliminarily assessing ecological risks of emerging pollutants,being more predictable of real exposure scenarios for risk assessment purposes.

Ecological Risks of Agricultural Land Capitalization and Their Prevention

The capitalization of agricultural land as an institutional innovation in land use is of great significance to revitalize China's land resources, change land use and improve land use efficiency. With the gradual implementation of the capitalization of agricultural land, however, environmental problems brought by capitalization have restricted the sustainable and efficient utilization of agricultural land. This study, from the perspective of ecology, discusses ecological risks of agricultural land capitalization, analyzes the ecological risks of agricultural land capitalization in terms of the amount of land and land quality as well as the formation mechanism of the ecological risks of agricultural land capitalization. It is found that the logic of the capital itself, the profitability of the subject and the fragility of the ecological environment are the internal and external factors of the ecological risks of agricultural land. Thereupon authors put forward policy suggestions to prevent the ecological risks of agricultural land capitalization in terms of large-scale agricultural operations in diverse forms, the development of green agriculture, the protection of agricultural land quality and green finance, with a view to resolving the ecological risks of agricultural land capitalization and realizing the benign operation of agricultural land capitalization.

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.

Distributive Characteristics of Metallic Nano-particles in China's Urban Water Bodies and their Ecological Risks

Engineering nano-materials & their impact on human health or environmental security constitute a newly emerging R&D hot spot and a key problem now urgently waiting for its solution in supporting the sustainability of China's nano-science and related technology development. At present, water bodies in Chinese cities have been seriously polluted by metallic nano-particles (MNPs) while related monitoring data are found woefully lacking throughout the country. Based on the above understanding, this article gives a round-up explanation on distributive characteristics of MNPs in the river mouths or water bodies of Chinese cities, their ecological hazards as well as our research in this regard, providing some inspiring ideas and data for control over this scourge. In addition, our exploration probes the discharge traits of MNPs themselves and the mechanism underlying its impact on water pollution.

The distribution and ecological risks of antibiotics in surface water in key cities along the lower reaches of the Yellow River:A case study of Kaifeng City,China

A large number of antibiotics have been discharged into rivers by human activities,posing a threat to aquatic ecosystems.The surface water of the Yellow River Basin also suffers antibiotic pollution,which hinders the improvement in the aquatic ecological environment.This study investigated and analyzed the characteristics and assessed the ecological risks of antibiotic pollution in surface water bodies such as canals,rivers and fish ponds in Kaifeng,Henan Province,which is a key city along the lower reaches of the Yellow River.The test results are as follows.A total of 15 types of antibiotics were detected in the surface water.They had a total antibiotic concentration of 12.2-249.9μg/L,of which tetracyclines(TCs)and quinolones accounted for the highest percentages.Six types of quinolones had detection rates of up to 100%,and doxycycline(DC)and oxytetracycline(OTC)had average concentrations of 29.52μg/L1 and 13.71μg/L,respectively.The major canals with water diverted from the Yellow River had total concentrations of quinolones and TCs of 22.0μg/L and 14.9μg/L,respectively,which were higher than those in previous studies.This phenomenon may be related to the decrease in the water flow of the Yellow River during the dry season and the increase in the antibiotic consumption of residents in the context of the Covid-19 outbreak.The upper reaches of the Huiji River in the Xiangfu District had higher antibiotic content than other districts in Kaifeng.Specifically,TCs accounted for 72.38%-91.84%of all antibiotics,and the DC and OTC concentrations were significantly higher than other antibiotics in the upper reaches.As indicated by the ecological risk assessment results,TCs had the highest ecological risks to green algae.Among them,DC had medium-high risks;TC,OTC,and chlortetracycline(CTC)had medium-high risks;trimethoprim(TMP)and lomefloxacin(LOM)had low risks;other TC antibiotics had no risk.Compared with green algae,most antibiotics showed higher ecological risks to daphnia and lower ecological risks to fish.DC and OTC dominate antibiotic pollutants in the surface water in Kaifeng City,and especially in Xiangfu District,where DC and OTC have medium-high risks.The TCs in the major Yellow River showed medium risks to both green algae and daphnia.It can be speculated that the antibiotic pollution in the Yellow River might pose a certain threat to the ecological security of water in Kaifeng City.

Potential ecological risks of Cd for different benthos in artificial reefs

Inductively coupled plasma mass spectrometry is used to detect Cdforbenthos in the artificial reef .The results show that： Cd of benthos is varied from0.011μg/L to 0.541 μg/L, and averages 0.188 ± 0.220 μg/L. The distribution of Cddecreased in the order： gonads〉 gills〉 muscle in different tissues. The enrichmentregalurity in muscle Cd of different benthos was Oratosquilla, crab, fish, shrimp,ocellatus. Its health risk factor is far less than 1, indicating that Cd hasn’t obvious healthrishks on exposure population.

Potential Ecological Risks of Heavy Metals in Soils of Shandong Peninsula Blue Economic Zone

In this research, soil samples were collected from Shandong Peninsula Blue Economic Zone to investigate heavy metal pollutions in this region and to evaluate the potential ecological risks of heavy metal pollutants based on Hakanson Potential Ecological Risk Indexes. According to the results, Hg was the primary heavy metal pollutant in Blue Economic Zone, followed by Cd, Cu, and Pb as prevalent pollutants. Heavy metals ranked in order of their pollution degrees are: Hg>Cd>Cu>Pb>Zn>Cr>As;the potential ecological risks of heavy metals follow the order of Hg>Cd>As>Pb>Cu>Cr>Zn. Heavy metal pollutions did exist in this region to a certain extent, and the percentage of potential ecological risk in “strong” and “severe” degree reached up to 13.75%. This composite risk characteristic was subject to the restriction of Hg and Cd mainly distributed in Laizhou-Zhaoyuan- Yantai, Muping-Rushan Goldmine, and other densely-populated regions, threatening the safety production of crops. The combined effects of geological background and human activities, e.g. gold mining and domestic pollutants, were the main causes of high potential ecological risks of heavy metals in local environment.

Heavy Metal Levels and Potential Ecological Risks Assessed at an Agroecosystem Site in Tropical Region

The concentrations and distribution of thirteen metals and metalloids were investigated in soils, sediments, and two biological matrices (the fish Clarias gariepisnis and the earthworm Pontoscolex corethrurus) from the CECOMAF agroecosystem, in Kinshasa, Democratic Republic of the Congo, in order to assess the impact of anthropogenic activities. The results revealed high concentrations of heavy metals, such as Cu, Zn, As, Cd, Pb, and Hg all above values recommended by sediment quality guidelines and their probable effect levels on biota. According to the calculated Enrichment Factor, soil and sediments ranked from moderately to heavily polluted by Cu, Zn, Cd, Pb and Hg. The Contamination Degree and other ecological risk indices indicated very high contamination and very high ecological risks posed by Cd and Hg, respectively. The Geoaccumulation Index indicated that current metal concentrations in the agroecosystem originated from anthropogenic activities, while the Spearman correlation matrix values indicated that Hg could originate from different sources and pathways than the other metals. It was concluded that metals from unchecked anthropogenic activities have negatively impacted agricultural activities and fish production at the CECOMAF agroecosystem. Action to reduce the contamination level and the ecological risks by remediating and preventing metal pollution in the CECOMAF agroecosystem site is recommended.

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.

Landscape ecological risk assessment and its driving factors in the Weihe River basin,China

Weihe River basin is of great significance to analyze the changes of land use pattern and landscape ecological risk and to improve the ecological basis of regional development.Based on land use data of the Weihe River basin in 2000,2010,and 2020,with the support of Aeronautical Reconnaissance Coverage Geographic Information System(ArcGIS),GeoDa,and other technologies,this study analyzed the spatial-temporal characteristics and driving factors of land use pattern and landscape ecological risk.Results showed that land use structure of the Weihe River basin has changed significantly,with the decrease of cropland and the increase of forest land and construction land.In the past 20 a,cropland has decreased by 7347.70 km2,and cropland was mainly converted into forest land,grassland,and construction land.The fragmentation and dispersion of ecological landscape pattern in the Weihe River basin were improved,and land use pattern became more concentrated.Meanwhile,landscape ecological risk of the Weihe River basin has been improved.Severe landscape ecological risk area decreased by 19,177.87 km2,high landscape ecological risk area decreased by 3904.35 km2,and moderate and low landscape ecological risk areas continued to increase.It is worth noting that landscape ecological risks in the upper reaches of the Weihe River basin are still relatively serious,especially in the contiguous areas of high ecological risk,such as Tianshui,Pingliang,Dingxi areas and some areas of Ningxia Hui Autonomous Region.Landscape ecological risk showed obvious spatial dependence,and high ecological risk area was concentrated.Among the driving factors,population density,precipitation,normalized difference vegetation index(NDVI),and their interactions are the most important factors affecting the landscape ecological risk of the Weihe River basin.The findings significantly contribute to our understanding of the ecological dynamics in the Weihe River basin,providing crucial insights for sustainable management in the region.

Microplastics in Freshwater Aquaculture Fishpond System in Yichang,China:The Occurrence,Characteristics and Potential Risks

At present,microplastics have attracted much concern worldwide,but still few researches have focused especially on aquaculture fishponds.In this study,investigations were conducted in Zhijiang(ZJ)and Yidu(YD)areas of Hubei,China,typical freshwater aquaculture bases of the middle and lower reaches of the Yangtze River,on the occurrence and distribution characteristics of microplastics in fishpond system.It was found that microplastics presented in all samples from water,sediment,fish,and fish feed.Most microplastics detected had a diameter of<1.0 mm,blue and black were the most common colors,and fiber shape was the dominant type.The most common polymer types were polyethylene(PE)and polypropylene(PP).Microplastic abundance in fish was correlated with that in sediment and water.The potential ecological risk index values indicated that water,sediment,and fish samples were under moderate pollution risk.The results of this study illustrated the microplastics pollution situation in freshwater cultured fishpond systems,and the findings presented here will serve as a reference for future investigations of the environmental risks of microplastics in aquaculture environment.

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.

Influencing Factors and Prediction of Risk of Returning to Ecological Poverty in Liupan Mountain Region,China

China has resolved its overall regional poverty in 2020 by attaining moderate societal prosperity.The country has entered a new development stage designed to achieve its second centenary goal.However,ecological fragility and risk susceptibility have increased the risk of returning to ecological poverty.In this paper,the Liupan Mountain Region of China was used as a case study,and the counties were used as the scale to reveal the spatiotempora differentiation and influcing factors of the risk of returning to poverty in study area.The indicator data for returning to ecological poverty from 2011-2020 were collected and summarized in three dimensions:ecological,economic and social.The autoregressive integrated moving average model(ARIMA)time series and exponential smoothing method(ES)were used to predict the multidimensional indicators of returning to ecological poverty for 61 counties(districts)in the Liupan Mountain Region for 2021-2030.The back propagation neural network(BPNN)and geographic information system(GIS)were used to generate the spatial distribution and time variation for the index of the risk of returning to ecological poverty(RREP index).The results show that 1)ecological factors were the main factors in the risk of returning to ecological poverty in Liupan Mountain Region.2)The RREP index for the 61 counties(districts)exhibited a downward trend from 2021-2030.The RREP index declined more in medium-and high-risk areas than in low-risk areas.From 2021 to 2025,the RREP index exhibited a slight downward trend.From 2026 to2030,the RREP index was expected to decline faster,especially from 2029-2030.3)Based on the RREP index,it can be roughly divided into three types,namely,the high-risk areas,the medium-risk areas,and the low-risk areas.The natural resource conditions in lowrisk areas of returning to ecological poverty,were better than those in medium-and high-risk areas.

Distribution, Mobility, and Health Risks Assessment of Trace Metals in River Sediments from Intense Agricultural Activity Areas in West Africa

The economy of West African countries is mainly based on agriculture. However, the trace metal(loid)s contamination status in rivers is relatively unknown in the region. In this work, 45 surface sediments collected from the Bandama, Comoé, and Bia Rivers in south and south eastern Côte d’Ivoire (West Africa), were analyzed for total metal concentrations and chemical speciation. The results showed that the river sediments were considerably contaminated by Cd and moderately contaminated by As, Cu, Pb, and Zn. Significant spatial variations were observed among the stations but not between the rivers. Metals Cd and Cu were likely to cause more ecological risks. The speciation analysis unravelled that the metal(loid)s partitioned mainly in the residual fraction, with the potential mobile fraction varying from 14% to 28%. The study calls for establishment of strict policies relative to the application of fertilizers and agrochemicals and mining activities to protect the environment and human health risks.

Ecological risk assessment and early warning of heavy metal cumulation in the soils near the Luanchuan molybdenum polymetallic mine concentration area,Henan Province,central China

The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great significance to study the ecological risk and the accumulation trends of heavy metals in the soil of mining areas for scientific prevention and control of heavy metal pollution.Taking the Taowanbeigou River Basin in the mine concentration area as the research object,the ecological pollution risk and cumulative effect of heavy metals in the soil of the basin were studied by using the comprehensive pollution index method,potential ecological risk assessment method and geoaccumulation index method.On this basis,the cumulative exceeding years of specific heavy metals were predicted by using the early warning model.The comprehensive potential ecological risk of heavy metals in the soil near the Luanchuan mine concentration area is moderate,and the single element Cd is the main ecological risk factor,with a contribution rate of 53.6%.The overall cumulative degrees of Cu and Pb in the soil are“none-moderate”,Zn and Cd are moderate,Mo has reached an extremely strong cumulative level,Hg,As and Cr risks are not obvious,and the overall cumulative risks order is Mo>Cd>Zn>Cu>Pb>Hg.According to the current accumulation rate and taking the risk screening values for soil contamination of agricultural land as the reference standard,the locations over standard rates of Cu,Zn and Cd will exceed 78%in 90years,and the over standard rate of Pb will reach approximately 57%in 200 years.The cumulative exceeding standard periods of As,Cr and Hg are generally long,which basically indicates that these elements do not pose a significant potential threat to the ecological environment.Mining activities will accelerate the accumulation of heavy metals in soil.With the continuous development of mining activities,the potential pollution risk of heavy metals in the soil of mining areas will also increase.

Factor analysis and countermeasure simulation on the socio-ecological environment risks during the development of coalbed methane:based on the DEMATEL and FCM models

The socio-ecological environmental problem caused by the development of coalbed methane(CBM)is becoming more serious,so it is very significant for accelerating the development of CBM industrialization to identify the main influential factors of socioecological environmental risks and take effective risk prevention measures.Based on the triangular fuzzy number method,this paper firstly establishes a comprehensive correlation matrix.Then,the affected factors of socio-ecological environmental risks are analyzed by the DEMATEL method during the development of CBM.Then according to the aspects of centrality and causality,the key indicators are determined.Furthermore,the scenario simulation based on the FCM,the steady-state value and the comprehensive importance of key indicators,and the core indicators are selected.Finally,the scenario simulation of risk management countermeasure is done.The results show that:①The index weights are calculated by the triangular fuzzy numbers,and the correlation matrix in DEMATEL is obtained by the weight ratio,which reduces the shortcomings and the subjectivity of traditional DEMATEL method.②The correlation matrix in FCM is established based on the comprehensive correlation matrix in the above improved DEMATEL,which not only makes the FCM model more comprehensive and reduces the difficulty that the FCM correlation matrix is obtained considering the indirect influence relationship between indicators,but also makes up for the disadvantages that DEMATEL excludes during the selection of the core indexes,which are the considerations of the dynamic change of the importance of the indicators.③The rate of forestry and grass coverage,the ratio of investment in prevention and construction,the pollution index of soil Merlot,the reliability of machinery and equipment,the standard evaluation index of major pollution factors of underground water,and the ability of personal risk prevention are the key indicators,in which the rate of forestry and grass coverage,the ratio of investment in prevention and construction,and the reliability of machinery and equipment are the core indicators and are extremely important for the management of socio-ecological environmental risks during the development of coalbed methane.④The results of the scenario simulation of risk management countermeasure show that the core variables affect the socio-ecological environmental risks through such indicators as the degree of production mechanization,the degree of demolition and resettlement,and the ratio of economic loss by the influenced mechanism analysis;the ratio of investment in prevention and construction has the greatest impact on the socio-ecological environment risks in the early stage of CMB development,while the rate of forestry and grass coverage is the most important in the middle and late stages by the influenced result analysis.Therefore,this paper puts forward some corresponding stage suggestions on the prevention and control of socio-ecological environmental risks during the CMB development.In the early stage of CMB development,the ratio of investment in prevention and construction should be increased.In the middle stage,it is very important to reduce the damage of vegetation regions and to improve the reliability of machinery and equipment;in the late stage,the investment in prevention and construction should be increased steadily and the recovery of damaged vegetation areas should be focused on.

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.

Marine ecological risk assessment for the herbicide sulfometuron-methyl based on species sensitivity distribution approach

In recent years,herbicide sulfometuron-methyl(SM)has been used to kill the invasive plant Spartina alterniflora in some coastal areas of China,which may lead to the toxic effects on non-target marine organisms.The 96-h median effective concentrations(96-h EC50)of SM on six species of marine microalgae were measured in growth inhibition tests,and were then compared with other published toxicity data,based on which a method of species sensitivity distribution(SSD)was built to estimate the hazardous concentration of SM for 5%of species(HC5)and potentially affected fraction(PAF)for a certain concentration.Results indicate that SM exhibited a high toxicity to two species of green algae(Chlorella pacifica and Dunaliella salina)with a 96-h EC50 of 0.11 and 0.13 mg/L respectively,had a medium toxicity to two species of golden algae(Diacronema viridis and Isochrysis galbana)with a 96-h EC50 of 14.24 and 21.48 mg/L respectively,and showed a low toxicity to two species of diatoms(Skeletonema costatum and Phaeodactylum tricornutum)with a 96-h EC50 of 148.99 and>100 mg/L,respectively.The estimated values of HC5 and the predicted no-effect concentrations(PNEC)for SM were 0.077 and 0.015 mg/L,respectively.According to the current dosage for killing S.alterniflora in tidal flats in Fujian Province,China,SM entering the sea by spraying might cause the acute injury or death of 14%of marine species.This hazard could last for about a month for those sensitive species.Therefore,on the premise of inhibiting the growth of this invasive plant,the dosage of SM should be reduced as much as possible to avoid severe damage to the marine ecosystem.The results provide a valuable information for marine ecological risk assessment on SM and for marine environmental management.

Ecological Risk Assessment of Heavy Metals Pollution in Soil and Lotus Seeds in Xiangtan Lotus Planting Area

In order to study the pollution characteristics and potential ecological risks of heavy metals in soil of Xiangtan lotus planting area,the contents of Mn,Cu,As,Cd,Pb and Cr in soil and lotus seeds were analyzed in six main lotus planting areas.The comprehensive potential ecological risks of heavy metals in soil were evaluated by the potential ecological hazard index.The results showed that Cd concentration(mean value)was higher than the risk screening value and lower than the risk control value,and other heavy metals were lower or close to the risk screening value.The ecological risks of each element from large to small were Cd,Pb,As,Cu,Cr and Mn.The average value of the comprehensive ecological hazard index of the six sites was 224.7,which was a medium level of pollution risk.The lotus seeds corresponding to each site were also polluted by heavy metals to a certain extent,and Cd and Pb in the seeds exceeded the standard.Through the above analysis,the heavy metals in the soil of the lotus planting area presented a medium ecological risk.In order to ensure the safety of lotus production,it is necessary to strengthen the soil testing and management in the lotus planting area.