- Student Dissertation or Thesis
Central to the study of stratospheric ozone recovery and climate change, is the ability to predict emissions of Montreal Protocol-restricted halocarbons (MPGs) over the coming decades. The prediction of emissions has become difficult as global production of MPGs has rapidly declined establishing “banks” (MPGs which have been produced but not yet released) as the main emission sources. Both the magnitude and release rate of global banks is quite uncertain. Very few field studies have been conducted to provide estimates of global bank emissions from individual sources within countries. This thesis provides the first known observation-based estimates of CFC-12, CFC-11, CFC-113, and CH3CCl3 emissions in the United States (US) and United Kingdom (UK) from municipal solid waste (MSW) landfills.
With several hundred MSW landfills in both the US and UK, estimating emissions of MPGs from landfills required a targeted approach. Whole landfill mixing ratios and flow rates were sampled monthly at one landfill in southern Massachusetts to provide temporal coverage. Spatial coverage was achieved through one time sampling at seven landfills in Massachusetts and through data provided by nine UK landfills for CFC-12 and CFC-11. Only actively managed MSW landfills were sampled.
US and UK MPG landfill emissions were estimated and compared to recent observation-based estimates of total US and UK MPG emissions to determine the importance of the landfill source. US MPG landfill emissions were estimated to be 0.008 - 0.08 Gg year−1. For all four MPGs, US landfill emissions were 0.6% of total US emissions. The UK landfill emission estimates were 6% and 0.8% of total UK CFC-12 and CFC-11 emissions, respectively. All estimates were accurate to within a factor of 2. This indicates that landfills are not currently a significant source of lingering MPG emissions in the US and UK. The implications are that the majority of MPG emissions in industrialized countries are likely coming from faster emitting sources.