Soil Zn Concentrations Research Articles

Predicting the Zinc Content in Rice from Farmland Using Machine Learning Models: Insights from Universal Geochemical Parameters

Zinc (Zn) is an essential nutrient for the human body and is prone to deficiency. Supplementing Zn through zinc-enriched cereals is of great significance in addressing the widespread issue of zinc deficiency. However, there is no simple linear correlation between the soil zinc content and rice grain zinc content, which poses challenges for zoning zinc-enriched rice cultivation based on the soil Zn content. Therefore, accurately predicting the zinc content in rice grains is of great importance. To verify the robustness of the prediction model and expand its applicability, this study established a prediction model using 371 sets of previously collected and tested rice grain and root zone soil samples from the Pearl River Delta and Heyuan regions in Guangdong. The model was validated using the data from 65 sets of rice and root zone soil samples collected and analyzed in Zijin and Dongyuan counties, Heyuan, in 2023. The results show that zinc absorption by rice grains is controlled by multiple factors, primarily related to the soil S, P, CaO, Mn, TFe2O3, TOC, and SiO2/Al2O3 ratio. Both the artificial neural network model and random forest model demonstrated a good predictive performance across large regions. However, in the Heyuan region, the random forest model outperformed the artificial neural network model, with an R2 of 0.79 and an RMSE of 0.05 when the predicted data were compared against the measured BAFZn of the rice. This suggests that predicting the zinc content in rice grains based on the soil macro-elements (including oxides) and TOC is feasible, and, within certain regional boundaries, the prediction model is robust and widely applicable. This study provides valuable insights into the rational development of zinc-enriched rice in the Heyuan region and offers a useful reference for establishing prediction models of the beneficial element content in rice grains in areas with limited data.

Health Risk of Heavy Metal and Implication for Ecological Threat in Soils Weathered from the Black Shale.

Heavy metals were analyzed in rhizosphere soils and rice grains collected from typical black shale areas. The concentrations of As, Cd, Cu, and Zn in the rhizosphere soil exceeded the current soil environmental quality standards. Cd exhibited the highest bioaccumulation capacity, with 45% of rice grains exceeding food safety limit. Structural equation modeling (SEM) revealed that soil organic matter indicated that 34.79% of rice Cd accumulation and approximately 10%-25% of other metals were inhibited. Multiple regression modelling showed that in areas with high geological background of black shales, the screening and intervention values for soil Cd were adjusted to 0.24mg kg-1 and 0.42mg kg-1 for pH ≤ 5.5 and 0.27mg kg-1 and 1.66mg kg-1 for pH 5.5 - 6.5 respectively. Primary exposure pathways for non-carcinogenic risks were identified as food ingestion and skin contact. This study provides fundamental information for land use application and development in region with high geological background.

Assessment of the interaction of copper and zinc with cadmium to reduce its toxicity in heavy metal-contaminated river basin soils

Copper (Cu) and zinc (Zn) serve a dual purpose by providing essential nutrients to plants and reducing cadmium (Cd) toxicity in the soil–plant system. Using Cu and Zn to alleviate Cd toxicity could be an effective and low-cost method for rehabilitating contaminated soils. Two laboratory incubation experiments were conducted to study the interaction mechanisms between Cd and Cu, and Cd and Zn at different application levels in metal-contaminated Typic Haplaquept soil. In the first experiment, 2 g of soil were placed in wide-mouthed test tubes in duplicate, with four levels of Cd (0, 1, 2, and 5 mg kg−1) and four levels of Cu (0, 5, 10, and 20 mg kg−1) added simultaneously. The second experiment used the same levels of Cd with four levels of Zn (0, 5, 10, and 20 mg kg−1). The samples were kept at 50% field water holding capacity and incubated for 0, 7, 15, 30, and 60 days at room temperature (26 ± 1 °C). The study results showed that increasing doses of Cu or Zn significantly and consistently reduced the extractable Cd and increased the soil Cu or Zn content. Over time, a significant reduction in extractable Cd and Zn and an increase in Cu in the soil were observed. Cd concentrations exhibited a gradual decline of 71.8%, 70.2%, 69.8%, and 73.5% at Cu levels of 0, 5, 10, and 20 mg kg⁻1, and 69.2%, 69.6%, 68.0%, and 70.1% at Zn levels of 0, 5, 10, and 20 mg kg⁻1, respectively, averaging a 71.3% and 69.2% reduction over an incubation period from 0 to 60 days. The interactions of Cd with Cu, Cd with Zn, Cu with days, Zn with days, and Cd with days significantly decreased Cd and Zn and increased Cu contents in the soil. The interactions between Cd and Cu, and Cd and Zn in the soil were antagonistic, demonstrating that applying Cu and Zn to the soil effectively counteracted Cd toxicity, supporting healthy plant growth in Cd-contaminated soil. It can be useful in reducing heavy metal pollution in the soils providing a sustainable and economical approach with ramifications for the environment. Using antagonistic interaction of Cd with essential micronutrients such as Cu and Zn, it contributed to soil restoration, diminished bioavailability of toxic metals and further raised the potential for safer agricultural practices in contaminated locations.

Analysis of Heavy Metal Content of Mn, Cu, Fe, Zn, Pb in Agricultural Irrigation Water and Soil After Tin Mining

Abstract The content of heavy metals Mn, Cu, Fe, Zn, and Pb in agricultural irrigation water and precast tin mining soil revealed that heavy metal concentration levels had exceeded the safe limit according to health standards. The concentration of these heavy metal coils affects plant growth and the quality of agricultural products. Analysis methods used include atomic absorption spectrophotometer and flame emission spectrometry. Data collection from various literature sources that discussed the content of heavy metals in the former tin mine area. The study revealed Mn, Cu, Fe, and Zn in water and agricultural rice field soil according to the quality standard, and the Pb level in irrigated water and soil was quite high, more than 0.1 mg/L, exceeding the limit set by the quality standard. High heavy metal concentrations in post-tin mining areas can endanger human health and the environment. Comprehensive recovery efforts are needed to reduce the content of heavy metals in post-tin mining farmland so that water and soil quality can be improved.

Assessing Environmental Risks of Local Contamination of Garden Urban Soils with Heavy Metals Using Ecotoxicological Tests.

Heavy metal soil contamination in urban areas poses a significant environmental hazard, particularly in regions with historical or ongoing industrial activities. These areas are often polluted with metals such as Pb, Cu, Cd, and Zn, which can be absorbed by plants and pose risks to both ecosystems and human health. This study investigates soil contamination in urban gardens in Wroclaw, Poland, where elevated levels of trace elements were detected. Standard soil analyses, including macroelement content, granulometry, and trace element concentrations, were performed alongside an ecotoxicological evaluation using an Ostracodtoxkit test. The test evaluates the impact of contaminants on organism growth. An uncontaminated urban garden soil served as a reference. This study revealed that Zn, Cu, Pb, and Cd concentrations in soils exceeded limits permitted by Polish regulations in several soil samples. Despite the high concentrations of total metals, the bioavailable forms of these metals (measured by extraction of 1 M NH4NO3 extraction) were significantly lower, highlighting that the total metal content may not fully reflect the environmental risk. Pb was identified as the primary contributor to growth inhibition of test organisms, showing a particularly strong correlation with ecotoxicity. These findings underscore the importance of using ecotoxicological tests to evaluate soil contamination risks.

The Effects of Heavy Metals on Enzyme Activity and Microbial Biomass of the Soil Around the Waste Disposal Site (Case Study of Saravan - Iran)

ABSTRACT Municipal solid waste is considered an environmental threat in Iran. The study was performed on soil near the Saravan dumpsite and measured the concentrations of 8 metals (Zn, Cu, As, Hg, Pb, Cr, Cd, and Ni) in soil, by inductively coupled plasma mass spectrometry. The average content of As, Cu, Cr, Pb, Zn, Hg, Ni, and Cd in soil were 10.48, 20.22, 19.07, 24.95, 28.83, 0.13, 19.91, and 0.1 mg/kg, respectively. The mobility factors based on water-soluble and exchangeable fractions were As (8.85%), Zn (4.19%), Pb (1.85%), Cu (1.60%), and Cr (0.02%), and not detectable for Hg, Ni, and Cd. Evaluation of metals contamination by pollution index, integrated pollution index, and Nemerowʼs pollution index for each metal showed that PI for all metals except Hg was in the range of low to moderate, and for Hg, 50% in high pollution grade; the average of the IPI (1.21), indicated a moderate pollution condition; the mean value of the PINemerow (1.20), which was in slight pollution grade. The correlations between total concentrations of metals, and bioavailable fractions with microbial biomass carbon, basal respiration, microbial quotient, metabolic quotient, urease, and alkaline phosphatase activities were moderate (r = 0.4-0.6). The activity of urease was from 37.79 to 1414.31 µg N gˉ1 dm.2 hˉ1 and alkaline phosphatase from 34.66 to 698.78 µg nitrophenyl gˉ1 dm. hˉ1. Due to the rainy climate and the continuous leaching of the surface soil, we suggested performing waste separation and the treatment of leachate produced before flowing downstream.

Assessment of Selected Heavy Metals Content in Soil and Rice Grown on Farmland around Edozhigi River in Niger State, Nigeria

The global climate continues to deteriorate, resulting in excessive carbon emissions, heavy metal pollution possesses serious threats to human life and modern civilization. The concentration of Zn, Fe, Cr, Pb, Cu and Cd in soil and rice grown in two locations (A and B) AROUND Edozhigi river were determined using standard methods og analysis. Results obtained for location A, indicate high concentration of Zn 9.75±0.55, 9.61±0.54, 1.03±0.58 and 1.69±0.66 mg/kg in soil, root, stem and seed of rice plant respectively. The order of Zn concentration of Zn metal in location B is 2.07±0.55 (soil) > 1.70±0.54 (root) > 1.67±0.58 (stem) > 1.27±0.66 (seed). Concentration of Fe (mg/kg) in soil (25.50±0.00) and root (26.32±0.00) from location B were significantly higher than those of stem (8.46±0.00 mg/kg) and seed (6.98±0.00 mg/kg) respectively. Concentration of Cu (mg/kg) in soil, root, stem and seed from location A and B were between 0.00±0.00 - 0.03±0.40 mg/kg respectively. The low concentration of these metals in soil around Edozhigi river makes the soil fit for growing crops.

Research on heavy metal enrichment and transportation in tea plant-soil systems of different varieties.

This study aimed to investigate heavy metal enrichment in different tea plant varieties and their distribution within different plant parts and to clarify the behavioral characteristics of heavy metals in the tea tree-soil system and their influencing factors. In this study, soil samples were collected from the root zones of 13 tea tree varieties in Guizhou, which had been planted for 10years. The aim was to compare the physicochemical properties of tea plantation soils under soil-forming matrixes and consistent management. Additionally, the study investigated the enrichment and transportation patterns of Cd, Cr, Cu, Pb, Zn, and Ni in the tea tree-soil systems of different tea tree varieties. The results showed that the planting of tea trees decreased the soil pH by 0.5; soil nutrients decreased; soil Pb, Cr, Ni, Cu, and Zn contents in the root zone increased; and Cd content decreased. Heavy metals were mainly enriched in the roots, and Zn, Cu, Ni, and other elements related to the protein and enzyme synthesis of tea trees could be mostly transported to the stems and leaves. There were significant differences in the enrichment and transportation of heavy metals among the different tea tree varieties. Under consistent soil-forming parent material, soil pH, organic matter, nutrients, and other indices only had a significant effect on heavy metal enrichment in the tea tree roots. Therefore, in areas with high background soil heavy metal contents, the construction of tea plantations should be based on regional soil environmental conditions to choose tea tree varieties with low heavy metal enrichment capacities to avoid the risk of high background soil heavy metals on the safe production of tea for consumers.

EFFECT OF MUNICIPAL SOLID WASTE COMPOST, GYPSUM AND MYCORRHIZA ON METALS CONTENT IN SOIL AND PEANUT GRAIN

Municipal solid waste compost (MSWC) is widely used as an organic soil amendment and fertilizer on agricultural land. However, applying MSWC can cause adverse effects due to the heavy metals contained. This study aimed to determine the heavy metal content of MSWCs in the presence of mycorrhizae and gypsum and their effects on soil and peanut grain. The field experiment was conducted using a split factorial design based on a Randomized Complete Block Design (RCBD) with three replications in Iran during 2018 and 2019. The main factor includes two levels of gypsum (0 and 150 kg ha-1) and the sub-factors include the presence and absence of Arbuscular mycorrhizal fungi (AMF) and different levels of MSWC at five levels (0, 2, 4, 6, and 8 t ha-1). The findings showed that MSWC significantly increased the concentrations of manganese (Mn), lead (Pb), nickel (Ni), zinc (Zn), cobalt (Co), chromium (Cr), cadmium (Cd), and boron (B) in soil and grains. In addition, Co, Ni, and Zn concentrations in grain increased and Pb, Mn, Ni, and Zn concentrations in soil decreased with AMF application. Gypsum treatment also had no significant effect on metals in both grain and soil. According to the obtained results, the use of 4 t ha-1 of MSWC along with mycorrhiza in peanut cultivation is suggested in order to reduce the environment risks of soil and plants cause by the use of compost, and also use the benefits of urban waste compost.

Insights into Martian bedform migration: Results from Gale, Jezero and Pasteur craters

AbstractAn attempt is made in this study to advance the understanding of the sand movement on Mars by studying the bedform migration at Gale, Jezero and Pasteur craters. The study on the grain size distribution at Gale Crater using Curiosity rover (MAHLI and APXS) observations reveals that the grains with smaller diameters (~50–150 μ) are more prone to migration and vice‐versa, which gives an idea of the necessary requirements that initiate bedform migration. The chemical analysis of the surface materials at the Gale crater revealed elevated concentrations of P2O5, SO3, Cl and Zn in soil compared to sand and active transportation processes for sand but not soil. The comprehensive chemical makeup of the Martian soil (inactive bedforms) and sand (active bedforms) is characterized by its basaltic nature, with enriched volatile elements such as sulphur, chlorine and zinc, and the presence of minerals like plagioclase, pyroxene and olivine due to the cohesive nature of inactive bedforms. Physical weathering and wind flow velocity play a pivotal role in the formation of different sedimentary bodies, impacting grain size distribution and mineralogy. The effect of dust‐lifting on surface features is studied by analysing Perseverance‐MEDA observations at the Jezero crater to understand the short‐term changes in the bedform. These events are found to involve the redistribution of only a small amount of materials and, thereby, changing surface features on Mars over a short period. To detect the bedform migration in the Pasteur crater, several HiRISE images acquired over different time intervals were used. The changes in the ripple crest (~0.29–1.18 m/Earth year) and dune slip face suggest new grain flow events. In the Pasteur crater, extensive changes in sand deposits near the dunes signify a widespread bedform migration. The stronger north‐westerly and north‐easterly winds dominate these changes. Thus, the bedform migration in the three tropical craters exhibits significant variability driven by localized aeolian processes. This variability is crucial for understanding Mars' geological history, current surface dynamics and eventually, helps in planning future missions.

Risk Assessment of Heavy Metal Accumulation in Cucumber Fruits and Soil in a Greenhouse System with Long-Term Application of Organic Fertilizer and Chemical Fertilizer

Combining organic and chemical fertilizers is a sustainable strategy for vegetable production. However, there is limited research concerning the risks associated with heavy metals (HMs) in greenhouse systems with long-term location application. A three-year investigation, conducted from 2021 to 2023, explored a fifteen-year field experiment with combinations of chemical fertilizer (CH), corn straw (SW) and pig manure (PM). Five treatments were evaluated: excessive fertilization (high CH and PM), conventional fertilization (normal CH), organic–inorganic fertilization (3/4CN + 1/4PN, 2/4CN + 2/4PN and 2/4CN + 1/4PN + 1/4SN). This study evaluated the risks associated with heavy metals (HMs) by analyzing and quantifying their concentrations in soil and cucumber fruits, as well as by calculating the bioconcentration factors (BCFs), the geo-accumulation index (Igeo), and both the non-carcinogenic and carcinogenic risks. The results indicated that excessive fertilization (CF) increased the concentrations of Cu and Zn in fruits, as well as the Igeo values of Cu, Zn, and Cd, and the non-carcinogenic Cu risk, while decreasing the BCFs of Cu and Zn. Organic–inorganic fertilization also elevated the Igeo values of Cu and Zn. Redundancy analyses confirmed a positive correlation between the soil concentrations of Cu and Zn and higher levels of available phosphorus contents (48.4%), alongside a lower pH (4.9%). The concentrations of Cu, Zn, and Cd in both soil and cucumber fruits increased linearly with the duration of application and amount of input. Although the combined application of CH with PM or SW did not significantly elevate the non-carcinogenic or carcinogenic risks associated with most heavy metals, the carcinogenic risks of Cd and As emerged as potential risk factors after 15 years of organic–inorganic fertilization. Utilizing a combination of CH with PM and SW as a fertilizer management strategy can effectively address both the control of heavy metal inputs in the facility and the safety and quality of cucumbers.

Machine learning-assisted risk evaluation of heavy metals in the Hainan gold mining region, China.

This study employed machine learning (ML) to thoroughly investigate the impact of informal mining activities on the distribution and pollution status of heavy metals in soils near private gold mines in Hainan Province, southern China, a region known for its ecological sensitivity and economic importance. By systematically collecting surface soil samples and samples at depths of 0.5-1m from 175 drilling sites, a comprehensive quantitative analysis was conducted on major heavy metal elements, including lead (Pb), copper (Cu), cadmium (Cd), nickel (Ni), mercury (Hg), chromium (Cr), arsenic (As), and zinc (Zn). Combined with evaluation methods such as the Pollution Load Index (PLI), Normalized Pollution Index (NIPI), and Ecological Risk Index (ERI), the study revealed a high level of soil pollution at informal mining sites. The findings indicated that the average concentrations of Pb, Cd, Hg, As, and Zn in surface soils significantly exceeded the background values for soils in China, with a pronounced positive correlation observed between these heavy metal elements in both surface and deep soil profiles (r > 0.5). Furthermore, leveraging the heavy metal content in surface soils and the constructed environmental indicators, the predictive accuracy for metal content in deep soils was found to range from R2 = 0.27 to 0.68, suggesting that informal mining activities have led to substantial variations in metal content across different soil profiles. Through the application of a random forest model for predictive analysis of the PLI, NIPI, and ERI, high prediction accuracy was achieved (R2 = 0.78, 0.86, and 0.60, respectively). The study demonstrates that informal mining activities not only elevate the risk of soil pollution but also alter the distribution patterns of heavy metals. Also, this study provides a crucial foundation for the scientific assessment of soil quality and potential environmental hazards, while also affirming the efficacy of ML techniques in forecasting soil quality parameters.

Interaction Effects of Phosphorus and Zinc Application on Their Availability and Growth of Rice (<em>Oryza sativa</em>) in an Alfisol of Sri Lanka

This study investigated the interactive effects of phosphorus (P) and zinc (Zn) application on P and Zn availability, and growth of rice (Oryza sativa) in an Alfisol. In a laboratory incubation experiment, soil samples were supersaturated with treatment solutions with all possible combinations of four P levels (0, 6, 12, and 24 mg kg-1 equivalent to 0, 10, 20, and 40 kg ha-1, respectively) and three Zn levels (0, 1.2, and 2.4 mg kg-1 equivalent to 0, 2, and 4 kg ha-1, respectively), and then allowed to air-dry. Available P and Zn contents in soil increased as the application rates were increased but P×Zn rate interaction effect was not significant. In a pot experiment, rice (var Bg 358) was grown for 10 weeks with all possible combinations of three P levels (0, 5.5, and 16.5 mg kg-1) and three Zn levels (0, 1, and 2 mg kg-1). Initial soil P was higher than the critical level (12 mg kg-1), but available Zn was below the critical level (1.5 mg kg-1). The main effect of P rate did not significantly affect the number of tillers and shoot dry matter content while Zn application decreased them. Root dry matter, and root and shoot P concentrations were significantly (P<0.05) influenced by P×Zn rate interaction effect. While, plant P uptake was significantly decreased due to P and Zn application, plant Zn uptake was not affected. Therefore, for a better growth of rice plant, the soils with high available P and low Zn contents should be carefully fertilized with P and Zn fertilizers.

Isolation, screening of zinc solubilizing microorganisms and its application in low zinc calcareous soil

Inoculating zinc solubilizing microorganisms (ZSMs) is considered as a promising strategy for increasing Zn phytoavailability in soils with low Zn availability. In present study, we screened six strains of ZSMs from rhizosphere of green manure crop, including three strains of fungi, Talaromyces purpureogenus, Talaromyces pinophilus, and Penicillium amestolkiae, and three strains of bacteria, Cellulosimicrobium funkei, Isptericola cucumis and Streptomyces canus. We conducted a pot experiment of Bok choy inoculated with different ZSMs to analyze the Zn content in shoots and roots, and compared the Zn solubilizing effect of ZSMs. The results showed that Zn content in the roots and leaves of Bok choy of treatments inoculated with ZSMs were increased by 15%-44% and 27%-62%, respectively, and that soil DTPA-Zn concentration were increased by 52%-359%. The treatment inoculated with P. amestolkiae had the best effect. ZSMs significantly enhanced root uptake of Zn and foliar Zn content through increa-sing DTPA-Zn by mobilizing soil Zn by transformation of moderately available Zn (Zn bounded with manganese oxide and Zn strongly bounded with organic matter) to available Zn (exchangeable fraction, Zn bounded with carbonate, and Zn bounded with loose organic matter). The screened Zn mobilizing fungi averagely enhanced soil Zn phytoavailability and leaf Zn content by 240% and 46%, showing superior mobilizing ability than screened bacteria. P. amestolkiae significantly increased Zn content of soil and plant, thus it could be a promising potential microorganism as biofotification agent.

Toxicity factors, ecological and health risk assessments of heavy metal in the urban soil: a case study of an agro-machinery area in a developing country.

The contribution of heavy metals in surface soils by the influences of agro-machinery factories is a significant growing concern. Heavy metals were analyzed by inductively coupled plasma mass spectrometry technique to assess human and ecological risks. The concentrations of Fe, Cd, Cr, Cu, As, Pb, Mn, Ni, and Zn in soil ranged from 18,274-22,652, 2.06-4.92, 24.8-41.9, 126.8-137.5, 9.20-25.2, 17.8-46.1, 114.4-183.1, 86.9-118.1, and 101.6-159.6mg/kg, respectively. The enrichment factor values of heavy metals were greater than 1.5, suggesting severe anthropogenic activities such as untreated waste discharging, burning of metallic wastes, wear, and tear, and dismantling of old batteries for heavy metals enrichment in studied soil. The contamination factor indicates considerable to very high contamination of heavy metals in soil. Moderate to high ecological risk was observed for analyzed metals which mainly originated from the maintenance and repairing of various engines in the workshop and welding and soldering of metallic substances. The target hazard quotient (THQ) was ranged from 6.99E-04 to 2.21E-01 for adults and 5.59E-03 to 1.82E + 00 for children, respectively; indicating children were more sensitive to heavy metals exposure from soil dust. The carcinogenic risk of As (1.72E-05) exceeded the USEPA acceptable limits indicating cancer risk to the residence. The current emphasized the significance of intensive heavy metals monitoring in surface soils around the agro-machinery areas due to their potential health risks associated with children.

Determination of heavy metals and trace element contents in Veronica grisebachii S. M. WALTERS

This study aimed to determine the concentrations of Al, Ba, Cr, Co, Cu, Fe, Mn, Ni, Pb, S, and Zn in soil and Veronica grisebachii S. M. WALTERS samples. The present study focused on the heavy metal and essential element contents of this plant. Experimental materials were taken from the south eastern of Aksaray province at coordinates 38°13'54.5"N 34°08'28.8"E at an altitude of 1276 m above sea level from Turkey. Plant (root, stem and leaf parts) and soil mineral element measurements were done using standard methods. Heavy metals and essential element were analyzed in the plant by using ICP-MS. Also XRF device was used for measurements in soil. The results showed that the concentrations of Cr, Cu, Fe Pb, S, and Zn in the soil were within the optimum values, while the concentrations of Al, Co, Mn, and Ni were above the optimum values. The levels of Al, Co, Mn, and Ni in the soil of the plant's natural habitat are above the reference values. This species has a high capacity to absorb and accumulate heavy metals such as Al, Co, Mn, and Ni from the soil.

Transport characteristics of heavy metals in the soil-atmosphere-wheat system in farming areas and development of multiple linear regression predictive model

Heavy metal accumulation in agricultural products has become a major concern. Previous studies have focused on the transport of heavy metals from the soil and their accumulation in crops. However, recent studies revealed that wheat leaves, ears, and awns can also transport and accumulate heavy metals. Wheat grains can be influenced by two sources of heavy metals: soil contamination and atmospheric deposition. To comprehend the transport characteristics of heavy metals in soil, atmospheric deposition, and wheat, 37 samples each for wheat rhizosphere soil, wheat roots, stems, leaves, and grains were collected. Fifteen samples of atmospheric dry deposition and atmospheric wet deposition were collected from Linshu County (northern area), China. Based on the test data, the characteristics of heavy metals and their distribution in the study area were analyzed. Migration patterns of heavy metals in crops from different sources were investigated using Pearson correlation and redundancy analysis. Finally, a predictive model for heavy metals in wheat grains was developed using multiple linear regression analysis. Significant disparities in the distribution of heavy metals existed among wheat roots, stems, leaves, and grains. The coefficient of variation of heavy metals in atmospheric deposition was relatively high, indicating discernible spatial patterns influenced by human activities. Notably, a positive correlation was observed between the concentration of heavy metals in wheat grains and atmospheric deposition of Hg, Cd, and Pb. Conversely, Zn and Ni levels in wheat grains were significantly negatively associated with soil Zn, Ni, pH, and OM content. The contribution of heavy metal elements from different sources varied in their impact on the grain's heavy metal content. Specifically, atmospheric deposition was the primary source of Hg and Pb in wheat grains, while Cd, Ni, Cu, and Zn were predominantly derived from soil. Using a multiple linear regression model, we could accurately predict Hg, Pb, Cd, Ni, Zn, and As concentrations in crop grains. This model can facilitate quantitative evaluation of ecological risk of heavy metals accumulation in crops in the study area.

Phytoremediation potential in soils contaminated with zinc

The accumulation of heavy metals in soils and waters represents a risk for both the environmental and human health. In this context, phytoremediation has become an efficient, accessible technological solution to extract or remove inactive metals and metal pollutants from contaminated soils. Our objective is to assess the behavior of different native plants of the Cerrado of Maranhão, ipê roxo (Tabebuia impetiginosa) and aroeira (Myracrodrun urundeuva), in the phytoremediation of soils contaminated with Zinc (Zn) (II) under controlled greenhouse conditions. Between the species investigated, Tabebuia impetiginosa presented a higher biomass production (aerial part/root) than Myracrodrun urundeuva for the period of 25 days. In turn, in the 45-day period, root biomass was higher for Tabebuia impetiginosa in doped soil, while lower biomass production was found in the aroeira control group. The highest Zn concentrations in the root appeared in the period of 25 days for doped soil for both species, with an absorption of 142.10 mg kg-1 for Tabebuia impetiginosa and 150.57 mg kg-1 for Myracrodrun urundeuva. In the aerial part, the aroeira species had higher Zn concentration in doped soil in the 45-day period, 398.97 mg kg-1. Regarding the TF and BF, the species presented higher efficiency in zinc phytoextraction. Both species were able to absorb and tolerate the metals in the soil induced to stress. Finally, we conclude that Tabebuia impetiginosa and Myracrodrun urundeuva can be applied in phytostabilization and phytoextraction processes, with hyperaccumulating potential for the ions of Zn.

Soil micronutrients (Zn and Fe) fractions and response of rice (Oryza Sativa) in different soil of Haryana under rice-wheat cropping system

The significance of zinc and iron in crop production, particularly in rice-wheat cropping systems, has been increasingly recognized. The present study aimed to determine the effect of different soil samples collected from the rice-wheat cropping system of Haryana with different soil texture on rice grain yield and micronutrient content using a greenhouse trial with four levels of Fe (0, 25, 50 mg kg−1 as soil and 0.5% foliar spray of FeSO4 at 45 DAS) and four levels of Zn (0, 5, 10 mg kg−1 as soil and 0.5% foliar spray of ZnSO4 at 35 DAS). This study discovered that rice grain yield showed a positive correlation with soil Zn and Fe concentrations in soil before sowing and a negative correlation with soil Fe and Zn concentrations in soil after crop harvesting. In most of the soils studied, foliar spray alone Fe @ 0.5% foliar (45 DAS) and Zn @ 0.5% foliar (35 DAS) improved Fe and Zn concentrations in rice significantly more than soil application of 25 mg Fe kg−1 and 5 mg Zn kg−1, respectively. The rice grain yield in clay soil was 14-42% higher than in sandy soil with different doses of Zn and Fe application. The order of preponderance of different Fe and Zn fractions were CA-Fe < OM-Fe < EX-Fe < FeMnOX-Fe < Res-Fe and Res-Zn > FeMnOX-Zn > OM-Zn > CA-Zn > Ex-Zn in the soils, respectively. Conclusively, concomitant consideration of grain yield and grain Zn and Fe concentrations of rice are the sustainable approach toward food targets achievement.

Tree stumps as passive samplers for trace metal dust deposition

Atmospheric dust is contaminated by trace metals in many parts of the world due to human industrial activities. This study evaluates tree stumps as passive samplers of dust deposition and bioindicators of trace metal dust contamination in a mine impacted environment. Tree stumps (n = 230) and adjacent soils from Cu–Zn mining areas in northeastern China were analysed in situ for their trace metal concentrations using portable X-ray fluorescence (pXRF). Arsenic and Zn concentrations in tree stumps and roadside soils of each location all decreased with distance from the road in a power-law relationship, indicating a common pollution source (resuspension and redeposition of road dust). Micro-XRF images of vertical tree stump slices indicate that As and Zn were concentrated on the cut (uppermost) surface of tree stumps. This indicates atmospheric deposition as a primary contributor to elevated As and Zn concentrations in tree stumps. Trace metals in soils may have other sources besides atmospheric deposition (e.g., migration from buried ore-bodies or rock weathering), which may confound distinguishing sources in polluted areas. Here, we show that the analysis of tree stumps are suitable indicators of atmospheric trace metal contamination. Compared to surface soils, tree stumps can better reflect road dust resuspension and redeposition because unlike soils, atmospheric deposition is the primary contributor to their trace metal concentrations.