济南泉域岩溶水系统硝酸盐空间分布及溯源解析  

Spatial distribution and traceability analysis of nitrate in karst water system in Jinan spring basin

作　　者：王开然 陈华伟 吴振 仇钰婷 傅世东 WANG Kairan;CHEN Huawei;WU Zhen;QIU Yuting;FU Shidong(Water Resources Research Institute of Shandong Province,Jinan,250014,China;Shandong Provincial Key Laboratory of Water Resources and Environment,Jinan,250014,China)

机构地区：[1]山东省水利科学研究院,济南250014 [2]山东省水资源与水环境重点实验室,济南250014

出　　处：《环境化学》2024年第3期961-973,共13页Environmental Chemistry

基　　金：国家重点研发计划项目(2021YFC3200504);山东省自然科学基金(ZR2019QEE036);山东省水利科学研究院自选课题(SDSKYZX202119,SDSKYZX202121-2)资助。

摘　　要：人为活动产生的硝酸盐(NO_(3)^(-))污染是北方岩溶泉域面临的最普遍的环境问题之一.以济南泉域为研究对象,于2020年9月采集地下水和地表水样品共30件,综合利用水化学分析方法耦合硝酸盐氮氧同位素(δ^(15)NNO_(3)和δ^(18)ONO_(3))示踪技术,分析研究区NO_(3)^(-)来源及空间分布.结果表明,研究区主要阴、阳离子浓度从高到低依次为HCO_(3)->SO_(4)^(2-)>Cl^(-)>NO_(3)^(-)、Ca^(2+)>Na^(+)>Mg^(2+)>K+,水化学类型以HCO_(3)·SO_(4)-Ca为主.地下水NO_(3)^(-)浓度平均值(37.93 mg·L^(-1))高于地表水(10.15 mg·L^(-1)).有7个地下水采样点明显受到NO_(3)^(-)污染,超标率为27%,上游补给区及下游汇集排泄区采样点地下水NO_(3)^(-)浓度较高,而径流区采样点地下水NO_(3)^(-)浓度相对偏低.NO_(3)^(-)浓度主要受到无N形态转化的混合过程的影响,反硝化作用并不显著.δ^(15)N和δ^(18)O值范围分别为1.05‰-14.43‰和-7.92‰-22.94‰,MixSIAR模型计算结果显示,粪便和污水对地下水和地表水NO_(3)^(-)的贡献率最大,分别为39.9%和51.5%,其次为土壤氮及降雨和化肥中的NH4+,大气沉降的贡献率最低,说明粪便和污水是该区NO_(3)^(-)污染的主要来源,也可能有土壤有机氮和化肥的混合.Nitrate pollution caused by human activities is one of the most common environmental problems in karst spring areas in north China.A total of 30 groundwater and surface water samples were collected in Jinan Spring Basin in September 2020.The source and spatial distribution of nitrate pollution in the study area were analyzed by using hydrochemical analysis method coupled with nitrate nitrogen and oxygen double isotope tracer technology.The results show that the sequences of major anions and cations in water were HCO_(3)->SO_(4)^(2-)>Cl^(-)>NO_(3)^(-)and Ca^(2+)>Na^(+)>Mg^(2+)>K+,respectively.And the main water chemistry type was HCO_(3)·SO_(4)-Ca.The average NO_(3)^(-)concentration in groundwater(37.93 mg·L^(-1))was higher than that in surface water(10.15 mg·L^(-1)).Waters of 7 sampling sites were obviously polluted by nitrate,exceeding standard rate was 27%,and the concentration of NO_(3)^(-)-N in groundwater at the sampling points of upstream recharge area and downstream drainage area was higher than from runoff area.The concentration of NO_(3)^(-)was mainly affected by the mixing process,while no obvious denitrification occurred.The values ofδ^(15)ONO_(3)andδ^(18)ONO_(3)ranged from 1.05‰to 14.43‰and-7.92‰to 22.94‰,respectively.According to the calculation results of Bayesian isotope mixing model(MixSIAR),manure and sewage was mainly nitrate source of the groundwater and surface water,accounting for 39.3%and 52.3%of the total contribution,respectively.Soil nitrogen and NH4+in rainfall and fertilizer were the second,and the contribution rate of atmospheric deposition was the lowest.The results indicated that manure and sewage was the main source of nitrate pollution in this area,and there may be a mixture of soil organic nitrogen and chemical fertilizer.

关 键 词：岩溶水系统 水化学特征 硝酸盐 空间分布 污染溯源 

分 类 号：X52[环境科学与工程—环境工程]