Cryptic Hydrology of the McMurdo Dry Valleys: Water Track Contributions to Water and Geochemical Budgets in Taylor Valley, Antarctica

智力优势：PIS建议量化麦克默多干旱河谷泰勒山谷的山坡水、溶质和碳收支，使用水迹来调查近地表地质过程，并挑战浅层地下水极少或不存在的范式。在以冻土为主的土壤中，水径迹是沿浅层地下水向下延伸的高土壤水分的线性区域。将检验四个假设：1)水迹是水和溶质运输的重要途径；2)水迹比泰勒河谷的溪流运输更多的溶解二氧化硅，这表明它们是寒冷沙漠土壤和基岩化学风化的主要场所；3)排水高地的水迹主要是湿度分离的卤水，而排水低地地形的水迹主要是海洋气溶胶；4)水迹是泰勒山谷陆地土壤碳浓度最高和二氧化碳通量最强的地点，其碳含量随着土壤年龄的增加而增加，而碳通量随着年龄的增加而减少。为了验证这些假设，PIS将进行一套由建模和遥感支持的现场测量。他们将在泰勒谷各种地质、气候和地形条件的水道上安装浅层永久冻土井。对多年冻土上部~1米的多频电磁感应测深将创建泰勒谷第一张全面的土壤水分图，并将允许直接量化跨山谷的径流流量。水轨道土壤的碳含量将被测量并与全球碳动态联系起来。广泛的影响：俄勒冈州立大学的非理科专业的学生将通过一门新的全球环境变化课程纳入拟议的研究，课程重点是南极洲的科学方法。三名本科生，代表人数不足的少数民族，将参与这项研究，将对实地和实验室科学的各个方面做出贡献，并将在全国会议上展示成果。

Intellectual Merit: The PIs propose to quantify the hillslope water, solute, and carbon budgets for Taylor Valley in the McMurdo Dry Valleys, using water tracks to investigate near-surface geological processes and challenge the paradigm that shallow groundwater is minimal or non-exixtant. Water tracks are linear zones of high soil moisture that route shallow groundwater downslope in permafrost dominated soils. Four hypotheses will be tested: 1) water tracks are important pathways for water and solute transport; 2) water tracks transport more dissolved silica than streams in Taylor Valley indicating they are the primary site of chemical weathering for cold desert soils and bedrock; 3) water tracks that drain highland terrains are dominated by humidity-separated brines while water tracks that drain lowland terrains are dominated by marine aerosols; 4) water tracks are the sites of the highest terrestrial soil carbon concentrations and the strongest CO2 fluxes in Taylor Valley and their carbon content increases with soil age, while carbon flux decreases with age. To test these hypotheses the PIs will carry out a suite of field measurements supported by modeling and remote sensing. They will install shallow permafrost wells in water tracks that span the range of geological, climatological, and topographic conditions in Taylor Valley. Multifrequency electromagnetic induction sounding of the upper ~1 m of the permafrost will create the first comprehensive map of soil moisture in Taylor Valley, and will permit direct quantification of water track discharge across the valley. The carbon contents of water track soils will be measured and linked to global carbon dynamics.Broader impacts: Non-science majors at Oregon State University will be integrated into the proposed research through a new Global Environmental Change course focusing on the scientific method in Antarctica. Three undergraduate students, members of underrepresented minorities, will be entrained in the research, will contribute to all aspects of field and laboratory science, and will present results at national meetings.