Combination of In Situ Feeding Rate Experiments and Chemical Body Burden Analysis to Assess the Influence of Micropollutants in Wastewater on Gammarus pulex.

Sarah Könemann,Pedro Inostroza,Sabrina Schiwy,Ira Brückner,Johannes Pinnekamp,Yvonne Müller,Daniel Tschentscher,Martin Krauss,Henner Hollert

doi:10.3390/ijerph16050883

Abstract

Wastewater discharge is one of the main sources of micropollutants within the aquatic environment. To reduce the risks for the aquatic environment, the reduction of the chemical load of wastewater treatment plant effluent is critical. Based on this need, additional treatment methods, such as ozonation, are currently being tested in several wastewater treatment plants (WWTPs). In the present study, effects were investigated using in situ feeding experiments with Gammarus pulex and body burden analyses of frequently detected micropollutants which used a Quick Easy Cheap Effective Rugged and Safe (QuEChERS) multi-residue method to quantify internal concentrations in collected gammarids. Information obtained from these experiments complemented data from the chemical analysis of water samples and bioassays, which predominantly cover hydrophilic substances. When comparing up- and downstream feeding rates of Gammarus pulex for seven days, relative to the WWTPs, no significant acute effects were detected, although a slight trend of increased feeding rate downstream of the WWTP Aachen-Soers was observed. The chemical load released by the WWTP or at other points, or by diffuse sources, might be too low to lead to clear acute effects on G. pulex. However, some compounds found in wastewater are able to alter the microbial community on its leaves, leading to an increase in the feeding rate of G. pulex. Chemical analysis of internal concentrations of pollutants in the tissues of collected gammarids suggests a potential risk for chronic effects with the chemicals imidacloprid, thiacloprid, carbendazim, and 1H-benzotriazole when exceeding the critical toxic unit value of −3. This study has demonstrated that a combination of acute testing and measurement of the internal concentration of micropollutants that might lead to chronic effects is an efficient tool for investigating river systems, assuming all relevant factors (e.g., species or season) are taken into account.

Highlights

In recent years, the occurrence of emerging contaminants in the aquatic environment has increasingly been reported by the scientific community and has become an environmental issue of global concern [1,2,3]
Since the exact composition of wastewater treatment plants (WWTPs) effluents is predominantly unknown and can vary over time, and chemical analysis requires a substantial amount of a priori knowledge about the substances that could be present, in vivo, in vitro, and in situ effect-based methods (EBMs) should be used to complement chemical analysis in ecotoxicological risk assessment [10,11]
In order to evaluate the effects of wastewater on the shredder performance of G. pulex, the feeding rates at all sampling sitesthe were compared to each other

Summary

Introduction

The occurrence of emerging contaminants in the aquatic environment has increasingly been reported by the scientific community and has become an environmental issue of global concern [1,2,3]. Micropollutants commonly occur at trace concentrations in the lower μg/L or ng/L range [5] These low concentrations in combination with suspected low toxic effect concentrations and the large variety of micropollutants that are likely to be released into the environment leads to increased efforts needed for detection and chemical analysis and challenges current drinking water and wastewater treatment processes [6]. In industrialized countries, such as Germany, more than 90% of incoming wastewater is treated in centralized wastewater treatment plants (WWTPs) [5]. Since the exact composition of WWTP effluents is predominantly unknown and can vary over time, and chemical analysis requires a substantial amount of a priori knowledge about the substances that could be present, in vivo, in vitro, and in situ effect-based methods (EBMs) should be used to complement chemical analysis in ecotoxicological risk assessment [10,11]

Objectives

Methods

Results

Discussion

Conclusion