Absence of carbon isotope fractionation of individual n-alkanes in a 23-year field decomposition experiment with Calluna vulgaris

Distributions and carbon isotope compositions of individual n-alkanes have been monitored during a 23-year decomposition experiment using litter-bags of Calluna vulgaris shoots buried in a peat bog in the Moor House Nature Reserve. After 23 years, up to 90% of weight loss had occurred for both bulk litter and for the C23---C35 n-alkane fractions. However, such extensive degradation was not accompanied by molecular carbon isotope fractionation — the δ13C values of individual n-alkanes remained virtually unchanged. Biomarker n-alkane δ13C values are thereby further validated as proxies for palaeoenvironmental reconstruction and as tracers of carbon flow in soils and sediments