Trace metals from historical mining sites and past metallurgical activity remain bioavailable to wildlife today

Estelle Camizuli,Claude Gourault,Stéphane Garnier,Carmela Chateau,Gilles Hamm,Caroline Lachiche,Renaud Scheifler,Fabrice Monna,Rémi Losno,Guillaume Delivet,Paul Alibert

doi:10.1038/s41598-018-20983-0

Abstract

Throughout history, ancient human societies exploited mineral resources all over the world, even in areas that are now protected and considered to be relatively pristine. Here, we show that past mining still has an impact on wildlife in some French protected areas. We measured cadmium, copper, lead, and zinc concentrations in topsoils and wood mouse kidneys from sites located in the Cévennes and the Morvan. The maximum levels of metals in these topsoils are one or two orders of magnitude greater than their commonly reported mean values in European topsoils. The transfer to biota was effective, as the lead concentration (and to a lesser extent, cadmium) in wood mouse kidneys increased with soil concentration, unlike copper and zinc, providing direct evidence that lead emitted in the environment several centuries ago is still bioavailable to free-ranging mammals. The negative correlation between kidney lead concentration and animal body condition suggests that historical mining activity may continue to play a role in the complex relationships between trace metal pollution and body indices. Ancient mining sites could therefore be used to assess the long-term fate of trace metals in soils and the subsequent risks to human health and the environment.

Highlights

The first evidence of extractive metallurgy dates from the 6th millennium BC in the Near East[1,2]
The transfer of an element from abiotic compartments to biota depends on the biological characteristics of the targeted organisms as well as the bioavailability of the element, which is influenced by the physico-chemical properties of both the pollutant and the medium[22]
The aims of the present study were (i) to quantify the level of soil contamination by four trace metals (TMs) directly linked to mining activity, (ii) to check whether these contaminants were bioavailable to organisms such as the wood mouse, and (iii) to see if contamination ever occurred at levels prejudicial to the organism’s health

Summary

Introduction

The first evidence of extractive metallurgy dates from the 6th millennium BC in the Near East[1,2]. In the Morvan and Cévennes massifs (France), the older sites remain difficult to identify in the field, in forested areas Because of their outstanding landscapes and biodiversity, both the Morvan and the Cévennes are recognized as nature parks, considered to be pristine areas, relatively free from anthropogenic impact. These areas have experienced several phases of mining and smelting, starting as early as the Bronze Age for the Morvan[13,14,15] and at least from the Iron Age for the Cévennes[16] In these parks, recent archaeological studies have identified ancient metallurgical sites, their spatial extent and the nature of their activities, together with palaeoenvironmental information[17,18]. The potential toxic effects of these elements on the local fauna were investigated by several proxies: body condition for nutritional status[24,25,26,27], somatic indices for possible histological damage[28], and fluctuating asymmetry (FA) for developmental instability[29,30]

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Conclusion