PCA、DCA和CCA分析显示,可以利用英国威尔士地区34个湖泊表层沉积物的现代硅藻组合和pH数据,建立硅藻-pH转换函数.根据RMSE和残差分析,选用了WA_Cla_X和WAPLS_C2_X模型,同时选取WA_Cla作为对照.我们在Llyn Hir湖中心钻取岩芯,对顶部14.5cm进行了化石硅藻种群组合的分析,利用这些资料,根据这三个硅藻-pH转换函数模型,定量重建了该湖1956-1995年pH的变化过程.结果显示,1985年为了改善该湖酸化状况,向湖中施加石灰引起湖水pH明显增高,这种显著效果维持了六年,此后逐渐减弱乃至消失.利用硅藻-pH转换函数重建的湖泊pH变化结果与湖泊pH实际监测结果相当吻合,说明了虽然施加石灰可在较短时期内减弱湖泊酸化程度,但是不能根治湖泊酸化.

In terms of principle components analysis (PCA), detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA), a diatom-pH transfer function could be reconstructed by using the modern diatom data and pH from 34 lakes in Wales. In light of root mean square error (RMSE) and residuals results of the experiments, x-validated weighted averaging with classical deshrinking (WA_Cla_X) and x-validated weighted averaging partial least squares component 2 (WAPLS_C2_X) were selected for pH reconstruction with WA with classical deshrinking (WA_Cla) as comparison. According to these diatom-pH transfer functions, the fossil diatom in the sediment were analysed to reconstruct the pH value in Llyn Hir (lake) from 1956 to 1995. It showed that improvement of pH in 1985 was the result of liming by the history record and there was an obvious effect in the following six years but the effect weakened gradually until vanished. Although liming can increase pH in a relatively short period, it cannot eradicate lake acidification.