赣南稀土尾矿山土体硝态氮累积特征研究  

Study on the Characteristics of Soil Nitrate Nitrogen Accumulation of Rare Earth Tailing in Southern Jiangxi

作　　者：许哲 杨金玲[1,2] 赵越 张甘霖 XU Zhe;YANG Jinling;ZHAO Yue;ZHANG Ganlin(State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China;Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008 [2]中国科学院大学,北京100049 [3]中国科学院南京地理与湖泊研究所,南京210008

出　　处：《土壤学报》2024年第3期727-736,共10页Acta Pedologica Sinica

基　　金：国家重点研发计划项目(2018YFC1801801)资助。

摘　　要：稀土开采会造成大量浸矿剂(硫酸铵)残留在土壤中,高浓度铵态氮(NH_(4)^(+)-N)可能在生物化学作用下转化为硝态氮(NO_(3)^(-)-N)。为探明NO_(3)^(-)-N在稀土尾矿山土体内的含量及影响因素,明确硝酸盐污染程度,本研究选择赣南地区一个离子型稀土原地浸矿尾矿山,由表土分层采样至基岩面,并分析土壤NO_(3)^(-)-N及相关的理化性质。研究结果表明,尾矿山土体NO_(3)^(-)-N含量变异范围非常大(2.80~193.99 mg·kg^(–1)),其平均值为46.30±55.16 mg·kg^(–1),表层土壤NO_(3)^(-)-N含量范围为2.89~6.75 mg·kg^(–1),与自然土壤相近;表层以下土壤NO_(3)^(-)-N含量明显高于自然土壤。尾矿山土体深部含矿层土壤NO_(3)^(-)-N含量明显高于表层,NO_(3)^(-)-N含量随深度的分布规律与自然土壤相反,这是矿体部分残留大量浸矿剂造成的。土壤NH_(4)^(+)-N含量主导了NO_(3)^(-)-N的产生量,但NO_(3)^(-)-N在土体不同深度、山体不同部位的累积量还受降雨淋溶及NO_(3)^(-)-N迁移过程的控制。开采结束4年后,尾矿山内累积的NO_(3)^(-)-N仍不断向环境中释放。长期来看,尾矿山土壤中富集的NH_(4)^(+)-N将不断转化为NO_(3)^(-)-N并随水迁移,持续威胁生态环境及人类健康。本研究可为稀土原地浸矿场地土壤及下游水体污染的评价和治理提供理论基础与科学支撑。【Objective】Rare earth mining excessively increased the content of leaching agents(e.g.ammonium sulfate)in the soil.The high concentration of ammonium nitrogen(NH4+-N)may be converted into nitrate nitrogen(NO3--N)under active biochemical action,resulting in potential environmental risks,especially nitrate pollution of water bodies around tailings.Therefore,it is necessary to evaluate the content of soil NO_(3)^(-)-N,explore the influencing factors and understand the nitrate pollution degree of the rare earth tailings.【Method】We chose an ionic rare earth tailing after in-situ mining in southern Jiangxi province,which used ammonium sulfate as a leaching agent.Up to sampling,this mine had been closed for 4 years.We set three sampling points regularly from the top to bottom of this mine and collected soil profile samples in different layers from the topsoil to the bedrock.Soil samples were divided into two parts.One part was stored at a low temperature to analyze soil nitrate nitrogen and ammonium nitrogen.The other one was used for analyzing relevant physical and chemical properties after air drying.【Result】The results showed that the variation range of soil NO_(3)^(-)-N content in the tailing area was large(2.80 to 193.99 mg·kg^(-1)),with a mean of 46.30±55.16 mg·kg^(-1).The content of topsoil NO_(3)^(-)-N was 2.89-6.75 mg·kg^(-1),which was similar to that of natural soil.Also,the content of NO_(3)^(-)-N in the soil below surface layer was significantly higher than that in the natural soil.The soil NO_(3)^(-)-N of the ore-bearing layer in the deep profile was higher than that of the top layer.Moreover,the distribution of NO_(3)^(-)-N with depth was different from that of the natural soil and was mainly caused by a large number of leaching agents remaining in the ore body.NH_(4)^(+)-N content dominated the generation of NO_(3)^(-)-N and determined the upper limit of soil NO_(3)^(-)-N accumulation.The accumulation degree of NO_(3)^(-)-N in different soil layers and different parts of mountains was cont

关 键 词：氮转化 硝态氮分布 硝态氮迁移 离子型稀土 矿区土壤 

分 类 号：X53[环境科学与工程—环境工程] S151[农业科学—土壤学]