Tshering Kuenzang, Miotlinski Konrad, Blake David, Boyce Mary C, Bath Andrew, Carvalho Ana, Horwitz Pierre
School of Science, Edith Cowan University, 270 Joondalup Drive, Perth, Australia; Centre for People, Place and Planet, Edith Cowan University, 270 Joondalup Drive, Perth, Australia.
School of Science, Edith Cowan University, 270 Joondalup Drive, Perth, Australia.
Water Res. 2023 Feb 15;230:119490. doi: 10.1016/j.watres.2022.119490. Epub 2022 Dec 14.
Fires in forested catchments pose a water contamination risk from fire-derived dissolved organic matter (DOM). Fire events are expected to increase under a projection of warmer and drier climatic conditions; therefore, understanding the consequences of fire-derived DOM is critical for water supply and management of drinking water and catchments. This paper addresses how fire regime - the intensity, severity and frequency of fires - influences DOM quantity and composition in surface waters in forested catchments, and how long it takes for water quality to recover to pre-fire levels. A review of post-fire studies in Mediterranean regions reporting on DOM related parameters has been conducted. The literature shows that post-fire DOM composition and reactivity is different from DOM generated under processes of biological degradation, and hence our reliance on DOM 'bulk properties' and surrogate DOM bulk parameters may not provide sufficient information to deal with the potential complexity of the organic compounds produced by a catchment fire. Appropriate measures are important to adequately operate conventional water treatment facilities, for example. Critical parameters for the effects of burning include the alteration of DOM composition, aromaticity, and the relative amounts of labile/recalcitrant organic components. The literature shows mixed information for the influence of both burn severity and fire intensity, on these parameters, which indicates DOM response to fire is highly variable. For fire frequency, the evidence is more unequivocal, indicating that frequent fires change the composition of DOM to components that are less bioavailable, and elevate the degree of aromaticity, which may be detrimental to water quality. In addition, and in general terms, the more recent the fire, the more aromatic and humified DOM components are found, and vice versa. The recovery of surface water quality to pre-fire conditions was variable, with no safe temporal thresholds suggested in the literature. In some cases, fire-induced changes in DOM composition were observable up to 16 years post-fire. The lack of clearly observed trends in post-fire DOM with fire regimes could be attributed to numerous factors such as limited long-term and event-based observations, experimental design challenges, and site-specific biological, physical and hydrological factors. The application of terminologies used to describe fire regimes such as burn severity and fire intensity also creates challenges in comparing the outcomes and results from numerous studies.
森林集水区的火灾会因火灾产生的溶解有机物（DOM）带来水污染风险。在气候变暖和干燥的预测情况下，火灾事件预计会增加；因此，了解火灾产生的DOM的后果对于饮用水供应以及饮用水和集水区的管理至关重要。本文探讨了火灾 regime（火灾的强度、严重程度和频率）如何影响森林集水区地表水的DOM数量和组成，以及水质恢复到火灾前水平需要多长时间。对地中海地区报告DOM相关参数的火灾后研究进行了综述。文献表明，火灾后DOM的组成和反应性与生物降解过程中产生的DOM不同，因此我们对DOM“总体性质”和替代DOM总体参数的依赖可能无法提供足够信息来应对集水区火灾产生的有机化合物的潜在复杂性。例如，采取适当措施对于常规水处理设施的充分运行很重要。燃烧影响的关键参数包括DOM组成的改变、芳香性以及不稳定/难降解有机成分的相对含量。文献显示，关于燃烧严重程度和火灾强度对这些参数的影响的信息不一，这表明DOM对火灾的反应高度可变。对于火灾频率，证据更为明确，表明频繁火灾会将DOM的组成改变为生物可利用性较低的成分，并提高芳香度，这可能对水质有害。此外，一般来说，火灾发生的时间越近，发现的芳香化和腐殖化DOM成分就越多，反之亦然。地表水水质恢复到火灾前状况的情况各不相同，文献中未提出安全的时间阈值。在某些情况下，火灾后长达16年仍可观察到火灾引起的DOM组成变化。火灾后DOM随火灾 regime缺乏明确观察到的趋势可能归因于众多因素，如长期和基于事件的观测有限、实验设计挑战以及特定地点的生物、物理和水文因素。用于描述火灾 regime的术语（如燃烧严重程度和火灾强度）的应用也给比较众多研究的结果带来了挑战。
