A bioassessment of soil nickel genotoxic effect in orchard planted on rehabilitated coalmine overburden

Abstract

Environmental problems of non-rehabilitated overburden material are present in surrounding of open coal mines worldwide. Ecological restoration of this soil material usually deals with the improvement of its bad physico-chemical properties and its poor nutrient status, sometimes associated with heavy metal problems. Applied overburden restoration by planting orchard (1990) is assumed to be the first of its kind at opencast mines globally, so that present work was aimed at acquiring information about its efficiency of the applied measures concerning their possible use in agriculture. Various physical and chemical properties, together with the pseudo total and DTPA extractable metals (Fe, Mn, Cu, Zn, Co, Ni, Pb, Cr, Cd) as well as sequential Ni extraction analyses, was measured, in order to evaluate the impact of soil's Ni level (763-111.7 mg kg(-1)) on decreasing yields of apples, pears and plums. As a general pattern, reclaimed soil was significantly enriched with organic matter (> 2.5 percent) and nutrients compared to the initial (2 m depth) and non-reclaimed adjacent soil, approving this method for overburden restoration. Despite low Ni concentration in organs, Ni accumulation in a fruits' trees qualified these species as suitable for phytostabilization of present heavy metals, with a woody biomass as a large and important sink for Ni, especially in the roots. Applied cytogenetic studies evaluate the lack of genotoxic effect of nickel (Ni) on the gametic cells of investigated species, having no significant effect on meiosis and pollen germination. Most of the found anomalies were in apples, as a kind of aberrations with sticky figures and chromosome lagging, should be ascribed to the environmental and genetic interaction over the aging of trees.