To better understand the Fe isotope characteristics of natural samples in the Karst area,the Fe isotope compositions of riverine suspended particulates,lake suspended particulates,lake sediments,porewaters,phytoplankt...To better understand the Fe isotope characteristics of natural samples in the Karst area,the Fe isotope compositions of riverine suspended particulates,lake suspended particulates,lake sediments,porewaters,phytoplanktons,and aerosols in the watersheds of Lake Aha（a mineralized water system）and Lake Hongfeng（a mesotrophic water system）,which are located in the Karst area, southwest China,were investigated.The studied samples displayed a variable range betweenδ^（56）Fe=-2.03‰and 0.36‰.Aerosols and phytoplanktons have similar or slightly heavier Fe isotope compositions relative to the average of igneous rocks.Fe isotope compositions of riverine Suspended Particulate Matter（SPM）were mainly affected by the types of tributaries.Suspended particulates collected from tributaries seriously contaminated with coal mine drainages displayed negativeδ^（56）Fe values（-0.89‰to-0.31‰）during summer,and there were significant increases ofδ^（56）Fe values in winter,except AR2,which was polluted with both coal mine drainage and sewage effluent. Characteristics of lakes have important influences on Fe isotope compositions of suspended particulates,lake sediments,and porewaters.The epilimnetic particulate Fe of Lake Hongfeng hadδ^（56）Fe=-0.04‰to 0.13‰,while lighter Fe isotope compositions were measured for particulate Fe from Lake Aha,ranging from-0.42‰to-0.09‰.Sediments collected from Hou Wu（HW）station of Lake Hongfeng have an averageδ^（56）Fe value of 0.09‰and their corresponding porewaters have lighter Fe isotope compositions,ranging from-0.57‰to-0.31‰;no significant variations have been observed. For the Liang Jiang Kou（LJK）station of Lake Aha,the content of reactive Fe and the concentration of sulfate were all high.Due to the reactive Fe recycling,including dissimilatory Fe reduction,adsorption, and Fe-sulfide formation,porewaters sampled near the sediment surface have been found to have aδ^（56）Fe value as low as-2.03‰and an increase up to 0.12‰,with a burial depth of 10 cm.In contrast,an opposite variation trend was found for LJK sediments.Sediments sampled at 1-cm depth had a value ofδ^（56）Fe=-0.59‰and decrease as low as-1.75‰with burial depth.This investigation demonstrated that significant Fe isotope fractionations occur in surface environments.Fe isotope compositions of particulate Fe were seriously affected by Fe sources,and Fe biogeochemical recycling has an important influence on Fe isotope fractionations in lake sediments,especially when there are significant amounts of reactive Fe and sulfate.展开更多
Jiuzhaigou Conservation is a typical karst region with scenic tufa constructive landscape. With observation in situ and optical microscope as well as scanning electronic microscope, a series minor and micro biokar...Jiuzhaigou Conservation is a typical karst region with scenic tufa constructive landscape. With observation in situ and optical microscope as well as scanning electronic microscope, a series minor and micro biokarst solution features and related agents were identified and described related to local environmental condition, and also the bioeffect on karst deposition in formation of the local tufa dammed lakes were elucidated and discussed.It is shown in the cycle model proposed in the paper that many organisms (algae,mosses,and bushes etc.) with various effects (assimilation,interception,encrustation,trapping and binding etc.)on tufa deposition play an important role throughout the compound cycle process of the tufa dam gradation,i.e.the formation of the tufa dammed lakes in the stream channels which are character of local karst landscape.展开更多
基金supported by the Natural Science Foundation of China(no40903008,90610037, 40721002,and 40331005)the Open Research Fund of State Key Laboratory of Environmental Geochemistry, Chinese Academy of Sciences(SKLEG9006)the Chinese important special project(No2009ZX07419-003)
文摘To better understand the Fe isotope characteristics of natural samples in the Karst area,the Fe isotope compositions of riverine suspended particulates,lake suspended particulates,lake sediments,porewaters,phytoplanktons,and aerosols in the watersheds of Lake Aha（a mineralized water system）and Lake Hongfeng（a mesotrophic water system）,which are located in the Karst area, southwest China,were investigated.The studied samples displayed a variable range betweenδ^（56）Fe=-2.03‰and 0.36‰.Aerosols and phytoplanktons have similar or slightly heavier Fe isotope compositions relative to the average of igneous rocks.Fe isotope compositions of riverine Suspended Particulate Matter（SPM）were mainly affected by the types of tributaries.Suspended particulates collected from tributaries seriously contaminated with coal mine drainages displayed negativeδ^（56）Fe values（-0.89‰to-0.31‰）during summer,and there were significant increases ofδ^（56）Fe values in winter,except AR2,which was polluted with both coal mine drainage and sewage effluent. Characteristics of lakes have important influences on Fe isotope compositions of suspended particulates,lake sediments,and porewaters.The epilimnetic particulate Fe of Lake Hongfeng hadδ^（56）Fe=-0.04‰to 0.13‰,while lighter Fe isotope compositions were measured for particulate Fe from Lake Aha,ranging from-0.42‰to-0.09‰.Sediments collected from Hou Wu（HW）station of Lake Hongfeng have an averageδ^（56）Fe value of 0.09‰and their corresponding porewaters have lighter Fe isotope compositions,ranging from-0.57‰to-0.31‰;no significant variations have been observed. For the Liang Jiang Kou（LJK）station of Lake Aha,the content of reactive Fe and the concentration of sulfate were all high.Due to the reactive Fe recycling,including dissimilatory Fe reduction,adsorption, and Fe-sulfide formation,porewaters sampled near the sediment surface have been found to have aδ^（56）Fe value as low as-2.03‰and an increase up to 0.12‰,with a burial depth of 10 cm.In contrast,an opposite variation trend was found for LJK sediments.Sediments sampled at 1-cm depth had a value ofδ^（56）Fe=-0.59‰and decrease as low as-1.75‰with burial depth.This investigation demonstrated that significant Fe isotope fractionations occur in surface environments.Fe isotope compositions of particulate Fe were seriously affected by Fe sources,and Fe biogeochemical recycling has an important influence on Fe isotope fractionations in lake sediments,especially when there are significant amounts of reactive Fe and sulfate.
文摘Jiuzhaigou Conservation is a typical karst region with scenic tufa constructive landscape. With observation in situ and optical microscope as well as scanning electronic microscope, a series minor and micro biokarst solution features and related agents were identified and described related to local environmental condition, and also the bioeffect on karst deposition in formation of the local tufa dammed lakes were elucidated and discussed.It is shown in the cycle model proposed in the paper that many organisms (algae,mosses,and bushes etc.) with various effects (assimilation,interception,encrustation,trapping and binding etc.)on tufa deposition play an important role throughout the compound cycle process of the tufa dam gradation,i.e.the formation of the tufa dammed lakes in the stream channels which are character of local karst landscape.
