生物螯合剂EDDS与非生物螯合剂EDTA联合施用下植物提取土壤重金属及潜在环境风险

本文通过盆栽试验研究单一螯合剂EDTA、EDDS以及复合螯合剂的不同EDTA/EDDS配比对玉米和油菜作物重金属Pb、Cu、Cd的富集程度,并且通过淋滤实验分析各种螯合剂处理的土壤淋滤液重金属含量和土壤营养元素流失情况。结果表明:螯合剂的存在明显增加了植物重金属Pb、Cu、Cd的富集系数。植物重金属Pb富集系数在添加复合螯合剂配比3(EDTA/EDDS=1:2)时,达到最高;重金属Cu富集系数在添加复合螯合剂配比2(EDTA/EDDS=2:1)时,达到最高7.3;重金属Cd富集系数在添加单一螯合剂EDTA时达最高。土壤重金属淋滤液浓度在添加复合螯合剂不同EDTA/EDDS配比时比单一施用螯合剂要低。玉米组淋滤液中TN平均浓度高低依次为EDTA > EDDS > 配比3 > 配比1 > 配比2。油菜组淋滤液中TN平均浓度高低依次为EDTA > EDDS > 配比1 > 配比2 > 配比3。玉米组TP平均流失浓度高于空白对照组TP平均流失浓度72%,油菜组TP平均流失浓度高于空白对照组TP平均流失浓度54%。     

螯合剂诱导下污染土壤溶液中TOC和重金属的动态变化及其相关性

采用土培盆栽试验研究了EDTA,NTA(氨三乙酸)和EDDS(乙二胺二琥珀酸)三种螯合剂诱导下,土壤溶液中总有机碳(TOC)含量和重金属浓度的动态变化以及二者之间的关系.结果表明,施用5 mmol·kg-1螯合剂能极显著地增加土壤溶液中TOC的含量和Cu,Zn,Cd,Pb的浓度.土壤溶液TOC含量从第2天达最大后就随时间呈一阶指数衰减函数y=y0 Ae(x-x0)/t变化,衰减因子大小顺序为tEDTA>tNTA>tEDDS.土壤溶液中Cu,Zn,Cd和Pb浓度的动态变化也有与TOC相似的规律,并且两者呈显著线性正相关.结果还表明,螯合剂对重金属的活化能力与其相应金属螯合物的稳定常数lgKMe基本一致,为EDTA>EDDS>NTA,因此,在螯合诱导强化植物提取中NTA和EDDS的潜在环境风险比EDTA要小.     

Copper biosorption on immobilized seaweed biomass： Column breakthrough characteristics

The biosorption of copper by the brown seaweed Sargassum baccularia,immobilized onto polyvinyl alcohol(PVA)gel beads, was investigated with fixed-bed experiments.Laboratory-scale column tests were performed to determine breakthrough curves with varying flow rates and feed concentrations.A theoretical fixed-bed model,known as the Bohart-Adams equation,was evaluated in simulating the experimental breakthrough curves.The Bohart-Adams model qualitatively predicted the breakthrough trends.PVA- immobilized seaweed biomass beads were amenable to efficient regeneration with aqueous solution containing the chelating agent ethylenediaminetetraacetic acid(EDTA).The biosorbent retained most of its original uptake capacity over three cycles of use.The excellent reusability of the biosorbent could lead to the development of a viable metal remediation technology.