Effect of Heavy Metals from Mine Soils on Avena Sativa L.and Education Strategies

Abstract

Heavy metals in the soils of old mining areas, besides affecting the productivity of their ecosystems, could also affect animal and human health. To test this hypothesis, we assessed the bioavailability of heavy metals to forage crops used as human food sources or components of fodder. The sites examined were the surrounding soils of two abandoned mines in Central Spain polluted with Al, Fe, Mn, and more than one of the heavy metals Zn, Pb, Cd, Cu, Cr or Ni, and As. All elements were determined by plasma emission spectroscopy with the exception of As, which was quantified by XRF. Levels of Zn, Pb, Cd, Cu and Fe were high in roots as well as in the above-ground parts of the plants, and high As levels were also found in roots. The accumulation of heavy metals by this plant was assessed in terms of its possible use for phytoremediation but also in view of its possible detrimental impacts on humans as well as wild and domestic animals. Strategies for education in areas faced with this problem are also proposed. People living in rural areas will need to be taught ecological concepts but we will also have to alert political leaders and administrators to the problem to encourage them to invest in dealing with polluted soils. In this context, it is essential to understand both the elements and processes affecting ecosystems and the perception and opinions held by the rural population of the problem of soil pollution. KEYWORDS: Ecosystems health, grasslands, agrosystems, polluted soils, phytoremediation INTRODUCTION The environment plays a major role in the health of individuals and communities, including air, water and soil, through which exposure to chemical, biological and physical agents may occur [1]. For several decades, Central Spain has sustained substantial mining activities. Although presently abandoned, the effects of these mines persist [2, 3]. The ecosystems affected by old mines are mainly grasslands consumed by cattle and sheep that are often surrounded by lands given over to forage crops, mainly barley, wheat and oats. These sites show more than one heavy metal in their topsoil layers. Thus, the heavy metals in soils of these Mediterranean ecosystems, besides affecting the productivity of the systems, could also have impacts on animal and human health. Heavy metals detected in the aerial portions of grazing and forage plant species pose a serious health risk for herbivores. Cu and Pb are both toxic with the latter being moderately toxic for plants and highly toxic for animals; Zn and Cr also have known toxic effects. This study was designed to determine the bioavailability of heavy metals to oats used as a food source or component of fodder.