Trazado geoquímico isotópico de la evolución de rellenos sanitarios, Bariloche, Argentina.

H. OSTERA; S. VALENCIO; R. CORDERO; H. PANARELLO; VILLAROSA, GUSTAVO

San Pablo, Brasil

Simposio; Simposio 40 años de Geocronología no Brasil.; 2004

The accumulation of waste as a byproduct of human activity is one of the greatest environmental matters of modern society. Most of the urban residues are located in landfills, were they are compacted and buried. As product of decomposition of organic matter, these landfills passed trough different stages, which involve four main phases. Each stage is characterized by the production of different gases with distinctive isotope fingerprint. In the first stage of decomposition, the main gas is CO2. N2 content is also high and diminishes along the different stages of evolution, remaining till the oxygen is present. In the second stage, appear H2 and CO2. The third stage starts when the anaerobic bacteria consume the organic acids produced in the previous stage and form acetate. Under these conditions, the landfill presents a neutral environment and the methane generator bacteria can establish. The fourth stage starts when the production and the composition of gas within the landfill remain constant. The principal gases are CO2 and CH4, they are present in similar proportions accompanied by other minor gases like H2S. As the landfills receive waste during long periods of time, usually is possible to determine different degrees of evolution at the different areas of a same landfill. As a consequence, the stage of evolution of a landfill can be detected by the isotope and chemical composition. As part of a multidisciplinary study (EMERS, 2004), the gas geochemistry and isotopic patterns of CO2 were correlated in order to evaluate the different stages in the Bariloche landfill.