YANG Haiquan1,2, CHEN Jingan1, LIU Wen3, WANG Jingfu1,2, Lijian4, JI Yongxue1,2, CHEN Yanming3
(1.State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2. University of Chinese academy of sciences, Beijing 100049, China;
3.The Administration Bureau of the Caohai National Natural Reserve, Weining 553100, China;
4.Jinan Environmental Monitoring Center Station, Jinan 250014,China)
Abstract: This study focused on the distribution characteristics and controlling factors of nutrients in sediments of Caohai Lake, a typical plateau wetland in China. Contents of total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) in 17 surface sediments and three sediment cores were analyzed. Results show that the contents of TOC range from 68.64 mg/g to 348.48 mg/g, with an average of 232.98±77.95 mg/g, and the contents of TN range from 9.32 mg/g to 39.96 mg/g, with an average of 25.21±7.58 mg/g, both of which are much higher than other lakes in China. The TOC and TN in surface sediments come mainly from hydrophytes, and their contents are low in nearshore zone whereas high in central area. Contents of TP range from 0.52 mg/g to 1.54 mg/g, which was also higher than most lakes. The TP contents are low in central area but high in nearshore zone and come from sewage and agricultural nonpoint source pollution. Although there are differences for nutrients in sediments cores because of different anthropogenic disturbance and sedimentary environments, contents of TOC, TN, and TP decrease and gradually keep a constant level with increasing depth. The exogenous pollutions and heavy internal loading of nutrient pose a great threat to the water environment of Caohai Lake. Effective measures and ecological restoration should be taken to reduce the external pollution and control the release from sediment. The lush submerged plants in this lake greatly enhance self-purification and restrain the release of nutrient from sediments, and are therefore important for the optimization of submerged plants and restoration of a clear macrophytic-healthy ecosystem in Caohai Lake.
Key words: Caohai Lake; sediment; TOC; TN; TP
EARTH AND ENVIRONMENT Vol. 44, No.3 Tot No.311, 2016, Page 297-303
