Comparison of Metal Plaque Formation and Metal Accumulation in Reeds Cultured in Acid Mine Drainage Solutions and Soils

ABSTRACT

Experiments were conducted to compare the effect of citric acid (CA) on metal uptake in Phragmites australis cultured in artificial acid mine drainage (AMD) contaminated soil or aqueous solutions. When the chelator CA was present, it appeared to reduce metal plaque (i.e. Mn and Fe) formation around the roots systems of reeds; while simultaneously increasing the metal accumulation in both belowground and aboveground tissues of reeds cultured in AMD contaminated soil or solutions. Compared to soils, the effect of CA to decrease Mn and Fe plaque and enhance Mn and Fe uptake in solutions was more pronounced. In general, the more CA that was added, the more Mn and Fe accumulated in the reeds, especially the underground tissues of reeds. However, the effects of CA on Al accumulation in reeds grown in AMD soil and solutions were different. CA decreased Al plaque formation and increased Al uptake in reeds cultured in AMD contaminated soil but had no influence on Al levels in reeds grown in AMD solutions. CA could be effective at enhancing the phytoremediation of metals from AMD contaminated sites, depending on the metal levels, types of metals and the characteristics of contaminated media.

KEYWORDS:

• Acid mine drainage
• citric acid
• heavy metals
• Phragmites australis