Abstract
BackgroundIn situ exposure of rainbow trout up- and downstream of differently equipped wastewater treatment plants (WWTPs) and subsequent analyses of micronuclei frequencies and hepatic EROD activities were used to evaluate the impact of the effluents on fish health. Two of the facilities (WWTPs A and B) were conventional treatment plants. WWTP C has been equipped with a powdered activated carbon stage. Here, analyses were conducted prior and subsequent to this upgrade.ResultsDifferences did not only occur when comparing conventional (WWTPs A, B and C prior to the upgrade) and advanced treatment (WWTP C after the upgrade), but also between the conventionally equipped WWTPs. There was no indication for genotoxic effects or pollution-related EROD induction in fish exposed at WWTP A. In contrast, trout exposed at WWTP B expressed strong reactions. However, here, adverse reactions were also observed in fish kept upstream. Similar observations were made for EROD activities in fish exposed at WWTP C prior to the upgrade, whereas genotoxic effects could only be seen in trout kept downstream of this effluent. Upgrading of WWTP C resulted in a significant reduction of both genotoxic effects and EROD levels.ConclusionsThe results show financial investments in advanced wastewater treatment to be beneficial for aquatic ecosystems, especially when conventional technologies do not sufficiently remove pollutants. Yet, negative impacts of effluents on aquatic organisms can, under certain conditions, also be avoided by conventional treatment. Therefore, we recommend deciding on the necessity and the type of WWTP upgrading on a case-by-case basis.
Highlights
In situ exposure of rainbow trout up- and downstream of differently equipped wastewater treatment plants (WWTPs) and subsequent analyses of micronuclei frequencies and hepatic EROD activities were used to evalu‐ ate the impact of the effluents on fish health
Three to fourfold higher frequencies could be detected in blood cells of rainbow trout exposed in cages at WWTP B (Fig. 1b)
CYPIA1 activity Data regarding the EROD activities in fish exposed at WWTP C have, in parts, already been published by Maier et al [45]
Summary
In situ exposure of rainbow trout up- and downstream of differently equipped wastewater treatment plants (WWTPs) and subsequent analyses of micronuclei frequencies and hepatic EROD activities were used to evalu‐ ate the impact of the effluents on fish health. There has been an increasing public and scientific concern for the presence of micropollutants in the aquatic environment and the possibility of associated negative effects in aquatic organisms [1,2,3,4] Micropollutants, such as ingredients of pharmaceuticals, human care products, pesticides as well as industrial chemicals, are often insufficiently eliminated by conventional wastewater treatment [5, 6]. Caging of fish can help to control different parameters that might affect the subsequently analyzed biomarkers The latter are defined as biological responses induced by a chemical or a mixture of chemicals, giving a measure of exposure and/or the toxic effect [24, 25]. Such biomarkers, such as alterations in biotransformation enzyme levels, the induction of micronuclei and other abnormalities of the blood cell nuclei as well as histopathological reactions, may provide early warning sentinels for deleterious environmental and ecological effects of chemicals [26], and can be used to characterize the impact of WWTP effluents on the health status of aquatic organisms
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