Formation and stability of Pb-, Zn- & Cu-PO₄ phases at low temperatures: implications for heavy metal fixation in polar environments.
Low temperatures and frequent soil freeze-thaw in polar environments present challenges for the immobilisation of metals. To address these challenges we investigated the chemical forms of Pb, Zn and Cu in an Antarctic landfill, examined in vitro reaction kinetics of these metals and orthophosphate at 2 and 22 °C for up to 185 days, and subjected the products to freeze-thaw. Reaction products at both temperatures were similar, but the rate of production varied, with Cu-PO(4) phases forming faster, and the Zn- and Pb-PO(4) phases slower at 2 °C. All metal-orthophosphate phases produced were stable during a 2.5 h freeze-thaw cycle to -30 °C. Metal immobilisation using orthophosphate can be successful in polar regions, but treatments will need to consider differing mineral stabilities and reaction rates at low temperatures.
Department of Environment and Geography, Macquarie University, NSW 2109, Australia. duanne.white@canberra.edu.au
Duanne A
DA
White
Erla G
EG
Hafsteinsdóttir
Damian B
DB
Gore
Gordon
G
Thorogood
Scott C
SC
Stark
D000864:Antarctic Regions; D001110:Arctic Regions; D003300:Copper / Q000032:analysis / Q000737:chemistry; D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry*; D007854:Lead / Q000032:analysis / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D008956:Models, Chemical; D044367:Phase Transition; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D017967:Zinc Compounds / Q000032:analysis / Q000737:chemistry
D004785:Environmental Pollutants; D019216:Metals, Heavy; D010710:Phosphates; D017967:Zinc Compounds; C043952:zinc phosphate; D007854:Lead; C036682:lead phosphate; D003300:Copper