溶解性有机质（DOM）是湖泊生态系统重要组成部分,其性质和结构决定了其在污染物（例如汞）环境行为中扮演着重要角色。本研究选取三峡库区内陆腹地典型水库型湖泊———长寿湖,采用吸收光谱表征方法,通过1年时间对 DOM 地球化学变化规...溶解性有机质（DOM）是湖泊生态系统重要组成部分,其性质和结构决定了其在污染物（例如汞）环境行为中扮演着重要角色。本研究选取三峡库区内陆腹地典型水库型湖泊———长寿湖,采用吸收光谱表征方法,通过1年时间对 DOM 地球化学变化规律进行了定性定量分析,并结合汞观测数据,讨论了 DOM 对不同形态汞浓度的影响。结果表明,和1月相比,长寿湖4～11月 DOC 差异性低于 CDOM,4～11月间差异性不显著。有色组分变化是解释 DOM 季节性变化的重要原因。 DOM 中主要生色团仍然来自于大分子量的芳香性组分。而 CDOM 三波长模型可较好对 DOC 的年际观测进行反演。同时,SUVA254和S 275～295季节性变化特征较明显,1月芳香性和分子量均最小,4月上升。与其他类型湖泊相比,长寿湖水体 DOM 芳香性和分子量大小均低于森林湖泊,但高于高原湖泊。周边生态系统和土地利用类型对湖泊 DOM 差异影响明显。另外,SUVA254和 DOC与各形态 Hg 无明显相关性,但水体生色组分和分子量大小是控制溶解态和活性汞的重要因素；而湖区甲基汞变化可能与湖泊初级生产力导致的有机质富集和迁移关系密切。展开更多
Based on the detailed analyses,multi-proxies such as AMS 14 C dating,grain size,component and morphology of heavy minerals,micromorphology of zircon,magnetic susceptibility,Rb/Sr and Hg content are used to research th...Based on the detailed analyses,multi-proxies such as AMS 14 C dating,grain size,component and morphology of heavy minerals,micromorphology of zircon,magnetic susceptibility,Rb/Sr and Hg content are used to research the paleoflood sediments archived in the Yuxi Site.The research indicates that, since 7.6 kaBP,at least 16 times of paleoflood with water level above Wusong Elevation 147.024 m(a.s.l.) left deposits in the Neolithic layers of unit T0403 from the Yuxi Site.The results are induced from the following aspects:(1)The plaeoflood sediments take on great similarities with modern flood sediments in the Yuxi Site and Zhongba Site in probability cumulative curves which mainly show a pattern of 3 segments in fluvial pattern.(2)There is some resemblance between the heavy mineral components and the zircon shape characteristics of paleoflood deposits and those of modern flood deposits.(3) Magnetic susceptibility values(40.44―70.10SI)are lower than those of sediments from cultural layers (59.59―188.68SI).(4)Hg values(290.71―742.51 ng/g)are lower than those of sediments from cultural layers(344.16―10518.17 ng/g).(5)Rb/Sr values are higher than those of sediments from cultural layers, while those of the 4th,5th,6th,7th,8th cultural layers are high,which shows that they are inundated by paleoflood.The reason for many flood deposits existing is related to the site situated on the first terrace where the Yuxi River joins with the Yangtze River.As there are some similarities between the plaeoflood sediments and those of the Zhongba Site,it is feasible to confirm the existence of paleoflood sediments based on the above points.展开更多
文摘溶解性有机质（DOM）是湖泊生态系统重要组成部分,其性质和结构决定了其在污染物（例如汞）环境行为中扮演着重要角色。本研究选取三峡库区内陆腹地典型水库型湖泊———长寿湖,采用吸收光谱表征方法,通过1年时间对 DOM 地球化学变化规律进行了定性定量分析,并结合汞观测数据,讨论了 DOM 对不同形态汞浓度的影响。结果表明,和1月相比,长寿湖4～11月 DOC 差异性低于 CDOM,4～11月间差异性不显著。有色组分变化是解释 DOM 季节性变化的重要原因。 DOM 中主要生色团仍然来自于大分子量的芳香性组分。而 CDOM 三波长模型可较好对 DOC 的年际观测进行反演。同时,SUVA254和S 275～295季节性变化特征较明显,1月芳香性和分子量均最小,4月上升。与其他类型湖泊相比,长寿湖水体 DOM 芳香性和分子量大小均低于森林湖泊,但高于高原湖泊。周边生态系统和土地利用类型对湖泊 DOM 差异影响明显。另外,SUVA254和 DOC与各形态 Hg 无明显相关性,但水体生色组分和分子量大小是控制溶解态和活性汞的重要因素；而湖区甲基汞变化可能与湖泊初级生产力导致的有机质富集和迁移关系密切。
基金Supported by the National Natural Science Foundation of China(Grant No.90411015)the National Science and Technology Support Project(Grant No.2006BAK21B02)+3 种基金the University Doctoral Foundation(Grant No.20050284011)the Foundation of Important Basic Research at Nanjing University(Grant No.0209005206)the Open Foundation of the State Key Laboratory of Loess and Qua-ternary Geology from the Institute of Earth Environment,CAS(Grant No.SKLLQG0503)the Physical Geography of"985"Items and the Test Foundation of Modern Analyses Center of Nanjing University(Grant No.0209001309)
文摘Based on the detailed analyses,multi-proxies such as AMS 14 C dating,grain size,component and morphology of heavy minerals,micromorphology of zircon,magnetic susceptibility,Rb/Sr and Hg content are used to research the paleoflood sediments archived in the Yuxi Site.The research indicates that, since 7.6 kaBP,at least 16 times of paleoflood with water level above Wusong Elevation 147.024 m(a.s.l.) left deposits in the Neolithic layers of unit T0403 from the Yuxi Site.The results are induced from the following aspects:(1)The plaeoflood sediments take on great similarities with modern flood sediments in the Yuxi Site and Zhongba Site in probability cumulative curves which mainly show a pattern of 3 segments in fluvial pattern.(2)There is some resemblance between the heavy mineral components and the zircon shape characteristics of paleoflood deposits and those of modern flood deposits.(3) Magnetic susceptibility values(40.44―70.10SI)are lower than those of sediments from cultural layers (59.59―188.68SI).(4)Hg values(290.71―742.51 ng/g)are lower than those of sediments from cultural layers(344.16―10518.17 ng/g).(5)Rb/Sr values are higher than those of sediments from cultural layers, while those of the 4th,5th,6th,7th,8th cultural layers are high,which shows that they are inundated by paleoflood.The reason for many flood deposits existing is related to the site situated on the first terrace where the Yuxi River joins with the Yangtze River.As there are some similarities between the plaeoflood sediments and those of the Zhongba Site,it is feasible to confirm the existence of paleoflood sediments based on the above points.
