In a newly published series appearing in Environmental Toxicology and Chemistry, researchers describe the current state of the science, the challenges, and science-based best practices for modeling the influence of water chemistry on the toxicity of metals, which is a critical step in calculating protective metal concentrations in water for the protection of aquatic life.
Metals are abundant in the environment. They occur naturally and as a result of human activity. Metal levels in freshwater bodies, such as rivers and lakes, are often controlled to protect aquatic life, such as algae, zooplankton, and fish. Regulatory agencies manage metal levels by establishing numeric threshold concentrations considered acceptable to aquatic life, which can be referred to generically as protective values for aquatic life (PVALs).
There have been a number of models designed to explain the toxicity of metals to aquatic organisms by describing and predicting the conditions that influence metals toxicity, and ultimately calculate PVALs. Chris Schlekat, guest editor on the series, notes that "the scientific community agrees that bioavailability-based aquatic toxicity models are recommended for use in environmental management." Unfortunately, the development of these models has outpaced their incorporation into regulation and application for some metals, which has left some water quality regulations outdated.
The series goes on to detail considerations for model selection and model application, which will be useful for environmental professionals, managers and regulators. The models are at a state of maturity that supports their use to inform management decisions, and that will go a long way toward improving ecosystem protection.