太湖CDOM紫外吸收特性及其分子量时空分布特征

Spatial-temporal distribution of CDOM molecular weight and its ultraviolet absorb coefficience characteristics in Taihu Lake

基于2006年8月16日、2007年3月28日对太湖梅梁湾15个样点和2007年11～12月对全湖61个样点的有色溶解性有机物(CDOM)吸收系数观测数据,对CDOM分子量相对大小的时空差异及其影响因素进行了分析.结果表明,梅梁湾地区主要富集的是高分子量CDOM,而大太湖地区则较为复杂,北部地区主要是高分子量的CDOM占据主导地位;而在太湖东西部,主要是低分子量的CDOM;南太湖区域,高分子量的CDOM和低分子量的CDOM相对平衡.不同波长范围内CDOM吸收模型的斜率系数(S)值对CDOM的分子组成的敏感性具有一定的差异性,UVR最为敏感,其次是UV-A,再次为UV-B,UV-C最不敏感.梅梁湾CDOM主要影响因素是陆源,陆源影响的强度随季节的变化具有一定的差异,其中8月份最强,其次是3月份,最弱为11月份.

Field measurements were carried out in Meiliang Bay of Taihu Lake on 16th August, 2006, 28th March 2007 and in whole Taihu Lake from November to December 2007 to analyze the spatial-temporal variation of chromophoric dissolved organic matter （CDOM） molecular weight and its influencing factors. High molecular weight CDOM was mainly collective in Meiliang bay. However, distribution of CDOM in whole Talhu Lake was more complicated. The high molecular weight CDOM hold the leading position in northern Taihu Lake, while in the east and west was mainly low-molecular-weight CDOM; The content of high and low molecular weight CDOM in South were in relative balance. The sensitivity of S in different wavelength range to the molecular composition had a certain difference. S in the UVR wavelength range was most sensitive to the CDOM＇s molecular composition, followed by UV-A, UV-B, and UV-C. Terrestrial sources were the primary influencing factors of CDOM in Meiliang Bay. The influencing intensity of terrestrial sources varied with season, and the greatest and weakest influence occurred in August and November, respectively.