The California Air Resources Board and CalRecycle contracted with researchers at California Polytechnic State University, San Luis Obispo, to perform a detailed assessment of greenhouse gas (methane, nitrous oxide, carbon dioxide, and carbon monoxide) (GHG) and 78 non-methane volatile organic compound (VOC) emissions from landfills in California. Prior to this research, limited field emissions data were available for these gases for intra- and inter-landfill variations in California or elsewhere. In extensive field testing at landfills, the researchers measured methane emissions using aerial instruments (16 landfills) and measured emissions of all 82 GHGs and VOCs using ground-based static flux chambers (five landfills).
Baseline air quality and emissions from the three main categories of covers at active landfills (daily, intermediate, and final) were determined at the five sites over the two main seasons (wet and dry) in California. The minimum and maximum measured fluxes were -3.73 to 96.2 g/m2-day for methane, respectively. The nitrous oxide and trace non-methane VOC fluxes were lower and ranged from -0.00410 to 0.145 and -0.00193 to 1.81g/m2-day, respectively. The main factor that controlled surface flux was cover characteristics. The fluxes generally decreased from daily, to intermediate, then final covers; from high to low permeability covers; and from thin to thick covers.