兴凯湖春季水体悬浮颗粒物和CDOM吸收特性∗

摘要

Field surveys were carried out in the Lake Xingkai( including both the Great Lake Xingkai and the Small Lake Xingkai) in May 2013, and water samples were collected for examination of the absorption features. In the laboratory, tripton and chromo-phoric dissolved organic matter( CDOM) absorption of 20 water samples were measured through quantitative filter technique. Ab-sorption coefficients were used to analyse the absorption characteristics, source, spatial distribution and relative contribution of op-tical active constituents over the range of PAR(400 700 nm). The results showed that the absorption spectra of tripton are similar to nonalgal particles, indicating less phytoplankton presence in the water column. The total particulate absorption is dominated by the nonalgal particles, of which the contribution rate is up to 50% of the total absorption, and Sg is higher than that in water bodies being investigated elsewhere. Positive correlation of the particles was observed within ap(440), ad(440) and total suspended mat-ter, inorganic suspended matter and organic suspended matter, respectively, while weak correlation was recorded in terms of chlo-rophyll-a( Chl. a) compared with results reported in literatures. In the current study, low correlations of the particles were observed within ag(440), Chl. a and dissolve dissolved organic carbon(DOC). This is probably due to the fact that more colorless DOCs are present in the Lake Xingkai. Absorption coefficient and water quality parameters showed insignificant difference between the Great Lake Xingkai and the Small Lake Xingkai, though the latter is greatly impacted by farmland irrigation discharge, fisheries and tourism sewage.%为了分析兴凯湖水体光学活性物质的吸收特性、来源和空间分布以及对400~700 nm范围内总吸收的贡献，于2013年5月对该水体进行野外实验，对水体中浮游藻类、非藻类颗粒物和有色可溶性有机物的吸收特性和水质参数进行测定.结果表明：总悬浮颗粒物的吸收光谱与非藻类颗粒物相似，色素颗粒物含量较少且单一，非藻类颗粒物在总悬浮颗粒物吸收中占主导地位，其贡献率始终在50%以上. CDOM吸收曲线的拟合函数斜率值Sg均高于其它水体.440 nm处总悬浮颗粒物和非藻类颗粒物的吸收系数ap(440)、ad(440)与总悬浮颗粒物、无机悬浮颗粒物和有机悬浮颗粒物浓度相关性均较好，与叶绿素a( Chl. a)浓度的相关性较差.兴凯湖与其它Ⅱ类水体的差异性表现在440 nm处CDOM吸收系数ag(440)与Chl. a浓度、溶解性有机碳(DOC)浓度均无显著相关性，说明DOC以无色部分为主.总体上，大兴凯湖各吸收系数和水质参数均值均低于小兴凯湖，后者水质受农耕区退水及周围渔业、旅游业的影响较大.