包气带土壤DOM对硝酸盐迁移转化的影响——以张家口宣化区为例  

Effects of Dissolved Organic Matter from the Soil in Vadose Zone on Nitrate Migration and Transformation--A Case Study in Xuanhua District of Zhangjiakou City

作　　者：王星 虞敏达 苏婧[2] 郑明霞 任加国 WANG Xing;YU Min-da;SU Jing;ZHENG Ming-xia;REN Jia-guo(School of Earth Science&Engineering,Shandong University of Science&Technology,Qingdao,Shangdong 266590,China;Chinese Eesearch Academy qf Enuironmenial Sciences,Chinese Eesearch Academy of Erwironmental Sciences,Beijing 100012,China)

机构地区：[1]山东科技大学地球科学与工程学院,山东青岛266590 [2]中国环境科学研究院,国家环境保护地下水污染模拟与控制重点实验室,北京100012

出　　处：《四川环境》2023年第2期193-200,共8页Sichuan Environment

基　　金：国家重点研发计划项目“田园复合景观基础设施配置技术集成与示范”(2019YFD1101304)。

摘　　要：为了了解包气带土壤中溶解性有机质(DOM)的来源和组成结构,探索其对硝酸盐向地下水迁移转化可能作用过程的影响,对张家口市宣化区包气带土壤DOM进行了光谱分析。结果表明,包气带土壤中DOM受陆源和微生物源共同影响,主要组分为类腐殖质,占比达77%~85%。随着土壤深度的增加,类腐殖质不断被微生物分解转化为反硝化作用提供了充足的碳源,促进了包气带反硝化作用的发生,导致DOM的芳香性和腐殖化程度整体减小。此外,地下水中硝酸盐氮氧同位素(δ^(15)N-NO_(3)^(-)、δ^(18)O-NO_(3)^(-))组成特征(δ^(18)O:δ^(15)N=0.59)进一步证明了研究区包气带-地下水中硝酸盐的迁移转化主要受反硝化作用的影响。上述研究有助于了解包气带土壤中DOM的动态变化及其在自然环境中的生物地球化学效应,为进一步研究地下水硝酸盐污染提供基础参考。In order to understand the source and composition of dissolved organic matter(DOM)in the vadose zone soil,and to explore its influence on the possible process of nitrate migration and transformation into groundwater,DOM in the vadose zone soil in Xuanhua District of Zhangjiakou City was analyzed by spectral analysis.The results showed that DOM in all vadose zone soil profiles was influenced by both terrestrial and microbial sources,with humic-like substances accounting for 77%to 85%of vadose zone soil DOM.As soil depth increased,the decomposition and transformation of humic-like substances by microorganisms promoted the occurrence of denitrification,resulting in a decrease in the overall degree of humification and aromatization of DOM.Furthermore,the nitrogen and oxygen isotopic composition of nitrate in groundwater(δ^(18)O:δ^(15)N=0.59)demonstrated that the migration and transformation of nitrate in the vadose zone-groundwater in the study area is mainly influenced by denitrification.These findings contribute to a better understanding of the dynamic changes of DOM in vadose zone soil and its biogeochemical effects in the natural environment,and provide basic reference for future research on groundwater nitrate pollution.

关 键 词：地下水 硝酸盐污染 氮氧同位素 包气带土壤 溶解性有机质 

分 类 号：X523[环境科学与工程—环境工程]