Abstract. Our work explores the impact of two important dimensions of landsystem changes, land use and land cover change (LULCC) as well as directagricultural reactive nitrogen (Nr) emissions from soils, on ozone(O3) and fine particulate matter (PM2.5) in terms of air quality overcontemporary (1992 to 2014) timescales. We account for LULCC andagricultural Nr emissions changes with consistent remote sensingproducts and new global emission inventories respectively estimating theirimpacts on global surface O3 and PM2.5 concentrations as well as Nrdeposition using the GEOS-Chem global chemical transport model. Over thistime period, our model results show that agricultural Nr emissionchanges cause a reduction of annual mean PM2.5 levels over Europe andnorthern Asia (up to −2.1 µg m−3) while increasing PM2.5 levels in India, China and the eastern US (up to +3.5 µg m−3). Land cover changes induce small reductions in PM2.5 (up to −0.7 µg m−3) over Amazonia, China and India due to reduced biogenic volatile organic compound (BVOC) emissions and enhanced deposition of aerosol precursor gases (e.g., NO2, SO2). Agricultural Nr emissionchanges only lead to minor changes (up to ±0.6 ppbv) in annual meansurface O3 levels, mainly over China, India and Myanmar. Meanwhile, ourmodel result suggests a stronger impact of LULCC on surface O3 over the time period across South America; the combination of changes in drydeposition and isoprene emissions results in −0.8 to +1.2 ppbv surfaceozone changes. The enhancement of dry deposition reduces the surface ozone level (up to −1 ppbv) over southern China, the eastern US and central Africa. The enhancement of soil NO emission due to crop expansion also contributes to surface ozone changes (up to +0.6 ppbv) over sub-Saharan Africa. Incertain regions, the combined effects of LULCC and agricultural Nr emission changes on O3 and PM2.5 air quality can be comparable (>20 %) to anthropogenic emission changes over the same time period. Finally, we calculate that the increase in global agricultural Nr emissions leads to a net increase in global land area (+3.67×106km2) that potentially faces exceedance of the critical Nr load (>5 kg N ha−1 yr−1). Our result demonstrates the impacts of contemporary LULCC and agricultural Nr emission changes on PM2.5 and O3 in terms of air quality, as well as the importanceof land system changes for air quality over multidecadal timescales.
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Impacts of meteorology and emissions on summertime surface ozone increases over central eastern China between 2003 and 2015
Abstract. Recent studies have shown that surface ozone (O3)concentrations over central eastern China (CEC) have increased significantlyduring the past decade. We quantified the effects of changes inmeteorological conditions and O3 precursor emissions on surface O3levels over CEC between July 2003 and July 2015 using the GEOS-Chem model.The simulated monthly mean maximum daily 8 h average O3 concentration(MDA8 O3) in July increased by approximately 13.6 %, from 65.5±7.9 ppbv (2003) to 74.4±8.7 ppbv (2015), comparable to the observedresults. The change in meteorology led to an increase in MDA8 O3 of5.8±3.9 ppbv over the central part of CEC, in contrast to a decreaseof about -0.8±3.5 ppbv over the eastern part of the region. Incomparison, the MDA8 O3 over the central and eastern parts of CECincreased by 3.5±1.4 and 5.6±1.8 ppbv due to the increasedemissions. The increase in averaged O3 in the CEC region resulting fromthe emission increase (4.0±1.9 ppbv) was higher than that caused bymeteorological changes (3.1±4.9 ppbv) relative to the 2003 standardsimulation, while the regions with larger O3 increases showed a highersensitivity to meteorological conditions than to emission changes.Sensitivity tests indicate that increased levels of anthropogenic non-methanevolatile organic compounds (NMVOCs) dominate the O3 increase over theeastern part of CEC, and anthropogenic nitrogen oxides (NOx) mainly increaseMDA8 O3 over the central and western parts and decrease O3 in afew urban areas in the eastern part. Budget analysis showed that netphotochemical production and meteorological conditions (transport inparticular) are two important factors that influence O3 levels over theCEC. The results of this study suggest a need to further assess theeffectiveness of control strategies for O3 pollution in the context ofregional meteorology and anthropogenic emission changes.
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- Award ID(s):
- 1743401
- NSF-PAR ID:
- 10132416
- Date Published:
- Journal Name:
- Atmospheric Chemistry and Physics
- Volume:
- 19
- Issue:
- 3
- ISSN:
- 1680-7324
- Page Range / eLocation ID:
- 1455 to 1469
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/acp-19-1455-2019
