Results of PAH screening in floodplain soils vs. soil quality standards

Abstract

A focus on soil quality issues in the EU has resulted in extensive studies aimed to development of a Soil Framework Directive, in parallel with setting up a harmonized European Soil Monitoring System. Polycyclic Aromatic Hydrocarbons (PAHs) belong to the most problematic contaminants to be monitored and controlled. This study presents the screening survey for 16 PAHs carried out in 2000 in the area severely impacted by the catastrophic flood of 1997 in the Odra River valley in Poland, Czech Republic and Germany. Within this survey, 16 PAH contents in soils due to river sediments deposition resulting from the flood, and the effect of flood on the distribution of PAHs in soils of the area were assessed in view of soil quality standards and need for remediation. The post-flood PAH spatial distribution with use of the Geographical Information System (GIS) showed distinct correlation with floodwater flow conditions, while total 16 PAH and specific compounds concentrations in the soil layer 0-0.20 m appeared to be mostly within the standard limits. In 17% of composite samples, 16PAH concentrations were found to be considerably elevated, up to the values > 1000 μg/kg exceeding the standards for agricultural soils in particular samples. PAH compounds displayed also different vertical migration potential in soils. The occurrence of the maximum PAH concentrations in the floodwater stagnation areas confirmed river sediments to be the major source of these compounds. The qualitative composition of 16 PAHs (ANty < Flth < CHR < BaA < PYR) in humus layer of soils in these areas denoted anthropogenic sources of these compounds.