XU Dan1,2, CHEN Jing-an1,*, YANG Hai-quan1,2, WANG Jing-fu1,2, JI Yong-xue1,2
(1.The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
2. University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract: Investigations on the dissolved organic carbon (DOC) and particulate organic carbon (POC) in lake water help to reveal the sources and fate of organic carbon. The concentrations and stable carbon isotopic compositions of dissolved organic carbon (DOC) and particulate organic carbon (POC) in Lake Baihua, Southwest China, were determined to investigate the spatial distribution of organic carbon in the stratified water column of Lake Baihua. The results indicated that DOC and POC concentrations are within the ranges of 1.97~3.26 mg/L (with a mean value of 2.58 mg/L) and 0.60~2.43 mg/L (with a mean value of 1.14 mg/L), respectively. Both DOC and POC concentrations decrease with depth in the lake during stratification. Algal activity dominates the variations of DOC and POC in the water column. The considerable enrichment of δ13CDOC with depth in Lake Baihua during the stratified season is most likely due to mineralization and decomposition processes in the deeper water. The 13C values of POC were 13C-depleted progressively with depth during the stratified period because of differences in productivity and sedimentary resuspension between epilimnion and respiration. The consistent δ13C-depletion of POC relative to DOC may have resulted from the fact that the DOC pool was more vulnerable to photodegradation.
Key words: Lake Baihua; stratification; organic carbon; stable carbon isotope
EARTH AND ENVIRONMENT Vol. 42, No.5, Tot No.301, 2014, Page 597-603
