Spatial and Temporal Shifts in Dissolved Organic Matter Character Across a Burned Stream Network

IF 3.7 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES
K. A. Wampler, K. D. Bladon, A. N. Myers-Pigg, J. A. Roebuck Jr.
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Abstract

Increasing wildfire activity can impact the global carbon cycle, aquatic ecosystem health, and drinking water treatment through alterations in aquatic dissolved organic matter (DOM) composition. However, uncertainty remains about the spatial and temporal variability in wildfire effects on DOM composition. We sought to improve understanding of how burn severity affects stream DOM and how weather, hydrology, and landscape factors contribute to variability in post-fire DOM responses across space and time. Following a large 2020 wildfire in Oregon, USA, we collected water samples to quantify dissolved organic carbon and DOM optical properties at 129 stream sites across the fire-affected stream network. Sampling was repeated across seasonal hydrologic conditions to capture variation in hydrologic pathways and organic matter sources. We developed a PARAFAC model using excitation-emission matrices (EEMs) and used spatial stream network (SSN) models to determine how DOM composition changed across the stream network with burn severity. The greatest shifts in DOM composition were observed during the dry and wetting seasons, with an increase in aromatic DOM at higher burn severities. In contrast, an increase in protein-like DOM was observed during the wet season at higher burn severities. Drainage area, 31-day and 1-day antecedent precipitation, and baseflow index impacted the relationship between DOM composition and burn severity, which could partially explain the variability in post-fire DOM responses. Our study contributes a mechanistic understanding of how wildfire impacts DOM sources and composition, which is critical to predicting wildfire effects on aquatic biogeochemical cycling and preserving ecosystem health and source water quality.

Abstract Image

燃烧水系中溶解有机质特征的时空变化
野火活动的增加可以通过改变水生溶解有机质(DOM)组成影响全球碳循环、水生生态系统健康和饮用水处理。然而,野火对DOM组成影响的时空变异性仍存在不确定性。我们试图提高对烧伤严重程度如何影响河流DOM的理解,以及天气、水文和景观因素如何影响火灾后DOM响应的时空变化。在2020年美国俄勒冈州发生大规模野火之后,我们收集了水样,以量化受火灾影响的河流网络中129个河流站点的溶解有机碳和DOM光学性质。在不同的季节水文条件下重复采样,以捕捉水文路径和有机物来源的变化。我们使用激发发射矩阵(EEMs)开发了一个PARAFAC模型,并使用空间流网络(SSN)模型来确定DOM组成如何随烧伤严重程度在流网络中变化。DOM组成变化最大的季节是干湿季节,燃烧程度越高,芳香DOM含量越高。相比之下,在烧伤严重程度较高的雨季,观察到蛋白质样DOM的增加。流域面积、前31天和前1天降水量以及基流指数影响了DOM组成与烧伤严重程度的关系,这可以部分解释火灾后DOM响应的变异性。我们的研究有助于了解野火对DOM来源和组成的影响机制,这对于预测野火对水生生物地球化学循环的影响以及保护生态系统健康和水源水质至关重要。
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来源期刊
Journal of Geophysical Research: Biogeosciences
Journal of Geophysical Research: Biogeosciences Earth and Planetary Sciences-Paleontology
CiteScore
6.60
自引率
5.40%
发文量
242
期刊介绍: JGR-Biogeosciences focuses on biogeosciences of the Earth system in the past, present, and future and the extension of this research to planetary studies. The emerging field of biogeosciences spans the intellectual interface between biology and the geosciences and attempts to understand the functions of the Earth system across multiple spatial and temporal scales. Studies in biogeosciences may use multiple lines of evidence drawn from diverse fields to gain a holistic understanding of terrestrial, freshwater, and marine ecosystems and extreme environments. Specific topics within the scope of the section include process-based theoretical, experimental, and field studies of biogeochemistry, biogeophysics, atmosphere-, land-, and ocean-ecosystem interactions, biomineralization, life in extreme environments, astrobiology, microbial processes, geomicrobiology, and evolutionary geobiology
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