PCDD/F and dioxin like PCB profiles in soils amended with sewage sludge, compost, farmyard manure and mineral fertilizer since 1962

In a long-term field experiment established in 1962 we investigated the influence of the application of biowaste derived fertilisers such as sewage sludge (SSL), compost (COM) and farmyard manure (FYM) to a luvisol derived from loess on the contents of PCDD/F and dioxin-like PCB (DL-PCB). 39 years of experimental SSL and COM applications exceeding 4 times the maximal amount as laid down in German legislation resulted in a doubling of the I-TEQ budget for PCDD/F and a 3 fold increase for DL-PCB as compared to test plots amended with mineral fertilizer (MIN) only. As compared to MIN the application of FYM had no effect on the PCDD/F and PCB content in soil. The average contribution of the DL-PCB to the WHO-TEQ were 19% in the MIN and FYM plots and somewhat higher in the COM (23%) and in the SSL (27%) plots. Although the test plots received 4 times the maximum application of SSL as laid down in the German SSL ordinance, and the investigated region represents the upper end of the topsoil concentrations typically found in Germany, the soils treated with SSL and COM were still a factor of 4 below the German guideline value of PCDD/F for arable land. No enhancement of translocation of PCDD/F and PCB into the corresponding sub-soils due to the presence of dissolved humic matter or other surfactants was observed in the treatments with the different kinds of biowaste. The similarity of congener patterns in all soils, irrespective of the type of fertilizer applied, points towards atmospheric deposition of PCDD/F and DL-PCB as the main intake route in the soils. Moreover, in the case of the SSL and COM plots additional atmospheric deposition from other locations was concentrated and focussed into the amended soils. It is concluded that the common practice of SSL applications in Germany does not pose a current threat to the agro-environment what regards PCDD/F and DL-PCB. However, time trend data on PCDD/F in SSL-amended soils will be needed to obtain a prognosis about the long term effect of biowaste applications on soil quality.

JRC.DDG.H.5 - Rural, water and ecosystem resources