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Biogeochemical properties of soils play a crucial role in soil and stream chemistry throughout a watershed. How water interacts with soils during subsurface flow can have impacts on water quality, thus, it is crucial to understand where and how certain soil water chemical processes occur within a catchment. In this study, ~200 soil samples were evaluated throughout a small catchment in Manitou Experimental Forest to examine spatial and vertical patterns in major soil solutes among different landscape units: riparian areas, alluvial fans, and steep hillslopes. Solutes were extracted from the soil samples in the laboratory and analyzed for major cations (Li, K, Mg, Br, and Ca) and anion (Fl, Cl, NO2, NO3, PO4, and SO4) concentrations using ion chromatography. Concentrations of most solutes were greater in near surface soils (10cm) than in deeper soils (100cm) across all landscape units, except for fluoride which was found to increase with depth. Potassium was found to have the highest variation between depths, with the largest range of 1.039mg/l (100cm) to 3.127mg/l (10cm) being in riparian areas. Nearly every solute was found to be enriched in riparian areas, with mean concentrations being higher than the hillslopes and fans, NO3 being the only notable exception with concentrations greater in the alluvial fans. Br, NO2, and PO4 concentrations were often below the detectable limit, and Li and Na were not variable between depths or landscape units. Overall, based on the comparisons between depths and landscape units, findings suggest that K, Mg, Ca, Fl, and NO3 solutes may serve as valuable tracers to identify subsurface flowpaths from different landscape units and depth within this catchment.

Reece.Gregory@babyÖ±²¥app.EDU

Geography Undergraduate Student, CU Boulder