Ethylene Dibromide Mineralization inSoils under Aerobic Conditions

(EDB), whichisagroundwater contaminant inareaswhereitwasonceusedasasoil fumigant, wasshowntobedegraded aerobically bymicroorganisms intwotypes ofsurface soils froman EDB-contaminated groundwater discharge area. Atinitial concentrations of6to8,Ig/liter, EDBwasdegraded inafewdaystonearorbelowthedetection limit of0.02,ug/liter. At15to18mg/liter, degradation wasslower. Bromide ionrelease atthehigher concentrations was1.4+ 0.3and2.1± 0.2molarequivalents forthetwo soils. Experiments with[14C]EDB showed that EDBwasconverted toapproximately equal amounts ofCO2and apparent cellular carbon; only small amounts ofadded14Cwerenotattributable tothese products orunreacted EDB.Theseresults areencouraging, because theyindicate thatgroundwater bacteria mayhasten theremoval ofEDBfromcontaminated aerobic groundwater supplies. Thisreport alsoprovides evidence forsoil-mediated