Metal Contamination Of Agricultural Soils Research Articles

Impact of a super typhoon on heavy metal distribution, migration, availability in agricultural soils

Heavy metal contamination in agricultural soils is a worldwide concerned environmental issue. However, a short-term extreme hydrodynamic event (e.g., a super typhoon) may significantly affect the distribution, migration, and availability of heavy metals in agriculture soils on a large scale. The limited understanding of such an impact prevents effective environment survey, risk assessment, and remediation strategy for heavy metal contaminated soils. Here, we show a massive migration of heavy metals during a super typhoon (Lekima) based on the field investigation, simulated experiments, and isotopic fingerprinting. The contaminations of heavy metals (Cd, Zn, Cu, Ni, Cr and As) of agricultural soils at 209 sampling sites over 3.59 × 105 km2, were significantly relieved by 10.3–42.0 % after the typhoon, because of the primary contribution of runoff erosion over interflow according to the simulated soil erosions. However, the available fractions (as % of the total amount of each metal) were metal-dependent, with Cd, Zn, Cu, and Ni increased (5.3–26.4 %), and Cr and As decreased (0.9–3.5 %). In contrary, the Pb contamination was slightly aggravated by 8.7 % after the typhoon, and the Pb isotopic signatures indicate its input and migration via wet precipitation and surface runoff. The soil properties (e.g., pH and organic matter) showed limited impact on the migration of heavy metals during this typhoon. These results suggest that a natural short-term extreme hydrodynamic event can drive the massive migration of heavy metals in agricultural soils and their trade-off with other environmental medias, providing valuable information for multi-medias environmental risk assessment and cooperative remediation that can be significantly disturbed by such an event.

Estimation of Heavy Metals in Agricultural Soils Using Vis-NIR Spectroscopy with Fractional-Order Derivative and Generalized Regression Neural Network

With the development of industrialization and urbanization, heavy metal contamination in agricultural soils tends to accumulate rapidly and harm human health. Visible and near-infrared (Vis-NIR) spectroscopy provides the feasibility of fast monitoring of the variation of heavy metals. This study explored the potential of fractional-order derivative (FOD), the optimal band combination algorithm and different mathematical models in estimating soil heavy metals with Vis-NIR spectroscopy. A total of 80 soil samples were collected from an agriculture area in Suzi river basin, Liaoning Province, China. The spectra for mercury (Hg), chromium (Cr), and copper (Cu) of the samples were obtained in the laboratory. For spectral preprocessing, FODs were allowed to vary from 0 to 2 with an increment of 0.2 at each step, and the optimal band combination algorithm was applied to the spectra after FOD. Then, four mathematical models, namely, partial least squares regression (PLSR), adaptive neural fuzzy inference system (ANFIS), random forest (RF) and generalized regression neural network (GRNN), were used to estimate the concentration of Hg, Cr and Cu. Results showed that high-order FOD had an excellent effect in highlighting hidden information and separating minor absorbing peaks, and the optimal band combination algorithm could remove the influence of spectral noise caused by high-order FOD. The incorporation of the optimal band combination algorithm and FOD is able to further mine spectral information. Furthermore, GRNN made an obvious improvement to the estimation accuracy of all studied heavy metals compared to ANFIS, PLSR, and RF. In summary, our results provided more feasibility for the rapid estimation of Hg, Cr, Cu and other heavy metal pollution areas in agricultural soils.

Effect of chromium on basic growth factors of Pennisetum glaucum L.

One of the main concerns of agricultural production is heavy metal pollutants. The industrialization has resulted in the heavy metal contamination of agricultural soil and ecosystems. Metals are a natural component of the earth, it is when their concentration increases from natural levels, ecological deterioration occurs. In the present study, transplant experiments were conducted to evaluate the effect of chromium-contaminated soil in Pennisetum glaucum L. The seeds growing in petridishes were exposed to chromium, in increasing concentrations of 1, 3, 5, 10, 50, 100, 200, 300, 500 ppm. Each treatment was replicated in a randomized design and observed over a period of 7 days. The seedlings were studied for their response based on germination rate, seed vigour index, length of the radicle, length of plumule, and fresh weight against seeds germinated using distilled water as a control. Five different chromium concentrations i.e., 5, 10, 50, 100 & 200 ppm, were applied to the plants. Each treatment was replicated in a randomized design and observed for 45 days. The plants were studied for the length of root, length of shoot, fresh weight, total chlorophyll content, protein content, and heavy metal analysis compared to a set irrigated using distilled water as a control. The root and shoot lengths decreased with an increase in Cr concentrations in the transplants. A gradual decrease was observed in the selected parameters, with an increase in Cr levels. The values related well with increased Phyto-accumulation of chromium within the tissues of both roots and shoots. It was observed that chromium's harmful effects on all the parameters were directly proportional to the concentration of solution employed, with the inhibition of growth being more pronounced from 50 ppm onwards. As Pennisetum glaucum L. an edible crop despite showing a good potential for application in phytoremediation techniques, it can’t be used to hyper accumulate chromium to remove it from the soil.

Spatial Assessment of Heavy Metal Contamination in Agricultural Soils Developed on Basaltic and Sandstone Parent Materials

Spatial Assessment of Heavy Metal Contamination in Agricultural Soils Developed on Basaltic and Sandstone Parent Materials

Features of Heavy Metal Contamination of Agricultural Soils in the Kursk Region of Russia and Economic Assessment of Restoration

Kursk region of Russia has unique fertile soils. Heavy metals are among the factors that pollute the soil. The article is devoted to the study of the spatial distribution of heavy metals in soils. The relevance of the study is that the value of the soil is determined by its value for obtaining environmentally friendly agricultural products. Data on the content of heavy metals in the soil can prevent intensive cultivation of crops. The task of the work is to identify heavy metals that predominate in the soils of various landscapes of the Kursk region. The assessment of soil contamination with chemical elements was carried out in the course of geo-ecological studies of black earth soils in the Kursk region of Russia. The selected soil samples were examined by semi-quantitative spectral analysis. The results obtained were subjected to statistical processing. It was found that cobalt is the main pollutant in the vast majority of sampling points. In other zones, molybdenum, lead, zinc, and chromium predominate in approximately equal amounts. Soils in the surveyed area belong to the permissible category of contamination with chemical elements. Soil remediation should be applied in local areas.

Metal contamination of agricultural soils amended with biosolids (sewage sludge) at a ceramic production area in NE Spain: A 10‐year resampling period

AbstractHeavy metals in ecosystems affect human health through the web chain. Castellon Province is home to the largest ceramic production hub in Spain, with 94% of the country's total production. Agricultural soils in the vicinity of the ceramic hub were reported to contain potentially toxic elements (Pb, Cr, Ni and Cd) in 2008 and have since been subject to repeated amendment with biosolids (sewage sludge). The sample sites were revisited in 2019, and the chemical distribution of these metals reassessed. The distribution of heavy chemical forms was analysed using a sequential extraction protocol that fractionates these four heavy metals into five phases. The incorporation of biosolids for the past 10 years has changed the chemistry of the soil, leading to increased levels of some hazardous elements. The carbonate‐sorbed, residual and reducible phases were dominant. From the point of view of compliance with regulations, levels of Cd remained elevated and have increased over the 10‐year period.

Dose-dependent Effect of Biochar as Soil Amendment on Reducing Copper Phytotoxicity and Mobility

Using biochar to remediate metal-contaminated agricultural soil has attracted increasing attention due to it is relatively low cost and high efficiency. In this study chemical speciation, greenhouse experiments, and column leaching study were conducted to understand the mechanisms of copper (Cu) immobilization by pine needle biochar (PNB) and sweet potato residue biochar (SPRB) to evaluate the effect of biochar amendment rate for remediation Cu contaminated soils. The results showed that both PNB and SPRB amendment effectively raised soil pH and converted Cu into more stable chemical forms. 1% (W/W) SPRB was adequate for reducing exchangeable Cu fractions from 43.3 to 9.9 mg kg−1 in the contaminated soils. 1% (W/W) SPRB and 5% (W/W) PNB treatments show the best result to promote sweet potato growth. Over liming caused by 5% (W/W) SPRB resulted in inhibition of plant growth. 5% (W/W) PNB treatment also shows the best result for reducing Cu mobility: the cumulative amount of Cu in the leachate after 9 leaching events was reduced from 7.0 to 1.0 mg kg−1. However, 5% (W/W) SPRB amendment is a little effective for reducing Cu mobility. Although the biochar amendment can provide additional sorption sites for metal pollution remediation, soil pH after an amendment is also a critical factor to estimate optimal biochar application dosage for promoting plant growth and reduce metal leachability.

Enrichment, sources and ecological risk mapping of heavy metals in agricultural soils of dhaka district employing SOM, PMF and GIS methods

Rapid urbanization and industrial growth have triggered heavy metal contamination in agricultural soil in Dhaka, which is a serious concern for ecological risk and public health issues. In this study, fifty-four soil samples from agricultural lands of Dhaka had been analyzed for assessing accumulation, spatial enrichment, ecological risk and sources apportionment of heavy metals using a combined approach of self-organizing map (SOM), positive matrix factorization (PMF), geographical information system (GIS), and enrichment factor (EF). The results of the enrichment factor, geoaccumulation index and contamination factor index showed that more than 90% of the soil samples were polluted by higher levels of Cr and Cd. The mean pollution load index (PLI) results demonstrated that about 73% of soil samples were moderately polluted by heavy metals. Based on SOM and PMF analysis, four potential sources of heavy metals were found in this study area: (i) agrochemical and sewage irrigation (Cd–As); (ii) combined effect of agriculture, industrial and natural sources (Mn, Co, Ni and Zn); (iii) atmospheric deposition and industrial emission (As–Pb); (iv) chemical and leather tanning industries (Cr). The ecological risk index demonstrated that in terms of Cd content, about 75% of soil samples were moderate to high risk, and 20% were moderate to considerable ecological risk, which was the serious environmental, ecological, and public health concern. The spatial projection of ecological risk values showed that the southern part of Dhaka (Keraniganj Upazila) is a high ecological risk in terms of heavy metal pollution. These risk maps in agricultural soils may play a vital role in reducing pollution sources; so that zonal pollution control, as well as ecological protection, may be achieved in this resource-based agricultural land.

Zinc tolerant plant growth promoting bacteria alleviates phytotoxic effects of zinc on maize through zinc immobilization

The increasing heavy metal contamination in agricultural soils has become a serious concern across the globe. The present study envisages developing microbial inoculant approach for agriculture in Zn contaminated soils. Potential zinc tolerant bacteria (ZTB) were isolated from zinc (Zn) contaminated soils of southern Rajasthan, India. Isolates were further screened based on their efficiency towards Zn tolerance and plant growth promoting activities. Four strains viz. ZTB15, ZTB24, ZTB28 and ZTB29 exhibited high degree of tolerance to Zn up to 62.5 mM. The Zn accumulation by these bacterial strains was also evidenced by AAS and SEM–EDS studies. Assessment of various plant growth promotion traits viz., IAA, GA3, NH3, HCN, siderophores, ACC deaminase, phytase production and P, K, Si solubilization studies revealed that these ZTB strains may serve as an efficient plant growth promoter under in vitro conditions. Gluconic acid secreted by ZTB strains owing to mineral solubilization was therefore confirmed using high performance liquid chromatography. A pot experiment under Zn stress conditions was performed using maize (Zea mays) variety (FEM-2) as a test crop. Zn toxicity reduced various plant growth parameters; however, inoculation of ZTB strains alleviated the Zn toxicity and enhanced the plant growth parameters. The effects of Zn stress on antioxidant enzyme activities in maize under in vitro conditions were also investigated. An increase in superoxide dismutase, peroxidase, phenylalanine ammonia lyase, catalase and polyphenol oxidase activity was observed on inoculation of ZTB strains. Further, ZIP gene expression studies revealed high expression in the ZIP metal transporter genes which were declined in the ZTB treated maize plantlets. The findings from the present study revealed that ZTB could play an important role in bioremediation in Zn contaminated soils.

Heavy metal contamination in agricultural soil and ecological risk assessment in the northeast area of Tadla plain, Morocco

The present study investigated the potentially toxic heavy metal (Cu, Pb, Zn, Cr, and Cd) contamination and its ecological impact in the agricultural soil in the northeast part of Tadla plain (Morocco). A total of 60 subsurface composite samples were collected and analyzed to determine pH, soil organic matter (SOM) and texture, and heavy metal concentrations. Pollution levels were assessed by adopting enrichment factor (ef), geoaccumulation index (Igeo), contamination factor (CF), pollution load index (PLI), and ecological risk index (RI). The results showed that the average concentrations of Cd, Cr, Cu, Pb, and Zn in the collected 60 topsoil samples were 0.92, 32.72, 138.10, 31.72, and 162.11 mg/kg, respectively, and followed the order Zn > Cu > Cr > Pb > Cd. These concentrations exceeded acceptable thresholds of the World Health Organization (WHO) and Food and Agriculture Organization (FAO) and local background. From the Principal Component Analysis (PCA) results showing no correlation between the soil properties and heavy metal contents, suggesting that the metal elements were of different sources, especially anthropogenic. The mean RI values of 65.68 indicated a low ecological risk and indicate that the study area is moderately to strongly pollute in the case of Zn and Cu and partly influenced by human activities. Nevertheless, this study provided important information for policymakers to propose an appropriate plan for pollution control in the agricultural Tadla plain.

Heavy Metal Contamination in Agricultural Soil, Food Crops and Associated Gastric Cancers Risks for Residents in S County of Hebei Province

Because of the anatomic location of stomach and its acid environment which is different from the other organs, food exposure to heavy metals is a well-known risk factor for human gastric cancers. To evaluate the potential risks, we analyzed the concentrations of heavy metals (Cr, Cd, Pb, and As) in agricultural soil and grains in a high incidence area of gastric cancer, S county of Hebei province. Potential carcinogenic risk index for heavy metals in grains were evaluated. The results indicate that the concentrations of Cr, Cd, Pb and As in soils were 36.44, 0.13, 28.01 and 13.72 mg/kg, respectively; and 2.372, 0.051, 0.494 and 0.026 mg/kg in grains, respectively. The potential carcinogenic risk index of Cr, Pb and As in grain exceeded the safety limit level of 10−4 and Cd exceeded the acceptable limit level of 10−6. Therefore, long-term low dose exposure of heavy metals may play an important role in tumorigenesis of human gastric cancers.

Contamination characteristics, source apportionment, and health risk assessment of heavy metals in agricultural soil in the Hexi Corridor

To determine the heavy metal contamination of agricultural soil in the Hexi Corridor, 376 soil samples were collected and analyzed for their heavy metal content. The geochemical baseline value (GBV), single-factor pollution index (PI), ecological risk of a single heavy metal, and comprehensive ecological risk index (RI) were used to assess the degree of pollution. Geostatistical analysis, positive matrix factorization (PMF), and a health risk assessment model were used to determine the primary sources of pollution and priority sources. Although the mean Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, and Pb concentrations (2717, 62.85, 48.23, 511.6, 24827, 51.29, 26.47, 53.98, 12.39, 16.85 mg•kg−1 in the west, 3046, 72.15, 59.32, 598.1, 27614, 54.57, 29.55, 59.47, 13.63, 20.74 mg•kg−1 in the center, and 2558, 61.02, 39.67, 466.7, 22575, 39.94, 26.06, 54.81, 11.86, 20.38 mg•kg−1 in the east, respectively) did not exceed the national critical values, approximately 1% of the west As samples did exceed their critical values. The mean concentrations of the heavy metals were less than their corresponding GBVs. The PI and RI revealed that the agricultural soil was moderately polluted, at low ecological risk, and the least polluted in the center. Based on PMF, Factor 1 represented metal processing; Factor 2 represented the mixed sources of electroplating and smelting in the west and center, and the mixed sources of mining and agricultural activities in the east; Factor 3 was ascribed to agriculture; and Factor 4 was the mixed sources of atmospheric deposition and traffic emission. The main pollution source, Factor 4 in the west and east and Factor 2 in the center, had the highest percent proportion of total metals and priority pollution sources, thus contributing the most to the carcinogenic (Factor 2 in the west and Factor 3 in the center and east) and non-carcinogenic risks (Factor 2 for adults and Factor 1 for children in the west and Factor 3 in the center and east), respectively.

Analysis of Heavy Metal Contamination of Agricultural Soils and Related Effect on Population Health-A Case Study for East River Basin in China.

To understand the heavy metal pollution in agricultural soils along the East River basin and assess the pollution related health effect to local residents, interviews and archived data were obtained to identify the study sites affected by polluted tailing. Soil samples were collected and tested for heavy metal content and the Comprehensive Pollution Index (CPI). The degree of pollution of agricultural soils in the area was assessed using GIS-based Spatial distribution map of heavy metals and the trend of soil heavy metal risk. Two villages (Matian and Zhudui) near the East River were included in this study for health effect assessment. A total of 193 residents aged 15 or above from each village were tested for the present status of chronic diseases. Convenient sampling method was used to collect blood samples from 78 residents for heavy metal concentration. The contents of Pb, Cd, As, Zn, and Cu in the agricultural soils were all over the standards with a moderate to severe CPI. Among these metals, Cd was the highest followed by Pb, and Cu was the lowest. The contents of Pb, Cd, As, and Zn tend to be higher in soils closer to the river. The prevalence of chronic diseases was over 30%, which is significantly higher than the report from the national central region (23.15%). The average blood lead level (BLL) among children under 14 years is 7.42 μg/dL. Although the adults in Matian village had a significantly higher BLL (χ2 = 8.70, p = 0.03) as compared to Zhudui village, there was no significant difference for the prevalence of chronic diseases between the two villages (χ2 = 3.23, p = 0.09). The mean BLL of children and the proportion of children with BLL ≥ 10 µg/dL in this study are equivalent to the national average. The higher BLL concentration and prevalence of chronic diseases in adults might be due to their long-term exposure to heavy metal contamination environment and higher background level of heavy metals. Findings from this study will form the baseline information for local government to the development of effective approaches to control the heavy metal contamination and reduce the pollution related adverse health effect on local residents.

Evaluation of the environmental and human health risk related to metallic contamination in agricultural soils in the Mediterranean semi-arid area (Saiss plain, Morocco)

In the plain of Saiss, the most agricultural region of Morocco, the studies concerning the assessment of environmental and human risks related to metal contamination of agricultural soils are severely missing. To overcome the lack of such studies, trace-element analyses were carried out on six sampling sites of agricultural surface soils (66 sampling points), irrigated by superficial watercourses with high heavy metal contents. The average trace-element contents were 78, 55, 33, and 119 (mg kg−1), respectively, for Cr, Cu, Ni, and Zn. These values are above average worldwide soil and geochemical background levels. Multivariate statistical analyses, principal component, and cluster analyses suggest that soil contamination by Cr, Cu, and Zn is mainly due to wastewater irrigation, with the exception of Ni, which is probably of pedo-lithogenic origin. To provide further information on contamination transmission, the bioavailability and distribution of the four heavy metals in the soils were studied by sequential and single extractions. The results indicate that Cu and Zn are potentially available and can constitute a potential risk to the environment. The risk assessment of soil contamination was also carried out using risk assessment code, enrichment factor, contamination factor, degree of contamination, pollution lead index, geoaccumulation index, and potential ecological risk factors. The health risk evaluation by the Hazard Index was used to derive a combined risk of soil ingestion, dermal contact, and inhalation for adults and children. According to these indices, the soils present a moderate-to-high contamination for Cu and Zn elements, respectively. Hazard Index values indicate the relative absence of health risks associated to heavy metals for both adults and children.

Assessment of human health risks and pollution index for heavy metals in farmlands irrigated by effluents of stabilization ponds.

Areas contaminated with heavy metals can pose major risks to human health and ecological environments. The aims of this study are to assess human health risk and pollution index for heavy metals in agricultural soils irrigated by effluents of stabilization ponds in Birjand, Iran. The results revealed that the levels of Cr, Mn, Zn, Fe, Cu, Cd, and Pb were in range of 70.3-149.65, 355-570, 31.15-98.45, 23,925-29,140, 22.75-25.95, 0.17-6.51, and 8.5-23.5mg/kg in topsoils, respectively. Total hazard index values from heavy metals through three exposure routes for adults and children were 9.13E-01 and 1.10, respectively, indicating that there was non-carcinogenic risk for children. The total risk of carcinogenic metals (Cr, Cd, and Pb) through the three exposure routes for adults and children was 1.06E-04 and 9.76E-04, respectively, which indicates that the metals in the soil will not induce carcinogenic risks to these age groups. Pollution levels of heavy metals in soil samples including enrichment factor (EF), contamination factor (CF), pollution load index (PLI), and geo-accumulation index (Igeo) showed heavy metal contamination of agricultural soils. The results of the present study provide basic information about heavy metal contamination control and human health risk assessment management in the study area.

Accumulation and bioavailability of heavy metals in an acid soil and their uptake by paddy rice under continuous application of chicken and swine manure

Heavy metal contamination of agricultural soils is a global concern, as it can cause the accumulation of heavy metals in food. In this study, a field experiment was carried out to investigate the effect of the continuous application of chicken or swine manure on the Pb, Cd, Cr and As bioavailability, fractionation, and accumulation in soil and uptake by rice plants. Results showed that chicken or swine manure significantly reduced the Cd and Pb contents in rice grain by 7.8–79.3% and 7.2–59.4%, respectively, with increasing application rates and number of years; the exchangeable Cd and Pb fractions, and the diethylenetriaminepentaacetic acid (DTPA)-extractable Cd and Pb in the soil were also decreased. Furthermore, the application of chicken or swine manure substantially increased the DTPA-extractable As and exchangeable As fractions in the soil but had limited effect on As accumulation in rice grain. No significant differences in the bioavailability in soil nor accumulation in the rice grain were found for Cr between the treatments. Therefore, livestock manure can be used as soil amendments to decrease Cd and Pb accumulation in rice grains, nevertheless, the potential risk of metal accumulation in soils caused by livestock manure application should be considered.

Isolation of Cadmium and Lead Tolerant Plant Growth Promoting Rhizobacteria: Lysinibacillus varians and Pseudomonas putida from Indian Agricultural Soil

ABSTRACTCadmium and lead tolerant plant growth promoting rhizobacteria can be an eco-friendly option for reclamation of metal-contaminated soil and mitigation of heavy metal stress for phytostimulation to develop sustainable agriculture. Novel heavy metal tolerant PGPR strain isolation is prerequisite in practical scale. The present study was to isolate, characterize and identify cadmium and lead tolerant PGPR strains. Some potent multi heavy metal tolerant PGPRs were isolated from rhizospheric soil contaminated with industrial, sewage or agrochemical waste and two most promising strains were identified as Lysinibacillus varians strain KUBM17 and Pseudomonas putida strain KUBM18 on the basis of 16S rDNA sequencing. These two strains were exhibiting a high degree of Cd and Pb tolerant ability with bioaccumulatory properties to remove Cd and Pb from the medium which was evidenced by AAS study. Furthermore, L. varians strain KUBM17 and P. putida strain KUBM18 showed very promising PGP traits such as ammonia production, IAA production (20–22 µg/ml), Nitrogen fixation, phosphate solubilization (55–515 ppm) and siderophore production (14–40 nmole) capability together with biocontrol properties with survival ability under different agro-climatic conditions. These PGPR isolates improved the early radish plant growth under cadmium and lead stress condition. So, KUBM 17 and KUBM 18 might be concerned as PGPR-biofertilizer in heavy metal-contaminated agricultural soil.

Rapid and Simultaneous Detection of Hazardous Heavy Metals Contamination in Agricultural Soil Using Infrared Reflectance Spectroscopy

Soil function can be disrupted by highly accumulated contaminations in soils, due to several human activities such as building construction, mining, sewage disposal, transportation, and fertilizing. These activities may cause contaminations especially by heavy metals accumulated in soil and surely will affects growing plants on it. A real time, quick, robust and simultaneous method is therefore required to rapidly detect heavy metal contamination in agricultural soil. Infrared technology has been widely employed and applied in many field areas including in agriculture and soil science. The main aim of this research is to study the feasibility of infrared spectroscopy as a fast and robust method in detecting hazardous contaminations caused by accumulated heavy metals namely Zn and Pb in agricultural soil. Diffuse reflectance spectral data were acquired for a total of 8 soil samples from four different site locations in Aceh province. Spectra data, in wavelength range of 1000-2500 nm, were enhanced using multiplicative scatter correction (MSC). Hazardous detection was performed using principal component analysis (PCA) and accumulated heavy metals were predicted using partial least square regression (PLSR) method. The results showed that IR spectroscopy can clearly distinguish contaminated soil and un-contaminated ones, with total explained variance derived from PCA was 97%. Both accumulated heavy metals (Zn and Pb) can be predicted simultaneously with coefficient correlation (r) were 0.98 for Zn and 0.98 for Pb, whereas residual predictive deviation (RPD) indexed were 3.85 for Zn and 3.91 for Pb. It may conclude that infrared spectroscopy can be used as a fast, robust and accurate method in detecting and predicting heavy metal contaminations in agricultural soil.

Soil treatment and crop rotation for in situ remediation of heavy metal-contaminated agricultural soil in gold mining areas

In many areas of China, agricultural land is subject to heavy metal contamination from mining activity. This study investigates an in situ remediation program suitable for the recovery of heavy metal-contaminated agricultural soil around mining areas. A 1-year field experiment was conducted in a gold mining area of Tongguan, Shaanxi Province, China, to evaluate the effectiveness of engineering remediation measures, including adding a layer of noncontaminated soil, or soil homogenization to 40 cm and 80 cm depths, and three crop rotation systems, including rye-corn rotation, wheat-corn rotation, and potato-adzuki bean rotation on ameliorating heavy metal pollutants from contaminated agricultural soil around mining areas. The results showed that soil treatment and crop rotation significantly decreased soil heavy metal concentrations, with 80 cm homogenization and wheat-corn rotation being most effective. After 1 year of in situ remediation using this combination, the concentrations of Hg, Cd, and Pb in topsoil (0–20 cm) were 71.7%, 82.4%, and 21.8% lower, respectively, than before remediation. The single and Nemero indexes of the edible parts of wheat and corn were both <1, indicating they were safe for consumption. The results provide a solution for the in situ remediation of heavy metal-contaminated agricultural soil in mining areas.

Bioavailability of mercury in contaminated soils assessed by the diffusive gradient in thin film technique in relation to uptake by Miscanthus × giganteus.

We assessed the relationship between the diffusive gradient in thin film (DGT) technique using the new ion-exchange resin Ambersep GT74 and the uptake of mercury (Hg) by a model plant cultivated on metal-contaminated agricultural soils under greenhouse conditions. Based on the total Hg content, 0.37 to 1.17% of the Hg passed to the soil porewater from the solid phase, and 2.18 to 9.18% of the Hg is DGT-available. These results were confirmed by calculating the R value (the ratio of the concentrations of bioavailable Hg measured by DGT and soil solution), which illustrated the strong bonding of Hg to the solid phase of soil and its extremely low mobility. Only inorganic Hg2+ species were found in the metal-contaminated agricultural soils, as determined by a high-performance liquid chromatography-cold vapor atomic fluorescence spectrometry speciation analysis. The Hg was distributed in Miscanthus × giganteus organs in the following order for all sampling sites: roots (55-82%) >> leaves (8-27%) > stems (7-16%) > rhizomes (4-7%). Environ Toxicol Chem 2019;38:321-328. © 2018 SETAC.