The effect of low-molecular-weight organic-acids(LMWOAs)on treatment of chromium-contaminated soils by compost-phytoremediation: Kinetics of the chromium release and fractionation  

作　　者：Huixia Chen Junfeng Dou Hongbin Xu 

机构地区：[1]College of Water Sciences, Beijing Normal University [2]Key Laboratory of Green Process and Engineering, Chinese Academy of Sciences [3]National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering,Chinese Academy of Sciences

出　　处：《Journal of Environmental Sciences》2018年第8期45-53,共9页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos. 21376251 and 21406233);the National Basic Research Program (973) of China (No. 2013CB632600)

摘　　要：A soil–plant biological system was developed from chromium（Cr） polluted soil treated by the compost-phytoremediation method. The transformation and migration of the Cr in this system is comprehensively studied in this research. The results illustrated that the co-composting treatment can reduce the Cr availability from 39%（F1 was about 31% of total, F2 was about 8% of total） to less than 2% by stabilizing the Cr. However, herbaceous plants can accumulate the concentrations of Cr from 113.8 to 265.2 mg/kg in the two crops,even though the concentration of soluble Cr in the substrate soil was below 0.1 mg/L.Cr can be assimilated and easily transferred in the tissues of plants because the lowmolecular-weight organic-acids（LMWOAs） derived from the plant root increase the bioavailability of Cr. The amount of extracted Cr dramatically increased when the organic acids were substituted in this order： citric acid 〉 malic acid 〉 tartaric acid 〉 oxalic acid 〉acetic acid. On average the maximum（147.4 mg/kg） and the minimum（78.75 mg/kg） Cr were extracted by 20 mmol/L citric acid and acetic acid, respectively. The desorption of Cr in different acid solutions can be predicted by the pseudo second-order kinetics. The exchangeable Cr, carbonate-bound Cr, and residual Cr decreased, while Fe–Mn oxide bound Cr and organic bound Cr increased in the soil solid phase. According to the experimental results, the organic acids will promote the desorption and chelation processes of Cr, leading to the remobilization of Cr in the soil.A soil–plant biological system was developed from chromium（Cr） polluted soil treated by the compost-phytoremediation method. The transformation and migration of the Cr in this system is comprehensively studied in this research. The results illustrated that the co-composting treatment can reduce the Cr availability from 39%（F1 was about 31% of total, F2 was about 8% of total） to less than 2% by stabilizing the Cr. However, herbaceous plants can accumulate the concentrations of Cr from 113.8 to 265.2 mg/kg in the two crops,even though the concentration of soluble Cr in the substrate soil was below 0.1 mg/L.Cr can be assimilated and easily transferred in the tissues of plants because the lowmolecular-weight organic-acids（LMWOAs） derived from the plant root increase the bioavailability of Cr. The amount of extracted Cr dramatically increased when the organic acids were substituted in this order： citric acid 〉 malic acid 〉 tartaric acid 〉 oxalic acid 〉acetic acid. On average the maximum（147.4 mg/kg） and the minimum（78.75 mg/kg） Cr were extracted by 20 mmol/L citric acid and acetic acid, respectively. The desorption of Cr in different acid solutions can be predicted by the pseudo second-order kinetics. The exchangeable Cr, carbonate-bound Cr, and residual Cr decreased, while Fe–Mn oxide bound Cr and organic bound Cr increased in the soil solid phase. According to the experimental results, the organic acids will promote the desorption and chelation processes of Cr, leading to the remobilization of Cr in the soil.

关 键 词：CHROMIUM PHYTOEXTRACTION Desorption Release kinetics Speciation 

分 类 号：Q1[生物学—普通生物学]