HR: 0830h
AN: B51C-0979    [PDF]
TI: Lipid Composition of Soil Profiles and Water-Soluble Colloids Collected Within the Atlantic Coastal Plain in South Carolina
AU: * Mills, G L
EM: mills@srel.edu
AF: Savannah River Ecology Laboratory, U. of Georgia, Postal Drawer E, Aiken, SC 29802 United States
AU: Herbert, B E
EM: herbert@geo.tamu.edu
AF: Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843 United States
AU: Bertsch, P M
EM: bertsch@srel.edu
AF: Savannah River Ecology Laboratory, U. of Georgia, Postal Drawer E, Aiken, SC 29802 United States
AB: The Atlantic Coastal Plain physiographic unit of the eastern US represents a large land area ranging from Mississippi to New Jersey. Soils widely distributed in this physiographic unit are characterized by highly weathered, deep coarse textured vadose zones, located on mature landscapes. Furthermore, soil types common in the upper coastal plain (UCP) region have strong similarities to soils widely distributed in watersheds of the Amazon Basin. Thus, an understanding of the biogeochemical dynamics controlling carbon fluxes in these systems has significant implications for natural resource management of large land areas and for the potential to enhance C-sequestration in the terrestrial biosphere. We have examined the distributions of lipids in vertical profiles in upland soils within the UCP. Our results showed that biogenic hydrocarbons, fatty acids, and aliphatic alcohols decreased with increasing depth within the soil profiles. However, differences were observed within subgroups of the lipid classes. The concentration of unsaturated fatty acids decreased markedly in the subsoil horizons while cuticular fatty acids increased. This was especially pronounced when considered as a relative proportion of total lipids. The alcohol fraction was dominated by long-chain aliphatic alcohols of cuticular origin which also increased in relative proportion with depth. Additional studies of a selected profile showed that the lipid composition of the colloidal fraction extracted with water from the surface horizon closely resembled the lipid composition of the deeper soil horizon. These results are corroborated by mineralogical analysis of colloids associated with subsoils which suggest they are derived from the surface the horizons and suggest that the colloidal phase plays an important role in controlling the flux of these cuticular lipid components to the deep sandy, E horizon subsoils.
DE: 1045 Low-temperature geochemistry
DE: 1055 Organic geochemistry
SC: Biogeosciences [B]
MN: 2003 Fall Meeting