[Impacts of Land Use on the Source of Dissolved Fatty Acids in Epikarst Spring During Rainy Season]

Fatty acids were quantitatively analyzed by gas chromatography-mass spectrometer (GC-MS). Dissolved fatty acids were collected from Nanchuan epikarst spring. The results of BQ, LQ, HQ showed that the average contents of fatty acids were 14870, 12912 and 8801 ng·L^-1 from May to July, respectively, and followed the order of SFA> MUFA> BrFA> PUFA. The monomers with highest content were C16:0 and C18:0. From May to July, the fatty acid content increased in BQ , LQ, HQ. The differences in vegetation coverage and bedrock bare rate, as well as the interaction of the dilution effect and soil transfer increase, led to the changes in content and the composition of the fatty acids. Based on the molecular characteristic indices of fatty acids, like H/L, CPI_h, TAR_FA about BQ, LQ, HQ, and contents of fatty acids which were mainly originated from bacteria, phytoplankton or terrigenous higher plant, it was indicated that fatty acids were mainly originated from higher plant in LQ in May, from phytoplankton input in HQ in July, while from bacteria in the other months in LQ, HQ and from May to July in BQ.