R&D Activities Communication

SMM 2021: New approaches in the study of medieval settlement.

Mercury in burials: a new methodological approach for understanding its behaviour in soils/sediments from Late Antiquity inhumations.

Noemi Álvarez Fernández, Antonio Martínez Cortizas, Olalla López Costas

Abstract

Mercury is a major environmental pollutant that given its toxicity is considered of global public health concern. The study of mercury concentrations on human archaeological remains shows that this element had an impact even on past-populations with low mining-metallurgical activity, as it happened during the Late Antiquity in SW Europe. Mercury target organs are soft tissues (mainly kidney, liver and nervous system) not bones, which drives to the question of how this element behaves in the inhumations? and is it possible to detect its signal in soil associated to low polluted individuals? and which are the factors that affects its distribution or accumulation?

In this study we analysed elemental composition (23 elements) and mercury concentrations in 46 soil/sediment samples from two Late Antiquity tombs of A Lanzada site (Galicia, NW Spain) (AD 5th-6th centuries) and then model its behaviour using PLS-regression. Three processes modelling mercury distribution have been identify: i) inside/outside burial, i.e. mercury comes from the individuals not from soil; ii) inter-individuals differences, since one burial contained the remains of an elder woman and the other one is a coetaneous burial with two men (one juvenile and one mature adult); and iii) micro-scale processes variability that in some cases could be related with thoracic area proximity. As a conclusion we can said that: i) human bodies act as source of mercury and as they provided organic matter also contributes to mercury fixation; ii) the burial context seems to affect its distribution; iii) thoracic area could have a role in mercury distribution. Finally, this study remarks the importance of analysing soil/sediments associated to the burials. They could also be used as an indirect approximation of mercury skeletons content. In addition, Early Medieval is confirmed as low mercury pollution period with less impact in human remains, especially when comparing with Roman times.

REFERENCES

  • Noemi Álvarez–Fernández, Antonio Martínez Cortizas, Zaira García–López, Olalla López–Costas (2021) Approaching mercury distribution in burial environment using PLS-R modelling. Scientific reports. https://doi.org/10.1038/s41598-021-00768-8