东平湖CDOM吸收光谱特性及其来源解析

为分析东平湖有色可溶性有机物（CDOM）吸收特性、来源和空间分布的季节变化，分别于2013年8、12月以及2014年3月采集了35个表层水样，分析了各基本水质参数、CDOM吸收系数a（440）]、比吸收系数a^*（440）]和相对分子量参数M值的分布规律及CDOM吸收系数与水质参数之间的相关关系.结果表明：东平湖CDOM吸收系数a（440）呈现出枯水期 > 丰水期 > 平水期的规律，空间分布与CDOM比吸收系数a^*（440）]相似.M值呈现出丰水期 < 平水期 < 枯水期的变化趋势.丰水期CDOM吸收系数与叶绿素a（Chla）具有显著相关关系；丰、平水期两季CDOM吸收系数与DOC存在显著相关关系.丰水期CDOM同时受外源和内源输入的影响，但以内源输入为主，主要来源于浮游植物降解产物；老湖镇湖区外源特征明显.平水期CDOM亦受内源和外源输入的双重影响，但浮游植物的腐烂降解不是CDOM的主要来源；北部湖区以外源输入为主.枯水期CDOM整体表现出较强的自生源特征，但相关分析显示，浮游植物降解并不是CDOM的主要来源，自生源特征可能与挖沙活动导致的悬浮物浓度增高有关；东南湖区因大汶河输入的影响呈现出较强的外源特征.利用东平湖丰、平水期两季CDOM浓度反演DOC浓度具有可行性.

Absorption characteristics and source analysis of the CDOM in Dongping Lake

To investigate the chromophoric dissolved organic matter (CDOM) absorption characteristics, sources and spatial-temporal patterns in Dongping Lake, 35surface water samples were collected in August and December of 2013 and March of 2014, respectively. The water quality parameters, spatial distribution of the CDOM absorption coefficient at 440nm, carbon-specific CDOM absorption coefficienta^*(440)], the value of relative molecular size M, as well as the relationships between the CDOM and water quality parameters were studied. Thea(440)] exhibited that the seasonal pattern was dry season > wet season > level period. The spatial distributions were similar to that ofa^*(440)]. The value of relative molecular size M exhibited that the seasonal pattern followed:dry season > level period > wet season. Significant correlation was found between the CDOM absorption coefficient and Chla in wet period. The correlation between CDOM absorption coefficient and DOC in both wet season and level period is also significant. In wet season, the CDOM was affected by both exogenous and endogenous inputs and endogenous input dominanted the CDOM pool, which mainly came from phytoplankton degradation products. The exogenous characteristics in the area of Laohu Town were obvious. In level period, the CDOM was affected by both exogenous and endogenous inputs, however, the degradation of phytoplankton was not the main source of the CDOM. The CDOM in the Northern lake was dominanted by exogenous input. In dry season, the CDOM was mainly affected by endogenous input, and the degradation of phytoplankton was not the main source of the CDOM. It was speculated that its autogenetic characteristics may be related to the increase of suspended matter caused by dredging activities. The Southeast lake showed strong exogenous characteristics which was influenced by Dawen River. Inferring the concentration of DOC by the CDOM concentration was somehow feasible in the wet season and level period in Dongping Lake.