Time-integrated monitoring of dioxin-like polychlorinated biphenyls (dl-PCBs) in aquatic environments using the ceramic toximeter and the CALUX bioassay

Ceramic passive samplers or toximeters (packed with active carbon 1%, w/w, on celite), in combination with the CALUX bioassay have been used as a time-integrated monitoring technique for dissolved dioxin-like PCBs in urban and industrial wastewaters. The technique showed to be reliable during laboratory experiments: (1) PCB-126 amounts extracted from the passive samplers increased linearly with the time of exposure and (2) PCB-126 concentrations calculated from the amounts accumulated by the passive samplers were in agreement with their concentrations in the testing solution. Afterwards the toximeters were applied in the field. Two sampling sites located in Egypt were chosen: the Belbeis drainage canal, and the EMAK paper mill. A total of 18 ceramic toximeters were exposed to the wastewater in both sampling sites for a maximum period of 4 weeks. Two samplers were collected weekly from each site to monitor the increase in target analytes over time. Extracts were analyzed using the CALUX bioassay and the total dioxin-like PCB toxicity was reported for the aqueous phase (water column), as well as the solid phase (sediment and sludge) in both sampling sites. The time-weighted average concentration (TWA) of dl-PCBs in wastewater of the paper mill during the sampling period ranged between 7.1 and 9.1 pg-BEQ L−1, while that of the drainage canal ranged between 9.5 and 12.2 pg-BEQ L−1. The dl-PCBs in the fibrous sludge (paper mill) and bottom sediment (drainage canal) were 0.5 and 0.4 pg-BEQ g−1 dry-weight, respectively. The organic-carbon normalized partition coefficients between sediment and water (log Koc) for the paper mill and the canal were 2.4 and 4.3, respectively.