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The objective of this paper is to elucidate the environmental capacity of heavy metal in soils of an urbanization gradient zone of Urumqi City, a total of 88 surface soil samples were thereby collected from the typical gradient zone including urban, suburban, rural and wasteland areas, and heavy metal contents of Cd, Hg, As, Pb, Cu, Ni, and Zn in soils were measured, and the characteristics and spatial distribution pattern of the environmental capacity of soils was analyzed based on the GIS and the method of comprehensive environmental index (PI). As a result, the investigation showed that heavy metal contents in topsoil of the urbanization gradient zone along the areas of urban, suburban, rural and wasteland differed in a certain degree, and Hg had been evidently enriched in soils of all the areas of the gradient zone; the mean PIs of heavy metals in soils of the urbanization gradient zone were arranged in order of decreasing magnitude: rural> suburban>wasteland> urban, the relevant environmental capacity of all the areas being mediocre. As to the spatial pattern, individual environmental capacity index of each single heavy metal in soils of those areas was different, and low PI mainly distributed in the urban area, which indicated a significant impact of urbanization on soil environmental capacity. The dynamic annual capacity and static annual capacity of each heavy metal were in order of decreasing magnitude: Zn> Ni> Pb> Cu> As> Hg> Cd. In addition, the dynamic annual capacity of heavy metals in soils of each arear of the gradient zone showed a trend 20 a > 40 a > 60 a > 80 a > 100 a. The aver-age dynamic annual capacity of every kind of heavy metal in soil of each gradient zone area was greater than the static annual capacity in fixed number of years, and as a whole, the environmental capacity of soils tended better. [ABSTRACT FROM AUTHOR]

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Soil heavy metal pollution has become one of the hot environmental issues of global concern, and its treatment and remediation has become a major scientific and technological demand for social and economic development. Soil animal earthworm-plant remediation has become a new way to control soil heavy metal pollution. Based on a large number of documents at home and abroad, this paper expounds the important role of earthworms in phytoremediation of heavy metal contaminated soil from three aspects, including changing soil physical and chemical properties from earthworm activities to accelerate phytoremediation of heavy metals, promoting phytoremediation of heavy metals by earthworm and microbial interaction, change of heavy metal morphology by earthworm secretion and excrement to affect phytoremediation of heavy metals, so as to provide theoretical reference for subsequent related research. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the bibliometrics analysis, this paper firstly identifies that the research focus of humic acid-based material immobilization field is on immobilization remediation effect and remediation mechanism.Based on the two research focuses identified, the heavy metals in soil were classified into those in the form of cations（e.g.Cd, Pb, Hg, etc.) and those in the form of oxygen anions（e.g.As and Cr),and the immobilization effects and immobilization mechanisms of humic acid and humic acid-based materials on soil heavy metals were systematically reviewed.Humic acid and humic acid-based materials have highly effective to immobilize soil heavy metals, and their immobilization mechanisms mainly include complexation, ion exchange, electrostatic interaction, redox and co-precipitation with introduced modified materials.This review further points out the shortcomings of humic acid-based materials in immobilization remediation technology in terms of practical applications and provides an outlook on future research directions, in order to provide scientific references for in situ immobilization remediation of heavy metal contaminated soils. [ABSTRACT FROM AUTHOR]

Most of the heavy metal-related deposits are distributed in watersheds of mountainous areas, and the enrichment of soil heavy metals were affected by both natural high background and anthropogenic source in the area. It is particularly important to formulate precaution countermeasures to accurately identify and quantify the source of soil heavy metal pollution in the ore-concentrating area. This paper studies the surface soil of a small basin in Beishan Reservoir which was rich in ores. Based on the evaluation of the heavy metal accumulation degree, the pollution sources identification and their contributions to soil heavy metals were studied by multiple methods including field investigation, multivariate statistical analysis, positive matrix factorization(PMF), spatial analysis, and other methods. Conclusively, the accumulated Cu and Cd in the top soil were higher than other heavy metals, the Cu and Cd average contents were 3.05, 3.47 times as high as the regional background value, and exceeded the soil risk screening values. About 10% of samples reached the level of moderate to severe enrichment. The heavy metal pollution sources in the topsoil were jointly affected by natural geological background, mining activities, and agricultural activities source. The contribution rates of mining activities to Cu and Cd are 68.92% and 56.31%, and natural geological backgrounds also contribute 21.05% and 38.35% to them. The natural source contributed most to As, Cr, and Ni, with contribution rates of 83.13%, 72.59%, and 78.76%, respectively. Hg mainly comes from agricultural activities, and its contribution rate was 81.79%. Zn and Pb were affected by both material migration and natural geological background. The reliability and rationality of the analytical results for the heavy metal pollution sources can be improved by the mutual verification of the combination using different methods. [ABSTRACT FROM AUTHOR]

Isitu passivation repair technology for heavy metals is a promising processing technology. This technology mainly adds exogenous remediation agents to the contaminated soil, and undergoes a series of reactions such as adsorption, ion exchange, precipitation, oxidation-reduction and other heavy metal ions to convert heavy metals into a more stable form and fix them in the soil, thereby preventing heavy metals from passing through plant roots migrate to the upper part of the ground to achieve the purpose of repairing the soil. This paper systematically expounds the effect and repair mechanism of passivation technology, deeply analyzes the types of passivation materials, and further puts forward the problems to be solved in passivation repair technology from the practical application, and prospects for future research directions. [ABSTRACT FROM AUTHOR]

Combined with the existing research, the research progress of biochar remediation of heavy metal pollution is reviewed. This paper focuses on the mechanism of biochar immobilization of heavy metals in soil, the effect of biochar on the absorption of heavy metals by plants, the research results of the application of biochar in field engineering, and the risks and shortcomings o£ biochar as a soil improver. Finally, it is hoped that on the premise of meeting safe production, the popularization of biochar should be promoted in agricultural production, rather than limited to scientific research. Start the life cycle assessment of biochar and establish a biochar life cycle database to provide a comprehensive and effective scientific basis for the future use of biochar. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to take the open-pit coal mining area in southern Karamari mountains as an example, the contents, enrichment characteristics and spatial distribution of heavy metals in typical desert plant Reaummuria soongorica（Rs）and surrounding soil were analyzed. The pollution status of six heavy metals, zinc, copper, chromium, lead, mercury and arsenic (Zn, Cu, Cr, Pb, Hg, As) was evaluated and their sources were explored. [Method] Mathematical statistics and GIS methods were used to analyze the enrichment characteristics and spatial distribution of heavy metals in bipachai, analyze the pollution sources and evaluate the potential ecological risk. [Result] The over-standard rates of Cr, Pb and As in soil samples were more than 70%, and the average values exceeded the background values of Changji. The over-standard rates of Hg in Rs samples were 23.08%. The enrichment coefficient (3.658) of Hg in Rs was much higher than that of other elements, indicating that Rs has a strong tolerance to Hg. Except for Pb, the retention rate of other elements was positive, indicating that there was a certain tolerance in the root of Rs. Zinc and copper mainly came from crustal sources, while other elements were affected by both human and natural factors, especially Hg, which was heavily affected by disturbance in mining area and seriously polluted. Potential ecological hazard assessment results showed that in soil and plant, Zn, Cu, Cr, Pb, As five elements were relatively light pollution, Hg pollution was more serious. The distribution of Cu, Cr and As in Rs was similar, which might come from same sources. The enrichment ability of Rs to As was related to the content of As in soil. [Conclusion] The content of elements exceeding the standard in the soil of the study area was low in Pipa. At the same time, Pipa had a certain tolerance and can be used as a dominant species for ecological restoration. [ABSTRACT FROM AUTHOR]