长江流域难降解溶解态有机碳的入河量与断面输送通量及源贡献分析  

The basin loads of refractory dissolved organic carbon into river and source contribution of riverine flux in the key stations in the Changjiang River

作　　者：田思雨 王芳[1] 张培培 晏维金[1] 余其彪 储昭升[4] TIAN Siyu;WANG Fang;ZHANG Peipei;YAN Weijin;YU Qibiao;CHU Zhaosheng(Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101;University of Chinese Academy of Sciences,Beijing 100049;Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies,College of the Environment and Ecology,Xiamen University,Xiamen 361102;National Engineering Laboratory for Lake Pollution Control and Ecological Restoration,Chinese Research Academy of Environmental Sciences,Beijing 100012)

机构地区：[1]中国科学院地理科学与资源研究所,北京100101 [2]中国科学院大学,北京100049 [3]厦门大学环境与生态学院,福建省海陆界面生态环境重点实验室,厦门361102 [4]中国环境科学研究院,湖泊水污染治理与生态修复技术国家工程实验室,北京100012

出　　处：《环境科学学报》2023年第9期418-429,共12页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.42077304,41877483,42106214)。

摘　　要：河流溶解态有机碳(DOC)的迁移转化对流域尺度碳循环与碳的源汇机制具有重要意义.河流系统DOC中有相当一部分的难降解溶解态有机碳(Refractory Dissolved Organic Carbon,RDOC)在迁移转化过程中较难去除,是一个重要的碳库,但其结构和来源及其相对贡献和对碳排放的意义仍不清晰.本研究基于2017-2018年长江干、支流关键断面(30个站点)的逐月水文、水化学参数,包括直门达站、寸滩站和大通站的傅立叶变换离子回旋共振质谱(FT-ICR MS)分析的水质参数等,分析了长江关键断面RDOC浓度、单位面积输出量和输出通量,自上游至下游RDOC的结构组成变化,以及长江水系RDOC的不同来源及其相对贡献.结果表明:(1)长江流域2017-2018年两年平均RDOC输出通量为4.62×10^(8)kg·a^(-1),输出模数为270.7 kg·km^(-2)·a^(-1);表征RDOC的主要组分“稳定岛分子”的相对丰度从长江上游(直门达和寸滩站)到下游大通站呈增加趋势,稠环芳烃和多酚类的相对丰度也有类似的变化趋势.(2)长江水系RDOC的浓度、输出模数及通量存在显著的空间变化,在干流基本呈显著增加趋势.长江RDOC的源贡献有显著的空间差异,面源RDOC的占比自直门达站的96%下降到大通站55%,相反点源RDOC的占比从0增加到45%.汉江对长江RDOC输出通量的贡献最大,贡献率为36.54%,乌江流域贡献最小,贡献比只有1.17%.(3)COD_(Mn)/DO随着RDOC浓度的增加而增加,表明以COD表征的水体可降解DOC可能高估了,相应的DOC转化所产生的碳排放也被高估了.长江RDOC的输出通量占长江入河DOC通量的13%,占大通站输出DOC通量的30%.本研究建议,忽略RDOC的输送通量,将会高估DOC转化所产生的碳排放,数值约为2.61×10^(8)kg·a^(-1).The transportation and transformation of dissolved organic carbon(DOC)in streams and rivers plays important role in carbon cycle and carbon source-sink mechanisms at basin-scale.A fraction of DOC in river system is the refractory dissolved organic carbon(RDOC),which is difficult to remove during its transportation and constitutes one kind of carbon sink.However,the structure,sources and relative contribution,and implications to carbon emission of this fraction of DOC remain unclear.The RDOC concentration,yield and export flux,the RDOC sources and their relative contributions in stations of the Changjiang River,were studied based on the monthly hydrological and hydro-chemical parameters of thirty stations of the Changjiang River from 2017 to 2018.In addition,the RDOC molecular composition was also analyzed by using Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry at three mainstem stations.The results showed that the annual yield and export amount of RDOC were 270.7 kg·km^(-2) and 4.62×10^(8) kg C,respectively,in the Changjiang River.The relative abundance of molecular markers of RDOC,including moleculae with“Islands of Stability”,condensed aromatics and polyphenols,increased from the upper river to the lower river.The analysis of the source contribution of RDOC demonstrated that the proportion of RDOC from non-point source decreased from 96%in the Zhimenda station to 55%in the Datong station,in contrast,the proportion of RDOC from point source increased from 0 to 45%between the Zhimenda and the Datong station.The spatial patterns in concentration,yield and flux of RDOC varied significantly:the concentration and yield of RDOC showed a significant tendency from the upper river to the lower river along the mainstem.Furthermore,we found that the Hanjiang River branch contributed the highest ratio of the river export of RDOC,accounting for 36.54%;while the Wujiang River contributed the least,at a ratio of 1.17%.Our study found that COD_(Mn)/DO increase with increasing RDOC concentration,indicating tha

关 键 词：长江 难降解溶解性有机碳(RDOC) 分子组成 源贡献分析 碳排放 

分 类 号：X83[环境科学与工程—环境工程]