Wildfire Effects on Contaminant Transport through Wind Erosion: Preliminary Results


J. Whicker, J. Pinder, D. Breshears, K. Mack


Over the long times required for many risk assessments, changes in ecosystem properties and dynamics become important. In particular, episodic/high-impact events such as drought, anthropogenic disturbance, and wildfires are likely to happen and could have major impacts on contaminant transport rates. Additionally, contaminant transport rates show threshold and nonlinear responses to changes in key environmental conditions such as vegetation cover. Episodic wildfires are an example where a rapid reduction in vegetation cover could cause significant increases in contaminant transport rates through soil erosion. During the year 2000, there were major wildfires at three DOE sites (Los Alamos National Laboratory, Idaho National Engineering and Environmental Laboratory, and Hanford) that burned over numerous contaminated sites. Yet, there exist little long-term, quantitative information on the role of episodic events (e.g., wildfire) and erosion thresholds on transport rates. For this study, measurements of the effects of wildfire on wind erosion were conducted at Los Alamos National Laboratory (LANL). The preliminary results show that: 1) wildfire increased wind erosion rates significantly at LANL, 2) most wind erosion occurred during high-wind events with threshold wind velocities around 6 m s-1, and 3) distributions of weekly soil flux can be applied to estimate the mean and associated variation in resuspension rates for contaminants of interest from LANL sites. These preliminary results are generally consistent with postfire findings at the Waste Isolation Pilot Plant (Carlsbad, NM) and show the importance of accounting for episodic events, including transport thresholds and nonlinear responses, and measurement of erosion at finer temporal and spatial scales to improve long-term estimates of ecological and human risk.


This abstract was presented at the 35th Annual Midyear Meeting, "Decommissioning and Environmental Restoration", Late Submissions Session, 2/17/2002 - 2/20/2002, held in Orlando, FL.

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