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Applications of Aliphatic Biomarker Distributions and Compound-Specific 13C and D Analyses in Assessing Long Term Environmental Change in the Florida Everglades

Ding He, Blanca Jara, Laura Belicka, and Rudolf Jaffé
1Department of Chemistry & Biochemistry, Southeast Environmental Research Center, Florida International University, Miami, FL, USA.

Hydrocarbons are abundant lipid molecules biosynthesized by various organisms and often found to be resistance to degradation during sedimentation. Their distribution patterns and other related parameters such as Paq (% of aquatic plants), CPI (carbon preference index), ACL (average chain length) can be utilized for tracing organic matter sources and to reveal diagenetic transformations. In addition, hydrocarbons in sediments are well known to record δ13C and δD values from their original sources, which may provide detailed information historical source variations of the sedimentary OM. In this study the combined approache of biomarkers and compound specific isotope analysis was used to determine specific source contributions to particulate and soil OM, and to reconstruct long term environmental change in the Florida Everglades system. A series of mono-methylalkanes (MMAs) (C10 to C21) mainly derived from bacteria, algae and other micro-organisms were tentatively identified in Everglades periphyton, floc and soils, and potential sources and early diagenetic transformations revealed. In addition, n-alkane distributions and compound- specific stable isotope composition studies demonstrate that historical (past century) hydroperiod (depth and time on inundation) changes are reflected in vegetation shifts from slough type plants to ridge type plants in the Everglades . All in all, molecular charcterizations in combination with compound specific stable isotope analyses were successfully applied in this system to reconstruct anthropogenically-induced hydrological change.

AAPG Search and Discovery Article #90182©2013 AAPG/SEG Student Expo, Houston, Texas, September 16-17, 2013