Abstract：
Fluorescent dissolved organic matter (fDOM) in the Brahmaputra River water was characterized using excitation-emission matrix fluorescence spectroscopy (EEM) and parallel factor analysis (PARAFAC) model. EEM and PARAFAC model identified five fluorophores (Peak A, C, M, T, Tuv) and four fDOM components (two humic-, tryptophan-, and tyrosine-like) in the Brahmaputra River water. DOC varied between 0.8 and 3.9 mg/L and along with the intensities of the fDOM components showed higher concentration in the pre-monsoon and monsoon than post-monsoon. Higher biological oxygen demand (BOD) and chemical oxygen demand (COD) confirmed the presence of a high amount of organic pollutants in the Brahmaputra River of Bangladesh. Cations and anions concentrations were comparatively lower in the monsoon and pre-monsoon compared to post-monsoon. Mg2+, Na+, and HCO3- ions were predominant; catchments were carbonate mineral-dominated; and the abundance of Na+ and SO42- ions described the presence of uncommon dissolution in the Brahmaputra River. Optical indices described that fDOM components were less aromatic, had low molecular size and weight, terrestrial and biological derived, and were largely affected by microbial decomposition. The Brahmaputra River water was in the higher microbial risk at the pre-monsoon and monsoon than the post-monsoon of the year. Entropy and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methods based water quality index (WQI) was developed using PARAFAC components matrix of DOM. Newly derived WQI showed high seasonal variability of water quality in the Brahmaputra River due to the changes in local hydro-climate.
摘要：
使用激发-发射矩阵荧光光谱（EEM）和平行因子分析（PARAFAC）模型表征了雅鲁藏布江水中的荧光溶解有机物（fDOM）。EEM和PARAFAC模型确定了五个荧光团(峰A，C,M,T,Tuv)和四个fDOM组件(两个幽默-，色氨酸-,和酪氨酸样）在雅鲁藏布江水中。DOC在0.8至3.9mg/L之间变化，并且随着fDOM成分的强度，季风前和季风中的浓度高于季风后。较高的生物需氧量（BOD）和化学需氧量（COD）证实了孟加拉国雅鲁藏布江中存在大量有机污染物。与季风后相比，季风和季风前的阳离子和阴离子浓度相对较低。Mg2+,Na+,和HCO3-离子占主导地位；集水区以碳酸盐矿物为主；Na和SO42-离子的丰度描述了雅鲁藏布江中罕见的溶解现象。光学指数描述了fDOM组分的芳香性较低，具有低分子量和低分子量，陆地和生物衍生，并在很大程度上受到微生物分解的影响。雅鲁藏布江河水在季风前和季风中的微生物风险高于当年季风后。使用DOM的PARAFAC分量矩阵开发了基于理想解决方案相似度（TOPSIS）方法的熵和偏好顺序技术（WQI）。由于当地水文气候的变化，新衍生的WQI显示出雅鲁藏布江水质的季节性变化。
