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.
Residual impacts of a wildland urban interface fire on urban particulate matter and dust: a study from the Marshall Fire
The impacts of wildfires along the wildland urban interface (WUI) on atmospheric particulate concentrations and composition are an understudied source of air pollution exposure. To assess the residual impacts of the 2021 Marshall Fire (Colorado), a wildfire that predominantly burned homes and other human-made materials, on homes within the fire perimeter that escaped the fire, we performed a combination of fine particulate matter (PM2.5) filter sampling and chemical analysis, indoor dust collection and chemical analysis, community scale PurpleAir PM2.5 analysis, and indoor particle number concentration measurements. Following the fire, the chemical speciation of dust collected in smoke-affected homes in the burned zone showed elevated concentrations of the biomass burning marker levoglucosan (medianlevo = 4147 ng g−1), EPA priority toxic polycyclic aromatic hydrocarbons (median Σ16PAH = 1859.3 ng g−1), and metals (median Σ20Metals = 34.6 mg g−1) when compared to samples collected in homes outside of the burn zone 6 months after the fire. As indoor dust particles are often resuspended and can become airborne, the enhanced concentration of hazardous metals and organics within dust samples may pose a threat to human health. Indoor airborne particulate organic carbon (median = 1.91 μg m−3), particulate elemental carbon (median = .02 μg m−3), and quantified semi-volatile organic species in PM2.5 were found in concentrations comparable to ambient air in urban areas across the USA. Particle number and size distribution analysis at a heavily instrumented supersite home located immediately next to the burned area showed indoor particulates in low concentrations (below 10 μg m−3) across various sizes of PM (12 nm–20 μm), but were elevated by resuspension from human activity, including cleaning.
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- Award ID(s):
- 2218009
- NSF-PAR ID:
- 10420409
- Date Published:
- Journal Name:
- Air Quality, Atmosphere & Health
- ISSN:
- 1873-9318
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s11869-023-01376-3
