Metal transport and remobilisation in a basin affected by acid mine drainage: the role of ochreous amorphous precipitates.

Metal-polluted mine waters represent a major threat to the quality of waters and sediments in a downstream basin. At the confluence between acidic mine waters and the unpolluted waters of the Gromolo Torrent (Liguria, North-West Italy), the massive formation of an ochreous amorphous precipitate takes place. This precipitate forms a soft blanket that covers the torrent bed and can be observed down to its mouth in the sea. The aim of this work is to evaluate the dispersion of metals in the Gromolo Torrent basin from the abandoned Cu-Fe sulphide mine of Libiola to the Ligurian Sea and to assess the metal remobilisation from the amorphous precipitates. The mineralogy of the superficial sediments collected in the torrent bed and the concentrations of different elements of environmental concern (Cu, Zn, Cd, Co, Cr, Mn, Ni, Pb, As, and Sb) were therefore analysed. The results showed that the precipitates contain high concentration of Fe, Al, Cu, and Zn, significantly modifying the bulk chemistry of the Gromolo Torrent sediments. In order to evaluate the possible remobilisation of ecotoxic elements from the amorphous precipitates, bulk leaching tests were performed with both deionised and seawater. Bulk leaching tests with deionised water mobilised primarily high Pb amounts, but also relatively high concentrations of Fe, Al, Cu, and Zn are released in the leachate. In seawater tests, Fe, Al, Cu, and Zn were released in smaller amounts, while other elements like Mn, Cd, Co, and Ni increased in the released fraction. Pb was still strongly released as in deionised water experiments. The results show that the interaction of precipitates and seawater can remobilise high concentrations of metals, thus affecting the surrounding environment.

Microfungi in highly copper-contaminated soils from an abandoned Fe-Cu sulphide mine: growth responses, tolerance and bioaccumulation.

Copper is one of the most dangerous soil contaminants. Soils affected by high copper concentrations show low biodiversity and, above all, inadequate environmental quality. Microorganisms such as fungi can play a key role in metal-polluted ecosystems via colonization and decontamination. The study is devoted to characterize the microfungal community in highly Cu-contaminated bare soil from derelict Fe-Cu sulphide mines and to isolate microfungal strains able to tolerate and accumulate Cu. 11 Different taxa to be isolated has been isolated during two sampling campaigns (in Autumn and in Spring). Among these, Clonostachys rosea, Trichoderma harzianum, and Aspergillus alliaceus were tested at increasing Cu(II) concentrations and showed a Cu(II)-tolerance capability ranging from 100 to 400 mg L(-1). Moreover, the strains of T. harzianum and C. rosea presented a high Cu(II)-bioaccumulation capability, 19628 and 22,222 mg kg(-1), respectively. These microfungi may be fruitfully exploited in mycoremediation protocols.