Fluorescence characteristics of dissolved organic matter in the deep waters of the Okhotsk Sea and the northwestern North Pacific Ocean
Fluorescence characteristics of dissolved organic matter in the deep waters of the Okhotsk Sea and the northwestern North Pacific Ocean
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DOI：
10.1016/j.dsr2.2010.02.016
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发表时间：
2010-08-15
影响因子：
3
通讯作者：
Jaffe, Rudolf
中科院分区：
文献类型：
--
作者：
Yamashita, Youhei;Cory, Rose M.;Jaffe, Rudolf
荧光溶解有机物（DOM）是发色DOM的一部分，已知在深海中产生，被认为是生物难降解的。然而，控制深海DOM荧光特性的因素仍然没有得到很好的理解。利用激发-发射矩阵（EEM）荧光和平行因子分析（PARAFAC）方法，对鄂霍次克海和北太平洋西北部深层沃茨中DOM的荧光特性进行了研究。EEM-PARAFAC鉴定出一种蛋白质样成分、两种腐殖酸样成分和一种可能来自荧光计伪影的不确定成分。类蛋白质成分的荧光强度水平最高的表面沃茨，随深度下降，但没有系统地改变在深海层（1000米-底部）。这两个类腐殖酸组分的荧光特性与传统定义的海洋和陆地类腐殖酸荧光团相似。两种类腐殖酸成分的荧光强度水平在表层沃茨最低，在中层（200 - 1 000米）随深度增加，然后在深海层随深度略有下降。与表层相比，深海层中两种腐殖类组分的比例保持在相对较窄的范围内，表明深海层中腐殖类荧光团的组成相似。此外，两个类腐殖酸组分的荧光强度呈线性相关的表观氧利用率（AOU）在深海层，这表明这两个类腐殖酸组分是在原位产生的有机物被生物氧化。这些发现意味着，腐殖类荧光团的光学特性一旦形成，可能不会在深海中进一步改变生物或地球化学。另一方面，荧光强度与AOU和Fe（III）溶解度的关系是不同的两个类腐殖酸组分在中层，这表明不同的环境动力学和生态地球化学作用的两个类腐殖酸组分。(C)2010爱思唯尔有限公司版权所有。
Fluorescent dissolved organic matter (DOM), a fraction of chromophoric DOM, is known to be produced in the deep ocean and is considered to be bio-refractory. However, the factors controlling fluorescence properties of DOM in the deep ocean are still not well understood. In this study, we determined the fluorescence properties of DOM in the deep waters of the Okhotsk Sea and the northwestern North Pacific Ocean using excitation-emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC). One protein-like, two humic-like components, and one uncertain component, which might be derived from a fluorometer artifact, were identified by EEM-PARAFAC. Fluorescence intensity levels of the protein-like component were highest in the surface waters, decreased with depth, but did not change systematically in the bathypelagic layer (1000 m - bottom). Fluorescence characteristics of the two humic-like components were similar to those traditionally defined as marine and terrestrial humiclike fluorophores. The fluorescence intensity levels of the two humic-like components were lowest in the surface waters, increased with depth in the mesopelagic layer (200 - 1000 m), and then slightly decreased with depth in the bathypelagic layer. The ratio of the two humic-like components remained in a relatively narrow range in the bathypelagic layer compared to that in the surface layer, suggesting a similar composition of humic-like fluorophores in the bathypelagic layer. In addition, the fluorescence intensities of the two humic-like components were linearly correlated to apparent oxygen utilization (AOU) in the bathypelagic layer, suggesting that both humic-like components are produced in situ as organic matter is oxidized biologically. These findings imply that optical characteristics of humic-like fluorophores once formed might not be altered further biologically or geochemically in the deep ocean. On the other hand, relationships of fluorescence intensities with AOU and Fe(III) solubility were different between the two humic-like components in the mesopelagic layer, suggesting different environmental dynamics and biogeochemical roles for the two humic-like components. (C) 2010 Elsevier Ltd. All rights reserved.