Spatial and interspecies differences in concentrations of eight trace elements in wild freshwater fishes at different trophic levels from middle and eastern China.

There have been numerous studies on concentrations of trace elements in aquatic ecosystems, but few have been conducted at a large spatial scale. This study collected 410 samples of five wild freshwater fishes at different trophic levels from middle and eastern China. Concentrations of eight trace elements, chromium (Cr), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), lead (Pb) and cadmium (Cd) and stable isotope ratios (δ13C and δ15N) were determined in dorsal muscle of fishes. Spatially, concentrations of trace elements were least in fishes from the Hai River Basin, while those in fishes from the Taihu Lake Basin were greatest. The carnivorous topmouth culter and omnivorous common carp and crucian carp accumulated greater amounts of trace elements than did the planktivorous silver carp and bighead carp. Trophic biomagnification was for Cu, Fe and Zn, but not for Cr, Ni, As, Pb and Cd. Concentrations of As in 15 muscle samples (3.7%) from Taihu Lake Basin exceeded the guidelines (1.0 mg/kg, wet mass) provided by FAO/WHO (2014), while the total target hazard quotient (TTHQ) values were <1.0, indicating no obvious non-carcinogenic risks to humans that consume those fishes. However, people who consume larger amounts of fish products, or people who are vulnerable, such as pregnant women, children and people with poor health, might be at greater risk. Also, exposure to trace metals through other routes cannot be ignored. Accumulations of trace elements in Chinese freshwater fishes were affected by both geographical conditions and human activities.