Climate Research Division, Environment and Climate Change Canada, Toronto M3H 5T4, Ontario, Canada.
Department of Physics, University of Toronto, Toronto ON M5S, Ontario, Canada.
Environ Sci Technol. 2020 Dec 15;54(24):15671-15679. doi: 10.1021/acs.est.0c05386. Epub 2020 Nov 24.
For methane emission reduction strategies in urban areas to be effective, large emitters must be identified. Recent studies in U.S. cities have highlighted the contribution of methane emissions from natural gas distribution networks and end use. We present a methane emission source identification and quantification method for the Greater Toronto Area (GTA), the largest metropolitan area in Canada, using mobile gas monitoring systems. From May 2018 to August 2019, we collected 77 surveys of methane mixing ratios, covering a distance of about 6400 km, and sampled emission plumes from sources such as closed landfills, natural gas compressor stations, and waterways. Our results indicate that inactive landfills emit less than inventory estimates. Despite this discrepancy, we confirm that the waste sector is the largest methane emitter in the GTA. We also report that the frequency of methane leaks from the local distribution system ranges between 4 and 22 leaks per 100 km of roadway in downtown Toronto, which is comparable to the range observed in U.S. cities, which have invested in modern natural gas distribution infrastructure. Last, we find that engineered waterways, whose emissions are currently not reported in inventories, may be a significant source of methane.
为了使城市地区的甲烷减排策略有效，必须确定主要排放源。美国城市的最新研究强调了天然气分配网络和终端使用过程中甲烷排放的贡献。我们使用移动气体监测系统为加拿大最大的大都市区——大多伦多地区（GTA）提出了一种甲烷排放源识别和量化方法。从 2018 年 5 月到 2019 年 8 月，我们进行了 77 次甲烷混合比调查，覆盖了约 6400 公里的距离，并对来自封闭垃圾填埋场、天然气压缩机站和水道等来源的排放羽流进行了采样。我们的结果表明，非活动垃圾填埋场的排放量低于清单估计值。尽管存在这种差异，但我们确认废物部门是 GTA 地区最大的甲烷排放源。我们还报告称，在多伦多市中心，当地分配系统每 100 公里道路的甲烷泄漏频率在 4 到 22 次之间，这与投资于现代化天然气分配基础设施的美国城市观察到的范围相当。最后，我们发现，目前清单中未报告的人工水道可能是甲烷的重要来源。
