EAR-PF: Nitrogen processing in Arctic deltas and role of channel network orientation on flux to the coast

EAR-PF：北极三角洲的氮处理以及河道网络方向对海岸通量的作用

• 批准号: 1952914
• 负责人: Deon Knights
• 金额: $ 17.4万
• 依托单位: Knights, Deon H
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1952914&HistoricalAwards=false
• 关键词: EAR; PF; Nitrogen; processing; Arctic

An EAR Postdoctoral Fellowship has been awarded to Dr. Deon Knights to work at West Virginia University to undertake research and educational activities. The research will examine how deltas control the flux of terrestrially derived nitrate to the Arctic Ocean, which contains only 1% of global ocean volume but receives 10% of global river discharge. Consequently, the Arctic Ocean is sensitive to high riverine flux of particulates and nutrients, with implications on global carbon cycling, marine biogeochemistry, and fishery health. Although Arctic deltas may alter the nutrient composition of river water discharging to the ocean, almost all discharge and nutrient data for Arctic rivers are based on measurements upstream of deltas, so the extent to which Arctic deltas alter nutrient fluxes to the ocean remains largely unexplored. Through field measurements, laboratory analyses, and modeling efforts, this research will investigate the capacity of Arctic deltas to remove nitrate that would otherwise discharge to the Arctic Ocean. Findings will give insight into the response of nutrient processing in Arctic deltas in response to potential scenarios of climate change which may be used to improve global climate ocean and atmospheric models. This project relies on new field and remote sensing techniques which will be used as a teaching tool for laboratory and field-based courses at West Virginia University at the undergraduate and graduate level. With assistance from project mentor Professor Christopher Russoniello, Dr. Deon Knights will lead seminars through service organizations at West Virginia University aimed at mentoring and supporting underrepresented students in STEM fields.This proposal aims to use a multi-scale approach to investigate how the morphology of channel networks within Arctic deltas influences nitrate retention and transport under current and future climate scenarios. Three main objectives will be met: (1) measure how the percent nitrate removal within delta channels varies as a function of channel size, (2) quantitatively relate nitrate retention in large Arctic deltas to structural differences between deltas to inform the potential of different Arctic delta types to act as nitrate removal hotspots and (3) explore and compare nitrate retention under future climatic scenarios in the six Arctic Great River deltas. The relationship between stream size and nitrate removal will inform the removal kinetics necessary for upscaling to network-wide models. Morphologic and hydrologic models of the six largest Arctic deltas will be developed based on remotely-sensed surface water observations and delta morphometrics will be used to compare nitrate retention between deltas of differing structures. Except for insight from a few studies, nitrate processing downstream of delta apexes and upstream of the coast are virtually unknown. This study provides a necessary step to understanding nitrate removal across vast remote areas of the Arctic by using remotely-sensed surface water observations coupled with removal kinetics. This project received co-funding from the Hydrologic Science program in the Division of Earth Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).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.

Deon Knights博士被授予博士后奖学金，在西弗吉尼亚大学从事研究和教育活动。该研究将研究三角洲如何控制陆地来源的硝酸盐流入北冰洋，北冰洋仅占全球海洋体积的1%，但接收全球河流排放量的10%。因此，北冰洋是敏感的高河流通量的颗粒物和营养物质，对全球碳循环，海洋生物地球化学和渔业健康的影响。虽然北极三角洲可能会改变排入海洋的河水的营养成分，但几乎所有北极河流的排放和营养数据都是基于三角洲上游的测量，因此北极三角洲改变海洋营养通量的程度在很大程度上尚未探索。通过实地测量，实验室分析和建模工作，这项研究将调查北极三角洲的能力，以消除硝酸盐，否则将排放到北冰洋。研究结果将深入了解北极三角洲的营养加工响应气候变化的潜在情景，可用于改善全球气候，海洋和大气模型。该项目依赖于新的实地和遥感技术，这些技术将用作西弗吉尼亚大学本科生和研究生实验室和实地课程的教学工具。在项目导师Christopher Russoniello教授的帮助下，Deon Knights博士将通过西弗吉尼亚大学的服务机构领导研讨会，旨在指导和支持STEM领域代表性不足的学生。该提案旨在使用多尺度方法来研究北极三角洲内通道网络的形态如何影响当前和未来气候情景下硝酸盐的保留和运输。将实现三个主要目标：（1）测量δ通道内的硝酸盐去除百分比如何作为通道尺寸的函数而变化，（2）将大型北极三角洲中的硝酸盐保留与三角洲之间的结构差异定量联系起来，以告知不同北极三角洲类型作为硝酸盐去除热点的潜力，以及（3）探索和比较未来气候情景下的六个北极大河三角洲的硝酸盐保留。流大小和硝酸盐去除之间的关系将通知必要的网络范围内的模型放大的去除动力学。将根据遥感地表水观测结果建立北极六个最大三角洲的形态和水文模型，并将利用三角洲形态测量学比较不同结构三角洲之间的硝酸盐保留情况。除了从少数研究的见解，硝酸盐处理下游三角洲顶点和上游的海岸几乎是未知的。这项研究提供了一个必要的步骤，了解硝酸盐的去除在北极广大偏远地区通过使用遥感地表水观测加上去除动力学。该项目获得了地球科学部水文科学项目和激励竞争性研究既定项目（EPSCoR）的共同资助。该奖项反映了NSF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

Seasonal and Morphological Controls on Nitrate Retention in Arctic Deltas

• DOI: 10.1029/2022gl102201
• 发表时间: 2023-04
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: D. Knights;A. Piliouras;J. Schwenk;J. Hariharan;Christopher J. Russoniello