5:15 PM - 6:45 PM
[HTT16-P13] Research about the origin of shells excavated from archaeological sites by carbon and nitrogen isotope analysis: Comparative study of isotope ratios in three sea areas
Keywords:shellfish, identification of locality, carbon isotope ratio, nitrogen isotope ratio
Shellfish have been useful as a food resource since the Jomon period, and shells were processed into ornaments such as shell bracelet, and tools. Since the Middle Ages, a variety of shellfish have been transported to distant areas and used as food resources over a wide range of areas. Because the shape of the shell does not reveal the place of origin, it is unclear in what waters the sea shell was collected and transported. If we can understand the origin of shellfish, we can reveal the actual conditions of people's movement, distribution areas, and import routes of goods in each area. Elucidating the origin of shellfish is an important archaeological research topic.
The presenters have been working on estimating the origin of marine fish using carbon(C) and nitrogen(N) isotope analysis. Even for the same fish species, the C and N isotope ratios of bone collagen differ in the Seto Inland Sea, the Sea of Japan, and the Pacific Ocean, and the isotope ratios revealed the origin of marine fish excavated from the Heiankyo site in Kyoto and the Yokkaichi site in the Saijo Basin.
Seashells are made of calcium carbonate and a protein called conchiolin, and it has been confirmed that conchiolin remains in fossils and shells excavated from the sites (Akiyama 1964). Compared to marine fish, the isotope ratio characteristics of each habitat area have been recorded for shellfish, which rarely move around in their habitat, and the C-N isotope ratio of shells will provide strong evidence to identify the place of origin.
In this presentation, we will report the results of conduct C-N isotope analysis of modern Japanese littleneck calms(Ruditapes philippinarum) collected in the Seto Inland Sea, Sea of Japan, and Pacific Ocean, and hard clams(Meretrix lusoria) excavated from three Jomon period sites located in coast of the Seto Inland Sea, Sea of Japan, and Pacific Ocean. Each sample was extracted for conchiolin according to Akiyama (1964) and Mae et al.(2007). Two pretreatment methods were used: 30% hydrogen peroxide and 0.1mol/L hydrochloric acid, wash for 5 minutes each to remove surface contamination, wash multiple times with ultrapure water to neutralize, and dry at 80℃ overnight. Next, it was ground in an agate mortar, 0.5 g to 2.0 g of the powder was placed in a cellulose tube, and conchiolin was extracted by reacting it with a 0.5 mol/L EDTA solution while keeping it warm at about 40℃. Then, the EDTA solution was replaced with ultrapure water, taken out from the cellulose tube into a 15 ml centrifuge tube, and lyophilized. 0.3mg to 0.6mg of extracted powdered conchiolin was weighed into a tin cup and measured using a stable isotope ratio mass spectrometer with an elemental analyzer (EA-IRMS).
In this presentation, we will report the measurement results and discuss the effectiveness and challenges of estimating the locality of marine shellfish based on C-N isotope ratios.
The presenters have been working on estimating the origin of marine fish using carbon(C) and nitrogen(N) isotope analysis. Even for the same fish species, the C and N isotope ratios of bone collagen differ in the Seto Inland Sea, the Sea of Japan, and the Pacific Ocean, and the isotope ratios revealed the origin of marine fish excavated from the Heiankyo site in Kyoto and the Yokkaichi site in the Saijo Basin.
Seashells are made of calcium carbonate and a protein called conchiolin, and it has been confirmed that conchiolin remains in fossils and shells excavated from the sites (Akiyama 1964). Compared to marine fish, the isotope ratio characteristics of each habitat area have been recorded for shellfish, which rarely move around in their habitat, and the C-N isotope ratio of shells will provide strong evidence to identify the place of origin.
In this presentation, we will report the results of conduct C-N isotope analysis of modern Japanese littleneck calms(Ruditapes philippinarum) collected in the Seto Inland Sea, Sea of Japan, and Pacific Ocean, and hard clams(Meretrix lusoria) excavated from three Jomon period sites located in coast of the Seto Inland Sea, Sea of Japan, and Pacific Ocean. Each sample was extracted for conchiolin according to Akiyama (1964) and Mae et al.(2007). Two pretreatment methods were used: 30% hydrogen peroxide and 0.1mol/L hydrochloric acid, wash for 5 minutes each to remove surface contamination, wash multiple times with ultrapure water to neutralize, and dry at 80℃ overnight. Next, it was ground in an agate mortar, 0.5 g to 2.0 g of the powder was placed in a cellulose tube, and conchiolin was extracted by reacting it with a 0.5 mol/L EDTA solution while keeping it warm at about 40℃. Then, the EDTA solution was replaced with ultrapure water, taken out from the cellulose tube into a 15 ml centrifuge tube, and lyophilized. 0.3mg to 0.6mg of extracted powdered conchiolin was weighed into a tin cup and measured using a stable isotope ratio mass spectrometer with an elemental analyzer (EA-IRMS).
In this presentation, we will report the measurement results and discuss the effectiveness and challenges of estimating the locality of marine shellfish based on C-N isotope ratios.