渤海湾两条河流及其近岸海域水体中DOM的光谱特征及影响因素

应用三维荧光光谱结合吸收光谱分析，研究了2019年夏季天津市大清河-独流减河水系和河北省黄骅市捷地减河及其河口区水体中溶解有机物（DOM）的空间分布特征、来源及其影响因素。紫外-可见光谱结果表明，研究区水体的SUVA₂₅₄与盐度有显著正相关关系；两条河流的下游水体中S_275-295均值均大于上游和中游。平行因子分析结果表明，两条河流均检测到两种类腐殖质组分C1（240，300/390 nm）和C3（260，335/477 nm）以及一种类蛋白质组分C2（225，275/339 nm）。在大清河-独流减河水系及其近岸海域水体中，这三种组分与盐度呈显著负相关关系，其中由于人为输入（TN和TP含量高，工业排污）影响导致C2与盐度的相关性弱于C1和C3。该水系水体在低盐度时C2的占比高于捷地减河，主要受到工农业废水输入与其支流子牙河汇入的共同影响，而捷地减河主要受农业废污水输入的影响。此外，自然因素（盐度、海水混合）和人为因素（人为输入、筑坝拦截）的不同导致渤海湾两条入海河流中有色溶解有机质（CDOM）的光学特性和混合行为出现显著差异。其中筑坝拦截导致独流减河坝前水体的CDOM平均分子量低于下游水体，并且增强了河口区陆源类腐殖质的去除作用。综上，三维荧光光谱结合平行因子分析能判别河流局部条件的差异对整体CDOM空间分布特征的影响，研究结果可为渤海湾地区河流及河口水体CDOM生物地球化学过程研究提供基础数据。

Spectral Characteristics and Influencing Factors of Dissolved Organic Matter in Two Rivers and Their Coastal Waters in the Bohai Bay

Three-dimensional fluorescence spectroscopy and UV-Vis spectra were used to study the spatial distribution characteristics, sources and influencing factors of DOM in the Daqing-Duliujian River System in Tianjin and the Jiedijian River in Huanghua, Hebei Province as well as their estuaries in the summer of 2019. The results of UV-Vis spectra showed that the SUVA₂₅₄ values of water samples in the study area were positively correlated with the salinity, while the mean S_275-295 values in the downstream water of the two rivers were higher than those in the upstream and midstream water. PARAFAC results showed that the microbial humic-like substances (M-like) of phytoplankton origin (Component 1), the phytoplankton derived protein-like or tryptophan-like (Component 2), and the terrestrial humic-like substances (C-like) of terrestrial origin (Component 3) were detected in the two rivers. In the Daqing-Duliujian River System and its coastal waters, the three components had a significant negative correlation with salinity, but Component 2 (protein like fluorescence intensity) was less correlated with the salinity, compared with the Component 1 and Component 3. It was mainly due to anthropogenic input (high content of TN and TP, industrial sewage) causing an increase in the content of Component 2. In addition, the proportion of Component 2 in the Daqing-Duliujian River System at low salinity was higher than that in the Jiedijian River, which was mainly due to the joint influence of industrial and agricultural wastewater input and the Ziya River tributary inflow in the Duliujian River, while the Jiedijian River was only affected by agricultural wastewater input. The differences of natural factors (salinity, seawater mixing) and human factors (human input, damming and interception) in the two rivers entering the Bohai Bay may lead to significant differences in optical properties and mixing behavior of CDOM. The average molecular weight of DOM in the front of dam located in the Duliujian River was lower than those in the downstream water because of damming, and the damming effect may cause an enhanced removal of microbial humus in the estuary. In conclusion, EEM- PARAFAC analysis can be used to identify the impact of local river conditions on the spatial distribution of CDOM. The results can provide basic data for studying biogeochemical processes of CDOM in rivers and estuaries around the Bohai Bay.