Gillespie Lawson David, Ars Sébastien, Alkadri Samantha, Urya Siyar, Khoo Timothy, Fraser Susan, Vogel Felix, Wunch Debra
Department of Physics, University of Toronto, Toronto, ON, Canada.
Climate Chemistry Measurements and Research, Climate Research Division, Environment and Climate Change Canada, Toronto, ON, Canada.
J Air Waste Manag Assoc. 2025 Feb;75(2):144-163. doi: 10.1080/10962247.2024.2435340. Epub 2025 Jan 9.
We estimate methane emissions for urban waste treatment facilities from mobile in situ atmospheric concentration measurements using an inverse Gaussian plume methodology at facilities in Southern Ontario, Canada. We use these emission rates to assess and improve the existing high-resolution methane inventories for waste sources throughout Southwestern Ontario. Our measurements encompass tens of thousands of kilometres worth of mobile survey data collected over 7 years, including more than 650 downwind transects where we surveyed 14 active landfills, 11 closed landfills, 2 organic waste processing facilities, 3 open-air windrow compost facilities, and 11 water resource recovery facilities. These sources account for 77% of the active landfills within Southern Ontario, which is estimated in inventories to be the largest source of methane emissions in the region. Within the Greater Toronto Area (GTA) megacity, the measured facilities represent about 52% of the total inventoried non-wetland methane emissions. We find that emissions from closed landfills are lower than inventory estimates, with significant implications for the methane budget in the GTA. We update the Facility Level and Area Methane Emissions for the GTA inventory with our measured emissions rates, which results in a 54% decline in the solid waste emissions, effecting a 35% lower estimate for the total anthropogenic methane emissions in the region. We attribute the bulk of this difference to a single facility: the Keele Valley landfill. Our atmospheric measurements serve as a metric for evaluating the discrepancies between four facility level and two high resolution gridded methane emission inventories. We find that the facility level first-order decay model maintained by Environment and Climate Change Canada (ECCC) to be the most consistent with our measured emission rates at landfills, and the self-reported emissions to the Greenhouse Gas Reporting Program of ECCC to be the least consistent with our measurements. We present estimates of atmospheric measurement derived methane emissions for multiple waste processing facilities in Canada. We investigate six emission inventories and models. Based on our atmospheric observations of landfills, we show that the self-reported methane emissions are not well correlated with our measured emissions, and that the first order decay models used in official emissions reporting are much better correlated. One of the most critical findings in this work is that methane emissions from the Keele Valley Landfill, assumed in some inventories to be the second largest anthropogenic source of methane in the country, are significantly less than predicted.
我们利用逆高斯烟羽方法，通过在加拿大安大略省南部的城市垃圾处理设施进行移动原位大气浓度测量，估算这些设施的甲烷排放量。我们使用这些排放率来评估和改进安大略省西南部整个垃圾源现有的高分辨率甲烷排放清单。我们的测量涵盖了7年收集的价值数万公里的移动调查数据，包括650多个下风向断面，在这些断面我们调查了14个现役垃圾填埋场、11个封闭垃圾填埋场、2个有机废物处理设施、3个露天堆肥设施和11个水资源回收设施。这些源占安大略省南部现役垃圾填埋场的77%，在排放清单中估计是该地区最大的甲烷排放源。在大多伦多地区（GTA）这个大城市中，测量的设施占清单中所有非湿地甲烷排放总量的约52%。我们发现封闭垃圾填埋场的排放量低于清单估计值，这对大多伦多地区的甲烷收支有重大影响。我们用测量的排放率更新了大多伦多地区排放清单中的设施级和区域甲烷排放量，这导致固体废物排放量下降了54%，使该地区人为甲烷排放总量的估计值降低了35%。我们将这种差异的大部分归因于一个单一设施：基尔谷垃圾填埋场。我们的大气测量作为一种衡量标准，用于评估四个设施级和两个高分辨率网格化甲烷排放清单之间的差异。我们发现，加拿大环境与气候变化部（ECCC）维护的设施级一阶衰减模型与我们在垃圾填埋场测量的排放率最一致，而向ECCC温室气体报告计划自我报告的排放量与我们的测量最不一致。我们给出了加拿大多个废物处理设施基于大气测量得出的甲烷排放估计值。我们研究了六个排放清单和模型。基于我们对垃圾填埋场的大气观测，我们表明自我报告的甲烷排放量与我们测量的排放量相关性不佳，而官方排放报告中使用的一阶衰减模型相关性要好得多。这项工作中最关键的发现之一是，基尔谷垃圾填埋场的甲烷排放量，在一些清单中被假定为该国第二大人为甲烷排放源，实际上远低于预测值。
