Uranium transfer and accumulation in organs of Danio rerio after waterborne exposure alone or combined with diet-borne exposure
Résumé
Uranium (U) toxicity patterns for fish have been mainly determined under laboratory‐controlled waterborne exposure conditions. Because fish can take up metals from water and diet under in situ exposure conditions, a waterborne U exposure experiment (20 μg L−1, 20 d) was conducted in the laboratory to investigate transfer efficiency and target organ distribution in zebrafish Danio rerio compared with combined waterborne exposure (20 μg L−1) and diet‐borne exposure (10.7 μg g−1). 233Uranium was used as a specific U isotope tracer for diet‐borne exposure. Bioaccumulation was examined in the gills, liver, kidneys, intestine, and gonads of D. rerio. Concentrations in the organs after waterborne exposure were approximately 500 ng g−1 fresh weight, except in the intestine (> 10 μg g−1 fresh wt) and the kidneys (200 ng g−1 fresh wt). No significant difference was observed between waterborne and diet‐borne conditions. Trophic U transfer in organs was found but at a low level (< 10 ng g−1 fresh wt). Surprisingly, the intestine appeared to be the main target organ after both tested exposure modalities. The gonads (57% at 20 d) and the liver (41% at 20 d) showed the highest accumulated relative U burdens.