Urban form strongly mediates the allometric scaling of airshed pollution concentrations
Urban form strongly mediates the allometric scaling of airshed pollution concentrations
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DOI：
10.1088/1748-9326/ab50e3
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发表时间：
2019-12
影响因子：
6.7
通讯作者：
Rob MacKenzie;D. Whyatt;M. Barnes;Gemma Davies;C. Hewitt
中科院分区：
文献类型：
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作者：
Rob MacKenzie;D. Whyatt;M. Barnes;Gemma Davies;C. Hewitt
我们利用英国的3030个城市定居点（约占该地区人口的80%），展示了空气污染物的非点源排放与定居人口之间的异速缩放关系。氮氧化物（NOx）和空气微粒（PM10和PM2.5）呈亚线性缩放（斜率为0.6）。也就是说，大城市的这些污染物的人均排放量低于与分散在较小定居点的相同人口相比的预期排放量。与交通有关的排放按比例分列为小住区道路使用不足造成的一部分和大住区拥挤造成的一部分。我们使用这些排放的比例，以及与城市形态相关的比例，来定量地解释城市大气平均空气污染物浓度如何以及为什么会随着人口的增加而增加。我们预测的浓度随人口的变化呈强烈的亚线性变化，斜率约为排放变化的一半，与欧洲各大城市二氧化氮柱的卫星测量结果一致。我们证明了某一特定聚落的城市形态可能导致该聚落的空气棚内平均空气污染比预期的大得多或小得多。我们扩展了我们的分析，预测当地空气污染热点发生的可能性将与人口呈超线性关系，这是一个可检验的假设，等待合适的数据。我们的分析表明，排放和城市形态的协调管理将大大降低局部污染物热点发生的可能性，同时也将改善气候变化下的城市热岛效应。
We present allometric-scaling relationships between non-point-source emissions of air pollutants and settlement population, using 3030 urban settlements in Great Britain (home to ca. 80% of the population of that region). Sub-linear scalings (slope 0.6) were found for the oxides of nitrogen (NOx) and microscopic airborne particles (PM10 and PM2.5). That is, emissions of these pollutants from larger cities are lower per capita than would be expected when compared to the same population dispersed in smaller settlements. The scalings of traffic-related emissions are disaggregated into a component due to under-use of roads in small settlements and a fraction due to congestion in large settlements. We use these scalings of emissions, along with a scaling related to urban form, to explain quantitatively how and why urban airshed-average air pollutant concentrations also scale with population. Our predicted concentration scaling with population is strongly sub-linear, with a slope about half that of the emissions scaling, consistent with satellite measurements of NO2 columns over large cities across Europe. We demonstrate that the urban form of a particular settlement can result in the airshed-average air pollution of that settlement being much larger or smaller than expected. We extend our analysis to predict that the likelihood of occurrence of local air pollution hotspots will scale super-linearly with population, a testable hypothesis that awaits suitable data. Our analysis suggests that coordinated management of emissions and urban form would strongly reduce the likelihood of local pollutant hotspots occurring whilst also ameliorating the urban heat island effect under climate change.