The environmental effects of lockdown
NO 3 + hv → NO + O 2
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3 P)
NO 3 + hv → NO 2 + O(
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2.1 Effect of Lockdown on General trends of O ₃ and NO x concentrations in the atmosphere of Bournemouth
O3 = blue; NO = orange; NO2 = green; NOx as NO2 = gold
Figure 1. The dailymean concentrations of ozone, NO, NO 2 andNO x as NO 2 in Bournemouth from01/01/19 to 01/07/20. © Crown 2020 copyright Defra via uk-air.defra.gov.uk, licenced under the Open Government Licence (OGL).
Figure 1 shows the varying concentrations of O 3 and some of its precursors from Jan 1 st , 2019 to July 1 st , 2020 (DEFRA). The graph indicates the seasonal cycle of O 3 production over the year: with lower levels during the colder wintertime months (November to early February) and the peak O 3 concentrations reached in the hot summer months. In general, O 3 concentrations in 2020 are slightly higher than in 2019, with the January to July average in 2019 being lower than the average of 2020 so far (62 µg/m³ and 69 µg/m³ respectively). 2020 recorded higher maximum concentrations of ozone than 2019, 139 µg/m³ and 114 µg/m³ respectively. 2020 and 2019 shared roughly the same minimum concentrations of 7-8 µg/m³, but the minima for 2020 were generally lower than those in 2019. Therefore, the data shows that ozone concentration in 2020 were in general higher but also more extreme highs and lows occurred in 2020 compared to 2019. Even in the months of the coronavirus lockdown O 3 levels increased despite the reduction of its precursor, NO x , emission. For NO x gas concentrations in 2020 and 2019 maxima appear early in the year, and within the winter months the highest levels of NO and NO 2 are recorded. There does seem be some decrease in concentration of NO x gases in 2020, especially in the interval of February tomid-June. 2.2More detailed Analysis Ozone and NOx concentrations between Jan 1 st to July 1 st in 2019 and 2020 Daily mean data can be helpful in looking at the general trends of ozone concentrations, however as many of the ways ground level O 3 is produced begin with the photolysis of ozone itself or of one of its precursors (Atkinson, 2000), 11 O 3 tends to follow a diurnal cycle of concentration, with higher
11 Atkinson, R. ‘ Atmospheric Chemistry of VOC and NOx’ . (2000). Atmospheric Environment 34. https://ysuatmsymp.github.io/papers/SNU/SNU_06.pdf.
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