Citation:

Olson, N. AND S. Leduc. Nutrients in smoke: Is there an effect on cyanobacteria in downwind waterbodies? Critical Loads of Atmospheric Deposition Science Committee Meeting, Madison, WI, May 01, 2024.

Impact/Purpose:

Wildfire activity is increasing with a warming climate. Wildfires mobilize chemicals in smoke with potential impacts to communities and ecosystems far downwind. In this study, particulate matter (PM2.5) nutrients were elevated on wildfire smoke days compared to non-smoke days. For example, phosphorus concentrations in smoke from one fire were ∼86,000% higher than days without smoke and reached a maximum value of 0.08 μg m−3. Downwind of several high nutrient fires, remotely sensed cyanobacteria abundances increased in the days following intersection with smoke. This is suggestive of a relationship between nutrients from wildfire smoke and cyanobacteria bloom formation, with potential to impact drinking water and aquatic ecosystems in the western United States and other fire-prone regions. The results are broadly applicable to regional partners, water quality managers, and forest and fire services.

Description:

This is a public presentation on the potential effects of nutrients in smoke on downwind cyanobacteria blooms. Wildfire activity is increasing in the continental U.S. and can be linked to climate change effects, including rising temperatures and more frequent drought conditions. Wildfire emissions and large fire frequency have increased in the western U.S., impacting human health and ecosystems. We linked 15 years (2006–2020) of particulate matter (PM2.5) chemical speciation data with smoke plume analysis to identify PM2.5-associated nutrients elevated in air samples on smoke-impacted days. Most macro- and micro-nutrients analyzed (phosphorus, calcium, potassium, sodium, silicon, aluminum, iron, manganese, and magnesium) were significantly elevated on smoke days across all years analyzed. The largest percent increase was observed for phosphorus. With the exception of ammonium, all other nutrients (nitrate, copper, and zinc), although not statistically significant, had higher median values across all years on smoke vs. non-smoke days. Not surprisingly, there was high variation between smoke impacted days, with some nutrients episodically elevated >10000% during select fire events. Beyond nutrients, we also explored instances where algal blooms occurred in multiple lakes downwind from high-nutrient fires. In these cases, remotely sensed cyanobacteria indices in downwind lakes increased two to seven days following the occurrence of wildfire smoke above the lake. This suggests that elevated nutrients in wildfire smoke may contribute to downwind algal blooms. Since cyanobacteria blooms can be associated with the production of cyanotoxins and wildfire activity is increasing due to climate change, this finding has implications for drinking water reservoirs in the western United States, and for lake ecology, particularly alpine lakes with otherwise limited nutrient inputs.

Record Details: