山前农业区HNO_(3)对碳酸盐岩风化的扰动影响——以清水河上游为例  

Perturbing Effects of HNO3 on Carbonate Weathering in an Premontane Agricultural Region,an Example from the Upper Reaches of the Qingshui River

作　　者：刘伟 张海岛 谢银财 张恒星 刘昊洋 杨国丽[1] 李军 马立山[1] LIU Wei;ZHANG Haidao;XIE Yincai;ZHANG Hengxing;LIU Haoyang;YANG Guoli;LI Jun;MA Lishan(Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources,Hebei University of Architecture,Zhangjiakou 075000,China;Key Laboratory of Karst Dynamics,Ministry of Natural Resources/Guangxi,Institute of Karst Ceology,Chinese Academy of Geological Sciences,Guilin 541004,China;Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Science,Shijiazhuang 050061,China)

机构地区：[1]河北建筑工程学院/河北省水质工程与水资源综合利用重点实验室,张家口075000 [2]中国地质科学院岩溶地质研究所,自然资源部/广西岩溶动力学重点实验室,桂林541004 [3]中国地质科学院水文地质环境地质所,石家庄050061

出　　处：《内蒙古农业大学学报（自然科学版）》2024年第6期40-49,共10页Journal of Inner Mongolia Agricultural University(Natural Science Edition)

基　　金：国家重点研发计划项目(2019YFC0409201);广西自然科学基金项目(2021GXNSFBA220065);校级研究生创新基金项目(XY2025001)。

摘　　要：碳酸盐岩是全球最大的碳库,定量评价山前农业区HNO_(3)对碳酸盐岩风化的影响对深入理解全球碳循环具有重要科学意义。2022年7月于清水河山前农业区河段13个监测点进行了样品采集,对常规水化学和稳定同位素指标(δ~2H-H_2O、δ~(18)O-H_2O、δ~(15)N-NO_(3)^(-)和δ~(18)O-NO_(3)^(-))进行检测,基于MixSIAR模型确定山前农业区河水中NO_(3)^(-)主要来源,利用水文地球化学证据揭示NO_(3)^(-)的关键污染控制过程。在此基础上,利用碳酸盐岩溶解的化学计量关系定量HNO_(3)扰动的碳酸盐岩风化及其对碳汇通量的影响。结果表明:清水河山前农业区河段水体呈弱碱性,水化学类型为HCO_(3)-Ca·Mg水,主导离子主要受方解石和白云石溶解控制。河水NO_(3)~–污染源贡献率为大气沉降(0.18%±0.06%)<硝态氮肥(0.40%±0.11%)<土壤有机氮(9.30%±4.50%)<铵态氮肥(16.10%±9.00%)<粪便和污水(74.00%±13.00%)。含NH_4~+污染物对河水中NO_(3)^(-)贡献率达99.40%。微生物硝化作用将NH_4~+转化为HNO_(3)后,生成的中间产物HNO_(3)优先且快速参与到碳酸盐岩风化中。山前农业区HNO_(3)扰动碳酸盐岩风化过程加速了22.80%±6.80%的Ca~(^(2+))和Mg~(^(2+))及18.10%±7.50%的HCO_(3)~-的释放。同时,相对碳酸盐岩自然风化,这一扰动过程降低了22.80%±6.80%的CO_(2)吸收量,并可能导致水质硬化程度加剧及NO_(3)~–污染风险增加。Carbonate rocks represent the largest carbon reservoir on Earth.A quantitative evaluation of the effects of HNO3 on the car⁃bonate weathering in the agricultural piedmont region is crucial for understanding the global carbon cycle.In July 2022,samples were collected from 13 monitoring points in the Qingshui River agricultural piedmont region.Hydrochemical and isotopic indicators(δ2H-H2 O、δ18O-H2 O、δ15N-NO_(3)^(-)andδ18O-NO_(3)^(-))were analyzed.The MixSIAR model was employed to identify the primary sources of NO_(3)^(-)in river water,while hydrogeochemical evidence was utilized to elucidate the key biogeochemical processes controlling NO_(3)^(-)lev⁃els.The results indicated that the water in this agricultural piedmont region of the upper reaches of the Qingshui River was typically weakly alkaline,with a chemical composition categorized as HCO3-Ca·Mg type,and the ion composition of the water was primarily influenced by the combined dissolution of calcite and dolomite.The MixSIAR model results revealed that the contribution ratios of pollution sources were as follows:atmospheric deposition(0.18%±0.06%)<NO_(3)^(-)-synthetic fertilizer(0.40%±0.11%)<soil organic nitrogen(9.30%±4.50%)<NH4+-synthetic fertilizer(16.10%±9.00%)<manure&domestic sewage(74.00%±13.00%).Approxi⁃mately 99.4%of riverine NO_(3)^(-)contents were derived from NH4+-containing pollutants.The HNO3 from microbial nitrification was in⁃volved in the weathering process of carbonate rocks.The participation of HNO3 in agricultural piedmont region accounted for 22.80%±6.80%of Ca^(2+)+Mg^(2+)and 18.10%±7.50%of HCO3–in the river water,while reducing the carbon sink flux of carbonate weathering by 22.80%±6.80%.This may potentially exacerbate the water hardness and increase the NO_(3)^(-)pollution risk.

关 键 词：山前农业区 硝酸盐 硝酸 碳酸盐岩风化 碳汇 

分 类 号：X522[环境科学与工程—环境工程]