Title: Geochemical Analysis of Soils, Marine Sediments, and Peat Author: Shannon Lee

Introduction This project was divided into 2 sections: 1. Elemental Analysis o Performed on Alpine soil, Galway Bay marine

sediment and Spiddal peat samples 2. Lipid Biomarker Analysis o Performed on Spiddal peat samples

Elemental Analysis – Introduction o Can provide quantitative analysis of an unknown

sample o Determines amount and variation of organic matter

(OM)

Elemental Analysis – Method o Samples are wrapped in tin capsules and placed in

a furnace with a stream of unreactive gas o Samples are burned in excess oxygen o Products (CO2, NO, H2O) are collected o % of Carbon, Hydrogen and Nitrogen can be found

using mass of sample o Marine samples are acidified with 2M HCl prior to

elemental analysis to remove carbonates

Elemental Analysis – Results

Lipid Biomarkers – Introduction o Organic biomarkers include n-alkyl compounds; n-

alkanes, n-alkanols, and n-alkanoic acids o Sources include terrestrial plants, marine algae and

micro-organisms o Highly resistant to degradation o Biomarkers from soil, marine sediments and peat can

give an indication of past climates and environmental conditions

Lipid Biomarkers – Background o Storms revealed remains of a 7500 year old

drowned forest in Spiddal, Co. Galway o Plant debris of forest floor lead to the formation of a

blanket bog

(Photos of sampling of peat from drowned forest in Spiddel, Co. Galway)

Lipid Biomarkers – Methods Free Lipid Extraction: o Sample lipids were extracted with ultrasonic solvent

extraction with organic solvents o Solvent extracts were combined and concentrated

under rotary evaporation Solid Phase Extraction (SPE): o SPE cartridges were conditioned with organic

solvents o Samples were fractionated into: Neutral Lipids, Fatty

Acids, and Polar Lipids o Lipids were collected in GC vials o

Lipid Biomarkers – Methods Derivatisation: o Neutral lipids were converted to trimethylsilyl (TMS)

derivatives with BSTFA o Fatty acids were alkylated with BF3 o Lipids were analysed with GC-MS o Polar lipids were stored as they were not needed for

the project

Lipid Biomarkers – Preliminary Results

o Abundance of C23 suggesting Sphagnum moss o Abundance of C31 suggesting Terrestrial plants

Lipid Biomarkers – Preliminary Results

o Higher ratio at 105-110 cm suggests wetter

conditions

Future Work

o Analysis of n-alkanoic acids, n-alkanols, and sterols o Extraction of the 9 remaining sample depths from

the peat profile o Carbon dating of peat profile