保水剂对土壤重金属镉形态及生物有效性的影响

发布时间：2017-12-28 03:37

本文关键词：保水剂对土壤重金属镉形态及生物有效性的影响　出处：《农业环境科学学报》2016年12期 　论文类型：期刊论文

【摘要】：基于保水剂所具有的较强重金属吸附能力,近年来已被作为重金属污染土壤的修复候选材料之一,为弄清保水剂如何影响重金属在土壤中的形态转化,通过向镉污染土壤中添加不同用量保水剂后的黑麦草盆栽试验,探讨保水剂(聚丙烯酸钠)对黑麦草吸镉以及对土壤镉形态转化的影响。结果显示,试验所用保水剂对溶液中重金属镉有较强的吸附能力,在镉浓度为200 mg·L~(-1)的溶液中,保水剂吸附镉可达120 mg·g~(-1)以上,添加保水剂可减少镉在黑麦草地上部的积累量。仅添加保水剂处理,60 d后土壤镉下降20%以上。添加保水剂并栽种黑麦草,可使土壤镉附加下降16%以上,培养过程中减少的土壤镉绝大部分被保水剂所吸附。黑麦草根系分泌物对镉的络合可促使难溶性镉向可溶性镉转化,而保水剂通过对可溶性镉的吸附降低了可溶性镉的浓度,促进镉由"残渣态→可氧化态→可还原态→酸溶态"的转化,两者共同促进了土壤镉的降低。添加保水剂一方面促进了土壤中难溶性镉向可溶性镉的化学转化,另一方面又减少了镉在植物体内的积累。因保水剂吸附的镉是否在一定时间后可重新释放出来被植物吸收还不清楚,将保水剂作为钝化剂正式用于修复镉污染土壤之前,还须通过长期的生物学试验加以验证。
[Abstract]:The strong adsorption capability of water retaining agent is based on in recent years has been regarded as one of the candidate materials for the remediation of heavy metal contaminated soil, in order to find out how to influence the speciation of heavy metals in the water of soil by pot experiment, Ryegrass with different amounts of added to the cadmium pollution in soil water holding agent, to explore the water retaining agent (sodium polyacrylate) the uptake of cadmium and cadmium effects on soil transformation. The results showed that the water retaining agent used in the experiment had strong adsorption capacity for heavy metal cadmium. In the solution of cadmium concentration of 200 mg. L~ (-1), the adsorption of cadmium by water retaining agent could reach 120 mg? G~ (-1). Adding water retaining agent could reduce the accumulation of cadmium in the upper part of rye grass. After only adding water retention agent treatment, the soil cadmium decreased by more than 20% after 60 d. Adding water retention agent and planting ryegrass can add more than 16% to cadmium in soil, and most of the reduced soil cadmium is adsorbed by water retention agent. The complexation of rye root exudates on cadmium can promote insoluble cadmium into soluble cadmium, and water retaining agent by adsorption of soluble cadmium decreased the concentration of soluble cadmium, promote the transformation from "residue, cadmium can be oxidized, reducible, acid soluble", both promoting lower into the soil cd. The addition of water retention agent promoted the chemical conversion of soluble cadmium to soluble cadmium in soil, on the other hand, it also reduced the accumulation of cadmium in plants. It is not clear whether the cadmium adsorbed by water retaining agent can be released again after a certain time. It is not clear that plants are absorbed by plants. If water retaining agent is used as a passivating agent, it will be verified by long-term biological tests before it is used to repair cadmium contaminated soil.
【作者单位】：扬州大学环境科学与工程学院;江苏省有机固体废弃物资源化协同创新中心;
【基金】：国家重大基础研究发展计划项目(2013CB127404) 国家自然科学基金项目(41301308,31272228,31000934)
【分类号】：X53
【正文快照】： 重金属污染已成为当前最受关注的土壤环境问题之一。据国家环保总局调查,中国农田镉污染面积在2003年即达到28×104hm2,镉超标农产品多达150万t[1],因此对土壤镉污染的治理迫在眉睫。土壤重金属污染修复方法主要包括物理、化学和生物三大类,其中物理修复包括物理热脱法、分离

【相似文献】