三峡库区表层沉积物有机碳、氮同位素特征及对有机质来源的指示  

Characteristics of organic carbon and nitrogen isotopes in surface sediment of Three Gorges Reservoir region and their implications for sources of organic matter

作　　者：茅昌平[1] 肖衡 王帅 贾志敏 王耀 饶文波[1] MAO Changping;XIAO Heng;WANG Shuai;JIA Zhimin;WAN Yao;RAO Wenbo(School of Earth Sciences and Engineering,Hohai University,Nanjing 211100,China;Yellow River Ecological and Environmental Science Research Institute,Zhengzhou 450003,China)

机构地区：[1]河海大学地球科学与工程学院,江苏南京211100 [2]黄河生态环境科学研究所,河南郑州450003

出　　处：《水资源保护》2023年第6期160-168,194,共10页Water Resources Protection

基　　金：江苏省自然科学基金项目(BK20191304);科技部重点研发项目(2016YFC0401703)。

摘　　要：为了阐明三峡库区表层沉积物有机质来源及其季节变化,基于2017年测定的三峡库区夏季和冬季干、支流表层沉积物样品中总有机碳(TOC)和总氮(TN)质量分数以及δ^(13)C_(org)和δ^(15)N,根据δ^(13)C_(org)和碳氮比确定了有机质来源范围,并运用δ^(15)N进行辅助分析,利用贝叶斯混合模型量化了三峡库区内有机质不同来源的贡献。结果表明:三峡库区表层沉积物中TOC和TN质量分数分别为0.79%~1.46%和0.07%~0.13%,夏季TOC质量分数略低于冬季,TN质量分数无季节差异;δ^(13)C_(org)和δ^(15)N值的范围分别为-26.35‰~-24.70‰和2.59‰~5.67‰,无季节差异;三峡库区表层沉积物有机质夏季主要来自土壤有机质和河流浮游生物,冬季以土壤有机质和水生维管束植物为主;两个季节污水有机质来源占比均处于第4位,三峡库区存在明显外源污染,主要与人工氮肥和生活污水有关,不存在明显季节变化。In order to clarify the sources and their seasonal variations of organic matter in surface sediment in the Three Gorges Reservoir region,the mass fractions of total organic carbon(TOC)and total nitrogen(TN)and theirδ^(13)C_(org)andδ^(15)N isotopes in surface sediment samples from the mainstream and tributaries of the Three Gorges Reservoir region were measured in the summer and winter of 2017.The source ranges of organic matter were determined according toδ^(13)C_(org)and the C/N ratio,withδ^(15)N used for auxiliary analysis,and the Bayesian mixed model was used to quantify the contributions of different sources of organic matter in the Three Gorges Reservoir region.The results showed that the mass fractions of TOC and TN in surface sediment of the Three Gorges Reservoir region were 0.79%to 1.46%and 0.07%to 0.13%,respectively.The mass fraction of TOC in summer is slightly lower than that in winter,and that of TN has no seasonal difference.The ranges ofδ^(13)C_(org)andδ^(15)N were-26.35‰to-24.70‰and 2.59‰to 5.67‰,respectively,without seasonal difference.The organic matter of surface sediment in the Three Gorges Reservoir region mainly comes from soil organic matter and river plankton in summer,and soil organic matter and aquatic vascular plants dominate in winter.The proportion of sewage organic matter takes the fourth place in summer and winter,and further analysis withδ^(15)N reveals that there is obvious external pollution in the Three Gorges Reservoir region,which is mainly related to artificial nitrogen fertilizer and domestic sewage,without obvious seasonal variation.

关 键 词：表层沉积物 碳同位素 氮同位素 有机质 三峡库区 

分 类 号：X142[环境科学与工程—环境科学] X524