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Abstract The Thomas Fire began on December 4, 2017 and burned 281,893 acres over a 40‐day period in Ventura and Santa Barbara Counties, making it one of California's most destructive wildfires to date. A major rainstorm then caused a flash flood event, which led to the containment of the fire. Both airborne ash from the fire and the runoff from the flash flood entered into the Santa Barbara Basin (SBB). Here, we present the results from aerosol, river, and seawater studies of black carbon and metal delivery to the SBB associated with the fire and subsequent flash flood. On day 11 of the Thomas Fire, aerosols sampled under the smoke plume were associated with high levels of PM2.5, levoglucosan, and black carbon (average: 49 μg/m3, 1.05 μg/m3, and 14.93 μg/m3, respectively) and aerosol metal concentrations were consistent with a forest fire signature. Metal concentrations in SBB surface seawater were higher closer to the coastal perimeter of the fire (including 2.22 nM Fe) than further off the coast, suggesting a dependence on continental proximity rather than fire inputs. On days 37–40 of the fire, before, during, and after the flash flood in the Ventura River, dissolved organic carbon, dissolved black carbon, and dissolved metal concentrations were positively correlated with discharge allowing us to estimate the input of fire products into the coastal ocean. We estimated rapid aerosol delivery during the fire event to be the larger share of fire‐derived metal transport compared to runoff from the Ventura River during the flood event.
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Future Anthropogenic Land Use Change Impacts on Carbonaceous Aerosol and Implications for Climate and Air Quality
Abstract Future anthropogenic land use change (LUC) may alter atmospheric carbonaceous aerosol (black carbon and organic aerosol) burden by perturbing biogenic and fire emissions. However, there has been little investigation of this effect. We examine the global evolution of future carbonaceous aerosol under the Shared Socioeconomic Pathways projected reforestation and deforestation scenarios using the CESM2 model from present‐day to 2100. Compared to present‐day, the change in future biogenic volatile organic compounds emission follows changes in forest coverage, while fire emissions decrease in both projections, driven by trends in deforestation fires. The associated carbonaceous aerosol burden change produces moderate aerosol direct radiative forcing (−0.021 to +0.034 W/m2) and modest mean reduction in PM2.5exposure (−0.11 μg/m3to −0.23 μg/m3) in both scenarios. We find that future anthropogenic LUC may be more important in determining atmospheric carbonaceous aerosol burden than direct anthropogenic emissions, highlighting the importance of further constraining the impact of LUC.
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- Award ID(s):
- 2223070
- PAR ID:
- 10580958
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 52
- Issue:
- 6
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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