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Trace metals and metallothioneins in rainbow trout (Oncorhynchus mykiss) exposed to various concentrations of acid rock drainage

University of British Columbia

An in situ experiment was conducted at the Equity Silver mine, near Houston, British Columbia in an attempt to induce hepatic metallothioneins and study metal uptake in rainbow trout (Oncorhynchus mykiss)using acid rock drainage (ARD). A mesocosm apparatus consisting of 16 flow-through troughs were placed over Foxy Creek, and fish were placed tubs at the end of selected troughs. Dilution rates of ARD:stream water were 0:1 (control), 1:25000, 1:10000, 1:2500, 1:1000, 1:250, and 1:25. Bioaccumulation of copper, zinc and cadmium was determined in the liver, gill and muscle tissue using atomic absorption spectroscopy. Hepatic metallothionein concentrations were measured using differential pulse polarography. Metal concentrations in the troughs were analyzed using inductively coupled argon emission spectroscopy. The water chemistry data was modelled using the geochemical model MINTEQA2 in an attempt to estimate metal bioavailability. It was concluded that pH and adsorbtion processes in the experimental troughs played a very important role in controlling the ARD toxicity. Hepatic metallothioneins were not elevated above background levels after23 days of exposure to various concentrations of ARD. Significant metal bioaccumulation occurred with zinc, and the source appeared to be the food which the experimental fish were fed. The 48 hour LC50 was calculated to occur when roughly 1 part ARD was mixed with 1400 parts stream water. At this mixing rate, the pH of the stream would have been reduced from 7 to roughly 6.8, and copper, zinc, aluminum and cadmium concentrations would have been 0.028, 0.027, 0.277 and 0.0003 mg•L-1respectively. The 23 day LC50 was calculated to occur when roughly 1 part ARD was mixed with 5150 parts stream water. At this dilution, the pH would have not been reduced below neutrality, and the copper, zinc, aluminum and cadmium concentrations would be 0.010, 0.014, 0.113 and 0.0001 mg•L-1 respectively.

Thesis/Dissertation

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2008-12-23

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http://hdl.handle.net/2429/3301

Biomedical Engineering

University of British Columbia

UBCV

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