Small scale variability of chlorinated POPs in the river Elbe floodplain soils (Germany).

The long-time use of persistent organic pollutants (POPs) led to a world-wide contamination of environmental compartments. Although, bans of numerous POPs reduced the POP input to rivers. Floodplain soils are still highly contaminated, because they are sinks for these compounds, which restrict their agricultural use. Hence, the intention of this study was the determination of 29 relevant POPs in two soil depths (0-10 cm and 10-20 cm) of a field experiment to get a survey on the small-scale spatial variability of the experimental site and to establish a baseline for phytoremediation experiments. The POP concentrations ranged from 0.1 microg kg(-1) to 160 microg kg(-1) and showed an increase of dieldrin, endrin, endosulfan I, endosulfan II, heptachlor, p,p'-DDE, o,p'-DDE and methoxychlor concentrations on average in the river Elbe floodplains between the years 1998 and 2007. However, there was a pronounced small-scale spatial variability of POP concentrations in vertical and horizontal direction. The latter was estimated by comparing the relative standard deviations (RSDs) of the POP concentrations in sample sets located at sites of increasing distance from <1m to >10000 m.