全新世早期遺址貽貝殼體穩定同位素紀錄所反映之馬祖亮島地區古環境
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2024
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本研究分析了馬祖亮島11件島尾遺址 Ⅰ （距今約8300 ~ 7400年前）與12件島尾遺址 Ⅱ （距今約7600 ~ 7400年前）遺址貽貝殼體的碳氧同位素成分，馬祖南竿地區的17個不同月份現生貽貝樣本和97個馬祖南竿與北竿地區海水樣品的穩定同位素成分，以重建馬祖地區全新世早期的古環境。 南竿地區水樣品的平均氫、氧同位素數值分別為-2.9 ± 2.6 ‰和-0.8 ± 0.4 ‰（平均值 ± 1σ；N = 49；V-SMOW）；北竿地區水樣品的平均氫、氧同位素數值分別為-2.7 ± 2.5 ‰和-0.8 ± 0.4 ‰（N = 48）。根據觀察到的同位素數值和鹽度紀錄，南竿、北竿水體的氧同位素值呈現季節性波動，並與淡水與海水混合的比例變化有關。 現生貽貝殼體的平均碳同位素數值，分別為-0.5 ± 0.4 ‰（N = 473；未水煮過）和-2.1 ± 0.6 ‰（N=31；水煮過）；平均氧同位素數值，分別為-1.9 ± 0.5 ‰（V-PDB；未水煮過）和-2.0 ± 0.7 ‰（水煮過）。受到沸水烹煮過後現生貽貝殼體的碳同位素數值比未煮沸貽貝殼體的碳同位素數值低，但沸水烹煮對現生貽貝殼體的氧同位素成分無顯著的影響。而現生貽貝左殼平均碳同位素數值為-0.4 ± 0.4 ‰（N=29），平均氧同位素數值平均值為-1.8 ± 0.4 ‰；現生貽貝右殼平均碳同位素數值為-0.5 ± 0. 3‰（N=29），平均氧同位素數值為-1.7 ± 0.5 ‰，貽貝左、右兩瓣殼體在碳、氧同位素組成上無顯著的差異。 馬祖亮島島尾遺址 Ⅰ 貽貝殼體的平均碳、氧同位素數值，分別為0.5 ± 0.5 ‰和-1.2 ± 0.6 ‰（N = 531）；島尾遺址 Ⅱ 遺址貽貝殼體的平均碳、氧同位素數值分別為0.7 ± 0.4 ‰和-1.6 ± 0.6 ‰（N = 394）。馬祖亮島島尾遺址 Ⅰ 與 Ⅱ 之遺址貽貝殼體的平均氧同位素數值有0.4 ‰的差異，扣除掉冰川效應所造成水體氧同位素0.2 ‰的影響，反映亮島於約8300 ~ 7400年前之間與約7600 ~ 7400年前之間的海水溫度可能低約1 ~ 2℃及/或當時的淡水混合量較少。 亮島島尾遺址貽貝殼體的平均碳同位素數值，比現生未煮沸貽貝殼體的平均碳同位素數值大約1%，反映出8300 ~ 7400年前馬祖地區水體的基礎生產力較高。馬祖亮島島尾遺址 Ⅰ 貽貝殼體的平均氧同位素數值，比現生貽貝殼體的平均氧同位素數值大約0.7 ‰，扣除掉冰川效應的影響，顯示當時的海水溫度可能比現在低約2 ~ 3℃及/或當時的淡水混合量較少；馬祖亮島島尾遺址 Ⅱ 貽貝殼體的平均氧同位素數值，比現生貽貝殼體的平均氧同位素數值大約0.3 ‰，扣除掉冰川效應的影響，顯示當時的海水溫度可能比現在低約0 ~ 1℃及/或當時的淡水混合量較少。現生和遺址標本單一殼體都可觀察到氧同位素數值的季節性波動，根據亮島島尾遺址 Ⅰ 最完整的6個與遺址 Ⅱ 最完整的7個貽貝標本，亮島島尾遺址 Ⅰ 採收季節分別為春夏（N = 3）、夏秋（N = 1）和冬季（N = 2）；亮島島尾遺址 Ⅱ 採收季節分別為春夏（N = 3）、夏秋（N = 2）和冬季（N = 2），採收季節分布大致平均。
This study analyzed archaeological Mytilus shells collected from the Daowei Site I (N = 11, ~ 8300 to 7400 year B.P.) and the Daowei Site II (N = 12, ~ 7600 to 7400 year B.P.) on the Liang Island, Matsu, to characterize the modern environment information. Additionally, 17 modern Mytilus samples collected from different months in the Nangan area of Matsu and 97 seawater samples collected from the Nangan and Beigan areas were analyzed for stable isotope composition. The average hydrogen and oxygen isotope values of the water samples from the Nangan area were -2.9 ± 2.6 ‰ and -0.8 ± 0.4 ‰ (mean ± 1σ; N = 49; V-SMOW), respectively. In the Beigan area, the average hydrogen and oxygen isotope values were -2.7 ± 2.5 ‰ and -0.8 ± 0.4 ‰ (N = 48), respectively. Based on the observed isotope values and salinity records, the oxygen isotope values in the water bodies of Nangan and Beigan exhibited seasonal fluctuations, related to the different mixing amount of freshwater and seawater. The average carbon isotope values of the modern Mytilus shells were -0.5 ± 0.4 ‰ (N = 473; unboiled) and -2.1 ± 0.6 ‰ (N = 31; boiled), respectively. The average oxygen isotope values were -1.9 ± 0.5 ‰ (V-PDB; unboiled) and -2.0 ± 0.7 ‰ (boiled). Carbon isotope values of the boiled modern Mytilus shells is less than those of unboiled. However, there is no significant difference in oxygen isotope values between unboiled and boiled modern Mytilus shells. The average carbon isotope and oxygen isotope values of the left values were -0.4 ± 0.4 ‰ (N = 29) and -1.8 ± 0.4 ‰, respectively. The average carbon isotope and oxygen isotope values of the right values were -0.5 ± 0.3 ‰ (N = 29) and -1.7 ± 0.5 ‰, respectively. There is no significant difference in carbon and oxygen isotope values between the left and right valves of Mytilus shells. The average carbon and oxygen isotope values of the archaeological Mytilus shells from the Daowei Site I on Liang Island, Matsu, were 0.5 ± 0.5 ‰ and -1.2 ± 0.6 ‰ (N = 531), respectively; the average carbon and oxygen isotope values of the Mytilus shells from the Daowei Site II were 0.7 ± 0.4 ‰ and -1.6 ± 0.6 ‰ (N = 394), respectively. The difference in the average oxygen isotope values between the Mytilus shells from Sites I and II was 0.4 ‰. After accounting for a 0.2 ‰ effect due to the ice volume effect, this indicates that the seawater temperature in ~ 8300 to 7400 year B.P. could have been 1 to 2°C lower and/or there was less freshwater mixing than that in ~ 7600 to 7400 year B.P. in Liang Island area. The average carbon isotope values of the Mytilus shells from the Daowei Site I and II were 1‰ greater than that of modern, which may reflect higher primary productivity between 8300 and 7400 years ago B.P. The average oxygen isotope values of the Mytilus shells from Daowei Site I were about 0.7 ‰ greater than that of modern. After accounting for the ice volume effect (0.2 ‰), this suggests that the seawater temperature at that time was likely 2 to 3°C lower and/or there was less freshwater mixing than present. The average oxygen isotope values of the Mytilus shells from Daowei Site II were about 0.3 ‰ greater than that of modern Mytilus shells. After accounting for the ice volume effect, this suggests that the seawater temperature at that time was likely 0 to 1°C lower and/or there was less freshwater mixing than present. Seasonal fluctuations in oxygen isotope values were observed in both modern and archaeological specimens. Based on the six most complete archaeological mussel specimens from Daowei Site I and the seven most complete specimens from Daowei Site II, the harvest seasons for Daowei Site I were spring-summer (N = 3), summer-autumn (N = 1), and winter (N = 2); the harvest seasons for Daowei Site II were spring-summer (N = 3), summer-autumn (N = 2), and winter (N = 2). In general, the harvest seasons for Daowei Site I and II were evenly distributed.
This study analyzed archaeological Mytilus shells collected from the Daowei Site I (N = 11, ~ 8300 to 7400 year B.P.) and the Daowei Site II (N = 12, ~ 7600 to 7400 year B.P.) on the Liang Island, Matsu, to characterize the modern environment information. Additionally, 17 modern Mytilus samples collected from different months in the Nangan area of Matsu and 97 seawater samples collected from the Nangan and Beigan areas were analyzed for stable isotope composition. The average hydrogen and oxygen isotope values of the water samples from the Nangan area were -2.9 ± 2.6 ‰ and -0.8 ± 0.4 ‰ (mean ± 1σ; N = 49; V-SMOW), respectively. In the Beigan area, the average hydrogen and oxygen isotope values were -2.7 ± 2.5 ‰ and -0.8 ± 0.4 ‰ (N = 48), respectively. Based on the observed isotope values and salinity records, the oxygen isotope values in the water bodies of Nangan and Beigan exhibited seasonal fluctuations, related to the different mixing amount of freshwater and seawater. The average carbon isotope values of the modern Mytilus shells were -0.5 ± 0.4 ‰ (N = 473; unboiled) and -2.1 ± 0.6 ‰ (N = 31; boiled), respectively. The average oxygen isotope values were -1.9 ± 0.5 ‰ (V-PDB; unboiled) and -2.0 ± 0.7 ‰ (boiled). Carbon isotope values of the boiled modern Mytilus shells is less than those of unboiled. However, there is no significant difference in oxygen isotope values between unboiled and boiled modern Mytilus shells. The average carbon isotope and oxygen isotope values of the left values were -0.4 ± 0.4 ‰ (N = 29) and -1.8 ± 0.4 ‰, respectively. The average carbon isotope and oxygen isotope values of the right values were -0.5 ± 0.3 ‰ (N = 29) and -1.7 ± 0.5 ‰, respectively. There is no significant difference in carbon and oxygen isotope values between the left and right valves of Mytilus shells. The average carbon and oxygen isotope values of the archaeological Mytilus shells from the Daowei Site I on Liang Island, Matsu, were 0.5 ± 0.5 ‰ and -1.2 ± 0.6 ‰ (N = 531), respectively; the average carbon and oxygen isotope values of the Mytilus shells from the Daowei Site II were 0.7 ± 0.4 ‰ and -1.6 ± 0.6 ‰ (N = 394), respectively. The difference in the average oxygen isotope values between the Mytilus shells from Sites I and II was 0.4 ‰. After accounting for a 0.2 ‰ effect due to the ice volume effect, this indicates that the seawater temperature in ~ 8300 to 7400 year B.P. could have been 1 to 2°C lower and/or there was less freshwater mixing than that in ~ 7600 to 7400 year B.P. in Liang Island area. The average carbon isotope values of the Mytilus shells from the Daowei Site I and II were 1‰ greater than that of modern, which may reflect higher primary productivity between 8300 and 7400 years ago B.P. The average oxygen isotope values of the Mytilus shells from Daowei Site I were about 0.7 ‰ greater than that of modern. After accounting for the ice volume effect (0.2 ‰), this suggests that the seawater temperature at that time was likely 2 to 3°C lower and/or there was less freshwater mixing than present. The average oxygen isotope values of the Mytilus shells from Daowei Site II were about 0.3 ‰ greater than that of modern Mytilus shells. After accounting for the ice volume effect, this suggests that the seawater temperature at that time was likely 0 to 1°C lower and/or there was less freshwater mixing than present. Seasonal fluctuations in oxygen isotope values were observed in both modern and archaeological specimens. Based on the six most complete archaeological mussel specimens from Daowei Site I and the seven most complete specimens from Daowei Site II, the harvest seasons for Daowei Site I were spring-summer (N = 3), summer-autumn (N = 1), and winter (N = 2); the harvest seasons for Daowei Site II were spring-summer (N = 3), summer-autumn (N = 2), and winter (N = 2). In general, the harvest seasons for Daowei Site I and II were evenly distributed.
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Keywords
紫殼菜蛤, 穩定同位素, 馬祖亮島島尾遺址, 古環境, Mytilus edulis, stable isotope, Matsu Liangdao-Daowei archaeological site, paleoenvironment