The accurate and timely identification of soil morphological indicators of anaerobic conditions is critical for the proper documentation of hydric soils and prolonged soil saturation. Iron monosulfide (FeS) forms under anaerobic conditions following complexation of Fe and reduced S to form insoluble, black to very dark gray (value ≤ 4, chroma ≤ 1) concentrations and/or soil coatings. These features are observable as soft masses or pore linings or are dispersed throughout the soil matrix in the form of concentrated zones of FeS. Variation in soil and environmental conditions result in a wide range of FeS expression from <1 to 100% coverage of the soil matrix. We seek to explain the environmental conditions required for FeS formation and describe diagnostic methods to document FeS in a field setting. Field identification of FeS can be performed through an oxidized color change test (either ambient air or the application of 3% H₂O₂) and via the evolution of H₂S after the application of 1 M HCl. The use of Indicator of Reduction in Soil (IRIS) devices provides additional supporting evidence of S reducing conditions in soils and thus environmental conditions conducive to FeS formation when other necessary constituents are present. The concepts and techniques outlined in this review can serve as useful resources to inform our understanding of belowground redox chemistry and facilitate the accurate identification of FeS in wet soil environments.

中文翻译：

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单硫化铁的鉴定：现场技术为土壤还原条件提供证据

准确，及时地确定厌氧条件下的土壤形态指标对于正确记录含水土壤和延长土壤饱和度至关重要。一氧化铁（FeS）在厌氧条件下形成铁和还原的S，形成不溶的，黑色到极深的灰色（值≤4，色度≤1）浓度和/或土壤覆盖层，然后在厌氧条件下形成。这些特征可观察到为软块或孔隙衬里，或以FeS集中区的形式分散在整个土壤基质中。土壤和环境条件的变化导致FeS表达范围从<1到100％覆盖土壤基质。我们力求解释FeS形成所需的环境条件，并描述诊断方法以在现场环境中记录FeS。₂ O ₂），并在施加1 M HCl后通过H ₂ S放出。土壤还原指标（IRIS）装置的使用提供了土壤中S还原条件的额外支持证据，因此当存在其他必要成分时，也有利于FeS形成的环境条件。本综述中概述的概念和技术可以作为有用的资源，以帮助我们了解地下氧化还原化学，并有助于在潮湿土壤环境中准确鉴定FeS。