Biogeochemical reactivity of Fe-organic matter coprecipitates

铁（III）（水合）氧化物与土壤中的有机结合在铁、碳和磷酸盐等营养物质的生物地球化学循环中起着重要作用。在暂时潮湿或淹水的土壤中，这种结合可以通过溶解的有机物（OM）与铁（III）（氢）氧化物（FHOs）的共沉淀形成。目前，哪些因素控制了Fe(III)-OM共沉淀的形成和组成，以及结构性质如何转化为FHO和OM组分的循环，这些都是未知的。因此，该项目的目标是阐明(i)不同环境条件下Fe(III)-OM共沉淀物的结构特性，（ii）在氧化和缺氧条件下，Fe(III)-OM共沉淀物抗溶解的后续稳定性，（III）氧化还原振荡时Fe(III)-OM共沉淀物组成的变化，以及（III）它们对氧阴离子吸附的累积效应。为了实现这些目标，将进行各种批量实验。通过使用多种分析工具，本项目将对酸性和中性临时湿润土壤以及受氧化还原振荡影响的土壤中Fe(III)-OM共沉淀的形成、结构和生物地球化学反应性的非生物和生物控制有一个基本的了解。

Iron(III) (hydr)oxide-organic associations in soils have been recognized to play an important role in the biogeochemical cycling of iron, carbon, and of nutrients like phosphate. In temporarily moist or water-logged soils such associations can form via the coprecipitation of dissolved organic matter (OM) with Fe(III) (hydr)oxides (FHOs). At present, it is generally unknown which factors control the formation and composition of Fe(III)-OM coprecipitates and how the structural properties translate into the cycling of the FHO and OM component involved. The objectives of the project are thus to elucidate (i) the structural properties of Fe(III)- OM coprecipitates under different environmental conditions, (ii) the subsequent stability of Fe(III)-OM coprecipitates against dissolution under both oxic as well as anoxic conditions, (iii) the changes in Fe(III)-OM coprecipitate composition upon redox oscillations, and (iii) their cumulative effects on oxyanion sorption. To achieve these goals, various batch experiments will be conducted. By using multiple analytical tools, this project will gain a fundamental understanding of the abiotic and biotic controls on the formation, structure, and biogeochemical reactivity of Fe(III)-OM coprecipitates in acidic and neutral temporarily moist soils and soils subject to redox oscillations.