Publication Date:
2017-10-27
Description:
The primary sources for inorganic aerosols from biomass burning are rather negligible; but they are predominantly formed chemically following emission of their precursors (e.g., SO 2 , NH 3, HO x, and NO x ). The biomass burning contributions to some of the precursors can be considerable. Accordingly, we quantify the impact of the emissions on major inorganic aerosols in April-October 2012-2014 using a regional model simulation verified by extensive surface observations throughout the US. Simulated CO enhancements on an hourly basis are used to classify the US into weak-moderate (5〈CO Biomass -CO Base 〈20 ppbv) and strongly impacted periods (CO Biomass -CO Base 〉20 ppbv). This separation not only facilitates the identification of the spatial frequency of the impact but also helps to filter out non-impacted periods, enabling us to focus on long-term contributions. Despite the nonlinear responses of several trace gases to emissions, we observe increases (weak-moderate, strong) in daily surface SO 4 2- (1.16±0.32, 6.57±4.65 nmol/m 3 ), NO 3 - (0.36±0.63, 4.70±7.05 nmol/m 3 ) and NH 4 + (2.70±0.92, 17.82±15.17 nmol/m 3 ) on a national scale. These primarily resulted from i) increases in daily surface SO 2 (0.02±0.01, 0.10±0.07 ppbv), afternoon OH (1.28±4.24, 12.82±23.76 ppqv), and H 2 O 2 (0.06±0.02, 0.10±0.08 ppbv), which may have accelerated the conversion of S(IV) to S(VI), and ii) increases in daily surface NH 3 (1.08±0.73, 8.61±7.73 nmol/m 3 ) and HNO 3 (1.44±0.48, 7.15±4.25 nmol/m 3 ), which could have produced more particle-phase NH 4 NO 3 . In the West, where atmospheric moisture is limited, enhanced SO 4 2- leaves less available water for NH 4 NO 3 to become ions. Our results suggest that the major inorganic aerosols enhancement (mass) can reach to 23% of that of the carbonaceous aerosols.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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