Monday, 7 November 2005 - 10:45 AM
76-4

Biohydrochemical Coevolution — Water and Chemical Fluxes in a Marine-Terrace Chronosequence.

David A. Stonestrom, Arthur F. White, and Marjorie S. Schulz. US Geological Survey, 345 Middlefield Rd MS-421, Menlo Park, CA 94025-3591

Contemporary and long term (geo-scale) chemical and hydraulic fluxes were evaluated by sampling and instrumenting five cosmogenically dated uplifted marine terraces 65 – 226 ka old to establish liquid- and solid-phase systematics. Soil-solution analyses and hydraulic measurements yield current chemical fluxes. Solid-state analyses and cosmogenic dating yield geo-scale chemical fluxes. Weathering, soil-forming, and biologic processes are coupled across all temporal scales. Weathering and pedogenic processes cause systematic, orders-of-magnitude shifts in hydraulic properties. These changes in hydraulic properties provide feedback by controlling water availability, redox conditions, and biologic activity. Geo-scale times series of profile evolution provide evidence of that biolifting recycles essential elements such as calcium, which would otherwise be lost from the root zone, from greater to shallower depths. Biolifting offsets long-term declines in soil productivity from weathering-induced losses of primary minerals.

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Back to The ASA-CSSA-SSSA International Annual Meetings (November 6-10, 2005)