Trace metal speciation and uptake in Atlantic salmon (Salmo salar) in coastal water

• Main Author: Nymo, Malene Therese
• Other Authors: Teien, Hans-Christian, Skipperud, Lindis, Jaroz, Emil
• Format: Master Thesis
• Language: English
• Published: Norwegian University of Life Sciences, Ås 2020
• Subjects: Uptake; Speciation; Trace metals; Cu; Zn; Al; Fish; Salmon; Coastal; Brackish; Norway; Atlantic salmon; Salmo salar
• Online Access: https://hdl.handle.net/11250/2724830

Estuarine environments have a high risk of metal pollution due to the influx from rivers. Freshwater from rivers mixed with seawater in coastal areas gives varied and complex water chemistry. In the estuarine environment of Kaldvellfjorden in Norway were the metals copper (Cu), zinc (Zn) and aluminum (Al) classified to have a high risk of impact. If these metals are bioavailable, based on their speciation, fish can accumulate the metals in tissue. To improve the knowledge of bioavailability and toxicity of metals in coastal waters are the main objectives of this thesis to identify the uptake of trace metals in fish in coastal water. Atlantic salmon smolts (Salmo salar) were exposed to waterborne Cu, Zn, or Al in brackish water (20‰, pH 8) for 96-hours. The exposures were conducted with nine concentrations of Cu and Zn, and six concentrations of Al. Several of the concentrations were the same, to directly compare the uptake between the metals. To investigate the uptake in fish; gills, kidneys, and livers were sampled at the end of the exposure. Metal concentrations were quantified using Inductively Coupled Plasma Mass spectrometry (ICP-MS). Water samples of the exposure water were size- and charge- fractionated in-situ at 0h and 96h, and analyzed later using ICP-MS. The results of size fractionation revealed that speciation of the Cu, Zn, and Al was relatively similar in brackish water, and was assumed to be bioavailable. Aluminum was found associated with the low molecular mass (LMM, <10kDa) fraction at >83% of the total, LMM-associated Zn at >78% of the total, while Cu had large uncertainties in this fraction. Copper was either associated with the colloidal or LMM fraction. Only a small percentage, <14%, of the metals were associated with particles. This low association is likely due to low organic content in the exposure water. The uptake of metals on fish followed the order, Al>Cu>Zn, where gills were the tissue with the highest uptake, kidneys intermediate and the liver had no uptake within ...