Metals In Agricultural Soils Research Articles

Contamination Assessment of Heavy Metals in Agricultural Soil, in the Liwa Area (UAE).

The Liwa area is a primary food production area in the United Arab Emirates (UAE) and has intensively been used for agriculture. This study investigates the pollution levels with heavy metals in agricultural soils from the Liwa area. Thirty-two soil samples were analyzed for Mn, Zn, Cr, Ni, Cu, Pb, Cd, Co, and As. Results revealed that heavy metal levels varied in the ranges 220.02–311.21, 42.39–66.92, 43.43–71.55, 32.86–52.12, 10.29–21.70, 2.83–8.84, 0.46–0.69, 0.03–0.37 mg/kg for Mn, Zn, Cr, Ni, Cu, Pb, Cd, Co, and As, respectively. All samples presented low As concentrations with an average of 0.01 mg/kg. The variations in bulk metal contents in the soil samples were related to multiple sources, including agrochemicals, atmospheric dust containing heavy metals, and traffic-related metals. Enrichment factor analysis indicates that Cd, Ni, Zn, and Cr were highly enriched in soils, and they could originate from non-crustal sources. Based on the geo-accumulation index (Igeo), the soil samples appeared uncontaminated with Mn, Cr, Zn, Pb, Co, As, Cu, uncontaminated to moderately contaminated with Ni and moderately contaminated with Cd. The contamination factors suggest low contamination, except for Ni, which showed moderate contamination. The average pollution load index (PLI) revealed unpolluted to low pollution of all soil samples. The ecological risk assessment (PERI) showed that all heavy metals posed a low risk, except for Cd which exhibited a high ecological risk.

Determination of heavy metal content and pollution indices in the agricultural soils using laser ablation inductively coupled plasma mass spectrometry.

In this study, we determined the concentrations of heavy metals in the agricultural soils of Kafr El-Zayat city using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The LA-ICP-MS performance was firstly evaluated by analyzing appropriate reference materials and comparing the concentration values found to those of the reference values. LA-ICP-MS was then applied to examine the content of 21 elements (Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Rb, Sr, Mo, Sn, Ba, Pb, Th, and U) in 16 collected agricultural soil samples from Egypt. The soil quality was assessed by calculating the contamination factor (CF), enrichment factor (EF), and the geo-accumulation index (Igeo) of the measured heavy metals. The average concentrations of V, Cr, Co, Ni, and Cu were higher than the average worldwide background concentrations and exceeded the Canadian soil quality guidelines with values of 162.8, 113.3, 42.2, 88.1, and 70.6 μg/g, respectively. Multivariate analysis was applied to investigate the correlation and sources of heavy metals in agricultural soils. Cluster analysis indicated the clustering of heavy metals into three groups: Cr and Mo; Fe and Mn; and V, Ni, Co, Cu, Zn, and Pb. The results of principal component analysis (PCA) agreed with those of the cluster analysis and yielded three components that explained 81.13% of the total variance. The contamination factor (CF) of soils from all sampling sites showed moderate contamination.

Metal transporters in organelles and their roles in heavy metal transportation and sequestration mechanisms in plants

Heavy metal toxicity is one of the major concerns for agriculture and health. Accumulation of toxic heavy metals at high concentrations in edible parts of crop plants is the primary cause of disease in humans and cattle. A dramatic increase in industrialization, urbanization, and other high anthropogenic activities has led to the accumulation of heavy metals in agricultural soil, which has consequently disrupted soil conditions and affected crop yield. By now, plants have developed several mechanisms to cope with heavy metal stress. However, not all plants are equally effective in dealing with the toxicity of high heavy metal concentrations. Plants have modified their anatomy, morphophysiology, and molecular networks to survive under changing environmental conditions. Heavy metal sequestration is one of the essential processes evolved by some plants to deal with heavy metals' toxic concentration. Some plants even have the ability to accumulate metals in high quantities in the shoots/organelles without toxic effects. For intercellular and interorganeller metal transport, plants harbor spatially distributed various transporters which mainly help in uptake, translocation, and redistribution of metals. This review discusses different heavy metal transporters in different organelles and their roles in metal sequestration and redistribution to help plants cope with heavy metal stress. A good understanding of the processes at stake helps in developing more tolerant crops without affecting their productivity.

Source Identification of Heavy Metals in Surface Paddy Soils Using Accumulated Elemental Ratios Coupled with MLR.

Source identification of heavy metals in agricultural soils using small sample sizes, simple experimental procedures, and convenient analysis is urgently required. This study employed a simple source identification model using a visual comparison via radar plots, cluster analysis, principal component analysis, and a multiple linear regression model to determine the source of heavy metal pollution in soil samples from the Chang-Zhu-Tan urban agglomeration area of China. The elemental compositions of major pollution sources (atmospheric deposition, organic fertilizer, irrigation water, and tailings) were compared with soil samples from 11 study locations and the model was used to determine the relative contribution of different pollution sources at each sample site. The results showed that the model successfully calculated the contribution of different pollution sources at each site based on the pollution characteristics and contaminant transport rules of the region. The proposed method overcomes the requirement for extensive data and complex experimental procedures. Furthermore, the model can determine the source of heavy metal contamination in single or small plots, which is important for the prevention and control of heavy metal soil pollution and remediation at the plot scale.

An integrated method for source apportionment of heavy metal(loid)s in agricultural soils and model uncertainty analysis.

Elevated concentrations of heavy metals in agricultural soils threatening ecological security and the quality of agricultural products, and apportion their sources accurately is still a challenging task. Multivariate statistical analysis, GIS mapping, Pb isotopic ratio analysis (IRA), and positive matrix factorization (PMF) were integrated to apportion the potential sources of heavy metal(loid)s of orchard soil in Karst-regions. Study region soils were moderately contaminated by Cd. Obvious enrichment and moderate contamination level of Cd were found in study region surface soils, followed by As, Zn, and Pb. Correlation analysis (CA) and principal component analysis (PCA) indicated Ba, Co, Cr, Ni, V were mainly from natural sources, while As, Cd, Cu, Pb, Zn were derived from two kinds of anthropogenic sources. Based on Pb isotope composition, atmospheric deposition and livestock manure were the main sources of soil Pb accumulation. Further source identification and quantification results with PMF model and GIS mapping revealed that soil parent materials (46.44%) accounted for largest contribution to the soil heavy metal(loid)s, followed by fertilizer application (31.37%) and mixed source (industrial activity and manure, 22.19%). Uncertainty analysis indicated that the three-factors solution of PMF model was an optimal explanation and the heavy metal(loid) with lower percentage contributions had higher uncertainty. This study results can help to illustrate the sources of heavy metals more accurately in orchard agricultural soils with a clear expected future for further applications.

Monitoring of heavy metals in agricultural soils of the Republic of Khakasia

The production of environmentally friendly, safe food is one of the conditions contributing to the sustainable development of rural areas. Special attention is paid to the measures aimed to prevent the ingress and accumulation of heavy metal ions in agricultural products. Most researchers deal with the content of gross forms of heavy metals in agricultural soils, while it is the mobile forms that have a significant effect on their “transition” into production and accumulation. The article presents the results of studies on the content of mobile forms of cadmium, lead and copper in agricultural soils in different landscape and climatic zones of the Republic of Khakassia. It was found that the average values of concentrations of the mobile forms of heavy metals in the humus layer are within the maximum permissible concentrations. The content of lead varies from 0.3 to 2.2 mg / kg, copper - from 0.18 to 0.4 mg / kg, cadmium - from 0.01 to 0.2 mg / kg. The content of mobile forms of cadmium, lead and copper varies from year to year. During the monitoring, the oscillatory dynamics of changes in the concentration of heavy metals in the soil was revealed. The ratio of mobile forms of heavy metals (Pb: Cu: Cd) decreases in the following sequence: chestnut soils → southern chernozems → ordinary and leached chernozems → gray forest and soddy-podzolic soils.

Application of remediation treatment to reduce lead in the soil of shallot cropping

One of the pollutants on agricultural land is lead (Pb). Remediation is an effort to reduce contamination of heavy metals in agricultural soils. This study aimed to determine lead content in the soil through remediation with plus treatment. The study conducted at screen house on a pot scale using a completely randomized design with three replications and nine treatments, i.e. control/without organic fertilizer (P0), compost (P1), biochar+compost (P2), nanobiochar+compost (P3), nanobiochar+compost+consortia bacteria (P4), compost+consortia bacteria (P5), biochar+compost+consortia bacteria (P6), biochar+compost+botanical pesticide (P7) and biochar+compost+biological agents (P8). Biochar+compost (1:4) applied as basal fertilizer with dose of 2.5 t ha−1. Parameters observed were lead content in the soil at 7 DAA, 37 DAA and harvest, lead content in shallot plants (leaves and tubers) after harvest. Lead analysis used wet ashing method measured by AAS. The results showed the levels of lead metal in soil decreased from time to time except in compost treatment, while the levels of lead metal in shallots were still below of critical limit ≤ 0.5 mg kg−1. P3 treatment has potential to increase productivity while P4 and P0 could reduce lead soil higher than other treatment.

Quantitative source apportionment, risk assessment and distribution of heavy metals in agricultural soils from southern Shandong Peninsula of China

The heavy metals, including cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), zinc (Zn), and the metalloid arsenic (As) were detected in surface and core soil samples collected from a tobacco growing region in Shandong Peninsula on the east coast of China to evaluate their pollution levels, ecological and health risks, and to analyze their spatial and vertical distributions. The heavy metal sources were identified quantitatively using the positive matrix factorization (PMF) receptor model. In accordance, most of the soils did not have accumulations and were not contaminated by As, Cr, Cu, Ni, Pb, and Zn. High accumulations of Cd and Hg occurred in the soils, posing an ecological risk to the local agricultural environment, while Cr and Ni levels presented a carcinogenic health risk to humans. Four main sources of heavy metals in the soils were identified. Correspondingly Ni and Cr were mainly originated from natural sources, Hg from coal combustion, Cd from agricultural practices, Cu, Pb, and Zn from agricultural practices and industrial activities, and As from industrial activities.

Cytogenetic toxicity from pesticide and trace element mixtures in soils used for conventional and organic crops of Allium cepa L.

Pesticides and trace elements occur in complex mixtures in agroecosystems, affecting soil health and food security. Hence, it is necessary to determine their toxicity in field conditions and to develop monitoring approaches to assess conventional and organic agriculture. The aim of this research was to evaluate the associations between Allium cepa L. cytogenetic biomarkers and the realistic mixture of pesticides and trace elements found in soils of conventional, conversion, and organic crops in an intensive agricultural region in Colombia. Pesticide screening was conducted using GC-MS/MS and LC-MS/MS methods. Arsenic, cadmium, lead, and zinc were analyzed by ICP-MS; chromium, copper, nickel, and selenium by ICP-OES; and mercury by a direct analyzer. The meristematic cells in roots of Allium cepa L. were analyzed through microscopic observations to quantify cytogenetic effects. In conventional crops, 26 pesticides were detected in the soil samples, and those were below the limit of quantification in organic crops. The mean levels of As, Cd, Cr, Ni, Pb, and Se were also greater in soils of conventional crops compared to the organics. In addition, the biomarkers of cytotoxicity and genotoxicity appeared augmented in conventional samples, and those were correlated with pesticide and trace element concentrations, pollution indices, and hazard quotients. Subsequently, a discriminant function based on the mitotic index, chromosomal aberrations, and nuclear abnormalities was suitable to classify the samples by crop type. These results demonstrate the sensitivity of Allium cepa L. to the toxicity of complex mixtures in field crops and its potential as an in-situ approach for soil health monitoring in organic and conventional crop systems.

Status Assessment, Spatial Distribution and Health Risk of Heavy Metals in Agricultural Soils Around Mining-Impacted Communities in China

Status Assessment, Spatial Distribution and Health Risk of Heavy Metals in Agricultural Soils Around Mining-Impacted Communities in China

Can heavy metal pollution induce bacterial resistance to heavy metals and antibiotics in soils from an ancient land-mine?

Microbial resistance to antibiotics is a growing challenge to human health. Recent evidence has indicated that antibiotic resistance can be co-selected for by exposure to heavy metals in agricultural soils. It remains unknown if this is a concern in other environments contaminated by metals. We here investigated soil microbial activities, composition and tolerance to heavy metals and antibiotics in a mining soil survey. We found that microbial respiration, growth, and biomass were affected by available metal concentrations. Most of the variation in microbial PLFA composition was explained by differences in heavy metal and pH. Additionally, pollution-induced bacterial community tolerance to toxicants including Cu, Pb, Zn, tetracycline and vancomycin was determined. Although only bacterial tolerance to Pb increased with higher levels of metals, the links between bacterial metal tolerance and soil metal concentrations were clear when considered together with previously published reports, suggesting that bacterial metal tolerance were universally elevated in the surveyed soils. The induced levels of heavy metal tolerance coincided with elevated levels of tolerance to vancomycin, but not to tetracycline. Our study showed that heavy metals can co-select for resistance to clinically important antibiotics also in ecosystems without manure input or antibiotic pollution.

Biochar as a potential soil remediation agent for heavy metals in agriculture

Biochar is one of the most concerned research hotspots at present, which is a stable and carbon-rich solid produced by pyrolysis of organic biomass under anoxic conditions. Biochar has abundant pore structure, functional groups, aromatic hydrocarbons and other characteristics, which enable it to improve soil physical and chemical properties, increase nutrient content, and regulate soil microbial community structure. In recent years, with the continuous research on biochar, the role of biochar in the remediation of heavy metal pollution has been further studied. The physical adsorption, ion exchange, electrostatic attraction, complexation reaction, mineral precipitation, redox and other functions of biochar are the main factors for repairing heavy metal ions. In addition, immobilization is the primary goal of biochar remediation of heavy metals in agricultural soils, because it can greatly reduce the risk of human health caused by heavy metals entering the food chain. This paper reviewed the current knowledge of biochar and its function in agricultural heavy metal soil. Based on the background of heavy metal pollution in agricultural soil in China, the possible remediation mechanism of biochar was discussed. It provides scientific basis for the development and application of biochar in the remediation of heavy metal pollution in agricultural soil in China.

Biochar as a potential soil remediation agent for heavy metals in agriculture

Biochar is one of the most concerned research hotspots at present, which is a stable and carbon-rich solid produced by pyrolysis of organic biomass under anoxic conditions. Biochar has abundant pore structure, functional groups, aromatic hydrocarbons and other characteristics, which enable it to improve soil physical and chemical properties, increase nutrient content, and regulate soil microbial community structure. In recent years, with the continuous research on biochar, the role of biochar in the remediation of heavy metal pollution has been further studied. The physical adsorption, ion exchange, electrostatic attraction, complexation reaction, mineral precipitation, redox and other functions of biochar are the main factors for repairing heavy metal ions. In addition, immobilization is the primary goal of biochar remediation of heavy metals in agricultural soils, because it can greatly reduce the risk of human health caused by heavy metals entering the food chain. This paper reviewed the current knowledge of biochar and its function in agricultural heavy metal soil. Based on the background of heavy metal pollution in agricultural soil in China, the possible remediation mechanism of biochar was discussed. It provides scientific basis for the development and application of biochar in the remediation of heavy metal pollution in agricultural soil in China.

Accumulation of Toxic and Trace Metals in Agricultural Soil: A Review of Source and Chemistry in Ethiopia

The main aim of this paper review is to know the extent of toxic and trace metals in some listed part Ethiopian farmland soil and its cause. Heavy metals are persistent in the agricultural soils (environments), they are non -termly and biological degradable. Among those toxic heavy metals, Pb, Cd, As, Hg, Cr, Co, Ni, Cu, Zn, Fe, Mn, are some of them. Every year’s large amount of industrial wastes, urban wastes, automobile emission, fertilizer, pesticide, wastewater irrigation and other agricultural activities are common in large agricultural farm land of Ethiopia. Those leads in to contamination of farmland with toxic heavy metals and other pollutants, The effect of those pollutants lower the quality of products finally they affect the health of consumers. According to different reports, in Ethiopia the farmland around cities and industry zone have accumulated large amount of toxic and trace heavy metals with compared to other farmlands. Mostly the concentration of those toxic metals were above the recommended limit set by different organization like FAO, WHO, EP and other. Therefore, the concerned body should be set different strategy and rule for agricultural activities, polluted factory effluents, gasses and solid wastes and other heavy metal source in order to protect the consumers from different heavy metals caused diseases.

The benefits of biochar: Enhanced cadmium remediation, inhibited precursor production of nitrous oxide and a short-term disturbance on rhizosphere microbial community.

Biochar has the potential to remediate heavy metals in agricultural soil and mitigate nitrous oxide (N2O) emissions; however, the effects of biochar on heavy metal remediation, the soil microbial community and N2O emissions are not completely understood. In this study, we conducted a pot experiment in which Glycine max L. (soybean) was cultivated in two cadmium (Cd)-contaminated soils (low, 3.14mgkg-1; high, 10.80mgkg-1) to investigate the effects of biochar on the bioremediation of Cd, N2O emissions and the rhizosphere microbial community structure. The bioaccumulation of Cd in the plant shoots and roots increased with all biochar addition rates (0%, 1%, 5% and 10%); unexpectedly, the translocation capacity of Cd to the edible parts of the plant significantly decreased to 0.58mgkg-1, which was close to the edible threshold (0.4mgkg-1). The abundance and activities of functional marker genes of microbial nitrification (amoA) and denitrification (nirK, nirS and nosZ) were quantified with quantitative PCR, and we found that biochar addition reduced the precursor production of rhizoshpere N2O by inhibiting the transcription of the nirK gene. In addition, the nitrogenase activity during anthesis (S) was significantly (P<0.05) increased with 1% (v/v) biochar addition. Noticeably, biochar addition only changed the microbial community structure in the very first stage before eventually stabilize. This study highlighted that biochar has the potential ability to maintain the quality of agricultural crops, remediate Cd-contaminated soils and may help reduce N2O emissions without disturbing the microbial community.

Typical sources of Cd to paddy fields in different contaminated areas and their impacts on Cd accumulation in topsoil and rice in Changzhutan, China

Heavy metal pollution of soils has been worsening increasingly in China, which brings significant health risk to human, it is critical to investigate the sources of heavy metals in agricultural soils and explore the effects of heavy metal accumulation in crops. In this paper, the sources of cadmium (Cd) and their effects on Cd accumulation in soil and rice grown on urban farmland in Changzhutan were investigated. Among the main Cd sources (irrigation water, commercial fertilizer, and atmospheric deposition), the input flux of atmospheric deposition accounted for 76.36%–98.25% of total input flux, significantly higher than the input fluxes of irrigation water and commercial fertilizer. Manure fertilizer was also an important source of Cd in livestock breeding areas. The accumulation behaviors of Cd in soils and plants presented significant spatial variation among the study areas. Higher Cd input flux from atmospheric deposition resulted in higher Cd bioavailability in soil and more Cd accumulation in rice, and the newly deposited Cd contributed 7.35–41.23% in rice tissues. The use of manure fertilizer increased the soil pH and amount of available Cd in soil, as well as the accumulation of Cd in rice roots. Based on sequential extraction, acid-extractable Cd accounted for approximately 52.54%–61.88% of total Cd in atmospherically deposited particles in the study area, resulting in a high proportion of acid-extractable Cd in soil. This study provides useful reference data on the sources of Cd and its bioavailability in soil and rice.

Heavy Metals in Agriculture Soils from High Andean Zones and Potential Ecological Risk Assessment in Peru's Central Andes

Heavy Metals in Agriculture Soils from High Andean Zones and Potential Ecological Risk Assessment in Peru's Central Andes

ENVIRONMENTAL EFFICIENCY OF PERENNIAL LEGUMES AS PRECURSORS OF WINTER WHEAT GROWN IN THE CONDITIONS OF AGRICULTURAL LAND POLLUTION WITH HEAVY METALS

The aim of the research was to study the effect of the inclusion of different types of perennial leguminous plants as winter wheat precursors in the crop rotation on the rate of accumulation of heavy metals in the soil compared to traditional winter wheat predecessors. The objectives of the research are to develop measures to reduce the accumulation of heavy metals in agricultural soils under conditions of modern crop rotation, limited by the number of crops grown and winter wheat. The accumulations of heavy metals in soils were calculated during the cultivation of the main crops of crop rotation with intensive fertilizer. The concentration of heavy metals in the soil was determined before and after the cultivation of legume precursors. Field studies were carried out during 2013-2017. On gray podzolized medium loamy soils of the Agronomichesky Research Institute of Vinnytsia National Agrarian University. We calculated the volumes of heavy metals with optimal rates of mineral fertilizer application for the most common types of crops grown in crop rotation. Four types of perennial grasses were sown: sowing alfalfa, meadow clover, horned lamb, sainfoin and eastern goatskin. After their four years of use, winter wheat was sown. The control was the predecessors in the following sequence: winter wheat - sunflower - winter wheat - corn. Laboratory studies of the content of mobile forms of heavy metals in soil were carried out in the Vinnytsia branch of the State Center for the Protection of Soil Fertility. Analysis of soil contamination with heavy metals during fertilization of major cereals showed that the amount of mineral fertilizers is from 257 kg/ha to 571 kg/ha for ammonium nitrate, from 175 to 225 kg/ha for double superphosphate and from 58 to 75 kg/ha on potassium chloride. According to the volume of mineral fertilizers used in the cultivation of winter wheat, 1944 mg / ha of lead and 339 mg / ha of cadmium enter the soil. Of these, with ammonium nitrate - 51.4% and 7.4%, respectively, with double superphosphate - 39.6% and 41.3% and with potassium chloride - 9.0% and 51.3%. When growing corn per 1 ha with mineral fertilizers, 2357 mg of lead and 434 mg of cadmium are applied, of which with ammonium nitrate - 48.4% and 6.7%, respectively, with double superphosphate - 42% and 41% and with potassium chloride. - 9.6% and 51.8%. Cultivation of spring barley leads to the receipt of mineral fertilizers to soils 1458 mg/ha of lead and 327 mg/ha of cadmium, of which with ammonium nitrate - respectively 35.2% and 4.0%, with double superphosphate - 52.8% and 42.8% and with potassium chloride - 12.0% and 53.2%. Mineral fertilization of winter rape leads to the entry into the soil per 1 ha of 2223 mg of lead and 390 mg of cadmium, of which with ammonium nitrate - respectively 51.4% and 7.4%, with double superphosphate - 39.6% and 41% and with potassium chloride - 9.0% and 51.5%. With mineral fertilizers for growing sunflower in the soil per 1 ha gets 2073 mg of lead and 427 mg of cadmium, of which with ammonium nitrate - respectively 41.4% and 5.2%, double superphosphate - 47.8% and 42.2 % and potassium chloride - 10.8% and 52.6%. The positive effect of growing leguminous perennial herbs on the decrease in the concentration of heavy metals in the soil and grain of winter wheat has been established. Under the conditions of intensive farming by Vinnitskaya, lead and cadmium fall into the soil for the use of mineral fertilizers in accordance with 1944 mg/ha and 339 mg/ha for growing winter wheat, 2357 mg/ha and 434 mg/ha for growing corn, 1458 mg/ha and 327 mg/ha when growing spring barley, 2223 mg/ha and 390 mg/ha when growing sunflower. The four-year cultivation of perennial leguminous grasses under intensive farming reduced the concentration of lead in the soil from 1.33 to 3.2 times and cadmium from 37 to 54 times compared with cereal crops, which contributed to improving the quality of winter wheat grain by reducing the concentration of lead from 1 7 to 2.4 times and cadmium from 1.4 times to 2.1 times. Key words: legumes, precursors, winter wheat, heavy metals, pollution.

Occurrence and ecological risk assessment of heavy metals in agricultural soils of Lake Chilwa catchment in Malawi, Southern Africa

Understanding the levels and associated ecological risk caused by heavy metals is important for the sustainable management and utilization of Lake Chilwa catchment, an important ecosystem in Malawi providing fertile lands for agriculture and a designated wetland ratified by the Ramsar convention in 1997. Concentrations of chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), arsenic (As), mercury (Hg) and cadmium (Cd) were analyzed from 22 soil sampling locations. Extraction and quantification were achieved by microwave digestion and Inductively Coupled Plasma Optical Emission Spectrometer, respectively. Mean values were detected in the following order; Zn > Cr > Ni > Cu > Pb > As. Strong correlations were observed between As and Pb (r = 0.85), Cr and Ni (r = 0.82), Cu and Ni (r = 0.81), Cr and Cu (r = 0.8), and Pb and Zn (r = 0.73) suggesting similar sources of input. Principal component analysis revealed that Cu, Pb, Zn and As originate from anthropogenic activities, while Cr and Ni were geogenic. The ecological risk caused by these metals, calculated by the Ecological Risk Index (RI) method, showed a low to moderate ecological risk. The wetland areas had higher overall concentrations and RI values compared to the rest of the catchment. It is therefore important to enforce measures to manage and control these levels to avoid their damaging effects.

Spatial distribution, pollution, and health risk assessment of heavy metal in agricultural surface soil for the Guangzhou-Foshan urban zone, South China.

During the past decades, heavy metal pollution in agricultural soil and its impact on human health have been becoming one of the most important global environmental problems. In this research, heavy metal (Cu, Pb, Zn, Cr, Cd, Ni, As, Hg) concentrations were measured for four hundred and two soil samples collected from agricultural area within the Guangzhou-Foshan urban zone. Soil heavy metal pollution was evaluated used geoaccumulation index and potential ecological risk index. The dose response model proposed by the USEPA was used to estimate the potential health risk caused by heavy metals in agricultural soil. The results showed that: 1) Cd and Hg were the main heavy metal pollutants in agricultural soil of the study area. 89.1% and 93.3% of total soil samples suffered medium to heavy potential ecological risk caused by Cd and Hg, respectively. 2) The THI and TCR were respectively greater than 1.0 and 1.0×10-4, indicating that heavy metals in agricultural soil were likely to constitute non-carcinogenic and carcinogenic risks, both of which were mainly brought by product consumption, to the public in the study area. The non-carcinogenic risks were mainly caused by Cr and As, while the carcinogenic risks were mainly from Cr, Cd, and As.