长江中游湖泊CDOM光学特性及其空间分布对比

Chromophoric dissolved organic matter optical characteristics and spatial distribution in the lakes of the middle reaches of the Yangtze River

根据2007年秋季洪湖、东湖和梁子湖的调查结果,分析了长江中游3个典型湖泊CDOM光学特性及其空间分布差异.结果表明:(1)CDOM吸收系数在洪湖最高,梁子湖最低;(2)在洪湖,CDOM吸收系数受陆源影响较大,与悬浮泥沙浓度呈现较好正相关关系,而在梁子湖,CDOM吸收系数主要受到浮游植物降解贡献,与叶绿素浓度具有显著的正相关关系;(3)洪湖与东湖指数函数斜率S值变化不大;梁子湖CDOM吸收系数空间分布差异较大,指数函数斜率S值与400nm波段CDOM吸收系数ag(400)显著负相关.在建立梁子湖CDOM遥感反演模型时,应引入上述指数函数斜率S值与400nm波段CDOM吸收系数之间的线性函数,对CDOM吸收系数的指数模型进行优化.

Chromophoric dissolved organic matter （CDOM） is the colored fraction of the dissolved organic carbon （DOC） pool. According to investigations and filed measurements in Lake Honghu, Lake Donghu, Lake Liangzi in September and October of 2007, optical characteristics and spatial distribution of CDOM in these lakes are analyzed. Results show that CDOM absorption coefficient in Lake Honghu is the highest, with the mean value of the CDOM absorption coefficient at 400rim （as（400）） is 1.45m^-1, while the lowest is in Lake Liangzi, with the mean value of the CDOM absorption coefficient at 400nm is 0.68m^-1. A significantly positive correlation between CDOM absorption coefficient and suspended sediment concentration is found in Lake Honghu. In Lake Liangzi, CDOM absorption coefficient is positive correlated with chlorophyll concentration, which means CDOM in the lake is mainly contributed by Phytoplanktun degradation. The slope （S） in the exponential correlation function does not vary much in Lake Honghu and Lake Donghu. Fulivc acid is the dominated constituent of CDOM in Lake Liangzi, and the absorption coefficient of CDOM vary extremely. There is a negative correlation relationship （-0.9） between S and as（400） in Lake Liangzi.