河-库连续体中溶解性无机碳及其同位素的时空分异特征——以澜沧江云南段为例  

Spatio-temporal variations of dissolved inorganic carbon and its isotopes in river-reservoir continuum: A case study on Yunnan Section of the Lancang River

作　　者：袁博[1] 吴巍[1] 郭梦京[1] 周孝德[1] 谢曙光[2] YUAN Bo;WU Wei;GUO Mengjing;ZHOU Xiaode;XIE Shuguang(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi'an University of Technology,Xi'an 710048,P.R.China;College of Environmental Science and Engineering,Peking University,Beijing 100871,P.R.China)

机构地区：[1]西安理工大学西北旱区生态水利国家重点实验室,西安710048 [2]北京大学环境科学与工程学院,北京100871

出　　处：《湖泊科学》2020年第1期173-186,共14页Journal of Lake Sciences

基　　金：国家自然科学基金项目(91747206)资助

摘　　要：河流及水库等水生态系统中的溶解性无机碳(DIC)是全球碳循环与大气、陆地和海洋之间碳相互作用的重要组成部分.以澜沧江云南段上游天然河段及下游梯级水库群形成的连续体为研究对象,分析了河库连续体表层水体中水化学特征、溶解性无机碳浓度及其碳同位素时空分布特征.研究结果表明:河库连续体水体中溶解无机碳(DIC)及其同位素(δ13 C DIC)组成特征总体表现为:DIC浓度丰水期较低,枯水期较高,平均值分别为2.59±0.44和3.30±0.37 mmol/L;δ13 C DIC值丰水期偏负、枯水期偏正,平均值分别为-8.52‰±0.38‰和-6.95‰±0.53‰,与自然河流的季节变化特征相似.水体DIC来源主要包括土壤及水体有机质分解生成的CO 2、碳酸盐风化和水气界面CO 2的交换过程.澜沧江河库连续体中DIC浓度及δ13 C DIC组成的时空异质性特征与流域岩性、土壤生物地球化学过程以及微生物活动强度等均有较大关系.当前,澜沧江梯级水库群建库时间短,梯级联合运行下调度复杂,水文条件多变,梯级水库对河流重要生源要素——碳累积影响方面的“水库效应”还不明显.Dissolved inorganic carbon(DIC)in river and reservoir aquatic ecosystems is an important component of global carbon cycle and the interaction among atmospheric,terrestrial and marine carbon.The hydrochemical characteristics,dissolved inorganic carbon concentration,and spatial and temporal distribution characteristics ofδ13 C DIC in the surface water of the natural reach and cascade reservoirs in Yunnan Section of the Lancang River were analyzed.The results show that the composition of DIC andδ13 C DIC in the river-reservoir continuum was generally characterized by lower DIC concentration in wet season and higher in dry season,with the mean values of 2.59±0.44 and 3.30±0.37 mmol/L,respectively and negative value ofδ13 C DIC in wet season and positive in dry season,with the mean values of-8.52‰±0.38‰and-6.95‰±0.53‰,respectively.The changing characteristics in the Lancang River were similar with the natural rivers.The sources of DIC in water body mainly include CO 2 generated by decomposition of organic matter in soil and water body,weathering of carbonate and CO 2 exchange at water-atmosphere interface.The temporal and spatial heterogeneity of DIC concentration and the composition ofδ13 C DIC in river-reservoir continuum is closely related to the lithology of river basin,soil biogeochemical process and microbial activity.At present,the Lancang River cascade reservoirs are short in construction age,complex in operation and changeable in hydrological conditions.The‘hydrological effect of reservoir’of cascade reservoirs on the accumulation of carbon,the important biogenic elements,is not obvious.

关 键 词：澜沧江 溶解性无机碳 δ13 C DIC 梯级水库 河库连续体 

分 类 号：X52[环境科学与工程—环境工程]