Acid mine drainage (AMD) endangers pomegranate trees nearby a copper mine

Abstract

Acid mine drainage (AMD) is known as an important source of environmental pollution with potentially toxic elements. High concentrations of minerals in soil were observed in a pomegranate garden nearby a copper mine, Chaharmahal and Bakhtiari, Iran. In the vicinity of this mine, AMD locally caused distinct chlorosis in pomegranate trees. As expected, potentially toxic concentrations of Cu, Fe, and Zn were accumulated in the leaves of the chlorotic pomegranate trees (YLP), i.e., increased by 69 %, 67 % and 56 %, respectively, compared to the non-chlorotic trees (GLP). Remarkably, also some other elements, including Al (82 %), Na (39 %), Si (87 %), and Sr (69 %) were considerably enhanced in YLP, compared to GLP. On the other hand, the foliar Mn concentration in YLP was strongly decreased, about 62 % lower than that in GLP. The most plausible reasons for chlorosis in YLP are either toxicity of Al, Cu, Fe, Na, and Zn, or a deficiency of Mn. In addition, AMD led to oxidative stress, shown by a high accumulation of H2O2 in YLP, and a strong upregulation of enzymatic and non-enzymatic antioxidants. AMD apparently caused chlorosis, reduced the size of individual leaves, and caused lipid peroxidation. A further analysis of the adverse effect of the responsible AMD component(s) could be helpful to reduce the risk of food chain contamination.