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Chemical speciation of iron in Antarctic waters surrounding free-drifting icebergs

机译：自由漂流冰山周围南极水域中铁的化学形态

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摘要

Free-drifting icebergs in the Southern Ocean may serve as an important source of iron (Fe) to surrounding waters. We studied the chemical speciation of Fe in the waters around several Antarctic icebergs during cruises to the Scotia and Weddell Seas in June 2008 and March 2009. Iron(Ⅱ) was measured by flow injection chemiluminescence, and Fe-binding ligands were determined following the cruises via competitive ligand equilibrium-cathodic stripping voltammetry. Iron(Ⅱ) concentrations were significantly higher within 1 km of the nearest iceberg (146±11 pM; 12±0.8% of total dissolved Fe (DFe)) compared to farther stations (66± 12 pM; 4± 1% of DFe). Iron(Ⅱ) concentrations were significantly positively correlated with incident light levels, indicating a photochemical source. However spatial Fe(Ⅱ) gradients were statistically significant even after accounting for light effects and were stronger than gradients in DFe or phytoplankton biomass. Iron(Ⅱ) was also higher at deeper depths along the iceberg face, suggesting Fe(Ⅱ) is directly released from ice-rafted minerals. Total Fe-binding ligand concentrations were significantly higher closer to icebergs in the fall but not in the winter, when plankton biomass and grazing activity were substantially lower. Ligands were always present in excess of DFe, but ligands were more fully titrated with DFe in the fall. Ligand/DFe ratios were relatively low (1.2-1.7) compared to other Southern Ocean studies, suggesting that ligands were mostly titrated and additional Fe inputs would be prone to scavenging. Conditional stability constants of ligands (K' with respect to Fe') ranged from 10~(11.9) to 10~(12.9). Macrozooplankton grazing pressure was also elevated near icebergs and may have served as a source of Fe(Ⅱ) and ligands. Icebergs appear to affect, directly and indirectly, the speciation of Fe in surrounding waters with potential implications for bioavailability and scavenging behavior.
机译：南大洋的自由漂流冰山可能是向周围水域提供铁的重要来源。我们研究了2008年6月和2009年3月在斯科舍海和韦德海航行期间南极几个冰山周围水域中铁的化学形态。通过流动注射化学发光法测定铁（Ⅱ），并在航行后确定了铁结合配体通过竞争性配体平衡-阴极溶出伏安法。与最近的冰山（66±12 pM; DFe的4±1％）相比，最近的冰山1公里内的铁（Ⅱ）浓度（146±11 pM；占总溶解Fe（DFe）的12±0.8％）明显更高。 。铁（Ⅱ）的浓度与入射光水平呈显着正相关，说明光化学来源。然而，即使考虑了光效应，空间Fe（Ⅱ）梯度也具有统计学意义，并且比DFe或浮游植物生物量中的梯度强。铁（Ⅱ）在沿冰山表面的更深处也较高，表明铁（Ⅱ）是直接从浮冰矿物中释放的。在秋季，浮游生物的生物量和放牧活性明显降低，而与冰山接近的铁结合配体的总浓度显着较高，而冬季则不然。总是存在超过DFe的配体，但秋天会用DFe更充分地滴定配体。与其他南大洋研究相比，配体/ DFe的比率相对较低（1.2-1.7），这表明配体主要是滴定的，并且额外的铁输入很容易被清除。配体的条件稳定性常数（相对于Fe'的K'）为10〜（11.9）至10〜（12.9）。冰山附近的Macrozooplankton放牧压力也升高，可能是Fe（Ⅱ）和配体的来源。冰山似乎直接或间接地影响周围水域中铁的形态，对生物利用度和清除行为具有潜在影响。

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  • 来源
    《Marine Chemistry》 |2012年第2012期|p.81-91|共11页
  • 作者

    Hai Lin; Benjamin S.Twining;

  • 作者单位

    Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, United States;

    Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, United States,Bigelow Laboratory for Ocean Sciences, W. Boothbay Harbor, ME 04575, United States;

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  • 正文语种 eng
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  • 关键词

    southern ocean; scotia sea; weddell sea; biogeochemistry; Fe(Ⅱ); iron complexation;

    机译：南部海洋;斯科蒂亚海;韦德尔海生物地球化学铁（Ⅱ）;铁络合;

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