Hossein Mohammadzadeh - Groundwater Research Center, Ferdowsi University of Mashhad, Iran & Department of Earth Sciences, University of Ottawa, Canada
Ian Clark - Department of Earth Sciences, University of Ottawa, Canada

In this paper, the δ13C values and concentrations of carbon pools (DOC, DIC, CH4 and acetate) were used to recognize leachate impact on the surrounding groundwater and to evaluate carbon biogeochemistry within the Ottawa landfill plume. The enriched 13CDIC for groundwater (-6.4 ‰ to - 1.0 ‰) confirm that the leachate (+8.8‰ to +10.7‰) has had an impact on aquifers. In addition, in proximal ground water, methane oncentrations are high (~10 mg l-1) and the 13CCH4 values demonstrate reactive loss of acetate in the leachate plume by methanogenic fermentation, and methane oxidation in the plume fringe. Continued reaction of DOC in groundwater is confirmed by deviation from the mixing lines on diagrams of DIC vs. δ13CDIC and DOC vs. δ13CDOC, and by the absence of acetate.

Landfill leachate, 13C stable isotopes, carbon pools (DOC, DIC, CH4, acetate)