Degree Of Heavy Metal Pollution Research Articles

Characteristics and Source Analysis of Soil Heavy Metal Pollution in a Mining Area

It is of great significance to study the degree and source of soil heavy metal pollution in geological high background value area for remediation of local contaminated soil. The 0 - 20 cm topsoil was taken around the mining area, and the contents of Pb, Zn, Ni, Cd, Hg, Cu and As in the soil were measured. Single-factor pollution index, Nemeiro comprehensive pollution index and potential ecological risk index were used to evaluate the degree of heavy metal pollution and ecological risk. Finally, multivariate statistical analysis was used to analyze the sources of soil heavy metals. The results show that the measured elements are polluted to different degrees, mainly due to the ecological environment problems caused by extensive mining development methods and inefficient utilization of resources. The key link is the release of pollutants at the source. Effectively blocking the release at the source can cut off the possibility of pollutants entering the food chain and the circulation of materials in the ecosystem. The results of potential ecological risk index showed that the potential ecological damage of seven heavy metals was ranked as follows: Cd (97.67) > Hg (68.97) > As (14.29) > Pb (11.55) > Ni (4.62) > Zn (1.61) > Cu (1.45) had a high ecological risk coefficient, and the potential comprehensive ecological risk index was 200.16 and the degree was medium. Principal component analysis shows that the sources of heavy metals are divided into Pb, Cd, As, Zn and Hg mainly from human activities such As mining, while Ni and Cu mainly come from soil parent materials, mining and agricultural activities.

КАЧЕСТВЕННЫЕ И КОЛИЧЕСТВЕННЫЕ ХАРАКТЕРИСТИКИ ПОЧВ И СВАЛОЧНОГО ГРУНТА ПОЛИГОНА ТВЕРДЫХ КОММУНАЛЬНЫХ ОТХОДОВ

The largest SMW landfill in the Irkutsk region is that in the Irkutsk city. In 2014, high heavy metal contents were registered in landfill soil samples taken at the landfill site, and it was proposed to perform monitoring outside the landfill in 2019 and determine the pollution distribution area. In this article, the comparative analysis of the degree of heavy metal pollution of the landfill soil and soil from sanitary protection zone is presented. It was established that the studied landfill soil refers to extremely hazardous soils with heavy metal contents that are up to 68 times higher than TLV. Soil samples from the landfill-affected area also contain heavy metals in high concentrations. The manufacturing supervision of the SMW landfill should include the continuous observation of the soil, water, and air condition in the zone of possible impact of the landfill for taking timely environmental protection measures and preventing further negative impact of the landfill on the ecosystem.

ОЦЕНКА ЗАГРЯЗНЕНИЯ ТЯЖЕЛЫМИ МЕТАЛЛАМИ ПОЧВ ГОРОДА ПЕТРОПАВЛОВСКА-КАМЧАТСКОГО, КАМЧАТСКИЙ КРАЙ

The results of determining the gross content of zinc, copper and lead in the surface soil layer, collected in Petropavlovsk-Kamchatsky, are presented in the paper. Based on them the heavy metal pollution degree assessment in different places of the city during 2017–2020 is given. It was found that almost everywhere the lead content in soils corresponded to a very high or high degree of contamination. According to the concentration of copper and zinc, the soils were classified as low and medium polluted. During 2017–2020 an increase of copper and zinc concentration in soils was registered. The dynamics of changes in lead concentration, on the contrary, was poorly expressed during 2017–2018. In 2020 a decrease in its content was found in all observed areas. According to the integrated pollution indexes PLI and NPI, the most polluted soils were identified in such areas as ‟Hospital” (2017),‟Botanicheskiy Pereulok” (2018), ‟Stadium Spartak” (2020). All city soils were characterized by a weak degree of potential environmental risk resulting from heavy metal pollution. The obtained data can be used to monitor heavy metal contamination of urbanized territories soils in Kamchatka Territory.

Distribution characteristics and risk of heavy metals and microbial community composition around the Wanshan mercury mine in Southwest China

The Wanshan mercury (Hg) mine in Guizhou Province is one of the main Hg-producing mines in China, resulting in serious Hg pollution in soil and wastewater. Therefore, the present study is mainly aimed to investigate the current degree of heavy metal pollution and compared the microbial diversity in the Wanshan Hg mine and its surrounding environment. The results showed the distribution of the pollution load index values was low in the west and high in the east. The northwestern (Aozhai River), northern (Meizi Stream), and southwestern parts of the study area and the area surrounding Erkeng did not reach moderate pollution. Mercury accounted for the majority of the potential ecological risk index values, reaching 67.62%, while the proportions of Cd and As were 15.75% and 10.75%, respectively. Mercury was found mainly in a residual state, which had an average proportion of 71.09%. In the three regions, Proteobacteria and Actinobacteria had the highest relative abundances. According to linear discriminant analysis effect size, the indicator species in the Hg mining area, woodland and cultivated land was f__67–14 (belonging to a family of Solirubrobacterales), Reyranellales and Reyranellaceae, Intrasporangiaceae, respectively. In summary, this study for the very first time estimated that the higher Hg, Cd and As pollution existed in Wanshan Hg mine since their concentration in the all soil samples totally exceeded the standard value (GB15618-2018), while Cd and As pollution in soil was commonly ignored by the previous study. The cultivated land had higher community richness than the mercury mining district and woodland. Our results suggested that the relevant local departments need to take more active measures to solve the problem of high levels of Hg, Cd, and As in the local soil, and prevent their adverse effects on humans.

Effects of heavy metals on microorganisms and enzymes in soils of lead–zinc tailing ponds

Taking the soil around the lead-zinc tailings pound in the upper reaches of the Hanjiang River in Shaanxi Province as the research object, with tailings pond as the center, seven different belt zones were divided outwards, the contents of Pb, Cu, Zn, V, Ni, Cd in soil were analyzed, as well as soil basic respiration (SBR), microbial biomass carbon (MBC), microbial metabolic quotient (MMQ), and the activities of catalase, urease, cellulase, invertase and neutral phosphatase were also determined. The purpose was to reveal the intrinsic relationship between soil microbial, enzyme activities and heavy metal pollution, and to establish the characterization system of enzyme activities, soil heavy metal pollution degree, as well as microbial parameters. The results showed that: (1) The potential ecological risk index of six heavy metals was ranked as Cd > Cu > Pb > Ni > Zn > V. Cd was a high potential ecological risk, Cu was a medium potential ecological risk, and Zn, Pb, V and Ni were low potential ecological risk. The comprehensive evaluation result of Hakanson's potential ecological hazard index showed that, Zone I was of high potential risk level, Zone II, III and IV were of medium risk level, and Zone V, VI and VII were of low level. (2) Microbial biomass carbon (MBC) had a significant negative correlation or extremely significant negative correlation with 6 heavy metals, and microbial metabolic quotient (MMQ) had a significant positive correlation or extremely significant positive correlation with 6 heavy metals. MBC and MMQ were effective microbiological indexes to measure the quality status of soil, while SBR was not. (3) Catalase, cellulase, sucrase and neutral phosphatase activity had significant negative correlation with the contents of 6 heavy metals, and they could replicate the pollution degree of substantial metals in the soil. However, urease had no significant correlation with the contents of 6 heavy metals, which could not reflect the pollution degree of soil heavy metals.

Foliar dust as a reliable environmental monitor of heavy metal pollution in comparison to plant leaves and soil in urban areas

Pollution of atmospheric particulate matter carrying heavy metals has posed a great threat to various ecosystem compartments. Here, a total of 540 samples from four ecosystem compartments (plant leaves, foliar dust, surface soil, and subsoil) were collected in urban soil-plant systems to characterize the heavy metal concentration and composition of foliar dust, to verify the suitability of foliar dust as an environmental monitor, and to explore the importance of foliar dust in shaping the heavy metal composition in plant leaves. We found that the concentrations of all detected elements (lead, zinc, copper, chromium, nickel, and manganese) in foliar dust were the highest among the four ecosystem compartments. The mass of element per unit leaf area, considering both the dust retention amount and the heavy metal concentration of foliar dust, had significant positive correlations with the degree of heavy metal pollution in soil. Foliar dust could reflect ambient elemental composition most reliably among the four ecosystem compartments. The above findings show that foliar dust is more suitable for environmental monitoring than soil and plant materials in urban areas. In addition, the elemental composition of plant leaves differed significantly with different soil-plant systems although species identity dominated the leaf elemental composition. The variation partitioning model and the partial correlation analysis confirm that foliar dust plays a more important role in shaping the elemental composition of plant leaves than soil. This study provides a new way for environmental pollution monitoring and contributes to a comprehensive understanding of atmospheric particulate matter.

Study on the Predictive Algorithm of Plant Restoration under Heavy Metals

Heavy metal pollution of soil is becoming a more serious issue globally. Heavy metal contamination of the soil environment is inevitable as a result of the rapid and extensive growth of industry and agriculture, resulting in unfavorable environmental circumstances for both the flora and fauna. Traditional approaches for collecting field sampling with laboratory testing of soil heavy metals are restricted not only by their time and cost but also by their inability to gather sufficient information about the spatial distribution characteristics of heavy metals in soil over a vast area. The continuous development of the urban industrial processes leads to the degree of heavy metal pollution in urban gardens. For soil monitoring and cleanup, having quick and accurate access to heavy metal concentration data is very crucial and critical. In order to improve the restoration ability of garden heavy metal pollution, a new algorithm to predict plant restoration ability under the garden heavy metal pollution environment is put forward in this study. Firstly, we analyzed the composition of garden heavy metal pollution and the harm of garden heavy metal pollution. Secondly, we identified the restoration technology of garden heavy metal pollution to plants, determine the level of garden heavy metal pollution with the help of the land accumulation index method, and reflect the average pollution water level of garden heavy metal elements with the help of Numero comprehensive pollution heatstroke. On this basis, the plant repairability prediction model was constructed with the help of wavelet function, to predict the plant repairability under garden heavy metal pollution environment and to complete the prediction of plant repairability under garden heavy metal pollution environment. The experimental results show that the proposed method was better than the traditional approaches in terms of prediction accuracy and is also less time-consuming.

Evaluation of Contamination and Accumulation of Heavy Metals in the Dhaleswari River Sediments, Bangladesh

The Dhaleswari river is considered as one of the most important rivers of Bangladesh due to its geographical location and ecological services. The present study attempts to evaluate the degree of heavy metal pollution, contamination, and accumulative behavior in the sediment of the Dhaleswari river. The sediment samples were collected from fifteen different locations of the Dhaleswari river. Heavy metals were analyzed using the Flame Atomic Spectrophotometer (FAAS). The mean concentrations of Zn, Cu, Cr, Pb and Cd were 131.9, 48.89, 43.16, 33.23 and 0.37 mgkg-1, respectively. According to the United States Environmental Protection Agency (USEPA) Sediment Quality Guideline, the sediment of most of the locations were not polluted for Pb and Cd. But S-11 location for Cd (0.8 mg kg-1) was highly polluted. For Cr, Cu and Zn, maximum locations were moderately polluted. Although the geo-accumulation index (Igeo) values of Dhaleswari river sediments showed almost no severe contamination for most of the sampling locations, the pollution load index (PLI) values showed that most of the sampling sites were contaminated for all heavy metals tested. Moreover, for all measured heavy metals, the mean Contamination Factor (CF) values indicated moderate pollution, except for Cr, which suggested low pollution. The Pearson’s correlation coefficient matrix among the selected heavy metals of Dhaleswari river sediment showed no significant correlation among each other. Therefore, regular monitoring of the heavy metal concentration of the Dhaleshwari river sediment from different location is necessary to identify the sources of pollution so that proper initiative could be taken to prevent heavy metal pollution.

Spatial distribution, risk assessment, and source identification of pollutants around gold tailings ponds: a case study in Pinggu District, Beijing, China

This work investigated heavy metal and cyanide pollution in surface soils and edible plants around Yanzhuang gold tailings ponds in the region of Yanzhuang Village in Pinggu District, Beijing. Surface soil samples were collected from 33 sites around gold tailings ponds, and concentrations of seven heavy metals (i.e., Sb, As, Cd, Cu, Pb, Zn, and Hg) and cyanide were analyzed to determine their spatial distributions, pollution degrees, and sources. The potential ecological risks of As, Cd, Cu, Pb, Zn, and Hg were preliminarily assessed. The results showed that the mean cyanide, Sb, As, Cd, Cu, and Pb concentrations were higher than the standard values. The pollutant concentrations around the tailings ponds were high and decreased with increasing distance from the ponds. The single pollution index indicated that cyanide, As, and Cd were the main pollutants. The Nemerow pollution index revealed a large region and serious degree of heavy metal pollution in soils. The potential ecological risk level of the study area was moderate, with Cd and As posing the main risks. Multivariate statistical analysis suggested that the heavy metal and cyanide pollution present mainly derived from gold tailings, with agricultural pollution also had a certain effect. However, the 12 edible plants sampled were basically not polluted.

Pollution Distribution and Ecological Risk Assessment of Heavy Metals in River Sediments from the Ancient Town of Suzhou

The contents of heavy metals (Cd, Cu, Cr, As, Mn, Ni, Pb, and Zn) in sediments from 20 representative sections of the ancient town of Suzhou were analyzed to determine the pollution degree and potential ecological risk, and pollution sources were identified. The results showed that the average concentrations of Cd, Cu, Cr, As, Mn, Ni, Pb, and Zn in river sediments from the ancient town of Suzhou were 1.1, 142.6, 90.2, 17.2, 800.1, 63.3, 199.1, and 384.2 mg·kg-1, respectively, and the proportions of sampling points that exceeded the soil background value of Jiangsu Province were 100%, 100%, 65%, 95%, 70%, 100%, 95%, and 100%, respectively. The geo-accumulation index indicated that the pollution degree of heavy metals followed the order of Pb > Cd > Cu > Zn > Cr > Ni > As > Mn. In general, high Pb pollution, moderate Cd, Cu, Zn, and Cr pollution, slight Ni and As pollution, and no Mn pollution were observed. The potential ecological risk index for heavy metals was determined to follow the order of Cd > Pb > Cu > As > Ni > Zn > Cr > Mn. Generally, Cd, Pb, and Cu presented moderate potential ecological risk, and the others presented low potential ecological risk. The average concentration of heavy metals, geo-accumulation index, and potential ecological risk index of river sediments in the northern and southern of ancient town were all higher than that of Ganjiang River and Huancheng River, indicating that the control of heavy metals should focus on the inner part of the ancient town. According to correlation analysis and principal component analysis, Cd, Cu, Cr, As, Ni, Pb, and Zn might be derived from man-made factors such as fertilizer, road aging, tire wear, exhaust emissions and so on, which Mn was mainly derived from natural factors.

Biochemical and genetic modulations of Rhabdosargus haffara against high pollution marine environment with heavy metals

Heavy metal pollution may affect the aquatic organisms at the cellular level through the changing production of mRNA and proteins. To prove the extent of pollution in the study area; seven heavy metals: Zn, Cu, Cd, Pb, Fe, Ni, and Mn were measured using atomic absorption spectrophotometer in Rhabdosargus haffara (haffara seabream) fish liver, muscle, and gills tissues collected from northern of Suez Gulf in Egypt during winter and summer seasons. The field study area was divided according to the degree of heavy metal pollution in less and highly polluted areas. Elevated values of most studied metals concentrations were detected in fish tissues belong to the high polluted sites as compared to the less polluted sites. A study was performed between high and less polluted areas samples; to evaluate the effect of heavy metal pollution on Cytochrome c oxidase mRNA expression and alkaline phosphatase enzymatic activity in fish liver tissue. Using qRT- PCR, evidence of an increase in Cytochrome c oxidase in fish livers was detected in the highly polluted areas samples than those from less polluted. Relative quantitation of COX-1 was significantly highly expressed in liver tissue sampled from high polluted sources in response to heavy metal pollution as compared to less polluted sources for mRNA. Moreover, there was a high significant difference between winter and summer seasons in high polluted study areas than less polluted source samples

Comprehensive evaluation of environmental availability, pollution level and leaching heavy metals behavior in non-ferrous metal tailings

Amounts of abandoned non-ferrous metal tailings(NMT) piled in the open air are released under geochemistry and migrated to the surrounding environment, causing severe harm to the environment and human health. It is essential to evaluate the heavy metal pollution of NMT. In this study, RAC, Igeo, EF, and RI were used to evaluate the heavy metal pollution risk of NMT. To uniformly simplify the four evaluation results into a comprehensive evaluation result that can reflect the degree of heavy metal pollution risk. Assuming heavy metals' concentration, occurrence, and mobility make the same contribution to the degree of heavy metal pollution. Score the above four evaluation results according to the pollution level, and then weigh the scores to obtain a complete integral result: CRSMo (17) >CRSCd (13) >CRSPb (11) >CRSSr(8) >CRSMn(7) >CRSCu(5) >CRSNi(4) >CRSCr(3) = CRSZn(3). Five higher risk heavy metal elements Mo, Cd, Pb, Sr, and Mn, were found. Cu, Ni, Cr, and Zn are at lower risk. The results showed that Mo, Mn, and Sr's evaluation is more accurate. Pb and Cd have not reached the detection limit for the time being, indicating that the release of heavy metal elements in tailings is not only related to the total concentration, occurrence state, and mobility of heavy metals but also affected by the pH of the tailings. This study's most significant finding is to propose a comprehensive integration result of pollution risk levels based on RAC, Igeo, EF, and RI as the comprehensive evaluation result of heavy metal pollution risk. Simultaneously, this research is also a valuable supplement to the existing risk assessment of heavy metal pollution.

Characteristics of Heavy Metal Pollution and Ecological Risk Evaluation of Indoor Dust from Urban and Rural Areas in Taiyuan City During the Heating Season

The presence of heavy metals in indoor dust is a world-wide concern owing to its negative impact on humans. In this study, we collected indoor dust samples from urban and rural residential areas during the heating season in Taiyuan City. We then identified the concentrations of 11 heavy metals (Cd, Co, Cr, Pb, Mn, Ni, Cu, Zn, V, As, and Hg) using inductively coupled plasma-mass spectrometry. Based on the concentrations, we categorized the pollution levels of indoor dust using the geo-accumulation index and the pollution load index. We further identified the sources of heavy metals using the enrichment factor and principal component analysis. Finally, we evaluated the potential ecological risks of heavy metals via the potential ecological index. The results illustrated that ① with the exception of Co, Mn, and V, the mean concentrations of Cd, Cr, Cu, Ni, Pb, As, Zn, and Hg in indoor dust were higher than the soil background values of Shanxi Province. There was a significant difference (P<0.05) in the concentrations of Co, Cr, Cu, Mn, Ni, and Hg between the urban and rural areas. ② Overall, the pollution degree of heavy metals in indoor dust was identified as moderate in the urban area of Taiyuan City, but slight in the rural area. The indoor dust sample in the urban area was not contaminated by Co, Mn, and V. However, it was slightly polluted by As, Ni, and Hg. In addition, it was close to moderately polluted by Cd, Cr, Cu, Pb, and Zn. In the rural area, the pollution degrees of all the metals, except for Hg and V, in indoor dust were lower than those in the urban area. ③ The As, Cd, Cu, Pb, Zn, and Hg in indoor dust for both urban and rural areas might have mainly originated from anthropogenic sources. The pollution sources were mainly transportation and industry in the urban area and coal combustion and indoor smoking in the rural area. The Co, Cr, Mn, Ni, and V in indoor dust in Taiyuan City might have mainly originated from natural sources. ④ The ecological risk of heavy metal pollution in indoor dust for both the urban and rural areas of Taiyuan City was relatively high, with integrated ecological risk indexes of 359.43 and 471.02 in the urban and rural areas, respectively. In addition, Cd and Hg were the largest contributors.

Pollution Source Analysis of Heavy Metal and Ecological Risk Assessment in Urban Fringe

With the rapid development of modern urbanization, the unreasonable industrial structure has impacted urban environment, which greatly restricts the use of land resources safely. Especially in some cities with rapid urbanization, on the one hand, urban development requires a large amount of lands; on the other hand, the urban environment exceeds its bearing capacity, and human settlements environment have been negatively affected. Taking the typical urban fringe of Xi’an as the research area, this study detected Cd, Cr, Cu, Ni, Pb and Zn combined with GIS, RS and GPS technologies. Totally 26 sample points were collected. The pollution index method (single pollution index, Nemerow comprehensive pollution index method), geo-accumulation index method and potential ecological risk index method were used to evaluate the results, and the pollution sources were analysed. According to the analysis results, Cd, Pb and Zn existed obviously ecological risks. The Pb pollution of each sample point was quite different. Sample points 1-13 were located in the east of the research area, mainly distributed on both sides of the traffic road. Pb pollution was relatively serious. The average value of Igeo (Pb) reached 4.20, which belongs to strong pollution - extremely strong pollution. The heavy metal pollution of Zn was universal, however, the toxicity response parameter of Zn is low, Tr i=1, so the ecological risk was not significant. The detection rate of Cd was only 11.5%, but the value was much higher than background value, which should be paid attention to. The results showed that there are different degrees of heavy metal pollution and potential ecological risks in the research area, which supported the safe use of land in urban fringe areas.

ТЯЖЕЛЫЕ МЕТАЛЛЫ В ГОРОДСКИХ ПОЧВАХ: ОЦЕНКА СОДЕРЖАНИЯ И ЭКОЛОГИЧЕСКОГО РИСКА

Актуальность исследования обусловлена необходимостью выявления особенностей накопления тяжелых металлов в почвах урболандшафтов Владивостока и Уссурийска и установления величины потенциального экологического риска. Целью работы является оценка геохимического состояния почв различных функциональных зон урболандшафтов с использованием нескольких индексов загрязнения. Методы. Валовое содержание элементов в почвах определяли методом рентгенфлуоресцентного анализа на спектрометре EDX-800HS (Shimadzu). Результаты. Под влиянием сильной техногенной нагрузки в верхних горизонтах почв урболандшафтов в наибольшей степени накапливаются хром, медь, цинк и свинец. Содержание ванадия, кобальта и никеля сравнимо с кларком или ниже его. Средние и максимальные значения комплексных коэффициентов загрязнения PLI и NPI свидетельствуют о деградации поверхностного слоя городских почв и сильной степени загрязнения тяжелыми металлами. Потенциальный экологический риск колеблется от незначительного до среднего. Степень загрязнения почв различных функциональных зон увеличивается в следующем ряду: рекреационная&lt;многоэтажной застройки&lt;транспортно-селитебная&lt;малоэтажной застройки, уровень загрязнения варьирует от оценки «чиста почва» до оценки «сильно загрязненная почва». В некоторых почвах рекреационной зоны выявлена слабая аккумуляция хрома, цинка и меди. В почвах зоны многоэтажной застройки во Владивостоке обнаружено накопление хрома, меди, свинца и цинка (от слабого до среднего), а в Уссурийске отмечено только накопление меди. В почвах транспортно-селитебной зоны и зоны малоэтажной застройки с разной степенью интенсивности аккумулируются хром, медь, свинец и цинк. Более высокие значения как индивидуальных (Igeo, EF, PI), так и комплексных показателей загрязнения (NPI, PLI, PERI) выявлены в почвах Владивосток.

Pollution Characteristics and Risk Assessment of Heavy Metal Elements in Sediment in the West Lake of Hengshui Lake

21 sampling points were set in the West Lake of Hengshui Lake including 20 fish ponds and 1 natural pond to analyze the contents distribution of heavy metal elements including Cr, Zn, Pb, Cu, Cd, Hg, As, and Sb in sediment. The degree of heavy metal pollution was evaluated by the geoaccumulation index (Igeo) method. The results showed that the concentrations of Cr, Zn, Pb, Cu, Cd, and Hg at in all sampling points of the fish ponds were lower than soil risk screening values of agricultural land in soil environmental quality: risk control standard for soil contamination of agricultural land (trial) (GB 15618‐2018). The concentrations of As at 5 sampling points were higher than soil risk screening values and lower than soil risk control values of agricultural land in GB 15618‐2018. The concentrations of Sb were lower than soil risk screening values of construction land in soil environmental quality: risk control standard for soil contamination of development land (trial) (GB 36600‐2018). The evaluation results of the geoaccumulation index method showed that the pollution degrees of Cd, Pb, and Hg were moderately contaminated in general, the pollution degree of Cu was uncontaminated to moderately contaminated in general, the pollution degrees of Cr and As were uncontaminated to moderately contaminated in some sampling points, and Zn and Sb could be regarded as uncontaminated in sediment of the fish ponds in the West Lake of Hengshui Lake. Otherwise, the average contents of other heavy metal elements in sediment of the fish ponds in the West Lake of Hengshui Lake were higher than the background value of soil in Hebei Province (BVSH) except for Zn and Sb. The average contents of seven heavy metal elements in sediment of the natural pond in the West Lake of Hengshui Lake were lower than BVSH except for Cr. The result can be regarded as no pollution in the natural pond because the values of Igeo were all lower than 0. The heavy metal pollution in the sediment of the West Lake of Hengshui Lake may be due to the introduction of feeding. The water environment of the West Lake of Hengshui Lake can be effectively improved by cleaning up the sediment of fish ponds and “returning fishing to wetland.”

Application of BP - ANN model in evaluation of soil quality in the arid area, northwest China

Soil quality evaluation is an effective way to improve ecological environment quality of soil and to perfect management system as well as keep its productivity of the soil sustainable. However, in arid areas, the comprehensive study of soil quality has been paid little attention. This paper aims to classify and evaluate comprehensive soil quality which combined heavy metal contamination with soil nutrients in the arid area, and to explore the natural environmental controlling factors of soil quality under regional differences. Taking Hexi area, a typical arid area in northwest China, as the study area, the comprehensive evaluation model of soil quality based on back propagation artificial neural network (BP - ANN) was proposed. The results showed that the accuracies of the validated models were both more than 97 %. The soil quality in Hexi area was divided into six classes: IA, IB, IC, IIA, IIB, IIC (The number (I and II) represents the degree of heavy metal pollution, the larger the number, the higher the pollution degree; the letter (A, B, and C) represents the nutrient level, the latter the letter, the more barren the nutrient). Most of the samples were classified as IB and IC, indicating that the soil quality was good with mild heavy metal contamination and poorer nutrients. Group analysis was used to explore the impact of natural environmental factors on soil quality under different environmental characteristics through linear regression modeling. The results showed that elevation, annual mean cumulative precipitation, slope and topographic wetness index were the environmental controlling factors of the soil quality for all samples. Besides, the other important factors affecting soil quality in group 1 were: annual mean temperature and soil type. For group 2 it was LUCC (Land Use Cover Change). This study is of great significance to classify and define the soil quality, to maintain and improve agricultural production and soil ecological health in arid areas.

Pollution and Ecological Risk Assessment and Source Apportionment of Heavy Metals in Sediments of Qingliangshan Reservoir in the Meijiang Basin

Reservoir sediment is an important sink for pollutants such as heavy metals. Under the changes in acid-base and redox conditions, there is a potential risk of heavy metals release into the water environment, which are transmitted through the food chain and threaten human health. Therefore, this study investigates the Qingliangshan Reservoir in the Meijiang River Basin, and conducts research concerning the contents and speciation of heavy metals in the sediments, potential ecological risks, and source apportionment. This study found that the content of heavy metals in the sediments of the reservoir area was in the order:Xitian tributary > dam front and reservoir center > Xintian-Baishui tributary. There is a large difference in the speciation of heavy metals in the sediments. Zn is mainly acid-soluble and in the residual state, Pb is mainly in an Fe/Mn oxide bound state, Cd is mainly in an acid-soluble state, and Cu, Ni, and Cr are in the residual state. Mainly, the percentage of bioavailable states are Cd(89%) > Pb(76%) > Zn(54%) > Cu(43%) > Ni(28%) > Cr(10%). The geoaccumulation index method shows that the pollution degree of heavy metal elements in reservoir sediments is in the order Cd > Pb > Zn > Cu > Cr > Ni, and the potential hazard ecological index method shows that the pollution degree of heavy metals is Cd > Pb > Cu > Ni > Zn > Cr. The potential ecological risk of Cd in the reservoir sediments is the largest, and the biological impact is greatest. Correlation analysis and principal component analysis results show that heavy metals Cu, Zn, Pb, and Cd in reservoir sediments are mainly from agricultural pollution, and Ni and Cr are mainly from natural background. Combined with the analysis of soil heavy metal content in the watershed, heavy metal pollution in the Qingliangshan Reservoir sediments originates from the effect of rainfall runoff and the use of agricultural chemical fertilizers before flooding in the upstream of the reservoir tributaries. There are significant spatial differences in heavy metal pollution in the sediments of the reservoir area. The Xintian-Baishui River recharge area is the least polluted, and it is closely related to the land use in the controlled watershed, which is mainly forest land, with fewer sources of pollution. The Xitian River replenishment area has the heaviest pollution. It controls many tea gardens and farmlands in the watershed, and the load of external fertilizer pollution is the largest. The pollution degree of heavy metals in front of the dam and the center of the reservoir area is between the two tributary replenishment areas, showing an obvious mixing effect.

Effects of heavy metal pollution on farmland soils and crops: A case study of the Xiaoqinling Gold Belt, China

ABSTRACT This paper focuses on the heavy metal enrichment and heavy metal pollution degree associated with mining activities in some crops and the soils of different parent materials in the Xiaoqinling Gold Belt. According to the geochemical analysis results of the soils observed in the gold belt, the soils are most highly enriched in Pb, followed by Cr, Cu, and Zn. Furthermore, they are relatively poor in Hg, Cd, and As. It is also shown that the heavy metals in all kinds of soils have the same geochemical characteristics in the gold belt. As for the crops (such as corn and wheat) in the gold belt, Zn and Cu are the most abundant elements, followed by Pb and Cr. Meanwhile, Hg, Cd, and As were found to have relatively low concentrations in the crops. The heavy metals in wheat and corn have the same geochemical characteristics in the gold belt in general. Compared to the aeolian loess soils and the crops therein, heavy metals are more enriched in diluvial and alluvial soils and the crops therein. As shown by relevant studies, the Hg, Pb, Cd, Cu, and Zn pollution are mainly caused by mining activities. Corn and wheat in the gold belt have a high tendency of risk exposure to heavy metal pollution since they are mostly affected by mining activities and feature high background values of heavy metal concentrations. Furthermore, wheat is more liable to be enriched in heavy metals than corn is grown in all types of soils. The Hg pollution in soils leads to Hg accumulation, increasing the risk of Hg uptake in crops, and further affecting human health. This study will provide a scientific basis for the control and management of heavy metals in farmland soils of mining areas.

Source identification and pollution degree of deposited dust on green space in Tehran.

The information about concentration, sources, and pollution degree of heavy metals belong to deposited dust (DS) can be used for decision-making in air quality control, removal role of green space, and urban forest management. The objectives of the study were to identify and evaluate DS pollution degree with the introduction of a new index. DS samples were collected from five tree species. The concentration of heavy metals and pollution degree of DS were evaluated by enrichment factors (EF), geoaccumulation index (Igeo), modified degrees of contamination (mCd), and a new comprehensive index as weighted degree of contamination factor (wCd). The values of EF showed that all samples were significant to extremely high enrichment and DS samples were emitted from anthropogenic activities. Igeo values indicated that DS samples were polluted by Cd (80-97%) and Pb (100%). In addition, mCd results showed more than 67% of samples were unpolluted. There was a clear fact that Igeo results showed high pollution levels for Pb, Cd, and low for Ni, and the mCd results were incompatible with them. When all heavy metals were used without their importance to mCd, calculation can cause bias from reality. For this reason, the new index was suggested as wCd for all heavy metals that its results showed high to very high degree of pollution and that it was compatible with other indices results.