Résumé - Abstract
Emerging contaminants (ECs) include new compounds that are created recently. The term can also refer to legacy contaminants with renewed understanding of risks, or long-existing substances with newly identified environmental impacts. Mining activities can lead to the release and transformation of a range of contaminants that accumulate in groundwater, surface water and surrounding soils. Many of these contaminants are toxic to humans and other aquatic organisms including microorganisms, plants, invertebrates and vertebrates. ECs at mine sites include various heavy metals (e.g., vanadium, molybdenum, and thallium) and metalloids (e.g., selenium and antimony), inorganic industrial compounds and by-products (e.g., perchlorate and thiocyanate), and a variety of emerging organic contaminants (EOCs) (e.g., PFASs, flame retardants, pharmaceutical compounds, and personal-care products). The focus of this study is to further review a series of hydrogeochemical processes that control ECs in consideration of geologic, hydrological and geochemical processes. The geological processes (metal(loids) particularly) relate to the geological characteristics of mine sites. Petrologic abundance mainly affects the fate of emerging metal(loids), since they have natural sources in ores and minerals while other emerging contaminants are usually anthropogenically sourced. Geological characteristics of mine sites can affect the fate of all the emerging contaminants, including the level of confinement and the hydraulic properties of the underlying aquifers and overlying soils. Various hydrological processes include precipitation, infiltration, seepage dilution etc., either naturally or anthropogenically induced, that can control the migration of ECs in surface water and groundwater. Geochemical processes that impact the fate of metal(loid)s include mineral dissociation which induces the release of metal(loid)s, redox transformation refers to the valence alteration of metal(loid)s that controls their dissolution or precipitation and adsorption/desorption to/from natural adsorbents, such as clay and metal oxides, both of which can either retard or facilitate their transport. In terms of perchlorate, thiocyanate and EOCs, microorganism induced chemical transformation and possibly adsorption are the major processes that control their degradation and migration. Future research will lead to on-site investigation of the occurrence of ECs at mine sites in Canada. Both groundwater and surface water will be sampled for laboratory detection and analysis of ECs.