Effects of acidification on mobilization of heavy metals and radio nuclides from sediments of a fresh water lake
Schindler, D.W.; Hesslein, R.H.; Wagemann, R.; Broecker, W.S.
Canadian Journal of Fisheries and Aquatic Sciences 37(3): 373-377
ISSN/ISBN: 0706-652X Accession: 005287648
Large (10 m) diameter enclosures were sealed to the sediments in 2-2.5 m of water in Lake 223. Two tubes were held at control pH (6.7-6.8), one was lowered to pH 5.7 and one to pH 5.1, using H2SO4. Al, Mn, Zn and Fe were released from lake sediments at pH 5 and 6. Concentrations of Zn in the overlying water column exceeded 300 .mu.g .cntdot. l-1. Radioisotopes of several heavy metals added to the water of the enclosure showed the following: all metals were removed from the water at log-linear rates, with half-times of 5-25 days. Acidification caused several metals to become more soluble, including 59Fe, 60Co, 54Mn and 65Zn. Solubility of 48V and 203Hg decreased with increasing acidity. Acidification also slowed the loss to sediments of 54Mn and 65Zn. Losses of 133Ba, 75Se, 134Cs and 48V were more rapid under acid conditions. The fractions of any isotope retained by a 0.45 .mu.m filter, activated charcoal and mixed-bed ion exchange resin remained constant throughout the experiment at any given pH.