Heavy Metal-contaminated Soils Research Articles

Evaluation the Toxicity of Heavy Metal Mixtures in Anecic Earthworms (Aporrectodea giardi).

Using earthworms as bioindicators of heavy metal contamination in soils is a relevant tool for environmental risk monitoring. This study examines the combined effects of four distinct concentrations mixtures (M1, M2, M3 and M4) containing Cd, Cr, Cu, Ni, Fe and Mn on Aporrectodea giardi earthworms after 12 and 24days (12D/24D) of exposure via the monitoring of certain biomarkers of stress including total protein content, glutathione (GSH), metallothionein (MT), catalase and lipoxygenase (LOX) activities. The results show a decrease in the total protein level for the M3 mixture after 24D, whereas it increases for all other treatments regardless of exposure time. Glutathione and metallothionine levels increased for M2 and M3 and decreased for M1 and M4 after 12D; they increased after 24D for all the mixtures. Regarding enzyme activities, catalase activity was decreased for all the treatments unless for M3 (P > 0.05). However, LOX increased for M1, M2 and M4 except for M3 after 12D, when inhibition of this biomarker was observed. LOX activity was inhibited for all the mixtures at the end of the treatment. All the mixtures generated oxidative stress in Aporrectodea giardi, which is minimized by increasing MT levels to remove the metal ions and triggering the antioxidant system, composed primarily of GSH and LOX to restore cellular homeostasis. These findings suggest that the species Aporrectodea giardi could be an excellent candidate for ecotoxicological risk assessment of soils contaminated by metal mixtures and it can be used in bioremediation for its fitness which allows it to tolerate high concentrations of metal mixtures.

Benefit evaluation of in-situ Cd immobilization with naturally occurring minerals using an analytical hierarchy process

Immobilization has a wide range of applications in heavy metal-contaminated soil remediation, and immobilization agents serve as the key to the successful application of this technology. In this study, we designed a comprehensive and efficient scoring system based on an analytic hierarchy process (AHP) to evaluate the feasibility and effectiveness of three immobilization agents (wollastonite, dolomite, and calcite) in remediating Cd-polluted soil. The scoring system comprised four criteria and 11 indicators, and the results showed that all three immobilization agents significantly reduced the accumulation of Cd in rice. The Cd reduction rates of early rice with a single application of wollastonite, dolomite, and calcite were 67.6%, 46.9%, and 83.8%, respectively. Single or combined application of dolomite and calcite decreased the available Cd concentration in early rice soil, and the application of calcite resulted in an excellent rating of both early and late rice, demonstrating its highest immobilization and stability performance. Therefore, the immobilization efficiency of the three materials in descending order followed calcite > dolomite + thioglycols > wollastonite. In summary, this comprehensive evaluation system offers new insight into assessing the efficiency of soil remediation, serving as a valuable reference for selecting immobilization agents and making decisions regarding remediation plans for heavy metal-contaminated soil.

Bio-inoculation with Serratia CP-13 enhances Cd detoxification via modulation of phytohormone, gas exchange attributes and nutrient acquisition in maize cultivars cultivated in Cd-stressed soil

Heavy metals contamination of soil is increasing rapidly due to prompt in urbanization and industrialization. Recently, cadmium (Cd) pollution has emerged as a severe menace to plant and human health, while the use of plant growth promoting rhizobacteria (PGPR) has appeared as an economical approach for bioremediation of Cd toxicity in crop plants. In this study, the effect of Serratia sp. CP-13 inoculation on two maize cultivars in pre-Cd (0, 5, 12, 18, 26, 30 µM) spiked soil was evaluated. The combined effect of soil Cd and CP-13 application was assessed through the analysis of seed germination, plant biomass, phytohormones, gas exchange attributes, antioxidant production, plant Cd, and nutrient uptake in two (Sahiwal-2002, MMRI-Yellow) maize cultivars. Our outcomes exposed that single treatment of Cd-spiked soil significantly downregulates seed germination, plant biomass, plant nutrients, photosynthetic pigments, indole acetic acid (IAA), total protein, proline, total soluble sugar (TSS), stomatal conductance, transpiration rate, net photosynthesis, and antioxidant production, together with upregulating malondialdehyde (MDA), relative membrane permeability (RMP), abscisic acid (ABA), and Cd uptake in maize cultivars. However, this response of the maize crop against Cd-spiked soil was found to be maximal in Sahiwal-2002 at 30 µM Cd. Furthermore, the inoculation of Cd-resistant CP-13 significantly upregulates the plant accumulation of biomass, seed germination, antioxidants, IAA, gas exchange attributes, photosynthetic pigments, plant physiology, and nutrient uptake and downregulates the MDA, RMP, ABA, and root/shoot Cd accretion in two cultivars of maize. Moreover, this CP-13 based upregulation of plant growth was found to be cultivar (Sahiwal-2002) and Cd treatment (30 µM) specific by controlling the accumulation of lipid peroxidation, phytohormone content, and Cd detoxification. Further, our results indicate that the CP-13 might be a promising and cost effective future biofertilizer for bioremediation of soil Cd.

A new method for spatial three-dimensional prediction of soil heavy metals contamination

Soil heavy metals contamination are highly correlated to human health. It is crucial to employ three-dimensional heavy metals modeling and mapping for site assessment and remediation. However, current methods are limited due to the poor consideration of both spatial auto-correlation and stratified heterogeneity concurrently. The present study established a novel methodology 3D-MSN to model soil metals, encompassing autocorrelation and heterogeneity. In addition to considering in-strata correlation and between-strata heterogeneity like traditional methods, 3D-MSN accounted for the between-strata correlation to enhance the accuracy of prediction. A former agrochemical plant was used as a case to validate the superiority of the 3D-MSN method over traditional approaches. The accuracy of different methods was evaluated using mean absolute error (MAE) and root-mean-square error (RMSE), through leave-one-out cross-validation. Results demonstrated significant spatial autocorrelation and stratified heterogeneity for the presence of As and Cu in soil. 3D-MSN exhibited the lowest MAEs (2.424 mg/kg for As, 4.863 mg/kg for Cu) and RMSEs (3.439 mg/kg, 7.279 mg/kg) compared to 3D-ordinary kriging (MAEs (2.949 mg/kg, 6.482 mg/kg) and RMSEs (3.890 mg/kg, 8.364 mg/kg)) and 3D-stratified kriging (MAEs (2.571 mg/kg,5.184 mg/kg) and RMSEs (3.570 mg/kg, 7.412 mg/kg)). 3D-MSN also accounted for estimation uncertainties. Considering autocorrelation and stratified heterogeneity, 3D-MSN presented superior performance. This research contributes to advancing the field of three-dimensional heavy metal modeling and provides valuable insights for site assessment and remediation efforts.

Would it be better for partition prediction of heavy metal concentration in soils based on the fusion of XRF and Vis-NIR data?

Heavy metal (HM) contamination in soil necessitates effective methods to diagnose suspected contaminated areas and control rehabilitation processes. The synergistic use of proximal sensors demonstrates significant potential for rapid detection via accurate surveys of soil HM pollution at large scales and high sampling densities, and necessitates the selection of appropriate data mining and modeling methods for early diagnosis of soil pollution. The aim of this study is to evaluate the performance of a subarea model based on geographically partitioned and global models based on high-precision energy dispersive X-ray fluorescence (HD-XRF) and visible near-infrared (vis-NIR) spectra using a random forest model for predicting soil Cu and Pb concentrations. A total of 166 soil samples are acquired from a contaminated plot in Baiyin, Gansu Province, China. The soil samples are subjected to HM analysis and proximal sensor scanning in a laboratory. Vis-NIR spectral data are preprocessed using the Savitzky Golay (SG) and first-order derivative with Savitzky Golay (SGFD) methods. The results show that for predicting Cu and Pb concentrations in soil, the subarea models performs better than the global models in terms of quantitative prediction, based solely on individual HD-XRF data. For the subarea and global models, the R2 values are 0.961 and 0.981, respectively; the RMSE values are 27.8 and 79.6, respectively; and the RPD values are 4.96 and 7.38, respectively. However, making use of the random forest algorithm trained with data fusion obtained from the HD-XRF and vis-NIR sensors, the global model achieves the best predictions for Cu and Pb concentrations via HD-XRF + vis-NIR (SGFD) and HD-XRF + vis-NIR (SG), respectively. The results will provide a new perspective for modeling approaches to rapidly invert HM concentrations based on proximal sensor data fusion within a large scope of the study area.

Ecological Risk Evaluation of Heavy Metals in Soils near a Water Dam in Baljurashi, KSA, and Their Accumulation in Dodonaea viscosa

Soil’s contamination with heavy metals is a serious issue, and assessing their levels, regulating their sources, and finding cost-effective technology to limit their toxic effect and soil cleanup are of high priority. The focus of this study was to find out the extent of priority hazard heavy metal contamination in soils close to the Al-Janabeen water reservoir dam in Baljurashi, KSA, and the extent of their accumulation in the Dodonaea viscosa Tacq plant. Soil and plant samples were analyzed for heavy metal concentration using inductively coupled plasma spectroscopy (ICPS). Quantitative single and integrated contamination indices were used to characterize and evaluate the degree of heavy metal contamination in soils. The biological concentration factor (BCF) and the translocation factor (TF) were utilized to determine the extent of transfer and accumulation of heavy metals in the D. viscosa plant. Soil analysis showed the presence of Mn, Cu, Zn, Co, Cr, and Pb among the prioritized heavy metals with Cu, Zn, and Pb values being higher than those in natural background levels. The mean concentration order was Fe > Mn > Zn > Cu > Pb > Cr > Ni > Cr > Co. The single contamination indices’ quantification indicated marked contamination due to Mn, Zn, Cu, Co, Cr, and Pb elements. While integrated contamination factors’ computation showed low ecological risk due to accumulative metals of concern, Nemerow’s index (NI) showed that Cu, Zn, and Pb were the three most abundant pollutants in the examined soils. Analysis of plant parts showed the presence of Mn, Cu, Ni, Zn, Co, Cr, Cd, and Pb at varying quantities in various plant sections. Both BCF and TF factors were less than one, indicating that the D. viscosa plant was limited in its ability to phytoextract and accumulate the metals from the soil. This study suggests more research to locate suitable native plants for phytoremediation and soil cleaning is required in addition to the appropriate planning and management of landfills in order to ensure agricultural sustainability.

Study Progress on the Ecological Effects of Biochar in Soil

Soil is an indispensable and important part of human production and life, and biochar, as an important form of utilization of biomass energy, can be widely used in soil conditioning and crop conditioning. Currently, a systematic framework for studying biochar's ecological impact on soil is still required. This paper briefly introduces the basic preparation method of biochar, structural characterization of biochar, and briefly describes its basic properties. By adsorbing pollutants with a high specific surface area and strong adsorption, biochar can be used to clean up heavy metal contamination in soil. It can also boost soil fertility by increasing enzyme activity and organic carbon content, as well as by reducing bulk weight and increasing cation exchange to increase soil fertility retention capacity. In addition the moderate addition of biochar can also play a positive role in crop conditioning to a certain extent. The purpose of this paper is to summarize the basic theories and research related to the study of the ecological effects of biochar in soil by introducing the typical preparation methods and basic properties of biochar, so as to facilitate the subsequent further research.

Potential of Purslane (Portulaca oleracea L.) in Phytoremediation: A Study on the Bioaccumulation and Bio-Transfer of Cadmium, Nickel, and Copper in Contaminated Soils

As industrial and agricultural activities intensify and technology rapidly advances, soil pollution has escalated to alarming levels. The increasing contamination of agricultural areas and the crops cultivated therein has emerged as a significant contemporary issue. Phytoremediation, the use of plants to remove pollutants, is a promising method for mitigating soil heavy metal contamination. 
 This study investigates the bioaccumulation capacity of purslane (Portulaca oleracea L.), a potential phytoremediator, in soils artificially contaminated with cadmium (Cd), nickel (Ni), and copper (Cu). Purslane was cultivated under controlled conditions with varying doses of Cd, Ni, and Cu. After 55 days, the plants were harvested and analysed for heavy metal concentrations in their roots, stems, and leaves. Results demonstrated a direct correlation between environmental heavy metal concentration and plant heavy metal content, with the most significant accumulation occurring in the roots. Leaf chlorophyll content was adversely affected by increased Cd, Ni, and Cu applications. The highest Cu, Ni, and Cd contents were found in the roots at 140 mg kg-1 Cu, 80 mg kg-1 Ni, and 20 mg kg-1 Cd applications, respectively. The bio-transfer coefficient (BTC), a measure of heavy metal transport from the root region to the leaves, was calculated. The BTC values ranged from 0.84-1.09 for Cu, 0.39-0.84 for Ni, and >1 for Cd at the Control and 5 mg Cd kg-1 treatments. 
 These findings suggest that purslane has potential for phytoremediation of heavy metal-contaminated soils, although the bioaccumulation and bio-transfer of heavy metals are dependent on the specific metal and its concentration in the soil. The study also highlights the potential risks associated with the consumption of plants grown in heavy metal-contaminated soils, as heavy metals can accumulate in different plant tissues, potentially entering the food chain.

Assessing and Predicting Soil Quality in Heavy Metal-Contaminated Soils: Statistical and ANN-Based Techniques

Assessing and Predicting Soil Quality in Heavy Metal-Contaminated Soils: Statistical and ANN-Based Techniques

Codisposal of landfill leachate concentrate and antimony mine soils using a one-part geopolymer system for cationic and anionic heavy metals immobilization

Geopolymer solidification/stabilization technology has developed rapidly in the remediation field of heavy metal-contaminated soil. However, geopolymers exhibit low anionic heavy metal immobilization efficiency due to their electronegativity and alkali activation characteristics. This study constructed a one-part blast furnace slag-based geopolymer system using landfill leachate concentrate (LLC) as chlorine and humic acid sources and achieved the solidification/stabilization of cations (Cd, Cu, Hg, and Pb) and anions (Sb and As) in the antimony mine soils (AMS). The LLC addition increased the Sb and As fixation rates from 92%∼94% and 82∼86%, respectively, to over 99%, reducing the leaching concentration of all heavy metal ions to the ppb level. LLC improved the chemical stability and physical encapsulation of Sb/As in three ways: inducing a Friedel’s salt (FS) formation, enhancing humic acid complexation/chelation, and promoting geopolymerization. Wet curing was more conducive to FS formation in the geopolymer than dry curing and increased the 28-day compressive strength by 38.5%. Due to the SiO2 skeleton support effect in AMS, a 30 wt% AMS addition was beneficial for geopolymer strength development. Our study provided a harmless method for the codisposal of LLC and AMS and improved the efficiency of geopolymer fixation of complex heavy metal cations and anions.

Assessment of soil properties in technogenically disturbed lands of Kemerovo Oblast – Kuzbass

Recultivation is a critical operation after mining operations. In Kemerovo Oblast – Kuzbass, Russia, a lot of land has suffered degradation due to stripping operations. The purpose of the study is to examine the technical, technological, and biological properties of lands technogenically disturbed as part of coal mining operations in Kuzbass. The object under study is soil and soil cover in the Talda coal mine at the experimental site and adjacent territories. The research goal is achieved through the following methods. The granulometric composition of soil is assessed using the areometric method. The structural-aggregate analysis is performed based on the distribution of aggregate content by size with a set of soil sieves. Water stability is established using the method of disintegration of soil aggregates under a layer of water up to 2 cm high for 10 minutes. The ecological condition of the soil is assessed based on its enzyme and biological activity. The conducted investigation reveals increased stoniness, hygroscopicity, and low humus content of soils on technogenically disturbed land plots. Technogenically disturbed lands are marked by more acidic and heavy metal-contaminated soils. No exceedances are detected for pesticides and radionuclides. The results demonstrate weak enzymatic (cellulolytic, catalase, dehydrogenase, urease, phosphatase, invertase, and soil respiration) and catalytic activity of the soils. All obtained results of assessment of soil conditions on the experimental site and adjacent territories should be used in planning further experimental work on conducting the biological recultivation phase to minimize random experimental errors associated with the influence of native vegetation cover and primary soil conditions on the survival of crops sown on the site.

IntraPD model: Leaching of heavy metals from naturally contaminated soils

This paper presents a novel method for predicting the migration of heavy metal contaminants in soils that contain heavy metal pollutants deep within the particles, which may cause delayed leaching. The proposed approach, the intraparticle pore-diffusion (IntraPD) model, incorporates both intraparticle diffusion and sorption equilibrium and is utilized to simulate batch leaching tests of heavy metal-contaminated soils using the finite difference method. The IntraPD model can solve the leakage of heavy metals from contaminated soil particles of arbitrary particle size distribution as a one-dimensional, polar-symmetric problem in the spherical coordinate system, assuming the soil particles to be porous perfect spheres. The findings from the simulation demonstrate a notable impact of soil particle size distribution on both the leaching rate and the amount of contaminants. Specifically, the coefficient of uniformity, which indicates the ratio of the maximum to minimum particle size, was identified as a significant factor influencing the leaching rate. When the coefficient of uniformity is less than or equal to 5, it has a combined effect on the leaching rate. However, when the coefficient of uniformity exceeds 5, the maximum particle size becomes the primary determinant of the leaching rate. The proposed model provides a valuable tool for accurately simulating batch leaching tests of naturally contaminated soils with diverse particle size distributions.

Plant growth promoting rhizobacteria induced metal and salt stress tolerance in Brassica juncea through ion homeostasis

Soil heavy metal contamination and salinity constitute a major environmental problem worldwide. The affected area and impact of these problems are increasing day by day; therefore, it is imperative to restore their potential using environmentally friendly technology. Plant growth-promoting rhizobacteria (PGPR) provides a better option in this context. Thirty-seven bacteria were isolated from the rhizosphere of maize cultivated in metal- and salt-affected soils. Some selected bacterial strains grew well under a wide range of pH (4−10), salt (5–50 g/L), and Cd (50–1000 mg/L) stress. Three bacterial strains, Exiguobacterium aestuarii (UM1), Bacillus cereus (UM8), and Bacillus megaterium (UM35), were selected because of their robust growth and high tolerance to both stress conditions. The bacterial strains UM1, UM8, and UM35 showed P-solubilization, whereas UM8 and UM35 exhibited 1-aminocyclopropane-1-carboxylate deaminase activity and indole acetic acid (IAA) production, respectively. The bacterial strains were inoculated on Brassica juncea plants cultivated in Cd and salt-affected soils due to the above PGP activities and stress tolerance. Plants inoculated with the bacterial strains B. cereus and B. megaterium significantly (p < 0.05) increased shoot fresh weight (17 ± 1.17–29 ± 0.88 g/plant), shoot dry weight (2.50 ± 0.03–4.40 ± 0.32 g/plant), root fresh weight (7.30 ± 0.58–13.30 ± 0.58 g/plant), root dry weight (0.80 ± 0.04–2.00 ± 0.01 g/plant), and shoot K contents (62.76 ± 1.80–105.40 ± 1.15 mg/kg dwt) in normal and stressful conditions. The bacterial strain B. megaterium significantly (p < 0.05) decreased shoot Na+ and Cd++ uptake in single and dual stress conditions. Both bacterial strains, E. aestuarii and B. cereus, efficiently reduced Cd++ translocation and bioaccumulation in the shoot. Bacterial inoculation improved the uptake of K+ and Ca++, while restricted Na+ and Cd++ in B. juncea shoots indicated their potential to mitigate the dual stresses of salt and Cd in B. juncea through ion homeostasis.

Mechanical and microstructural evolution of solidified/stabilized heavy metal-contaminated soil under a hydro-chemical-mechanical coupling environment

The long-term effectiveness of Solidification/Stabilization (S/S) under realistic disposal scenarios is a common controversy of its application. This study sought to investigate the evolution of the mechanical properties and microstructure of Pb-Zn-Cd composite contaminated soil solidified/stabilized by cement and fly ash (CSCS) under a hydro-chemical-mechanical coupling environment (HCM). An HCM simulation system was developed to reproduce the simultaneous action of hydraulic, chemical, and stress environments on CSCS. The mechanical and microstructural evolution of CSCS under HCM was assessed using vertical settlement monitoring, unconfined compressive strength (UCS) test, computed tomography (CT), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The increasing environmental acidity induces an increase in vertical displacement and a decrease in UCS. The highest final settlement was 0.96 mm at pH 3 and a pressure of 250 kPa, which was 39.13 % greater than the value at pH 5 and 7. The UCS decreased by 18.54 % after 168 h of HCM treatment at pH 7, while the value reached 45.83 % when the pH was lowered to 3. Seepage contributes to initial hydration as evidenced by an increase in the early E50 of the CSCS. Hydrodynamic scouring and chemical erosion increase the pore size and deteriorate the soil structure, whereas compaction helps to redistribute soil particles, thus improving the structural integrity and uniformity of the CSCS.

Study on the effects of new developed biochar and sludge composite materials on copper and lead contaminated soil and its remediation mechanism

In this study, composite repair material was obtained by composting and fermentation of straw biochar and sludge according to the mass ratio of 1:4. The remediation effect of its composite remediation materials on heavy metals copper (Cu) and lead (Pb) in soil was investigated. The characterization results of the composite remediation material showed that the material had rich pore structure, high specific surface area and rich functional groups such as hydroxyl, carbonyl and carboxyl groups, and had high adsorption capacity for heavy metals in contaminated soil. The passivation effect of Cu and Pb in contaminated soil was investigated under different application amount (3%, 5%) and passivation time (15d, 60d). The changes of Cu and Pb content, availability and morphology distribution in the soil before and after the addition of remediation materials were analyzed. The results showed that the passivation effect of Cu and Pb in soil was significantly enhanced with increasing passivation time and application amount. In conclusion, the addition of remediation materials effectively reduced the content and effectiveness of heavy metals in the soil and promoted the change of Cu and Pb morphology in the heavy metal-contaminated soil, thus realizing the remediation of the heavy metal-contaminated soil.

Heavy Metal Contamination in Soil around a Gold Mining Site: A Case Study of Alaagba Community, Ile-Ife, Nigeria

Heavy Metal Contamination in Soil around a Gold Mining Site: A Case Study of Alaagba Community, Ile-Ife, Nigeria

Epoxy resin for solidification/stabilization of soil contaminated with copper (II): Leaching, mechanical, and microstructural characterization

Among different types of heavy metal-contaminated soil, copper (Cu)-contaminated soil is very serious, and the Cu concentration in it is usually very high. It is common to solidify/stabilize Cu-contaminated soil using alkaline cementitious material. However, the remediated Cu-contaminated soil fails to meet the requirements of environmental safety and load-bearing capacity. This dilemma in the remediation of Cu-contaminated soil hinders the effective utilization of land resources. In this study, epoxy resin (EP) was utilized to solidify/stabilize Cu-contaminated soil due to its stable and rapid curing performance and excellent resistance to acid, alkali, and salt erosion. The mechanical properties, environmental effects, and curing mechanism of EP-cured Cu-contaminated soil were investigated. The results showed that the application of EP significantly enhanced the unconfined compressive strength (UCS), cohesion and internal friction angle of Cu-contaminated soil. All specimens met the UCS criterion specified by the United States Environmental Protection Agency (USPEA), namely no less than 0.35 MPa, which indicated that those EP-cured Cu-contaminated soil were qualified for practical engineering applications. According to the toxicity characteristic leaching procedure (TCLP), the application of EP enhanced the stability of Cu in Cu-contaminated soil. The leaching index of Cu ranged from 11 to 14. A high leaching index showed that the S/S treatment was safe and effective and the remediated Cu-contaminated soil satisfied the environmental requirement for heavy metals. This study confirmed the feasibility of utilizing EP in the solidification/stabilization (S/S) technology to convert high-concentration Cu-contaminated soil into secure and stable engineering materials. The remediation of Cu-contaminated soil by EP lays a solid foundation for the safe treatment and reuse of heavy metal-contaminated land resources.

Toxicity of sulfhydryl attapulgite to Eisenia fetida

ABSTRACT Sulfhydryl attapulgite is an effective material for soil remediation, but its potential toxicity to animals in soil is not fully understood. Using Eisenia fetida as the test organism, the avoidance experiments, acute toxicity and cumulative toxicity experiments were carried out. The avoidance rate of Eisenia fetida on ATP-SH is 0–60%. Eisenia fetida not only avoid, but also tend to the soil-added ATP-SH to a certain degree. In the acute toxicity test, with the increase of ATP-SH addition, the total protein (T-Protein) content gradually decreases, and the maximum rate of decline is 51.18%. The catalase (CAT) and superoxide dismutase (T-SOD) activities gradually increase, and the maximum increase rates are 73.56% and 51.73%, respectively. The malondialdehyde (MDA) activity significantly increase 1.8 times. In the cumulative toxicity experiment, with the increase of ATP-SH addition, the maximum increase rate of T-Protein content is 31.52%. The CAT and T-SOD activities decrease 64.38% and 43.60% at most, respectively, and MDA activity increase 0.9 times. Following exposure to the soil-added ATP-SH for 30 days, Eisenia fetida adapt to the environment through its own regulatory mechanism. ATP-SH has good application security in remediation of heavy metal-contaminated soil.

Inversion of heavy metal copper content in soil-wheat systems using hyperspectral techniques and enrichment characteristics

The growing problem of heavy metal contamination in soil will seriously threaten the China's grain safety. The development of hyperspectral remote sensing technology provides the possibility to achieve rapid and non-destructive monitoring of soil heavy metal content. In this study, we used hyperspectral techniques and enrichment characteristics to explore the potential of wheat leaf spectral inversion for heavy metal copper (Cu) content in the soil-wheat system. First, we conducted potting experiments to plant wheat on soil contaminated with varying concentrations of the heavy metal Cu. Then, we analyzed the migration characteristics, correlation characteristics and enrichment characteristics of Cu in the soil-wheat system under different soil heavy metal Cu concentration treatments. Next, we analyzed the spectral and correlation features of wheat leaves, and explored the potential of wheat leaf spectra for the inversion of Cu content in full-band and eigen-band modeling. Finally, using the estimated Cu content of wheat leaves from the best inversion model, we further conducted inversions to obtain the Cu content and precision of the grain, stem, root, total soil, and soil-available states based on the enrichment characteristics. The results showed that: (1) The accumulation pattern was root > grain > leaf > stem when the soil Cu concentration was <200 mg kg−1, and root > leaf > stem > grain when the soil Cu concentration was >200 mg kg−1. (2) The correlation coefficients between the different analyzed elements of the soil-wheat system were high, and all of them reached a highly significant level (P < 0.01). This supports the use of wheat leaves to estimate the Cu contents of soil and different parts of wheat. (3) The best inversion accuracies were obtained by modeling second derivative (SD) spectra that were pre-processed by screening the characteristic bands. The modeled R2cv, RMSEcv,R2ev and RMSEev were 0.94, 2.72 mg kg−1, 0.91 and 3.64 mg kg−1, respectively. This indicates an excellent ability to estimate Cu content in wheat leaves. (4) Using the hyperspectral estimation of Cu content in wheat leaves and the grouped inversion of enrichment characteristics, the inversion accuracy was lower only for grains, and the R2cv and R2ev for stems and roots exceeded 0.90, those for total soil exceeded 0.85, and those for the soil available state exceeded 0.70. Therefore, it is possible to use the spectra of wheat leaves in combination with the inversion of enrichment characteristics to estimate the soil-wheat Cu content. This study provides guarantee and support for the detection of grain safety.

Isolation and Characterization of Plant Growth-Promoting Bacteria for the Phytoremediation of Diesel- and Heavy Metal-Contaminated Soil

Isolation and Characterization of Plant Growth-Promoting Bacteria for the Phytoremediation of Diesel- and Heavy Metal-Contaminated Soil