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Integrating laboratory and field studies to assess impacts of discharge from a uranium mine and validate a water quality guideline value for magnesium.
Trenfield, Melanie A; Harford, Andrew J; Mooney, Thomas; Ellis, Mark; Humphrey, Chris; van Dam, Rick A.
Afiliação
  • Trenfield MA; Environmental Research Institute of the Supervising Scientist, Darwin, Australia.
  • Harford AJ; Environmental Research Institute of the Supervising Scientist, Darwin, Australia.
  • Mooney T; Environmental Research Institute of the Supervising Scientist, Darwin, Australia.
  • Ellis M; Environmental Research Institute of the Supervising Scientist, Darwin, Australia.
  • Humphrey C; Environmental Research Institute of the Supervising Scientist, Darwin, Australia.
  • van Dam RA; Environmental Research Institute of the Supervising Scientist, Darwin, Australia.
Integr Environ Assess Manag ; 15(1): 64-76, 2019 Jan.
Article em En | MEDLINE | ID: mdl-30207049
ABSTRACT
Magnesium (Mg) is a primary contaminant in mine water discharges from the Ranger Uranium Mine (north Australia). Site-specific water quality guideline values (WQGVs) for Mg have been derived from laboratory and field studies. Contaminated groundwater with elevated electrical conductivity and metals (Mg, Mn, U, SO4 , and Ca) was detected flowing from the mine site into adjacent surface waters. This provided an opportunity to investigate the protectiveness of the Mg WQGV by conducting an integrated laboratory and field study. A direct toxicity assessment (DTA) of the groundwater was conducted with local tropical freshwater species duckweed (Lemna aequinoctialis), green hydra (Hydra viridissima), and the aquatic snail Amerianna cumingi. An in situ toxicity assessment was carried out in the creek receiving diluted groundwater by use of the same species of snail, to aid interpretation of laboratory-derived data. The toxicity of the contaminated groundwater was higher than Mg-only toxicity testing for H. viridissima, with other elevated metals and major ions contributing to toxicity. However, for duckweed and snail, the contaminated groundwater was less toxic than the Mg-only testing. In situ snail monitoring supported laboratory exposures, showing no effect on reproduction of A. cumingi exposed to an average of approximately 5 mg/L Mg; however, a very small effect was noted closer to the groundwater source, probably associated with other contaminants. The minimal toxicity observed for L. aequinoctialis and A. cumingi, despite the elevated Mg, can be explained by the high calcium (Ca) concentration of the water and the potential amelioration of metal toxicity. The extent of Ca amelioration of Mg toxicity was organism dependent. This study affirms the proposed environmental rehabilitation standard of 3 mg/L Mg for surface waters with a Ca concentration typical of water from this mine site. Integr Environ Assess Manag 2019;1564-76. © 2018 SETAC.
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Texto completo: 1 Base de dados: MEDLINE Assunto principal: Poluentes Radioativos da Água / Urânio / Magnésio Idioma: En Ano de publicação: 2019 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Poluentes Radioativos da Água / Urânio / Magnésio Idioma: En Ano de publicação: 2019 Tipo de documento: Article