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Quantifying the Importance of Vehicle Ammonia Emissions in an Urban Area of the Northeastern US Utilizing Nitrogen Isotopes
Atmospheric Chemistry and Physics ( IF 6.3 ) Pub Date : 2022-06-24 , DOI: 10.5194/acp-2022-419 Wendell W. Walters, Madeline Karod, Emma Willcocks, Bok H. Baek, Danielle E. Blum, Meredith G. Hastings
Atmospheric Chemistry and Physics ( IF 6.3 ) Pub Date : 2022-06-24 , DOI: 10.5194/acp-2022-419 Wendell W. Walters, Madeline Karod, Emma Willcocks, Bok H. Baek, Danielle E. Blum, Meredith G. Hastings
Abstract. Atmospheric ammonia (NH3) is a critical component of our atmosphere that contributes to air quality degradation and reactive nitrogen deposition; however, our knowledge of NH3 in urban environments remains limited. Year-long ambient NH3 and related species were measured for concentrations and the nitrogen isotopic compositions (δ15N) of NH3 and particulate ammonium (pNH4+) to understand the temporal sources and chemistry of NH3 in a northeastern US urban environment. We found that urban NH3 and pNH4+ concentrations were elevated compared to regional rural background monitoring stations, with seasonally significant variations. Local and transported sources of NHx (NH3 + pNH4+) were identified using polar bivariate and statistical back trajectory analysis, which suggested the importance of vehicles, volatilization, industry, fuel combustion, and biomass burning emissions. Utilizing a uniquely positive δ15N(NH3) emission source signature from vehicles, a Bayesian stable isotope mixing model indicates that vehicles contribute 30.7±11.6 % (mean±1σ) to the annual background level of urban NHx, with a strong seasonal pattern with higher relative contribution during winter (45.8±13.0 %) compared to summer (20.8±9.7 %). The decrease in the relative importance of vehicle emissions during the summer was suggested to be driven by temperature-dependent NH3 emissions from volatilization sources based on wind direction, back trajectory, and NH3 emission inventory analysis. This work highlights that reducing vehicle NH3 emissions should be considered to improve wintertime air quality in this region.
中文翻译:
利用氮同位素量化美国东北部城市地区车辆氨排放的重要性
摘要。大气中的氨 (NH 3 ) 是我们大气的重要组成部分,会导致空气质量下降和活性氮沉积;然而,我们对城市环境中 NH 3的了解仍然有限。测量了长达一年的环境 NH 3和相关物种的浓度和NH 3和颗粒铵 (pNH 4 + ) 的氮同位素组成 (δ 15 N),以了解美国东北部城市环境中 NH 3的时间来源和化学性质. 我们发现城市 NH 3和 pNH 4 +与区域农村背景监测站相比,浓度升高,具有季节性显着变化。NH x (NH 3 + pNH 4 + ) 的本地和运输来源使用极性双变量和统计反向轨迹分析确定,这表明车辆、挥发、工业、燃料燃烧和生物质燃烧排放的重要性。利用车辆独特的正 δ 15 N(NH 3 ) 排放源特征,贝叶斯稳定同位素混合模型表明车辆对城市 NH x的年背景水平贡献了 30.7±11.6 %(平均值±1σ), 与夏季 (20.8±9.7 %) 相比, 冬季 (45.8±13.0 %) 的相对贡献较高, 具有强烈的季节性模式。根据风向、反向轨迹和 NH 3排放清单分析,表明夏季车辆排放相对重要性的下降是由来自挥发源的与温度相关的 NH 3排放驱动的。这项工作强调应考虑减少车辆 NH 3排放以改善该地区的冬季空气质量。
更新日期:2022-06-24
中文翻译:
利用氮同位素量化美国东北部城市地区车辆氨排放的重要性
摘要。大气中的氨 (NH 3 ) 是我们大气的重要组成部分,会导致空气质量下降和活性氮沉积;然而,我们对城市环境中 NH 3的了解仍然有限。测量了长达一年的环境 NH 3和相关物种的浓度和NH 3和颗粒铵 (pNH 4 + ) 的氮同位素组成 (δ 15 N),以了解美国东北部城市环境中 NH 3的时间来源和化学性质. 我们发现城市 NH 3和 pNH 4 +与区域农村背景监测站相比,浓度升高,具有季节性显着变化。NH x (NH 3 + pNH 4 + ) 的本地和运输来源使用极性双变量和统计反向轨迹分析确定,这表明车辆、挥发、工业、燃料燃烧和生物质燃烧排放的重要性。利用车辆独特的正 δ 15 N(NH 3 ) 排放源特征,贝叶斯稳定同位素混合模型表明车辆对城市 NH x的年背景水平贡献了 30.7±11.6 %(平均值±1σ), 与夏季 (20.8±9.7 %) 相比, 冬季 (45.8±13.0 %) 的相对贡献较高, 具有强烈的季节性模式。根据风向、反向轨迹和 NH 3排放清单分析,表明夏季车辆排放相对重要性的下降是由来自挥发源的与温度相关的 NH 3排放驱动的。这项工作强调应考虑减少车辆 NH 3排放以改善该地区的冬季空气质量。