Growth and absorbance of heavy metals of reed plants ( Phragmites australis ) in soil after mineral mining in Thai Nguyen province of Vietnam

摘要

Reed plant ( Phragmites australis) is an indigenous and wild plant species which was found as a pioneer plant appearing in many places after mineral mining in Thai Nguyen province of Vietnam. This plant has the capacity to uptake heavy metals in soil so that it is considered to be a good biological control method in contaminated soils. The study was conducted to survey five (5) different places after mineral mining in Thai Nguyen such as Tr?i Cau iron mine, Lang Hich lead-zinc mine, Muoi Nac lead-zinc mine, Cay Cham titanium mine 1 and Cay Cham titanium mine 2. The results showed that reed is a pioneer plant and appears in different topographical conditions from catchment areas to slope shoulder. However, dense plant populations were found in lower places with high soil moisture contents. Due to long mineral mining process, the topsoil has been shuffled, causing effects on the growth and the population distribution of plants. High contents of heavy metals were accummulated in reed plant body as follows: Zn 1154.66 mg/kg ; Pb 243.92 mg/kg , Cd 35.84 mg/kg , and As 1 99 . 02 mg/kg . The accumulation of heavy metals in reed plant is proportional with the contents of heavy metals in soil and inversedly correlational with pH and organic carbon content in the soil. It is recognized that reed plants play an enormous role in absorbing heavy metals and in keeping the soil free from pollutants after mining.