农业工程学报
農業工程學報
농업공정학보
2015年
7期
272-278
,共7页
重金属%土壤%污染调控%EDTA降解%环境风险
重金屬%土壤%汙染調控%EDTA降解%環境風險
중금속%토양%오염조공%EDTA강해%배경풍험
heavy metals%soils%pollution control%EDTA degradation%environmental risk
为分析乙二胺四乙酸（ethylenediaminetetraacetic acid，EDTA）在修复重金属污染土壤中的环境风险，通过田间调查和培养试验研究 EDTA 在不同重金属污染土壤中的降解及其残留。田间调查结果表明，乐昌试验田 EDTA 施用6 a后，表层土壤及深层土壤中均没有检出EDTA残留。佛冈试验田在施用EDTA 4个月后，表层土壤EDTA残留量为0.039～0.056 mmol/kg，仅为施入量的2%～5%，施用1 a后土壤中未检测到EDTA。翁源试验田在EDTA施用45 d后，表层土壤中EDTA残留量约为施用量的一半，1 a后残留量为施入量的2.6%，深层土壤监测到EDTA残留，但地下水中并没有检测到 EDTA，另外地下水中重金属含量并没有升高。因此，深层土壤对离子态和螯合态重金属具有较强的固定能力，可保护地下水免遭重金属的污染。培养试验结果表明，EDTA在土壤中降解遵循一级动力学方程，EDTA在赤红壤、褐土和重金属污染土壤中的降解速率常数分别为4.6×10-3、1.4×10-2和5.8×10-3，其降解的半衰期分别为71、25和53 d。EDTA在土壤中降解半衰期与土壤有机质含量和土壤阳离子交换量（cation exchange capacity）之间表现较好的相关性。微生物对 EDTA 在土壤中的降解具有显著的影响。总之，EDTA 可在土壤中降解，建议在中国重金属污染土壤修复过程中可采用EDTA强化修复技术，EDTA的环境风险是可控的。
為分析乙二胺四乙痠（ethylenediaminetetraacetic acid，EDTA）在脩複重金屬汙染土壤中的環境風險，通過田間調查和培養試驗研究 EDTA 在不同重金屬汙染土壤中的降解及其殘留。田間調查結果錶明，樂昌試驗田 EDTA 施用6 a後，錶層土壤及深層土壤中均沒有檢齣EDTA殘留。彿岡試驗田在施用EDTA 4箇月後，錶層土壤EDTA殘留量為0.039～0.056 mmol/kg，僅為施入量的2%～5%，施用1 a後土壤中未檢測到EDTA。翁源試驗田在EDTA施用45 d後，錶層土壤中EDTA殘留量約為施用量的一半，1 a後殘留量為施入量的2.6%，深層土壤鑑測到EDTA殘留，但地下水中併沒有檢測到 EDTA，另外地下水中重金屬含量併沒有升高。因此，深層土壤對離子態和螯閤態重金屬具有較彊的固定能力，可保護地下水免遭重金屬的汙染。培養試驗結果錶明，EDTA在土壤中降解遵循一級動力學方程，EDTA在赤紅壤、褐土和重金屬汙染土壤中的降解速率常數分彆為4.6×10-3、1.4×10-2和5.8×10-3，其降解的半衰期分彆為71、25和53 d。EDTA在土壤中降解半衰期與土壤有機質含量和土壤暘離子交換量（cation exchange capacity）之間錶現較好的相關性。微生物對 EDTA 在土壤中的降解具有顯著的影響。總之，EDTA 可在土壤中降解，建議在中國重金屬汙染土壤脩複過程中可採用EDTA彊化脩複技術，EDTA的環境風險是可控的。
위분석을이알사을산（ethylenediaminetetraacetic acid，EDTA）재수복중금속오염토양중적배경풍험，통과전간조사화배양시험연구 EDTA 재불동중금속오염토양중적강해급기잔류。전간조사결과표명，악창시험전 EDTA 시용6 a후，표층토양급심층토양중균몰유검출EDTA잔류。불강시험전재시용EDTA 4개월후，표층토양EDTA잔류량위0.039～0.056 mmol/kg，부위시입량적2%～5%，시용1 a후토양중미검측도EDTA。옹원시험전재EDTA시용45 d후，표층토양중EDTA잔류량약위시용량적일반，1 a후잔류량위시입량적2.6%，심층토양감측도EDTA잔류，단지하수중병몰유검측도 EDTA，령외지하수중중금속함량병몰유승고。인차，심층토양대리자태화오합태중금속구유교강적고정능력，가보호지하수면조중금속적오염。배양시험결과표명，EDTA재토양중강해준순일급동역학방정，EDTA재적홍양、갈토화중금속오염토양중적강해속솔상수분별위4.6×10-3、1.4×10-2화5.8×10-3，기강해적반쇠기분별위71、25화53 d。EDTA재토양중강해반쇠기여토양유궤질함량화토양양리자교환량（cation exchange capacity）지간표현교호적상관성。미생물대 EDTA 재토양중적강해구유현저적영향。총지，EDTA 가재토양중강해，건의재중국중금속오염토양수복과정중가채용EDTA강화수복기술，EDTA적배경풍험시가공적。
According to the bulletin of the national soil pollution reported by Ministry of Environmental Protection and Ministry of Land and Resources of the Peoples Republic of China, the total above standard rate is 16.1%in national soil, and above standard soils of Cd, Zn, Pb and Cu are 7.0%, 0.9%, 1.5%and 2.1%, respectively. Soil washing with chelating agents and phytoextraction by chelator-enhanced is potentially useful technique for remediating the heavy metal-contaminated soils. EDTA is the most frequently cited chelating agent in these techniques because of its strong chelating ability for different heavy metals. However, the slow degradation rate and persistence of residual EDTA in soil potentially increases the metal leaching risk which may cause groundwater contamination. But the environmental risk of EDTA reported in literature is from pot and column leaching experiments in laboratory scale. In order to understand the environmental risk of residual EDTA in the remediation of metal-contaminated soil, the field investigation and the incubation experiments were conducted to investigate the residue and degradation of EDTA in soil. The results of Lechang field investigation revealed that EDTA residue was not detected in the topsoil and deep soil after EDTA applied for 6 years. In Fogang field, the concentration of EDTA in soil was 0.039-0.056 mmol/kg soil, which was 2%to5%of the applied amount in the 4th month after application. However, the EDTA was not detected in soil after 1 year. In Wengyuan field, the concentration of EDTA in topsoil was approximately 50%of added amount (3.3 mmol/kg soil) after 45 d of EDTA application, while it was only 2.6% of added amount after application in one year. EDTA residue was detected in the deep soil. However, the EDTA was not detected in groundwater. In addition, the concentration of heavy metals in groundwater was not increased after EDTA application. The deep soils have considerable fixation capacity for the heavy metal-chelator complexes, which help preventing the metal-chelator complexes from leaching down to groundwater. Incubation experiments were carried out to evaluate the degradation of EDTA in different soils. The air-dried soil (2 kg with<5 mm particle size) was placed in plastic pots with the rate of 10 mmol/kg soil EDTA addition. Soils were incubated at room temperature and about 60%-70%soil water-holding capacity. Then soil samples were taken in 0, 3, 10, 20, 30, 50 and 72 d after incubation. The results indicated that degradation of EDTA in soils followed the first-order kinetic equation. Degradation rate constant of EDTA in latosolic red soil, cinnamon soil and metal-contaminated soil was 4.6×10-3, 1.4×10-2 and 5.8×10-3, and the half-life was 71, 25 and 53 d for each soil, respectively. The half-life of EDTA had a good correlation with the organic matter content and CEC in soil. Microorganisms had a marked influence on the degradation of EDTA in soils. The finding suggested that EDTA-enhanced remediation technology can be used on remediating heavy metals-contaminated soil, but the added amount should be controlled. As such, the environmental risk of EDTA is minimum.
