臺南科學園區考古遺址血蚶殼體穩定碳氧同位素組成所反映距今5000年前以來之古環境意義
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2024
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本研究藉由分析46枚於臺南科學園區所發掘的血蚶殼體的碳氧同位素記錄，重建過去約5000年以來臺灣西南部溫度及降雨強度的變化，並探討當時人類採集血蚶貝類的季節。 分屬7個時期的11個考古遺址血蚶殼體氧同位素分析結果為：（1）大坌坑文化（距今5000至4200年前）南關里東遺址血蚶平均δ13C數值為-3.65±1.61‰（N=182），平均δ18O數值為-2.91±1.34‰。（2）牛稠子文化（距今4200至3300年前）右先方遺址血蚶平均δ13C數值為-3.11±1.03‰（N=132），平均δ18O數值為-2.79±1.17‰。（3）大湖文化大湖期（距今3300至2800年前）瘦砂遺址血蚶平均δ13C數值為-2.85±1.06‰（N=145），平均δ18O數值為-2.97±1.49‰。（4）大湖文化烏山頭期（距今2800至2000年前）王甲南與旗竿地二遺址血蚶平均δ13C數值為-2.53±1.33‰（N=559），平均δ18O數值為-3.02±1.37‰。（5）蔦松文化蔦松期蔦松文化蔦松期（距今1400至1000年前）木柵西、旗竿地遺址血蚶平均δ13C數值為-1.77±1.44‰（N=471），平均δ18O數值為-3.19±1.34‰。（6）西拉雅文化（距今500至300年前）社內遺址血蚶平均δ13C數值為-2.91±1.10‰（N=636；劉冠辰，2012），平均δ18O數值為-3.45±1.52‰。（7）近代漢人文化（距今300年前至現今）木柵、堤塘、埤子頭、王甲遺址血蚶平均δ13C數值為-2.45±1.14‰（N=1465），平均δ18O數值為-2.91±1.66‰。 不同文化相的遺址血蚶碳同位素數值有較大的差異，這些差異較有可能與水體δ13CDIC之變化有關；大坌坑文化至牛稠子、大湖文化大湖期、大湖文化烏山頭期及蔦松文化蔦松期的δ18O數值均為-3‰左右，並無顯著差異；至西拉雅文化δ18O數值減小0.26‰，氣候可能變得較為暖/濕；至近代漢人文化δ18O數值大了0.54‰，氣候可能變得較為冷/乾；而近代漢人文化與現今則無顯著差異，數值均為-3‰左右。 遺址血蚶氧同位素記錄呈現季節性震盪，單一殼體最高及最低氧同位素數值可分別反映出臺灣西南部的冬季及夏季記錄。大坌坑文化至牛稠子文化、大湖文化大湖期及大湖文化烏山頭期的冬季δ18O數值無顯著差異；至蔦松文化蔦松期冬季δ18O數值減小0.27‰，冬季溫度可能變得較高；至西拉雅文化冬季δ18O數值無顯著變化；至近代漢人文化冬季δ18O數值大了0.71‰，冬季氣溫可能變得較低。根據霰石溫度轉換方程式計算，近代漢人文化冬季溫度較距今5000至300年前冬季溫度低了1.6至2°C，且較現今溫度低了2.3°C，顯示近代漢人遺址血蚶可能記錄到了小冰期（LIA，Little Ice Age；西元1250至1860年）的北半球降溫時期。此外，近代漢人文化及大湖文化大湖期較小的血蚶夏季δ18O數值顯示小冰期及距今3300至2800年前可能有較多的夏季降雨量，而降雨量之增加可能與颱風頻率增加相關。 血蚶氧同位素數值可能可以反映殼體的採集季節，大坌坑文化南關里東遺址血蚶採收季節主要為春季（67%；N=3）；牛稠子文化右先方遺址血蚶採收季節主要為春季（67%；N=3），其次為冬季（33%）；大湖文化大湖期瘦砂遺址血蚶採收季節主要為春季（100%；N=2）；大湖文化烏山頭期王甲南遺址血蚶採收季節主要為夏季（75%；N=4），其次為秋季（25%），旗竿地二遺址血蚶採收季節主要為冬季及春季（80%；N=5）；蔦松文化蔦松期木柵西遺址血蚶採收季節為秋季（100%；N=1），旗竿地遺址血蚶採收季節主要為春季（67%；N=6）；西拉雅文化社內遺址血蚶採收季節主要為秋季（40%；N=53），其次為夏季（32%）；近代漢人文化木柵遺址血蚶採收季節主要為春季（100%；N=3），堤塘遺址血蚶採收季節主要為夏季（80%；N=5），埤子頭遺址血蚶採收季節主要為冬季（80%；N=5），王甲遺址血蚶採收季節主要為春季（60%；N=5）。整體而言，距今5000年前以來遺址人類較常在春、夏季採集血蚶。
This study reconstructs the variations in rainfall intensity and temperature of southwestern Taiwan over the past 5000 yr BP by analyzing the stable carbon and oxygen isotope records of 46 Tegillarca granosa shells collected from archaeological sites in Tainan Science Park. It also explores the seasons in which humans collected T. granosa. The stable oxygen isotope values of archaeological T. granosa shells are as follows: the T. granosa collected from Dabenkeng culture(5000-4200 yr BP), NKLE site （Nanguanli East Site） have an average δ13C value of -3.65±1.61‰ (N=182) and an average δ18O value of -2.91±1.34‰; the Niuchouzi culture (4200-3300 yr BP), YHF site （Youxianfang Site） have an average δ13C value of -3.11±1.03‰ (N=132) and an average δ18O value of -2.79±1.17‰; the Dahu culture, Dahu Phase(3300-2800 yr BP), SOS （Shousha Site） site have an average δ13C value of -2.85±1.06‰(N=145) and an average δ18O value of -2.97±1.49‰; the Dahu culture, Wushantou Phase (2800-2000 yr BP), WCS site（Wangjia South Site）and CKT2 site（Qigandi 2 Site） have an average δ13C value of -2.53±1.33‰(N=559) and an average δ18O value of -3.02±1.37‰; the Niaosong culture, Niaosong Phase(1400-1000 yr BP), MCW（Muzha WestSite）and CKT（Qigandi Site）sites have an average δ13C value of -1.77±1.44‰(N=471) and an average δ18O value of -3.19±1.34‰; the Siraya culture(500-300 yr BP), SN（Shenei Site）site have an average δ13C value of -2.91±1.10‰ (N=636；劉冠辰，2012) and an average δ18O value of -3.45±1.52‰; Han Chinese culture (300 yr BP to present), MC（Muzha Site）, TT（Titang Site） , PTT（Pizitou Site） and WC（Wangjia Site） sites have an average δ13C value of -2.45±1.14‰ (N=1465) and an average δ18O value of -2.91±1.66‰. The stable carbon isotope values of T. granosa from different cultural phases show significant differences, which are likely related to changes in the δ13CDIC of the water. The δ18O average values from the Dabenkeng culture to the Niuchouzi culture, Dahu culture, Dahu Phase, Dahu culture, Wushantou Phase, and Niaosong culture, Niaosong Phase are all around -3‰, with no significant differences. In the Siraya culture, the δ18O values decreased by 0.26‰, suggesting that the climate may have become warmer/wetter. In the Han Chinese culture, the δ18O values increased by 0.54‰, indicating that the climate may have become colder/drier. There is no significant difference between the modern Han Chinese culture and the present, with values around -3‰. The winter δ18O values of T. granosa from the Dabenkeng culture to the Niuchouzi culture, Dahu culture, Dahu Phase, and Dahu culture, Wushantou Phase shows no significant differences. The Niaosong culture, Niaosong Phase shows a decrease of 0.27‰ in winter δ18O values, indicating potentially higher winter temperatures. The Siraya culture shows no significant change in winter δ18O values. The Han Chinese culture shows an increase of 0.71‰ in winter δ18O values, suggesting potentially lower winter temperatures. According to the aragonite oxygen isotope and temperature equation, the winter temperatures during the Han Chinese culture were 1.6-2°C lower than those from 5000 to 300 yr BP and were 2.3°C lower than present temperatures. This suggests that T. granosa collected from Han Chinese culture may have recorded the Little Ice Age, a cooling period of north hemisphere. Additionally, the summer lower δ18O values of T. granosa shells collected from Dahu culture, Dahu Phase and Han Chinese culture indicate that the Little Ice Age and the period from 3,300 to 2,800 yr BP may have experienced higher summer rainfall, which may be related to typhoons. The oxygen isotope values of T. granosa might reflect the season in which the shells were collected. At NKLE site of Dabenkeng Culture, T. granosa was primarily harvested in the spring (67%; N=3). At YHF site of Niuchouzi Culture, T. granosa was mainly harvested in the spring (67%; N=3), followed by winter (33%). At SOS site of Dahu Culture, T. granosa was harvested mainly in the spring (100%; N=2). At WCS site of Dahu Culture,Wushantou phase, T. granosa was primarily harvested in the summer (75%; N=4), followed by autumn (25%). At the CKT2 site, T. granosa was harvested mainly in the winter and spring (80%; N=5). At MCW site of Niaosong Culture, Niaosong phase, T. granosa was harvested in the autumn (100%; N=1), and at CKT site, it was mainly harvested in the spring (67%; N=6). At SN site of Siraya Culture, T. granosa was primarily harvested in the autumn (40%; N=53), followed by summer (32%). At Han Chinese Culture, T. granosa was harvested mainly in the spring (100%; N=3) at MC site, in the summer (80%; N=5) at TT site, in the winter (80%; N=5) at the PTT site, and mainly in the spring (60%; N=5) at the WC site. Overall, humans were more commonly harvesting T. granosa in the spring and summer over the past 5000 B.P..
This study reconstructs the variations in rainfall intensity and temperature of southwestern Taiwan over the past 5000 yr BP by analyzing the stable carbon and oxygen isotope records of 46 Tegillarca granosa shells collected from archaeological sites in Tainan Science Park. It also explores the seasons in which humans collected T. granosa. The stable oxygen isotope values of archaeological T. granosa shells are as follows: the T. granosa collected from Dabenkeng culture(5000-4200 yr BP), NKLE site （Nanguanli East Site） have an average δ13C value of -3.65±1.61‰ (N=182) and an average δ18O value of -2.91±1.34‰; the Niuchouzi culture (4200-3300 yr BP), YHF site （Youxianfang Site） have an average δ13C value of -3.11±1.03‰ (N=132) and an average δ18O value of -2.79±1.17‰; the Dahu culture, Dahu Phase(3300-2800 yr BP), SOS （Shousha Site） site have an average δ13C value of -2.85±1.06‰(N=145) and an average δ18O value of -2.97±1.49‰; the Dahu culture, Wushantou Phase (2800-2000 yr BP), WCS site（Wangjia South Site）and CKT2 site（Qigandi 2 Site） have an average δ13C value of -2.53±1.33‰(N=559) and an average δ18O value of -3.02±1.37‰; the Niaosong culture, Niaosong Phase(1400-1000 yr BP), MCW（Muzha WestSite）and CKT（Qigandi Site）sites have an average δ13C value of -1.77±1.44‰(N=471) and an average δ18O value of -3.19±1.34‰; the Siraya culture(500-300 yr BP), SN（Shenei Site）site have an average δ13C value of -2.91±1.10‰ (N=636；劉冠辰，2012) and an average δ18O value of -3.45±1.52‰; Han Chinese culture (300 yr BP to present), MC（Muzha Site）, TT（Titang Site） , PTT（Pizitou Site） and WC（Wangjia Site） sites have an average δ13C value of -2.45±1.14‰ (N=1465) and an average δ18O value of -2.91±1.66‰. The stable carbon isotope values of T. granosa from different cultural phases show significant differences, which are likely related to changes in the δ13CDIC of the water. The δ18O average values from the Dabenkeng culture to the Niuchouzi culture, Dahu culture, Dahu Phase, Dahu culture, Wushantou Phase, and Niaosong culture, Niaosong Phase are all around -3‰, with no significant differences. In the Siraya culture, the δ18O values decreased by 0.26‰, suggesting that the climate may have become warmer/wetter. In the Han Chinese culture, the δ18O values increased by 0.54‰, indicating that the climate may have become colder/drier. There is no significant difference between the modern Han Chinese culture and the present, with values around -3‰. The winter δ18O values of T. granosa from the Dabenkeng culture to the Niuchouzi culture, Dahu culture, Dahu Phase, and Dahu culture, Wushantou Phase shows no significant differences. The Niaosong culture, Niaosong Phase shows a decrease of 0.27‰ in winter δ18O values, indicating potentially higher winter temperatures. The Siraya culture shows no significant change in winter δ18O values. The Han Chinese culture shows an increase of 0.71‰ in winter δ18O values, suggesting potentially lower winter temperatures. According to the aragonite oxygen isotope and temperature equation, the winter temperatures during the Han Chinese culture were 1.6-2°C lower than those from 5000 to 300 yr BP and were 2.3°C lower than present temperatures. This suggests that T. granosa collected from Han Chinese culture may have recorded the Little Ice Age, a cooling period of north hemisphere. Additionally, the summer lower δ18O values of T. granosa shells collected from Dahu culture, Dahu Phase and Han Chinese culture indicate that the Little Ice Age and the period from 3,300 to 2,800 yr BP may have experienced higher summer rainfall, which may be related to typhoons. The oxygen isotope values of T. granosa might reflect the season in which the shells were collected. At NKLE site of Dabenkeng Culture, T. granosa was primarily harvested in the spring (67%; N=3). At YHF site of Niuchouzi Culture, T. granosa was mainly harvested in the spring (67%; N=3), followed by winter (33%). At SOS site of Dahu Culture, T. granosa was harvested mainly in the spring (100%; N=2). At WCS site of Dahu Culture,Wushantou phase, T. granosa was primarily harvested in the summer (75%; N=4), followed by autumn (25%). At the CKT2 site, T. granosa was harvested mainly in the winter and spring (80%; N=5). At MCW site of Niaosong Culture, Niaosong phase, T. granosa was harvested in the autumn (100%; N=1), and at CKT site, it was mainly harvested in the spring (67%; N=6). At SN site of Siraya Culture, T. granosa was primarily harvested in the autumn (40%; N=53), followed by summer (32%). At Han Chinese Culture, T. granosa was harvested mainly in the spring (100%; N=3) at MC site, in the summer (80%; N=5) at TT site, in the winter (80%; N=5) at the PTT site, and mainly in the spring (60%; N=5) at the WC site. Overall, humans were more commonly harvesting T. granosa in the spring and summer over the past 5000 B.P..
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血蚶, 穩定碳氧同位素, 季節性, 臺南科學園區考古遺址, Tegillarca granosa, Stable carbon and oxygen isotopes, Seasonality, Tainan Science Park Archaeology