Formation and redox reactivity of ferrihydrite-organic carbon-calcium co-precipitates

摘要: Abstract Complexation with minerals plays a critical role in regulating the stability of organic matter. The presence cations is assumed to be important for complexation between matter and minerals, but there still limited direct analysis formation reactivity mineral-organic matter-cation ternary complexes, as well governing factors fate complexes. In order close this knowledge gap, we investigated ferrihydrite (Fh)-organic carbon (OC)-calcium (Ca) co-precipitates. We performed microbial anaerobic Fe reduction using Shewanella putrefaciens CN32 on synthesized Fh-OC-Ca co-precipitates characterized OC various spectroscopic wet chemistry techniques. found that Ca incorporated into co-precipitate was function OC/iron (Fe) ratio, incorporation not impacted by content. During reduction, favored green rust decreased magnetite siderite high reductive release Fe-bound were controlled primarily C/Fe rather than Ca/Fe ratio. Phenolic preferentially released or degraded during compared aromatic carboxylic OC. Collectively, C/Ca data, K-edge extended X-ray absorption fine structure (EXAFS) before after suggest co-precipitates, likely bridges. whereas affected mineral phase transformation Fh Fe. Hence, our results provide novel understanding Ca-based which can valuable building up process-based models cycles metals.