Bioaccumulation of zinc and lead in carp and its traceability in the food chain

This study was conducted in the Fish Nutrition Laboratory of the Animal Production Department, College of Agriculture and Forestry, University of Mosul, to study the bioaccumulation of zinc and lead in the environment, food, and bodies of carp. To implement this study, three experiments were conducted to grow, produce, and feed Hydrilla plants, determine zinc and lead concentrations, and track them in the food chain. In the first experiment, Hydrilla plants were grown in three sources of organic and compound fertilizers, and the productivity of Hydrilla plants and the levels of heavy elements (zinc and lead) were estimated. In the second experiment, Hydrilla plants were grown in two culture levels, and their productivity and heavy element levels were estimated. The results of this experiment were taken from Hydrilla plants and used in the third experiment to feed carp. The results showed an increase in zinc concentrations with the progression of the plant's growth period in the medium. However, lead concentrations were unaffected throughout all periods (from zero to 15 days) of growth. Conversely, higher lead concentrations were found in carp diets containing 15 and 20% hydrilla compared to the control treatment, while zinc concentrations did not differ between the treatments. Zinc and lead concentrations in carp differed from their concentrations in the diets. Zinc concentrations increased in fish fed diets containing 15 and 20% hydrilla, while lead levels in the fish remained unaffected despite the different hydrilla content in the diets.