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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]

[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]

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]