不同水文情形下巢湖有色可溶性有机物来源及分布特征

Characterizing Chromophoric Dissolved Organic Matter(CDOM)in Lake Chaohu in Different Hydrologic Seasons

于2018年1月(枯水)、4月(平水)、7月(丰水)对巢湖开展野外观测,探讨不同水文条件下有色可溶性有机物(CDOM)的光谱组成结构及分布特征。结果表明丰水期巢湖溶解性有机碳(DOC)均值(3.90±0.40)mg·L^(-1)与枯水期均值(3.89±0.19)mg·L^(-1)无显著差异(t-test,p>0.05),丰水期S_(275~295)均值(21.48±1.56)μm^(-1)显著大于枯水期均值(19.24±0.98)μm^(-1)(t-test,p<0.001)。平行因子分析得到了4个荧光组分,分别为短波类腐殖质组分C1、类色氨酸组分C2、类酪氨酸组分C3和长波类腐殖质组分C4。TP,TN,Chl-a和DOC浓度与短波类腐殖质组分C1、长波类腐殖质组分C4都呈显著正相关(p<0.01);DOC与类色氨酸组分C2也存在一定正相关(p<0.05)。此外巢湖CDOM的组成与来源有明显的季节差异性,丰水期陆源类腐殖酸输入是巢湖西部湖区CDOM库主要贡献源;平水期湖泊藻类生物降解为重要贡献源。为有效保护巢湖水质,应对十五里河及南淝河流域实施一定的管控措施。

In this paper,water samples were taken from Lake Chaohu in January(dry),April(wet-to-dry transition),and July(wet)to explore the spectral composition and distribution characteristics of chromophoric dissolved organic matter(CDOM)under different hydrologic conditions.Our results showed that there was no significant difference between the mean of dissolved organic carbon(DOC)in the wet season(3.90±0.40)mg·L^(-1)and in the dry season(3.89±0.19)mg·L^(-1).The mean spectral slope of CDOM,i.e.S_(275~295)in the wet season(21.48±1.56)μm^(-1)was significantly higher than that in the dry season(19.24±0.98)μm-1(t-test,p<0.001).Using CDOM fluorescence and parallel factor analysis,four fluorescence components were obtained including a microbial humic-like C1,a tryptophan-like C2,a tyrosine-like C3,and a terrestrial humic-like C4.C1 and C4 increased with increasing TP,TN,Chl-a,and DOC(p<0.01),and we further found a positive relationship between DOC and tryptophan-like C2(p<0.05).There were seasonal differences in the optical component and sources of CDOM in Chaohu.In the wet season,terrestrial humic-rich CDOM contributed primarily while in the wet-to-dry transition season,autochthonous CDOM derived from algal degradation contributed to the lake’s CDOM pool.In order to protect the water quality of the lake effectively,certain control measures should be carried out in the watersheds of the Shiwuli River and the Nanfei River.