Risk assessment of a former military base contaminated with organoarsenic-based warfare agents: uptake of arsenic by terrestrial plants.

Organoarsenic-based chemical warfare agents (CWAs) such as the sternutators diphenylchloroarsine (CLARK I), diphenylcyanoarsine (CLARK II) or phenyldichloroarsine (PFIFFIKUS) still pose a notable risk in countries where former military bases that have stored these weapons have not yet been reclaimed. In fact, this is the case for many countries of Eastern Europe and the CIS. One of the most important military bases of the former Third Reich, the Heeresmunitionsanstalt I and II, is situated close to the German-Polish border at Loecknitz (Fig. 1). The German army stored and decanted different compounds of CWAs at this military base until 1945. When the Soviet Army destroyed the base in 1946, large amounts of CWAs and other organoarsenic compounds polluted the soil. Today up to 250 g (!) of arsenic may be found in 1 kg of soil at some places in this area. Since 1991, a Government Working Group has been working on the risk assessment in order to define the scope of reclamation measures. This study investigates the contamination and the uptake of arsenic by plants because little is known about the bioavailability and metabolism of sternutators and their constituents. The total arsenic concentration of nine different species of terrestrial plants with at least six samples per species is presented. In spite of the considerable arsenic contamination of the soil (mean value 923 mg arsenic/kg soil) the plant contamination remained comparably low. The median value of arsenic contamination of the above-ground organs of velvet grass, Holcus lanatus, was 0.7 mg/kg dry wt. and the mean value was 4.3 mg/kg dry wt. due to some highly contaminated samples. The highest arsenic concentration registered was 26 mg/kg dry wt. in a sample of H. lanatus, which was most probably caused by soil particles adhering to the plant. The chemical structure of the arsenic compounds carried by the above-ground plant organs has been determined by gas chromatographic investigations and showed an uptake of triphenyl arsine by the plants.