脱硫石膏修复土壤典型污染物形态转化及生物有效性研究

A lot of attention has been drawn on the beneficial utilization of flue gas desulfurization gypsum (FGDG), one of coal combustion byproducts from coal-fired power stations. Changing of physico-chemical properties of soil is predictable followed by moderate FGDG added, which may affect the environmental behavior of pollutants in soil. However, few researches have been focused on the speciation, mobility and bioavailability of pollutants in soil caused by adding of FGDG. In this proposal, the influence of FGDG on environmental behavior of As, Cd compounds in the soil will be studied with the appropriate experimental facilities and the mechanism will be investigated by analysis of soil physico-chemical properties. The research contents can be concluded as follows: (1) Disrupting of soil physico-chemical properties by addition of FGDG; (2) Influence of mobility of As, Cd in the soil remediated by FGDG under various simulated rainfall and irrigation conditions; (3) Species of As, Cd compounds in the soil remediated by FGDG; (4) Regulating mechanism by FGDG to bioavailability of As, Cd compounds in the remediated soil. This proposal will be significant for the reuse of solid waste, soil remediation and food safety.

脱硫石膏是燃煤电厂的主要固体废弃物，其综合利用一直受到广泛关注。土壤中添加脱硫石膏后，许多理化性质会发生改变，如pH、Eh、阳离子吸附容量、渗透性等，进而影响土壤中污染物的环境行为。目前，脱硫石膏已被成功应用于土壤环境修复，但基于此修复引起的土壤微界面理化性质变化及对土壤中典型污染物环境行为影响的研究还很缺乏。本课题拟通过设计合适的实验装置，研究客入脱硫石膏对典型污染物砷(As)和镉(Cd)在土壤微环境中的形态分布及生物有效性影响机制，具体内容包括：(1)脱硫石膏组分、添加量、添加方式对土壤微环境理化性质扰动机制；(2)脱硫石膏修复土壤农田淋溶过程中土壤-植物-间隙水As、Cd微界面迁移特征；(3)脱硫石膏修复土壤氧化还原环境变化及对As、Cd赋存形态调控；(4)客入脱硫石膏对土壤中As、Cd生物有效性影响过程。本研究旨在为固废资源化利用、土壤修复、食品健康研究提供参考依据。

脱硫石膏是燃煤电厂的主要固体废弃物，其资源化利用利用一直受到广泛关注，土壤修复也是当前研究的热点问题。目前，脱硫石膏已被成功应用于土壤环境修复，但基于此修复引起的土壤微界面理化性质变化及对土壤中典型污染物环境行为影响的研究还很缺乏。基于此，本课题主要开展了以下几方面的研究： (1)脱硫石膏中砷(As)和汞(Hg)等污染物的分布特征和赋存形态；(2) 脱硫石膏修复对土壤理化性质的影响规律；(3) 脱硫石膏土壤修复系统农田淋溶过程中土壤-植物-间隙水As、Hg微界面迁移特征；(4)脱硫石膏修复对土壤中As、Hg赋存形态及生物可利用性的影响规律及机理。研究发现，(1)脱硫石膏中As、Hg总体浓度水平不高，分别为1-10 μg g-1和0.1-3.0 μg g-1，平均浓度均低于土壤三级质量标准；(2)脱硫石膏添加能有效调节盐碱土的pH值，土壤团聚性的增加能提高土壤氧化还原电位、阳离子吸附交换容量；(3)脱硫石膏添加降低了土壤中As、Hg的淋出性；(4)脱硫石膏添加能够有效降低土壤中As、Hg的生物可利用形态。本研究将为固废资源化利用、土壤修复、食品健康研究提供数据支持。