Projected ozone trends and changes in the ozone-precursor relationship in the South Coast Air Basin in response to varying reductions of precursor emissions
Projected ozone trends and changes in the ozone-precursor relationship in the South Coast Air Basin in response to varying reductions of precursor emissions
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DOI：
10.1080/10962247.2015.1106991
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发表时间：
2016-01-01
影响因子：
2.7
通讯作者：
Perea, Roberto
中科院分区：
文献类型：
--
作者：
Fujita, Eric M.;Campbell, David E.;Perea, Roberto
这项研究考察了未来氮氧化物(NOx)和挥发性有机化合物(VOC)排放量的不同减少对加利福尼亚州南海岸空气盆地(SoCAB或盆地)内臭氧峰值的位置和大小的影响。由于目前海盆中臭氧的形成受到挥发性有机碳的限制，2030年基线排放量的模式模拟(自2008年起NOx为-61%，VOC为-32%)预测，与2008年基础模拟相比，SOCAB西部和中部的峰值臭氧水平(即NOx不利影响)增加了10-20%。在2030年基线排放量的基础上再减少50%的NOx(从2008年开始减少81%)，预计SOCAB东部的臭氧水平将减少约15%，但西部和中部盆地的臭氧水平与2008年的水平相当。流域臭氧最大值点向西转移到流域人口较多的地区，可能会导致更大的人口加权臭氧暴露，即使所需的NOx削减的缺口也相对较小，除非伴随着超过2030年基线水平的VOC额外削减。一旦致力于以NOx为重点的控制战略，要达到臭氧国家环境空气质量标准(NAAQS)，就必须从2008年的水平减少超过90%的NOx。这项研究和其他近期工作的结果表明，目前的VOC排放量估计被低估了约50%，这表明，为了达到预计的2030年基线排放量，未来需要更多的VOC减排。将基准年挥发性有机化合物排放量增加1.5倍会导致2008年基线臭氧预测较高，相对响应系数较低，预计设计值降低约20%。如果这些发现是正确的，这些发现将对在SOCAB达到臭氧NAAQS所需的VOC和NOx排放总量和最佳组合产生重要影响。影响：这项研究的结果表明，在计划的以NOx为重点的控制下，SOCAB西部和中部的臭氧水平将保持不变或增加，即使预测的NOx减少的缺口也相对较小。因此，有必要对VOC和NOx的不同减少对臭氧和二次颗粒物的形成和综合健康影响的成本和影响进行严格的分析。鉴于臭氧形成的非线性，这种分析应包括逐渐增加的全球本底臭氧浓度以及该盆地的地形和气象对替代排放控制战略的实际限度的影响。
This study examined the effects of varying future reductions in emissions of oxides of nitrogen (NOx) and volatile organic compounds (VOC) on the location and magnitude of peak ozone levels within California's South Coast Air Basin (SoCAB or Basin). As ozone formation is currently VOClimited in the Basin, model simulations with 2030 baseline emissions (-61% for NOx and -32% for VOC from 2008) predict 10-20% higher peak ozone levels (i.e., NOx disbenefit) in the western and central SoCAB compared with the 2008 base simulation. With additional NOx reductions of 50% beyond the 2030 baseline emissions (-81% from 2008), the predicted ozone levels are reduced by about 15% in the eastern SoCAB but remain comparable to 2008 levels in the western and central Basin. The Basin maximum ozone site shifts westward to more populated areas of the Basin and will result potentially in greater population-weighted exposure to ozone with even a relatively small shortfall in the required NOx reductions unless accompanied by additional VOC reductions beyond 2030 baseline levels. Once committed to a NOx-focused control strategy, NOx reductions exceeding 90% from 2008 levels will be necessary to attain the ozone National Ambient Air Quality Standards (NAAQS). The findings from this study and other recent work that the current VOC emission estimates are underestimated by about 50% suggest that greater future VOC reductions will be necessary to reach the projected 2030 baseline emissions. Increasing the base year VOC emissions by a factor of 1.5 result in higher 2008 baseline ozone predictions, lower relative response factors, and about 20% lower projected design values. If correct, these findings have important implications for the total and optimum mix of VOC and NOx emission reductions that will be required to attain the ozone NAAQS in the SoCAB.Implications: Results of this study indicate that ozone levels in the western and central SoCAB would remain the same or increase with even a relatively small shortfall in the projected NOx reductions under planned NOx-focused controls. This possibility, therefore, warrants a rigorous analysis of the costs and effects of varying reductions of VOC and NOx on the formation and combined health impacts of ozone and secondary particles. Given the nonlinearity of ozone formation, such analyses should include the implications of gradually increasing global background ozone concentrations and the Basin's topography and meteorology on the practical limits of alternative emission control strategies.