Search

The long-term activity of a polymetallic ore mine in the region of Tarniţa-Suceava, Romania, has resulted in an enormous amount of waste material, collected in tailing dumps and ponds. The impact of the waste materials on the surrounding ecosystem and human health are far to be fully estimated. The deposited waste has exerted negative impact on the environment, especially on the soils that host dumps and drainage waters. Heavy metals, including arsenic also interfere with the metabolism of plants, and reduce the nutritive value of the produce. Consequently, we applied several chemical analyses and germination tests in an attempt to estimate the ability of soil to maintain the plants growing, the bioavailability, and heavy metals uptake. Copper, zinc, arsenic, and lead were the most abundant toxic elements in the studied samples. The sequential extraction revealed that up to 51% of copper was retained by amorphous and crystalline iron oxides in soil. The heavy metal concentration in river water during dry season varied from 0.13 mg/L (Fe) to 4.2 mg/L (Zn), being below the maximum contamination level for drinking water. The seeds germinated on the studied soils accumulated elevated concentrations of heavy metals thus indicating the bioavailability of soil contaminants. Arsenate decreased significantly the germination rate of wheat seeds, but phosphate has proved antagonistic. Germination tests may also be a reliable tool in the investigation of toxicity of waste materials to the environment. Decontamination methods based on salt extraction in water and some solutions are discussed as well. [ABSTRACT FROM AUTHOR]

Heavy-metal pollution of forest soils around closed mines represents an important environmental concern and we measured the contamination level in the forest plants. The waste material generated by the now-abandoned ore-processing plant of Tarnița-Suceava, Romania, situated in the Eastern Carpathians, contain large amount of heavy metals, aluminum, and arsenic. The high risk of environmental contamination of sterile dumps is amplified by their susceptibility to airborne, hydromechanical and hydrochemical transport. In the investigated area, the topography, soil, vegetation, hydrology, fauna, microclimate and landscape were much altered or even destroyed. After careful experiments at the laboratory level, we have proposed some chemical remediation and bioremediation methods, which can be used both in Romania and abroad. This research relies thus on eco-friendly methods for heavy metals removal from contaminated forests with mining waste. First of all, we determined the high concentrations of Cu, Fe, Pb, Zn, Ba, and As, and observed that they affect much the germination of wheat seeds used here as an indicator of toxicity. Moreover, the germination of Triticum aestivum L. was even interrupted by sterile dump material, which is highly concentrated in copper and arsenic. The yeast-based decontamination of soil containing high amounts of heavy metals and arsenic, originated from a sterile dump of Tarnita-Suceava, Romania, was then studied among other bioremediation methods. However, yeast (Saccharomyces cerevisiae) succeeded to retain only partly heavy metals and arsenic from soil extracts. By our opinion, the high amounts of metalic contaminants should be first removed by chemical ways for example by precipitation at pH 12 (out of contaminated site), filtration or centrifuging and then neutralization of filtrate/supernatant to pH 6-7. Electrolysis could be also used to recover precious or harmful metals. Therefore, in this particular case the ex situ chemical decontamination with alkaline solutions in order to hinder further and continuous contamination of soil and natural waters by the waste huge deposits should be followed by some mild bioremediation procedures able to remove in due time almost all the metal ions found in great excess around the barite and copper closed mines. [ABSTRACT FROM AUTHOR]