猪粪源溶解性有机质对锰矿区耕地土壤中镉迁移的影响  

Effect of Dissolved Organic Matter from Pig Manure on Cadmium Migration in Tillage Soil in a Manganese Mining Area

作　　者：张维 侯孟彬 伍诗宇 王星敏 ZHANG Wei;HOU Mengbin;WU Shiyu;WANG Xingmin(Department of Land Resources Management,Chongqing Technology and Business University,Chongqing 400067,China;School of Environment and Resources,Chongqing Technology and Business University,Chongqing 400067,China)

机构地区：[1]重庆工商大学土地资源管理系,重庆400067 [2]重庆工商大学环境与资源学院,重庆400067

出　　处：《环境科学研究》2024年第9期1997-2005,共9页Research of Environmental Sciences

基　　金：重庆市教委科学技术研究项目(No.KJQN202100807,KJQN202300832);重庆市自然科学基金项目(NO.CSTB2023NSCQ-MSX0106)。

摘　　要：镉(Cd)是迁移潜力最大的重金属元素之一。土壤中Cd迁移过程及影响因素的研究对于土-水生态系统中Cd的环境风险评估及修复治理有重要意义。为探求外源富碳有机质对金属矿区污染耕地土壤中Cd迁移的影响,开展原状土柱淋洗试验,考察猪粪源溶解性有机质(DOM)的引入(232 mg/L)对胶体结合态Cd(C-Cd)和水溶态Cd(D-Cd)迁移过程的差异及影响机制。结果表明:①猪粪DOM引入前,土壤胶体是Cd迁移的主要载体,胶体浓度是影响总镉(T-Cd)和C-Cd浓度动态变化的主要因素;猪粪DOM引入后,原状土柱淋洗过程中T-Cd和C-Cd的迁移量分别是对照阶段的1.8倍和2.2倍,pH成为影响Cd迁移的关键因素。②猪粪DOM的引入主要通过提升溶液pH,促进土壤胶体的迁移(迁移量较对照阶段增加了68.4%)进而增加C-Cd的迁移量(较对照阶段增加了124.4%)。同时,pH的增加也抑制了Cd^(2+)的解吸,导致D-Cd迁移量较对照阶段减少了41.2%。③猪粪DOM引入后的淋洗过程中,DOM通过提升土壤胶体Cd富集系数(由32.6mg/kg增至43.4mg/kg),进一步提升了土壤胶体对Cd迁移的支配作用,T-Cd中C-Cd的占比高达90.1%。因此,在农用地Cd污染土壤或场地污染土壤修复过程中涉及外源富碳有机质(如畜禽粪便、城市污泥、堆肥/生物质炭)应用时,应重点关注外源DOM促进胶体结合态Cd迁移进入浅层地下水的环境风险。Cadmium(Cd)is one of the most labile heavy metals in the environment.The study of Cd transport dynamics and influencing factors is of great importance for the risk assessment of Cd as well as Cd remediation in soil-water ecosystem.Leaching experiments were conducted in the intact soil column to explore the potential impact of exogenous dissolved organic matter(DOM)on the mobilization and transport of Cd in contaminated arable soil in a metallic mining area.The mechanisms of pig manure-derived DOM(232 mg/L)on the transport kinetics and fluxes of colloid-associated Cd(C-Cd)and dissolved Cd(D-Cd)in the absence and presence of manure DOM were highlighted.The results indicated that soil colloids are the major carriers of Cd transport in the absence of manure DOM.Colloid concentration was identified to be the key factor responsible for the dynamics of total Cd(T-Cd)and C-Cd.In contrast,the transport fluxes of T-Cd and C-Cd during soil column leaching in the presence of manure DOM were 1.8 and 2.2 times of the transport fluxes of T-Cd and C-Cd during soil column leaching in the absence of manure DOM,respectively.After the injection of manure DOM,solution pH became the key factor affecting Cd leaching kinetics.The major mechanism for these changes was an increase in solution pH in the presence of manure DOM.This effect facilitated the release of soil colloids with an increase by 68.4 and subsequent increased transport of C-Cd by 124.4%.Meanwhile,the increase in solution pH suppressed the desorption of Cd from soil surface,resulting in a 41.2% decrease in the transport flux of D-Cd.Additionally,the enrichment factor of Cd on soil colloids increased from 32.6 mg/kg to 43.4 mg/kg due to the injection of manure DOM,resulting in an enhancement of the dominant role of soil colloids in Cd transport as implied by the increased proportion of C-Cd in T-Cd up to 90.1%.Consequently,due attention should be paid to the contamination risk of shallow groundwater potentially resulted from the intensified colloid-facilitated Cd transport

关 键 词：镉(CD) 迁移 溶解性有机质(DOM) 猪粪 土壤胶体 

分 类 号：X53[环境科学与工程—环境工程]