抚仙湖悬浮颗粒物正构烷烃来源及季节特征

为了探究抚仙湖水体中有机质的正构烷烃来源和时空变化特征，对2016年4月~2017年3月抚仙湖水柱悬浮颗粒物中正构烷烃的分布特征、来源、季节变化特征及其与沉积物中正构烷烃的关系进行了研究.结果表明：抚仙湖水柱悬浮颗粒物中正构烷烃的碳数分布范围在C₁₇~C₃₃之间，呈现以优势峰C₂₇和C₂₉为主的单峰分布模式.在垂直梯度的空间分布上，正构烷烃在变温层和温跃层的浓度高于深水层，最大浓度出现在深20m水层，深层水体中正构烷烃浓度受沉积物再悬浮作用影响微弱；在季节变化上，正构烷烃含量存在明显的季节波动，在10月和4月呈现最高值；其中，中长链正构烷烃（C₂₅、C₂₇和C₂₉）丰度与浮游植物生物量季节变化趋势一致，证明浮游植物是抚仙湖水柱中正构烷烃的主要来源，水温是限制抚仙湖水柱中正构烷烃时空分布的关键因子.浮游植物、流域表土和沉水植物的共同输入是抚仙湖沉积物中正构烷烃C₂₉具有较高丰度的原因，沉积物中正构烷烃（C₃₁和C₂₃）来源相对单一，可以有效指示流域陆源植物和沉水植物输入.本文结果可多应用正构烷烃指标进行抚仙湖长序列钻孔古环境重建研究提供数据支持.

The sources and seasonal variation characteristics of n-alkanes in suspended particulate matter in Fuxian Lake

In order to investigate the sources and spatiotemporal variation characteristics of n-alkanes in organic matter in Fuxian Lake, the distribution characteristics, biological sources and seasonal variations of suspended particulate matter in water columns of Fuxian Lake from April 2016 to March 2017 were studied. The vertical distribution of n-alkanes demonstrated the relative abundance of n-alkanes above the thermocline was higher than that below the thermocline. The maximum concentration of n-alkanes occured in ~20m depth. The relative abundance of n-alkanes in water columns was weakly affected by sediment resuspension. The obvious seasonal fluctuation in n-alkanes with the highest values in October and April can be found. Furthermore, the seasonal variation trends of n-25, n-27, n-29 alkanes were consistent with that of phytoplankton biomass, which illustrated that the phytoplankton was the main source of n-alkanes in water columns of Fuxian Lake. Water temperature was one of the key factors to limit the spatial and temporal distribution of n-alkanes in water columns of Fuxian Lake. All the input from the phytoplanktons, surface soil and submerged plants played an important role for the high abundance of C₂₉in the surface sediments. The n-alkanes (C₃₁ and C₂₃) in the sediments of Fuxian Lake could effectively indicate the input of terrestrial plants and submerged plants. The results were good foundation of paleo-environmental reconstruction in down core sediments based on n-alkanes in Fuxian Lake.