Abstract: The present study was aimed to investigate the distribution characteristics and speciation of cadmium and arsenic in the edible tissues of Oratosquilla oratoria. The contents of total arsenic and cadmium and their species in the edible muscle and gonad were measured by using inductively coupled plasma mass spectrometry (ICP-MS). The free inorganic Cd2+ and different species of arsenic were analyzed with the high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The results showed that O. oratoria could accumulate high concentrations of cadmium in the edible tissues, and the concentration of total cadmium in all samples collected in the present study exceeded the maximum permissible concentration (MPC) of 0.50 mg/kg wet mass in China. In addition, the concentration of total cadmium was not significantly related to gender. The concentration of total cadmium in the gonad was almost 10 times as high as that in the muscle. Speciation analysis showed that the percentage of the most toxic free inorganic Cd2+ in relative to the total cadmium was below 20% for most of the samples, and there was a significantly positive relationship between the inorganic Cd2+ concentration and the total cadmium concentration. The total arsenic concentration in the edible tissues of O. oratoria was high regardless of gender. However, the concentration of total arsenic in the gonad was higher than that in the muscle. Inorganic arsenic was detected in all samples, and monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) were also found in some of the samples. The highest concentration of inorganic arsenic of 0.46 mg/kg was found in the muscle, which was below the maximum standard limit in our country, and the percentage of inorganic arsenic in relative to total arsenic in the muscle ranged from 1.71% to 6.14%. In addition, there was no significant relationship between inorganic arsenic and total arsenic for both the edible tissues examined. The organic arsenic AsB was the main species present in both the muscle and gonad of O. oratoria. Because of the high accumulation capacity for total cadmium and arsenic, it is urgent to establish a more accurate MPC of Cd for the edible tissues of O. oratoria. The metal bio-accessibility and bioavailability must be considered in order to improve the risk assessment analysis.

Key words: Oratosquilla oratoria, cadmium, arsenic, speciation analysis, distribution characteristics