Collaborative Research: RAPID: Do large recent wildfires in the Yukon River Delta alter the delivery of black carbon to the Arctic Ocean?

野火产生木炭，也被称为黑碳，这是耐分解，是环境寿命长。一部分这种烧焦的物质在与水相互作用时溶解，并作为溶解的黑碳（DBC）从土壤中被带到河流中。气候变暖和干燥导致北极地区野火活动增加，目前尚不清楚这些变化将如何影响河流中的DBC数量及其在沿海环境中的命运。2022年夏天，Apoon Pass和East Fork大火烧毁了育空地区三角洲（美国阿拉斯加州）25.5万英亩的土地，这是近年来三角洲野火规模更大、更频繁的趋势的一部分。该项目的主要目标是确定三角洲最近的野火活动是否会导致沿着育空地区河和河口到北冰洋沿岸的DBC数量增加。这项工作的结果将为今后在脆弱的北极流域开展大规模的火源碳研究奠定基础。该项目将支持两名早期职业研究人员和一名研究生在经验丰富的北极调查员的指导下进行合作。野火（木炭生产，土壤不稳定，水文流动路径的变化）对北极主要河流碳输出的累积影响目前尚不清楚。该项目将确定育空地区河流三角洲内最近发生的大规模野火是否改变了育空地区河流-北冰洋连续体沿着的DBC分布、组成和总出口量。为了实现这一目标，将在2023年春季采集新样本，并将结果与2019年存档的新鲜样本进行比较。我们将采用分子标记，稳定碳同位素和高分辨率质谱技术的组合，以评估野火-DBC关系在育空地区河三角洲之间的低火（2019年;约10，000英亩烧毁）和大火（2023年; 255，000英亩烧毁）年。这项工作建立在预测气候变化对北极碳循环影响的其他努力的基础上，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查进行评估来支持的搜索.

Wildfires produce charcoal, also termed black carbon, which is resistant to breakdown and is environmentally long-lived. A portion of this charred material is dissolved upon interaction with water and is carried away from soils to rivers as dissolved black carbon (DBC). A warmer and drier climate has led to increased wildfire activity in Arctic regions and it is unknown how these changes will affect the amount of DBC in rivers and its fate in the coastal environment. In the summer of 2022, the Apoon Pass and East Fork Fires burned 255,000 acres in the Yukon River Delta (Alaska, USA), part of a trend towards larger and more frequent wildfires in the Delta in recent years. The main goal of this project is to determine whether recent wildfire activity in the Delta leads to increased amounts of DBC along the Yukon River and estuary to the coastal Arctic Ocean. Results of this work will lay the groundwork for future, large-scale studies on fire-derived carbon in vulnerable Arctic watersheds. This project will support collaboration among two early career researchers and one graduate student with guidance from an experienced Arctic investigator.Pan-Arctic watersheds are experiencing increased fire activity as a result of climate change. The cumulative effects of wildfire (charcoal production, soil destabilization, change in hydrologic flow paths) on carbon export in major Arctic rivers is currently unknown. This project will determine whether large, recent wildfires within the Yukon River Delta have changed the distribution, composition, and total export of DBC along the Yukon River-to-Arctic Ocean continuum. To achieve this goal, new samples will be collected during the 2023 spring freshet and results compared to those obtained from archived 2019 freshet samples. We will employ a combination of molecular marker, stable carbon isotope, and ultrahigh resolution mass spectral techniques to evaluate wildfire-DBC relationships in the Yukon River Delta between low-fire (2019; ~10,000 acres burned) and high-fire (2023; 255,000 acres burned) years. This work builds upon other efforts to predict the effects of climate change on carbon cycling in Arctic-boreal landscapes and will assist in answering broad research questions regarding the behavior of DBC in intermediate reservoirs and fate of terrestrial organic matter in the coastal ocean.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.