Environmental context. Dissimilatory iron reduction and Carex-produced dissolved organic matter (DOM) have an important influence on Cr(VI) reduction by the Fe(III)-reducing bacterium Enterobacter. The role of Carex DOM and ferrihydrite in the biotransformation of Cr(VI) by the bacterial isolate was investigated. The findings should help underpin the remediation and detoxification of chromium in anaerobic environments, and provide promising insights into the quaternary system of bacterium/Fe(III)/Cr(VI)/DOM.

Environmental context. Biochar produced by agricultural wastes can be used for vanadium treatment, soil fertility improvement and agricultural waste disposal, whereas acid rain leaching may decrease its remediating efficiency of the metal contaminated soil. Therefore, the behaviour of vanadium in soil and changes in soil quality after biochar application were analysed under simulated acid rain leaching. The findings provide insight into acid rain leaching effects on soil quality, vanadium release from soil and biochar remediating efficiency.