雨季不同土地利用下表层岩溶泉中脂肪酸来源分析

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

为阐述南川表层岩溶泉中溶解性有机质的来源,采用气相色谱-质谱联用仪(GC-MS)对采自南川柏树湾(BQ)、兰花沟(LQ)、后沟(HQ)表层岩溶泉水中的脂肪酸进行定量分析.结果表明,BQ、LQ和HQ中5~7月泉水脂肪酸平均含量分别为14 870、12 912和8 801 ng·L^(-1),脂肪酸组成均表现为饱和直链脂肪酸>单不饱和脂肪酸>支链脂肪酸>多不饱和脂肪酸,在检测到的脂肪酸中,单体脂肪酸以C16:0、C18:0含量最高,BQ、LQ、HQ中5~7月脂肪酸总浓度随时间推移呈升高趋势.各泉域植被覆盖和基岩裸露率不同,以及降雨带来的稀释作用与土壤迁移增大效应相互作用引起脂肪酸含量和组分变化.通过分析3口表层岩溶泉水中的脂肪酸分布特征和特征参数H/L、CPIh、TARFA,及细菌源、浮游植物源、陆源高等植物源脂肪酸含量发现,兰花沟泉脂肪酸5月以高等植物源为主,7月后沟泉脂肪酸以藻类来源为主,其他月的兰花沟、后沟泉、柏树湾泉的5~7月脂肪酸主要来自于细菌.

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 14 870,12 912 and 8 801 ng·L-1 from May to July,respectively,and followed the order of SFA 〉MUFA〉 Br FA 〉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,CPIh,TARFA 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.