Monitoring of the antioxidant BHT and its metabolite BHT-CHO in German river water and ground water

The behavior of anthropogenic polar organic compounds in ground water during infiltration of river water to ground water was studied at the Oderbruch area on the eastern border of Germany. Additionally, waste water sewage treatment works (STWs) discharging their treated waste water into the Oder River and rain water precipitation from the Oderbruch area were investigated. The study was carried out from March 2000 to July 2001 to investigate seasonal variations of the target analytes. Samples were collected from four sites along the Oder River, from 24 ground water monitoring wells located close to the Oder, from one rain water collection station, from two roof runoffs, and from four STWs upstream of the Oderbruch. Results of the investigations of the antioxidant 3,5-di-tert-butyl-4-hydroxy-toluene (BHT) and its degradation product 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO) are presented. BHT and BHT-CHO were detected in all samples of the Oder River with mean concentrations of 178 and 102 ngl(-1), respectively. BHT and BHT-CHO were also detected in effluent waste water samples from municipal STWs at mean concentrations of 132 and 70 ngl(-1), respectively. Both compounds are discharged into river water directly via treated waste water. In the rain water sample, 308 ngl(-1) of BHT and 155 ngl(-1) of BHT-CHO were measured. Both compounds were detected in roof runoff with mean concentrations of 92 ngl(-1) for BHT and 138 ngl(-1) for BHT-CHO. The median values of BHT and BHT-CHO in ground water samples were 132 and 84 ngl(-1), respectively. The chemical composition of ground water from parts of the aquifer located less than 4.5 m distant from the river are greatly influenced by bank filtration. However, wet deposition followed by seepage of rain water into the aquifer is also a source of BHT and BHT-CHO in ground water.