Heavy metals compounds from tailing pond sludge and their distribution to the tissues of the selected common Poaceae species and crop plants

Abstract

This study deals with the issue of contaminant transfer from a tailings pond (Rosina- Žilina, Slovakia) to the surrounding environment. More than one hundred samples of soil and plant tissues were taken. Analysis focused to two species of the Poaceae family (Phragmites australis and Calamagrostis sp.) as well as common crops (corn, apple, cherry) in the vicinity of the tailings pond. All samples were analysed by x-ray spectrometry for rapid and accurate measurements in situ as well as in laboratory conditions. We assessed the risk of ash-waste contamination to the ecosystem during transfer and the related potential threat to human health long term. Arsenic content in soil samples of ash material ranged from 41 to 91 ppm, but these values did not confirm the transfer of this element into the tissues of monitored plants. Mercury levels were only detected in samples from the tailings pond where mean values in soil and stems and blooms were equal. The presence of lead in soil samples and plant tissues was also detected. The data obtained indicates possible bioaccumulation of lead, especially in Calamagrostis sp.. Soil samples from tailings pond contained a mean of 36 ppm of lead and individual measured tissues of Calamagrostis sp. contained lead levels of 13 to 18 ppm. These findings support the hypothesis that heavy metals are bio-avalible via the food chain, especially for herbivores. Heavy metals in investigated crops did not differ between sample sites. Corn leaves were more polluted than kernels, while fruit seeds were more polluted than pulp or leaves.