人为活动对乌江中上游段岩溶地下水δ13CDIC及碳汇效应的影响  

THE IMPACT OF HUMAN ACTIVITIES TO δ13CDIC OF KARST GROUNDWATER AND CARBON SINK IN THE UPPER AND MIDDLE REACHES OF WUJIANG RIVER

作　　者：黄奇波[1] 覃小群[1] 刘朋雨[1] 张连凯[1] 苏春田[2] 

机构地区：[1]中国地质科学院岩溶地质研究所,桂林541004 [2]国土资源部/广西壮族自治区岩溶动力学重点实验室,桂林541004

出　　处：《第四纪研究》2016年第6期1358-1369,共12页Quaternary Sciences

基　　金：中国地质调查局地质调查项目（批准号：12120113005200）和国家自然科学基金项目（批准号：41302211）共同资助

摘　　要：定量评价人为活动对岩溶碳汇效应的影响有助于提高岩石风化碳汇通量估算精度，对当前全球气候变化研究意义重大。本文选取乌江中上游段岩溶区为研究对象，在雨季和旱季对研究区68个岩溶地下水（雨季42个，旱季26个）的水化学、溶解无机碳（DIC）同位素组成（δ13CDIC）进行了测试，利用化学计量法计算了H2SO4和HNO3对流域岩溶碳汇效应的影响程度。结果表明：1）雨季和旱季岩溶地下水中阴离子均以HCO3-和SO42-为主，两者占总阴离子的85%以上；阳离子以Ca2＋和Mg2＋为主，两者占总阳离子的55%以上。Ca2＋＋Mg2＋相对于HCO3-过量，过量的Ca2＋＋Mg2＋与SO42-＋NO3-相平衡。2）雨季和旱季岩溶地下水的δ13CDIC值分别介于-14.19‰^-8.27‰和-12.98‰^-9.09‰之间。总体上，雨季的δ13CDIC更为偏负，且变化范围较大，均与[SO42-＋NO3-]/[HCO3-]呈正相关性，证实H2SO4和HNO3参与了流域碳酸盐岩的溶蚀并使δ13CDIC值增加。3）由于H2SO4和HNO3参与，雨季碳酸盐岩溶蚀消耗的CO2（CO2ATM-SOIL）占水中HCO3-的比例（CO2ATM-SOIL/total HCO3-）平均值为33.83%，旱季平均值为35.84%，与H2CO3溶蚀碳酸盐岩的CO2ATM-SOIL/total HCO3-理论值（50%）相比，分别减少16.17%和14.16%。因此，雨季岩溶碳汇效应将减少32.34%，旱季将减少28.32%。Quantitative evaluation of the impact of human activities to karst carbon sink not only helps to improve the estimation accuracy of karst carbon sinks,but also is significant for the current research on global climate change.The Wujiang River,the largest river in Guizhou Province,is a tributary of the Yangtze River with a highest proportion of carbonate.Recently,with the fast population proliferation and rapid economic growth,the drainage basin is intensively interfered by anthropogenic activities and shows an increasing SO42- and NO3- concentration.For investigating the hydrochemical characteristics and the main influencing factors,the hydrochemistry and Carbon isotope in dissolved inorganic carbon （DIC） from 42 and 26 karst groundwater samples were sampled and analyzed during the rainy （July,2013） and dry （October,2013） seasons,respectively,from the Upper and Middle reaches of Wujiang River.The contribution of atmospheric/soil CO2（CO2ATM-SOIL） to the total HCO3-（CO2ATM-SOIL/total HCO3-） were calculated using the stoichiometry method.The results showed that the advantage cations of groundwater and surface water were Ca2＋ and Mg2＋,which accounted for more than 55%,and the advantage anions were HCO3- and SO42-,accounting for more than 85%.The concentrations of Ca2＋ and Mg2＋ exceeded the equivalent concentrations of HCO3-,which the excess of Ca2＋ and Mg2＋ cations were compensated by SO42-＋NO3-.The δ13CDIC of karst groundwater in the rainy and dry seasons,ranged from -14.19‰ to -8.27‰ and from -12.98‰ to -9.09‰,respectively,with a more depleted value in rainy season.A good positive correlation between δ13CDIC value and [SO42-＋NO3-]/[HCO3-] indicated that sulphuric and nitric acid might play a relatively important role in carbonate weathering and has an important influence on δ13CDIC value.The average contribution of atmospheric/soil CO2（CO2ATM-SOIL） to the total HCO3-（CO2ATM-SOIL/total HCO3-） is 33.83% for rainy season,and 35.84% for post-rainy reason,which corr

关 键 词：岩溶碳汇 δ13CDIC H2SO4 HNO3 乌江中上游 

分 类 号：X143[环境科学与工程—环境科学] P641.3[天文地球—地质矿产勘探]