中文摘要：

经过前处理的石英样品分别在海拔不同的四个地区HE京：50m，银川：1100m，格尔木：2760m，拉萨：3600m）进行了自然光光晒退实验。实验结果表明，经过一定时间的太阳光晒退后，石英Ti心的ESR信号可以回零；北京地区石英Ti心ESR信号回零需要128h，而在拉萨仅需56h。因此，我们推测石英Ti心的ESR信号的光晒退行为与紫外线强度有关，紫外线强度越强，Ti信号回零所需的时间越短。

英文摘要：

Quartz grains were extracted from granite. Bleaching was carried out in four different area chosen for their different altitudes （Beijing, Yinchuan, Germu, Lhasa）, in order to observe their behavior under different intensities of the UV （Ultra violet） component of sunlight. The result of our experiments indicate that the Ti center signal is totally bleachable by the natural sunlight and show that the Ti center signal was reduced to zero after about 128 h in Beijing and after 56 h for Lhasa. We can speculate that different intensity of the UV component of sunlight lead to different minimal time necessary to obtain the total bleaching of the quartz sample.