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Abstract:

Mining spoil heaps, as a remnant of extensive mining activity in many parts of the world, are considered as a serious contaminated site especially due to the high content of potentially toxic elements (PTEs) and acidic soil pH which also inhibits the development of vegetation cover. The aim of our paper was to experimentally test the effectiveness of natural sorbents (biochar, bentonite, organo-zeolitic substrate 1 – 20 wt%, chicken manure) on pH technosol taken from two abandoned mining localities - Cu mine waste dump Maximilián (Slovakia) and Fe – Cu sulphide mine waste dump Libiola (Italy) and their impact to the support of grass mixture growth. We evaluated the height of plants, the weight of fresh aerial biomass and dry matter. Testing of the effectiveness of individual sorbents was performed by a pot experiment. The results showed that all tested sorbents statistically significantly (P < 0.001) increase the pH from technosols initially strong to ultra-acid (Maximilian heap – pH 5.17; Libiola – 3.42), which statistically significantly supports the development of vegetation cover (P < 0.05 – 0.001). The growth of aboveground biomass is significantly more effective in a weakly acidic soil reaction (pH 6.5 – 6.7). However, the choice of sorbent depends on the character of the geological basement and the properties of technosol on its surface. Organo-zeolitic substrate was the most effective for ultra-acid soil from Libiola, influenced by oxidation of the basalt- and serpentinite-hosted Cu-ores. On the other hands, bentonite was proved as the most useful on Maximilián heap with much more acidic geological basement built by siderite, tetrahedrite and chalcopyrite. This knowledge can be used in practice in the ecological restoration of surfaces of disturbed mining or other toxic soils.