Changes in the mineral composition of paddy soils upon redox cycles

研究的目的是阐明与氧化还原条件有关的土壤溶液的矿物转化和组成变化的过程。假设水稻种植年限根据氧化还原状态(记忆效应)来区分可比母质的土壤，这反映在土壤的矿物组合、土壤溶液的化学成分和碳储量上。计划中的工作包括氧化还原条件的现场测量，土壤溶液的分析，以及测试矿物的风化实验，这些测试是按照时间序列对近代(堤防后50至1000年)水稻土与非水稻土进行比较的。将分析最近埋藏的古代(长达3000年)和史前(长达6000年)的水稻土及其非灌溉/耕作土壤的矿物组合的差异。批量实验将提供更多关于氧化还原条件对测试矿物和土壤溶液组成的影响的信息。结果将使用程序代码PHREEQC进行评估，以了解溶质的形态以及可能的矿物相溶解和沉淀，并将提供更好的了解氧化还原条件影响下的矿物转化。

The study objective is to elucidate the processes of mineral transformation and changes in the composition of the soil solution as related to redox conditions. It is assumed that the duration of rice cultivation separates soils of comparable parent materials according to the redox status (memory effect), which is reflected by the mineral assemblage, the chemical composition of soil solution, and the carbon storage. The planned work includes field measurements of redox conditions, analyses of soil solutions and weathering experiments with test minerals along a chronosequence of recent (50 to 1000 years after dyking) paddy soils in comparison with non-paddy soils. Recent, buried ancient (up to 3000 years) and prehistoric paddy soils (up to 6000 years old) and their non-irrigated/cultivated counterparts will be analysed for differences in the mineral assemblage. Batch experiments will provide additional information on effects of redox conditions on test minerals and composition of the soil solution. The results will be evaluated using the program code PHREEQC for speciation of solutes and possible dissolution and precipitation of mineral phases and will provide a better understanding of mineral transformation as affected by redox conditions.