Basin scale survey of marine humic fluorescence in the Atlantic: Relationship to iron solubility and H2O2
Basin scale survey of marine humic fluorescence in the Atlantic: Relationship to iron solubility and H2O2
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DOI：
10.1029/2012gb004427
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发表时间：
2013-01-01
影响因子：
5.2
通讯作者：
Croot, P. L.
中科院分区：
文献类型：
--
作者：
Heller, M. I.;Gaiero, D. M.;Croot, P. L.
铁(Fe)是许多不同海洋地区浮游植物生产力的限制营养物质。铁限制的一个关键方面是它在海水中的低溶解度，因为这控制着铁在海洋中的分布和运输。提高铁在海水中的溶解度的过程，无论是通过氧化还原反应还是有机络合作用，都是理解铁的生物地球化学循环的核心。在这项工作中，我们将铁的溶解度测量与沿大西洋子午线的有色溶解有机物(CDOM)荧光的并行因子(PARAFAC)数据分析(PS ANT XXVI-4)相结合，以验证海洋腐殖质荧光是表层海洋中铁的潜在替代的假设。PARAFAC分析显示有4个组分(C1-4)、两个类腐殖质(C2&4)和两个类蛋白质(C1&3)。总体而言，这4种组分与铁的溶解度都没有显著的相关性，尽管类腐殖质成分与铁的溶解度在富铁水中的相关性很弱。我们的分析表明，负责将溶液中的铁保持在真光区的配体既来自再矿化过程，也来自于响应铁胁迫而产生的特定配体，并且不容易与块体CDOM性质相关。腐殖质荧光信号在地表水中急剧减弱，很可能是由于光漂白，尽管与瞬时光产物过氧化氢的相关性很弱，这表明这里确定的荧光成分在光区的寿命更长。
Iron (Fe) is a limiting nutrient for phytoplankton productivity in many different oceanic regions. A critical aspect underlying iron limitation is its low solubility in seawater as this controls the distribution and transport of iron through the ocean. Processes which enhance the solubility of iron in seawater, either through redox reactions or organic complexation, are central to understanding the biogeochemical cycling of iron. In this work we combined iron solubility measurements with parallel factor (PARAFAC) data analysis of Coloured Dissolved Organic Matter (CDOM) fluorescence along a meridional transect through the Atlantic (PS ANT XXVI-4) to examine the hypothesis that marine humic fluorescence is a potential proxy for iron solubility in the surface ocean. PARAFAC analysis revealed 4 components (C1-4), two humic like substances (C2&4) and two protein-like (C1&3). Overall none of the 4 components were significantly correlated with iron solubility, though humic-like components were weakly correlated with iron solubility in iron replete waters. Our analysis suggests that the ligands responsible for maintaining iron in solution in the euphotic zone are sourced from both remineralisation processes and specific ligands produced in response to iron stress and are not easily related to bulk CDOM properties. The humic fluorescence signal was sharply attenuated in surface waters presumably most likely due to photo bleaching, though there was only a weak correlation with the transient photo product H2O2, suggesting longer lifetimes in the photic zone for the fluorescent components identified here.