Bioaccumulation of metals in black mussels (Mytilus galloprovincialis) in Cape Town Harbour, South Africa

Heavy metal concentrations in black mussels (Mytilus galloprovincialis) collected from Cape Town Harbour were determined using energy dispersive X-ray fluorescence (EDXRF) and inductively coupled plasma-mass spectrometry (ICP-MS). EDXRF showed that tissue portions of the mussels contained K, Ca, Fe, Cu, Zn, Si, Sr, Al and Au, while the shell portion contained K, Ca, Fe, Cr, Zn, Si and Sr. In addition to these metals, EDXRF also revealed the presence of Al in the shells of the largest mussels. Highest concentrations of Cu and Zn were recorded in the tissues of the smallest mussels. Due to poorer detection limits of EDXRF, ultra-trace elements (Mn, Pb, As, Hg, V, Cr, Sn, Cd, Ni and Co) were determined in mussels using ICP-MS. The average metal concentrations found in the mussels are as follows; Pb (7.30 ± 0.67), Cd (1.98 ± 0.13), Hg (4.92 ± 0.60), As (6.94 ± 0.04), Sn (2.63 ± 0.13), Ni (1.88 ± 0.05), Cr (3.54 ± 0.05), V (4.17 ± 0.23), Co (0.74 ± 0.01) and Mn (35.20 ± 1.46). ANOVAs, Pearson correlation and principal component analysis (PCA) were employed in data analysis. The order of the abundance of metals in the mussels is Mn > Pb > As > Hg > V > Cr > Sn > Cd > Ni > Co. The average metal concentrations found in the mussels were higher than the permissible Food and Agriculture Organization (FAO) limits and other international guidelines.