This study focuses on empirical modeling of the strength characteristics of urban soils contaminated with heavy metals using machine learning tools and their subsequent stabilization with ordinary Portland cement(OPC)...This study focuses on empirical modeling of the strength characteristics of urban soils contaminated with heavy metals using machine learning tools and their subsequent stabilization with ordinary Portland cement(OPC).For dataset collection,an extensive experimental program was designed to estimate the unconfined compressive strength(Qu)of heavy metal-contaminated soils collected from awide range of land use pattern,i.e.residential,industrial and roadside soils.Accordingly,a robust comparison of predictive performances of four data-driven models including extreme learning machines(ELMs),gene expression programming(GEP),random forests(RFs),and multiple linear regression(MLR)has been presented.For completeness,a comprehensive experimental database has been established and partitioned into 80%for training and 20%for testing the developed models.Inputs included varying levels of heavy metals like Cd,Cu,Cr,Pb and Zn,along with OPC.The results revealed that the GEP model outperformed its counterparts:explaining approximately 96%of the variability in both training(R2=0.964)and testing phases(R^(2)=0.961),and thus achieving the lowest RMSE and MAE values.ELM performed commendably but was slightly less accurate than GEP whereas MLR had the lowest performance metrics.GEP also provided the benefit of traceable mathematical equation,enhancing its applicability not just as a predictive but also as an explanatory tool.Despite its insights,the study is limited by its focus on a specific set of heavy metals and urban soil samples of a particular region,which may affect the generalizability of the findings to different contamination profiles or environmental conditions.The study recommends GEP for predicting Qu in heavy metal-contaminated soils,and suggests further research to adapt these models to different environmental conditions.展开更多
There have been reports of potential health risks for people from hydrophobic organic pollutants,such as polycyclic aromatic hydrocarbons(PAHs),polychlorinated hydrocarbons(PCHs),and organophosphate flame retardants(O...There have been reports of potential health risks for people from hydrophobic organic pollutants,such as polycyclic aromatic hydrocarbons(PAHs),polychlorinated hydrocarbons(PCHs),and organophosphate flame retardants(OPFRs).When a contaminated site is used for residential housing or public utility and recreation areas,the soil-bound organic pollutantsmight pose a threat to human health.In this study,we investigated the contamination profiles and potential risks to human health of 15 PAHs,6 PCHs,and 12 OPFRs in soils from four contaminated sites in China.We used an in vitro method to determine the oral bioaccessibility of soil pollutants.Total PAHswere found at concentrations ranging from26.4 ng/g to 987 ng/g.PCHs(0.27-14.3 ng/g)and OPFRs(6.30-310 ng/g)were detected,but at low levels compared to earlier reports.The levels of PAHs,PCHs,and OPFRs released from contaminated soils into simulated gastrointestinal fluids ranged from 1.74%to 91.0%,2.51%to 39.6%,and 1.37%to 96.9%,respectively.Based on both spiked and unspiked samples,we found that the oral bioaccessibility of pollutantswas correlated with their logKow andmolecularweight,and the total organic carbon content and pH of soils.PAHs in 13 out of 38 contaminated soil samples posed potential high risks to children.When considering oral bioaccessibility,nine soils still posed potential risks,while the risks in the remaining soils became negligible.The contribution of this paper is that it corrects the health risk of soil-bound organic pollutants by detecting bioaccessibility in actual soils from different contaminated sites.展开更多
The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined co...The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined compressive strength(UCS),California bearing ratio(CBR),and cyclic simple shear,are conducted.Cyclic simple shear experiments on LCCs were performed to evaluate the damping and shear modulus.The investigated factors are vertical load(VL),leachate content(LC),frequency(F),and shear strain(ShS)for LCC.Forensic-based investigation optimization(FBIO)and equilibrium optimizer algorithm(EOA)were utilized in addition to multiple types of ensemble models,including adaptive boosting(ADB),gradient boosting regression tree(GBRT),extreme gradient boosting(XGB) and random forest(RF).The comparison of the methods showed that GBRT-FBIO and XGB-EOA models outperformed other models for shear modulus and damping of LCC.The p-value less than 0.0001 shows the significance of the used models in the response surface methodology(RSM)method.展开更多
In recent years,there has been an intensifying focus within the soil contamination prevention and remediation sector,both domestically and internationally,on the off-site disposal of contaminated soils.The United Stat...In recent years,there has been an intensifying focus within the soil contamination prevention and remediation sector,both domestically and internationally,on the off-site disposal of contaminated soils.The United States and Japan,as pioneers in this field,have formulated and implemented a suite of policy standards and practical measures for the regional collaborative management of off-site soil disposal.This paper meticulously reviews and evaluates the existing research on the regional collaborative management of off-site soil disposal,analyzing the experiences and strategies of the United States and Japan from the perspectives of regulatory systems and practical implementation.In light of China’s specific circumstances,it proposes a series of strategic recommendations for the adaptation of these international experiences to the Chinese context.These include enhancement of Chinese legal standards for the regional collaborative management of contaminated land soil off-site disposal,improvement of risk control standards for soil pollution and specific regulations for off-site disposal,as well as delineation of objective criteria to define the scope of collaborative management.展开更多
Microbe-assisted phytoremediation is of great significance for the remediation of soil contaminated with heavy metals(HMs),and probiotics are beneficial microorganisms that can improve soil structure and fertility and...Microbe-assisted phytoremediation is of great significance for the remediation of soil contaminated with heavy metals(HMs),and probiotics are beneficial microorganisms that can improve soil structure and fertility and promote plant growth.However,there are few studies on probiotics applied to remediate soil contaminated with HMs,and whether probiotics can improve the efficiency of phytoremediation still needs to be further investigated.This study aimed to investigate the effects of two kinds of probiotics,Lactobacillus casei(Lc)and Bacillus licheniformis(Bl),on activating the remediation potential of leaf mustard,Brassica juncea(L.)Czerniak.,for soil contaminated with Cd and Zn using incubation and pot experiments.The results showed that the addition of the two probiotics significantly reduced soil pH by 0.05–0.32 units and improved the available contents of soil HMs(by 15.3%–60.0%and 7.1%–23.8%for Cd and Zn,respectively)in the incubation experiment.After probiotic addition,available Cd and Zn contents in soil treated with 1×10^(9) colony forming units(cfu)mL^(-1) Bl were 1.65-and 1.66-folds of those in the control without probiotic,respectively,in the pot experiment.Meanwhile,soil alkaline phosphatase,urease,and sucrose activities were increased,indicating that soil microbial metabolic activities were also stimulated.Addition of Lc and Bl significantly improved the biomass and chlorophyll contents of leaf mustard.The contents of Cd and Zn in shoots and roots were significantly increased in the treatment with 1×10^(5) cfu mL^(-1) Lc.Furthermore,the activities of plant antioxidant enzymes,including superoxide dismutase,peroxidase,and catalase,were increased,and the content of plant malondialdehyde was reduced,indicating that the resistance of plants to HMs was enhanced.These results indicated that these two kinds of probiotics could enhance the availability of Cd and Zn directly in soil and promote the growth of leaf mustard,thereby increasing the efficiency of phytoremediation for HMs.The study provides a useful reference for probiotic-assisted phytoremediation of soil contaminated with HMs.展开更多
Efficient and innovative nano-catalytic oxidation technologies offer a breakthrough in removing emerging contaminants(ECs)from water,surpassing the limitations of traditional methods.Environmental functional materials...Efficient and innovative nano-catalytic oxidation technologies offer a breakthrough in removing emerging contaminants(ECs)from water,surpassing the limitations of traditional methods.Environmental functional materials(EFMs),particularly high-end oxidation systems using eco-friendly nanomaterials,show promise for absorbing and degrading ECs.This literature review presents a comprehensive analysis of diverse traditional restoration techniques-biological,physical,and chemical-assessing their respective applications and limitations in pesticide-contaminated water purification.Through meticulous comparison,we unequivocally advocate for the imperative integration of environmentally benign nanomaterials,notably titanium-based variants,in forthcoming methodologies.Our in-depth exploration scrutinizes the catalytic efficacy,underlying mechanisms,and adaptability of pioneering titanium-based nanomaterials across a spectrum of environmental contexts.Additionally,strategic recommendations are furnished to surmount challenges and propel the frontiers of implementing eco-friendly nanomaterials in practical water treatment scenarios.展开更多
Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have ...Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have been applied for the remediation of chromiumcontaminated soils,with varying degrees of success depending on soil type and contaminant form.However,the removal rate of total chromium(Cr)and hexavalent chromium(Cr(Ⅵ))often fluctuates based on the chemical composition of the leaching agents,as well as the soil’s physicochemical properties,such as pH and Cr speciation stability.Therefore,this study investigates the effectiveness of 20 composite leaching systems,including deionized water,lime water,calcium chloride,sodium carbonate,and sodium phosphate,through soil column leaching tests.The aim was to evaluate their impact on soil pH,total Cr,and Cr(Ⅵ)removal,and to examine the transformation of various Cr species during the leaching process.Results reveal that lime water and sodium phosphate were particularly effective in stabilizing Cr(Ⅵ)and neutralizing soil pH,while total Cr removal amount ranged from 197.4 mg/kg to 1671.6 mg/kg and Cr(Ⅵ)removal amount ranged from 113.2mg/kg to 316.8mg/kg.We also find that using 0.2 mol/L citric acid,0.1 mol/L hydrochloric acid,and 1.2 mL/g lime solution adjusted soil pH to 7.37,with average removal efficiencies of 34.6%.for total Cr and 72.7%for Cr(Ⅵ).Overall,our results suggest that the combined use of lime water and sodium phosphate is an effective strategy for remediating chromium-contaminated soil,particularly for stabilizing unleached Cr and adjusting soil pH.展开更多
Cadmium(Cd)contamination of soil is a global environmental issue.Traditional remediation techniques such as immobilization,leaching,and phytoextraction have numerous shortcomings,which has led to growing interest in t...Cadmium(Cd)contamination of soil is a global environmental issue.Traditional remediation techniques such as immobilization,leaching,and phytoextraction have numerous shortcomings,which has led to growing interest in the development of low-cost,high-efficiency,and environmentally friendly agents for removing Cd from soil.In this study,four magnetite(Fe_(3)O_(4))/polyaniline(PANI)nanocomposites,Fe_(3)O_(4)(1.0)/PANI,Fe_(3)O_(4)(1.5)/PANI,Fe_(3)O_(4)(2.0)/PANI,and Fe_(3)O_(4)(2.5)/PANI,were developed using 4 mL aniline monomer and 1.0,1.5,2.0,and 2.5 g Fe_(3)O_(4),respectively,and used as remediation agents with magnetic separation and regeneration capabilities.The Cd adsorption isotherms showed a better fit to the Langmuir model,with Fe_(3)O_(4)(1.5)/PANI exhibiting the highest Cd adsorption capacity of 47.62 mg g^(-1) at 25℃.Then,Fe_(3)O_(4)(1.5)/PANI was used to remediate four Cd-contaminated soils typical in China(black,brown,cinnamon,and red),all with a Cd content of 180 mg kg^(-1) after spiking.The results showed that the total Cd removal efficiency was satisfactory at 25.25%–38.91%and the exchangeable Cd removal efficiency was 36.03%on average.In addition,soil basic properties did not show significant changes after remediation.Regarding the regeneration performance,a higher total Cd removal efficiency(27.89%–44.96%)was achieved after the first regeneration cycle of Fe_(3)O_(4)(1.5)/PANI.After two regeneration cycles,Fe_(3)O_(4)(1.5)/PANI exhibited decreased total Cd removal efficiency compared to after the first regeneration,but its efficiency remained above 95%of or higher than those of virgin Fe_(3)O_(4)(1.5)/PANI.The synthetic process of Fe_(3)O_(4)/PANI was simple and cost-effective,and Fe_(3)O_(4)/PANI exhibited a high Cd removal efficiency with easy recovery and recyclability.Therefore,Fe_(3)O_(4)/PANI is a promising solution for the sustainable and efficient remediation of Cd-contaminated soils,especially for the reclamation of highly contaminated development land.展开更多
Abstract:In today’s economy,determining accessible and affordable techniques to remove Heavy Metals(HMs)from wastewater is crucial.Activated carbon is highly effective in adsorbing HMs due to its large surface area a...Abstract:In today’s economy,determining accessible and affordable techniques to remove Heavy Metals(HMs)from wastewater is crucial.Activated carbon is highly effective in adsorbing HMs due to its large surface area and porous structure.It works by attracting and binding HM ions to its surface.Okoubaka is known for its medicinal properties and some studies suggest it has detoxifying effects.However,its specific role in HM removal would likely involve binding mechanisms like other plant-based materials.This study examines the efficiency of activated charcoal,charred versus uncharred Okoubaka plant materials,eggshells and oxalic acid to remove HMs like copper,lead,and zinc from contaminated water.展开更多
Petroleum contamination is considered as a major risk to the health of humans and environment.Biochars as low-cost and eco-friendly carbon materials,have been widely used for the removal of petroleum hydrocarbon in th...Petroleum contamination is considered as a major risk to the health of humans and environment.Biochars as low-cost and eco-friendly carbon materials,have been widely used for the removal of petroleum hydrocarbon in the environment.The purpose of this paper is to review the performance,mechanisms,and potential environmental toxicity of biochar,modified biochar and its integration use with other materials in petroleum contaminated soil and water.Specifically,the use of biochar in oil-contaminated water and soil as well as the factors that could influence the removal ability of biochar were systematically evaluated.In addition,the modification and integrated use of biochar for improving the removal efficiency were summarized from the aspects of sorption,biodegradation,chemical degradation,and reusability.Moreover,the functional impacts and associated ecotoxicity of pristine and modified biochars in various environments were demonstrated.Finally,some shortcoming of current approaches,and future research needs were provided for the future direction and challenges of modified biochar research.Overall,this paper gain insight into biochar application in petroleum remediation from the perspectives of performance enhancement and environmental sustainability.展开更多
Microbial fuel cells(MFCs)have become more prevalent in groundwater remediation due to their capacity for power generation,removal of pollution,ease of assembly,and low secondary contamination.It is currently being ev...Microbial fuel cells(MFCs)have become more prevalent in groundwater remediation due to their capacity for power generation,removal of pollution,ease of assembly,and low secondary contamination.It is currently being evaluated for practical application in an effort to eliminate groundwater pollution.However,a considerable majority of research was conducted in laboratories.But the operational circumstances including anaerobic characteristics,pH,and temperature vary at different sites.In addition,the complexity of contaminants and the positioning of MFCs significantly affect remediation performance.Taking the aforementioned factors into consideration,this reviewsummarizes a bibliography on the application of MFCs for the remediation of groundwater contamination during the last ten decades and assesses the impact of environmental conditions on the treatment performance.The design of the reactor,including configuration,dimensions,electrodes,membranes,separators,and target contaminants are discussed.This review aims to provide practical guidance for the future application of MFCs in groundwater remediation.展开更多
Persulfate is considered a convenient and efficient remediation agent for organic contaminated soil.However,the potential risk of sulfur into the soil remediation by persulfate remains ignored.In this study,glass bott...Persulfate is considered a convenient and efficient remediation agent for organic contaminated soil.However,the potential risk of sulfur into the soil remediation by persulfate remains ignored.In this study,glass bottles with different persulfate dosages and groundwater tables were set up to simulate persulfate remediation of organic pollutants(aniline).The results found sulfate to be the main end-product(83.0%–99.5%)of persulfate remediation after10 days.Moreover,H_(2)S accounted for 93.4%–99.4%of sulfur reduction end-products,suggesting that H_(2)S was the final fate of sulfur.H_(2)S was released rapidly after one to three days at a maximum concentration of 33.0 ppm,which is sufficient to make a person uncomfortable.According to the fitted curve results,H_(2)S concentration decreased to a safe concentration(0.15 ppm)after 20–85 days.Meanwhile,the maximum concentration of methanethiol reached 0.6 ppm.These results indicated that secondary pollution from persulfate remediation could release harmful gases over a long time.Therefore,persulfate should be used more carefully as a remediation agent for soil contamination.展开更多
Petroleum products contamination is a world-wide problem that threatens polluting groundwater and surface water systems. However, the problem is not only large-scale in scope when viewed from a case-by-case basis. Man...Petroleum products contamination is a world-wide problem that threatens polluting groundwater and surface water systems. However, the problem is not only large-scale in scope when viewed from a case-by-case basis. Many fueling, construction, agricultural, and industrial activities result in the problem of managing smaller quantities of these soils from an ecological safety perspective. Landfilling has been the disposal method of choice in the US;however, this option is becoming economically prohibitive and it does not really offer a true degradation fate for the pollutants. This study focused on the proving of an innovative biocell design that afforded a high level of petroleum degradation within a simple and cost effective design. Additionally, the design offered a remediation solution for sites not easily accessed. Soil contaminated with both diesel fuel and gasoline collected from a former filling station was used in this on-site remediation case study. Rapid biodegradation of the petroleum products were observed at the initiation of the study with rates leveling off as the study progressed with the final total petroleum hydrocarbon concentration being 10 mg/kg at Day 90. Oxygen uptake rates were monitored and found to nicely track both microbial activity and pollutant removal dynamics. The biocell design met all expectations by being effective, yet simple to build and operate.展开更多
Heavy metal contaminated water sources pose serious health risks for humans,animals,and plants.Exposure to and ingestion of heavy metals have been associated to liver,kidney,and brain function.Objective:The aim of thi...Heavy metal contaminated water sources pose serious health risks for humans,animals,and plants.Exposure to and ingestion of heavy metals have been associated to liver,kidney,and brain function.Objective:The aim of this research is to comparatively examine the metal removal efficacy of three solid bidentate chemicals and four plant materials.Study Design&Methods:Standard solutions of zinc(II)and lead(II)ions with concentrations of 1,000 ppm were respectively treated with OA(Oxalic Acid),dibasic bidentate ligands(sodium hydrogen phosphate and sodium carbonate).Then,the solutions were placed on a shaker for 15 h,centrifuged,and the supernatant was analyzed using ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectrometry).Results:All the solid bidentate adsorbents were very effective in removing zinc and lead(>90%).However,more lead than zinc was removed across all adsorbents except for lemon where equal percent of zinc and lead(49%)were removed.OA and Na2HPO4 removed about equal amount of lead(>99%).The plant materials(SP(Spinach),bell pepper and GBP(Green Bell Pepper)),respectively and preferentially removed more lead(98.9%,98.3%,81.5%)than zinc(91.7%,46%,46%).Conclusion:Although plant materials have gained attraction for the remediation of heavy metal,however,some bidentate chemical ligands such as OA,sodium carbonate and sodium hydrogen phosphates are even more effective in removing these metals from contaminated water.Furthermore,heavier metals are preferentially removed than lighter metals.展开更多
Crude oil spills have inflicted extensive disruption upon the Niger Delta ecosystem, resulting in crop loss and severe environmental damage. Such spills exacerbate heavy metal concentration within soil due to the pres...Crude oil spills have inflicted extensive disruption upon the Niger Delta ecosystem, resulting in crop loss and severe environmental damage. Such spills exacerbate heavy metal concentration within soil due to the presence of metallic ions. The Okpare-Olomu community has borne the brunt of crude oil pollution from illicit bunkering, sabotage, and equipment malfunction. This study targets an evaluation of ecological hazards linked to heavy metals (HMs) in crude oil impacted agriculturally soils within Okpare-Olomu in Ughelli South LGA of Delta State. In this study, 24 topsoil samples were obtained from areas affected by crude oil pollution;the heavy metal content was evaluated through atomic absorption spectrometry. The concentration ranges for HMs (mg/kg) in soil were: 24.1 - 23,174 (Cu);0.54 - 37.1 (Cd);9.05 - 54 (Cr);12 - 174 (Ni);18.5 - 8611 (Pb);and 148 - 9078 (Zn) at a soil depth of 0 - 15 cm. Notably, metal concentrations were recorded to be above permissible World Health Organization limits. Predominantly, Zn and Pb recorded higher heavy metal concentration when compared to other heavy metals analysed, notably at sampling points PT7 through PT24. Zinc and Pb contamination exhibited highly significant contamination factors, and contamination severity was evidenced across all sample points, signifying a grave risk level. Pollution load indices indicated pervasive extreme pollution levels. Geoaccumulation indices signaled moderate to strong pollution, mainly by Pb and Zn. Ecological risk assessments revealed variable levels of heavy metal contamination, from low to very high, with potential ecological risk reflecting markedly elevated levels. This study underscores the imperative for soil remediation to rectify ecological imbalances in agriculturally affected soil constituents.展开更多
Global industrialization over the past centuries has resulted in widespread contamination of the environment with organic and inorganic wastes and their pattern of disposal.The study aimed at isolating fungi from spen...Global industrialization over the past centuries has resulted in widespread contamination of the environment with organic and inorganic wastes and their pattern of disposal.The study aimed at isolating fungi from spent diesel contaminated soil around Ministry of Works in Aba,Abia State for biodegradation potentials on the soil properties.About four(4)fungal species were isolated from the five(5)sites using cultural and biochemical characteristics.The isolate was screened,and optical density measured using spectrophotometer.A total of 5 soil samples from each location(0-15 cm and 15-30 cm)were collected and homogenized to have composite sample.Samples were taken to the laboratory for analysis of soil physiochemical parameters,fungi count and biodegradable potential of the fungi using standard methods.Data obtained revealed that,physical property of the soil such as sand(85.20%±0.01%),silk(6.4%±0.01%)were lower than the control location except clay(17.39%±0.01%).Chemical properties revealed highest concentration of element such as pH(4.76±0.01),total nitrogen(0.18%±0.011%),total organic carbon(3.41±0.01),sodium(0.21±0.01),potassium(0.24±0.001),magnesium(4.41±0.015),calcium(5.21±0.015),organic matter(6.18±0.011),and available phosphorus(30.99±0.01).All elements in the study site were higher than the control site with an exception to sodium(Na),which was lower.Fungi isolate identified were Aspergillus niger,Trichoderma virdae,Aspergillus flavus,and Pencillum corylophlum.The degradation potential of fungi identified shows that consortium degraded 29%of diesel oil from the soil followed by A.flavus,T.virdae,A.niger and the least was T.corylophlum.The study concludes that despite indiscriminate disposal of spent diesel oil,the nutrient content was still higher than control and consortium performed well in degradation.展开更多
Heavy metals have been viewed as hazardous environmental pollutants, and anthropogenic activities due to their high toxicity and persistent nature in the environment. Anthropogenic activities such as artisanal mining,...Heavy metals have been viewed as hazardous environmental pollutants, and anthropogenic activities due to their high toxicity and persistent nature in the environment. Anthropogenic activities such as artisanal mining, industrial activities, improper usage of fertilizers and pesticides, and indiscriminate open waste disposal bring about an increase in the presence of heavy metals in the environment. In the Keffi Metropolis, different elements lead to land contamination which debilitates soil quality, plant survival, human well-being, and the environment as a result of extensive dispersion or quantity of heavy metals in the soil and water. In recent years, biochar has emerged as a promising soil amendment for mitigating heavy metal pollution due to its unique physicochemical properties. This paper provides the effects of softwood pellet biochar on the retention of heavy metals in contaminated soils. A microcosm experiment was carried out to investigate the effects of biochar on the retention of heavy metals in contaminated soils. This research aimed to give an overview of the effects of softwood biochar at different temperatures (550˚C and 700˚C) on the retention of heavy metals and metalloids released from the soil during water inundation. The results show that the addition of organic matter (grass chippings) minimizes heavy metal mobilization. Also, biochar at high temperatures is more effective than those at low temperatures. The expected outcome of the research analysis includes providing insights into the role of biochar in retaining heavy metal contamination and further understanding the use of biochar as a sorbent for the management of contaminated soil.展开更多
The effects of five amendments such as acetic acid（AA）, citric acid （CA）, ethylenediamine tetraacetic acid （EDTA）, sepiolite and phosphogypsum on growth and metal uptake of giant reed （Arundo donax L.） grown o...The effects of five amendments such as acetic acid（AA）, citric acid （CA）, ethylenediamine tetraacetic acid （EDTA）, sepiolite and phosphogypsum on growth and metal uptake of giant reed （Arundo donax L.） grown on soil contaminated by arsenic （As）, cadmium （Cd） and lead （Pb） were studied. The results showed that the shoot biomass of giant reed was enhanced by 24.8% and 15.0%, while superoxide mutase and catalase activities slightly varied when adding 5.0 mmol/kg CA and 2.5 mol/kg EDTA to soil as compared to the control, respectively. The concentrations of As, Cd and Pb in shoots were remarkably increased by the addition of 2.5 mmol/kg AA and CA, 5.0 mmol/kg EDTA, and 4.0 g/kg sepiolite as compared to the control. The accumulations of As and Cd were also significantly enhanced in the above condition, while the shoot Pb accumulation was noticeably enhanced by amending with 4.0 g/kg sepiolite and 8.0 g/kg phosphogysum, respectively. The results suggested that AA, CA and sepiolite could be used as optimum soil amendments for giant reed remediation system.展开更多
[Objective] The aim was to study on in-situ elimination effect on heavy metals in soil of the mining area by ramie （Boehmeria nivea （L.） Gaud.）. [Methods] Based on Xiangzhu No.3 and Zhongzhu No.1, we conducted res...[Objective] The aim was to study on in-situ elimination effect on heavy metals in soil of the mining area by ramie （Boehmeria nivea （L.） Gaud.）. [Methods] Based on Xiangzhu No.3 and Zhongzhu No.1, we conducted research on heavy metals contents of plants growing in soil of Qibao Mountain orefield in Liuyang, Hunan Province, and on characteristics of enrichment and transfer of heavy metals （Cu, Pb, Cd, Zn） under influence of the two ramie species. [Result] It was concluded that trend of Cu content in different parts of ramie was as follows： rootskinleafbone; trend of Pb was rootleafskinbone; trend of Cd was rootskinboneleaf; the trend of Zn was rootskinboneleaf. In farmland A （with low content of heavy metal）, for per square meter of plough horizon, effect of Zhong 1 on heavy metals transferring volume and the period for restoration of the soil into national standard one （Category Ⅲ of Environmental Quality Standard for Soil） have been concluded. Specifically, for Cu, the corresponding values were 3 404.44 mg and 8.59 y, respectively; for Pb, the values were 3 638.5 mg and 13.52 y; for Cd, the values were 720.48 mg and 1.49 y; for Zn, the values were 37 324.8 mg and 0.67 y. [Conclusion] Soil contaminated by Cu, Pb, Cd, and Zn in orefield can be rapidly restored by growing ramie.展开更多
[Objective] To study the remediation efficiency of red mud on Pb, Zn and Cd in the heavy metal contaminated paddy soil of mine area, to clarify its remediation mechanism and fertilizer efficiency on heavy metal contam...[Objective] To study the remediation efficiency of red mud on Pb, Zn and Cd in the heavy metal contaminated paddy soil of mine area, to clarify its remediation mechanism and fertilizer efficiency on heavy metal contaminated soil. [Method] The soil incubation experiment was conducted to study the effect of red mud on the pH values and electrical conductivity （EC）, and the remediation efficiency of red mud on lead （Pb）, zinc （Zn） and cadmium （Cd） in heavy metal contaminated soil. [Result] Red mud addition reduced the content of exchangeable Pb, Zn and Cd in the soil significantly. Compared with the control, when incubated for 30, 60 and 90 d with the red mud dosage of 4% （W/W）, the exchangeable Pb content was decreased by 39.25%, 41.38% and 50.19%; exchangeable Zn content was decreased by 49.26%, 57.32% and 47.16%; and exchangeable Cd content was decreased by 19.53%, 24.06% and 25.70%, respectively. The application of red mud had significant impact on the share of Pb, Zn and Cd contents in five forms, and different amounts of red mud application all reduced the proportion of exchangeable Pb, Zn and Cd to the total Pb, Zn and Cd. In addition, the proportion of exchangeable Pb, Zn and Cd to total Pb, Zn and Cd decreased with the increasing amount of red mud addition. [Conclusion] The study provided references for reasonable application of red mud and reduction of heavy metal pollution in paddy soil.展开更多
基金funded by the Natural Science Foundation of China(Grant No.52090084)was partially supported by the Sand Hazards and Opportunities for Resilience,Energy,and Sustainability(SHORES)Center,funded by Tamkeen under the NYUAD Research Institute Award CG013.
文摘This study focuses on empirical modeling of the strength characteristics of urban soils contaminated with heavy metals using machine learning tools and their subsequent stabilization with ordinary Portland cement(OPC).For dataset collection,an extensive experimental program was designed to estimate the unconfined compressive strength(Qu)of heavy metal-contaminated soils collected from awide range of land use pattern,i.e.residential,industrial and roadside soils.Accordingly,a robust comparison of predictive performances of four data-driven models including extreme learning machines(ELMs),gene expression programming(GEP),random forests(RFs),and multiple linear regression(MLR)has been presented.For completeness,a comprehensive experimental database has been established and partitioned into 80%for training and 20%for testing the developed models.Inputs included varying levels of heavy metals like Cd,Cu,Cr,Pb and Zn,along with OPC.The results revealed that the GEP model outperformed its counterparts:explaining approximately 96%of the variability in both training(R2=0.964)and testing phases(R^(2)=0.961),and thus achieving the lowest RMSE and MAE values.ELM performed commendably but was slightly less accurate than GEP whereas MLR had the lowest performance metrics.GEP also provided the benefit of traceable mathematical equation,enhancing its applicability not just as a predictive but also as an explanatory tool.Despite its insights,the study is limited by its focus on a specific set of heavy metals and urban soil samples of a particular region,which may affect the generalizability of the findings to different contamination profiles or environmental conditions.The study recommends GEP for predicting Qu in heavy metal-contaminated soils,and suggests further research to adapt these models to different environmental conditions.
基金supported by the National Key Research and Development Program of China(No.2019YFC1804604)Basic and Applied Basic Research Foundation of Guangdong Province(No.2021A1515010018).
文摘There have been reports of potential health risks for people from hydrophobic organic pollutants,such as polycyclic aromatic hydrocarbons(PAHs),polychlorinated hydrocarbons(PCHs),and organophosphate flame retardants(OPFRs).When a contaminated site is used for residential housing or public utility and recreation areas,the soil-bound organic pollutantsmight pose a threat to human health.In this study,we investigated the contamination profiles and potential risks to human health of 15 PAHs,6 PCHs,and 12 OPFRs in soils from four contaminated sites in China.We used an in vitro method to determine the oral bioaccessibility of soil pollutants.Total PAHswere found at concentrations ranging from26.4 ng/g to 987 ng/g.PCHs(0.27-14.3 ng/g)and OPFRs(6.30-310 ng/g)were detected,but at low levels compared to earlier reports.The levels of PAHs,PCHs,and OPFRs released from contaminated soils into simulated gastrointestinal fluids ranged from 1.74%to 91.0%,2.51%to 39.6%,and 1.37%to 96.9%,respectively.Based on both spiked and unspiked samples,we found that the oral bioaccessibility of pollutantswas correlated with their logKow andmolecularweight,and the total organic carbon content and pH of soils.PAHs in 13 out of 38 contaminated soil samples posed potential high risks to children.When considering oral bioaccessibility,nine soils still posed potential risks,while the risks in the remaining soils became negligible.The contribution of this paper is that it corrects the health risk of soil-bound organic pollutants by detecting bioaccessibility in actual soils from different contaminated sites.
文摘The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined compressive strength(UCS),California bearing ratio(CBR),and cyclic simple shear,are conducted.Cyclic simple shear experiments on LCCs were performed to evaluate the damping and shear modulus.The investigated factors are vertical load(VL),leachate content(LC),frequency(F),and shear strain(ShS)for LCC.Forensic-based investigation optimization(FBIO)and equilibrium optimizer algorithm(EOA)were utilized in addition to multiple types of ensemble models,including adaptive boosting(ADB),gradient boosting regression tree(GBRT),extreme gradient boosting(XGB) and random forest(RF).The comparison of the methods showed that GBRT-FBIO and XGB-EOA models outperformed other models for shear modulus and damping of LCC.The p-value less than 0.0001 shows the significance of the used models in the response surface methodology(RSM)method.
基金supported by the National Social Science Foundation of China(Grant No.20&ZD091)the National Social Science Fund on the Spirit of the Sixth Plenary Session of the 19th Central Committee of the Communist Party of China(Grant No.22ZDA109)+1 种基金the 2024 Innovative Talents International Cooperation Training Program of the China Scholarship Council(Grant No.202406720002)the the 2024 Hunan Provincial Education Department Graduate Innovation Research Project(Grant No.CX20240485).
文摘In recent years,there has been an intensifying focus within the soil contamination prevention and remediation sector,both domestically and internationally,on the off-site disposal of contaminated soils.The United States and Japan,as pioneers in this field,have formulated and implemented a suite of policy standards and practical measures for the regional collaborative management of off-site soil disposal.This paper meticulously reviews and evaluates the existing research on the regional collaborative management of off-site soil disposal,analyzing the experiences and strategies of the United States and Japan from the perspectives of regulatory systems and practical implementation.In light of China’s specific circumstances,it proposes a series of strategic recommendations for the adaptation of these international experiences to the Chinese context.These include enhancement of Chinese legal standards for the regional collaborative management of contaminated land soil off-site disposal,improvement of risk control standards for soil pollution and specific regulations for off-site disposal,as well as delineation of objective criteria to define the scope of collaborative management.
基金supported by the Science and Technology Overall Innovation Project of Shaanxi Province,China(No.2016 KTCQ03-20)the Scientific Research Foundation Project of Quzhou University,China(No.KYQD006224002).
文摘Microbe-assisted phytoremediation is of great significance for the remediation of soil contaminated with heavy metals(HMs),and probiotics are beneficial microorganisms that can improve soil structure and fertility and promote plant growth.However,there are few studies on probiotics applied to remediate soil contaminated with HMs,and whether probiotics can improve the efficiency of phytoremediation still needs to be further investigated.This study aimed to investigate the effects of two kinds of probiotics,Lactobacillus casei(Lc)and Bacillus licheniformis(Bl),on activating the remediation potential of leaf mustard,Brassica juncea(L.)Czerniak.,for soil contaminated with Cd and Zn using incubation and pot experiments.The results showed that the addition of the two probiotics significantly reduced soil pH by 0.05–0.32 units and improved the available contents of soil HMs(by 15.3%–60.0%and 7.1%–23.8%for Cd and Zn,respectively)in the incubation experiment.After probiotic addition,available Cd and Zn contents in soil treated with 1×10^(9) colony forming units(cfu)mL^(-1) Bl were 1.65-and 1.66-folds of those in the control without probiotic,respectively,in the pot experiment.Meanwhile,soil alkaline phosphatase,urease,and sucrose activities were increased,indicating that soil microbial metabolic activities were also stimulated.Addition of Lc and Bl significantly improved the biomass and chlorophyll contents of leaf mustard.The contents of Cd and Zn in shoots and roots were significantly increased in the treatment with 1×10^(5) cfu mL^(-1) Lc.Furthermore,the activities of plant antioxidant enzymes,including superoxide dismutase,peroxidase,and catalase,were increased,and the content of plant malondialdehyde was reduced,indicating that the resistance of plants to HMs was enhanced.These results indicated that these two kinds of probiotics could enhance the availability of Cd and Zn directly in soil and promote the growth of leaf mustard,thereby increasing the efficiency of phytoremediation for HMs.The study provides a useful reference for probiotic-assisted phytoremediation of soil contaminated with HMs.
基金supported by the Research Platform Open Fund Project of Zhejiang Industry and Trade Vocation College(No.Kf202203)the Scientific Research Project of CCCC First Harbor Engineering Company Ltd.(No.2022-7-2)+3 种基金the National Natural Science Foundation of China(No.22406142)the Fellowship of China National Postdoctoral Program for Innovative Talents(No.BX20230262)the Fellowship of China Postdoctoral Science Foundation(No.2023M732636)the Shanghai Post-doctoral Excellence Program(No.2023755).
文摘Efficient and innovative nano-catalytic oxidation technologies offer a breakthrough in removing emerging contaminants(ECs)from water,surpassing the limitations of traditional methods.Environmental functional materials(EFMs),particularly high-end oxidation systems using eco-friendly nanomaterials,show promise for absorbing and degrading ECs.This literature review presents a comprehensive analysis of diverse traditional restoration techniques-biological,physical,and chemical-assessing their respective applications and limitations in pesticide-contaminated water purification.Through meticulous comparison,we unequivocally advocate for the imperative integration of environmentally benign nanomaterials,notably titanium-based variants,in forthcoming methodologies.Our in-depth exploration scrutinizes the catalytic efficacy,underlying mechanisms,and adaptability of pioneering titanium-based nanomaterials across a spectrum of environmental contexts.Additionally,strategic recommendations are furnished to surmount challenges and propel the frontiers of implementing eco-friendly nanomaterials in practical water treatment scenarios.
基金supported by the National Key Research and Development Program of China(No.2023YFC3707902)China Postdoctoral Science Foundation(No.2024M752168)+1 种基金Jiangsu Funding Programfor Excellent Postdoctoral Talent(No.2024ZB393)the National Natural Science Foundation of China(No.42407126).
文摘Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have been applied for the remediation of chromiumcontaminated soils,with varying degrees of success depending on soil type and contaminant form.However,the removal rate of total chromium(Cr)and hexavalent chromium(Cr(Ⅵ))often fluctuates based on the chemical composition of the leaching agents,as well as the soil’s physicochemical properties,such as pH and Cr speciation stability.Therefore,this study investigates the effectiveness of 20 composite leaching systems,including deionized water,lime water,calcium chloride,sodium carbonate,and sodium phosphate,through soil column leaching tests.The aim was to evaluate their impact on soil pH,total Cr,and Cr(Ⅵ)removal,and to examine the transformation of various Cr species during the leaching process.Results reveal that lime water and sodium phosphate were particularly effective in stabilizing Cr(Ⅵ)and neutralizing soil pH,while total Cr removal amount ranged from 197.4 mg/kg to 1671.6 mg/kg and Cr(Ⅵ)removal amount ranged from 113.2mg/kg to 316.8mg/kg.We also find that using 0.2 mol/L citric acid,0.1 mol/L hydrochloric acid,and 1.2 mL/g lime solution adjusted soil pH to 7.37,with average removal efficiencies of 34.6%.for total Cr and 72.7%for Cr(Ⅵ).Overall,our results suggest that the combined use of lime water and sodium phosphate is an effective strategy for remediating chromium-contaminated soil,particularly for stabilizing unleached Cr and adjusting soil pH.
基金financially supported by the National Natural Science Foundation of China(No.41807116)the Natural Science Foundation of Fujian Province,China(Nos.2023J01418,2019J05035,and 2022N0024)+2 种基金the Scientific and Technological Innovation Project of China Metallurgical Geology Bureau(No.CMGBKY202301)the Independent Innovation Foundation of Tianjin University and Fuzhou University,China(No.TF2023-3)the Fuzhou University Testing Fund of Precious Apparatus,China(No.2023T014).
文摘Cadmium(Cd)contamination of soil is a global environmental issue.Traditional remediation techniques such as immobilization,leaching,and phytoextraction have numerous shortcomings,which has led to growing interest in the development of low-cost,high-efficiency,and environmentally friendly agents for removing Cd from soil.In this study,four magnetite(Fe_(3)O_(4))/polyaniline(PANI)nanocomposites,Fe_(3)O_(4)(1.0)/PANI,Fe_(3)O_(4)(1.5)/PANI,Fe_(3)O_(4)(2.0)/PANI,and Fe_(3)O_(4)(2.5)/PANI,were developed using 4 mL aniline monomer and 1.0,1.5,2.0,and 2.5 g Fe_(3)O_(4),respectively,and used as remediation agents with magnetic separation and regeneration capabilities.The Cd adsorption isotherms showed a better fit to the Langmuir model,with Fe_(3)O_(4)(1.5)/PANI exhibiting the highest Cd adsorption capacity of 47.62 mg g^(-1) at 25℃.Then,Fe_(3)O_(4)(1.5)/PANI was used to remediate four Cd-contaminated soils typical in China(black,brown,cinnamon,and red),all with a Cd content of 180 mg kg^(-1) after spiking.The results showed that the total Cd removal efficiency was satisfactory at 25.25%–38.91%and the exchangeable Cd removal efficiency was 36.03%on average.In addition,soil basic properties did not show significant changes after remediation.Regarding the regeneration performance,a higher total Cd removal efficiency(27.89%–44.96%)was achieved after the first regeneration cycle of Fe_(3)O_(4)(1.5)/PANI.After two regeneration cycles,Fe_(3)O_(4)(1.5)/PANI exhibited decreased total Cd removal efficiency compared to after the first regeneration,but its efficiency remained above 95%of or higher than those of virgin Fe_(3)O_(4)(1.5)/PANI.The synthetic process of Fe_(3)O_(4)/PANI was simple and cost-effective,and Fe_(3)O_(4)/PANI exhibited a high Cd removal efficiency with easy recovery and recyclability.Therefore,Fe_(3)O_(4)/PANI is a promising solution for the sustainable and efficient remediation of Cd-contaminated soils,especially for the reclamation of highly contaminated development land.
基金The Sherman Fairchild Foundation Undergraduate Research GrantThe National Science Foundation Award#1912400:HBCU-UP Implementation Project:Improving Minority Participation and Completion through STEM at Dillard University(IMPACTS@DU Ⅱ)Dillard University Endowed Professorship,funds。
文摘Abstract:In today’s economy,determining accessible and affordable techniques to remove Heavy Metals(HMs)from wastewater is crucial.Activated carbon is highly effective in adsorbing HMs due to its large surface area and porous structure.It works by attracting and binding HM ions to its surface.Okoubaka is known for its medicinal properties and some studies suggest it has detoxifying effects.However,its specific role in HM removal would likely involve binding mechanisms like other plant-based materials.This study examines the efficiency of activated charcoal,charred versus uncharred Okoubaka plant materials,eggshells and oxalic acid to remove HMs like copper,lead,and zinc from contaminated water.
基金supported by the Yunnan Fundamental Research Projects(No.202201BE070001-043)the Yunnan Provincial Excellent Young Scientists Fund(No.202201AW070006)+1 种基金USDA-NRCS(No.NR217217XXXXG004)the USDA National Institute of Food and Agriculture Hatch Project(No.7003969)。
文摘Petroleum contamination is considered as a major risk to the health of humans and environment.Biochars as low-cost and eco-friendly carbon materials,have been widely used for the removal of petroleum hydrocarbon in the environment.The purpose of this paper is to review the performance,mechanisms,and potential environmental toxicity of biochar,modified biochar and its integration use with other materials in petroleum contaminated soil and water.Specifically,the use of biochar in oil-contaminated water and soil as well as the factors that could influence the removal ability of biochar were systematically evaluated.In addition,the modification and integrated use of biochar for improving the removal efficiency were summarized from the aspects of sorption,biodegradation,chemical degradation,and reusability.Moreover,the functional impacts and associated ecotoxicity of pristine and modified biochars in various environments were demonstrated.Finally,some shortcoming of current approaches,and future research needs were provided for the future direction and challenges of modified biochar research.Overall,this paper gain insight into biochar application in petroleum remediation from the perspectives of performance enhancement and environmental sustainability.
基金supported by the National Natural Science Foundation of China(Nos.U22A20591 and 42077185)the Sichuan Science and Technology Program(Nos.2022ZYD0040 and 2022JDJQ0010)+1 种基金the National Key Research and Development Program of China(No.2020YFC1808300)the Research Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(No.SKLGP2020Z002).
文摘Microbial fuel cells(MFCs)have become more prevalent in groundwater remediation due to their capacity for power generation,removal of pollution,ease of assembly,and low secondary contamination.It is currently being evaluated for practical application in an effort to eliminate groundwater pollution.However,a considerable majority of research was conducted in laboratories.But the operational circumstances including anaerobic characteristics,pH,and temperature vary at different sites.In addition,the complexity of contaminants and the positioning of MFCs significantly affect remediation performance.Taking the aforementioned factors into consideration,this reviewsummarizes a bibliography on the application of MFCs for the remediation of groundwater contamination during the last ten decades and assesses the impact of environmental conditions on the treatment performance.The design of the reactor,including configuration,dimensions,electrodes,membranes,separators,and target contaminants are discussed.This review aims to provide practical guidance for the future application of MFCs in groundwater remediation.
基金supported by the National Key R&D Program of China (No.2018YFC1800506)the Key R&D Program of Zhejiang Province (No.2020C03083)。
文摘Persulfate is considered a convenient and efficient remediation agent for organic contaminated soil.However,the potential risk of sulfur into the soil remediation by persulfate remains ignored.In this study,glass bottles with different persulfate dosages and groundwater tables were set up to simulate persulfate remediation of organic pollutants(aniline).The results found sulfate to be the main end-product(83.0%–99.5%)of persulfate remediation after10 days.Moreover,H_(2)S accounted for 93.4%–99.4%of sulfur reduction end-products,suggesting that H_(2)S was the final fate of sulfur.H_(2)S was released rapidly after one to three days at a maximum concentration of 33.0 ppm,which is sufficient to make a person uncomfortable.According to the fitted curve results,H_(2)S concentration decreased to a safe concentration(0.15 ppm)after 20–85 days.Meanwhile,the maximum concentration of methanethiol reached 0.6 ppm.These results indicated that secondary pollution from persulfate remediation could release harmful gases over a long time.Therefore,persulfate should be used more carefully as a remediation agent for soil contamination.
文摘Petroleum products contamination is a world-wide problem that threatens polluting groundwater and surface water systems. However, the problem is not only large-scale in scope when viewed from a case-by-case basis. Many fueling, construction, agricultural, and industrial activities result in the problem of managing smaller quantities of these soils from an ecological safety perspective. Landfilling has been the disposal method of choice in the US;however, this option is becoming economically prohibitive and it does not really offer a true degradation fate for the pollutants. This study focused on the proving of an innovative biocell design that afforded a high level of petroleum degradation within a simple and cost effective design. Additionally, the design offered a remediation solution for sites not easily accessed. Soil contaminated with both diesel fuel and gasoline collected from a former filling station was used in this on-site remediation case study. Rapid biodegradation of the petroleum products were observed at the initiation of the study with rates leveling off as the study progressed with the final total petroleum hydrocarbon concentration being 10 mg/kg at Day 90. Oxygen uptake rates were monitored and found to nicely track both microbial activity and pollutant removal dynamics. The biocell design met all expectations by being effective, yet simple to build and operate.
文摘Heavy metal contaminated water sources pose serious health risks for humans,animals,and plants.Exposure to and ingestion of heavy metals have been associated to liver,kidney,and brain function.Objective:The aim of this research is to comparatively examine the metal removal efficacy of three solid bidentate chemicals and four plant materials.Study Design&Methods:Standard solutions of zinc(II)and lead(II)ions with concentrations of 1,000 ppm were respectively treated with OA(Oxalic Acid),dibasic bidentate ligands(sodium hydrogen phosphate and sodium carbonate).Then,the solutions were placed on a shaker for 15 h,centrifuged,and the supernatant was analyzed using ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectrometry).Results:All the solid bidentate adsorbents were very effective in removing zinc and lead(>90%).However,more lead than zinc was removed across all adsorbents except for lemon where equal percent of zinc and lead(49%)were removed.OA and Na2HPO4 removed about equal amount of lead(>99%).The plant materials(SP(Spinach),bell pepper and GBP(Green Bell Pepper)),respectively and preferentially removed more lead(98.9%,98.3%,81.5%)than zinc(91.7%,46%,46%).Conclusion:Although plant materials have gained attraction for the remediation of heavy metal,however,some bidentate chemical ligands such as OA,sodium carbonate and sodium hydrogen phosphates are even more effective in removing these metals from contaminated water.Furthermore,heavier metals are preferentially removed than lighter metals.
文摘Crude oil spills have inflicted extensive disruption upon the Niger Delta ecosystem, resulting in crop loss and severe environmental damage. Such spills exacerbate heavy metal concentration within soil due to the presence of metallic ions. The Okpare-Olomu community has borne the brunt of crude oil pollution from illicit bunkering, sabotage, and equipment malfunction. This study targets an evaluation of ecological hazards linked to heavy metals (HMs) in crude oil impacted agriculturally soils within Okpare-Olomu in Ughelli South LGA of Delta State. In this study, 24 topsoil samples were obtained from areas affected by crude oil pollution;the heavy metal content was evaluated through atomic absorption spectrometry. The concentration ranges for HMs (mg/kg) in soil were: 24.1 - 23,174 (Cu);0.54 - 37.1 (Cd);9.05 - 54 (Cr);12 - 174 (Ni);18.5 - 8611 (Pb);and 148 - 9078 (Zn) at a soil depth of 0 - 15 cm. Notably, metal concentrations were recorded to be above permissible World Health Organization limits. Predominantly, Zn and Pb recorded higher heavy metal concentration when compared to other heavy metals analysed, notably at sampling points PT7 through PT24. Zinc and Pb contamination exhibited highly significant contamination factors, and contamination severity was evidenced across all sample points, signifying a grave risk level. Pollution load indices indicated pervasive extreme pollution levels. Geoaccumulation indices signaled moderate to strong pollution, mainly by Pb and Zn. Ecological risk assessments revealed variable levels of heavy metal contamination, from low to very high, with potential ecological risk reflecting markedly elevated levels. This study underscores the imperative for soil remediation to rectify ecological imbalances in agriculturally affected soil constituents.
文摘Global industrialization over the past centuries has resulted in widespread contamination of the environment with organic and inorganic wastes and their pattern of disposal.The study aimed at isolating fungi from spent diesel contaminated soil around Ministry of Works in Aba,Abia State for biodegradation potentials on the soil properties.About four(4)fungal species were isolated from the five(5)sites using cultural and biochemical characteristics.The isolate was screened,and optical density measured using spectrophotometer.A total of 5 soil samples from each location(0-15 cm and 15-30 cm)were collected and homogenized to have composite sample.Samples were taken to the laboratory for analysis of soil physiochemical parameters,fungi count and biodegradable potential of the fungi using standard methods.Data obtained revealed that,physical property of the soil such as sand(85.20%±0.01%),silk(6.4%±0.01%)were lower than the control location except clay(17.39%±0.01%).Chemical properties revealed highest concentration of element such as pH(4.76±0.01),total nitrogen(0.18%±0.011%),total organic carbon(3.41±0.01),sodium(0.21±0.01),potassium(0.24±0.001),magnesium(4.41±0.015),calcium(5.21±0.015),organic matter(6.18±0.011),and available phosphorus(30.99±0.01).All elements in the study site were higher than the control site with an exception to sodium(Na),which was lower.Fungi isolate identified were Aspergillus niger,Trichoderma virdae,Aspergillus flavus,and Pencillum corylophlum.The degradation potential of fungi identified shows that consortium degraded 29%of diesel oil from the soil followed by A.flavus,T.virdae,A.niger and the least was T.corylophlum.The study concludes that despite indiscriminate disposal of spent diesel oil,the nutrient content was still higher than control and consortium performed well in degradation.
文摘Heavy metals have been viewed as hazardous environmental pollutants, and anthropogenic activities due to their high toxicity and persistent nature in the environment. Anthropogenic activities such as artisanal mining, industrial activities, improper usage of fertilizers and pesticides, and indiscriminate open waste disposal bring about an increase in the presence of heavy metals in the environment. In the Keffi Metropolis, different elements lead to land contamination which debilitates soil quality, plant survival, human well-being, and the environment as a result of extensive dispersion or quantity of heavy metals in the soil and water. In recent years, biochar has emerged as a promising soil amendment for mitigating heavy metal pollution due to its unique physicochemical properties. This paper provides the effects of softwood pellet biochar on the retention of heavy metals in contaminated soils. A microcosm experiment was carried out to investigate the effects of biochar on the retention of heavy metals in contaminated soils. This research aimed to give an overview of the effects of softwood biochar at different temperatures (550˚C and 700˚C) on the retention of heavy metals and metalloids released from the soil during water inundation. The results show that the addition of organic matter (grass chippings) minimizes heavy metal mobilization. Also, biochar at high temperatures is more effective than those at low temperatures. The expected outcome of the research analysis includes providing insights into the role of biochar in retaining heavy metal contamination and further understanding the use of biochar as a sorbent for the management of contaminated soil.
基金Project (2012BAC09B04) supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of ChinaProject (2010-277-027) supported by Science and Technology Foundation of Environmental Protection in Hunan Province,ChinaProject (2011SK3262) supported by Science and Technology Planning of Hunan Province,China
文摘The effects of five amendments such as acetic acid（AA）, citric acid （CA）, ethylenediamine tetraacetic acid （EDTA）, sepiolite and phosphogypsum on growth and metal uptake of giant reed （Arundo donax L.） grown on soil contaminated by arsenic （As）, cadmium （Cd） and lead （Pb） were studied. The results showed that the shoot biomass of giant reed was enhanced by 24.8% and 15.0%, while superoxide mutase and catalase activities slightly varied when adding 5.0 mmol/kg CA and 2.5 mol/kg EDTA to soil as compared to the control, respectively. The concentrations of As, Cd and Pb in shoots were remarkably increased by the addition of 2.5 mmol/kg AA and CA, 5.0 mmol/kg EDTA, and 4.0 g/kg sepiolite as compared to the control. The accumulations of As and Cd were also significantly enhanced in the above condition, while the shoot Pb accumulation was noticeably enhanced by amending with 4.0 g/kg sepiolite and 8.0 g/kg phosphogysum, respectively. The results suggested that AA, CA and sepiolite could be used as optimum soil amendments for giant reed remediation system.
基金Supported by National Programs for High Technology Research and Development of China(2007AA061001)Talent Introduction Project Supported by Hunan Agricultural University Project(07YT03)~~
文摘[Objective] The aim was to study on in-situ elimination effect on heavy metals in soil of the mining area by ramie （Boehmeria nivea （L.） Gaud.）. [Methods] Based on Xiangzhu No.3 and Zhongzhu No.1, we conducted research on heavy metals contents of plants growing in soil of Qibao Mountain orefield in Liuyang, Hunan Province, and on characteristics of enrichment and transfer of heavy metals （Cu, Pb, Cd, Zn） under influence of the two ramie species. [Result] It was concluded that trend of Cu content in different parts of ramie was as follows： rootskinleafbone; trend of Pb was rootleafskinbone; trend of Cd was rootskinboneleaf; the trend of Zn was rootskinboneleaf. In farmland A （with low content of heavy metal）, for per square meter of plough horizon, effect of Zhong 1 on heavy metals transferring volume and the period for restoration of the soil into national standard one （Category Ⅲ of Environmental Quality Standard for Soil） have been concluded. Specifically, for Cu, the corresponding values were 3 404.44 mg and 8.59 y, respectively; for Pb, the values were 3 638.5 mg and 13.52 y; for Cd, the values were 720.48 mg and 1.49 y; for Zn, the values were 37 324.8 mg and 0.67 y. [Conclusion] Soil contaminated by Cu, Pb, Cd, and Zn in orefield can be rapidly restored by growing ramie.
基金Supported by the National Natural Science Foundation of China(50874046)the National High-tech Research and Develop Program of China(863 Program)(2010AA065203)the Science and Technology Project of Education Bureau of Hunan Province,China(08A032)~~
文摘[Objective] To study the remediation efficiency of red mud on Pb, Zn and Cd in the heavy metal contaminated paddy soil of mine area, to clarify its remediation mechanism and fertilizer efficiency on heavy metal contaminated soil. [Method] The soil incubation experiment was conducted to study the effect of red mud on the pH values and electrical conductivity （EC）, and the remediation efficiency of red mud on lead （Pb）, zinc （Zn） and cadmium （Cd） in heavy metal contaminated soil. [Result] Red mud addition reduced the content of exchangeable Pb, Zn and Cd in the soil significantly. Compared with the control, when incubated for 30, 60 and 90 d with the red mud dosage of 4% （W/W）, the exchangeable Pb content was decreased by 39.25%, 41.38% and 50.19%; exchangeable Zn content was decreased by 49.26%, 57.32% and 47.16%; and exchangeable Cd content was decreased by 19.53%, 24.06% and 25.70%, respectively. The application of red mud had significant impact on the share of Pb, Zn and Cd contents in five forms, and different amounts of red mud application all reduced the proportion of exchangeable Pb, Zn and Cd to the total Pb, Zn and Cd. In addition, the proportion of exchangeable Pb, Zn and Cd to total Pb, Zn and Cd decreased with the increasing amount of red mud addition. [Conclusion] The study provided references for reasonable application of red mud and reduction of heavy metal pollution in paddy soil.
