| Autor: |
Raman A; Department of Hydrology and Atmospheric Sciences, University of Arizona , Tucson, Arizona 85721, United States., Arellano AF Jr; Department of Hydrology and Atmospheric Sciences, University of Arizona , Tucson, Arizona 85721, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Environmental science & technology [Environ Sci Technol] 2017 Jun 20; Vol. 51 (12), pp. 6829-6838. Date of Electronic Publication: 2017 Jun 12. |
| DOI: |
10.1021/acs.est.7b00161 |
| Abstrakt: |
A ratio-based method is used to characterize anthropogenic elemental carbon (EC a ) using in situ measurements and emissions of carbon monoxide (CO) and nitrogen oxides (NO x ). We use long-term records of ground-based measurements from the U.S. Environmental Protection Agency (EPA) Air Quality System and Interagency Monitoring of Protected Visual Environments to assess the patterns in anthropogenic combustion ratios (ΔEC a /ΔCO and ΔEC a /ΔNO x ) across the U.S. Petroleum Administration for Defense Districts (PADD) regions for the years 2000-2015. We investigate the change in these ratios between the periods 2000-2007 and 2008-2015. Overall, ΔEC a /ΔCO ratios increase by 0.7-82% and ΔEC a /ΔNO x by 6.8-104% across the East and West PADD regions. The urban West showed the largest increase relative to other regions. This is mainly attributed to a 13-23% increase in ΔEC a during the winter and fall seasons and significant reductions in urban ΔNO x (except in winter). We also find that emission ratios derived from the EPA's National Emission Inventory (NEI) overestimate (underestimate) the increase in the observed enhancement ratios in the East (West). Analyses of changes in NEI emissions in the West reveal (a) smaller reductions in NEI emissions for NO x from the off-road sector and (b) an increase in PM 2.5 (particulate matter 2.5 μm or less in diameter) emissions from commercial/residential combustion and smaller reductions in nonroad emissions. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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