Collaborative Proposal: Response of mercury cycling to disturbance and restoration of low-gradient forested watersheds

合作提案：汞循环对低梯度森林流域干扰和恢复的响应

• 批准号: 1851683
• 负责人: James Coleman
• 金额: $ 16.47万
• 依托单位: University of North Carolina Greensboro
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1851683&HistoricalAwards=false
• 关键词: Collaborative; Proposal; Response; mercury; cycling

Environmental pollution of mercury is a global concern. Due to foliar uptake of atmospheric mercury, forested ecosystem represents an important receptor of mercury pollution, while low-gradient forest watersheds in the southeastern United States represent hotspots for production of highly toxic methylmercury that poses a risk to humans and wildlife through consumption of fish and other high trophic level food sources. Throughout the southeastern region, there is an initiative to restore the native longleaf pine over the existing loblolly pine. The proposed research will examine how forest restoration affects various mercury cycling processes in southeastern coastal plain forests. This work will lead to an enhanced understanding of how forest restoration can affect the retention of mercury within watersheds and the production of toxic methylmercury. The proposed work will provide unique training opportunities for undergraduate and graduate students of diverse academic backgrounds from the University of North Carolina at Greensboro (UNCG), a minority serving institution, the University of Michigan (U-M), and the Clemson University. Also, home-schooled students in the coastal region of South Carolina will be involved in the sample collection and processing in order to provide a more formal STEM training to these groups of children lacking resources. The principal investigators will integrate this research into teaching materials of existing classes, including field visits and case studies, and also carry out outreach to professional foresters to inform them about how forestry practices may alter mercury cycling. The work will be widely disseminated through seminars, conference presentations, and peer-reviewed publications. The project proposes to use stable mercury isotopes as an integrative tool to better understand the effects of short-term forest disturbance (prescribed fires, thinning, and clear cut) and longer-term forest restoration (switching back to native tree species with lower water demand) on mercury cycling in a low-gradient coastal forested watershed in South Carolina, where mercury methylation is extensive in poorly drained soils. The project will take place in a paired watershed at Santee Experimental Forest, a typical coastal plain forest headwater watershed. Specifically, the project will use stable mercury isotope ratios to monitor depositional pathways of mercury into the experimental forested watershed and also to distinguish the depositional pathways of mercury exported by the streams. Further, methylmercury isotopes measured in terrestrial and aquatic food web components will provide insights into methylmercury formation and degradation pathways during and after forest manipulation in the experimental watershed. Thus, the proposed work will provide a unique chance to test the utility of stable mercury isotopes for tracking atmospheric mercury deposition and mercury methylation and for following uptake of mercury from different sources into the food webs of both experimental and reference watersheds. Further, microcosm studies will be conducted in order to disentangle different environmental factors and their effects on mercury methylation in these forest soils. Through answering these interrelated questions, the proposed work will be able to reveal the effects of forest management on mercury deposition and methylmercury production in a forested ecosystem in the southeastern region of North America.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.

汞对环境污染是全球关注的问题。由于大气汞的叶面吸收，森林生态系统代表了汞污染的重要受体，而美国东南部的低梯度森林流域代表着生产高毒的甲基汞的热点，它会给人类和野生动植物带来风险，通过消费鱼类和其他高滋养水平的食物来对人类和野生动物产生风险。在整个东南地区，都有一项倡议，可以在现有的Loblolly Pine上恢复本地的Longeaf Pine。拟议的研究将研究森林恢复如何影响东南沿海平原森林的各种汞自行车过程。这项工作将使人们对森林恢复如何影响流域内汞的保留以及有毒甲基压的产生有了增强的了解。拟议的工作将为来自北卡罗来纳大学格林斯伯勒大学（UNCG），少数派服务机构，密歇根大学（U-M）和克莱姆森大学的大学学术背景提供独特的培训机会。此外，南卡罗来纳州沿海地区的家庭教育学生将参与样本收集和处理，以便为缺乏资源的这些儿童组提供更正式的STEM培训。首席研究人员将将这项研究纳入现有班级的教材，包括现场访问和案例研究，并向专业森林人进行宣传，以告知他们林业实践如何改变汞循环。这项工作将通过研讨会，会议演讲和同行评审的出版物广泛传播。该项目建议使用稳定的汞同位素作为一种综合工具，以更好地了解短期森林干扰（处方大火，稀疏和清切的稀疏）和长期森林修复（切换到水需求较低的本地树种）对低层沿海森林水中河水中汞的汞中汞的汞循环的影响，在铜矿中，汞甲基化的含量不高，在泥土中销毁了众多的甲基化甲基化。该项目将在Santee实验森林的配对流域中进行，这是一个典型的沿海平原森林源头水域。具体而言，该项目将使用稳定的汞同位素比监测汞的沉积途径到实验性的森林流域，并区分流媒体导出的汞的沉积途径。此外，在陆生和水生食物网中测量的甲基质方同位素将在实验水域中森林操纵期间和之后提供有关甲基压形成和降解途径的见解。因此，拟议的工作将为测试稳定的汞同位素的实用性，以跟踪大气汞沉积和汞甲基化的实用性，并跟随从不同来源摄入从不同来源进入实验和参考流域的食物网。此外，将进行缩影研究，以消除不同环境因素及其对这些森林土壤中汞甲基化的影响。通过回答这些相互关联的问题，拟议的工作将能够在北美东南部地区的森林生态系统中揭示森林管理对汞沉积和甲基汞生产的影响。该奖项反映了NSF的法定任务，并认为通过基金会的智力功能和广泛的影响来评估Criteria的智力功能和广泛影响。