The Preservation and Interpretation of δ³⁴S Values in Charred Archaeobotanical Remains

Abstract

The measurement of sulphur isotope (δ 34 S) values in charred plant remains has the potential to inform understanding of the spatial configuration and ecology of crop production. We investigated the effects of charring, manuring, oxidation and anaerobic soil conditions on modern cereal grain/pulse seed δ 34 S values, and assessed the effect of chemical pre-treatment on charred modern and archaeobotanical grain/seed δ 34 S values. We used these results to interpret δ 34 S values in archaeobotanical material from Neolithic Çatalhöyük. Our results suggest that δ 34 S values can be reliably preserved in charred grain/seeds but are subject to influence by anaerobic soil conditions, the effect depending on the timing of flooding in relation to S assimilation.

Radiocarbon chronology and environmental context of Last Glacial Maximum human occupation in Switzerland

“…As such, δ 34 S values are spatially variable and often considered a tool for exploring mobility and landscape utilisation 38,52,53 . However, bone collagen δ 34 S values may also hold significant promise as a palaeoenvironmental proxy representing changing hydrological and microbial processes 51,54,55 . In this study, bone collagen stable isotope analyses are performed on the 4 dated specimens, plus a further 7 reindeer bones from Kastelhöhle-Nord intermediate horizon.…”

“…Reindeer δ 34 S values reflect the soil δ 34 S values upon which they fed. Soil δ 34 S values are related to underlying lithology and can be altered through changing rates of mineral weather and soil-bedrock interactions, controlled by hydrological conditions and bacterially-mediated reduction and oxidation processes 51,54,55 . The surface lithology of the regions compared (southwest France, northern Swiss Jura, and French Jura) are underlain by similar late Mesozoic and Cenozoic limestone and sandstone deposits 72 , which are unlikely to vary in δ 34 S values to the extent observed in the reindeer data.…”

“…This suggests environmental parameters are influential in the observed signal. Low environmental δ 34 S values have been related to low oxygen/water-logged soil conditions, though the processes that govern these fractionations are complex and not yet fully understood 55,[73][74][75] . It is therefore possible that the lower δ 34 S values observed in the Swiss samples, compared to the French samples, could indicate an environment that had experienced wetter/more oxygen limited soil conditions.…”

Magdalenian and Epimagdalenian chronology and palaeoenvironments at Kůlna Cave, Moravia, Czech Republic

“…4 ) supports this interpretation. Low soil δ 34 S values are produced in anaerobic environments, such as those that are water-logged (Fry et al 1982 ; Bottrell and Novak 1997 ), and while the exact mechanisms by which this low δ 34 S sulphur becomes available to plants are not yet fully understood, low plant δ 34 S values are known to occur in these anaerobic environments, or in environments where aerobic soil conditions have recently been re-established after water-logging (Bottrell and Novák 1997 ; Björkvald et al 2009 ; Nitsch et al 2019 ). Therefore, we suggest the observed change in δ 34 S values in the Kůlna Cave data most likely indirectly record changing soil hydrological conditions between c. 15,600 and 14,900 cal.…”

“…Both faunal δ 15 N and δ 34 S values reflect underlying soil processes related to different aspects of the soil environment (e.g. temperature, nutrient status, microbial activity, water and oxygen content, underlying lithology (Thode 1991 ; Amundson et al 2003 ; Craine et al 2015a , b ; Nehlich 2015 ; Nitsch et al 2019 )). Therefore, combined δ 13 C, δ 15 N, and δ 34 S analysis of archaeological fauna can be used to better understand the terrestrial environment in which people hunted.…”