Ultraviolet-visible and fluorescence spectral evidence of natural organic matter (NOM) changes along an estuarine salinity gradient
Ultraviolet-visible and fluorescence spectral evidence of natural organic matter (NOM) changes along an estuarine salinity gradient
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天然有机物 (NOM) 沿河口盐度梯度变化的紫外-可见光和荧光光谱证据
DOI：
10.1007/bf02803386
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
J. Schalles
中科院分区：
文献类型：
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作者：
J. Alberts;M. Takács;J. Schalles
1999 年 7 月，从最大盐楔渗透点上方到沿海盐度对圣玛丽河口进行了横断面测量。所检查的参数——溶解有机碳 (DOC) 含量、254 nm 处的紫外光吸光度和总发光光谱——均不遵循保守混合规则。圣玛丽河天然有机质 (NOM) 不同分子大小部分的特征以及实验室混合实验的结果提供了证据，表明河流 NOM 中较大分子大小的化合物可能会因盐度高达 10 的凝结而损失。河口下游的碳明显增加归因于该地区丰富的沿海沼泽的出口。河流 NOM 的总发光光谱可以用两个峰来描述，分别以围绕340/445 nm 和 230/430 nm 激发/发射波长对 (EEWP)，这是水生腐殖质材料的特征。来自高盐度站的样品在较低发射波长 EEWP 320/424 nm 处表现出峰值，可以将其视为海洋腐殖质材料。在一些高盐度样品中观察到氨基酸-色氨酸样峰的存在，EEWP 300/350 nm。该峰具有高相对荧光强度。据推测，盐沼和附近沿海地区的强烈生物活性是碳添加以及高荧光氨基酸-蛋白质样材料出现的原因。
A transect of the St Marys River estuary from above the point of maximum salt wedge penetration to coastal salinities was conducted in July 1999. None of the parameters examined—dissolved organic carbon (DOC) content, UV light absorbance at 254 nm, and Total Luminescence spectra—follow the rule of conservative mixing. The characteristics of the different molecular size fractions of the St Marys River natural organic matter (NOM), as well as the results of a laboratory mixing experiment, provided evidence that loss of larger molecular size compounds from riverine NOM may occur by coagulation at salinities up to 10. An apparent gain of carbon in the lower estuary was attributed to exports from abundant coastal marshes in this area.The Total Luminescence spectra of the riverine NOM can be described by two peaks, centered respectively around 340/445 nm, and 230/430 nm Excitation/Emission Wavelength Pair (EEWP), which are characteristic of humic materials of aquatic origin. The samples from the high salinity stations exhibit peaks at lower emission wavelength EEWP 320/424 nm, which can be considered as marine humic-like material. The presence of amino acid-tryptophan like peaks were observed, with EEWP 300/350 nm in some of the high salinity samples. This peak was of high relative fluorescence intensity. It is hypothesized that the intense biological activity of the salt marsh and near coastal area is responsible for the carbon addition as well as the appearance of the highly fluorescence amino acid-protein like material.