Redox processes in the Oderbruch polder groundwater flow system in Germany

Controlled variation of redox conditions in a floodplain soil: Impact on metal mobilization and biomethylation of arsenic and antimony

“…As opposed to many other studies (e.g., Tack et al, 1998;Massmann et al, 2004;Knox et al, 2006;Du Laing et al, 2007;Yu et al, 2007), concentrations of Mn increased with rising E H in our study (Fig. 3f).…”

Trace elements in streambed sediments of floodplains: consequences for water management measures

“…These results correspond to Zachara et al (2001) who found a strong correlation between the reduction of Fe oxyhydroxides under anaerobic redox conditions and the release of trace metals. Certainly, there is a small allochthonous input from the Oder River water but this influence is restricted to the first 10 to 20 m of the bank infiltration path (Massmann et al 2004). However, when the water levels in the Oder are low, the hydraulic situation changes from confined to unconfined conditions with lower trace metal concentrations in the groundwater due to more oxidizing conditions.…”

“…Discharge measurements of the ditch compartment show a rate of 1.5 m 3 day -1 m -2 . The flow field in this region is described in detail by Massmann et al (2004). The interpretation of the modeled flow field indicates that the drainage channel is mainly discharging water from the deeper parts of the aquifer.…”

Repeated Anaerobic Microbial Redox Cycling of Iron

“…Together these studies suggest that microbial Fe cycling communities are likely to be present and active in anoxic soil and sedimentary environments experiencing shifts in organic carbon and nitrate input, analogous to those known to be present in aerobic/anaerobic interfacial environments (6,8,23,47). When inputs of organic carbon are high compared to nitrate, organic carbon oxidation by nitratereducing bacteria exhausts available nitrate, thus allowing microbial Fe(III) reduction to become the predominant TEAP (4,32,34,57). During subsequent periods of reduced organic carbon loading, rates of nitrate resupply may exceed rates of organotrophic nitrate reduction, resulting in the potential for lithotrophic, nitrate-dependent Fe(II) oxidation, e.g., at the redox boundary in nitrate-contaminated aquifers in agricultural areas (17,18,39) or at the fringe of the Fe(III) reduction zone in organic-contaminated aquifers (2,14,56).…”