3:00 PM - 3:15 PM
[MIS26-18] Elimination of the heavy metals from coastal water by scallop cultivation
Keywords:essential trace element, stable isotope, Japanese whiting, Japanese scallop, element elimination
The Japanese whiting Sillago japonica were collected from the coastal areas (Mutsu Bay: 7 sites, the Sea of Japan: 10 sites) of Aomori Prefecture, northern Japan, in 2012 and 2013. We determined the nitrogen and carbon stable isotope ratios of their muscles by DELTA-plus Isotope Ratio Mass Spectrometer coupled with NC2500 Elemental Analyzer (Thermo Fisher Scientific), the levels of 25 elements (Li, Mg, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Rb, Sr, Mo, Cd, In, Sn, Sb, Cs, Ba, Tl, Pb, Bi) in their livers by ICP-MS (Agilent, 7500cx), and the mercury levels in their livers by the cold vapor technique with an automatic mercury analyzer (Nippon Instruments Corporation, RA-3220A).
The carbon stable isotope ratios (δ13C) of Mutsu Bay specimens were higher than those of the Sea of Japan specimens. The nitrogen stable isotope ratios (δ15N) were not different in most of the sampling sites, but the ratios were obviously higher in the particular site of Mutsu Bay. It was considered that this phenomenon was locally caused by the unnatural nitrogen supply.
Moreover, the levels of 15 elements (Li ,Mg, Ca, Mn, Fe, Co, Cu, Zn, Rb, Sr, Mo, Cd, Cs, Hg, Pb) in the livers of Mutsu Bay specimens were significantly lower (p < 0.01, U test) than those in the Sea of Japan specimens. Especially, the levels of cadmium and mercury for δ15N values were obviously low in the Mutsu Bay specimens. This result suggested that some elements such as cadmium were brought out from Mutsu Bay by the landing of cultured scallops.
In Iwasaki fishing port (one of the sampling sites in the Sea of Japan), the levels of 8 elements (V, Fe, Co, Cu, Ga, Cd, Hg, Pb) of the specimens captured in 2012 were significantly higher (p < 0.01, U test) than those in 2013. In March 2012, a cargo ship was stranded nearby Iwasaki fishing port, and the oil spilled into the ocean.