Tracing higher plant inputs into coastal sediments: and integrated isotopic and molecular approach for forensic investigation

TY - CHAP

T1 - Tracing higher plant inputs into coastal sediments: and integrated isotopic and molecular approach for forensic investigation

AU - Eley, Yvette

AU - Pedentchouk, Nikolai

AU - Dawson, Lorna

PY - 2012

Y1 - 2012

N2 - The relationship between surface vegetation and organic material contained within soils and sediments can represent an important source of information when attempting to link a questioned soil sample taken as part of a forensic investigation to a location of interest. n-Alkanes contained within plant leaf waxes represent a valuable resource of information as they are well-preserved in soils and sediments. Molecular distribution patterns of n-alkanes regularly overlap in the n-C23 to n-C35 range at species level, however, which can limit their usefulness in forensic inquiries. Compound-specific stable isotopic analysis of plant and soil long-chain n-alkanes from leaf lipids has been shown to provide greater resolution when seeking to discriminate between plant species than analysis of molecular distribution parameters alone. Here, we present n-alkane molecular, δ13C and δD data from plant and sediment samples collected from Stiffkey on the north Norfolk coast of the UK during February 2011 from locations ranging from sand flat to high marsh. This site contains diverse vegetation including C3 and C4 grasses (Spartina anglica and Elytrigia atherica), along with succulent species (Suaeda vera), and dicots (such as Limonium vulgare and Atriplex portulacoides). We observed differences of >16‰ among all species with respect to n-C29 δ13C (with >10‰ between C3 species alone), and > 70‰ when considering n-C29 δD, illustrating that isotope variation at the compound-specific level is significant between species and plant types. Multivariate statistical analysis of surface sediment samples taken from the marsh demonstrates that they reflect the isotopic and molecular distributions of the particular vegetation assemblages overlaying them. Our study shows that a combined molecular and isotopic analytical approach to higher plant n-alkane analysis in a forensic context could enhance resolution when recreating surface vegetation assemblages and thus be a useful approach when provenancing soils.

AB - The relationship between surface vegetation and organic material contained within soils and sediments can represent an important source of information when attempting to link a questioned soil sample taken as part of a forensic investigation to a location of interest. n-Alkanes contained within plant leaf waxes represent a valuable resource of information as they are well-preserved in soils and sediments. Molecular distribution patterns of n-alkanes regularly overlap in the n-C23 to n-C35 range at species level, however, which can limit their usefulness in forensic inquiries. Compound-specific stable isotopic analysis of plant and soil long-chain n-alkanes from leaf lipids has been shown to provide greater resolution when seeking to discriminate between plant species than analysis of molecular distribution parameters alone. Here, we present n-alkane molecular, δ13C and δD data from plant and sediment samples collected from Stiffkey on the north Norfolk coast of the UK during February 2011 from locations ranging from sand flat to high marsh. This site contains diverse vegetation including C3 and C4 grasses (Spartina anglica and Elytrigia atherica), along with succulent species (Suaeda vera), and dicots (such as Limonium vulgare and Atriplex portulacoides). We observed differences of >16‰ among all species with respect to n-C29 δ13C (with >10‰ between C3 species alone), and > 70‰ when considering n-C29 δD, illustrating that isotope variation at the compound-specific level is significant between species and plant types. Multivariate statistical analysis of surface sediment samples taken from the marsh demonstrates that they reflect the isotopic and molecular distributions of the particular vegetation assemblages overlaying them. Our study shows that a combined molecular and isotopic analytical approach to higher plant n-alkane analysis in a forensic context could enhance resolution when recreating surface vegetation assemblages and thus be a useful approach when provenancing soils.

KW - leaf wax biomarkers

KW - environmental forensics

M3 - Chapter (peer-reviewed)

SP - 218

EP - 231

BT - Environmental Forensics: Proceedings of the 2011 INEF Conference

A2 - Morrison, Robert

A2 - O'Sullivan, Gwen

PB - The Royal Society of Chemistry

ER -