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Exploring the Effect of Aspect to Inform Future Earthcasts of Climate‐Driven Changes in Weathering of Shale
Author(s) -
Sullivan P. L.,
Goddéris Y.,
Shi Y.,
Gu X.,
Schott J.,
Hasenmueller E. A.,
Kaye J.,
Duffy C.,
Jin L.,
Brantley S. L.
Publication year - 2019
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1029/2017jf004556
Subject(s) - weathering , soil water , soil production function , precipitation , parent material , environmental science , climate change , watershed , soil science , geology , kaolinite , earth science , drainage basin , dissolution , hydrology (agriculture) , pedogenesis , mineralogy , geomorphology , chemistry , geography , meteorology , oceanography , cartography , geotechnical engineering , machine learning , computer science
Projections of future conditions within the critical zone—earthcasts—can be used to understand the potential effects of changes in climate on processes affecting landscapes. We are developing an approach to earthcast how weathering will change in the future using scenarios of climate change. As a first step here, we use the earthcasting approach to model aspect‐related effects on soil water chemistry and weathering on hillsides in a well‐studied east‐west trending watershed (Shale Hills, Pennsylvania, USA). We completed model simulations of solute chemistry in soil water with and without the effect of aspect for comparison to catchment observations. With aspect included, aqueous weathering fluxes were higher on the sunny side of the catchment. But the effect of aspect on temperature (0.8 °C warmer soil on sunny side) and recharge (100 mm/year larger on shaded side) alone did not explain the magnitude of the observed higher weathering fluxes on the sunny side. Modeled aspect‐related differences in weathering fluxes only approach field observations when we incorporated the measured differences in clay content observed in augered soils on the two hillslopes. We also had to include a biolifting module to accurately describe cation concentrations in soil water versus depth. Biolifting lowered some mineral dissolution rates while accelerating kaolinite precipitation. These short‐duration simulations also highlighted that the inherited differences in particle size on the two sides of the catchment might in themselves be explained by weathering under different microclimates caused by aspect—over longer durations than simulated with our models.