Abstract
In Norway, mine tailings waste can be deposited by coastal submarine dispersal. Mine tailings slurry includes fine particles <10 µm with elevated levels of metals (e.g., copper, iron) from residual mineral ore. Prolonged suspension of small particles in the water column may bring them into contact with locally spawned pelagic fish eggs, including Atlantic cod, Gadus morhua. Newly fertilized cod embryos were exposed to suspended mine tailings particles up to 3.2 mg/L in flow‐through aquaria for a total of 21 d. Significantly more particles adhered to the surface of the chorion from the high treatment after 11‐d exposure, and dissolved Cu concentrations increased in the water (up to 0.36 ± 0.06 µg/L). There was no adverse effect on embryo mortality but an 8% elevation in larval mortality. There were no differences with treatment on timing of hatching, embryo and larva morphometrics, abnormalities, or cardiac activity. There was a treatment‐dependent up‐regulation of stress marker genes (hspa8, cyp1c1) but no indication of metal‐induced activation of metallothionien (mt gene transcription). Transcription markers for DNA and histone methyltransferases did show treatment‐related up‐regulation, indicative of altered methylation in larvae when developmental methylation patterns are determined, indicating some level of chronic toxicity that may have longer‐term effects. Environ Toxicol Chem 2019;38:1446–1454. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
Highlights
Mine tailings constitute the major waste product from extractive mineral industries and are made up of a fine‐grained slurry of milled rock, process chemicals, and elevated concentrations of metals from residual ore minerals (Kvassnes and Iversen 2013)
Because most of the particles were at the lower limit of size detection, small particles
The particle concentrations in the present study represent accepted mine tailings concentrations in the pelagic zone of the defined area influenced by the tailings deposition
Summary
Mine tailings constitute the major waste product from extractive mineral industries and are made up of a fine‐grained slurry of milled rock, process chemicals, and elevated concentrations of metals from residual ore minerals (Kvassnes and Iversen 2013). In Norway, there are presently 7 active sites where mine tailings are disposed of through submarine pipes into fjords, and tailings can remain suspended for prolonged periods in the water column because of slow settling rates of small particles and can be traced (up to 10 km) by increased water turbidity over considerable distances from the deposit outlet (Berge et al 2011; Ramirez‐Llodra et al 2015). Atlantic cod (Gadus morhua) from both coastal and northeast Arctic populations spawn in Norwegian fjords and are a major concern because the mine tailings may interact with and affect the early life stages (embryos and larvae) that coexist in and around tailings deposit sites. Atlantic cod spawn pelagic eggs in the range of 40–200 m depth in the period of March to May, and embryos, larvae, and juveniles persist in fjords for months or years depending on original stock and local water currents, with the potential for prolonged exposure to fine Mine tailings from metal ore extraction can have additional metal and process chemical toxicity effects (Swedmark and Granmo 1981; Olsvik et al 2015b), making evaluation of mine tailings effects a complex multistressor toxicological issue
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