Pulsed Redistribution of a Contaminant Following Forest Fire: Cesium-137 in Runoff

Mathew P. Johansen, Thomas E. Hakonson, F. Ward Whicker, David D. Breshears

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

Of the natural processes that concentrate dispersed environmental contaminants, landscape fire stands out as having potential to rapidly concentrate contaminants and accelerate their redistribution. This study used rainfall simulation methods to quantify changes in concentration of a widely dispersed environmental contaminant (global fallout 137Cs) in soils and surface water runoff following a major forest fire at Los Alamos, New Mexico, USA. The 137Cs concentrations at the ground surface increased up to 40 times higher in ash deposits and three times higher for the topmost 50 mm of soil compared with pre-fire soils. Average redistribution rates were about one order of magnitude greater for burned plots, 5.96 KBq ha-1 mm-1 rainfall, compared with unburned plots, 0.55 KBq ha-1 mm-1 rainfall. The greatest surface water transport of 137Cs, 11.6 KBq ha-1 mm-1, occurred at the plot with the greatest amount of ground cover removal (80% bare soil) following fire. Concentration increases of 137Cs occurred during surface water erosion, resulting in enrichment of 137Cs levels in sediments by factors of 1.4 to 2.9 compared with parent soils. The elevated concentrations in runoff declined rapidly with time and cumulative precipitation occurrence and approached pre-fire levels after approximately 240 mm of rainfall. Our results provide evidence of order-of-magnitude concentration increases of a fallout radionuclide as a result of forest fire and rapid transport of radionuclides following fire that may have important implications for a wide range of geophysical, ecosystem, fire management, and risk-based issues.

Original languageEnglish (US)
Pages (from-to)2150-2157
Number of pages8
JournalJournal of Environmental Quality
Volume32
Issue number6
StatePublished - Nov 2003
Externally publishedYes

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Management, Monitoring, Policy and Law

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