State Environmental Protection Key Laboratory of Estuarine and Coastal Research, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
Environ Sci Pollut Res Int. 2013 Mar;20(3):1762-71. doi: 10.1007/s11356-012-1085-8. Epub 2012 Jul 21.
Fluorescent dissolved organic matter (FDOM) identified in coastal waters within a large salinity range had been widely reported in previous studies, which stated that conservative mixing of terrestrially derived and river-transported FDOM by clear seawaters could account for the relatively low FDOM fluorescence signals in high salinity seawaters. This study aimed at testing the conservative mixing model in high salinity seawaters in a shallow bay (Bohai Bay, China) with low river flow in a dry season. The water showed high salinities varying in a narrow range (30.52 - 2.07), and salinity effects on fluorescence quantum yields therefore less likely introduced complications to fluorescence data analyses. By applying a parallel factor analysis to fluorescence excitation emission matrices of the water samples, we identified a tyrosine-like FDOM component, a tryptophan-like FDOM component, and two humic substances-like FDOM components. Based on a theoretical analysis, we found that dissolved organic carbon concentrations and suspended solid concentrations of the bulk-water samples as well as the maximum fluorescence signals of each identified FDOM component showed spatial distributions that could not be accounted for by the conservative mixing model. Marine autochthonous processes including microbial activities and FDOM releasing from resuspended sediment were likely to be invoked.
荧光溶解有机物（FDOM）在大盐度范围内的沿海水域中被广泛报道，先前的研究表明，通过清澈海水对陆源和河流输送的 FDOM 的保守混合可以解释高盐度海水中相对较低的 FDOM 荧光信号。本研究旨在测试一个浅湾（中国渤海湾）在枯水季节低盐通量条件下的高盐度海水的保守混合模型。该水域的盐度很高，变化范围很窄（30.52-2.07），因此盐度对荧光量子产率的影响不太可能给荧光数据分析带来复杂性。通过对水样的荧光激发-发射矩阵进行平行因子分析，我们确定了一个酪氨酸样 FDOM 成分、一个色氨酸样 FDOM 成分和两个腐殖质样 FDOM 成分。基于理论分析，我们发现，大部分水体样品的溶解有机碳浓度、悬浮固体浓度以及每个鉴定出的 FDOM 成分的最大荧光信号的空间分布不能用保守混合模型来解释。可能需要考虑海洋自生过程，包括微生物活动和再悬浮沉积物中 FDOM 的释放。
