Spatial and Temporal Presence of a Wastewater-Derived Micropollutant Plume in Lake Geneva

Abstract

This study discusses the occurrence and environmental risk associated with a micropollutant plume originating from the direct discharge of treated wastewater into the Vidy Bay of Lake Geneva, Switzerland. The temporal variations and spatial extent of the plume and its effect on the presence of 39 pharmaceuticals and other micropollutants in the Vidy Bay were assessed over a 10 month period. A pronounced plume was observed from April to October, leading to locally elevated (up to 70-fold) pharmaceutical concentrations compared to the surrounding water column. For three of the measured substances, these plume-associated concentrations were sufficiently high to pose an ecotoxicological risk. The plume depth followed the thermal lake stratification, which moved to lower depths over the course of the warm seasons. Pharmaceutical hotspots associated with the plume were detected as far as 1.5 km downstream of the effluent wastewater outfall, but concentrations typically decreased with increasing distance from the wastewater outfall as a result of dilution and photodegradation. From November to January, when uniform temperature prevailed throughout the water column, no micropollutant plumes were detected. In contrast to pharmaceuticals, most pesticides showed homogeneous concentrations throughout the Vidy Bay during the whole study period, indicating that the effluent wastewater was not their dominant source. A strong linear correlation between electrical conductivity and concentrations of wastewater-derived micropollutants was identified. This relation will allow future estimates of wastewater-derived micropollutant concentrations via simple conductivity measurements.

Photochemical Fate of Carbamazepine in Surface Freshwaters: Laboratory Measures and Modeling

“…Chemical transformation not involving light, gas partitioning and sedimentation could be excluded (the latter because CBZ is polar and rather hydrophilic), 50 while biotransformation seems little likely for CBZ. 2,51 With data relevant to the epilimnion of Lake Greifensee (5 m depth, 0.1 mM nitrate, 3.5 mg C L −1 DOC, 2 mM bicarbonate, 10 µM carbonate 14,52 ) and Table 1 . This value is very near the field rate constant of CBZ attenuation after exclusion of the outflow, and suggests that photochemistry could play a role in the loss of CBZ in Lake Greifensee epilimnion.…”

Treatment of micropollutants in municipal wastewater: Ozone or powdered activated carbon?

“…Uncertainties of the micropollutant analyses, including recovery and repeatability uncertainties, were compound-and concentration-dependent with a decreased reproducibility close to the limit of detection (LOD). For the large majority of the compounds, the relative standard deviation was < 30% (Bonvin et al, 2011). Compounds detected with this method are presented in Table 2 (analytical method A) with their respective LODs.…”

Wastewater as a point source of antibiotic-resistance genes in the sediment of a freshwater lake

“…In contrast, site NC14 near the Chamberonne river mouth showed elevated ARG levels (Figures 3a, b and f). Previous studies monitoring pollutant transport in the water column (Wildi and Rossi, 1997;Goldscheider et al, 2007;Haldimann, 2009;Bonvin et al, 2011) document that at least under certain circumstances site NC13 might be affected by contaminants released from the WWTP, including ARGs (Czekalski et al, 2012). However, the Chamberonne river is known as a discontinuous source of fecal bacteria (Haldimann, 2009;Haller et al, 2009), whereas its THg load is too low to explain elevated concentrations measured in sediments of Vidy Bay (Howa and Vernet, 1988).…”

“…The bay's sediments have been reported to be heavily polluted by fecal-indicator bacteria, heavy metals, nitrogen and phosphorus (Poté et al, 2008). Micropollutants, including antibiotics (Bonvin et al, 2011), as well as multiresistant bacteria and ARGs pass through the WWTP and are subsequently discharged in considerable amounts into Vidy Bay (Czekalski et al, 2012). Low levels of multiresistant bacteria and ARGs were found even 3.2 km from the WWTP discharge pipe, where lake water is pumped for drinking water production (Czekalski et al, 2012).…”