2018-04, Ji, Ying, Vollenweider, Pierre, Lenz, Markus, Schulin, Rainer, Tandy, Susan

Antimony (Sb) contamination of soils is of concern due to human activities such as recycling of Sb containing Pb acid batteries, shooting and mining. However Sb uptake by plants is poorly documented, especially when plants are growing on waterlogged soils and iron plaques form on their roots. The effect of iron plaques on Sb uptake has been investigated in rice, but not so far in other plants. Here, rye, ryegrass, wheat and meadow fescue were induced to form iron plaques and then exposed to antimonite (Sb(III)) or antimonate (Sb(V)) under hydroponic conditions. In the Sb(III) treatment, although iron plaques adsorbed Sb(III), this did not affect root and shoot Sb concentrations of plants. In the Sb(V) treatment, iron plaques adsorbed Sb(V) to a lesser extent than for Sb(III), although it was still significant in all plants but wheat. Iron treatments also significantly increased root Sb concentrations of fescue while they significantly decreased shoot Sb concentrations in rye, ryegrass and fescue. This may be due to other factors as well as antimony adsorption to iron plaques.

2015-09, Hockmann, Kerstin, Tandy, Susan, Lenz, Markus, Reiser, Rene, Conesa, Hector, Keller, Martin, Studer, Björn, Schulin, Rainer

Many soils polluted by antimony (Sb) are subject to fluctuating waterlogging conditions; yet, little is known about how these affect the mobility of this toxic element under field conditions. Here, we compared Sb leaching from a calcareous shooting range soil under drained and waterlogged conditions using four large outdoor lysimeters. After monitoring the leachate samples taken at bi-weekly intervals for >1.5 years under drained conditions, two of the lysimeters were subjected to waterlogging with a water table fluctuating according to natural rainfall water infiltration. Antimony leachate concentrations under drained conditions showed a strong seasonal fluctuation between 110 μg L−1 in summer and <40 μg L−1 in winter, which closely correlated with fluctuations in dissolved organic carbon (DOC) concentrations. With the development of anaerobic conditions upon waterlogging, Sb in leachate decreased to 2–5 μg L−1 Sb and remained stable at this level. Antimony speciation measurements in soil solution indicated that this decrease in Sb(V) concentrations was attributable to the reduction of Sb(V) to Sb(III) and the stronger sorption affinity of the latter to iron (Fe) (hydr)oxide phases. Our results demonstrate the importance of considering seasonal and waterlogging effects in the assessment of the risks from Sb-contaminated sites.