黑龙江连环湖近现代沉积速率及粒度反映的气候干湿变化  

Modern Sedimentation Rates and Dry-Humid Change Inferred from Grain Size Records in Lianhuan Lake of Heilongjiang Province

作　　者：孙清展[1] 臧淑英[1] 肖海丰[1] 

机构地区：[1]黑龙江省普通高等学校地理环境遥感监测重点实验室,哈尔滨师范大学,黑龙江哈尔滨150025

出　　处：《地理与地理信息科学》2013年第3期119-124,共6页Geography and Geo-Information Science

基　　金：国家自然科学基金项目(41030743;40972115);黑龙江省研究生创新科研项目(YJSCX2012-189HLJ)

摘　　要：通过对连环湖沉积物柱芯YCHB样品的放射性核素137 Cs和210 Pb测验结果进行研究,表明该柱芯137 Cs自1954年初次沉降以来存在1963年、1975年和1986年3个比较突出的蓄积峰,获得连环湖沉积物记录的137 Cs相应时标年份到采样年份(2010年)的平均沉积速率分别是0.170g/cm2.a-1、0.072g/cm2.a-1、0.054g/cm2.a-1及0.051g/cm2.a-1。借助210PbCRS计年模式,发现连环湖过去176年间的沉积速率是波动的,先升高后降低是其总体趋势,这种波动的沉积环境可能与人类在连环湖地区相应历史时期的活动有着密不可分的关系。探讨了两种计年结果差异产生的可能原因。比较分析了当地年均降雨量与沉积物柱芯YCHB对应时段颗粒的中值粒径之间的关系,发现该地区的降雨量和连环湖沉积物粒度的中值粒径(d(50))在受到人类活动影响较少的情况下表现出较好的相关性,即同步波动性良好。在针对湖泊沉积高分辨率、短时间尺度(年际、10a)的研究中,沉积物粒度的中值粒径是指示湖区降雨量变化的有效指标。Based on radionuclide dating （210 Pb and137 Cs） in the sediment core of the Lianhuan Lake, Heilongjiang Province of China, the authors calculated the sedimentation rates in the past 176 years. The vertical profile of 137 Cs has three obvious peaks in the core corresponding to 1963,1975 and 1986, since the onset of 137 Cs fallout in 1954. Using the dating of the 137 Cs peaks, the four time-averaged accumulation rates of the Lianhuan Lake were 0. 170 g/cm^2·a^-1 ,0. 072 g/cm^2·a^-1 ,0. 054 g/cm^2·a^-1 and 0. 051 g/cm^2·a^-1 , respectively. Four stages with different accumulation rates in YCHB sediment core indicated a slower process since the onset of atmospheric nuclear weapons testing in the 1954. According to the result of 210pb （CRS） dating in YCHB, which is fluctuation in the past 176 years, presents on the overall increase at first and then decrease trend, which might be relat- ed to human activities during different historical periods. Compared with the local rainfall in the past 50 years with sediment grain size in the region of Lianhuan Lake, it is found that under the circumstances of less intervention of human activities, there was an obvious variation trend in the sediment grain size with the fluctuations of rainfall. All these findings indicate that there is a positive correlation between grain size and the fluctuations of rainfall. This shows that sediment grain size could reflect the rainfall changes trend at a short time-scale and high resolution investigations, i. e. larger sediment grain size reflected more rainfall and wetter climate while smaller sediment grain size reflected less rainfall and drier climate.

关 键 词：放射性核素 沉积速率 粒度 气候干湿 连环湖 

分 类 号：P512.2[天文地球—地质学]