ARSENIC REDUCTION · Influence of arsenate adsorption onto Fe- and Al hydroxide mineral surfaces on microbial arsenate reduction rates
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-01-01 → 2008-12-31
- EU contribution
- €183,454
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - ARSENIC REDUCTION (Influence of arsenate adsorption onto Fe- and Al hydroxide mineral surfaces on microbial arsenate reduction rates)
Microbial reduction of arsenate (As(V)) to arsenite (As(III)) may elevate not only the mobility but also the toxicity of arsenic in the environment. Adsorption of As to soil solid phases was shown to slow down As(V) reduction rates. However, despite its importance, the reduction kinetics of adsorbed As(V) by microorganisms is not well-understood. Thus, we studied the As(V) reduction kinetics by Shewanella putrefaciens CN-32 with suspension incubation experiments under different As(V) adsorption conditions. The As(V) reduction kinetics decreased with increasing extent of As(V) adsorption, depending on the nature and concentrations of the mineral sorbents. Desorption of As(V) from the solid phases was faster than the microbial reduction of dissolved As(V), suggesting that the overall rate of As(V) reduction was not limited by desorption kinetics. Microbial As(V) reduction may thus proceed predominantly via desorption and subsequent reduction of dissolved As(V). Microbe-mineral surface interactions were additionally able to mobilize adsorbed As(V), which subsequently accelerated As(V) reduction. Oxyanions (e.g. phosphate) and microbial polysaccharide production can increase As(V) desorption and reduction rates. Increased As(V) reduction kinetics were likely due to higher dissolved As(V) at the early stage of the incubation by phosphate addition and steadily increasing the dissolved As(V) concentration during the entire incubation period by spiking exopolysaccharides. In conclusion, the adsorption behaviour of As(V) strongly affects the microbial As(V) reduction kinetics. To estimate the mobility and speciation of arsenic in natural water-soil systems, the microbe-mineral-arsenic interactions must be considered.
Data: CORDIS, © European Union
Project objective
Due to its chronic toxicity, arsenic (As) in drinking water poses a serious thread to millions of people worldwide. In most cases, As release is thought to result from microbial AsV reduction coupled to surface chemical interactions in the sediments. However, the interdependence of chemical reactions at the mineral-water interface and microbial AsV reduction processes and the biogeochemical conditions leading to As release in sediments are not well understood. This study aims at elucidating the influence of As adsorption reactions on Fe- and Al-hydroxides on the reduction rates of AsV using incubation studies. Factors to be studied include surface loading of AsV, competitive sorption of As, PO4, and SO4, the interaction of As-reducing and Fe-reducing bacteria, and the transferability of results to the complex soil environment. The knowledge generated in this study provides new insight into an important environmental process and is needed for the implementation of powerful strategies to cope with the problem o f large-scale As release from sediments into water worldwide. The applicant has excellent skills in field studies on trace element fluxes and transformation in forest ecosystems as well as in speciation techniques for trace elements in environmental sample s. In the proposed study, the applicant extends his scientific skills in various fields, including surface, soil, and colloid chemistry, mineralogy, microbiology, and various experimental and analytical techniques. It offers the applicant a new and stimulating research environment and contacts to internationally well-known researchers in environmental chemistry and microbiology. Through training and presentations on international conferences, the applicant will improve his communication and presentation ski lls. The fellowship at ETH Zurich allows the applicant to complement its scientific skills and provides the ideal basis for his further research career in environmental sciences.
Original text from CORDIS.
Participants
- EIDGENOSSISCHE TECHNISCHE HOCHSCHULE ZURICH · ZURICHCoordinatorCity levelSwitzerland
Links
Data: CORDIS, © European Union