Global trends in the fluorescence characteristics and distribution of marine dissolved organic matter
Global trends in the fluorescence characteristics and distribution of marine dissolved organic matter
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DOI：
10.1016/j.marchem.2011.05.002
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发表时间：
2011-09-20
期刊：
影响因子：
3
通讯作者：
Sondergaard, Morten
中科院分区：
文献类型：
--
作者：
Jorgensen, Linda;Stedmon, Colin A.;Sondergaard, Morten
一小部分溶解的有机物 (DOM) 能够发出荧光。本研究已使用这种能力来研究不同 DOM 分数的特征和分布。一个独特的全球数据集揭示了 DOM 的七种不同的荧光部分：两种腐殖质样、四种氨基酸样和一种化学性质未表征的。类氨基酸级分的光谱特征类似于纯色氨酸、酪氨酸和苯丙氨酸。这些氨基酸样部分的荧光强度在地表水中最高，随着深度的增加而迅速降低，并且在深海层中处于恒定的低水平。这些特征表明，类氨基酸 DOM 与地表水产生有关。根据校准曲线，我们估计地表水色氨酸和酪氨酸的平均浓度分别为 12.5，接近 15.9 nmol L-1，而平均深水浓度为 5.1，接近 6.5 nmol L-1。类腐殖质 DOM 组分的荧光强度在表层较低，在中深海层迅速增加，在深海层保持较高水平。在表面层观察到的低荧光强度表明光化学降解作为类腐殖质化合物的汇的定量重要性。在暗色海洋（200 m以下）中，类腐殖质 DOM 荧光与微生物活性（表观氧利用率、NO3- 和 PO43-）之间存在显着的线性关系。这些观察结果表明与暗海微生物再矿化有关，并表明类腐殖质化合物的主要来源是有机物的微生物周转。本研究的结果表明，类腐殖质 DOM 部分的分布是大陆径流供应、微生物净生产和地表水中光化学去除之间的平衡。 (C) 2011 Elsevier B.V. 保留所有权利。
A fraction of dissolved organic matter (DOM) is able to fluoresce. This ability has been used in the present study to investigate the characteristics and distribution of different DOM fractions. A unique global dataset revealed seven different fluorescent fractions of DOM: two humic-like, four amino acid-like and one chemically uncharacterized. The spectral characteristics of the amino acid-like fractions resemble those of pure tryptophan, tyrosine and phenylalanine. The fluorescence intensities of these amino acid-like fractions are highest in the surface waters, rapidly decreasing with depth and at a constant low level in the bathypelagic layer. Such profiles indicate that amino acid-like DOM is linked to surface water production. From calibration curves we estimated the mean surface water concentrations of tryptophan and tyrosine to be 12.5 and similar to 15.9 nmol L-1, respectively, while mean deep water concentrations are 5.1 and similar to 6.5 nmol L-1. The fluorescence intensities of the humic-like DOM fractions were low in the surface layer, rapidly increasing in the mesopelagic layer and at constant high level in the bathypelagic layer. The low fluorescence intensities observed in the surface layer indicate the quantitative importance of photochemical degradation as a sink of the humic-like compounds. In the dark ocean (below 200 m), significant linear relationships between humic-like DOM fluorescence and microbial activity (apparent oxygen utilization. NO3- and PO43-) were found. These observations imply a link to dark ocean microbial remineralization and indicate that the major source of humic-like compounds is microbial turnover of organic matter. The results of the present study show that the distribution of the humic-like DOM fractions is a balance between supply from continental run off, net microbial production and photochemical removal in surface waters. (C) 2011 Elsevier B.V. All rights reserved.