Peat fires and legacy toxic metal release: An integrative biogeochemical and ecohydrological conceptual framework

IF 10.8 1区 地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY
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引用次数: 0

Abstract

Peatlands are potent landscape sinks of natural and industrial toxic metals and metalloids (TMMs) but the long-term sequestration of TMMs in peatlands is at increasing risk due to climate change enhanced peatland fires. The ability of peatlands to retain TMMs results from a host of interacting hydrological, biological, geomorphological, and chemical feedbacks, which underpin peatland functionality in general. Fire is a transformative force that often disrupts these interactions and feedbacks, leading to the potential release of TMMs to our air, land, and water. Given that wildfire burned area and severity are increasing there is a need for a conceptual understanding of these interactive processes. Prior to a fire, peatland TMM mobility is relatively low, controlled by a peatland's degree of minerotrophy, degradation status, hydrogeomorphic setting and hydroclimate. Incidentally, these peatland characteristics also control the likelihood of peat ignition, creating important feedbacks on the landscape. Following ignition, the temperature and duration of a peat fire plays a critical role in determining the potential TMM emissions to the atmosphere and the post-fire geochemical conditions. We elucidate the varied emission factors of different metals, where emission factors range from 0.2 (Co or Cd) to 300 (Al) mg of metal per kg of particulate matter emitted depending on the specific metal and likely the pre-fire peat metal concentration. Following a peat fire, the geochemical and hydrological changes become increasingly important. For example, post-fire increases in pH play the strongest chemical role in limiting TMM mobilization but concurrent increases in dissolved organic matter aromaticity complicate our understanding of these processes, leading to a critical knowledge gap. At larger spatial scales, peatland and watershed ecohydrological connectivity and peat erosion modulate the release of TMMs to aquatic systems. Yet, the evolution of the ecohydrological connectivity and peat erosion potential as the peatland vegetation and hydrology recover to pre-fire conditions over the course of several to tens of years is governed by the same controls that impact pre-fire TMM mobility. Critically, the uncertainty in evolution trajectories depends on changes in biological, hydrological, climatological, and chemical conditions, limiting our ability to accurately predict these changes under a rapidly changing climate. This extensive and interdisciplinary review guides the development of a conceptual framework and highlights future research needs to better respond to the emerging threat of legacy TMM release from peatland wildfires.

泥炭大火与遗留的有毒金属释放:综合生物地球化学和生态水文概念框架
泥炭地是天然和工业有毒金属和类金属(TMMs)的强大景观汇,但由于气候变化加剧了泥炭地火灾,泥炭地长期固存 TMMs 的风险越来越大。泥炭地保留有毒金属和金属化合物的能力源于一系列相互作用的水文、生物、地貌和化学反馈,这些反馈是泥炭地总体功能的基础。火灾是一种变革性力量,往往会破坏这些相互作用和反馈,导致 TMMs 可能释放到我们的空气、土地和水中。鉴于野火焚烧面积和严重程度不断增加,我们需要从概念上了解这些互动过程。火灾发生前,泥炭地 TMM 的流动性相对较低,受泥炭地的矿化程度、退化状况、水文地质环境和水文气候的控制。顺便提一下,这些泥炭地特征也控制着泥炭点火的可能性,从而对地貌产生重要的反馈作用。点火后,泥炭火的温度和持续时间在决定向大气中的潜在 TMM 排放量和火后地球化学条件方面起着至关重要的作用。我们阐明了不同金属的不同排放因子,其中排放因子范围从每公斤颗粒物排放 0.2(钴或镉)到 300(铝)毫克金属不等,这取决于特定金属以及泥炭燃烧前的金属浓度。泥炭火灾后,地球化学和水文变化变得越来越重要。例如,火灾后 pH 值的增加在限制 TMM 迁移方面发挥了最重要的化学作用,但同时溶解有机物芳香度的增加使我们对这些过程的理解变得更加复杂,从而导致了一个关键的知识缺口。在更大的空间尺度上,泥炭地和流域的生态水文连通性以及泥炭侵蚀会调节 TMM 向水生系统的释放。然而,随着泥炭地植被和水文在数年至数十年间恢复到火灾前的状态,生态水文连通性和泥炭侵蚀潜力的演变也受到影响火灾前 TMM 移动性的相同控制因素的制约。重要的是,演变轨迹的不确定性取决于生物、水文、气候和化学条件的变化,这限制了我们在快速变化的气候条件下准确预测这些变化的能力。这篇广泛的跨学科综述为制定概念框架提供了指导,并强调了未来的研究需求,以更好地应对泥炭地野火释放遗留 TMM 的新威胁。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Earth-Science Reviews
Earth-Science Reviews 地学-地球科学综合
CiteScore
21.70
自引率
5.80%
发文量
294
审稿时长
15.1 weeks
期刊介绍: Covering a much wider field than the usual specialist journals, Earth Science Reviews publishes review articles dealing with all aspects of Earth Sciences, and is an important vehicle for allowing readers to see their particular interest related to the Earth Sciences as a whole.
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