Accumulation Characteristics of Trace Elements in Fish from High-Altitude Lakes and Risk Assessment: A Case Study of Nam Co Lake

Abstract

This study investigated the Bioaccumulation of 14 trace elements (Li, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Cd, Ba, Pb, Bi) in six tissues types (muscle, gill, liver, intestine, heart and gallbladder) of five wild fish species (Schizothorax waltoni, Schizothorax o’connori, Schizothorax macropogon, Schizopygopsis younghusbandi, and Oxygymnocypris stewartii) inhabiting Nam Co Lake, Tibet. Elemental concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that Zn and Cu were the most enriched elements across all tissues. Significant differences in trace element concentrations were observed among different fish species and tissues (p < 0.05), with the omnivorous species S. macropogon exhibiting the highest trace element concentrations. Among the examined tissues, gills and liver were identified as the primary accumulation sites, while muscle exhibited the lowest concentrations. Correlation analysis and Hierarchical Cluster Analysis (HCA) revealed that fish body size had no significant impact on the accumulation of most trace elements. However, strong correlations were observed between Ti, Sr, and Ba, as well as between Cu, Zn, and Cd, suggesting common environmental or physiological factors influencing their accumulation. Based on the risk assessment results, it was demonstrated that the fish were not affected by significant trace element contamination, and that the consumption of these fish would not pose a health risk (Metal Pollution Index (MPI) < 2, the Hazard Quotient (THQ) < 1). These findings provide a scientific basis for future studies on long-term trace element accumulation trends and contribute to the ecological protection and management of alpine lake ecosystems.