Antarctic water track hydrology and geochemistry from drone and ground sensors: active layer wetland processes in a cold desert

Abstract

We report on drone-borne remote sensing and ground-based geochemical results from water track soils collected in 2022-2023 in the McMurdo Dry Valleys of Antarctica that aim to address how much water is flowing through Antarctic water tracks, what remote sensing reveals about water track melt sources, and what impacts water track flow has on soil biogeochemical processes that may be leading to soil development in the water tracks. Water tracks were measured using drone-borne remote sensing: a Headwall Extended VNIR imaging spectrometer (900-1700 nm spectral range). Soil moisture content was measured during UAV flights using co-located soil moisture probes and was extrapolated beyond probe locations across the water track and adjacent dry soil using a linear fit between in situ measured water content and the depth of the 1.4 µm reflectance spectrum absorption feature associated with water. We report on ground-truth measurements of sediment characteristics, organic matter content, and dissolved silica and clay properties (abundance, soil texture, and exchange chemistry) to evaluate whether Antarctic water tracks are in a positive feedback loop, in which wetting of previously dry ground results in enhancement of soil organic matter, enhanced chemical weathering, and leading to longer wetted periods. This work expands on previous studies by presenting multiple wavelengths of remote sensing data, further refining the water budget for the Antarctic active layer, and by integrating deeper soil sensor and ground-truth measurements to explore the range of biogeochemical processes at work in these Antarctic wetland features.