Post-fire water-quality response in the western United States

Cations like calcium, potassium, and magnesium generally follow nutrient trends, increasing after post-fire precipitation events as a function of burned area and burn severity.

“Cations like calcium, potassium, and magnesium generally follow nutrient trends, increasing after post-fire precipitation events as a function of burned area and burn severity (Bitner et al., 2001; Rust et al., 2018; Smith et al., 2011) as they are primarily generated from ash (Ranalli, 2004).”

Proposed mechanisms explaining increased responses of nutrients post-fire include volatilization and deposition, reduced plant and microbial uptake, and increased leaching and runoff into waterbodies.

“Proposed mechanisms explaining increased responses of nutrients post-fire include volatilization and deposition, reduced plant and microbial uptake, and increased leaching and runoff into waterbodies (Emelko et al., 2016; Rust et al., 2018; Smith et al., 2011).”

The reported durations of metal responses were generally less than 5 yr, a finding consistent with that of Rust et al. (2018).

“The reported durations of metal responses were generally less than 5 yr, a finding consistent with that of Rust et al. (2018), which surveyed post-fire water quality responses across multiple watersheds in the western U.S.”

Wildfires can mobilize metals and other inorganic chemicals which are then transported by precipitation events into downstream waters.

“Wildfires can mobilize metals and other inorganic chemicals which are then transported by precipitation events into downstream waters (e.g., see Abraham et al., 2017b; Rust et al., 2018; Smith et al., 2011).”

Increases in metals were observed following fire across biomes, including boreal peatlands, temperate forests, and Mediterranean forests, and from wildfires as well as prescribed burns.

“Increases in metals were observed following fire across biomes, including boreal peatlands (Brown et al., 2013), temperate forests (Rust et al., 2018), and Mediterranean forests (Burton et al., 2016; Nunes et al., 2017), and from wildfires as well as prescribed burns (Harper et al., 2018).”

Elevated arsenic concentrations have been reported in multiple watersheds post-fire in the western U.S.

“Elevated arsenic concentrations have been reported in multiple watersheds post-fire in the western U.S. (Rust et al., 2018).”

Previous reviews have emphasized the problems to water quality posed by sediments, nutrients, and metals, among other chemicals.

“Previous reviews have emphasized the problems to water quality posed by sediments, nutrients, and metals, among other chemicals (e.g., Bladon et al., 2014; Rust et al., 2018; Smith et al., 2011).”

Nutrients and metals were commonly elevated post-fire.

“Similar to the other studies (e.g., Rust et al., 2018, 2019), we found that nutrients and metals were commonly elevated post-fire.”