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

智力优势：PI建议量化麦克默多干旱山谷中泰勒谷的山坡水、溶质和碳预算，使用水迹调查近地表地质过程，并挑战浅层地下水最少或不存在的范式。水迹是高土壤水分的线性区域，在多年冻土区占主导地位的土壤中，这些区域将浅层地下水引导至下坡。本文将检验四个假设：（1）水迹是水和溶质运移的重要途径;（2）泰勒谷水迹比溪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）排出高地地形的水迹主要是湿度分离的盐水，而排出低地地形的水迹主要是海洋气溶胶;（4）水迹是泰勒谷陆地土壤碳含量最高、CO2通量最强的部位，其碳含量随土壤年龄的增加而增加，而碳通量随年龄的增加而减少。为了检验这些假设，PI将进行一系列由建模和遥感支持的实地测量。他们将在泰勒谷的地质、气候和地形条件范围内的水道上安装浅永冻土威尔斯井。多频电磁感应探测的上部~1米的永久冻土将创建第一个全面的土壤湿度图在泰勒谷，并将允许直接量化的水跟踪流量在整个山谷。更广泛的影响：俄勒冈州州立大学的非科学专业学生将通过一个新的全球环境变化课程，重点是南极洲的科学方法，被纳入拟议的研究。三名本科生，代表性不足的少数民族成员，将被卷入研究，将有助于现场和实验室科学的各个方面，并将在全国会议上提出结果。

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.