The wastewater micropollutant carbamazepine in insectivorous birds-an exposure estimate

Abstract

Insects with aquatic life stages can transfer sediment and water pollutants to terrestrial ecosystems, which has been described for metals, polyaromatic hydrocarbons, and polychlorinated chemicals. However, knowledge of the transfer of aquatic micropollutants released by wastewater treatment plants is scarce despite some preliminary studies on their occurrence in riparian spiders. In our study, we address a major analytical gap focusing on the transfer of the micropollutant carbamazepine from the larvae to the adult midges of Chironomus riparius using an optimized QuEChERS extraction method and HPLC-MS/MS applicable to both life stages down to the level of about three individuals. We show that the uptake of carbamazepine by larvae is concentration-dependent and reduces the emergence rate. Importantly, the body burden remained constant in adult midges. Using this information, we estimated the daily exposure of insectivorous tree swallows as terrestrial predators to carbamazepine using the energy demand of the predator and the energy content of the prey. Assuming environmentally relevant water concentrations of about 1 μg/L, the daily dose per kilogram of body weight for tree swallows was estimated to be 0.5 μg/kg/day. At places of high water contamination of 10 μg/L, the exposure may reach 5 μg/kg/day for this micropollutant of medium polarity. Considering body burden changes upon metamorphosis, this study fills the missing link between aquatic contamination and exposure in terrestrial habitats showing that wastewater pollutants can impact birds' life. Clearly, further analytical methods for biota analysis in both habitats are urgently required to improve risk assessment.

Keywords: Body burden; Chironomus riparius; Habitat transfer; Metamorphosis; QuEChERS.

Fig. 1

a Internal concentrations and emergence rates: emergence rate in % and internal carbamazepine concentration for larvae and adult midges (ng/g wet weight) depending on the nominal concentration of carbamazepine in the exposure medium. Biota samples were extracted with the optimized QuEChERS method and quantified by HPLC–MS/MS in two independent workups (see the “Materials and methods” section). b, c Comparison of internal concentrations and body burden: b Exponential fit of internal concentrations in larvae and adult midge tissue extracts (average values in a). The results of the two replicates and two measurements each are given for each concentration level. c Body burden of carbamazepine in ng per individual larvae and adult midge, data from a, based on the average mass of 2 mg (adult midges) or 6 mg (larvae)