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对1989-1991年期间,在台湾地区采集的5个湖泊的沉积物岩芯和22个湖泊水库的表层沉积物,进行了沉积物超量210Pb活性的分析,以探讨其沉积速率。其中,小鬼湖沉积物岩芯取部分样品进行14C定年,以与210Pb所得结果比较。结果表明,数千年来,台湾高山湖泊、次高山湖泊的沉积速率相当稳定,除万里池外,大多介于0.06-0.16cm/a之间。火山湖的210Pb活性较一般湖泊高,这是由于火山湖当地安山岩及地下水释出较多的210Pb所致,但这并不意味其沉积速率慢。所以应用210Pb对火山湖沉积物定年时,须作特别修正。平地湖泊目前沉积速率,除了大埔水库高达6.42cm/a外,大多介于0.5—3、2cm/a之间,比高山湖泊的沉积速率高约10-20倍。另外,由水库淤沙资料显示1),历年平均沉积速率都比目前的沉积速率快数倍,其中以石门、白河、乌山头、阿公店4个水库的平均沉积速率较快。
During the period 1989-1991, sediment cores from 5 lakes collected in Taiwan and surface sediments from 22 lakes and reservoirs were analyzed for excess 210Pb activity to investigate their deposition rate. Among them, the small lake sediment core samples taken 14C dating, compared with 210Pb results. The results show that the sedimentation rates of Taiwan’s mountain lakes and sub-alpine lakes have been quite stable for thousands of years, with the exception of Wanli Lake, mostly ranging from 0.06 to 0.16 cm / a. The 210Pb activity of volcanic lakes is higher than that of normal lakes because of the 210Pb released from the local andesite and groundwater in volcanic lakes, but this does not mean that the deposition rate is slow. Therefore, the application of 210Pb volcanic lake sediments dating, special amendments to be made. At present, the sedimentation rate in the plains lakes is mostly between 0.5-3 and 2cm / a except for the Tai Po Reservoir up to 6.42cm / a, which is about 10-20 times higher than that of the mountain lakes. In addition, from the sediment data of reservoir 1), the average sedimentation rate over the years is several times faster than the current sedimentation rate, of which the average sedimentation rate of four reservoirs in Shimen, Shirakawa, Wushantou, and A-gong stores is relatively quick.