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This study presents a field trial of ex-situ solidification/stabilization of heavy metal contaminated soils using a new hydroxyapatite based binder SPC (superphosphate and calcium oxide). The field performance including electrical conductivity (EC), heavy metal and chemical oxygen demand (COD) leachability, and penetration resistance of stabilized soils up to 256 days after treatment is investigated. Moreover, acid neutralization capacity (ANC), metal speciation, and soil mineralogy analyses are performed to elucidate the heavy metal immobilization mechanisms. The results indicate that the stabilized soils have lower EC values than untreated soils, indicating the lower soluble salt contents in stabilized soils. Ex-situ treatment can significantly reduce acid soluble fraction contents and leachability of lead, zinc and cadmium in soils as a consequence. Decrease in COD leachability is observed during the curing period up to 256 days. Additionally, SPC stabilized soils give superior mechanical properties as indicated by their higher penetration resistance values as compared to the untreated soils. The improvement in ANC and reduction in acid soluble fraction resulting from the formation of phosphate-based precipitates are mainly responsible for the reduced heavy metal leachability of stabilized soils. Additionally, ex-situ SPC treatment is found to be effective in improving soil spatial homogeneity.

Arsenic (As)-contaminated paddy soil could result in elevated levels of As in rice plants and sequentially harm human health. The Fe

To explore the source and pollution characteristics of soil arsenic, mineralogy and chemical analysis methods were used to analyze the ore, waste rock, sediment, and river and soil samples around the mining area. Under a polarized light microscope, As-bearing mineral-arsenopyrite was found in the soil, ore, and waste rock around the Banbishan gold mine. Moreover, arsenopyrite in the waste rock has already experienced weathering and oxidation, and the oxidized arsenopyrite easily migrates and is released in the soil, which is potentially harmful. Because of the effect of mining transportation activities and indigenous smelting, arsenic was mainly distributed in the topsoil, at a depth of 0-20 cm, in the farmland on both sides of the road and in the places where villagers were gathered. The soil arsenic content in Xiaowulan Village and Gaozhangzi Village ranged from 7.2 to 196.2 mg·kg

The mining and smelting of arsenic-containing metal minerals, and the large-scale use of chemicals and pesticides, has resulted in the widespread pollution of soils in southwestern and southern China. In this study, the stabilizing effect of Fe-Ce oxide (FC) on three representative arsenic-contaminated soils was evaluated. The microscopic adsorption characteristics of FC and As(Ⅴ) were explored by scanning electron microscopy and energy disperse spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that FC can significantly reduce arsenic concentrations by 84.1%-98.3% during the Toxicity Characteristic Leaching Procedure (TCLP), and showed strong pH adaptability in alkaline soil. It efficiently transformed (non-)specifically sorbed arsenic (F1+F2) into hydrous oxides phases of Fe and Al (F3+F4). FC also significantly reduced available P by 47.13%-60.32% in different types of soil. FC can not only release As(Ⅴ) adsorption sites occupied by P in soils, but also effectively prevents non-point source pollution of the surrounding water. SEM-EDS and XPS analysis detected Fe, Ce, and As on the surface of As(Ⅴ) adsorption products, and As was mainly adsorbed on the surface of Fe atoms. The results of this study provide a scientific basis for soil arsenic stabilization in China.

Natural iron-containing minerals present in the geosphere in the form of crystalline minerals can be used as adsorption material for removal of arsenic from wastewater and remediation of arsenic-contaminated soils. In this paper, the adsorption and desorption of arsenic onto different iron-containing materials including hematite, limonite, siderite, ilmenite, magnetite, Fe

To ascertain absorption of arsenate and phenanthrene as well as their influence on carbon groups in excised roots of

pH is one of the most important factors affecting speciation and stabilization of arsenic and heavy metals in soil. In this study, Fe-Mn binary oxide (FMBO), synthesized by redox and precipitation reactions, was taken as the research object to evaluate its stabilization effects on As, Pb, Cd, Zn, and Cu in three types of soils under different pH conditions and to study the impacts on soil pH and buffering capacity. The results showed that the leaching concentrations of As and Pb were lower in the pH range of 3-9 (neutral and weak acidic) and 5-10 (neutral and weak alkaline); and Cd, Zn, and Cu were stable in the pH range of 7-11 (alkaline). The stability and stabilization effects of FMBO were better under alkaline conditions than acidic. In the optimal pH range, the optimum stabilization efficiency of FMBO could reach 92.7%, 100%, 97.0%, 88.7%, and 82.7% for As, Pb, Cd, Zn, and Cu, respectively. In addition, FMBO addition could increase soil pH and the acid buffering capacity moderately, which improved heavy metal stabilization and made it more suitable for acid soils and areas with more acid rain. From the correlation of contaminants and soil elements in the leachates, Fe played an important role in As stabilization, and pH had a great influence on the stabilization of Pb, Cd, Zn, and Cu.

In order to evaluate the effects and mechanism of in-situ cement solidification/stabilization (S/S) on heavy metal contaminated soils, leaching tests, speciation analysis, and microscopic analysis were conducted after cement treatment of a Pb, Zn, and Cd contaminated site in Baiyin, China. The leaching test results showed that cement could effectively stabilize Cd and Zn, which could reduce 99.5%-100% and 96.6%-98.8% of H

Pteris vittata L. can absorb and accumulate high arsenic levels in soil. To clarify the occurrence characteristics of pyrene (PYR) and arsenate (As) as well as their interaction in P. vittata L., the hosting and distribution rules of PYR were determined via two-photon laser scanning confocal microscopy (TPLSCM). The results showed that PYR addition resulted in obviously lower concentrations of total As in various parts of P. vittata, with a largest decrease of about 35% in the leaves and stem, and 20. 5% in the roots. PYR addition could also decrease the proportion of trivalent arsenic and increased that of pentavalent arsenate in different parts of P. vittata. The concentrations of trivalent and pentavalent arsenic in the leaves of P. vittata showed the largest decrement, which were 42.2% and 32.49%, respectively. Arsenate addition increased the accumulation of PYR in the root and stem of P. vittata by 9.8 µg and 139 ng per plant, respectively, while no obvious influence was found on the PYR in the leaves. Pyrene mainly attached to the cell membrane and other membrane structure such as nuclear membrane and organelle membrane, and there was less pyrene in the cytoplasm. There was little PYR in the phloem and cortex in the stem as well as palisade tissue and spongy tissue in leaves.

A pot experiment was carried out to study the effects of soil moisture on the growth and arsenic uptake of As-hyperaccumulator Pteris vittata L. The results showed that the remediation efficiency of As was the highest when the soil moisture was between 35%-45%. P. vittata grew best under 45% water content, and its aboveground and underground plant dry weights were 2.95 g x plant(-1) and 11.95 g x plant(-1), respectively; the arsenic concentration in aboveground and roots was the highest under 35% water content, and 40% content was the best for accumulation of arsenic in P. vittata. Moreover, controlling the soil moisture to 35%-45% enhanced the conversion of As(V) to As(III) in aboveground plant, and promoted arsenic detoxification in P. vittata. These above results showed that soil moisture played an important role in the absorption and transport of arsenic by P. vittata. The results of this study can provide important guidance for the large-scale planting of P. vittata and the moisture management measures in engineering application.

Certain plant species have been shown to vigorously accumulate some metals from soil, and thus represent promising and effective remediation alternatives. In order to select the optimum forms of nitrogen (N) fertilizers for the arsenic (As) hyperaccumulator, Pteris vittata L., to maximize As extraction, five forms of N were added individually to different treatments to study the effect of N forms on As uptake of the plants under soil culture in a greenhouse. Although shoot As concentration tended to decrease and As translocation from root to shoot was inhibited, overall As accumulation was greater due to higher biomass when N fertilizer was added. Arsenic accumulation in plants with N fertilization was 100-300% more than in the plants without N fertilization. There were obvious differences in plant biomass and As accumulation among the N forms, i.e., NH4HCO3, (NH4)2S04, Ca(NO3)2, KNO3, urea. The total As accumulation in the plants grown in As-supplied soil, under different forms of N fertilizer, decreased as NH4HCO3(NH4)2S04ureaCa(NO3)2KNO3CK. The plants treated with N and As accumulated up to 5.3-7.97 mg As/pot and removed 3.7-5.5% As from the soils, compared to approximately 2.3% of As removal in the control. NH4+ -N was apparently more effective than other N fertilizers in stimulating As removal when soil was supplied with As at initiation. No significant differences in available As were found among different forms of N fertilizer after phytoremediation. It is concluded that NH4+ -N was the preferable fertilizer for P. vittata to maximize As removal.

Experiments were carried out to investigate the effect of thermal enhanced soil vapor extraction (SVE) on benzene removal from sand, loam and clay and the mechanism. Compared to the routine control treatment, the benzene removal rates were improved by 13. 1% and 12. 3% and the remediation periods were reduced by 75% and 14%, from sand and loam respectively using thermal enhanced SVE. Thermal enhancement decreased the moisture content and increased the soil permeability of clay. On the surface of clay particles, absorption peaks of carboxyl and ethyl disappeared and the content of soil organic substances decreased significantly. Compared to the conventional SVE, the benzene removal rate was improved by 34% in clay soil treated by thermal enhanced SVE. For sand and loam, thermal enhancement could increase the removal rate by promoting the diffusion of benzene in the soil and achieve substantial removal of pollutants in a relatively short period of time. For clay, it could enhance the effect of SVE by reducing the absorption capacity between soil particle surface and contaminant and improving the performance of the gas diffusion in soil by decreasing the moisture content and increasing the soil permeability.

The problem of site contamination has become a focus in the environment protection field in the recent years. Decision support system (DSS) for remediation of contaminated sites is used for selecting the optimal remediation technologies and formulating economic and efficient remediation plans based on site investigation and risk assessment. This paper reviewed and analyzed the key steps in the decision-making process, including frames, models and methods. In addition, the modules and functions of more than 40 types of decision-making software in the world were evaluated and summarized. Aimed at the demand of site contamination in our country, a skeleton frame and feature were proposed in the paper, where the international experience in developed countries has been absorbed and learned.

Panax notoginseng is a valued traditional Chinese medical herb. In this study, the arsenic (As) contamination of soil in P. notoginseng plantation area in Wenshan (Yunnan, China) was investigated; the absorption and accumulation of soil As by the P. notoginseng was revealed; and the associated health risk was evaluated. The results revealed that the soil As concentrations ranged between 6.9-242.0 mg x kg(-1). Arsenic concentrations in 48% of the total soil samples were40 mg x kg(-1). The As concentrations in 24% of main root samples, 81% of fibrous root samples, 14% of stem samples, 57% of leaf samples, and 44% of flower/fruit samples were greater than the regulation concentration of 2.0 mg x kg(-1). Arsenic accumulation in the main root increased with the soil As concentration at soil As concentrations100 mg x kg(-1), but sharply decreased with the soil As concentration at soil As concentrations100 mg x kg(-1). With increasing soil As concentration, the total biomass of P. notoginseng and the main root biomass decreased. Calculating with the As concentration in different parts of Sanqi P. notoginseng plants, percent of the average ingestion rates of As with ADI regulated by FAO/WHO showed fibrous rootleaveflower/fruitmain rootstem. Based on the As concentration in the main root, the daily As intake accounted for a mean fraction of 12.83% (maximum 45.87%) of the acceptable daily intake specified by FAO/WHO,and the ratio increased with the increasing of soil As concentration. Arsenic contamination of soil and P. notoginseng at the plantation area of Wenshan should not be neglected, and effective strategies should be adopt to reduce As accumulation in the plant and human health risk.

In order to ascertain BTEX measurements of soils from industrial contaminated sites, static headspace, purge-and-trap and solid phase microextraction (SPME) combined gas chromatography were selected to determine BTEX in the soils. This method of SPME could not be used to analyze BTEX isomers in soils from highly contaminated sites because the high concentration of organic contaminants eroded the SPME probe head. The recoveries for added standard ranged from 95.2% - 98.2% for static headspace-GC and 99.2% - 101.3% for purge-and-trap-GC. When the soil samples contained low concentrations of BTEX (60 mg/kg), the concentration determined by purge-and-trap-GC was 12.6% - 37.6% higher than the value from static headspace-GC. For soil samples containing high concentrations of BTEX, the static headspace-GC result was higher than that from purge-and-trap-GC. The correlation trend lines of individual BTEX isomers to total BTEX were similar for both static headspace-GC and purge-and-trap-GC results.

An enclosed reactor was used to evaluate Fenton reagent, modified Fenton reagent, potassium permanganate and activated persulfate for removal of benzene, toluene, ethyl benzene, and xylene (BTEX) from soil at contaminated industrial coking sites. The results showed that Fenton reagent and modified Fenton reagent were the optimum oxidants for removing BTEX, and these oxidants decreased the concentration of BTEX in soils by 83% and 73%, respectively. The proportion of BTEX volatilized from the soil was4% in both cases, and the rates of BTEX removal from the whole system were 80% and 71%. More than 65% of xylene was removed after treatment with Fenton reagent and modified Fenton reagent. In contrast, benzene, toluene were more resistant to oxidation, and ethyl benzene was the most resistant of these compounds. The concentration of BTEX decreased to some extent when permanganate and activated persulfate were used as oxidants. However, the proportions of volatilized BTEX were 83% and 77% for permanganate and activated persulfate, respectively. This indicates that they could stimulate the desorption and volatilization of BTEX, while they were ineffective for removing BTEX from the environment.

Different oxidants were evaluated for removal of polycyclic aromatic hydrocarbons (PAHs) from contaminated soils at industrial coking sites with the use of simulating device, and the fate of pollutants during the treatment was investigated. Permanganate showed the highest PAHs removal rate (96.2%) of the oxidants studied. Most of the PAHs were oxidized and only1% of PAHs volatilized and transferred to the solvent. The removal of PAHs by activated persulfate reached 92%. Modified Fenton reagent could remove 80% of PAHs, and2% of PAHs volatilized and transferred to the solvent after treatment with activated persulfate and modified Fenton reagent. The efficiencies of hydrogen dioxide and Fenton reagent for removal of PAHs were both60% ,and up to 6% of PAHs volatilized and transferred to the solvent. In summary, permanganate and activated persulfate are the most effective and environment-friendly oxidants for removing PAHs from contaminated soils. The chemical oxidants could easily remove ANY, ANT, BaP, DahA, BghiP and IcdP, but FLE, CHR and Fla were relatively resistant to chemical oxidation.

Contamination of urban industrial lands is a new environmental problem in China during the process of upgrade of industrial structure and adjustment of urban layout. It restricts the safe re-use of urban land resources, and threatens the health of surrounding inhabitants. In the paper, the market potential of contaminated-site remediation was known through analysis of spatial distribution of urban industrial sites in China. Remediation technologies in the Occident which were suitable for urban industrial contaminated sites were discussed and compared to evaluate their superiority and inferiority. And then, some advices of remediation technologies for urban industrial contaminated sites in China were proposed.

Pb pollution on the surfaces of buildings and devices at a coking plant was studied. The objectives of this study were to determine the Pb content and its spatial variation on the surfaces, and to assess the potential health risk from this Pb. Ninety-four wipe samples were collected from 56 buildings and devices at the coking plant, and their Pb contents were determined. Surface Pb concentrations ranged from 0-538 micro x g/dm2, and concentrations in 78.7% of the samples exceeded the US Department of Housing and Urban Development (HUD) standard (2.69 microg/dm2). By area, the proportion of samples with concentrations greater than the US HUD standard were 78.9% in the office and living zone, 75.0% in the refining zone, 73.7% in the coking zone and 78.6% in the coke-gas zone. Among the various types of surfaces, the coke pusher had the highest average surface concentration of Pb. The average surface concentrations of Ph on common coking plant surface materials followed the order paintsbrickcementglass, and the concentrations in 94.4% of the wipe samples taken from paint surfaces exceeded the US HUD standard.

A pot experiment was carried out to study the root character and As accumulation of Pteris vittata L. affected by actinomycete PSQ, shf2 and bacteria Ts37, C13. The results indicated that growth of the fern was improved by the microorganisms. The biomass, root activity and root volume of shf2 treatment were 11.5 g/pot, 2.01 microg/(g x h), 38.3 mL, which were higher than those of other microorganisms treatments. Arsenic concentrations in the plants treated by the microorganisms were higher than that of the control treatment. The As concentration of leaves in Ts37 treatment was up to 837 mg/kg, 206% more than that of the control. The As concentration of root treated by shf2 is 427 mg/kg, 88% more than that of the control. The arsenic accumulation by the plant in microorganism treatments was higher than that of the control, especially shf2 treatment up to 5804 microg/pot, 136% more than that of the control. The phytoremediation efficiency of the fern in greenhouse experiment after 45d was from 8.9% to 11.3%. The ability of As-accumulation of Pteris vittata is greatly enhanced by application of microorganism, and actinomycete shf2 is proved as the perfect one.

To investigate influences of mining activities on heavy metal contamination and health risk in vegetable of mining-affected area, the present study was undertaken as a preliminary survey of As, Cd, Co, Cr, Cu, Ni, Pb and Zn concentrations of majority vegetables and soils in area affected by an ancient tin ore, Yunnan province. Based on the soil heavy metals investigated, average Nemero index of soil heavy metals reach 50.1, showed that vegetable fields were contaminated by heavy metals, especially As: average As concentration of soils could reach 1225 mg x kg(-1). Heavy metal concentrations in the edible portions of majority vegetables exceeded the national standards of China seriously, especially As and Pb, and the maximum of As and Pb concentrations (DW) could reach 856 mg x kg(-1) and 506 mg x kg(-1), respectively. Heavy metal concentrations among 3 kinds of vegetables decreased in following order: leaf vegetablesfruit vegetablesrhizome vegetables. Consumption of vegetables from the mining-affected area may pose extremely high health risk of As and Pb to local residents, which the exposed risk indexes could reach 158 and 13.3, respectively.

Fertilization has become one of the essential measures for enhancing efficiency of phytoremediating contaminated soils with heavy metal. In order to screen optimal P fertilizer for As-phytoremediation, a greenhouse study was conducted on the growth, As-accumulation and uptake of N, P and K by Pteris vittata L. in As-contaminated soils with different forms of P fertilizers. The results indicated that the biomass of plant with As addition decreased compared to no As-addition treatments except fused calcium magnesium phosphate (CaMg-P) treatment. The plants in As addition soils with CaMg-P, calcium dihydrogen phosphate (CDP) and di-ammonium phosphate (DAP) had higher biomass than those with other P fertilizer and control (0.83 g/pot). The As accumulations of plant aboveground in As addition soils are in order of CDPCaMg-PDAPPotassium Phosphate MonobasicMonosodium phosphatecontrolCalcium superphosphate. The efficiency of As removal from As addition soils with CDP was the highest, 7.28%. Thus it can be seen the ability of phytoremediation using P. vittata could be improved by P fertilization, which CDP should be recommended preferentially and CaMg-P and DAP is considered as replaceable fertilizer for sake of pH, N, P and available As in phytoremediated soils.

Description de l'identification structurelle. C'est le premier Hbcs homozygote trouve en Chine