S8: Touro (Galicia, ES)

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Site “S-8”, Touro (A Coruña, Spain) Former Cu mine 42º52’34”N, 8º20’40”W

Brief description:

The Touro copper mine was active from 1974 until 1988, since its closure the area has been confined to extraction of material for road construction. The mine tailings cover an area of around 550 ha and are practically bare of vegetation. The geological substrate is amphibolite, with significant quantities of metal sulphides (pyrite, pyrrhotite, and chalcopyrite). The mine soils are shallow and extremely gravelly, and are classified as Spolic Technosols (Episkeletic). The uncontrolled oxidation of sulphides generates hyperacidic (pH 2-3) and hyperoxidising (>500 mvol) soils and waters, with a high electrical conductivity and high concentrations of sulphates, Fe, Al, and potentially toxic trace metal(loid)s. The climate of the region is Atlantic (oceanic), with a mean annual precipitation of 1900 mm and mean annual temperature of 12.6ºC.

The area selected for the experimental field plots was completely barren of vegetation. Three soil amendments (composted MSW or technosol mixtures elaborated by the company Tratamientos Ecológicos de Noroeste (TEN s.l.)) were incorporated in spring 2011 at an addition rate of 250 kg Mg-1 dry tailings. Three replicate sub-plots (5 x 5 m) were planted with Agrostis capillaris cv. Highland (250 kg seed ha-1) or rooted cuttings of two Salix spp. (Salix caprea Mauerbach (BOKU 01 AT-004) and S. viminalis) and Populus nigra at a planting density of 10000 cuttings ha–1. These plots will be used during PhytoSUDOE to evaluate the benefits of implementing phytostabilization on soil biodiversity and functionality. New plots will be established in autumn 2016 and spring 2017 using Populus spp. to evaluate the effects of microbial bioinoculants on the success of phytostabilization processes. The global objective is to establish short rotation coppicing systems for biomass production.

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