Store Mosse (the 'Great Bog' in Swedish) is one of the most extensive bog complexes in southern Sweden (~77 km 2 ), where pioneering palaeoenvironmental research has been carried out since the early 20th century. This includes, for example, vegetation changes, carbon and nitrogen dynamics, peat decomposition, atmospheric metal pollution, mineral dust deposition, dendrochronology, and tephrochronology. Even though organic matter (OM) represents the bulk of the peat mass and its compositional change has the potential to provide crucial ecological information on bog responses to environmental factors, peat OM molecular composition has not been addressed in detail. Here, a 568-cmdeep peat sequence was studied at high resolution, by attenuated reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) in the mid-infrared region (4000-400 cm -1 ). Principal components analysis was performed on selected absorbances and change-point modelling was applied to the records to determine the timing of changes. Four components accounted for peat composition: (i) depletion/accumulation of labile (i.e. carbohydrates) and recalcitrant (i.e. lignin and other aromatics, aliphatics, organic acids and some N compounds) compounds, due to peat decomposition; (ii) variations in N compounds and carbohydrates; (iii) residual variation of lignin and organic acids; and (iv) residual variation of aliphatic structures. Peat decomposition showed two main patterns: a long-term trend highly correlated to peat age (r = 0.87), and a short-term trend, which showed five main phases of increased decomposition (at ~8.4-8.1, ~7.0-5.6, ~3.5-3.1, ~2.7-2.1 and ~1.6-1.3 ka)mostly corresponding to drier climate and its effect on bog hydrology. The high peat accumulation event (~5.6-3.9 ka), described in earlier studies, is characterized by the lowest degree of peat decomposition of the whole record. Given that FTIR-ATR is a quick, nondestructive, cost-effective technique, our results indicate that it can be applied in a systematic way (including multicore studies) to peat research and provide relevant information on the evolution of peatlands.

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Mercury environmental cycle and toxicology have been widely researched. Given the long history of mercury pollution, researching mercury trends in the past can help to understand its behaviour in the present. Archaeological skeletons have been found to be useful sources of information regarding mercury loads in the past. In our study we applied a soil multi-sampling approach in two burials dated to the 5th to 6th centuries AD. PLRS modelling was used to elucidate the factors controlling mercury distribution. The model explains 72% of mercury variance and suggests that mercury accumulation in the burial soils is the result of complex interactions. The decomposition of the bodies not only was the primary source of mercury to the soil but also responsible for the pedogenetic transformation of the sediments and the formation of soil components with the ability to retain mercury. The amount of soft tissues and bone mass also resulted in differences between burials, indicating that the skeletons were a primary/secondary source of mercury to the soil (i.e. temporary sink). Within burial variability seems to depend on the proximity of the soil to the thoracic area, where the main mercury target organs were located. We also conclude that, in coarse textured soils, as the ones studied in this investigation, the finer fraction (i.e. silt + clay) should be analysed, as it is the most reactive and the one with the higher potential to provide information on metal cycling and incipient soil processes. Finally, our study stresses the need to characterise the burial soil environment in order to fully understand the role of the interactions between soil and skeleton in mercury cycling in burial contexts.

In Archaeology much emphasis is dedicated to bone preservation, but less attention is paid to the burial soil (i.e., Necrosol), despite its crucial role in governing the geochemical environment. The interaction between human remains and sediments starts after inhumation, leading to bidirectional physico-chemical changes. To approach these complex, bidirectional processes, we sampled at high resolution (n = 46) two post-Roman wooden coffin burials (one single and another double), and the coeval paleosol (n = 20; nearby pedo-sedimentary sequence). The samples were analysed for physical (grain size, colour) and chemical (pH; LOI; elemental composition: FTIR-ATR, XRF, C, N) properties. Principal component analysis enabled to identify five main pedogenetical processes: decalcification, melanization, acidification, neoformation of secondary minerals (i.e., clays) and enrichment in phosphorus. Melanization, acidification and phosphorous enrichment seem to be convergent processes in Necrosols—irrespective of the parent material. Decalcification may be restricted to carbonate containing soil/sediments. Despite not mentioned in previous research, clay formation might also be an overall process. Compared to the local, coeval paleosol, pedogenesis in the studied burial soils was low (double burial) to moderate (single burial). Our results also emphasize the need to study the finer soil fractions, as they provide clues both on soil formation and bone diagenesis.