Oak Ridge Institute for Science and Education (ORISE) Post-doc, c/o U.S. Environmental Protection Agency, Corvallis, OR 97330, USA.
U.S. Environmental Protection Agency, Center for Public Health and Environmental Assessment, Corvallis, OR 97330, USA.
Sci Total Environ. 2023 Mar 10;863:160731. doi: 10.1016/j.scitotenv.2022.160731. Epub 2022 Dec 9.
The use of low-severity prescribed fires has been increasingly promoted to reduce the impacts from high-severity wildfires and maintain ecosystem resilience. However, the effects of prescribed fires on water quality have rarely been evaluated relative to the effects of wildfires. In this study, we assessed the effects of 54 wildfires and 11 prescribed fires on trace element (arsenic, selenium, and cadmium) concentrations of streams draining burned watersheds in the western US. To obtain results independent of the choice of method, we employed three independent analytical approaches to evaluate fire effects on water quality for the first three post-fire years. In general, we observed significant increases in trace element concentrations in streams burned by large, high-severity wildfires, despite substantial variability across sites. Comparatively, we did not observe increases in the spring mean concentration of arsenic, selenium, and cadmium in watersheds burned by prescribed fires. Our analysis indicated that the post-fire trace element response in streams was primarily influenced by burn area, burn severity, post-fire weather, surface lithology, watershed physiography, and land cover. This study's results demonstrate that prescribed burns could lessen the post-fire trace element loads in downstream waters if prescribed fires reduce subsequent high severity fires in the landscape.
低强度计划火烧被越来越多地提倡用于减少高强度野火的影响并维持生态系统的恢复力。然而，相对于野火的影响，计划火烧对水质的影响很少被评估。在这项研究中，我们评估了 54 起野火和 11 起计划火烧对美国西部火烧流域溪流中微量元素（砷、硒和镉）浓度的影响。为了获得独立于方法选择的结果，我们采用了三种独立的分析方法来评估前三个火灾后年度水质的火灾影响。一般来说，尽管各地点之间存在很大的变异性，但我们观察到了由大型高强度野火燃烧的溪流中微量元素浓度的显著增加。相比之下，我们没有观察到由计划火烧燃烧的流域中砷、硒和镉的春均值浓度增加。我们的分析表明，溪流中火灾后微量元素的响应主要受火烧面积、火烧严重度、火灾后天气、地表岩性、流域地貌和土地覆盖的影响。本研究的结果表明，如果计划火烧减少景观中的后续高强度火灾，计划火烧可能会减轻下游水中的火灾后微量元素负荷。
