Chromophoric dissolved organic matter(CDOM)strongly influences the water-leaving radiance from aquatic ecosystems.In most inland waters,the remote determination of CDOM absorption presents a central challenge due to t...Chromophoric dissolved organic matter(CDOM)strongly influences the water-leaving radiance from aquatic ecosystems.In most inland waters,the remote determination of CDOM absorption presents a central challenge due to their complex optical conditions.However,identifying the temporal and spatial variability of CDOM is fundamental to the understanding of aquatic biogeo-chemical dynamics.In the present study,semi-analytical and empirical modeling approaches were used to examine CDOM absorption in four,shallow,inland water bodies using the spectral bands and sensitivities of major satellite observational systems.Of the models examined,an empirical multiband model was found to provide the highest correlation with measured CDOM absorption.The spectral characteristics of the MERIS sensors yielded the best results with respect to the other available satellite sensors.High detrital load was observed to be a major impediment to estimating CDOM absorption,while lakes with elevated phytoplankton biomass did not present similar problems.展开更多
Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-exp...Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-explanatory. Organic geochemistry studies of lake sediments from Qinghai Lake have been investigated, but some interpretations are controversial. In this study, TOC of one Holocene eolian section and δ（13）C（org） of three eolian sections were studied around Qinghai Lake. Results indicate that the TOC content in eolian deposits was low during the Early Holocene, and gradually increased to high values during the Middle and Late Holocene. The variation in TOC content of eolian deposits is different from that in the lacustrine sequence from Qinghai Lake during the Holocene. The δ（13）C（org） values in the eolian sections were relatively stable, with oscillation amplitudes of 4‰（ranging from-25.8‰ to-22.1‰）, in contrast to 10‰ variation s in δ（13）C（org） values（varying from-30‰ to-20‰） in lacustrine sediments. Through comparison of TOC and δ（13）C（org） values between eolian deposits and lacustrine sediments, we can confirm indications that the organic matter in Qinghai Lake sediments during the Holocene was primarily a contribution of the aquatic species in the lake. This is significant for understanding the origin of organic matter in lake sediments on the northeastern Qinghai-Tibetan Plateau and for paleoenvironmental inferences using such proxies.展开更多
基金We gratefully acknowledge the financial support of the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX2-YW-QN311,No.KZCX2-EW-QN308)National Natural Science Foundation of China(Grant No.40871168,No.40801137)the Dragon 3 Projects(ID-10561).
文摘Chromophoric dissolved organic matter(CDOM)strongly influences the water-leaving radiance from aquatic ecosystems.In most inland waters,the remote determination of CDOM absorption presents a central challenge due to their complex optical conditions.However,identifying the temporal and spatial variability of CDOM is fundamental to the understanding of aquatic biogeo-chemical dynamics.In the present study,semi-analytical and empirical modeling approaches were used to examine CDOM absorption in four,shallow,inland water bodies using the spectral bands and sensitivities of major satellite observational systems.Of the models examined,an empirical multiband model was found to provide the highest correlation with measured CDOM absorption.The spectral characteristics of the MERIS sensors yielded the best results with respect to the other available satellite sensors.High detrital load was observed to be a major impediment to estimating CDOM absorption,while lakes with elevated phytoplankton biomass did not present similar problems.
基金funded by Chinese Post-doctoral Research Fund (No. 2014T70951)the National Natural Science Foundation of China (Nos. 41201014, 41371028, 41402314)
文摘Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-explanatory. Organic geochemistry studies of lake sediments from Qinghai Lake have been investigated, but some interpretations are controversial. In this study, TOC of one Holocene eolian section and δ（13）C（org） of three eolian sections were studied around Qinghai Lake. Results indicate that the TOC content in eolian deposits was low during the Early Holocene, and gradually increased to high values during the Middle and Late Holocene. The variation in TOC content of eolian deposits is different from that in the lacustrine sequence from Qinghai Lake during the Holocene. The δ（13）C（org） values in the eolian sections were relatively stable, with oscillation amplitudes of 4‰（ranging from-25.8‰ to-22.1‰）, in contrast to 10‰ variation s in δ（13）C（org） values（varying from-30‰ to-20‰） in lacustrine sediments. Through comparison of TOC and δ（13）C（org） values between eolian deposits and lacustrine sediments, we can confirm indications that the organic matter in Qinghai Lake sediments during the Holocene was primarily a contribution of the aquatic species in the lake. This is significant for understanding the origin of organic matter in lake sediments on the northeastern Qinghai-Tibetan Plateau and for paleoenvironmental inferences using such proxies.
