Effects of several electron donors on tetrachloroethylene dechlorination in anaerobic soil microcosms

Anaerobic microcosms of subsurface soils from three location were used to investigate the separate effects of several electron donors on tetrachloroethylene (PCE) dechlorination activity. The substrates tested were methanol, lactate, acetate and sucrose. Various levels of sulfate-reducing, acetogenic, fermentative, and methanogenic activity were observed in all sediments. PCE dechlorination was detected in all microcosms, but the amount of dehalogenation varied by several orders of magnitude. Trichloroethylene as the primary dehalogenation product; however, small amounts of cis-1,2-dichloroethylene, 1,1-dichloroethylene, and vinyl chloride were also detected in several microcosms. Lactate-amended microcosms showed large amounts of dehalogenation in two of the three sediments. One of the two sediments which showed positive activity with lactate also had large amounts of dehalogenation with methanol. Amendment with formate, acetate, or sucrose resulted in only slight dehalogenation in the three sediments. Elevated levels of dehalogenation were not consistently associated with any observable anaerobic metabolisms (sulfate reduction, acetogenesis, fermentation, or methanogensis).