Accumulation Of Metals In Soils Research Articles

Metal accumulation and health risk assessment in wastewater used for irrigation around the Agra Canal in Faridabad, India.

Wastewater application for irrigation is a traditional and economic tool in developing nations. Yet prolonged use of wastewater for agricultural activities contributes to the accumulation of metals in both soil and vegetables. This study investigated the accumulation and contamination of vegetables with heavy metals ensuing from the application of wastewater from the Agra Canal and the associated risks posed to human health. Three sites across the Agra canal were selected for sampling (CW-1, CW-2, and CW-3), where untreated wastewater is being used to irrigate vegetables (spinach, coriander, radish, and garlic crops), for which tube-well water (TW) from a village served as the control site. Water, soil, and vegetable samples were collected from all sites. The presence in them of various metals, such asAs, Pb, Cr, Mn, Cu, Zn, and Ni, was detected at all four sites. The greatest content of Mn was found in CW-1's water (7.91 mg/L), soil (633.77 mg/kg), and in spinach 368.12 (mg/kg) grown there. Significantly higher metal concentrations were observed in vegetables irrigated with wastewater than in tube-well-irrigated vegetables, with the metals ranked in accumulation as follows Mn > Zn > Ni > Cu > Cr > Pb > As. Our results also revealed that metal bioaccumulation varied enormously between foliar and non-foliar vegetables, as well as among the four sites. Daily metal intake (DMI) and health risk index (HRI) analyses suggested that children consuming contaminated vegetables are at higher risk than adults. The HRI for Mn, Ni, and Pb was above 1, which indicated significant health hazards to humans consuming the wastewater-irrigated vegetables. Moreover, the control site where tube-well water was used had an HRI below 1, signifying a negligible health risk for its consumption. Therefore, we may conclude that the extensive application of contaminated water for a longer duration would likely further increase metal accumulation in soil and vegetables that may be hazardous to living organisms.

Effect of Soil Degradation and Remediation in Technogenic Barrens on the Uptake of Nutrients and Heavy Metals by Plants in the Kola Subarctic

To assess the state of plants and their response to changes in soil properties, the elemental composition of leaves of widespread and pollution-tolerant species Betula pubescens Ehrh. and Salix caprea L. has been studied near the nonferrous metallurgy enterprises in the Kola Peninsula. The content of nutrients and heavy metals in the leaves of undergrowth on technogenic barrens and remediation sites differing in remediation technologies has been analyzed. According to the results of leaf diagnostics, both species under barren conditions are characterized by a noticeable deficiency of K, Ca, P, and, especially, Mn and Zn. The leaves of both species accumulate Ni, Cu, Co, As, Cr, Fe, Al, Pb, V, and S. Willow leaves contain more Cd, Co, Cr, Ni, Cu, Al, Fe, As, S, Ca, K and less Mn than birch leaves. Chemophytostabilization has little effect, and the covering of contaminated soils with a constructed fertile layer leads to the enrichment of birch and willow leaves with Ca, K, and P. Under conditions of continuing atmospheric emissions and gradual accumulation of bioavailable heavy metals in soils after the remediation, the accumulation of metals in leaves is largely determined by the distance from the pollution source, reflecting the possibility of both root and foliar uptake. The concentrations of Ni and Cu in leaves in 2018 did not decrease compared to 2011. The low, albeit varying, ratios of the contents of heavy metals in undergrowth leaves and in the soil and weak correlation of heavy metal contents in these media indicated that B. pubescens and S. caprea retain their ability to regulate their chemical composition even under extreme conditions of technogenic barrens. At the same time, supporting the protective capabilities of plants via optimizing mineral nutrition and soil acidity in combination with a reduction in atmospheric pollution is a prerequisite for efficient remediation of technogenic territories in the Far North.

Magnesium Oxide Nanomaterial, an Alternative for Commercial Copper Bactericides: Field-Scale Tomato Bacterial Spot Disease Management and Total and Bioavailable Metal Accumulation in Soil.

Copper (Cu) is the most extensively used bactericide worldwide in many agricultural production systems. However, intensive application of Cu bactericide have increased the selection pressure toward Cu-tolerant pathogens, including Xanthomonas perforans, the causal agent of tomato bacterial spot. However, alternatives for Cu bactericides are limited and have many drawbacks including plant damage and inconsistent effectiveness under field conditions. Also, potential ecological risk on nontarget organisms exposed to field runoff containing Cu is high. However, due to lack of alternatives for Cu, it is still widely used in tomato and other crops around the world in both conventional and organic production systems. In this study, a Cu-tolerant X. perforans strain GEV485, which can tolerate eight tested commercial Cu bactericides, was used in all the field trials to evaluate the efficacy of MgO nanomaterial. Four field experiments were conducted to evaluate the impact of intensive application of MgO nanomaterial on tomato bacterial spot disease severity, and one field experiment was conducted to study the impact of soil accumulation of total and bioavailable Cu, Mg, Mn, and Zn. In the first two field experiments, twice-weekly applications of 200 μg/mL MgO significantly reduced disease severity by 29-38% less in comparison to a conventional Cu bactericide Kocide 3000 and 19-30% less in comparison to the water control applied at the same frequency (p = 0.05). The disease severity on MgO twice-weekly was 12-32% less than Kocide 3000 + Mancozeb treatment. Single weekly applications of MgO had 13-19% higher disease severity than twice weekly application of MgO. In the second set of two field trials, twice-weekly applications of MgO at 1000 μg/mL significantly reduced disease severity by 32-40% in comparison to water control applied at the same frequency (p = 0.05). There was no negative yield impact in any of the trials. The third field experiment demonstrated that application of MgO did not result in significant accumulation of total and bioavailable Mg, Mn, Cu, or Zn in the root-associated soil and in soil farther away from the production bed compared to the water control. However, Cu bactericide contributed to significantly higher Mn, Cu, and Zn accumulation in the soil compared to water control (p = 0.05). This study demonstrates that MgO nanomaterial could be an alternative for Cu bactericide and have potential in reducing risks associated with development of tolerant strains and for reducing Cu load in the environment.

Dominant environmental factors influencing soil metal concentrations of Poyang Lake wetland, China: Soil property, topography, plant species and wetland type

Although an important sink for contaminants including metals, wetland soils can release metals and thus cause a secondary pollution when environmental condition changes. Metals in wetland soils are influenced by a variety of environmental factors, including soil property, topography, wetland type, and plant species. However, the degree of importance of these environmental factors to wetland soil metals has not yet been clearly explained. In this study, the effect of these environmental factors on soil metal concentrations (i.e., Cr, Ni, Cu, Zn, As, Cd, and Pb) was explored in Poyang Lake wetland. Correlation, redundancy, and variance decomposition analyses were employed. The results indicate that the concentrations of Cu, Pb, Cd, Cr, and Zn were higher than their background values. Statistical analysis showed that all environmental factors explained 55.90% of the total variance (either p < 0.01 or p < 0.05). Soil properties, mainly TN, TP, NO3−-N, PO43−-P, and TOC played a dominant role on soil metal concentrations, which explained 27.91% of the total variance, followed by wetland type and topography, which explained 5.55% and 3.19% of the total variance, respectively. Soil nutrients significantly promoted metal aggregation in soil (p < 0.01 or p < 0.05). Lower elevations were favorable for soil metal accumulation (p < 0.05). Wetland type indirectly influenced soil metal concentrations, where wetlands with low flat terrain promoted soil nutrients accumulation, thus enhancing metal accumulation by soils. Plant species explained 6.72% of the variance, and Artemisia and Phalaris were positively correlated with specific metals in soils. This study provides a theoretical basis for retaining healthy wetland ecosystems.

Biochemical Responses of Medicinal Plant Tussilago farfara L. to Elevated Heavy Metal Concentrations in Soils of Urban Areas.

This study was conducted in Tyumen (Russian Federation) to establish the effects of heavy metals’ (Cu, Zn, Fe, Mn, Pb, and Cd) accumulation in soil and coltsfoot, as well as plants’ biochemical responses to such an accumulation. The mobile and acid-soluble heavy metal fractions in soils, and the heavy metal contents in plants, were determined by atomic absorption spectrophotometry. The Cu, Zn, Fe, Mn, and Pb concentrations in soils exceeded background values. Pb content at the battery manufacturing plant was above the maximum permitted concentration. The percentages of the mobile heavy metal fractions decreased in the following order: Mn > Zn > Cu > Fe. The greatest heavy metal accumulation in soils and plants was found at the battery manufacturing and metallurgical plants examined in our study. Heavy metals’ accumulation in the aboveground part of Tussilago farfara decreased in the following order: Fe > Zn > Cu > Mn > Pb > Cd. The accumulation of heavy metals stimulated the synthesis of photosynthetic pigments by 6–30%. Heavy metals provoked oxidative stress in cells, increasing the concentration of lipid peroxidation in products by up to 80%. Plant phenolics and flavonoids in the urban area of our study decreased compared to those in the control by 1.05, reaching up to 6.5 times. The change in coltsfoot catalase activity both increased and declined. Biochemical responses and heavy metal accumulation in coltsfoot from urban areas limit its use for medicinal purposes.

Influence of Copper Contamination on Soil Physico-chemical Properties, Microbial Population and Enzyme Activities

Heavy metals are known for their phytotoxicity and commonly used in agrochemicals to control plant pathogens. Accumulation of heavy metals in soil may occur through extensive use of heavy metal-based agrochemicals over time or from industrial pollution. However, this study was focussed on the immediate effect of the heavy metal, Copper (Cu) contamination on soil microbial population and soil enzyme activities (viz. acid phosphatase, β-glucosidase, urease &amp; dehydrogenase). Soil with graded doses of Cu was prepared by treating soil samples with varying concentrations of Copper (ll) sulphatepentahydrate (CuSO4.5H2O) where three levels of CuSO4.5H2O (50, 100 &amp; 200 mg/kg soil) treatments were formulated along with control. A significant decrease in soil microbial population and soil enzyme activities was observed in all treatments.

Effects of nearly four decades of long-term fertilization on the availability, fraction and environmental risk of cadmium and arsenic in red soils

Fertilizers are important for agricultural production because they can effectively promote crop productivity. However, long-term fertilization can cause heavy metal accumulation in soils and crops. This study utilized sequential extraction, the diffusive gradient in the thin films (DGT) technique and risk assessment models to estimate the effects of the longest long-term fertilization (38 years) in China on cadmium (Cd) and arsenic (As) accumulation in soils. The treatments included no fertilization (CK); inorganic nitrogen, phosphorus, and potassium fertilization (NPK); manure fertilization (M); and NPK plus M cofertilization (NPKM). The results indicated that the soils treated with NPKM, M and NPK had significantly increased total and available concentrations of Cd and As after 38 years of long-term fertilization. Cd mainly originates from cattle manure, while As originates from phosphate fertilizer. Sequential extraction results indicated that the application of manure increased the acid/exchangeable fraction (F1) and organic matter-bound fraction (F3) of Cd and As. The risk assessment results showed that the environmental risks of both Cd and As increased during long-term fertilization, and Cd contamination in the soil was at a moderate-high level, while As remained at a relatively low level. According to the calculations of the maximum numbers of years of soil productivity and rice production, Cd was labile and accumulated in the soils, and As was more labile than Cd in terms of accumulating in rice, indicating that the true risk from As in rice is higher than that from Cd. Controlling the heavy metals in fertilizers, mitigating effective amendments, and identifying plant types that accumulate low amounts of contaminants may be good choices for cleaner crop production.

Long-Term Irrigation with Treated Municipal Wastewater from the Wadi-Musa Region: Soil Heavy Metal Accumulation, Uptake and Partitioning in Olive Trees

Utilization of treated wastewater (TWW) for agricultural purposes has grown over the past few years because of limited available water resources. This study was performed to assess the long-term irrigation of treated wastewater from the Wadi-Musa region on the accumulation of heavy metals in soil and their uptake and translocation to various parts of olive trees. Fifteen year old trees that had been grown and irrigated with treated wastewater resources since their establishment were used in this study. Irrigation water, soil, and plant samples (root, stem bark, leaves, fruits) were collected and chemically analyzed for their heavy metal content. Accumulation of heavy metals in irrigation water and soil were found to be within the acceptable range for the safe use of treated wastewater according to the standards of the WHO. However, long-term and continuous irrigation with TWW resulted in significant accumulation of heavy metals in plant parts when compared to their levels in irrigation water and soil. Uptake of metals was consistent among plant parts with the highest concentrations for Fe, Mn, Pb and Zn, and the lowest concentrations for Ni, Cr and Cd. Assessment of the bioaccumulation factor (BFC) and translocation factors (TF) of heavy metals into different plant parts indicated selective absorption and partitioning of these heavy metals into different plant parts. High BCF values were observed for Fe, Cu and Ni in roots and fruits, and Fe, Mn, Cd and Pb in leaves. Translocation factors of metal ions were variable among plant parts. Fruits had the highest TF for Cu, Cd and Zn metals, and the lowest for Mn and Fe, while leaves have the highest TF for Fe, Zn and Mn and the lowest for Cd and Pb. The results of this study indicate that olive trees are heavy metal accumulators, caution should be considered in long-term use of TWW and periodic assessment of possible hazards, especially on fruits and oil quality is required.

Long-term effects of liquid swine manure land surface application in an apple orchard field on soil bacterial community and heavy metal contents in apple (Malus pumila Mill.).

This study investigated the impact of liquid swine manure (LSM) land surface application in an apple orchard on soil health and copper (Cu) and zinc (Zn) in soil and apple. Three apple plots were selected, among which two for LSM application for 5 (AY5) and 11 (AY11) years with different application rates, a long-term inorganic fertilizer application plot as the control treatment (AY0). The soil and apple samples were collected for analysis of soil physicochemical properties, bacterial diversity and abundance, and the contents of Cu and Zn in soil and apple. Results showed that the LSM application significantly increased the concentration of soil nutrients with the highest in AY5, which has a high application rate of LSM. After 5 or 11 years applied, the content of total nitrogen (TN) in AY5 and AY11 increased by 125.2% and 96.7%, total phosphorus (TP) increased by 167.6% and 148.6%, and soil organic matter (SOM) increased by 180.7% and 120.6%, respectively. The AY5 treatment significantly lowered OTUs and decreased Shannon index trend with a negative correlation between soil organic matter and Shannon index. The six predominant bacterial phyla in different treatments were similar, but the LSM application significantly increased the abundance of Chloroflexi and Firmicutes. However, the abundance of Actinobacteria and Acidobacteria significantly decreased in AY5 as compared to control treatment, followed by a significant positive correlation between the abundance of Acidobacteria and soil pH. Besides, LSM application significantly increased the contents of soil Cu, Zn, and apple Zn. Overall, the results illustrated that appropriate application rate of LSM can effectively improve apple orchard soil quality and bacterial community structure, but it will increase the risk of heavy metal accumulation in soil and apples.

Availability of heavy metals to cabbage grown in sewage sludge amended calcareous soils under greenhouse conditions

Compared to noncalcareous soils, data on the soil-to-plant transfer of heavy metals and their response to sewage sludge (SS) in calcareous soils with diverse properties are limited. Cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) transfer from soil to cabbage (Brassica oleracea L. var. capitata) under greenhouse conditions in 30 diverse soils amended with two types of sewage sludge (non-spiked and spiked with heavy metals) were investigated. Three transfer factors were calculated for heavy metals in three treated soils including control soils (CS), soils treated with non-spiked SS (NSS), and soils treated with spiked SS (PSS). The bio-concentration factor of heavy metals from soil to root (BCFRoots) in cabbage in three treatments was as follows: CS: Pb > Cu > Co > Zn > Ni; NSS: Pb > Co > Cu ≥ Zn > Ni; and PSS: Pb > Cd > Zn > Co > Cu > Ni. The same order was found for the bio-concentration factor of heavy metals from soil to shoots (BCFShoots) in PSS, and in CS and NSS treatments except that the position of Co, Cu, and Zn was changed. Based on the heavy metals translocation from plant roots to shoots, Cd, Cu, and Zn were the heavy metals that posed the highest risk due to the higher shoot content in all treatments, whereas Ni and Pb posed relatively lesser risk. Generally, the percentage of sand and silt in BCFRoots and BCFShoots was quite effective for Co, Ni, and Zn and it seems that soil texture is an important variable in heavy metals bioavailability. In conclusion, our findings highlight the significance of using SS to increase cabbage growth in soils contaminated with heavy metals. Furthermore, cabbage may be a good choice for phytoremediation of heavy metal-contaminated calcareous soils in terms of soil remediation. Novelty statement In recent years, sewage sludge production has increased as well as related waste disposal strategies because of the increasing population and growing demand for agricultural products. Sewage sludge utilization as a low-cost fertilizer has spread in some parts of Iran and the world. On the other hand, unnecessary and unproductive use of sewage sludge results in the accumulation of heavy metals in soils, adding them to food and the potential risk to human health. Currently, work on the transfer of heavy metals from soil to plant after soil treated with sewage sludge has focused on the bioavailability of heavy metals using specific extractants. The assessment of the transfer of heavy metals from soil to different parts of plants using sewage sludge has been less studied. In this study, the transfer of heavy metals (Cd, Co, Cu, Ni, Pb, and Zn) from several soils (30 soils samples) having diverse physical and chemical properties to the tissues of the cabbage plant in control soils, and two types of sewage sludge (nonspiked and spiked with heavy metals) were investigated. The novelty of this study is that the measured bio-concentration factor of heavy metals from soil to root and from soil to shoot and translocation of heavy metals from plant roots to shoots and correlations between these parameters and soil properties are reported for the first time in diverse calcareous soils.

Effect of Sewage Sludge on Heavy Metals Accumulation in Soil and Wheat, Mung Bean and Quinoa Crops

This study was conducted to study the effects of sewage sludge application to agricultural soil on the heavy metal accumulation in soil and plant and on availability of certain nutrients for plant together with the productivity of wheat, mung bean, and quinoa. The experiment were included four treatments i.e., (Control; inorganic fertilizer according to Ministry of Agriculture-Iraq.; sludge (the amount of sludge containing MoAR recommendation) of N without any addition of mineral N; and twice the amount of sludge without any addition of mineral N) with four replications in the feed crop studies station of the Ministry of Agriculture - Haditha agriculture division located in the village of Sakran (Hasweh Al-Jazeera) of Haditha district 260 km west of Baghdad during the seasons 2017-2018.2019. The applied sludge was described and soil was analyzed prior to cultivation. Upon harvesting, the heavy metals (Cd, Pb, Ni and Cr) were estimated in soil and plant in addition to certain nutrients (Total N, mineral N, available P, macronutrients) and organic matter. About heavy metal in soil and plant, significant buildup of the heavy metal in soil and plant was noticed by increasing the addition of sludge as compared to the control. Significant increase in organic matter and total N of soil in sludge-fertilized treatment was noticed as compared to the control. Moreover, a significant increase in mineral N, available P, Cu, Mn and Zn was also noticed by increasing the addition of sludge. There was significant increasing in plant productivity for various crops during the seasons by increasing the addition of sludge as compared to the control.

Health Risk Assessment of Heavy Metal Toxicity Utilizing Eatable Vegetables from Poultry Farm Region of Osun State

Heavy metals are present everywhere in the environment attributable to both geogenic and anthropogenic inputs and humans are vulnerable to them via various exposure pathways. Heavy metal accumulation in soils and plants is of grave concern because of the possible human health risks. This research article examined the seasonal concentrations of arsenic, cadmium, copper, iron, lead and zinc in leafy vegetables of Talinum triangulare and Vernonia amygdalina samples planted in some poultry farms and determine the risks involved in consumption of that vegetables. Flame Atomic Absorption Spectrophotometer was applied to evaluate the contents of the metals in the vegetables. Quality monitoring procedures comprised blank analysis, recovery test and calibration of standards. Descriptive and inferential statistics were adopted for data analyses. Hazard quotient, daily intake of metals, health risk index and transfer factor were also determined. The pattern of metals mean value in the soil was As > Fe > Zn > Pb > Cu > Cd while for vegetables was Fe > Zn > As > Cu > Pb > Cd. The TFs pattern for metals from soil to plant was Zn > Fe > Cd > As > Cu > Pb for Talinum triangulare and Fe > Zn > Cd > As > Cu > Pb for Vernonia amygdalina in both seasons. The sequence of the DIM value was Fe > Zn > As > Cu > Pb > Cd for both plants. The results indicated very high HRI and THQ values for As (22.60 and 61.00). This asserted that the intake of vegetables planted on the soil of the farms studied present a health risk for humans with regard to the evaluated metals.

Sewage sludge amendment affects spinach yield, heavy metal bioaccumulation, and soil pollution indexes

Use of sewage sludge (SS) in crop production is a feasible strategy for its disposal; however, its application may pose an adverse impact on soil and human health. Therefore, identification of the permissible level of SS is essential to prevent soil contamination. This research not only evaluated the impact of SS application on spinach (Spinacia oleracea L.) biomass yield but also tracked the accumulation of heavy metals in soil and plants. A pot experiment was conducted on Inceptisol with different levels of SS (0, 5, 10, 15, 20, 25, 30, 35, and 40 t ha−1) with recommended dose of fertilizers (RDF). The applications of SS at 20 t ha−1 resulted in the highest biomass yield; however, the concentration of zinc (Zn) and cadmium (Cd) has exceeded the safe limit in leaves. Heavy metal accumulation in the plant was the highest in SS at 40 t ha−1. Spinach grown at 20 t ha−1 and higher dose of SS exceeded the safe limit of Zn and Cd concentration in leaves, and the translocation factor (TF) of lead (Pb) and Cd was found to be > 1. The hazard quotient (HQ) of Pb > 1 at higher doses of SS indicates health hazard if spinach is used for consumption. Assessment of health risk showed that there was a possibility of Pb hazard at a high dose of SS (HI > 1). Evaluation of various soil pollution indexes revealed that the addition of SS enhanced the buildup of Cd and chromium (Cr) in soil. This study advocated the use of SS at 10 t ha−1 to sustain soil quality with no risk of food chain contamination.

Rice cultivation in former rubber land without soil remediation contribute toxicity risk of heritable heavy metals contamination

The rubber-based intercropping management system (RBIS) land management using chemical fertilizer and herbicides cause heavy metal accumulation in soil. Rice is a good heavy metal bioindicator to monitor soil quality and often integrated with RBIS while rubber trees are young as subsistence farming. Heavy metal accumulation in soil and hill paddy grown on former rubber land and specialized paddy field (control) had been assessed to determine whether harvested rice grain poses toxicity risk. Grain harvested from specialized paddy land was safer to consume as none of the selected heavy metal concentrations in rice grain had exceeded the permissible limit of Malaysia Food Regulation 1985 (MFR 1985). Meanwhile, hill paddy grown intercropping with young rubber trees on former rubber land had accumulated a high amount of heavy metals in rice grain whereby nonessential heavy metals like arsenic, cadmium and lead had exceeded the permissible limit of MFR 1985. Commonly, indigenous hill paddy belongs to tall paddy variety group can grow more than 120 cm tall. All harvested hill paddy landraces grown on specialized paddy field surpassed 120 cm. Nevertheless, all hill paddy landraces that were cultivated in former rubber land were below 100 cm tall indicated that heavy metal phytotoxicity occurred in plants. Rice grain produced in former rubber land poses toxicity risk to consumers due to unsustainable conventional agricultural management practice. Soil degradation needs to be prevented as it can impact food safety and food security. Further soil remediation requirement must be determined to ensure high productivity and safety.

A Field Evidence of Cd, Zn and Cu Accumulation in Soil and Rice Grains after Long-Term (27 Years) Application of Swine and Green Manures in a Paddy Soil

Although inorganic and organic manures with high concentrations of heavy metals can lead to accumulation or contamination of heavy metals in soils, there are few reports on the effects of long-term application of swine and green manures on the accumulation of heavy metals in rice grains in paddy soils. A long-term field experiment, which was established in 1990 in paddy soil in Hangzhou, China, was used to investigate the effects of inorganic and organic manures on the availability and accumulation of heavy metals in soil and uptake by rice plant. The results showed that long-term application of nitrogen, phosphorus and potash (NPK) plus green manure or swine manure, and swine manure only increased 202%, 146%, and 100% for total Cd, and 5.5%, 7.6%, and 6.6% for total Cu in rice grains, respectively compared to the control without fertilization. Total Zn in rice grain was significantly increased by 13.9% for the treatment of NPK plus green manure. The accumulation of Cd, Zn, and Cu in rice grains after long-term application of swine and green manures is due to the combined effects of the increased concentrations of total and EDTA extractable Cd, Zn, and Cu in soil and the changes of soil properties. Furthermore, the highest bioconcentration factor for Cd was found in the treatment of NPK plus green manure while for Zn and Cu it was observed in NPK treatment. Thus, it may be concluded that green manure and manure with increased Cd, Zn, and Cu in rice grain results in a potential risk of metal accumulation in paddy soils.

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.

Impact of Irrigation with Polluted River Water on the Accumulation of Toxic Metals in Soil and Crops in the Region of Dhaka, Bangladesh and Potential Effects on Health

The present study was designed to investigate the detrimental effects of toxic metals on agricultural practices carried out with polluted river water from one of the most polluted rivers, the Turag in Dhaka city, Bangladesh. Toxic metal concentrations in irrigation water, soil and rice grains (Oryza sativa) were measured from three different sites near the river. Bioaccumulation factors (BAF) were calculated to recognize the transfer of toxic metals from the soil to rice grains. The estimated daily intake (EDI), target hazard quotient (THQ), total target hazard quotient (TTHQ) and the target carcinogenic risk (TR) were calculated to evaluate the health risks. All values from these three sites were compared to the values obtained from a nearby site where irrigation was carried out with bore-well water. The mean concentrations of Zn, As, Cu, Ni, Pb and Cr in rice grains were 1.71 ± 0.52, 2.20 ± 0.84, 1.47 ± 0.17, 1.27 ± 0.10, 1.98 ± 0.21 and 0.21 ± 0.09 ppm, respectively, indicating that the concentrations of As and Pb were much higher. For all sites, THQ values for As and Pb were higher than 1.0 indicating that consumption of such rice will have a long-term, harmful effect on consumers. Furthermore, the TR values for As and Pb were higher than the threshold level (10−6), implying that the lifetime cancer risk is increased for residents eating this rice. Toxic metals intrude into the river water as well as the bore-well water. Rice cultivated at all sites is thus burdened with toxic metals that make it unsafe for human consumption.

Accumulation of toxic elements in soil and date palm (Phoenix dactylifera L.) through fertilizer application

Dates are the staple food for Arabs as well as the major export crop in the Middle East. In this work, we analyzed the concentration of toxic elements in commonly used fertilizers and evaluated metal accumulation in soil and date palm. Different types of fertilizers randomly selected from fertilizer dealers in the UAE were investigated for their toxic metals. Soil and plant samples collected from continuously fertilized date plantations were analyzed. Sandy loam soil (0–30 cm) samples were collected from date palm plantations continuously fertilized for more than 10 years (11 samples) and unfertilized date palm plantations (11 samples). A significant increase in chromium (Cr) and cadmium (Cd) was observed in the leaves of the fertilized date palms, whereas, in date palm fruits, the concentration of copper (Cu) was higher. A distinct correlation was observed between the total and the available metal concentrations in the soil for Cd and Cu. The average concentrations of toxic metals, however, remained within the limits of those used worldwide. It is important to encourage manufacturers to indicate the concentrations of toxic elements on the fertilizer labels due to environmental and health implications.

THE EFFECTS OF THE APPLICATIONS OF ZEOLITE AND BIOCHAR TO THE SOILS IRRIGATED WITH TREATED WASTEWATER ON THE HEAVY METAL CONCENTRATIONS OF THE SOILS AND LEACHING WATERS FROM THE SOILS

The reuse of wastewaters for agricultural irrigation is a method used in arid and semi-arid regions. The heavy metal accumulation in soils caused by wastewaters and the heavy metals transported by the waters leaching into the underground from these soils are important environmental issues. The study investigates the effects of Biochar (Bc) and Zeolite (Zt) applications on the heavy metal accumulation in soils (entisol and vertisol) that were irrigated with treated urban wastewater (TWW). The effects of Bc and Zt on the heavy metal concentrations of the leaching water (LW) from the soils were investigated as well. In the study, increasing doses of Bc (1%, 2%, and 4%) and Zt (5%, 10%, and 20%) were mixed into two soil classes of heavy- and fine-textured soils. The mixtures were irrigated with TWW at certain intervals. At the end of the trial, the chromium (Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), lead (Pb), and cadmium (Cd) contents of the samples collected from the soils and leaching irrigation waters were determined. The results revealed that Bc and Zt caused heavy metal accumulation in both soil classes, while they decreased the heavy metal concentrations of the LW. The adsorbents are commonly used as soil amendments and have been determined to cause heavy metal accumulation in soils but reduced the heavy metal concentrations in waters by serving as filters.

The assessment of soil contamination with heavy metals in the Vladimir city

To analyze heavy metal contamination of urbanized soil in the Vladimir city, the soil was sampled and studied. The city area is represented by sod-medium podzolic and gray forest urbanized soil. Soil samples analysis included lead, zinc, copper, nickel, manganese, cobalt and chromium. The resulted parameters were compared to the maximum permissible concentrations and background values. The regularities between the studied sites proximity to the industrial enterprises and heavy metals concentration in soil have been found. The coefficients of heavy metals accumulation in soil have been calculated and the metals as priority pollutants with the highest accumulation coefficient have been identified. By calculating the cumulative accumulation index, the city area has been differentiated according to the hazardous degree. The research peculiarity comprises the sampling locations selection – school sites, as the child population is the most vulnerable to the diseases, associated with the heavy metals accumulation in soil.