HR: 11:20h
AN: B22C-05 INVITED    [Abstracts]
TI: Soil mineral control on organic matter composition across the long substrate age gradient (LSAG) chronosequence in Hawaii
AU: * Kramer, M
EM: mkramer@es.ucsc.edu
AF: UC Santa Cruz, Dept. of Earth and Planetary Sciences, 1156 High Street, Santa Cruz, CA 93106, United States
AU: Marin, A
EM: amarin@gmail.com
AF: UC Santa Cruz, Dept. of Earth and Planetary Sciences, 1156 High Street, Santa Cruz, CA 93106, United States
AU: Chadwick, O
EM: oac@geog.ucsb.edu
AF: UC Santa Barbara, Dept. of Geography, Santa Barbara, CA 95064, United States
AB: We examined the composition of organic matter in relation to soil mineralogy across the long substrate age gradient (LSAG) chronosequence in Hawaii. Our objectives were to 1) determine the types of SOM that accumulate across lava flows of increasing age, and 2) examine possible mechanisms for SOM stabilization, and 3) assess the relationship between shifts in soil mineralogy and organic matter composition. Sequentially deeper soil samples were collected across 6 LSAG sites of increasing age (300 y - 4.1My). Samples from major diagnostic soil horizons were analyzed for nitrogen stable isotope ratios and carbon composition using solid- state 13C nuclear magnetic resonance (NMR). Abundance of soil metals and mineral type (primary, non- crystalline, and crystalline) was determined using a sequential chemical extraction procedure. Nitrogen stable isotope ratios, C/N and 13C NMR trends in depth profiles were examined in relation to mineral composition and soil metal abundance.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting