Combustion-derived and land-plant-derived polycyclic aromatic hydrocarbons （PAHs） have been investigated by using the GC-MS analysis in an ancient soil profile from Jinluojia （金罗家） archaeological site at Mache...Combustion-derived and land-plant-derived polycyclic aromatic hydrocarbons （PAHs） have been investigated by using the GC-MS analysis in an ancient soil profile from Jinluojia （金罗家） archaeological site at Macheng （麻城）,Hubei （湖北） Province,Central China.Retene,cadalene and simonellite were proposed to be derived from contemporary land plants.The pyrolytic PAHs identified include fluoranthene,pyrene,benzofluoranthenes,benzo[e]pyrene and benzo[a]pyrene.The distribution of these pyrolytic PAHs varies with depth,displaying a pattern different from the land-plant-derived compounds.On the basis of the parameter diagnostic of sources and the distribution patterns,these pyrolytic PAHs were demonstrated to be of combustion origin,rather than petrogenic origins,combustion of petroleum products and coal,or a post-depositional process such as pedogenesis or leaching.These combustion-induced PAHs were believed to result from both natural processes and anthropogenic activities.Two episodes of the elevated content of pyrolytic PAHs and charcoal fragments were identified in Ming-Qing （明清） Dynasty and late Xizhou （西周） to early Dongzhou （东周） Dynasty,inferring the occurrence of two enhanced paleofires.The two enhanced paleofire episodes were found in association with the two cold and dry paleoclimate and two episodes of enhanced abundance of charcoal fragments,inferring a dominance of the natural processes triggering the enhanced paleofire.The two periods of paleofire were also characterized by the frequent and enhanced anthropogenic activities such as war fights,likely suggesting the occurrence of anthropogenic contributions.展开更多
炭屑作为植物不完全燃烧的产物,记录了母源植物与古火灾的信息.通过分析大九湖泥炭钻孔中炭屑的形貌特征、浓度及长宽比,并与藿类通量、孢粉等生物源古环境指标进行对比,以揭示炭屑指标的古火灾和古环境意义.结果表明:炭屑的母源信息可...炭屑作为植物不完全燃烧的产物,记录了母源植物与古火灾的信息.通过分析大九湖泥炭钻孔中炭屑的形貌特征、浓度及长宽比,并与藿类通量、孢粉等生物源古环境指标进行对比,以揭示炭屑指标的古火灾和古环境意义.结果表明:炭屑的母源信息可由其几何形态、表面纹理及气孔结构来进行识别.炭屑的浓度与长宽比具有明显的阶段性变化,反映了古火灾的强度和主要燃烧生物材质的变化.主要分为两个阶段,全新世中期约8.5~4.3 ka B.P.期间,炭屑浓度普遍较高,与气候干旱相联系,古火灾事件与干旱高峰一致;但7.3~7.0 ka B.P.时段内炭屑浓度呈现低值,频繁降水制约了古火灾的发生.全新世晚期约4.3 ka B.P.以来,古气候由干旱转为湿润,炭屑含量波动性下降;但在3.6 ka B.P.和2.5 ka B.P.左右,波动异常明显,表明湿润背景下的干旱事件与火灾频发密切相关.据此,炭屑可作为与高山泥炭地干旱化相联系的古火灾代用指标.展开更多
火事件的发生与气候变化以及植被变化密切相关,系统性地研究全新世火活动的时空演化规律,可以更清晰地理解火活动机制与区域性气候、植物变化的关联,同时有助于预测未来火的演化趋势。为了解安达曼海周边地区火灾活动的演化以及可能的...火事件的发生与气候变化以及植被变化密切相关,系统性地研究全新世火活动的时空演化规律,可以更清晰地理解火活动机制与区域性气候、植物变化的关联,同时有助于预测未来火的演化趋势。为了解安达曼海周边地区火灾活动的演化以及可能的驱动因素,以安达曼海南部的海洋钻孔ADM-C1为研究材料,对其全新世以来的炭屑记录进行深入分析,并综合安达曼海周边地区其余的5个炭屑记录,重建了全新世以来安达曼海周边地区火灾活动的演变过程。研究表明,尽管点火、火灾天气和植被组成在各地不尽相同,导致火灾发生频率在区域和地方范围有所不同,但在广泛的气候变化背景下,全新世安达曼海周边各地的火事件发生频率变化具有广泛同步性。全新世安达曼海周边的火灾活动发生频率受到区域性植被和降水变化影响,并最终受控于印度夏季风强度的变化。与末次冰消期相比,12.0~9.0 ka BP安达曼海周边区域火灾活动的发生频率呈下降趋势,反映了印度夏季风降水逐步增加以及木本植物含量逐渐上升的区域环境;9.0~5.0 ka BP较低的区域火灾活动发生频率同时受到较高的印度夏季风降水量和区域木本植物含量的制约;5.0 ka BP后高频的区域火灾活动更多反映了印度夏季风降水的降低。此外,研究结果还表明全新世安达曼海周边区域火灾活动发生频率与厄尔尼诺—南方涛动强度、印度洋偶极子位相和热带辐合带位置的变化相关。展开更多
基金supported by the National Natural Science Foundation of China (Nos. 40930210,40621002)the 111 Project (No. B08030)
文摘Combustion-derived and land-plant-derived polycyclic aromatic hydrocarbons （PAHs） have been investigated by using the GC-MS analysis in an ancient soil profile from Jinluojia （金罗家） archaeological site at Macheng （麻城）,Hubei （湖北） Province,Central China.Retene,cadalene and simonellite were proposed to be derived from contemporary land plants.The pyrolytic PAHs identified include fluoranthene,pyrene,benzofluoranthenes,benzo[e]pyrene and benzo[a]pyrene.The distribution of these pyrolytic PAHs varies with depth,displaying a pattern different from the land-plant-derived compounds.On the basis of the parameter diagnostic of sources and the distribution patterns,these pyrolytic PAHs were demonstrated to be of combustion origin,rather than petrogenic origins,combustion of petroleum products and coal,or a post-depositional process such as pedogenesis or leaching.These combustion-induced PAHs were believed to result from both natural processes and anthropogenic activities.Two episodes of the elevated content of pyrolytic PAHs and charcoal fragments were identified in Ming-Qing （明清） Dynasty and late Xizhou （西周） to early Dongzhou （东周） Dynasty,inferring the occurrence of two enhanced paleofires.The two enhanced paleofire episodes were found in association with the two cold and dry paleoclimate and two episodes of enhanced abundance of charcoal fragments,inferring a dominance of the natural processes triggering the enhanced paleofire.The two periods of paleofire were also characterized by the frequent and enhanced anthropogenic activities such as war fights,likely suggesting the occurrence of anthropogenic contributions.
文摘炭屑作为植物不完全燃烧的产物,记录了母源植物与古火灾的信息.通过分析大九湖泥炭钻孔中炭屑的形貌特征、浓度及长宽比,并与藿类通量、孢粉等生物源古环境指标进行对比,以揭示炭屑指标的古火灾和古环境意义.结果表明:炭屑的母源信息可由其几何形态、表面纹理及气孔结构来进行识别.炭屑的浓度与长宽比具有明显的阶段性变化,反映了古火灾的强度和主要燃烧生物材质的变化.主要分为两个阶段,全新世中期约8.5~4.3 ka B.P.期间,炭屑浓度普遍较高,与气候干旱相联系,古火灾事件与干旱高峰一致;但7.3~7.0 ka B.P.时段内炭屑浓度呈现低值,频繁降水制约了古火灾的发生.全新世晚期约4.3 ka B.P.以来,古气候由干旱转为湿润,炭屑含量波动性下降;但在3.6 ka B.P.和2.5 ka B.P.左右,波动异常明显,表明湿润背景下的干旱事件与火灾频发密切相关.据此,炭屑可作为与高山泥炭地干旱化相联系的古火灾代用指标.
文摘火事件的发生与气候变化以及植被变化密切相关,系统性地研究全新世火活动的时空演化规律,可以更清晰地理解火活动机制与区域性气候、植物变化的关联,同时有助于预测未来火的演化趋势。为了解安达曼海周边地区火灾活动的演化以及可能的驱动因素,以安达曼海南部的海洋钻孔ADM-C1为研究材料,对其全新世以来的炭屑记录进行深入分析,并综合安达曼海周边地区其余的5个炭屑记录,重建了全新世以来安达曼海周边地区火灾活动的演变过程。研究表明,尽管点火、火灾天气和植被组成在各地不尽相同,导致火灾发生频率在区域和地方范围有所不同,但在广泛的气候变化背景下,全新世安达曼海周边各地的火事件发生频率变化具有广泛同步性。全新世安达曼海周边的火灾活动发生频率受到区域性植被和降水变化影响,并最终受控于印度夏季风强度的变化。与末次冰消期相比,12.0~9.0 ka BP安达曼海周边区域火灾活动的发生频率呈下降趋势,反映了印度夏季风降水逐步增加以及木本植物含量逐渐上升的区域环境;9.0~5.0 ka BP较低的区域火灾活动发生频率同时受到较高的印度夏季风降水量和区域木本植物含量的制约;5.0 ka BP后高频的区域火灾活动更多反映了印度夏季风降水的降低。此外,研究结果还表明全新世安达曼海周边区域火灾活动发生频率与厄尔尼诺—南方涛动强度、印度洋偶极子位相和热带辐合带位置的变化相关。
