应用沸石分子筛稳定修复洞庭湖区重金属污染底泥及改良底泥的生态资源利用

Sediment in Dongting Lake Region, Hunan has been contaminated with heavy metals. A solution proposed to enable the sediment environmental responsible is its reuse for land application. Natural zeolite is highly recommended for the reuse of heavy metal contaminated sediment in Dongting Lake Region, due to its ability to take up readily available fractions of metals utilising ion exchange and its porous structure which can also minimise metal mobility. In this study, the effect of natural modified zeolite on heavy metal stabilisation in sediment and the influence of zeolite modified sediment on embankment soil-plant system will be studied in depth. Firstly, the effect of zeolite on metal partitioning and mobility in sediment will be studied. Then, change of physiochemical characteristics of the receiving embankment soil (including soil nutrional level and heavy metal speciation) caused by the application of zeolite-modified sediment will be investigated. Finally, the study will investigate the toxicity of the modified sediment to soil enzyme, microbes and plants and analyse the feasibility of ecologically utilising the modified sediment. The purpose of this project is to explore an accessable meathod to allow the reuse of heavy metal contaminated sediment economically and environmental-friendly in land application. This is to solve the problems encountered in sediment disposal and to enhance the ecosystem for slope vegetation in Dongting Lake Region.

湖南省洞庭湖区底泥重金属污染严重。处理污染底泥的一类环境友好型方法是将其处置后进行资源再利用。沸石分子筛由于其对金属离子的强交换吸收能力和其多孔性结构极有可能在洞庭湖重金属污染底泥资源化再利用方面起到重要作用。本项目拟深入研究改性沸石分子筛对污染底泥重金属的稳定和沸石改良后的底泥对堤岸土壤-植物系统的影响。项目将首先研究沸石分子筛对污染底泥中重金属分配和活性的影响；然后将研究应用改性沸石分子筛改良后的底泥对堤岸土壤基础理化性质（包括营养水平及重金属形态及分布）的影响；最后项目将研究改良底泥对堤岸土壤中土壤酶、微生物及植物的毒性，分析改良底泥资源化利用的可行性。该项目旨在探寻一种低成本和环境友好型的重金属污染底泥土地再利用的方法，以解决重金属污染底泥处置方面的困难，并有效改善洞庭湖区的水质和堤岸护坡植被的生态环境。

本项目拟以天然斜发沸石分子筛为稳定剂对洞庭湖区重金属污染底泥进行稳定修复,并深入研究改良底泥的生态毒性效应，综合评估经过沸石分子筛改良后的底泥回田利用的可能性。本项目通过完成天然沸石分子筛的改性、沸石分子筛对底泥中重金属的稳定化、改良底泥回田后土壤的基本理化性质和生态指标的变化，得出如下结论：1.未改性沸石分子筛与常规稳定剂石灰或二氧化锰相比不具有更优越的金属吸附稳定性能；2.通过盐或壳聚糖改性的沸石分子筛能有效稳定底泥中的重金属Pb、Zn和Cu，对重金属Cd的效果更优；3.通过盐改性的沸石分子筛回田后能有效缩短土壤和底泥中重金属Pb, Cu和Cd的滤出时间，降低滤出液中金属的浓度；4.通过壳聚糖改性的沸石分子筛比盐改性的沸石分子筛具有更好的生态相容性，其改良的底泥回田后微生物指标均有不同程度的增长，生物毒性效应减弱。以上结果对重金属污染底泥的修复和资源利用提供了新的技术方案，为河湖疏浚底泥的处理处置提供了新的途径，对实现废弃资源的新价值这一个科学难题提供了新的思路。