Bakhshalizadeh et al. 2023 — REEs and trace elements in golden grey mullet, Caspian Sea
This primary study determined concentrations of rare earth elements (REEs) and four trace elements (As, Cd, Hg, Pb) by ICP-MS in five tissues (muscle, intestine, kidney, liver, gill) of twenty golden grey mullet (Chelon auratus) caught from the southern Caspian Sea. Cadmium and lead concentrations in muscle tissue were reported to be of concern for human health, and terbium concentrations were anomalously high suggesting anthropogenic contamination, probably associated with oil extraction activity in the Caspian region.
Key numbers
All values are medians in ng/g wet weight (Table 2):
Muscle tissue (the food-relevant compartment):
- As: 497 ng/g (median), IQR 367 ng/g
- Cd: 23.8 ng/g (median), IQR 40.7 ng/g
- Hg: 29.6 ng/g (median), IQR 15.9 ng/g
- Pb: 67.2 ng/g (median), IQR 114 ng/g
Liver tissue (highest accumulation organ for As, Cd, Hg):
- As: 2389 ng/g (median)
- Cd: 1689 ng/g (median)
- Hg: 212 ng/g (median)
- Pb: 122 ng/g (median)
Authors state Cd and Pb levels in muscle were “of concern” relative to human consumption benchmarks.
REEs (reported as pg/g): Y was the most abundant REE (median 1460 pg/g across tissues), and Tb anomalously elevated relative to earth crust abundance ratios, attributed to anthropogenic Caspian pollution. REE concentrations in muscle were the lowest of any tissue.
n=20 fish; ICP-MS (Agilent 8900); certified reference material DORM-4 used for QA; recovery 97-104%.
Methods (brief)
ICP-MS (Agilent 8900) analysis of five tissues per fish. Acid digestion with HNO3/H2O2. CRM DORM-4 (fish protein, NRC Canada) for trace elements; CRM REE-1 for rare earths. LOD and LOQ calculated from 10 independent blank measurements. Nonparametric Kruskal-Wallis test with Bonferroni correction for inter-tissue comparisons. All values wet weight.
Implications
Certification: Muscle Cd (23.8 ng/g) and Pb (67.2 ng/g) in Caspian mullet are at levels of regulatory concern; contributes to geographic risk context for Caspian Sea and Iranian fish sources. Courses: Illustrates tissue distribution hierarchy for trace metals in fish (intestine > kidney/gill > liver > muscle for REEs; liver >> other tissues for Cd, As, Hg) alongside emerging REE contamination data. App: Supports per-species, per-region risk differentiation for marine/brackish fish from industrially impacted water bodies.