Bioaccumulation of copper nanoparticle in gill, liver, intestine and muscle of Siberian sturgeon (Acipenser baerii) juvenile

Copper (Cu) is an essential element required by all living organisms, since at least 30 enzymes are known to use Cu as a cofactor. Cu is also toxic in excess and liver and gills are known to be target organs for it. In the present study, 240 Siberian sturgeon juvenile (with initial weight 29.2 ± 3.1 g and initial length 21.8 ± 1.4 cm) were randomly distributed in 12 fiberglass tanks at 4 different copper nanoparticle (Cu-NPs) treatments with 3 replicates. Treatments included control (T0 = no added Cu-NPs), 50 (T50), 100 (T100), 200 (T200) µg.l-1 Cu-NPs (mean primary particle size of 2 - 6 nm) in a semi-static waterborne exposure regime. Water exchanged were 20% daily with re-dosing after each change. The experimental period lasted 28 days, 14 days exposure to Cu-NPs and 14 days as recovery time. Fish liver, gill, intestine and muscle were sampled at days 0, 7, 14, 21 and 28. Samples were weighed, dried (100 ◦C for 48 h) then digested in concentrated nitric acid in a water bath, cooled, and analyzed for Cu concentration in the tissues with graphite furnace atomic absorption spectroscope. Most of the Cu-NPs were accumulated in the intestine, gill, liver and muscle. The accumulation of NPs in tissues was increased in all treatments from day 7 through 14. In the recovery period, Cu-NPs in tissues decreased but it was still higher than the control treatment. The current findings indicate that preventing the entry of Cu-NPs into the aquatic environment would seem to be essential.