Monitoring and Human Health Assessment of Trace Elements in Fresh and Dry Fish From Lake Kariba, Siavonga, Zambia

Abstract

This study investigated the levels of trace elements in two fish species, Kariba bream (Oreochromis mortimeri) and Kapenta (Limnothrissa miodon) from Lake Kariba in two consecutive years, 2021 and 2022. Both Kariba Bream fresh/sun-dried muscle and sun-dried Kapenta tissues were digested using a microwave digestion system and analyzed using Inductively Coupled Plasma Mass Spectrometry. Mean concentration of trace elements between the first and second sampling differed significantly (P > 0.05). In the first sampling, concentrations of trace elements in sun-dried bream occurred in the order Fe > Al > Cr > Zn > Mn > As while Se, Cu, Cd, Pb and Hg were not detected. Sun-dried Kapenta displayed Al > Fe > Zn > Mn > Cr > Cu > As > Se with Cd, Pb and Hg not detected. Fresh bream showed Fe > Al > Zn > Cr > Mn > Cu > Se, with Pb, As, Cd and Hg not detected. In the second sampling, the order was, Fe > Al > Zn > Cr > Mn > Se > Cu > As in sun-dried bream; Fe > Zn > Mn > Al > Cr > Cu > Se > As in sun-dried Kapenta with Cd, Pb and Hg not detected in both. Fresh bream showed; Fe > Al > Zn > Mn > Cr > Se > Cu > As > Pb with Cd and Hg not detected. Notably, the concentrations of Fe, Mn and Cr in some samples exceeded the recommended limits by FAO/WHO. The THQ and HI for some elements were above the threshold value of 1, indicating potential risk of non-carcinogenic to human health for long-term consumption. These findings highlight the need for further investigation into post-fish handling, including land-use activities in and around the lake.