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绰墩农业遗址第六次发掘中发现大量的古碳化稻粒,经14C定年分析证明该碳化稻粒属于马家浜文化时期(7~6kaBP)的产物.为探求古碳化稻粒的形成机制,比较了古碳化稻粒与现代稻粒FT-IR光谱和热重分析的差异;并通过实验室方法在氦气氛围下制成现代碳化稻粒,利用CP/MAS-13C-NMR光谱对古碳化稻粒与现代碳化稻粒的碳进行结构表征.结果表明:与现代稻粒相比,古碳化稻粒中存在大量的芳香族成分;随着氧化时间和温度的增加,现代碳化稻粒中的脂肪族成分不断减少,同时伴随芳香族成分的累积;氧化的时间越长、温度越高,现代碳化稻粒的结构组成越接近古碳化稻粒.同时,现代碳化稻粒的FT-IR光谱和热重分析结果也表明,通过人为氧化可使现代稻粒达到与古碳化稻了相似的结构组成.从而说明与火相关的原始耕作方式可能是古碳化稻粒的来源.
A large number of ancient carbonized rice grains were found in the sixth excavation of Chuodun agricultural site and the results of 14C dating proved that the carbonized rice grains belong to the product of Majiabang culture period (7 ~ 6kaBP) .In order to explore the formation mechanism of ancient carbonized grain, The differences between FT-IR spectra and TG-TG spectra of pale-carbonized rice grains and modern rice grains were compared. The modern carbonized rice grains were prepared by laboratory method in helium atmosphere. The carbonation of pale-carbonized grains by CP / MAS-13C-NMR spectroscopy The results showed that there were a large number of aromatic components in ancient carbonized rice grains compared with modern rice grains. With the increase of the oxidation time and temperature, the contents of carbon in modern carbonized rice grains The composition of modern carbonized rice grains is closer to that of ancient carbonized rice grains with the longer oxidation time and the higher temperature.The FT-IR spectra of modernized carbonized rice grains and The results of TGA also showed that modern rice grains can reach the similar structure with that of the ancient carbonized rice by means of anthropogenic oxidation, indicating that the original fire-related farming methods may be the source of the ancient carbonized rice grains.