Evaluating the Toxicity of Perfluorooctanoic Acid and Perflorooctane Sulfonic Acid in Soil with Endogeic Geophagus Aporrectodea Caliginosa.

Evaluating the toxicity of perfluorooctanoic acid and perflorooctane sulfonic acid in soil with endogeic geophagus Aporrectodea caliginosa

Parva Zareitalabad, Jan Siemens, , Wulf Amelung, Rainer Georg Joergensen

To evaluate the ecotoxicity of PFCs on soil organisms, a microcosm experiment was set up with PFOA and PFOS at three concentration levels (1, 100, and 500 mg/kg). The soils were subjected to the activity of endogeic geophagous earthworms of the species Aporrectodea caliginosa for 40 days, using labeled with oats straw (Avena sativa L.) as carbon source. Microbial biomass C increased in the presence of the PFOA, PFOS in all of the treatments, irrespective of the applied PFOA and PFOS concentrations. In contrast, the basal respiration followed the inverse trend and produced scattered data. Also the fate of the labeled oat carbon source was not significantly influenced by the presence of PFCs, whereas soil δ¹⁵N values clearly differed among the treatments. We conclude that PFCs affect the fate of soil N more sensitively than the fate of soil C. Besides, they displayed a significant toxicity on the earthworms itself. The earthworms lost between 29 and 78% of their weight in the soils contaminated with lower PFC concentrations, but in the treatments with the highest concentration of 500mg/kg PFOA or PFOS, no earthworms survived. We conclude that faunal activity may be strongly hampered by PFC contamination, whereas overall microbial activity may even be enhanced, possibly because some organisms benefited from the death of other community members.

Keywords: A.caliginosa, PFOA, PFOS, bioindicator