Metal-contaminated Soils Research Articles

Heavy metal contamination in soils of industrial estates of Tamil Nadu, India and source identification by magnetic susceptibility.

An increase in erratic industrial activity has been a major contributing factor to the significant contamination in environmental matrices. This study aimed to ascertain the level of heavy metal contamination in soils in major industrial estates of Tamil Nadu as well as the threats to human health and the environment that concomitant with it. This led to the use of the total reflection X-ray fluorescence (TXRF) spectroscopy technique to analyse 31 soil samples. Thus, the mean heavy metal concentrations were found to be in the ascending order: As < Ni < Pb < V < Cu < Zn < Cl < Mn < Sr < Cr < Al < Fe. Pb, Cr, Cu, As, and Zn have been identified as predominantcontaminants in the study area using the conventional pollution indices such as geo-accumulation index (Igeo), contamination factor (CF), and enrichment factor (EF). The magnetic susceptibility measurements indicates that the percentage of frequency dependence of magnetic susceptibility of the studied soil samples varied from 0.88 to 11.15 and that represents the presence of admixture ofsuperparamagnetic (SP) particles in the soil samples. From the results of multivariate statistical analyses, the sources ofidentified heavy metals were classified as anthropogenic sources(Cr, Cu, Pb, As, and Zn),natural sources(V, Mn, Fe, Ni, and Sr ),and intermediate sources (Al and Cl).

Deciphering the Driving Mechanism and Regulatory Strategies of Antibiotic Resistance Genes Transmission in Lead-Contaminated Soil Microbial Communities by Multiple Remediation Methods

Pb-contaminated soil poses inherent risks for the spread of antibiotic resistance genes (ARGs). However, few reports have investigated the distribution of lead resistance genes (LRGs), particularly their role in ARGs dynamics during Pb-contaminated soil remediation. This study explored the mechanisms driving ARGs variation under different remediation strategies. The results indicated that an increase in the total abundance of ARGs after applying montmorillonite (Imvite), the composite remediation agents of MgO and Ca(H2PO4)2 (MgO-Ca(H2PO4)2), and the composite remediation agents of montmorillonite, MgO, and Ca(H2PO4)2 (Imvite-MgO-Ca(H2PO4)2). Bioelectrochemical systems (BES) effectively reduced ARGs abundance, and when combined with Imvite-MgO-Ca(H2PO4)2, lowered the risk of ARGs proliferation linked to antibiotic deactivation. Changes in Pb concentration and pH reshaped microbial communities, impacting both LRGs and ARGs. To reduce the risk of ARGs proliferation and transmission during, various control strategies, such as modifying Pb stress, adjusting pH, and manipulating microbial community structure, have been proposed. The study provided theoretical foundation and practical strategies for controlling ARGs dissemination during the remediation of heavy metal-contaminated soil.

Health risk assessment of toxic metals and DNA damage in somatic and germ cells by soil and groundwater of a major cement factory in Nigeria.

The waste generated from cement manufacturing is an important source of heavy metal contamination of groundwater and soil. This study investigated the concentration of toxic metals in the soil of a major cement factory and nearby groundwater. Ecological and carcinogenic risks of the metals were calculated. Potential reproductive toxicity and genotoxic effects of the samples were assessed in sex and somatic cells of male mice using sperm abnormalities and bone marrow micronucleus (MN) assays, respectively. Also, the serum ALP, ALT, AST, Total Testosterone (TT), Luteinizing Hormone (LH), and Follicle Stimulating Hormone (FSH); and liver SOD and CAT activities were measured in the treated mice. Cr, Cu, Ni, Zn, Mn, Cd, and Pb levels in the soil and groundwater exceeded the allowable maximum standard. Ingestion and dermal contact were the most probable routes of human exposure with children having about three times higher probability of exposure to the metals than the adults. Ni, Pb, and Cr presented carcinogenic risks in children and adults. In the MN result, nuclear abnormalities in the studied mice especially micronucleated polychromatic erythrocytes increased significantly (p < 0.05). Compared to the negative control, the ratio of PCE/NCE showed the cytotoxicity of the two samples. Data further showed a significant increase in the serum ALP, AST, and ALT while the liver CAT and SOD activities concomitantly decreased in the exposed mice. Sperm morphology result showed that the samples contained constituents capable of inducing reproductive toxicity in exposed organisms, with alterations to the concentrations of TT, LH, and FSH. Toxic metal constituents of the samples were believed to induce these reported reproductive toxicity and genotoxic effect. These results showed the environmental pollution caused by cement factory and the potential effects the pollutants might have on exposed eukaryotic organisms.

Assessing heavy metal contamination in roadside soils as a consequence of motor vehicle emissions

Assessing heavy metal contamination in roadside soils as a consequence of motor vehicle emissions

The fate of Cd in Soils with Various Particle Sizes: Characteristics, Speciation Distribution and Influencing Factors.

This study investigated the distribution of Cd in soil water-stable aggregate particles of varying sizes, revealing that smaller particles have higher total Cd content as well as different forms of Cd content, with the clay particle showing a greater tendency to accumulate Cd. However, the proportion of high activity Cd is lower in clay particles, posing a lower environmental risk of Cd transformation compared to silt particles. Adsorption experiments indicated that the clay particle exhibits the strongest adsorption capacity and highest adsorption rate. Additionally, correlation and principal component analyses identified Fe-Mn oxides and organic matter as the primary influencing factors on Cd distribution characteristics, with pH playing a secondary role. These findings provide valuable insights for the remediation of heavy metal-contaminated soil.

Exopolysaccharide-Producing Bacteria Regulate Soil Aggregates and Bacterial Communities to Inhibit the Uptake of Cadmium and Lead by Lettuce

The accumulation of heavy metals in the soil not only causes serious damage to the soil ecosystem, but also threatens human health through the food chain. Exopolysaccharides have the functions of adsorbing and chelating heavy metals and reducing their bioavailability in the soil. In our study, exopolysaccharide-producing bacteria with a high efficiency in adsorbing cadmium (Cd) and lead (Pb) were screened from heavy metal-contaminated farmland. Through pot experiments, the influence of functional strains on the size distribution, heavy metal content, and bacterial community structure of soil aggregates in lettuce was studied using high-throughput sequencing technology. The results show that 11 strains secreting exopolysaccharides were initially screened from heavy metal-contaminated soil. Among them, strain Z23 had a removal rate of 88.6% for Cd and 93.2% for Pb. The rate at which Cd was removed by strain Z39 was 92.3%, and the rate at which Pb was removed was 94.4%. Both strains belong to Bacillus sp. Strains Z23 and Z39 induced the formation of Fe2Pb(PO4)2, Cd2(PO4)2, and Pb2O3 in the solution. The pot experiments showed that strains Z23 and Z39 increased (19.1~23.9%) the dry weight and antioxidant enzyme activity of lettuce roots and leaves, while reducing (40.1~61.7%) the content of Cd and Pb. Strains Z23 and Z39 increased the proportion of microaggregates (&lt;0.25 mm) and the content of exopolysaccharides in rhizosphere soil and reduced (38.4–59.7%) the contents of available Cd and Pb in microaggregates, thus inhibiting the absorption of heavy metals by lettuce. In addition, the exopolysaccharide content and the bacterial community associated with heavy metal resistance and nitrogen (N) cycling (Patescibacteria, Saccharimonadales, Microvirga, and Pseudomonas) in microaggregates were key factors affecting the available heavy metal content in soil. These results show that the exopolysaccharide-producing bacteria Z23 and Z39 reduced the absorption of Cd and Pb by lettuce tissues, thus providing strain resources for the safe utilization of soils that exceed heavy metal standards for farmland and for reducing the heavy metal content in vegetables.

Predicting increments in heavy metal contamination in farmland soil

Predicting increments in heavy metal contamination in farmland soil

Unveiling heavy metal(loid) contamination and migration at an abandoned smelting site: Integrated geophysical and hydrological analyse

The heavy metal contamination at abandoned smelting sites is receiving increasing attention. This study focuses on an abandoned lead–zinc smelting site and uses several methods (such as soil sampling, geophysical exploration, and groundwater monitoring) to systematically investigate the contamination characteristics, distribution patterns, and migration mechanisms of heavy metal(loid) in soil and groundwater. A geological structure model of the study area was established through drilling data and geophysical techniques (Ground penetrating radar (GPR) and Electrical resistivity tomography (ERT)), revealing the relationships among soil resistivity, electromagnetic wave reflection characteristics, and geological structure. This study revealed that heavy metal contamination in soil was concentrated mainly northwest of the site and was closely related to historical smelting activities. The presence of heavy metal(loid)s in groundwater had a complex correlation with soil physicochemical properties and environmental elements, and its distribution was influenced by both hydrogeological conditions and soil properties. This study also investigated the effects of the soil water content (SWC) and soil hydraulic conductivity (Ks) on heavy metal(loid)s migration and reported that high SWC and Ks contribute to the dissolution and migration of heavy metals. In addition, a 3D visualization model of heavy metal contamination plumes was established via Voxler software. This model intuitively demonstrated the migration and diffusion of heavy metal(loid)s in the underground environment, offering a novel perspective on their subsurface behavior. The research results provide important information for understanding the migration of heavy metal(loid)s in soil-groundwater systems.

Arsenic and Heavy Metals in Soils and Plants near Sulfide Mines: Implications for Phytoremediation and Phytomanagement.

The accumulation of heavy metals (i.e., As, Cu, Ni, Pb, and Zn) in soils and native plant species near copper, nickel, and pyrite mines in Vietnam was assessed. The highest soil As, Cu, Ni, Pb, and Zn concentrations recorded in mine soils were 42.3, 1570, 9870, 128, and 462 mg/kg, and those in agricultural soils were 11.4, 453, 94.9, 34.4, and 147 mg/kg, respectively. Pollution index (PI) values indicated heavy pollution (PI = 3.99-13.0) for mine soils, and unpolluted to severely polluted (PI = 0.65-2.84) for agricultural soils. Soil enrichment factors had a wide range, from minimal to extreme enrichment of heavy metals (EF = 0.03-91.4). Arsenic minerals may be the main source of high As concentrations in sulfide mines. The As, Cu, Ni, Pb, and Zn concentrations of 20 native plant species near three mines were in the ranges of 0.05-1150, 3.17-123, 0.47-291, 0.08-6.34, and 6.87-168 mg/kg (dry weight, DW), respectively. Based on the recorded hyperaccumulation levels (1150 mg/kg, DW), bioaccumulation factors (BAF = 2.4-90.0), biomass, and rapid growth, Pteris vittata L. is considered a promising plant for phytoextraction of As in soils. Bidens pilosa L. has potential for phytostabilization of sulfide-bearing soils, given its low concentrations of heavy metals in plant shoots, BAF values of <1, high biomass, and wide distribution. Integrated phytoremediation and phytomanagement are applicable to metal-contaminated soils. Phytomining, energy crops, and vegetation cover should be investigated for the phytomanagement of metal-contaminated soils in mining areas.

Potential to Ensure Safe Production of Water Spinach in Heavy Metals-Contaminated Soil by Substituting Chemical Fertilizer with Organic Fertilizer

Organic fertilizers are widely used to improve soil quality. However, their potential for ensuring the safe production of vegetables in soils with varying levels of heavy metals pollution remains inadequately explored. Here, we conducted a pot experiment to investigate the effects of substituting chemical fertilizers with organic fertilizer on the HMs accumulation in water spinach by simulating soils with different levels of HMs pollution. The results showed that the organic fertilizer significantly increased the soil pH, cation exchange capacity (CEC), and organic matter (OM). Furthermore, it led to a reduction in the soil DTPA–Cd and DTPA–Pb levels by 3.3–20.6% and 22.4–47.3%, respectively, whereas the DTPA–As levels increased by 0.07–7.7 times. The organic fertilizer effectively reduced the Cd and Pb content in water spinach below the safety limits when the added Cd content in the soil was less than 2 mg/kg and the Pb content was equal to or less than 90 mg/kg. However, its efficacy in reducing As accumulation in water spinach was limited, emphasizing the need for caution when using organic fertilizers in As-contaminated soils. Our results provide valuable insights for the scientific and precise utilization of organic fertilizers, thereby contributing to the safe production of vegetables.

Ameliorating arsenic and PVC microplastic stress in barley (Hordeum vulgare L.) using copper oxide nanoparticles: an environmental bioremediation approach

The present study investigates the impact of varying concentrations of PVC microplastics (PVC–MPs) – specifically 0 (no PVC–MPs), 2, and 4 mg L− 1 –alongside different arsenic (As) levels of 0 (no As), 150, and 300 mg kg− 1 in the soil, with the concurrent application of copper oxide–nanoparticles (CuO–NPs) at 0 (no CuO –NPs), 25 and 50 µg mL− 1 to barley (Hordeum vulgare L.) plants. This research primarily aims to assess plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators, as well as the response of various antioxidants (both enzymatic and non-enzymatic) and their relevant genes expression, proline metabolism, the AsA–GSH cycle, and cellular fractionation within the plants. The findings showed that increased levels of PVC–MPs and As stress in the soil significantly reduced plant growth and biomass, photosynthetic pigments, and gas exchange characteristics. Additionally, PVC–MPs and As stress increased oxidative stress in the roots and shoots, as evidenced by elevated levels of malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL), which in turn stimulated the production of various enzymatic and non-enzymatic antioxidants, gene expression, and sugar content. Furthermore, a notable increase in proline metabolism, the AsA–GSH cycle, and cellular pigmentation was observed. Conversely, the application of CuO–NPs resulted in a substantial improvement in plant growth and biomass, gas exchange characteristics, and the activity of enzymatic and non-enzymatic antioxidants, along with a reduction in oxidative stress. Additionally, CuO–NPs enhanced cellular fractionation while decreasing proline metabolism and the AsA-GSH cycle in H. vulgare plants. These outcomes provide new insights into sustainable agricultural practices and offer significant potential in addressing the critical challenges of heavy metal contamination in agricultural soils.

The roles of nanoparticle-enriched biochars in improving soil enzyme activities and nutrient uptake by basil plants under arsenic toxicity

Enriched biochar with improved properties and functionality can play a significant role in providing sustainable solutions for mitigating heavy metal contamination in soil. In this experiment, the effects of solid and enriched biochars (potassium-enriched biochar (BC-K), magnesium-enriched biochar (BC-Mg), both individually and combined) were examined on soil microbial and enzyme activities, as well as nutrient uptake by basil plants cultivated in a soil with three levels of arsenic (nontoxic, 50 mg As kg−1 soil, and 100 mg As kg−1 soil). Biochar-related treatments, increased soil organic matter (65–76%), while decreased availability of arsenic (6–55%) in the soil. The microbial biomass carbon (by about 123%) and soil basal respiration (by about 256%), and soil enzymatic activities (β-glucosidase, urease, alkaline phosphatase, and dehydrogenase) were enhanced by enriched biochars under arsenic toxicity. The solid and particularly enriched biochars decreased arsenic content and improved nitrogen and phosphorus contents of roots and shoots, root length, root activity, and root and shoot biomass in basil plants. Therefore, it is conceivable to suggest that enriched biochars are superior treatments for improving nutrient absorption rates and basil growth under arsenic toxicity through decreasing arsenic mobility and increasing soil microbial activities.

Source-oriented stochastic health risk assessment of toxic metals in soil via a hybrid model and Monte Carlo simulation

Toxic metal contamination in soils poses significant hazards to the environment and human health; thus, quantitative assessment of the sources and risks of metal contaminants are urgently needed. A hybrid model that integrates the positive matrix factorization (PMF) and random forest (RF) methods was proposed to quantify the sources of toxic metals in soils by combining diverse environmental variables (source proxies) in this study. In addition, a health risk assessment and Monte Carlo simulations were integrated to estimate the source-oriented stochastic health risk. The results suggested that, except for Ni, which exhibited moderate contamination, other toxic metals (As, Cd, Cr, Hg and Pb) presented slight contamination. Four sources (agricultural activities loaded heavily by As, atmospheric deposition loaded heavily by Hg and Pb, natural sources and mining activities loaded heavily by Cr and Ni, and industrial activities loaded heavily by Cd) were defined and explained 23.44 %, 26.65 %, 30.13 % and 19.78 % of the total variance in toxic metals, respectively. The principal route of exposure (i.e., ingestion), the population at highest risk (i.e., children), and the most hazard-inducing metals (i.e., As and Cr) were determined. Agricultural activities and the combination of natural sources and mining activities demonstrated certain degrees of noncarcinogenic risk to children, with exceedance ratios of 2.20 % and 2.56 %, respectively. Additionally, the combination of natural sources and mining activities demonstrated probabilities for significant carcinogenic risk to adults and children of 0.59 % and 3.76 %, respectively. To reduce the health risks of toxic metals in soils and to protect food and ecological safety, strict regulations should be established to control the discharge of waste from mining and agricultural activities.

Assessment of heavy metal contamination and accumulation in soil and leafy vegetables collected from industrial belt in Bharuch district, Gujarat

Assessment of heavy metal contamination and accumulation in soil and leafy vegetables collected from industrial belt in Bharuch district, Gujarat

Spatial and Bioaccumulation of Heavy Metals in a Sheep-Based Food System: Implications for Human Health.

Heavy metal contamination in agricultural soils presents serious environmental and health risks. This study assessed the bioaccumulation and spatial distribution of nickel, cadmium, zinc, lead, and copper within a sheep-based food chain in the Baia Mare region, Romania, which includes soil, green grass, sheep serum, and dairy products. Using inductively coupled plasma mass spectrometry (ICP-MS), we analyzed the concentrations of these metals and calculated bioconcentration factors (BCFs) to evaluate their transfer through trophic levels. Spatial analysis revealed that copper (up to 2528.20 mg/kg) and zinc (up to 1821.40 mg/kg) exceeded permissible limits, particularly near former mining sites. Elevated lead (807.59 mg/kg) and cadmium (2.94 mg/kg) were observed in industrial areas, while nickel and cobalt showed lower concentrations, but with localized peaks. Zinc was the most abundant metal in grass, while cadmium transferred efficiently to milk and cheese, raising potential health concerns. The results underscore the complex interplay between soil properties, contamination sources, and biological processes in heavy metal accumulation. These findings highlight the importance of continuous monitoring, risk assessment, and mitigation strategies to protect public health from potential exposure through contaminated dairy products.

Aqueous and Colloidal Dynamics in Size-Fractionated Paddy Soil Aggregates with Multiple Metal Contaminants under Redox Alternations.

Soil contamination by multiple metals is a significant concern due to the interlinked mobilization processes. The challenges in comprehending this issue arise from the poorly characterized interaction among different metals and the complexities introduced by spatial and temporal heterogeneity in soil systems. We delved into these complexities by incubating size-fractionated paddy soils under both anaerobic and aerobic conditions, utilizing a combination of techniques for aqueous and colloidal analysis. The contaminated paddy soil predominantly consisted of particles measuring <53, 250-53, and 2000-250 μm, with the <53 μm fractions exhibiting the highest concentrations of multiple metals. Interestingly, despite their higher overall content, the <53 μm fractions released less dissolved metal. Furthermore, glucose enhanced the release of arsenic while simultaneously promoting the sequestration of other metals, such as Pb, Zn, and Cu. Utilizing asymmetric flow field-flow fractionation, we unveiled the presence of both fine (0.3-130 kDa) and large (130-450 nm) colloidal pools, each carrying various metals with different affinities for iron minerals and organic matter. Our results highlighted the pivotal role of the <53 μm fraction as a significant reservoir for multiple metal contaminants in paddy soils, in which the colloidal metals were mainly associated with organic matter. These findings illuminated the size-resolved dynamics of soil metal cycling and provided insights for developing remediation strategies for metal-contaminated soil ecosystems.

Sustainable Stabilizer Derived from Calcium- and Phosphorus-Rich Biowaste for Remediation of Heavy Metal-Contaminated Soil: A Critical Review

Soil pollution by heavy metals (HMs) is a major environmental problem around the world. The addition of biowaste-based stabilizers for HM remediation has recently gained attention due to its relatively low cost and eco-risk, abundance, ease of operation, and quick remediation results. Among these stabilizers, shell (crustacean shell, bivalve shell, and eggshell), starfish, and bone-based stabilizers are particularly attractive because of their high Ca and P contents, allowing for highly efficient HM immobilization and simultaneous supplement of nutrients to the soil. However, a comprehensive review focusing on these stabilizers is currently missing. Therefore, this review attempts to summarize the HM immobilization efficiency of these stabilizers and the mechanisms associated with HM stabilization, and perform an operation cost estimation and cost comparison. Cost comparisons among different stabilizers are widely ignored in reviews due to the lack of reliable cost estimation tools or methods. However, for practical application in soil remediation, cost is one of the most important factors to consider. Thus, a simple but reasonable cost estimation method is developed and discussed in this review. Bivalve shell-based stabilizers demonstrated the most promising results for the immobilization of soil HMs in terms of higher performance and lower cost. Current research limitations, challenges, and recommendations regarding possible future research directions are also provided.

Investigating the Interactive Effect of Arbuscular Mycorrhizal Fungi and Different Chelating Agents (EDTA and DTPA) with Different Plant Species on Phytoremediation of Contaminated Soil

Heavy metal (HM) contamination in soil poses a severe environmental threat, jeopardizing ecosystem health and potentially entering the food chain through plant uptake. Phytoremediation, a bioremediation technique utilizing plants to remove or immobilize contaminants, offers a sustainable and eco-friendly solution for HM remediation. This study investigated the interactive effects of arbuscular mycorrhizal fungi (AMF) and chelating agents (EDTA and DTPA) on the growth of maize (Zea mays L.) and alfalfa (Medicago sativa L.) cultivated in metal-contaminated soil and their impact on HM uptake by these plants. The findings revealed that AMF and chelating agents have complex interactive effects on plant growth and metal accumulation. Maize (Zea mays L.) shoot dry matter increased with AMF and chelating agents at lower concentrations. Both plants generally showed a significant (p ≤ 0.05) increase in shoot dry matter with amendments, with AMF × EDTA (10 mmol/kg) being the most effective for alfalfa. DTPA and EDTA generally reduced the DTPA-extractable metals in soil, suggesting potential for metal removal. However, the effects of AMF on metal availability were variable. Metal concentrations in maize (Zea mays L.) shoots increased with increasing DTPA and EDTA concentrations, while the effects of AMF were more complex. The alfalfa shoot metal content showed varied responses, with EDTA (5 mmol/kg) effectively reducing the metal uptake. In general, treatments involving chelating agents (DTPA and EDTA) tend to result in higher bioaccumulation factor (BF) values compared to the non-treated controls for most HMs in both plant species. Mycorrhizal fungi (AMF) treatment alone or in combination with chelating agents also showed that varied effects on HM uptake in both the alfalfa and maize treatments with chelating agents, especially at higher concentrations, generally promoted the greater translocation of HMs in both plant species. Both alfalfa and maize responded differently to treatments, with some treatments showing higher translocation factor (TF) values for certain HMs in one species compared to the other. Mycorrhizal fungi (AMF) treatment alone or in combination with chelating agents also showed varied effects on HM uptake and translocation in both alfalfa and maize. Further research is required to optimize remediation strategies that balance plant health and metal mobilization.

Rice husk biochar is more effective in blocking the cadmium and lead accumulation in two Brassica vegetables grown on a contaminated field than sugarcane bagasse biochar.

Heavy metal-contaminated soil has a great impact on yield reduction of vegetable crops and soil microbial community destruction. Biochar-derived waste biomass is one of the most commonly applied soil conditioners in heavy metal-contaminated soil. Different heavy metal-contaminated soil added with suitable biochars represent an intriguing way of the safe production of crops. This study investigated the effects of two types of biochar [rice husk biochar (RHB) and sugarcane bagasse biochar (SBB)] on Cd and Pb accumulation in Shanghaiqing (SHQ, a variety of Brassica campestris L.) and Fengyou 737 (FY, a variety of Brassica napus), as well as on the soil microbial community, through a field experiment. RHB and SBB were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmet-Teller method. The results showed that RHB and SBB displayed the higher pH, cation exchange capacity and pore properties, and the addition of RHB and SBB enhanced soil pH and rhizosphere microorganisms promoting vegetables yield. RHB treatments were more effective than SBB in reducing upward transfer of Cd and Pb, blocking the accumulation of Cd and Pb in the edible parts of SHQ and FY, and decreasing soil Cd and Pb bioavailability. Additionally, RHB and SBB changed the composition of the rhizosphere soil microbial community. The application of biochar promoted the growth of ecologically beneficial bacteria (Nitrospira, Opitutus, and Gemmatimonas) and fungi (Mortierella and Holtermanniella), whereas reducing the enrichment of plant pathogenic fungi (Alternaria, Stagonosporopsis, Lectera, and Periconia) in rhizosphere soil. Our findings demonstrated that the application of RHB significantly reduces Cd and Pb accumulation in the edible parts by decreasing the soil Cd and Pb bioavailability and altering the rhizosphere microbial community composition in two Brassica vegetables grown on Cd/Pb-contaminated soils. Thus, the application of two biochar, especially RHB is a feasible strategy for the safe production of vegetable crops in Cd/Pb co-contaminated soils.

B-277 Detectable Levels of Toxic Metals in Children's Playgrounds

Abstract Background Metal-contaminated soil poses significant health risks to kids because they are more sensitive to heavy metal exposure in the environment. Studies have shown that continuous exposure to metals can increase the risk of metal accumulation in blood and various body organs. This study determines the levels of some toxic metals in various playgrounds in our community. Methods We determined the levels of lead (Pb), chromium (Cr), cadmium (Cd), and copper (Cu) in six playgrounds (parks) (T-RP, T-GP, T-TX, L-HH, L-WH, L-SPLX) using graphite furnace atomic absorption spectrophotometry (GF-AAS) technique. Soil samples were collected at least one foot below the soil surface, and metal was extracted using ultra-pure nitric before analysis using GF-AAS. Data were analyzed using analysis of variance (ANOVA). Results The results showed significant detectable levels of the metals in all playgrounds evaluated in this study. L-WH Park in League City has the highest detectable levels of Pb (12.43 ± 46 mg/Kg, P&amp;lt;0.05) compared to other children playgrounds examined in this study (T-RP (3.93 ± 3.97 mg/Kg), T-GP (7.09 ± 2.79 mg/Kg), T-TX (6.05 ± 1.92 mg/Kg), L-HH (4.68 ± 0.76 mg/Kg), L-SPLX (2.64 ± 1.63 mg/Kg). The concentration of detectable cadmium in T-RP park (0.16 ± 0.11 mg/Kg) was significantly higher than all the other five children's playgrounds studied L-WH (0.02 ± 0.01 ), T-GP (0.05 ± 0.04 mg/Kg), T-TX (0.02 ± 0.01 mg/Kg), L-HH (0.04 ± 0.01 mg/Kg), L-SPLX (0.09 ± 0.04 mg/Kg) (P&amp;lt;0.05). Conclusions The playgrounds contain detectable toxic metals that might pose health risks to children in the community. Though the lead levels are below the CDC-recommended lead soil concentration in urban areas, they still pose health risks to children in the environment when continuously exposed to the playground. The concentrations of Cu and Cr were not statistically different among the playgrounds. The detection of Pb and Cd highlights the potential health risks to children. Overall, this study shows that metal levels in playgrounds should be public information available to parents.