【有机碳输入和还原环境对土壤中镉流动性的影响】E. Marie Muehe † Irini J. Adaktylou † Martin Obst ‡ Fabian Zeitvogel ‡ Sebastian Behrens † Britta Planer-Friedrich § Ute Kraemer and Andreas Kappler *†. Organic Carbon and Reducing Conditions Lead to Cadmium Immobilization by Secondary Fe Mineral Formation in a pH-Neutral Soil. Environ. Sci. Technol. 2013 47 (23) pp 13430–13439

Abstract

Cadmium (Cd) is of environmental relevance as it enters soils via Cd-containing phosphate fertilizers and endangers human health when taken up by crops. Cd is known to associate with Fe(III) (oxyhydr)oxides in pH-neutral to slightly acidic soils though it is not well understood how the interrelation of Fe and Cd changes under Fe(III)-reducing conditions. Therefore we investigated how the mobility of Cd changes when a Cd-bearing soil is faced with organic carbon input and reducing conditions. Using fatty acid profiles and quantitative PCR we found that both fermenting and Fe(III)-reducing bacteria were stimulated by organic carbon-rich conditions leading to significant Fe(III) reduction. The reduction of Fe(III) minerals was accompanied by increasing soil pH increasing dissolved inorganic carbon and decreasing Cd mobility. SEM-EDX mapping of soil particles showed that a minor fraction of Cd was transferred to Ca- and S-bearing minerals probably carbonates and sulfides. Most of the Cd however correlated with a secondary iron mineral phase that was formed during microbial Fe(III) mineral reduction and contained mostly Fe suggesting an iron oxide mineral such as magnet