Quantification of lignin oxidation products as vegetation biomarkers in speleothems and cave drip water

Abstract

Abstract. Here we present a sensitive method to analyse lignin oxidation products (LOPs) in speleothems and cave drip water to provide a new tool for paleo vegetation reconstruction. Speleothems are valuable climate archives. However, compared to other terrestrial climate archives, such as lake sediments, speleothems contain very little organic matter. Therefore, very few studies on organic biomarkers in speleothems are available. Our new sensitive method allows to use LOPs as vegetation biomarkers in speleothems. 5Our method consists of acid digestion of the speleothem sample followed by solid phase extraction (SPE) of the organic matter. The extracted polymeric lignin is degraded in a microwave assisted alkaline CuO oxidation step to yield monomeric LOPs. The LOPs are extracted via SPE and finally analysed via ultrahigh-performance liquid chromatography (UHPLC) coupled to electrospray ionisation (ESI) and high-resolution orbitrap mass spectrometry (HRMS). The method was applied to stalagmite samples with a sample size of 3 -5 g and cave drip water samples with a sample size of 100 -200 mL from the

Towards Organic Carbon Isotope Records from Stalagmites: Coupled δ13C and 14C Analysis Using Wet Chemical Oxidation

“…Organic matter entrapped in speleothem carbonate is increasingly recognized as a promising tool for the reconstruction of past ecosystem and climate change (Bosle et al 2014;Perrette et al 2015;Quiers et al 2015;Blyth et al 2016;Heidke et al 2018). Organic carbon (OC) primarily originates either from the overlying soil and karst system from which it is transported into caves by vadose water, or from microbial production within the cave (Blyth et al 2016).…”