Soil Pb Concentrations Research Articles

Comprehensive assessment of heavy metal risk in soil-crop systems along the Yangtze River in Nanjing, Southeast China.

Conventional assessment of soil environmental quality commonly focuses on soil heavy metals (HMs), neglecting the HMs in agricultural products. To response this shortcoming, a comprehensive assessment combining both soil environmental quality and agricultural product security for evaluating soil HM impact is urgently required. This comprehensive assessment incorporates not only the HM contents in soil and agricultural product but also soil environmental quality standards, soil elemental background values, and safety standards for HMs in agricultural products. In this study, it was applied to evaluate the potential risk of HMs in soil-crop systems (i.e., soil-vegetable, soil-maize, soil-rice, and soil-wheat systems) along the Yangtze River in Nanjing, Jiangsu Province, Southeast China. Furthermore, 114Cd/110Cd isotope ratio analysis was used to identify the specific contamination sources. The mean concentrations of Cd, As, Hg, Pb, Cu, Zn, and Cr in the surface soils (0-20cm) were 0.26, 11.07, 0.09, 32.63, 38.57, and 107.92mgkg-1, respectively, exceeding the corresponding soil background values. Fertilizer and atmospheric deposition were the major anthropogenic sources of HM contamination in crop-growing soils. In addition to the crop type, soil pH and organic matter also influenced the transfer of HMs from soils to the edible parts of crops. Results of comprehensive assessment revealed that approximately 11.1% of paired soil-crop sites were multi-contaminated by HMs, among which paddy soils had the highest potential risk of HMs followed by maize soils, vegetable soils, and wheat soils. To evaluate the potential risk of HMs in arable land, this study provides a novel, scientific and reliable approach via integrating soil environmental quality and agricultural product security.

Geostatistical Tools to Assess Existing Monitoring Network of Forest Soils in a Mountainous National Park

Environmental changes in national parks are generally subject to constant observation. A particular case is parks located in mountains, which are more vulnerable to climate change and the binding of pollutants in mountain ranges as orographic barriers. The effectiveness of forest soil monitoring networks based on a systematic grid with a predetermined density has not been analysed so far. This study’s analysis was conducted in the Stolowe Mountains National Park (SMNP), SW Poland, using total Pb concentration data obtained from an initial network of 403 circle plots with centroids arranged in a regular 400 × 400 m square grid. The number and distribution of monitoring plots were analysed using geostatistical tools in terms of the accuracy and correctness of soil parameters obtained from spatial distribution imaging. The analysis also aimed at reducing the number of monitoring plots taking into account the economic and logistic aspects of the monitoring investigations in order to improve sampling efficiency in subsequent studies in the SMNP. The concept of the evaluation and modification of the monitoring network presented in this paper is an original solution and included first the reduction and then the extension of plot numbers. Two variants of reduced monitoring networks, constructed using the proposed procedure, allowed us to develop the correct geostatistical models, which were characterised by a slightly worse mean standardised error (MSE) and root mean squared error (RMSE) compared to errors from the original, regular monitoring network. Based on the new geostatistical models, the prediction of Pb concentration in soils in the reduced grids changed the spatial proportions of areas in different pollution classes to a limited extent compared to the original network.

Geochemical Patterns and Source Analysis of Soil Heavy Metals in an Iron and Manganese Ore Area of Longyan City

Bedrock and soil samples from different soil profile layers were collected in an iron and manganese ore area of Longyan City and total amounts of Pb, Cd, and As were determined. The geochemical patterns of three heavy metal elements in the soil were studied using ordinary Kriging interpolation and their sources were also analyzed. High concentrations of Pb and As were found near the mining area to the west, at the intersection of two rivers in the middle, and near the waste rock heap in the east of the study area, while the main area of Cd contamination is located near to the mining areas and ore dressing plant. Based on a horizontal section, the content of Pb, Cd, and As in soils from the high-value region of each layer decreased with horizontal distance from the mining area. Vertically, the concentrations of heavy metals in different soil layers were significantly correlated. Near the mining area, Pb, Cd, and As concentrations first increased and then decreased with depth. In other high-value regions, the concentrations of these three heavy metals decreased with soil profile depth. These heavy metals inherit the characteristics of the deposit and bedrock during the weathering process, and the content of Pb and As in the soil at different depths was significantly positively correlated with granite and diorite content. Although As has been artificially influenced by mining, this influence does not appear to be strong; parent rock in the study area shows higher concentrations of heavy metals, while at the same time, the Pb and Cd content of soil is significantly higher than in the rock indicating the influence of human activities including mining, transportation, and agricultural production. Further attention should now be paid to the quality and safety of agricultural products, crop growth, and possible environmental risks in the study area.

The Soil Heavy Metals Content and Distribution of Jiujiang City

Soil pollution is serious now worldwide especially in China, with the continuous expansion of industrialization, the problem of soil heavy metal pollution is becoming more and more serious which is toxic to human beings. We studied the content and distribution of Cu, Zn, Pb, Cr, and Cd in soil of Jiujiang city. The results showed that the content of Cr and Zn were higher than others and the content of Cd was the lowest. Meanwhile, the content of the same heavy metal element has no significant difference between samples in different depth of the sampling point as our studied.

Biological Restoration of Urban Soils after De-Sealing Interventions

Most urban greening interventions involve soil de-sealing and management to enhance fertility. Management typically requires translocating fertile topsoil to the site, which comes at great environmental costs. We hypothesized that de-sealed urban soils would undergo an increase of their fertility without exogenous topsoil application. We assessed experimental plots with de-sealed soil with topsoil, and de-sealed soil without topsoil. Both treatments were vegetated with two ornamental shrub species and irrigated. Soil fertility was analyzed by chemical (total and organic carbon) and biological indicators of soils (biological quality index and microbial activities). Since metal contamination is related to urban de-sealed soil, we also monitored the concentration of Zn, Cu and Pb in soil and detected it in plant leaves. The results demonstrate that de-sealed urban soils rapidly restore their biological quality and fertility. Restoration of de-sealing soils can contribute to the recent growing interest reclamation of urban soils for improving the urban environment quality through the restoration of soil functions and related ecosystem services. Overall, the results of this study demonstrate that de-sealed soils can improve their functionality and can contribute to the recent growing interest in reclamation of urban soils for improving the urban environment quality.

Immobilization of Cd, Pb and Zn through Organic Amendments in Wastewater Irrigated Soils

Due to the scarcity of water, raw sewage effluents are often used to irrigate arable suburban soils in developing countries, which causes soil contamination with toxic metals. Soil microorganisms involved in biochemical transformations are sensitive to heavy metals contamination. The study was designed to investigate the effect of organic amendments on the microbial activity of cadmium (Cd), lead (Pb) and zinc (Zn) fractions and their bioavailability in soils contaminated with wastewater irrigation. Three metal contaminated soils under wastewater irrigation were collected, ground, sieved and added to incubation jars. Two organic amendments: wheat straw and chickpea straw, were applied (1% w/w) to the soil before incubation for 84 days at 25 °C. The CO2-C evolution after 1, 2, 3, 5, 7, 10 and 14 days was measured and thereafter was also measured weekly. Soil samples collected at 0, 14, 28, 42, 56, 70 and 84 days after incubation were analyzed for microbial biomass carbon (MBC). Sequential extraction for metal fractionation of samples was carried out collected at 0, 28, 56 and 84 days. Three soils differed significantly in evolved MBC and ∑CO2-C. Chickpea straw addition significantly increased soil MBC as compared to the wheat straw. Organic amendments significantly increased ∑CO2-C evolution from the soils, which was higher from chickpea straw. The addition of crop residues did not affect total Pb, Cd and Zn contents in soils. The concentration of exchangeable, carbonate bound and residual fractions of Pb, Cd and Zn decreased (6–27%), while the organic matter bound fraction increased (4–75%) with straw addition. Overall, the organic amendments improved microbial activity and reduce the bioavailability of toxic metals in wastewater irrigated soils. Furthermore, organic amendments not only reduce economic losses as they are cheap to produce but also minimize human health risks from heavy metals by hindering their entry into the food chain.

Behavior and mechanism of different fraction lead leach with several typical sulfate lixiviants in the weathered crust elution-deposited rare earth ore.

Recently, some new leaching agents without ammonium, such as magnesium sulfate (MgSO4) and aluminum sulfate [Al2(SO4)3], have been developed to eliminate ammonia nitrogen pollution in in situ mining process of the weathered crust elution-deposited rare earth ore (WCED-REO), but they might cause heavy metal contamination. In this study, characteristics and mechanisms of different fractions of lead (Pb) released by (NH4)2SO4, MgSO4 and Al2(SO4)3 leaching agents were investigated using batch experiments and column leaching tests. The experimental results showed that the amounts of Pb released by the different leaching agents followed the trend of Al2(SO4)3 > (NH4)2SO4 > MgSO4 under the same total cationic charge, and both the acid extractable and reducible fractions of Pb were released. The release of acid extractable fraction Pb was related to the cation hydration radius of NH4+, Mg2+, and Al3+, whereas the release of reducible fraction Pb was mainly influenced by the concentration of H+, especially at pH < 4.0. Furthermore, column leaching tests indicated that pH has little effect on the Pb contents of different fractions released by (NH4)2SO4 and MgSO4 in leaching the WCED-REO. Although Al2(SO4)3 released the largest contents of rare earth and Pb in leachate, the content of residual acid extractable fraction Pb in soil was the most after water injection (simulating the cleaning process after mining). This work can provide a scientific method and theoretical basis for comprehensively assessing the environmental impact of new leaching agents on WCED-REO mining.

Trace metals and metalloids in peri-urban soil and foliage across geologic materials, ecosystems, and development intensities in Southern California

Southern California is a mega-metropolitan area with abundant air pollution, complex geology, and diverse Mediterranean ecosystems. The objective of this study was to evaluate trace metal and metalloids (TMMs) (As, Cd, Co, Cr Cu, Ni, Pb, U, V, Zn) in soils and foliage of peri-urban areas and explore potential effects from human-development, ecosystems, and geologic material. Foliage of dominant native vegetation, soil samples (0–20 cm), saprolite, and unweathered rock samples were collected across fifty-four sampling sites in foothills spanning coastal Los Angeles and Orange counties to inland San Bernardino and Riverside counties. Soil As, Cd, Cu, and Pb concentrations were regionally elevated, but not as elevated as point-source polluted sites elsewhere. Soil Cd, Cr, Cu, Pb, and Zn concentrations were above EPA Ecological Soil Screening Levels. Further, enrichment factors (EF) normalized to Ti concentrations in bedrock suggest minor to moderate As, Cd, Cr, Cu, Pb, and V accumulation in soils. Our foliar TMM concentrations and bioaccumulation factors (BAF) (foliar and soil ratio) indicate no bioaccumulation and limited effects across geologic, development intensity, and ecosystems groups. Sedimentary-derived soils affected soil TMMs, but likely not through inheritance of TMMs but by promoting clay and organic matter availability. Proximity to higher development intensity resulted in As, Cd, Cr, Cu, and Pb accumulation in peri-urban soils. Foliar TMM concentrations and BAFs suggest geologic materials, human development, and ecosystem properties were not important factors and TMMs were likely controlled by plant uptake or ecophysiology.

Spatial Distribution and Risk Assessment of Heavy Metal Pollution in Farmland Soils Surrounding a Typical Industrial Area of Henan Province

In order to fully explore the spatial distribution of soil heavy metal contaminants in farmland soil surrounding a typical industrial area in Dakuai town, Xinxiang city, Henan Province, the concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn in the surface soil and within the soil profile were determined and assessed. The principal components were also analyzed for source apportionment to provide a theoretical basis for the control and prevention of heavy metal pollution. According to the results, the soils in the study area are severely contaminated by Cd and Cu and moderated contaminated by As due to the battery manufacture and Cu (e.g., pipe and wire) processing. The concentrations of Cd, Cu, and As in soils were (2.56±1.23) mg·kg-1, (205.58±157.49) mg·kg-1, and (15.27±4.14) mg·kg-1, respectively, which exceeds standards by 100%, 89.44%, and 3.40%, respectively. Accounting for the influence of pollution sources, terrain, runoff erosion, and prevailing wind direction, all heavy metal concentrations were higher in the south direction, lower in the north direction. The concentrations of Cd and Cu in soil profile samples decreased with depth, with highest concentrations at the surface, indicating the strong effect of industrial activities. Arsenic concentrations varied little with soil depth due to its strong migration ability in alkaline soil, again suggesting an industrial source. Among them, the soil of study area was severely contaminated by Cd and Cu (Level 5). Cd poses a severe potential ecological risk (Level 5) and Cu poses a medium risk (Level 2) in the study soils, while other heavy metals show low potential ecological risk (Level 1). The order of the risk identified was Cd > Cu > Ni > As > Pb > Cr > Zn. In addition, the combined potential ecological risk of heavy metals in the target area is severe. The principal component analysis showed that the high As, Cd, and Cu contents are mainly derived from industrial areas. Therefore, it is urgent to remediate Cd and Cu soil contamination in this area and implement precautions to limit As contamination.

Distribution Characteristics and Pollution Evaluation of Heavy Metals in Greenbelt Soils of Nanjing City

Concentrations and the spatial distribution of heavy metals (Cr, Cu, Zn, Pb, and Cd) in greenbelt soils in the main areas of Nanjing City, Jiangsu Province, were investigated and pollution levels were assessed using the single factor pollution index (SFPI), Nemerow integrated pollution index (NIPI), and potential ecological risk coefficient (PERC). The results showed that the average concentrations of heavy metals in greenbelt soils exceeded their background values, with the SFPI results ranked Cd > Pb > Cr > Cu > Zn, and the mean NIPI was 2.72 indicating that the greenbelt soils are moderately polluted. The PERC of each heavy metal (Cr, Cu, Zn, and Pb) was less than 10, indicating that the greenbelt soils present a slight ecological risk, while the PERC of Cd reached 97.32, indicating a strong ecological risk. The composite PERC of all heavy metals was less than 150, indicating a slight ecological risk overall. The five heavy metals showed a patchy spatial distribution, with high concentrations of Cr, Cu, Zn, and Pb in the greenbelt soils of northeast areas, and high concentrations of Cd in the southwest and northwest. Based on the results of study, Cd pollution in greenbelt soils in main areas of Nanjing City is relatively serious, which requires further attention.

Tree species as a biomonitor of metal pollution in arid Mediterranean environments: case for arid southern Tunisia.

We investigated the accumulation of Zn, Cu, Pb, and Cd in the soil and the leaves and bark of five common tree species (Eucalyptus occidentalis Endl., Acacia salicina Lindl., Cupressus sempervirens L., Casuarina equisetifolia L., and Tamarix aphylla (L.) Karst.) in the city of Gabès Tunisia to elucidate their bioaccumulation potential and determine their usefulness as biomonitors of metallic pollution in arid urban areas. Our results indicated that the bark had higher mean concentrations of Pb and Cd than leaves. In contrast, the leaves had higher mean concentrations of Zn and Cu than bark. No hyperaccumulation was detected for any of the analyzed metals in any of the studied species. E. occidentalis and T. aphylla had the highest mean concentrations of the investigated metals in leaves and bark. Based on the calculated metal accumulation index (MAI) values, these two species accumulated more metals than other studied tree species. Likewise, the concentrations of Zn, Cu, Pb, and Cd in soil had significant positive correlations with that in leaves and bark. Accordingly, E. occidentalis could be used for biomonitoring in arid areas subjected to industrial and traffic pollution. T. aphylla would be a good alternative when native species are a priority.

Investigation of lead sources in manioc flour from riparian communities in the Tapajós Region, Brazilian Amazon

From a previous pilot study, the Tapajos River basin riparian population was found to have elevated blood lead (PbB) levels, ranging from 0.59 to 48.3 μg/dL. Preliminary analyses of these results initially pointed to the metallic plates used in the production of manioc flour as a possible source. The main objective of this study was to investigate the potential environmental sources of Pb in the manioc flour in this region. The study was carried out in eight communities on the Tapajos River, where samples of manioc flour, metal plates and soil from manioc plantations were collected. In addition, samples of deposited sediments from the Tapajos River and its tributaries and riverbank sediments were collected. The metal composition was analyzed by SEM, XRF and GFAAS. The results show that the concentrations of Pb in manioc flour ranges from 0.08 to 0.31 mg/kg and the manioc paste from 0.004 to 0.037 mg/kg. The metallic plates used in the manioc-roasting process are made of carbon steel without Pb in the bulk alloy. Pb concentrations in soils where manioc roots were cultivated range from 8.9 to 26.1 mg/kg and Zn concentrations range from 12.7 to 59.1 mg/kg, indicating a contribution of polymetallic geological deposits. The clay-rich samples have high metal contents (including Pb, Zn and Cu). The Pb content of the clay samples ranges from 10.6 to 25.1 mg/kg. These results suggest that it is unlikely that the Pb found in the manioc flour originates from the metal plates used in its roasting process, rather, it seems to be associated to environmental factors determined by the local geology and soil composition.

Spatial heterogeneity of soil heavy metal content in Baiyinhua mining area, Inner Mongolia, China.

To evaluate the spatial distribution characteristics of soil heavy metal content in Xiwuzhumuqin Banner, Inner Mongolia, we analyzed the spatial heterogeneity of soil Cu, Cr, Pb, and Mn contents within 8 km distance of the mining area. Results showed that the contents of Cu, Cr, Pb and Mn in soil were 12.7, 32.6, 29.9 and 201.3 mg·kg-1, and their coefficients of variation were 26.8%, 33.9%, 27.1% and 45.7%, respectively. According to the model fitting by semi-variance function, the spatial distribution of Cu, Cr, Pb and Mn were consistent with the Gaussian model, Gaussian model, Gaussian model and linear model, respectively. Results of the spatial distribution pattern analysis showed that the spatial correlation levels of Mn, Cr and Cu were high, which were mainly affected by structural factors, but little affected by random factors. The spatial correlation level of Pb element was moderate, which was affected by both structural factors and random factors. Results of the fractal dimension analysis showed that the spatial distribution of four heavy metal contents was simple. Combined with 2D and 3D views, the four types of heavy metals all presented gradient distribution, which decreased with the increases of distance. The contents of Cu and Mn were mainly concentrated within 1.5 km from the mining area, while Cr and Pb were mainly concentrated within 2.0 km and 3.0 km from the mining area, respectively.

Investigation of Farmland Soil and Wheat Heavy Metal Contamination Character in Jinding of Lanping

The contents of Cd and Pb in soil and wheat in Jinding of Lanping in Yunnan were investigated and sampled. And single pollution index method, comprehensive pollution index method and correlation analysis were used to evaluate heavy metal contamination in wheat and soil. Zone A is in the upper reaches of the Pijiang River, and the zone does not contain large mines, where soil in the farmland is not polluted by the heavy metals Cd and Pb. The soil in zone B is slightly polluted by Cd and Pb, and the over-standard rate of the Cd of the samples measured is 75%, and the over-standard rate of the Pb of the soil is 25%. The condition of soil polluted by two heavy metals is Cd > Pb, and the heavy metal pollution of the soil in this Zone is mainly affected by mining activities. Zone C is in the lower reaches of the Pijiang River, and the soil in Zone C is not polluted by Cd and Pb. The content of Cd and Pb in the wheat in Zone A reached the standard and was not polluted. The wheat in Zone B was not polluted by Cd and Pb. Although Cd and Pb in the soil in this Zone was over-standard, it could be concluded that Cd and Pb in the soil did not migrate to wheat. The wheat in Zone C was not contaminated by Cd and Pb.

Assessment of heavy metal pollution in the agricultural soils, plants, and in the atmospheric particulate matter of a suburban industrial region in Dhaka, Bangladesh.

Unplanned industrialization and improper management of wastes and gases into open surfaces are affecting the agricultural lands causing heavy metal pollution. This study monitored a suburban industrial zone located beside the Dhaka Export Processing Zone (DEPZ) at the Dhaka district in Bangladesh. We studied the heavy metal (Fe, Mn, Cr, Cu, Ni, Co, Zn, Pb, and Cd) concentration in the agricultural soils, plants, and in the atmospheric particulate matter (PM). The soils were found moderately contaminated with Fe, Cu, Ni, Co, and Zn and less contamination with Mn, Cr, Pb, and Cd. The enrichment factor (EF) and pollution load index (PLI) concluded a moderate level of soil pollution in this region. Besides, the plant samples showed an excess level of Cr and a similar level of Cu, Ni, Co, Zn, Pb, and Cd compared with the levels of industrial polluted sites of Bangladesh. The atmospheric PM analysis showed the presence of Fe, Mn, Cu, Ni, Zn, and Pb metals. The EF showed the anthropogenic origin of Mn and Ni in the atmospheric PM. The statistical correlation (r < 0.0001) of soil and plant heavy metals showed the possibility of transfer of metals from soil to plant which will cause the increase of pollution intensity. Overall, this agricultural region became an intermediate pollution zone. This study will help the decision-maker become conscious of heavy metal pollution in the suburban regions to monitor agricultural lands from anthropogenic pollution.

Distribution and secondary enrichment of heavy metal elements in karstic soils with high geochemical background in Guangxi, China

Karst environments are globally significant, and the soils that develop on these landscapes often have unique geochemical features, including elevated–levels of metals. However, it has not been determined whether the enrichment of metals in soils is mainly controlled by parent rocks or secondary enrichment during weathering. In this paper, we studied the control of the accumulation of heavy metals in soils by parent materials and/or the process of soil formation. We examined the un–weathered carbonate and clastic bedrocks, as well as surface soils in a typical karst area in Guangxi of China. The spatial distribution of heavy metal (Cd, As, Cr, Cu, Hg, Ni, Pb, and Zn) concentrations in soils was mainly controlled by the geological background. Except for Cd, the concentrations of heavy metals in carbonate rocks were much lower than those in clastic rocks, whereas the soils derived from the carbonate rocks were highly enriched with heavy metals than those in clastic area. The enrichment of Cd in surface soils from the carbonate substrates was the result of the dual effect of secondary enrichment and parent rock inheritance, whereas the enrichment of other metals was mainly the result of secondary enrichment. During the weathering process of carbonate bedrock, great majority of the quantities of inherent heavy metals were leached, with only 2% of Cd being retained in situ. The high concentrations of soil Fe, Al, and Mn oxides, organic carbon and clay content (Al2O3/SiO2) were closely related to the enrichment of heavy metals in studied surface soils.

Accumulation of Potentially Toxic Elements in Viola L. (Sect. Melanium Ging.) from the Ultramafic and Non-ultramafic Soils of the Balkan Peninsula

The aim of the present study was to assess the metal concentrations in five species of the genus Viola L. (section Melanium) from 12 ultramafic outcrops and two non-ultramafic (prolluvium and dolomite) soils from Serbia and Bosnia and Herzegovina. The concentrations of P2O5, K2O, Ca, Mg, Fe, Mn, Zn, Cu, Cr, Co, Cd and Pb in soils and plant samples, as well as their shoot-to-root ratio, biological concentration and accumulation factors were determined. Five investigated Viola species growing on 14 different localities displayed considerable differences in concentration of potentially toxic elements in their roots and its accumulation in their shoots. Viola kopaonikensis and V. beckiana from ultramafic soils could be classified as strong Ni accumulators, since moderately high level of Ni was measured in their shoots (up to 266 mg kg−1 and 337 mg kg−1, respectively), while in V. tricolor high amount of the same element was accumulated in the roots (up to 395 mg kg−1). Population of V. beckiana from dolomitic site in Bosnia and Herzegovina accumulated high concentrations of Pb in the shoots (67.1 mg kg−1), as well as of Cd in both roots and shoots (81.1 mg kg−1 and 60.5 mg kg−1). The results also suggest that V. kopaonikensis populations from the ultramafic soils of Serbia emerge as Cr accumulators, which is quite rare trait within the genus Viola. It seems that species from Melanium section apply quite different strategies against toxic elements. Future studies should strive to explain what adaptive mechanisms are hidden behind it.

Current Status and Temporal Trend of Potentially Toxic Elements Pollution in Agricultural Soil in the Yangtze River Delta Region: A Meta-Analysis.

Potentially toxic elements (PTEs) pollution in the agricultural soil of China, especially in developed regions such as the Yangtze River Delta (YRD) in eastern China, has received increasing attention. However, there are few studies on the long-term assessment of soil pollution by PTEs over large regions. Therefore, in this study, a meta-analysis was conducted to evaluate the current state and temporal trend of PTEs pollution in the agricultural land of the Yangtze River Delta. Based on a review of 118 studies published between 1993 and 2020, the average concentrations of Cd, Hg, As, Pb, Cr, Cu, Zn, and Ni were found to be 0.25 mg kg−1, 0.14 mg kg−1, 8.14 mg kg−1, 32.32 mg kg−1, 68.84 mg kg−1, 32.58 mg kg−1, 92.35 mg kg−1, and 29.30 mg kg−1, respectively. Among these elements, only Cd and Hg showed significant accumulation compared with their background values. The eastern Yangtze River Delta showed a relatively high ecological risk due to intensive industrial activities. The contents of Cd, Pb, and Zn in soil showed an increasing trend from 1993 to 2000 and then showed a decreasing trend. The results obtained from this study will provide guidance for the prevention and control of soil pollution in the Yangtze River Delta.

Quantitative analysis of the main sources of pollutants in the soils around key areas based on the positive matrix factorization method.

Quantitative identification of the main sources of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in soils around multiple types of key areas is of great significance for blocking pollution sources. However, there is a lack of more comprehensive relevant research. In this study, Beijing was taken as the research area and four main sources were identified using the positive matrix factorization (PMF) method. The concentration of Pb, PAHs, Cr, and Hg in soils was significantly affected by the presence of landuse type, road traffic, natural factor, and industrial production, respectively, and the farmland, distance to main road, Proterozoic Changcheng-Jixian parent material and cinnamon soil type, and the gross industrial production make greater contributions to these four factors respectively than other variables. Moreover, the uncertainty of the PMF indicates that this four-factor PMF solution is stable and appropriate. These results provide support for the comprehensive control of soil environmental risks.

Analysis of Heavy Metal Contents of Marsilea crenata Presl. Leaves and Soils from East Java Province, Indonesia

Introduction: Marsilea crenata Presl. grows in East Java Province, Indonesia, and showed several pharmacological activities due to its phytoestrogen content. Research indicated its phytoremediation property, and therefore has an impact on heavy metal accumulation in the plants. Lead, cadmium, and mercury are amongst heavy metals that are toxic to the human body. This study aimed to determine and compare Pb, Cd, and Hg mineral contents of soils and leaves of the plants grew in Batu, Pasuruan, Surabaya, and Kediri cities in the province. Method: 10 g of dried powdered leaves and soils were put in separate crucible porcelains, and add 2ml of nitric acid. All were burnt in low heat until white smoke were not formed, and then stood to cool. Ashes obtained were examined using AA 6200 Atomic Absorption Spectrometer (AAS). Result: Showed that leaves samples from the areas showed no Pb and Hg mineral contents that exceeded the permissible limit. Batu City leaf sample had Cd heavy metal content of 2.79 ± 0.01 ppm, which exceeded the permissible limit. Conclusion: Analysis of heavy metal contents of soils from all of the areas showed no exceed limit of Pb and Hg mineral concentrations. Cd soil contents of Surabaya and Kediri cities, were 0.73 ± 0.00 and 2.61 ± 0.08 ppm respectively.