摘要
O of a stalagmite collected from Shihua Cave, 50 km southwest of Beijing is analyzed. The uppermost 2 cm was sampled at about 3-year intervals by a computer-controlled microsampling device. A total of 133 samples were analyzed, covering the last 480 years. A comparison of the δ 18O record with the instrumentally recorded precipitation in Beijing and Tianjin back to 1840 AD shows that high precipitation correlates with negative δ 18O peaks. The long-term δ 18O trend records temperature changes. Between 1620 and 1900 AD, the temperature was cooler than the average value for the 480-year record, corresponding to the Little Ice Age. Temperatures warmer than the average prevailed during 1520-1620 and 1900-present. Superimposed on the long-term trend are about 14 δ 18O cycles of 30-40-year periodicity, with wet periods centered around 1985, 1955, 1910, 1880, 1840, 1800, 1760, 1730, 1690, 1660, 1630, 1600, 1560 and 1530 AD.
O of a stalagmite collected from Shihua Cave, 50 km southwest of Beijing is analyzed. The uppermost 2 cm was sampled at about 3-year intervals by a computer-controlled microsampling device. A total of 133 samples were analyzed, covering the last 480 years. A comparison of the δ 18O record with the instrumentally recorded precipitation in Beijing and Tianjin back to 1840 AD shows that high precipitation correlates with negative δ 18O peaks. The long-term δ 18O trend records temperature changes. Between 1620 and 1900 AD, the temperature was cooler than the average value for the 480-year record, corresponding to the Little Ice Age. Temperatures warmer than the average prevailed during 1520-1620 and 1900-present. Superimposed on the long-term trend are about 14 δ 18O cycles of 30-40-year periodicity, with wet periods centered around 1985, 1955, 1910, 1880, 1840, 1800, 1760, 1730, 1690, 1660, 1630, 1600, 1560 and 1530 AD.
基金
theNationalNaturalScienceFoundationofChina (GrantNo .96 15875 )
