[Enrichment of Cd2+ and Hg2+ in Phascolosoma esculenta and their effects]

The accumulation of Cd2+ and Hg2+ in Phascolosoma esculenta and its effects on its growth and main nutrient components were investigated using atomic absorption spectrometer analysis and atomic fluorescence spectrometer examination. The results showed that within the experimental heavy metal concentrations, the amounts of Cd2+ and Hg2+ accumulated in the somatic muscles increased with increasing exposure time and reached their saturated levels at the end of the experiment. Exposure of higher heavy metal concentrations speeded up the accumulation of Cd2+ and Hg2+ and subsequently took less time to reach their saturated levels, which were greater than those of lower concentration groups. The rate of mass gain of P. esculenta decreased with increasing the heavy metal exposure concentrations. The combination exposure of Cd2+ and Hg2+ led to a significantly lower mass gain rate compared to those exposed to Cd2+ or Hg2+. The protein content of somatic muscles increased with the increase of exposure concentration and reached the maximum values at 0.05 and 0.02 mg · L(-1) for Cd2+ and Hg2+, respectively. After that, the protein content of somatic muscles began to decrease. The combined exposure of the two heavy metals showed similar effect trends but more significant impacts on the protein content of somatic muscles. The lipid content of somatic muscles decreased with increasing the concentration of Cd2+ or Hg2+ exposure, and the combination of Cd2+ and Hg2+ led to lower lipid content.