硝酸盐
缺氧水域
化学
反硝化
铵
环境化学
亚硝酸盐
氨
无机化学
反硝化细菌
非生物成分
鳞片岩
氮气
生态学
吸附
有机化学
生物
针铁矿
作者
Holger Bernt Hansen,Christian Koch,Hanne Nancke-Krogh,Ole K. Borggaard,Jan Sørensen
摘要
Leaching of nitrate from soils and sediments can be reduced in anoxic environments due to denitrification to N2O/N2 or reduction of nitrate to ammonium. While microbial dissimilatory reduction of nitrate to ammonia is well known, it is shown here that this conversion can also proceed at appreciable rates in abiotic systems in the presence of green rust compounds [FeII4FeIII2(OH)12SO4·yH2O]. In the reaction nitrate is stoichiometrically reduced to ammonium, and magnetite (Fe3O4) is the sole Fe-containing product. At a constant pH of approximately 8.25 and 25 °C, the rate expression is given as: d[NH4+]/dt = k[Fe(II)]GR[NO3-],where k = 4.93 × 10-5 ± 0.39 × 10-5 L mol-1 s-1. In anoxic soils and sediments, this reaction may also lead to a nitrate to ammonium reduction, at rates of similar magnitude or even higher than microbial reduction rates. Hence green rust should be considered a possible important reductant for nitrate reduction to ammonium in subsoils, sediments, or aquifers where microbially mediated reduction rates are small.
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