Observation-based trends in ambient ozone in the Czech Republic over the past two decades

Kód výsledku v IS VaVaI

RIV/00020699:_____/18:N0000019 - isvavai.cz

Výsledek na webu

https://www.sciencedirect.com/science/article/pii/S1352231017307045

DOI - Digital Object Identifier

10.1016/j.atmosenv.2017.10.039

Jazyk výsledku

angličtina

Název v původním jazyce

Observation-based trends in ambient ozone in the Czech Republic over the past two decades

Popis výsledku v původním jazyce

We present the trends in ambient ozone concentrations based on high quality data measured continuously at 26 long-term monitoring sites (9 urban, 17 rural including 10 mountain stations) in the Czech Republic in 1994–2015. We considered annual and summer medians, the 10th and 98th percentiles, maximum daily 8h running mean concentrations and exposure index AOT40F. For all indicators taken into account, our results showed significant decreasing trends for about one half of the examined sites. We obtained similar results for all types of sites. The most pronounced decrease in O3 concentrations was recorded at mountain sites. Namely, at the Šerlich mountain site, with an overall decrease per year in annual median by 0.43 ppb, summer median by 1.17 ppb, maximal daily 8h average by 0.45 ppb, the 10th percentile by 0.62 ppb, and 98th percentile by 0.58 (equally as a the the Churáňov site; and at the Bílý Kříž mountain site with overall decrease in AOT40F by 0.75 ppm h. For sites exhibiting significant decreasing trends, an overall decrease per year in annual median was 0.22 ppb, in summer median 0.41 ppb, in the 10th percentile 0.23 ppb, in the 98th percentile 0.53 ppb, and in AOT40F 0.51 ppb h. Significant increasing trend was detected only in the 10th percentile for mere three sites. Moreover, a consistent decrease in limit value exceedances was detected, with by far the highest violation recorded in the meteorologically exceptional year of 2003. Out of the 26 sites under review, seven have not recorded a significant decreasing trend in O3 in any of the considered statistics. The lack of trends in O3 at these eight sites is associated with changing time patterns in local NO and NO2 emissions: in particular, with the increasing ratio in NO2/NOx. There is an obvious geographical pattern in recorded O3 trends: most of the sites with no trend detected are situated in the North-western region of the CR with numerous energy-producing large emission sources, partly denitrified recently. Our results clearly indicated that, for O3 decrease, the ratio between individual NO and NO2 forms is critical, and that a simultaneous significant decrease in both NO and NO2 concentrations is not a sufficient prerequisite. Apart from changes in car fleet in urban areas or near motorways, this factor might be of particular relevance in formerly highly polluted areas, where emissions from large power plants recently substantially decreased.

Název v anglickém jazyce

Observation-based trends in ambient ozone in the Czech Republic over the past two decades

Popis výsledku anglicky

We present the trends in ambient ozone concentrations based on high quality data measured continuously at 26 long-term monitoring sites (9 urban, 17 rural including 10 mountain stations) in the Czech Republic in 1994–2015. We considered annual and summer medians, the 10th and 98th percentiles, maximum daily 8h running mean concentrations and exposure index AOT40F. For all indicators taken into account, our results showed significant decreasing trends for about one half of the examined sites. We obtained similar results for all types of sites. The most pronounced decrease in O3 concentrations was recorded at mountain sites. Namely, at the Šerlich mountain site, with an overall decrease per year in annual median by 0.43 ppb, summer median by 1.17 ppb, maximal daily 8h average by 0.45 ppb, the 10th percentile by 0.62 ppb, and 98th percentile by 0.58 (equally as a the the Churáňov site; and at the Bílý Kříž mountain site with overall decrease in AOT40F by 0.75 ppm h. For sites exhibiting significant decreasing trends, an overall decrease per year in annual median was 0.22 ppb, in summer median 0.41 ppb, in the 10th percentile 0.23 ppb, in the 98th percentile 0.53 ppb, and in AOT40F 0.51 ppb h. Significant increasing trend was detected only in the 10th percentile for mere three sites. Moreover, a consistent decrease in limit value exceedances was detected, with by far the highest violation recorded in the meteorologically exceptional year of 2003. Out of the 26 sites under review, seven have not recorded a significant decreasing trend in O3 in any of the considered statistics. The lack of trends in O3 at these eight sites is associated with changing time patterns in local NO and NO2 emissions: in particular, with the increasing ratio in NO2/NOx. There is an obvious geographical pattern in recorded O3 trends: most of the sites with no trend detected are situated in the North-western region of the CR with numerous energy-producing large emission sources, partly denitrified recently. Our results clearly indicated that, for O3 decrease, the ratio between individual NO and NO2 forms is critical, and that a simultaneous significant decrease in both NO and NO2 concentrations is not a sufficient prerequisite. Apart from changes in car fleet in urban areas or near motorways, this factor might be of particular relevance in formerly highly polluted areas, where emissions from large power plants recently substantially decreased.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10511 - Environmental sciences (social aspects to be 5.7)

Projekt

—

Návaznosti

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Atmospheric Environment

ISSN

1352-2310

e-ISSN

—

Svazek periodika

172

Číslo periodika v rámci svazku

January

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

11

Strana od-do

157-167

Kód UT WoS článku

000418626800017

EID výsledku v databázi Scopus

—