Quantification and source apportionment of the methane emission flux from the city of Indianapolis
Quantification and source apportionment of the methane emission flux from the city of Indianapolis
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DOI：
10.12952/journal.elementa.000037
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发表时间：
2015-01-07
影响因子：
3.9
通讯作者：
Richardson, S.
中科院分区：
文献类型：
--
作者：
Cambaliza, M. O. L.;Shepson, P. B.;Richardson, S.
我们报告了印第安纳州印第安纳波利斯市的CH 4排放通量，印第安纳波利斯通量实验（INFIX）项目的开发，评估和改进自上而下和自下而上的方法来量化城市温室气体排放。使用基于飞机的质量平衡方法，我们发现2011年五次飞行实验的平均CH 4排放率为135 +/- 58（1 sigma）mol s（-1）（7800 +/- 3300 kg hr（-1））。印第安纳波利斯的有效人均CH 4排放率为77千克CH 4/人/年，这一数字低于全国人为CH 4排放量（类似于91千克CH 4/人/年），但大大高于全球数字（类似于48千克CH 4/人/年）。我们一直观察到升高的甲烷浓度在特定坐标沿着我们的飞行断面顺风的城市。飞行中的调查以及使用测得的风向的后轨迹表明，浓度升高源自城市的西南侧，垃圾填埋场和天然气输送调节站（TRS）位于那里。街道水平移动的测量顺风的垃圾填埋场和TRS支持的结果-飞机为基础的数据，并被用来量化的相对贡献从两个来源。我们发现，从TRS的CH 4排放量是可以忽略不计的垃圾填埋场，这是负责全市排放通量的33 +/- 10%。从飞机烧瓶样本的丙烷与甲烷的回归表明，剩余的全市甲烷排放量（类似于67%）来自天然气分配系统。我们讨论了地面移动的观测和飞机全市通量测量相结合，以确定总通量和重要源的分配。
We report the CH4 emission flux from the city of Indianapolis, IN, the site of the Indianapolis Flux Experiment (INFLUX) project for developing, assessing, and improving top-down and bottom-up approaches for quantifying urban greenhouse gas emissions. Using an aircraft-based mass balance approach, we find that the average CH4 emission rate from five flight experiments in 2011 is 135 +/- 58 (1 sigma) moles s(-1) (7800 +/- 3300 kg hr(-1)). The effective per capita CH4 emission rate for Indianapolis is 77 kg CH4 person(-1) yr(-1), a figure that is less than the national anthropogenic CH4 emission (similar to 91 kg CH4 person(-1) yr(-1)) but considerably larger than the global figure (similar to 48 kg CH4 person(-1) yr(-1)). We consistently observed elevated CH4 concentrations at specific coordinates along our flight transects downwind of the city. Inflight investigations as well as back trajectories using measured wind directions showed that the elevated concentrations originated from the southwest side of the city where a landfill and a natural gas transmission regulating station (TRS) are located. Street level mobile measurements downwind of the landfill and the TRS supported the results of -aircraft-based data, and were used to quantify the relative contributions from the two sources. We find that the CH4 emission from the TRS was negligible relative to the landfill, which was responsible for 33 +/- 10% of the citywide emission flux. A regression of propane versus methane from aircraft flask samples suggests that the remaining citywide CH4 emissions (similar to 67%) derive from the natural gas distribution system. We discuss the combination of surface mobile observations and aircraft city-wide flux measurements to determine the total flux and apportionment to important sources.