Carbon stable isotopes as indicators of the origin and evolution of CO2 and CH4 in urban solid waste disposal sites and nearby areas

• Published in: Environmental earth sciences 2016-02, Vol.75 (4), p.1, Article 294
• Main Authors: Sanci, Romina, Panarello, Héctor Osvaldo
• Format: Article
• Language: English
• Subjects: Biogeosciences; Carbon; Carbon dioxide; Deuterium; Disposal sites; Earth and Environmental Science; Earth Sciences; Environmental Science and Engineering; Fermentation; Flow system; Geochemistry; Geology; Groundwater flow; Hydrology/Water Resources; Isotopes; Landfill; Methane; Methanogenesis; Original Article; Oxidation; Piezometers; Respiration; Soil contamination; Solid waste disposal; Solid wastes; Stable isotopes; Terrestrial Pollution
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-015-4906-5

Isotopic compositions of CH 4 and CO 2 surface and subsurface gases and groundwater from an urban solid waste disposal site from Gualeguaychú city (Argentina) were measured to detect origin, depth distribution, migration lateral, CH 4 oxidation, and dissolution in groundwater. The highest CH 4 concentrations (60–88 %) with δ 13 C-CH 4 (between −60 and −45 ‰) and δ 2 H-CH 4 (between −350 and −260 ‰) were attributed to CH 4 originated by microbial sources, v. gr. acetate fermentation. The δ 13 C-CO 2 related to this CH 4 (between −15 and −5.9 ‰) were compatible with this process. Also, the increase of DIC associated to an increase in δ 13 C-DIC values (−12.4, −6.4, −5.8, −1.5, +0.1 and +4 ‰) indicated the transport of dissolved gases (from methanogenesis) in the groundwater flow system. High excess deuterium in 3 piezometers suggests that there were hydrogen isotope exchange between CH 4 and water too. Evidences for CH 4 oxidation were decrease in CH 4 concentrations, shift in C and H isotope ratios of CH 4 to more enriched in the remaining CH 4 (in both, δ 13 C-CH 4  >−50 ‰ and δ 2 H >−260 ‰) and depletion in 13 C of the associated CO 2 (