1st Edition

Micropollutants in Large Lakes From Potential Pollution Sources to Risk Assessments

By Nathalie Chevre Copyright 2018

    Scientists, regulators, and the general public are now more and more aware of the chemicals present in surface waters worldwide. Agrochemicals, such as herbicides or insecticides, pharmaceuticals and cosmetics can be detected at low to medium concentrations in seas, groundwaters and rivers. Among freshwaters, lakes are of particular concern. These large reservoirs are used as sources of food and drinking water, but also serve for recreational activities.

    This book aims in presenting insights into the physical, chemical, and ecological dynamics of large lakes that enable proposing recommendations for sustainable lake management regarding chemicals. Lake Geneva, Switzerland, is used as a case study, but the developed methodologies and tools can be useful for lake water quality management in general.

    A first chapter is dedicated to the chemicals entering the lake through agriculture. These are mainly pesticides. After a review of the different types of compounds, the authors present the main pathways these compounds follow to enter the lake. The case of glyphosate, an herbicide largely used worldwide, is presented. A second chapter illustrates the urban source of pollutants with the case of pharmaceuticals and biocides. Two models are presented that allow estimating the load and the dynamic of these chemicals that may exit from an urban catchment and therefore reach a lake. Special attention will be paid to the ‘end of pipe’ removal of these compounds at a WWTP. A third chapter is dedicated to the lake circulation. The aim of this chapter is to present an overall description of the lake’s hydrodynamics, which is driven by three factors: wind, temperature and Coriolis forces. To achieve this aim, a hydrodynamic model is presented that allows describing the behavior of the top layer of the lake based on the wind direction. The importance of stable hydrogen and oxygen isotopes for characterizing the sources of water and the mixing processes in the lake is also described.

    The next chapters are dedicated to a Bay, called the Vidy Bay, that receives the treated effluents of the largest wastewater treatment plant of the lake catchment. This latter represents therefore one of the major point sources of contaminants for lake Geneva. These two chapters will focus on the various processes that control the transfer of chemicals (associated to particles or in a dissolved state) discharged into the bay and transported to the lake’s main water body.

    Then, a next chapter focuses on one major issue of chemicals in aquatic systems like lakes, i.e. the risk of the mixture of chemicals. The evaluation of the risk of mixture is not trivial and the models that allow doing it are presented in a critical way. Their validity as predictive tools is illustrated with the example of herbicides mixture in Lake Geneva.

    A final chapter synthesizes the main findings and discusses some recommendations for the management of large lakes regarding micropollution.

    Introduction

    Lakes as resources

    Micropollutants in surface waters: a worldwide recognition of the issue

    Book chapters

    References

    Agricultural sources of micropollutants: from the catchment to the lake

    Agricultural sources of micropollutants of the catchment

    Source and transport dynamics of glyphosate: a case study in Swiss vineyards

    Synthesis and conclusions

    References

    Urban sources of micropollutants: From the catchment to the lake

    Introduction

    Micropollutants found in urban waters

    Fate of micropollutants in WWTPs

    Conclusions

    References

    Current of Lake Geneva

    Introduction

    Wind patterns on Lake Geneva

    Hydrodynamic modeling

    Vidy Bay current patterns

    Transport of water within Lake Geneva based on the stable isotope compositional variations of water in Lake Geneva

    Summary and conclusion

    References

    Occurrence, fate and ecotoxicological relevance of micropollutants in Vidy Bay

    Introduction

    The Vidy Bay – morphology and pollution source

    Vidy Bay hydrodynamics

    Spatio-temporal occurrence of micropollutants in Vidy Bay

    Ecotoxicological risk associated to wastewater-derived micropollutants

    Dilution and degradation processes affecting micropollutant concentrations in Vidy Bay

    Modelling the micropollutants plume in the Vidy Bay

    Environmental implications

    References

    Sediment-bound contaminant transport dynamics in and around Vidy Bay

    Introduction

    Hydrodynamics within the Bay

    Contaminant path tracing and sediment focusing

    Colloid and aggregate characterization

    Vertical and lateral sedimentation pathways in Vidy Bay

    Hydrodynamic conditions of Vidy Bay’s BBL

    Conclusions

    References

    Mixture risk assessment of chemicals: from the theory to the application

    Introduction

    Mixture effect assessment theory

    Risk assessment of chemical mixtures in the Lake Geneva catchment

    Comparison with ecological data

    Conclusion

    References

    Synthesis and perspectives

    Sources of chemicals: the catchment

    Understanding lake hydrodynamics as a prerequisite for the estimation of chemical behaviour

    Behaviour of dissolved chemicals in a lake

    Behaviour of sediment-bound chemicals in a lake

    Risk assessment of the chemicals present in a lake

    References

    Biography

    Nathalie Chèvre is an ecotoxicologist, working for 15 years on environmental risk assessment of chemicals. She is an environmental engineer from EPFL and has a thesis in ecotoxicology. She worked in Montréal and Zurich (EAWAG). She is currently lecturer at the University of Lausanne. She coordinated the project Léman21 which results are presented in this book.