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首页> 外文期刊>Aquatic Sciences >Effects of size and origin of natural dissolved organic matter compounds on the redox cycling of iron in sunlit surface waters
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Effects of size and origin of natural dissolved organic matter compounds on the redox cycling of iron in sunlit surface waters

机译：天然溶解有机物的大小和来源对日照地表水中铁的氧化还原循环的影响

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摘要

The effects of size and origin of natural dissolved organic matter compounds (DOM) on the redox cycling of iron were investigated in water samples from a marine system (Strait of Gibraltar), from a freshwater system (Lake of Murten, i.e., Murtensee, Switzerland), and from a "river-to-ocean" system (Rivers Scheldt and Rhine and corresponding estuaries). In the irradiated seawater samples, Fe(Ⅱ) steady-state concentrations ([Fe(Ⅱ)]_(ss)), both as percentage of total dissolved iron and normalized to 1 mg C L~(-1), were higher in the low-molecular-weight (LMW) than in the high-molecular-weight (HMW) DOM fractions, despite higher net rates of H_2O_2 formation in the HMW DOM fractions. Also in the samples from Murtensee, [Fe(Ⅱ)]_(ss), both as percentage of total dissolved iron and normalized to the decadic absorption coefficient at 350 nm (α_(350), unit m~(-1)), were higher in the LMW than in the HMW DOM fractions. Unlike in the seawater sam- ples, however, net rates of H_2O_2 production, normalized to α_(350), were higher in the LMW DOM fractions, as compared to the HMW DOM fractions, indicating a higher efficiency of O_2~(·-) formation with these LMW compounds from Murtensee. Based on the simulation of experimental data with mathematical kinetic modeling, we hypothesize that Fe(Ⅱ) is formed through photolysis of Fe(Ⅲ) complexes in the LMW DOM fractions from the Strait of Gibraltar and from Murtensee and that Fe(Ⅱ) is stabilized by a ligand in the water samples from Murtensee. In the irradiated HMW DOM fractions from the "river-to-ocean" system, [Fe(Ⅱ)]_(ss), normalized to α_(350), were generally higher in the water samples from the Rivers Scheldt and Rhine than in the water samples from their estuaries, suggesting that terrestrially derived DOM has a higher photochemical reactivity towards Fe(Ⅱ) formation than autochthonous DOM.
机译：在来自海洋系统（直布罗陀海峡），淡水系统（Murten湖，即Murtensee，瑞士）的水样中研究了天然溶解有机物化合物（DOM）的大小和来源对铁氧化还原循环的影响。 ），并通过“河流到海洋”系统（施莱德河和莱茵河及相应的河口）进行。在辐照的海水样品中，Fe（Ⅱ）稳态浓度（[Fe（Ⅱ）] _（ss）），以总溶解铁的百分比和归一化为1 mg CL〜（-1）均较高。尽管高分子量DOM馏分中H_2O_2形成的净速率较高，但低分子量（LMW）仍高于高分子量（HMW）DOM馏分。同样在Murtensee的样品中，[Fe（Ⅱ）] _（ss）占总溶解铁的百分比，并归一化为350 nm的十进制吸收系数（α_（350），单位m〜（-1））， LMW中的分子量高于HMW DOM中的分数。但是，与海水样品不同的是，与HMW DOM组分相比，LMW DOM组分中归一化为α_（350）的H_2O_2净生产率高于HMW DOM组分，表明O_2〜（·-）的效率更高。这些来自Murtensee的LMW化合物形成。基于数学动力学模型对实验数据的模拟，我们假设Fe（Ⅱ）是通过光解直布罗陀海峡和Murtensee的LMW DOM组分中的Fe（Ⅲ）配合物而形成的，并且Fe（Ⅱ）是稳定的由Murtensee的水样中的配体在从“河流到海洋”系统辐射的HMW DOM馏分中，归于α_（350）的[Fe（Ⅱ）] _（ss）归一化为α_（350），通常比Scheldt河和莱茵河中的水样要高。从河口抽取的水样本表明，陆生衍生的DOM对Fe（Ⅱ）形成的光化学反应性高于自生DOM。

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