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

知识价值：pi建议量化麦克默多干谷泰勒谷的山坡水、溶质和碳预算，使用水轨调查近地表地质过程，挑战浅层地下水极少或不存在的范式。水道是高土壤水分的线性带，在永久冻土占主导地位的土壤中引导浅层地下水下坡。本文将测试四个假设：1)水道是水和溶质运输的重要途径；2)泰勒河谷的水道比河流输送更多的溶解二氧化硅，表明它们是冷沙漠土壤和基岩化学风化的主要场所；③高原水系以隔湿盐水为主，低地水系以海洋气溶胶为主；4)水道是Taylor Valley陆相土壤碳浓度最高和CO2通量最强的场所，其碳含量随土壤年龄的增长而增加，而碳通量则随土壤年龄的增长而减少。为了验证这些假设，pi将在建模和遥感的支持下进行一套实地测量。他们将在泰勒谷的各种地质、气候和地形条件的水轨上安装浅层永久冻土井。多频电磁感应测深的上部~1米的永久冻土带将创建第一个全面的土壤湿度图在泰勒山谷，并将允许直接量化水的轨道流量横跨山谷。将测量水路土壤的碳含量，并将其与全球碳动态联系起来。更广泛的影响：俄勒冈州立大学的非科学专业学生将通过一门新的全球环境变化课程纳入拟议的研究，该课程侧重于南极洲的科学方法。代表人数不足的少数民族的三名本科生将参与研究，为实地和实验室科学的所有方面作出贡献，并将在国家会议上介绍结果。

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.