Major deviations of iron complexation during 22 days of a mesoscale iron enrichment in the open Southern Ocean
Major deviations of iron complexation during 22 days of a mesoscale iron enrichment in the open Southern Ocean
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DOI：
10.1016/j.marchem.2005.02.002
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发表时间：
2005-09-01
期刊：
影响因子：
3
通讯作者：
de Baar, HJW
中科院分区：
文献类型：
--
作者：
Boye, M;Nishioka, J;de Baar, HJW
在南大洋大西洋区段进行的为期22天的铁浓缩实验期间，强络合铁的形态与周围的自然水域有很大的偏离。进行了三种铁添加(硫酸亚铁溶液)，导致溶解铁浓度升高(Nishioka，J.，Takeda，S.，de 13aar，H.J.W.，Croot，P.L.，Boye，M.，Laan，P.，Timmermann，K.R.)。在开放的南大洋进行铁浓缩实验期间，不同粒度组分中铁浓度的变化。海洋化学。)和显著的Fe(II)水平(Croot，P.L.，Laan，P.，Nishioka，J.，Strass，V，Cisewski，B.，Boye，M.，Timmermann，K.R.，Bellerby，R.G.，Goldson，L.，Nightingale，P.，de 13aar，H.J.W.，在媒体中。Fe(II)的时空分布。以及EisenEx期间的过氧化氢，EisenEx是一种开放的海洋中尺度铁浓缩。海洋化学)。重复垂直剖面的溶解(滤液和lt；0.2微米)铁(Ill)结合配体表明，在上层水柱中产生了螯合剂的铁肥。非生物过程(化学反应)和诱导生物介导的机制可能是溶解配体的来源，它们要么以无机无定形相存在，要么以强有机螯合剂的形式存在。对超滤样品(<；200 kDa)的离散分析表明，所产生的配体将主要是胶体大小(>；200 kDa-<；0.2微米)，而不是在注铁之前以可溶部分(<；200 kDa)为主。然而，这些胶体配体比可溶性配体存在的时间更短暂，后者的停留时间可能更长。溶解铁络合剂的产量一般小于表面注入混合层中溶解铁的总体增量，留下一部分(约13-40%)的溶解铁不被这些溶解铁络合剂结合。推测该组分可能为无机胶体。如此高的无机胶体浓度出人意料地持续高于无机铁的溶解度极限，说明了这些水域中化学铁循环的特殊特征。显然，通过加入溶解的无机Fe(II)离子使总Fe水平人为增加约数百倍，对海水中Fe的自然物理化学丰度和反应性造成了重大破坏。因此，浮游生物生态系统随后的反应虽然本身是重要的，但不一定代表自然富集物，例如风尘的干或湿沉积。最终，铁(Ill)结合配体和铁浓度的时间变化由EISENEX期间发生的混合事件主导，风暴导致溶解的配体和铁浓度稀释一个数量级以上。这对胶体胶粒(200 kDa；lt；0.2微米)的影响最大，胶体配体和胶体铁水平都大幅下降(Nishioka，J.，Takeda，S.，de Baar，H.J.W.，Croot，P.L.，Boye，M.，Laan，P.，Timmermann，K.R.)。在开放的南大洋进行铁浓缩实验期间，不同粒度组分中铁浓度的变化。海洋化学)。(C)2005 Elsevier B.V.保留所有权利。
The speciation of strongly chelated iron during the 22-day course of an iron enrichment experiment in the Atlantic sector of the Southern Ocean deviates strongly from ambient natural waters. Three iron additions (ferrous sulfate solution) were conducted, resulting in elevated dissolved iron concentrations (Nishioka, J., Takeda, S., de l3aar, H.J.W., Croot, P.L., Boye, M., Laan, P., Timmermans, K.R., in press. Changes in the concentration of iron in different size fractions during an iron enrichment experiment in the open Southern Ocean. Marine Chemistry.) and significant Fe(II) levels (Croot, P.L., Laan, P., Nishioka, J., Strass, V, Cisewski, B., Boye, M., Timmermans, K.R., Bellerby, R.G., Goldson, L., Nightingale, P., de l3aar, H.J.W., in press. Spatial and Temporal distribution of Fe(II). and H2O2 during EisenEx, an open ocean mescoscale iron enrichment. Marine Chemistry.). Repeated vertical profiles for dissolved (filtrate < 0.2 mu m) Fe(Ill)-binding ligands indicated a production of chelators in the upper water column induced by iron fertilizations. Abiotic processes (chemical reactions) and an inductive biologically mediated mechanism were the likely sources of the dissolved ligands which existed either as inorganic amorphous phases and/or as strong organic chelators. Discrete analysis on ultra-filtered samples (< 200 kDa) suggested that the produced ligands would be principally colloidal in size (> 200 kDa-< 0.2 mu m), as opposed to the soluble fraction (< 200 kDa) which dominated prior to the iron infusions. Yet these colloidal ligands would exist in a more transient nature than soluble ligands which may have a longer residence time. The production of dissolved Fe-chelators was generally smaller than the overall increase in dissolved iron in the surface infused mixed layer, leaving a fraction (about 13-40%) of dissolved Fe not bound by these dissolved Fe-chelators. It is suggested that this fraction would be inorganic colloids. The unexpected persistence of such high inorganic colloids concentrations above inorganic Fe-solubility limits illustrates the peculiar features of the chemical iron cycling in these waters. Obviously, the artificial about hundred-fold increase of overall Fe levels by addition of dissolved inorganic Fe(II) ions yields a major disruption of the natural physical-chemical abundances and reactivity of Fe in seawater. Hence the ensuing responses of the plankton ecosystem, while in itself significant, are not necessarily representative for a natural enrichment, for example by dry or wet deposition of aeolian dust.Ultimately, the temporal changes of the Fe(Ill)-binding ligand and iron concentrations were dominated by the mixing events that occurred during EISENEX, with storms leading to more than an order of magnitude dilution of the dissolved ligands and iron concentrations. This had strongest impact on the colloidal size class (> 200 kDa-< 0.2 mu m) where a dramatic decrease of both the colloidal ligand and the colloidal iron levels (Nishioka, J., Takeda, S., de Baar, H.J.W., Croot, P.L., Boye, M., Laan, P., Timmermans, K.R., in press. Changes in the concentration of iron in different size fractions during an iron enrichment experiment in the open Southern Ocean. Marine Chemistry) was observed. (c) 2005 Elsevier B.V. All rights reserved.