Iron and Sulfur Chemistry in a Stratified Lake: Evidence for Iron-Rich Sulfide Complexes
Iron and Sulfur Chemistry in a Stratified Lake: Evidence for Iron-Rich Sulfide Complexes
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分层湖中的铁和硫化学：富铁硫化物络合物的证据
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发表时间：
2003
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通讯作者：
Charoenwan Kraiya
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作者：
G. Luther;B. Glazer;Shufen Ma;Robert E. Trouwborst;B. Shultz;G. Druschel;Charoenwan Kraiya
对美国宾夕法尼亚州东北部用于水力发电的人工湖进行了为期四个月的研究，以调查季节性缺氧和发电设备下游输送的硫化物物种的影响。水柱分析表明，该系统是富铁硫化物相比。总铁（II）浓度在浅水层通常至少是总硫化物水平的两倍。原位伏安分析表明，游离Fe（II）作为[Fe（H2O）6]2+或游离H2S作为H2S/HS-要么不存在或在痕量水平，富铁硫化物络合物存在。从原位数据和总Fe（II）和H2S的测量，我们推断，这些富铁的硫化物络合物可能具有化学计量，如Fe 2SH 3+（或聚合形式的这个和其他化学计量）。这些富铁的硫化物络合物出现有关的富铁的FeS矿物，mackinawite溶解，因为IAP计算的数据从离散瓶样品从底部沃茨是类似的pKsp的mackinawite。可溶性硫化铁物种在没有O2的情况下是稳定的（无论是在湖泊沃茨和管道），并在发电过程中运输几英里。然而，铁-硫化物络合物可以与O2反应以氧化硫化物，并且当含有它们的沃茨暴露于动力装置下游的大气时，还可以解离释放挥发性H2S。沉积物分析表明，该湖富含氧化的铁固体（晶体和非晶体）。FeS固体中的Fe浓度较低（<5 μ mol/g干重），黄铁矿浓度范围约等于固体FeS浓度到固体FeS浓度的30倍。黄铁矿化度小于0.12，表明黄铁矿的形成受游离硫化物的限制，游离硫化物可与富铁硫化物络合物反应。
A four month study of a man-made lake used for hydroelectric power generation in northeastern Pennsylvania USA was conducted to investigate seasonal anoxia and the effects of sulfide species being transported downstream of the power generation equipment. Water column analyses show that the system is iron-rich compared to sulfide. Total Fe(II) concentrations in the hypolimnion are typically at least twice the total sulfide levels. In situ voltammetric analyses show that free Fe(II) as [Fe(H2O)6]2+ or free H2S as H2S/HS- are either not present or at trace levels and that iron-rich sulfide complexes are present. From the in situ data and total Fe(II) and H2S measurements, we infer that these iron-rich sulfide complexes may have stoichiometries such as Fe2SH3+ (or polymeric forms of this and other stoichiometries). These iron-rich sulfide complexes appear related to dissolution of the iron-rich FeS mineral, mackinawite, because IAP calculations on data from discrete bottle samples obtained from bottom waters are similar to the pKsp of mackinawite. Soluble iron-sulfide species are stable in the absence of O2 (both in lake waters and the pipeline) and transported several miles during power generation. However, iron-sulfide complexes can react with O2 to oxidize sulfide and can also dissociate releasing volatile H2S when the waters containing them are exposed to the atmosphere downstream of the powerplant. Sediment analyses show that the lake is rich in oxidized iron solids (both crystalline and amorphous). Fe concentrations in FeS solids are low (<5 μmole/grdry wt) and the pyrite concentration ranges from about equal to the solid FeS to 30 times the solid FeS concentration. The degree of pyritization is below 0.12 indicating that pyrite formation is limited by free sulfide, which can react with the iron-rich sulfide complexes.