Dissolved organic Fe(III) and Fe(II) complexes in salt marsh porewaters
Dissolved organic Fe(III) and Fe(II) complexes in salt marsh porewaters
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DOI：
10.1016/0016-7037(95)00444-0
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发表时间：
1996-03
影响因子：
5
通讯作者：
G. Luther;P. A. Shellenbarger;P. Brendel
中科院分区：
文献类型：
--
作者：
G. Luther;P. A. Shellenbarger;P. Brendel
1993年6月和7月对盐沼孔隙水进行凝胶分馏，用光谱法测定了Fe（III）和Fe（II）有机配合物。铁（III）是硫化物矿物氧化的重要厌氧氧化剂，通常存在于100-5000分子量（MW）的馏分中，表明腐殖质和其他有机络合剂。铁（II）存在于<100 MW和100 - 5000 MW馏分中，大部分铁（II）存在于较小MW级馏分中。当孔隙水的pH值小于3时，两种形式的铁都随腐殖质析出。当孔隙水样品的pH从5.0降至<3时，< 5000mw馏分的溶解铁浓度降低了2倍，> ~ 5000mw馏分的溶解铁浓度增加了9倍，sephadex凝胶馏分的溶解铁浓度降低了10倍。低pH值归因于严重干旱条件下的硫化物矿物氧化，导致植被沼泽严重干燥。微电极测量表明，o2在2毫米以下未被检测到，铁（III）有机配合物在缺氧水中应该是重要的氧化剂。
Fe(III) and Fe(II) organic complexes were determined by spectroscopic methods after sephadex gel fractionation of salt marsh porewaters during June and July 1993. Fe(III), which is a significant anaerobic oxidant for sulfide mineral oxidation, was typically found in the 100–5000 molecular weight (MW) fraction indicative of humic and other organic complexing agents. Fe(II) was found in both the <100 and the 100–5000 MW fractions with most of the Fe(II) found in the smaller MW class. Both forms of Fe precipitated with humic material when the pH of the porewaters became less than 3. There was a twofold decrease in the <5000 MW fractions, a ninefold increase in the >5000 MW class, and a tenfold decrease in dissolved Fe concentration in sephadex gel fractions as the pH decreased from 5.0 to <3 for porewater samples. Low pH values are attributed to sulfide mineral oxidation from severe drought conditions that caused significant dessication of the vegetated marsh. Microelectrode measurements demonstrated that O2was not detected below 2 mm and that Fe(III) organic complexes should be significant oxidants in anoxic waters.