Soil microbial community response to a selenium chronic exposure
Titre du congrès :SETAC Europe 17th Annual Meeting
Ville du congrès :Porto
Date du congrès :20/05/2007
Selenium is an essential trace element for living organisms and is known to become rapidly toxic within a narrow range. Some microorganisms can reduce Se toxicity by reducing the oxidized forms of selenium into insoluble elemental Se or by volatilizing them into methylated selenides. The aim of this study was to investigate the response of soil microbial communities during the incubation of artificially contaminated soils with selenite (SeO32-). Two contrasted soils were studied (a sand and a silty-clay soil) and three contamination levels (Se = 0, 0.008, 8 ppm) were compared. Contaminated soils were incubated for six months under constant temperature and humidity. An organic amendment was supplied after three months of incubation. Responses of the soil microbial communities were screened through respiration rate, bacterial counts, community level physiological profiles (Biolog Ecoplates) and bacterial communities structure (B-RISA). Fluxes of volatile Se were also monitored. The relative sensitivity of these different microbial endpoints for Se contaminated soils risk assessment will be discussed.