Download Influence of different water saturation levels for mobility of Antimony

P12
MOBILITY OF ANTIMONY (Sb) IN SHOOTING RANGE SOIL: ROLE OF WATER
SATURATION ON FE-STABILIZED SOIL
Herzel, H.1, Okkenhaug, G.2
1
2
Institute of Geosciences, Burgweg 11, Friedrich-Schiller University, 07749 Jena, Germany
Norwegian Geotechnical Institute, P.O. Box 3930 Ullevaal Stadion, NO-0806 Oslo, Norway
e-mail: [email protected]
Shooting range soil is potentially contaminated by Sb, copper (Cu), lead (Pb) and zinc (Zn).
These elements are released due to weathering of spent bullets. The bullet core consists of
2-5 wt% Sb for getting hard lead alloys. A potential soil remediation method is to add Febased sorbents, which are good sorbents for Antimony and other metals. This may represents
a feasible stabilization of shooting range soil prior landfilling. However, common anoxic
bottom condition in the landfill may interfere with the stability of iron oxides, and a possible
subsequent release of Sb and other metals.
In our experiments the impact of different water saturation, and thus the redox conditions,
on shooting range soil stabilized with two different Fe-based sorbents was studied. Two
different water saturation levels (half and fully water saturation) were simulated for stabilized
shooting range soil from Steinsjøen in southern Norway. The soils with both 1 and 5 wt%
TOC, were treated by 2 wt% iron hydroxide and 2 wt% zero-valent iron granulate (Fe0)
respectively. The soil pore water for these different treatments is sampled at week 1, 3, 5, 8,
12 und 16 analyzed by ICP-OES (Fe, Cu, Pb and Zn) and hydride generation ICP-OES (Sb).
During the first 5 weeks of monitoring high Fe release in the iron-granulate sorbent treated
soil was observed due to incompletely oxidizing of Fe0 presumably. Much higher Fe release
in the organic rich soil under fully water saturated condition indicates reduced conditions.
This was supported by redox potential measurements (ca 200 mV). Despite the increased Fe
solubility, no increased release of Sb, Cu, Pb and Zn in any of the treatments could be
observed after 5 weeks. The experiment is still running and will continue until 16 week of
monitoring.
Fig. 1 Antimony concentration [µg/l] in pore water of organic rich shooting range soil (5 wt% organic matter)
under half and fully water saturation; treated with iron hydroxide or zero-valent iron sorbent