太湖溶解有机质光谱和氮磷污染的区域分布差异特征

Characteristics of Spatial Distribution Differences of Spectrum of Dissolved Organic Matter and Nitrogen/Phosphorus Pollution in Taihu Lake

对太湖水体溶解有机质三维荧光光谱、紫外吸收系数、溶解性有机碳(DOC)、总氮和总磷的分布特征进行了研究,定量估算了溶解有机质的来源.研究发现:太湖水体溶解有机质的各物理化学参数以及氮磷质量浓度的区域分布特征明显.水体三维荧光光谱显示有2个特征的类蛋白荧光峰,但不同湖区水样荧光峰位置以及强度并不完全一致.ρ(DOC)和荧光强度〔Fn(355)〕与吸收系数(α)有显著的相关性,但其相关关系也存在明显的区域特征.根据有机质光谱学和理化指标的分布特点、梯度变化规律及地理特征要素,将太湖分为4个区域(Ⅰ,Ⅱ,Ⅲ和Ⅳ区),讨论了各区域的特征和变化规律.利用有机质来源与荧光光谱指数的定量关系,估算了溶解有机质的来源贡献率,结果显示,北部湖区城市污水、陆源和生物活动对DOM的来源均有影响,其他湖区DOM以生物作用为主,陆源贡献率均不超过25%.

Based on analysis of three-dimensional excitation emission matrix fluorescence spectroscopy（3DEEM）,UV-absorption coefficient,dissolved organic carbon concentrations of dissolved organic matter（DOM） and distribution characteristic of total nitrogen and total phosphorous,the origins of dissolved organic matter（DOM） in the water of Taihu Lake were quantitatively estimated.Results show that the physico-chemical parameter of DOM,total nitrogen and total phosphorus content varied much in spatial distribution.3DEEM of DOM in aquatic environments have two main fluorescence peaks： peak B and peak S.Both peaks referred to protein-like fluorescence,and the fluorescence intensity and location was different in spatial distribution.Both DOC concentration and F_n（355） showed strong correlation with absorption coefficient at 254 nm,but the correlation varied in spatial distribution.According to the spectroscopy of DOM,the distribution characteristic and gradient variation of the physico-chemical parameter and the geographical characteristic,Taihu Lake was divided into four regions（regionⅠ,Ⅱ,Ⅲ and Ⅳ）.We applied a fluorescence index to quantitatively determine the proportion of the origin of DOM.The sources of DOM in the north of Taihu Lake include municipal sewage,terrestrial nature and biological activity;however,DOM in other parts of Taihu Lake is mainly rooted in biological activity.The contribution of terrestrial nature was less than 25%.