Historical mining sites: biomineral processes, environmental resilience and implications for risk analysis and management

Mine polluted areas account for ca. 0.1 per cent of the total land surface. Mine wastes are transported by rivers to the oceans resulting also there in chemical pollution. Mine pollution, thus, must be considered a global environmental problem. However, we still have poor knowledge on the global impact of chemical pollution and the response of our ecosystems to mine pollution perturbation. Minerals, microbes, plants, water and air are all compartments of the ecosystems. Environmental resilience can be promoted by one of these compartments and it is generally sustained by the interaction among many of them. Moreover, state of the art knowledge on the effect of mineral reactions at larger scale allows one to recognize environmental drivers. Such a knowledge also can make a difference in resource and environmental management. This seminar will illustrate a case study in SW Sardinia (Italy) revealing a dynamic response of the environment to pollution, and its implications for risk analysis. In the study area (Iglesiente and Arburese mine districts), mine activities linked to Zn and Pb extraction from sulphides and calamine ores, left a seriously impacted environment due to widespread dumps of highly contaminated (Zn, Pb, Fe, Cd, etc.) mining residues. Authigenic metal sulphides occur due to sulphate reducing bacteria (SRB) under favourable conditions in the riverbed. When erosional processes do not prevail and thick muddy sediments lay in the hyporheic zone, biomineral processes occur also in plant systems (Phragmites australis, Juncus acutus) and are part of the resilient response of the environment to mine pollution. This seminar will highlight implications for management and circular economy.