CAREER: Quantifying the Extent and Biogeochemical Impact of Modern Ferruginous Lakes

职业：量化现代含铁湖泊的范围和生物地球化学影响

• 批准号: 1944946
• 负责人: Elizabeth Swanner
• 金额: $ 66.25万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1944946&HistoricalAwards=false
• 关键词: CAREER; Quantifying; Extent; Biogeochemical; Impact

Many small, deep lakes formed during the melting of continental ice sheets that covered much of the northern hemisphere before 10,000 years ago. It is hard for oxygen to mix into small, deep lakes, which makes them “microbial worlds”, as most aquatic animals can’t live without oxygen. This project will test whether such small lakes that lack oxygen also contain abundant iron, and whether that iron is supplied from the surrounding glacial deposits. With no oxygen, and abundant iron, lake microbes can produce methane out of sinking algal or plant material. Road salt applications near lakes might also cause lakes that did mix to stop mixing, making conditions better for methane-producing microbes. This work will give a better idea how lake shape, microbes, and water chemistry contribute to lake emissions of methane, which is an important but not well-understood contributor to natural greenhouse gas emissions to the atmosphere. The chemistry of these lakes is also similar to the oceans before 500 million years ago, before animals appeared, and so we can use them to help understand if oceans were producing methane in the past. Undergraduate and graduate students will collect field data from lakes in a rural and urban area in Minnesota (MN) as part of class and research expeditions. The field methods, findings, and data will be shared through traditional (publications and conferences) and non-traditional (YouTube videos, Wikipedia pages) outlets. Workshops in Minneapolis, MN will engage diverse youth, including residents of a historically African American neighborhood adjacent to an urban study lake. Workshops in Itasca State Park, MN, the site of the rural lakes, will engage the visiting public and residents of surrounding counties and nearby Native American population centers.There are only 22 ferruginous meromictic lakes worldwide identified in the literature, but do more exist? Most of the recognized ferruginous meromictic lakes are postglacial, with groundwater or peatlands a hypothesized, but unverified source of iron. More than a dozen postglacial lakes in two field areas in Minnesota (MN) will be evaluated for meromixis and ferruginous conditions, giving insight into how land use changes enhance meromixis. Detailed iron budgets will be constructed for two lakes to identify and quantify iron sources. Many ferruginous meromictic lakes have a subsurface chlorophyll a maximum layer at the iron-oxygen redoxcline, and the contribution of this layer to primary productivity and oxygen production will be quantified in two lakes. Furthermore, rates of methanogenesis, methane fluxes, and the contribution of methane to the organic carbon degradation will be quantified in two lakes to better constrain carbon fluxes under ferruginous conditions. The results of these activities will better delineate 1) the extent of meromictic ferruginous lakes, 2) fluxes of water and elements between surface and groundwater reservoirs, 3) and carbon cycling under ferruginous conditions, which predominated in Earth's past oceans and influenced the oxidation of Earth's surface.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.

一万年前，覆盖北半球大部分地区的大陆冰盖融化时，形成了许多小而深的湖泊。氧气很难混合到小而深的湖泊中，这使它们成为“微生物世界”，因为大多数水生动物没有氧气就无法生存。这个项目将测试这些缺氧的小湖泊是否也含有丰富的铁，以及这些铁是否来自周围的冰川沉积物。由于没有氧气和丰富的铁，湖泊微生物可以从下沉的藻类或植物材料中产生甲烷。在湖泊附近施用道路盐也可能导致已经混合的湖泊停止混合，为产生甲烷的微生物创造更好的条件。这项工作将更好地了解湖泊形状、微生物和水化学如何影响湖泊甲烷的排放，甲烷是向大气排放天然温室气体的重要因素，但尚未得到充分了解。这些湖泊的化学成分也与5亿年前动物出现之前的海洋相似，因此我们可以利用它们来帮助了解海洋过去是否产生甲烷。本科生和研究生将从明尼苏达州农村和城市地区的湖泊收集实地数据，作为课堂和研究探险的一部分。实地研究方法、发现和数据将通过传统的（出版物和会议）和非传统的（YouTube视频、维基百科页面）渠道进行共享。在明尼苏达州明尼阿波利斯市举办的研讨会将吸引不同的年轻人，其中包括毗邻城市学习湖的历史上非裔美国人社区的居民。在明尼苏达州的伊塔斯卡州立公园（乡村湖泊所在地）举办的讲习班将吸引来访的公众、周边县的居民和附近的美洲原住民人口中心。在世界范围内，文献中只发现了22个含铁的分生湖泊，但是否存在更多的湖泊？大多数已知的含铁分生湖泊是冰川后形成的，地下水或泥炭地是一种假设的铁来源，但未经证实。将对明尼苏达州（MN）两个野外地区的十多个冰期后湖泊进行溶质混合和含铁条件的评估，从而深入了解土地利用变化如何增强溶质混合。将为两个湖泊建立详细的铁预算，以确定和量化铁来源。许多含铁分生湖泊在铁氧氧化还原层处有一个次表层叶绿素a最大层，这一层对初级生产力和氧气生产的贡献将在两个湖泊中进行量化。此外，将量化两个湖泊的甲烷生成速率、甲烷通量以及甲烷对有机碳降解的贡献，以更好地约束含铁条件下的碳通量。这些活动的结果将更好地描述1)分生含铁湖泊的范围，2)地表水和地下水水库之间的水和元素通量，3)含铁条件下的碳循环，这在地球过去的海洋中占主导地位，并影响了地球表面的氧化。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。

项目成果

Evaluation of preservation protocols for oxygen‐sensitive minerals within laminated aquatic sediments

层状水生沉积物中氧敏感矿物的保存方案评估

• DOI: 10.1002/lom3.10533
• 发表时间: 2023
• 期刊: Limnology and Oceanography: Methods
• 作者: Ledesma, Gabrielle;Islam, Raisa;Swanner, Elizabeth D.
• 通讯作者: Swanner, Elizabeth D.

Methane-derived authigenic carbonates – A case for a globally relevant marine carbonate factory

• DOI: 10.1016/j.earscirev.2023.104487
• 发表时间: 2023-08
• 期刊: Earth-Science Reviews
• 影响因子: 12.1
• 作者: Sajjad Akam;E. Swanner;H. Yao;W. Hong;Jörn Peckmann

Water properties of Arco Lake, Budd Lake, Deming Lake, and Josephine Lake in Itasca State Park from 2006-2009 and 2019-2021, v. 2.

2006-2009 年和 2019-2021 年艾塔斯卡州立公园阿科湖、巴德湖、戴明湖和约瑟芬湖的水特性，v. 2。

• DOI: 10.6073/pasta/692c92ef1c8291162732c2b98cebdaea
• 发表时间: 2022
• 期刊: Environmental Data Initiative
• 作者: Swanner, Elizabeth D;Lascu, Ioan;Ledesma, Gabrielle;Leung, Tania;Akam, Sajjad
• 通讯作者: Akam, Sajjad

Geochemical data from sediments and porewaters from ferruginous and meromictic Brownie Lake, Minnesota, U.S.A.

来自美国明尼苏达州铁质和半重质布朗尼湖沉积物和孔隙水的地球化学数据

• DOI: 10.6073/pasta/68b50baa0a767ab33f2b7dd91948036e
• 发表时间: 2022
• 期刊: Environmental Data Initiative
• 作者: Swanner, Elizabeth D.;Islam, Raisa;Ledesma, Gabrielle;Wittkop, Chad;Akam, Sajjad;Eitel, Eryn;Katsev, Sergei;Johnson, Ben;Poulton, Simon;Bray, Andy
• 通讯作者: Bray, Andy

Water properties of Brownie Lake, MN and Canyon Lake, MI from 2015-2019

2015-2019 年明尼苏达州布朗尼湖和密歇根州峡谷湖的水特性

• DOI: 10.6073/pasta/4eaf698b4efbaf793b83d95f464d1672
• 发表时间: 2021
• 期刊: Environmental Data Initiative
• 作者: Swanner, Elizabeth D;Lambrecht, Nicholas;Wittkop, Chad;Katsev, Sergei;Ledesma, Gabrielle;Leung, Tania
• 通讯作者: Leung, Tania