Science of The Total Environment
Available online 12 February 2016
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Isabel Camposa, b, , ,

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doi:10.1016/j.scitotenv.2016.01.190
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Highlights

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Wildfire can contribute to the increase of major and trace elements in soils.
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Major and trace elements decreased in soil and ashes with time-since-fire.
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Ashes were enriched in major and trace elements relatively to burnt soils.
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Wildfire promotes the mobilization of major and trace elements in the environment.

Abstract

Wildfires can play an important role in the environmental distribution of major and trace elements, including through their mobilization by fire-induced runoff and associated transport of soil and ash particles. In particular, fire-induced inputs of these elements into the environment are relevant due to their toxicity and environmental persistence. This study aimed to evaluate the role of wildfire and time-since-fire on the redistribution of major and trace elements, which is a topic poorly documented. To this end, levels of V, Mn, Co, Ni, Cu, Cd and Pb were assessed in soil and ash samples collected immediately following a wildfire in north-central Portugal as well as 4 (after the first post-fire rainfall events), 8 and 15 months later. The role of forest type was determined by sampling burnt eucalypt and pine plantations. The main findings of this study were the following: (1) levels of V, Mn, Ni, Cd and Pb were consistently higher in the burnt than unburnt soils, while levels of Co and Cu revealed no differences; (2) time-since-fire affected major and trace elements in three different ways: concentrations of Mn and Cd declined abruptly after the first rainfall events while levels of V, Co and Ni increased during the first 8 months and levels of Cu and Pb hardly changed during the study period; (3) all studied elements revealed peak concentrations in the ashes immediately after the fire, which then declined sharply four months later; (4) levels of Co and Ni soils and ashes were higher at the pine plantations than at the eucalypt plantations. This study highlighted the role of wildfire in enhancing levels of major and trace elements in ashes and topsoil of forest plantations and their mobilization within the first year after fire, pointing towards recently burnt forest areas as a potential source of environmental contamination.

Graphical abstract


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Keywords

  • Forest fire;
  • Topsoil;
  • Time-since-fire;
  • Mobilization
Corresponding author at: Department of Environment and CESAM, University of Aveiro, 3810-193, Aveiro, Portugal.
© 2016 Elsevier B.V. All rights reserved.