Schipa Ilenia, Tanzarella Annalisa, Mangia Cristina
Institute of Atmospheric Sciences and Climate, National Research Council, Section of Lecce, Strada prov. Lecce-Monteroni, km 1,2, 73100 Lecce, Italy.
Environ Monit Assess. 2009 Sep;156(1-4):509-23. doi: 10.1007/s10661-008-0501-5. Epub 2008 Sep 2.
Air quality data from a network of 11 monitoring stations in the Apulia region of southern Italy during the summer of 2005 reveal a high frequency of ozone law limit violations. Since ozone is a secondary pollutant, air quality control strategies aimed at reducing ozone concentration are not immediate. Herein, we analyse weekly changes in concentration levels of ozone (O(3)), nitrogen oxides (NO(x)), carbon monoxide (CO), and volatile organic compounds (VOCs), and evaluate how the differences in primary emissions cause changes in the production of ozone. The comparison between weekend and weekday levels of O(3) and its precursors are direct evidence for the existence of the "ozone weekend effect." This effect was observed at all stations with a considerable variation in the overall ozone magnitude, including both traffic stations and non-traffic stations. Data from VOC measurements at traffic stations primarily indicated elevated levels of benzene, toluene, and xylenes (BTX); all of these substances showed an overall decrease over the weekend. A single station indicated levels of non-methane hydrocarbon (NMHC) and PM10, both of which did not demonstrate any weekly cycle. Analysis of weekly and diurnal cycles of O(3), NO(x), CO, NMHC, and PM10 indicates that higher weekend ozone levels result from a reduction in the emission of nitrogen oxides on weekends in VOC-sensitive regimes. This indicates that a reduction in VOC and NO(x) levels would be more effective than NO(x) reduction alone. Our results underscore the need for improved and more efficient VOC measurements.
2005年夏季意大利南部普利亚地区11个监测站的空气质量数据显示，臭氧超标情况频繁发生。由于臭氧是一种二次污染物，旨在降低臭氧浓度的空气质量控制策略并非立竿见影。在此，我们分析了臭氧（O₃）、氮氧化物（NOₓ）、一氧化碳（CO）和挥发性有机化合物（VOCs）浓度水平的每周变化，并评估一次排放差异如何导致臭氧生成的变化。臭氧及其前体在周末和工作日水平的比较是“臭氧周末效应”存在的直接证据。在所有监测站都观察到了这种效应，总体臭氧量有相当大的变化，包括交通监测站和非交通监测站。交通监测站的挥发性有机化合物测量数据主要表明苯、甲苯和二甲苯（BTX）水平升高；所有这些物质在周末总体上都有所下降。一个监测站显示了非甲烷烃（NMHC）和PM10的水平，这两者都没有呈现出任何每周周期。对臭氧、氮氧化物、一氧化碳、非甲烷烃和PM10的每周和日周期分析表明，在对挥发性有机化合物敏感的区域，周末臭氧水平较高是由于周末氮氧化物排放减少所致。这表明降低挥发性有机化合物和氮氧化物水平比单独降低氮氧化物水平更有效。我们的结果强调了改进和更高效地测量挥发性有机化合物的必要性。
