重金属在燃煤烟气脱硫石膏改良盐碱土壤中迁移的实验研究  

Experimental investigation on distribution profiles of heavy metals in the desulfurization gypsum amended saline and sodic soils

作　　者：王淑娟[1] 陈群[1] 李彦[1] 张宁[1] 赵博[1] 禚玉群[1] 陈昌和[1] 

机构地区：[1]清华大学热能工程系,热科学与动力工程教育部重点实验室,盐碱地区生态修复与固碳研究中心,北京100084

出　　处：《生态环境学报》2013年第5期851-856,共6页Ecology and Environmental Sciences

基　　金：国家科技支撑计划(2013BAC02B06);清华大学自主科研计划(20101081776)

摘　　要：改良盐碱地对于保障我国粮食安全、生态环境保护及经济社会可持续发展具有非常重要的意义。近20年来,火力发电厂燃煤烟气脱硫石膏已成功地应用于我国北方盐碱地的改良。作为燃煤电厂的废弃物,脱硫石膏含有一些重金属元素,这些重金属元素随着脱硫石膏改良盐碱地而进入土壤中。目前,还很少有针对这些重金属对土壤环境影响的研究。为了评估脱硫石膏——特别是脱硫石膏中携带的重金属——在改良盐碱地后对作物和生态环境可能造成的影响,从而为今后大面积示范推广脱硫石膏改良盐碱地提供依据,以燃煤烟气脱硫石膏作为改良剂,测量了不同脱硫石膏添加比例下盐碱土的土壤碱化度（ESP）、酸碱度（pH值）和电导率（EC）随脱硫石膏添加量变化。通过土柱淋滤实验,分析研究了加入不同重量比例脱硫石膏的不同盐碱土壤层中重金属Pb、Cd、Cr、As、Hg含量分布。结果显示,加入脱硫石膏的盐碱土壤pH值、电导率值、及碱化度有明显降低,表明脱硫石膏对于盐碱土具有明显的改良作用。总体而言,脱硫石膏的加入并未引起土壤重金属含量的显著变化。随着脱硫石膏的加入,在60~80 cm土层中镉（Cd）含量增加、汞（Hg）含量在40~60 cm土层中增加、而土柱其余各层中的铅（Pb）含量均明显低于0~20 cm表层土壤。这些重金属的不同分布状态是其在土壤中迁移特性决定的。重金属在各土层中的最高含量均符合GB 15618—1995国家土壤环境安全标准,表明脱硫石膏在改良盐碱土过程中不会导致土壤重金属污染而影响土壤环境质量。Flue gas desulfurization （FGD） gypsum has been applied as an amendment to saline and sodic soils for nearly two decades. It has been proven that FGD gypsum is effective for reclaiming sodic soils. However, as a byproduct from wet desulfufization process, FGD gypsum thus contains some heavy metals either from coal or from limestone. The heavy metals that have entered the soils amended with FGD gypsum may be leached to the soil environment. To date, very few data are available to show the potential environmental risks of the heavy metals introduced by FGD gypsum on the soils. The migration of these extra heavy metals in the soils remains unclear. In this paper, soil column leaching experiments were carried out to investigate the distribution profiles of heavy metals, such as Pb, Cd, Cr, As and Hg, in different soil horizons. The results showed that the pH value, total dissolved salts （TDS） and exchangeable sodium percentage （ESP） significantly decreased in the FGD gypsum amended soils compared with those in the unamended soil. No significant accumulation of heavy metals was found in the soils with the introduction of FGD gypsum. However, Cd and Hg contents increased slightly in 60-80 cm and 40-60 cm horizons respectively, while Pb content in each horizon were significantly lower than those in the top surface horizon. Moreover, the contents of the heavy metals in the soils were well complied with the Environmental Quality Standard for Soils in China （GB 15618--1995）, which implied that FGD gypsum would not deteriorate the soil environmental quality.

关 键 词：土柱试验 重金属 脱硫石膏 盐碱土壤 

分 类 号：S156.4[农业科学—土壤学]