HR: 09:15h
AN: H51K-06    [Abstracts]
TI: Using Pore Water Chemistry to Understand Critical Zone Mineral Weathering Reactions: A Comparison of Three Tropical Watersheds
AU: * Buss, H L
EM: hlbuss@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd. MS 420, Menlo Park, CA 94025, United States
AU: White, A F
EM: afwhite@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd. MS 420, Menlo Park, CA 94025, United States
AU: Dessert, C
EM: dessert@ipgp.jussieu.fr
AF: Observatoire Volcanologique et Sismologique de Guadeloupe, Le Houelmont, Gourbeyre, 97 113, Guadeloupe
AU: Gaillardet, J
EM: gaillard@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris Cedex 05, 75252, France
AB: Geochemical, physical, biological, and hydrologic processes are tightly coupled within the critical zone and impact global and local water cycles, solute movement, weathering rates, and nutrient bioavailability. The weathering of primary minerals in regolith and at bedrock-regolith interfaces directly impacts the availability of many important soil nutrients including Mg, Ca, K, PO4, and Fe. However, surprisingly little biogeochemical data exists as a function of depth in terrestrial regolith below the rooting zone. This shortage of data hinders quantification of the coupled processes that control nutrient fluxes. Installation of nested suction soil water samplers enables multiple researchers to measure biogeochemical parameters as a function of depth. Nested suction water samplers have been installed in soil and regolith at 0.15 m to as deep as 16.0 m in two watersheds in the Luquillo Mountains of Puerto Rico and in a watershed on Basse-Terre, Guadeloupe, in the French Antilles. All three watersheds are steep, rugged, humid, and tropical, have similar vegetation and land- use, and contain thick saprolites developed on volcanic materials: a quartz diorite intrusion in the Rio Icacos watershed, Puerto Rico; marine bedded volcaniclastics in the Bisley watershed, Puerto Rico; and a volcanic debris flow in the Bras-David watershed, Guadeloupe. The two Puerto Rican watersheds are part of the USGS Water Energy and Biogeochemical Budgets (WEBB) program and also constitute a Critical Zone Exploration Network (CZEN) seed site. The Bisley watershed is also part of the Luquillo Long Term Ecological Research (LTER) site. The Guadeloupean watershed is a Critical Zone International Scholar seed site and the surface water chemistry is monitored by the Observatoire Volcanologique et Sismologique de Guadeloupe and the Institut de Physique du Globe de Paris (IPGP). In the mid 1990's the Rio Icacos watershed was instrumented with regolith gas samplers, tensiometers, and nested suction water samplers, which have been used in numerous studies by both USGS and university-affiliated scientists. Similar equipment was installed in the Bisley watershed in 2006-2007 and in the Bras-David watershed in 2007. An overview of research findings facilitated by the nested suction water samplers installed in the Rio Icacos watershed will be presented along with data from the newly instrumented Bisley and Bras-David watersheds.
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0486 Soils/pedology (1865)
DE: 1875 Vadose zone
DE: 1886 Weathering (0790, 1625)
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: 2007 Fall Meeting