Mj. La Force et al., Redistribution of trace elements from contaminated sediments of Lake Coeurd'Alene during oxygenation, J ENVIR Q, 28(4), 1999, pp. 1195-1200
Sediments of Coeur d'Alene Lake in northern Idaho are contaminated with hea
vy metals as a result of mining in the Coeur d'Alene River basin. Dredging
and disposal operations have been suggested as a possible means of environm
ental remediation; thus, detailed knowledge is required as to how sediment
oxygenation can result in the redistribution of trace elements. To simulate
changing physicochemical soil conditions, stirred batch experiments were c
onducted using fresh sediment core material retrieved from the lake, Fifty
grams of sediment were added to 750 mL of double deionized water and mixed
while being oxygenated for 260 h. The following parameters were monitored a
s a function of time: pH and E-h, contaminant trace element release into th
e aqueous phase, and metal abundance within operationally defined fractions
of the solid phase: magnesium chloride (exchangeable), sodium hypochlorite
(organic), sodium acetate-acetic acid (carbonate), ammonium oxalate in the
dark (non-crystalline), hydroxylamine hydrochloride (crystalline), and pot
assium perchlorate-hydrochloric-nitric acid (sulfidic) extractable sediment
fractions. In all trials, levels of aqueous-phase Zn remained high through
out the simulations (6.60 mg L-1) and were highly correlated (sigma value =
0.95) with Mn. Oxygenation and disturbance resulted in a shift in trace el
ement partitioning from the sodium hypochlorite (organic) and potassium per
chlorate-hydrochloric-nitric acid extractable (sulfidic) fractions into the
ammonium oxalate in the dark (non-crystalline) extractable fraction. Overa
ll, these results indicate that oxygenation and agitation of anaerobic sedi
ment results in Zn release into solution with concomitant redistribution of
trace elements in the solid-phase.