Hydrologic Assessment of Biogeochemical Interactions at the Sub-Meter Scale

Antonio Alves Meira Neto1, Aditi Sengupta2, Yadi Wang3, Jon Chorover3, Ty Ferré1, Peter Troch1

1Department of Hydrology and Atmospheric Sciences

2Biosphere 2

3Department of Soil, Water, and Environmental Science

The University of Arizona

The understanding of processes in the critical zone (CZ) is dependent on studies linking the fields of hydrology, microbiology, geochemistry and soil development. Additionally, there is needed to integrate hydrologic information into biogeochemical analysis of subsurface environments. This study investigated potential hydrological indexes that help explaining spatial biogeochemical patterns observed at the sub-meter scale. The miniLEO is a 2 m3, 10 degree sloping lysimeter located at Biosphere 2 - University of Arizona. The lysimeter was initially filled with pristine basaltic soil and subject to intermittent rainfall applications throughout the period of 18 months followed by its excavation, resulting in a grid-based sample collection at 324 locations. As a result, spatially distributed microbiological and geochemical patterns as well as soil physical properties were obtained. A hydrologic model was developed to simulate the history of the system until its excavation. Following the model calibration, the resulting distributed fields of flow velocities and moisture states were retrieved and translated into hydrologic indices. This study explores what are the relevant hydrologic mechanisms controlling the biogeochemical signatures at the sample scale.