Cataloging Information
Ecological - Second Order
Water
Various studies report changes in phosphorus and nitrogen concentrations in surface waters after wildfires; however, we have found no reports which include nutrient data collected during actual wildfire activity. We had an opportunity to collect water chemistry data from several streams as a large (15,500 ha) intense firestorm passed through their watersheds. Phosphorus and nitrogen concentrations increased from 5 to 60 fold over background levels within the first two days of the fire with maximum recorded concentrations for dissolved nutrients reaching as high as 135 ug/L soluble reactive phosphorus, 261 ug/L ammonium, and 61 ug/L and 349 ug/L respectively. Nutrient concentrations declined to background levels typically <5-10 ug/L within several days to several weeks. Experimental evidence suggests that the primary source of phosphorus was from leaching of ash deposited directly into the streams during the firestorm while the primary source of nitrogen appeared to be from diffusion of smoke gases into the stream waters.