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While the use of fire has long been recognised as a crucial innovation in the cultural evolution of humankind, much research has focused on the (debated) chronology of its earliest use and control, and less on the ways in which fire was used in the deep past. At its latest by the Upper Palaeolithic, hunter-gatherers routinely used fire to heat a wide range of materials, adjusting parameters like temperature, exposure time and fuel type to the specific requirements of the treated materials, for instance in food preparation or tool production. Comparing analyses of the chemical and physical properties of modern materials, heated under a range of controlled conditions in a laboratory, to archaeological ones might allow the reconstruction of the “heating history” of excavated materials and hence to infer the function of particular fires in the past - provided changes affecting the properties of the heated archaeological material during burial time are taken into consideration. To investigate the feasibility of such an approach, heated materials sampled from ~40,000 to 25,000 year old fireplaces (hearths) and their sedimentary matrices from the Upper Palaeolithic Abri Pataud rock shelter in South-Western France are used here to study (1) the fuel type(s) used by the site's occupants, (2) the temperatures reached in fireplaces and (3) the potential changes in human activities related to fireplaces over time, with the influence of post-depositional processes taken into explicit consideration throughout. For this purpose, we used a range of methods to analyse macroscopically visible as well as “invisible” (microscopic and molecular) heat-altered materials. The results suggest that charred organic materials (COM) encountered in the samples predominantly result from the fuel used in fireplaces, including the earliest reported use of dung as fuel. Earlier suggestions about the use of bone as fuel at the Abri Pataud are not supported by this study. The heating temperature of

An inventory of lipid biomarkers in suspended particulate matter (SPM) from Lake Chala, a meromictic crater lake, was made, and then coupled to physical changes within the lake water column. Diatom blooms, which occur during periods of deep mixing were found to be reflected by compounds such as (iso)loliolide, methyl-9,10-dihydroxyoctanoate and 23-methylcholesta-5,22-dienol. A aglycone triol, 1,3,25-hexacosanetriol, was found to covary with a C19:1 alkene that was previously linked to the occurrence of cyanobacteria. The majority of sterols, even though they form the most abundant group of lipid biomarkers within Lake Chala, are not exclusively indicative of a singular variable within the lake. Their signal appears to be a combined signal of influx of plant material from within the crater and in-situ production by organisms in the water column. The same applies for three n-alkanols (tetra-, hexa- and octadecanol), however based on their short chain length, a phytoplankton source is still the most probable major source. Lastly, two diols, 2,23-C24 diol and 2,25-C26 diol were found predominantly in the anoxic region of the lake, extending to the surface during deep mixing. Although their producing organisms are unknown, previous studies have linked their occurrence to anoxic conditions.

An inventory of lipid biomarkers in suspended particulate matter (SPM) from Lake Chala, a meromictic crater lake, was made, and then coupled to physical changes within the lake water column. Diatom blooms, which occur during periods of deep mixing were found to be reflected by compounds such as (iso)loliolide, methyl-9,10-dihydroxyoctanoate and 23-methylcholesta-5,22-dienol. A aglycone triol, 1,3,25-hexacosanetriol, was found to covary with a C19:1 alkene that was previously linked to the occurrence of cyanobacteria. The majority of sterols, even though they form the most abundant group of lipid biomarkers within Lake Chala, are not exclusively indicative of a singular variable within the lake. Their signal appears to be a combined signal of influx of plant material from within the crater and in-situ production by organisms in the water column. The same applies for three n-alkanols (tetra-, hexa- and octadecanol), however based on their short chain length, a phytoplankton source is still the most probable major source. Lastly, two diols, 2,23-C24 diol and 2,25-C26 diol were found predominantly in the anoxic region of the lake, extending to the surface during deep mixing. Although their producing organisms are unknown, previous studies have linked their occurrence to anoxic conditions.

This article presents a set of Late Pleistocene marine mollusk radiocarbon (AMS) age estimates of 30-50 14C kyr BP, whereas a MIS5 age (>75 ka) is indicated by quartz and feldspar OSL dating, biostratigraphy, U-Th dating, and age-depth relationships with sea level. These results indicate that the 14C dates represent minimum ages. The age discrepancy suggests that the shells are contaminated by younger carbon following shell death. The enigmatic 14C dates cannot be "solved" by removing part of the shell by stepwise dissolution. SEM analysis of the Late Pleistocene shells within a context of geologically younger (recent/modern, Holocene) and older (Pliocene) shells shows the presence of considerable amounts of an intracrystalline secondary carbonate precipitate. The presence of this precipitate is not visible using XRD since it is of the same (aragonitic) polymorph as the original shell carbonate. The combination of nanospherulitic-shaped carbonate crystals, typical cavities, and the presence of fatty acids leads to the conclusion that the secondary carbonate, and hence the addition of younger carbon, has a bacterial origin. As shell material was studied, this study recommends an assessment of possible bacterial imprints in other materials like bone collagen as well.

The TEX86 is a proxy based on a ratio of pelagic archaeal glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), and used for estimating past sea water temperatures. Concerns exist that in situ production of GDGTs lipids by sedimentary Archaea may affect its validity. In this study, we investigated the influence of benthic GDGT production on the TEX86 by analyzing the concentrations and distributions of GDGTs present as intact polar lipids (IPLs) and as core lipids (CLs) in three sediment cores deposited under contrasting redox conditions across a depth range from 900 to 3000 m below sea level in and below the Arabian Sea oxygen minimum zone (OMZ). Direct analysis of IPLs with crenarchaeol as CL via HPLC/ESI-MS2 revealed that surface sediments in the OMZ were relatively depleted in the phospholipid hexose, phosphohexose (HPH)-crenarchaeol compared to suspended particulate matter from the water column, suggesting preferential and rapid degradation of this IPL. In sediment cores recovered from deeper, more oxic environments, concentrations of HPH-crenarchaeol peaked at the surface, probably due to in situ production by ammonia-oxidizing Archaea, followed by a rapid decrease with increasing depth. No surface maximum was observed in the sediment core from within the OMZ. In contrast, the glycolipids, monohexose-crenarchaeol and dihexose-crenarchaeol, did not change in concentration with depth in the sediment, indicating that they were relatively well preserved and likely mostly derived from fossil pelagic GDGTs.These results suggest that phospholipids are more sensitive to degradation, while glycolipids might be preserved over longer time scales, in line with previous incubation and modeling studies. Furthermore, in situ produced IPL-GDGTs did not accumulate as IPLs, and did not influence the CL-TEX86. This suggests that in-situ produced GDGT lipids were more susceptible to degradation than fossil CL and IPL and did not accumulate as CL. In agreement, no significant

Until now little is known about the role vegetation plays in the organic matter formation, particularly at the molecular level. Most ecosystems have a long history, which is unknown or too complex to find distinct relations between vegetation and the chemical composition of soil organic matter. To gain a better insight in such relationships, the relative simple soil-vegetation system of the Hulshorster Sands and Leuvenum Forest is used. The complete vegetation succession has been investigated, making it possible to monitor the organic matter development. During the succession, thus with time, the pH decreases, the ectorganic layer becomes thicker and the soil develops towards a micro-podzol.Chapter 2 describes the organic matter composition and relation to the first stages of vegetation development in the pre-podzol phase. In the Ah horizon under grass ( Corynephorus canescens ), the organic matter has virtually no contribution of the covering vegetation. Algae, from an earlier stage, and mosses ( Polytrichum piliferum and Bryum sp.), from adjacent spots, are the main suppliers. Under mosses, the organic matter is very similar to that of the original species. An aliphatic biopolymer, derived from mosses, that produces a series of branched alkene/alkane doublets (C 20 -C 32 ) together with a homologous series of n -alkenes and n -alkanes (C 10 up to C 34 ) upon pyrolysis, appears to be very recalcitrant in the first stages of succession.In the vegetation stages following mosses, these aliphatic macromolecules are still an important source of the aliphatic part of organic matter. Apart from the aliphatic moss contribution, the organic matter under Callunavulgaris and Pinus sylvestris has a close relationship with the contributing plant parts: flowers, leaves and branches dominate the organic layer under Calluna , needles predominate the ectorganic horizon under pines, and the soil organic matter in the Ah horizons in both cases is almost completely determined by roots