Collaborative Research: RAPID: Identifying the biogeochemical causes of sudden widespread metal loading in streams of the western Brooks Range, Alaska

国家公园和野生动物保护区保护了阿拉斯加布鲁克斯山脉的大片地区，但却无法保护其荒野免受气候变化的影响。变暖的速度是地球上其他地方的四倍，更高的温度融化了海冰，解冻了永久冻土，甚至增加了冬季降雪。这也促使驼鹿、云杉、海狸和灌木进入冻土带。在所有气候驱动的变化中，最近溪流水质的退化可能是最令人担忧的。长期以来，布鲁克斯山脉以其清澈的海水而闻名。突然变成橙色、浑浊的水令人吃惊，可能威胁到生活在那里的丰富的北极灰鲑、多莉瓦尔登鳟鱼和鲑鱼。目前还没有人知道为什么河流正在发生变化，也没有人知道这对鱼类、野生动物和依赖它们的人们在近期或长期内意味着什么。研究人员是一群在“酸性岩石排水”方面有丰富经验的地质学家，以及具有广泛布鲁克斯山脉知识的生态学家。他们计划在2023年夏天访问一个有许多退化溪流的地区，在野外花费一个半月的时间收集岩石、土壤和水样，用于实验室分析。他们的发现将帮助我们了解现在发生了什么，以及未来会发生什么。在阿拉斯加的北极地区，成千上万的人依靠清澈而富有生产力的溪流来获取饮用水和维持生计的鱼类。那里的人们已经对他们所看到的水质恶化感到震惊。为了分享他们的研究成果，研究人员将在地区中心和最大的人口中心Kotzebue的公开演讲中展示他们的发现。他们将为该地区最大的公共广播电台提供采访，这样周边小村庄的居民就可以了解当地溪流和河流的变化，以及这些变化是如何影响当地生态的。他们还将在西北北极区域生存咨询委员会的会议上发言，直接与区域生存资源管理人员和有关公众分享他们的成果。历史上，布鲁克斯山脉的南部斜坡以原始溪流为特征，为大量的北极灰鲑、多莉瓦尔登和鲑鱼提供了栖息地，为当地社区提供了宝贵的经济和生存资源。然而，自2019年以来，30多条清澈的溪流因铁沉淀而变得浑浊和橙色。在冻土带和高地岩层中发现了渗漏现象。有限的数据显示，地下水的pH值非常低（3.0），下坡植被死亡率高，受影响的水源幼鱼丰度急剧下降。原始溪流迅速退化的原因尚不清楚。该项目的目标是确定陆地生物地球化学过程，导致最近在整个西布鲁克斯山脉广泛扩散的浑浊橙色溪流。通过实地取样和实验室分析，研究人员将检验两种假设，以解释受影响流域内金属的动员。他们的两个假设可能都被证明是相关的，但对河流水质和未来河流退化风险地区的空间范围有不同的含义。通过确定橙流扩散的原因，研究人员将能够告知土地管理者和当地村庄的居民饮用水的潜在后果，生存资源的可用性，以及阿拉斯加西北部现在和未来不断增长的商业鲑鱼渔业。这项关于西部布鲁克斯山脉河流退化原因的研究与该地区的阿拉斯加原住民村庄高度相关，这些村庄依赖这些河流提供饮用水和生存鱼类。由于乌利克河、松鼠河和科布克河附近的支流退化，Kiana和Kivalina村尤其处于危险之中。研究人员将在Kotzebue发表公开演讲，并安排接受Kotzebue公共广播电台的采访，与周围较小村庄的居民分享他们的发现。他们还计划在西北北极地区生存咨询委员会的会议上分享他们的发现，将结果直接传达给地区生存资源管理者和有关公众。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

National Parks and Wildlife Refuges protect a vast area of Alaska’s Brooks Range but cannot shield its wilderness from climate change. Warming four times faster than elsewhere on Earth, the higher temperatures melt sea ice, thaw permafrost, and even increase winter snowfall. This also encourages moose, spruce, beavers, and shrubs to move into tundra. Of all the climate-driven changes, the recent degradation of stream water quality may be most alarming. The Brooks Range has long been known for its crystal-clear waters. The abrupt change to orange-colored, murky waters is startling and likely threatens the abundant Arctic grayling, Dolly Varden trout, and chum salmon that live there. No one currently knows why the streams are changing or what it means in the near or long term for fish, wildlife, and the people who depend upon them. The researchers are a group of geologists with extensive experience in “acid-rock drainage” joined by ecologists with extensive Brooks Range knowledge. They plan to visit an area with numerous degraded streams during the summer of 2023, spending a month and a half in the field collecting rock, soil, and water samples for laboratory analysis. What they find will help us understand what is happening now and what to expect in the future. Thousands of people depend on clear and productive streams for drinking water and subsistence fish harvest in Arctic Alaska. People there are already alarmed about the degradation in water quality they can see. To share what they learn, the researchers will present their findings in public presentations in Kotzebue, the regional hub and largest population center. They will provide interviews for the region’s largest public radio station, so that residents of smaller surrounding villages can learn about the changes to their local streams, regional rivers and how those changes are already impacting local ecologies. They will also speak at meetings of the Northwest Arctic Regional Subsistence Advisory Council to share their results directly with regional managers of subsistence resources and concerned members of the public.Historically characterized by pristine streams that support robust populations of Arctic grayling, Dolly Varden, and chum salmon, the southern slopes of the Brooks Range provide valuable economic and subsistence resources for local communities. However, since 2019, more than 30 clear-running streams have turned turbid and orange with iron precipitates. Seeps have been identified in the tundra and in upland rock formations. Limited data show very low pH in seep water (3.0), downslope vegetation mortality, and dramatic declines in juvenile fish abundance in affected headwaters. The causes of this rapidly spreading degradation of pristine streams remain unknown. The goal of this project is to identify the terrestrial biogeochemical processes causing the recent and widespread proliferation of turbid orange streams throughout the western Brooks Range. Through field sampling and laboratory analysis, the researchers will test two hypotheses to explain the mobilization of metals within affected watersheds. Their two hypotheses, which may both prove relevant, have divergent implications for stream water quality and the spatial extent of areas at risk of future stream degradation. By identifying the causes of orange stream proliferation, the researchers will be able to inform land managers and residents of local villages of the potential consequences for drinking water, subsistence resource availability, and the growing commercial salmon fishery in northwest Alaska now and in the future. This research on the causes of stream degradation in the western Brooks Range is highly relevant to Alaska Native villages in the region, which depend on these streams for drinking water and subsistence fish harvest. The villages of Kiana and Kivalina are especially at risk because of nearby degraded tributaries of the Wulik, Squirrel and Kobuk Rivers. The researchers will deliver public presentations in Kotzebue and arrange to be interviewed by Kotzebue Public Radio to share their findings with residents of smaller surrounding villages. They also plan to share their findings during meetings of the Northwest Arctic Regional Subsistence Advisory Council to communicate their results directly to regional managers of subsistence resources and concerned members of the public.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.