HR: 1340h
AN: B13A-0213    [Abstracts]
TI: Abiotic Organic Chemistry in Hydrothermal Systems.
AU: Simoneit, B R
EM: simoneit@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin. Bldg, Corvallis, OR 97331-5503 United States
AU: * Rushdi, A I
EM: rushdia@onid.orst.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, 104 COAS Admin. Bldg, Corvallis, OR 97331-5503 United States
AB: Abiotic organic chemistry in hydrothermal systems is of interest to biologists, geochemists and oceanographers. This chemistry consists of thermal alteration of organic matter and minor prebiotic synthesis of organic compounds. Thermal alteration has been extensively documented to yield petroleum and heavy bitumen products from contemporary organic detritus. Carbon dioxide, carbon monoxide, ammonia and sulfur species have been used as precursors in prebiotic synthesis experiments to organic compounds. These inorganic species are common components of hot spring gases and marine hydrothermal systems. It is of interest to further test their reactivities in reductive aqueous thermolysis. We have synthesized organic compounds (lipids) in aqueous solutions of oxalic acid, and with carbon disulfide or ammonium bicarbonate at temperatures from $175-400\deg$C. The synthetic lipids from oxalic acid solutions consisted of n-alkanols, n-alkanoic acids, n-alkyl formates, n-alkanones, n-alkenes and n-alkanes, typically to C$_{30}$ with no carbon number preferences. The products from CS$_{2}$ in acidic aqueous solutions yielded cyclic thioalkanes, alkyl polysulfides, and thioesters with other numerous minor compounds. The synthesis products from oxalic acid and ammonium bicarbonate solutions were homologous series of n-alkyl amides, n-alkyl amines, n-alkanes and n-alkanoic acids, also to C$_{3}$0 with no carbon number predominance. Condensation (dehydration) reactions also occur under elevated temperatures in aqueous medium as tested by model reactions to form amide, ester and nitrile bonds. It is concluded that the abiotic formation of aliphatic lipids, condensation products (amides, esters, nitriles, and CS$_{2}$ derivatives (alkyl polysulfides, cyclic polysulfides) is possible under hydrothermal conditions and warrants further studies.
DE: 7218 Lithosphere and upper mantle
DE: 4815 Ecosystems, structure and dynamics
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3035 Midocean ridge processes
DE: 1020 Composition of the crust
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting