RAMIRAN International ConferenceThe São Domingos mining area is located in the Iberian Pyrite Belt, SE Portugal, and represents a serious
environmental hazard (Matos and Martins, 2006). Exploitation dated back to pre-roman and roman times with
extraction of Ag, Au and Cu exploitation, mainly in the gossan (resulting from the ore weathering). The intense
exploitation started in the middle of 19th century, both in the gossan and sulfide ore-containing Cu, Zn, As and Pb,
and lasted until 1960, with the exhaustion of the ore (Quental et al., 2002). Different types of waste materials were
left: gossan, host rocks (volcanic with shales, and shales), roman and modern slags, smelting ashes and brittle and
blocks of pyrite (Matos, 2004; Álvarez-Valero et al., 2008). All sulfide mine wastes are typically heterogeneous and
contain high amounts of trace elements, acidic pH and small contents of organic matter and nutrients. The large
dumps containing pyrite and other metal sulfides generate, by oxidation, acidic mine drainage (AMD) which
increases the availability of trace elements for microorganisms and plants in the surrounding soils. All of these
characteristics contribute towards a system that is barely capable of supporting the establishment or survival of
plants.
The use of amendments and spontaneous colonization (vegetation) from mining areas (phytostabilization)
are cost-effective and environmentally sustainable methods to rehabilitate these contaminated and degraded areas
even in arid and semi-arid conditions (Tordoff et al., 2000; Mendez and Maier, 2008). Thus, the preparation of
Technosols from mixtures of organic and inorganic wastes can be an attractive option to rehabilitate mining areas
because they can improve physical, chemical and biological properties contributing, at the same time, towards a
strategy of wastes valorisation (Macías, 2004). The use of mixtures composed of residues with different C:N ratios
can be used to manipulate the rate of mineralization. Nevertheless, the amendments used should also promote other
soil functions (Arbestain et al., 2008). The objective of this study was to evaluate the influence of cost-effective
organic and inorganic amendments, available in the region, in the rehabilitation of sulfide materials from the São
Domingos mine are
