PT13 Aquatic Ecotoxicology I
Exhibit Hall
8:00 AM - Tuesday
(PT175) Aquatic toxicity of ash from burned vegetation.
Ramsdell, H1, Boyle, T2, 1 Colorado State University, Fort Collins, CO, USA2 US Geological Survey, Fort Collins, CO, USA
ABSTRACT- Concerns about potential aquatic impacts of runoff from areas burned by wildfire have typically focused on sedimentation. High turbidity and structural changes in receiving streams may indeed affect aquatic life but much less is known about the soluble constituents that may pose a direct toxic threat. Alkali and transition metal ions may be expected to be present in runoff in varying amounts depending on the types of vegetation burned and the mineral composition of the soils. As part of an effort to characterize the toxicity of soluble chemical constituents associated with burned vegetation, preliminary studies have been conducted with ash samples obtained from a controlled burn. An aqueous extract was prepared by shaking the ash in moderately hard reconstituted water and filtration. For the initial studies, the pH (initially greater than 11) was adjusted prior to dilution for testing. Acute toxicity of the mixture was determined using larval fathead minnows (Pimephales promelas) and planaria (Dugesia dorotocephela) exposed in 4 and 7 day assays, respectively. Concentrations equivalent to less than 2.5 g ash/L were lethal to both species. These results demonstrate the toxicity of ash extracts without the effects of alkaline pH. Our current work also includes collection of water samples from a watershed potentially impacted by a recent wildfire near Fort Collins, CO. To date, it does not appear that precipitation events have been sufficient to mobilize contaminants associated with the burned vegetation.
Key words: runoff, ash, fire