沅江入湖段河床沉积物重金属污染源的铅同位素示踪  

Lead isotopic tracing on source of heavy metal contamination in sediments from the Yuanjiang River inlet to Dongting Lake,China

作　　者：江春霞 彭渤[1,2] 方小红 李晓敏 邬思成 谢淑容[4] 吴晶 郭馨彤 陈海生 戴亚南 JIANG Chunxia;PENG Bo;FANG Xiaohong;LI Xiaomin;WU Sicheng;XIE Shurong;WU Jing;GUO Xintong;CHEN Haisheng;DAI Yanan(College of Geographical Sciences,Hunan Normal University,Changsha 410081;Key Laboratory of Environmental Heavy-Metal Contamination and Ecological Remediation,Hunan Normal University,Changsha 410081;College of Geography and Tourism,Hengyang Normal University,Hengyang 421000;School of Earth Sciences,East China University of Technology,Nanchang 330013)

机构地区：[1]湖南师范大学,地理科学学院,长沙410081 [2]湖南师范大学,环境重金属污染机理与生态修复重点实验室,长沙410081 [3]衡阳师范学院,地理与旅游学院,衡阳421000 [4]东华理工大学,地球科学学院,南昌330013

出　　处：《环境科学学报》2022年第4期225-236,共12页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.41073095);湖南省一流学科(地理学)建设项目;湖南省高校科技创新团队支持计划项目(2014)。

摘　　要：利用多接收等离子质谱仪(MC-ICP-MS)对沅江入湖段河床沉积物重金属含量与铅同位素进行分析,评价了重金属富集程度,并示踪分析重金属污染源.结果表明,上层(0~52 cm)沉积物明显富集Bi、Cd、Cr、Mn、Ni、Cu、Zn、Pb等多种重金属,中层(52~172 cm)、下层(172~268 cm)沉积物中Mn、Cd富集明显.垂直方向上,重金属的富集具有自下而上富集程度明显增强、富集的元素种类明显增多的变化特征,暗示近年来人为活动增强引起沉积物污染程度增强.沉积物铅同位素比值变化范围大,其^(206)Pb/^(207)Pb、^(208)Pb/^(207)Pb比值变化范围依次为1.1310~1.2040、2.3321~2.4932,并以相对富放射成因的U铅和Th铅为特征.上层沉积物铅同位素比值变化大,且自下而上升高或降低的变化明显,沉积物铅含量高对应^(206)Pb/^(207)Pb比值低,铅含量低则对应^(206)Pb/^(207)Pb比值高;中层、下层沉积物铅同位素比值变化小,且中层、下层沉积物铅含量高低与^(206)Pb/^(207)Pb比值高低无明显对应变化关系.铅同位素示踪分析表明,沉积物中的铅来源主要包括燃煤、柴油、铅锌矿矿石等人为源铅,以及来自板溪群板岩、下寒武统黑色页岩等自然源铅.沉积物存在Bi、Cd、Mn、Cu、Zn、Ba、Pb等重金属的复合污染,且这些重金属与Pb有相似的来源,既有燃煤、柴油和铅锌矿矿石等人为源的贡献,又有黑色页岩、板岩等自然源的影响.The concentrations of heavy metals and lead isotope ratios in sediments from the Yuanjiang River inlet to Dongting Lake were systematically analyzed using MC-ICP-MS techniques.Then,the enrichment degree of heavy metals was evaluated,and the source of heavy metal contamination in sediments was traced by using Pb isotopes.The results show that sediments in upper layer(from 0 to 52 cm in depth)of the sediment core were highly enriched in heavy metals Bi,Cd,Cr,Mn,Ni,Cu,Zn and Pb(1.5<EF<3.0),while these in middle(52 to 172 cm)and lower layer(from 172 to 268 cm)were significantly enriched in Mn and Cd.The degree of heavy-metal enrichment and the number of enriched heavy metals in sediments increases vertically upward the sediment core.This indicates that heavy metal contamination in sediments was related to human activities that increased input of heavy metals in sediments in recent years.Lead isotope ratios varied in wider ranges,with ^(206)Pb/^(207)Pb and ^(208)Pb/^(207)Pb ratios ranging from 1.1310 to 1.2040 and 2.3321 to 2.4932 respectively.Pb isotope composition of sediments was characterized by enrichment of Pb from decay both Th(Th-Pb)and U(U-Pb).Pb isotope ratios in upper layer sediments varied in a wider range,which increased or decreased significantly upward the sediment core,for which sediments with higher Pb concentration have lower ^(206)Pb/^(207)Pb ratio,and vice versa.While,Pb isotope ratios in middle and lower layers of sediments varied in minor variation,and the above relationship between Pb concentrations and ^(206)Pb/^(207)Pb ratios were not observed.The lead isotopic tracing suggested that Pb in sediments may be contributed from the anthropogenic sources including coal combustion,use of diesel,and mining for Pb-Zn ores,and from lithological sources such as black shale and slate through weathering and erosion.As heavy metal Bi,Cd,Mn,Cu,Ba and Zn behaved very similarly with lead,it was then suggested that contamination of these heavy metals(Bi,Cd,Mn,Cu,Ba,and Zn)in sediments was resulted from the mixi

关 键 词：铅同位素 人为源铅 自然源铅 重金属污染 沉积物 沅江 

分 类 号：X142[环境科学与工程—环境科学]