The challenges in search of the 'Holy Grail' for protecting aquatic ecosystems from chemical pollutants

Abstract

Since 2000, I have been working on environmental quality standards for regulating and managing toxic substances in Europe and then in Hong Kong. When I engage in this research area longer and deeper, I gradually realise that there are many unresolved problems in the scientific derivation of water and sediment quality guidelines (i.e., trigger values). In this talk, I will discuss and highlight some of the major challenges in search of the Holy Grail , i.e. ecologically relevant trigger values, for protecting aquatic ecosystems from chemical pollution. First, I will examine the possible ecological impacts of toxic substances when they enter into an aquatic ecosystem. This will lead to discussion on a series of questions such as: What should we protect? , Should we protect all species? , Should we primarily focus on protection of ecological function? etc. Second, I will review and evaluate the conventional methods for determining predicted no effect concentrations (PNECs) and trigger values. In particular, I will elucidate various problems and uncertainties in using laboratory ecotoxicity data and species sensitivity distributions to derive PNECs. Third, I will argue that fundamental field-based study on ecology and biodiversity in conjunction with pollution monitoring is indispensable, as such information is vital to validate or refine the trigger values. Finally, I will suggest some possible solutions and advocate that more research effort should be made to fortify the ecological realism in derivation of the trigger value.