重庆地区近10年酸雨时空分布和季节变化特征分析

Analysis of Spatio-temporal Distribution and Seasonality of Acid Rain in Chongqing from 1997 to 2006

利用2005年重庆各区县31个观测站降水的pH值资料分析了当年整个地区的降水酸度的空间分布和季节变化特征,并选取中国气象局酸雨观测网中沙坪坝、涪陵、万县、奉节和巴东5个观测站点1997年至2006年的酸雨观测数据,对重庆地区近10年来酸雨的时空分布特征和季节变化情况进行了统计分析。研究结果表明:重庆地区降水酸性和电导率的地区间差异较大,降水酸性的季节变化较明显,冷季(秋、冬)较暖季(春、夏)要强。西南部降水酸性较强,受污染程度也较严重,但没有明显的变化趋势;东北部大多为弱酸性降水,且受污染程度也较轻,但是日趋酸化和污染加重的趋势却较明显,且季节变化尤为明显,其中夏秋两季pH值的明显减小是其近10年来酸化加重的主要原因。涪陵的数据明显不同,酸性降水频率较低,pH值偏高的同时电导率也偏高,2001年前后情况尤为明显,可能受局地因素的影响比较大。

With the data set obtained at 31 meteorological stations in 2005, spatial distribution and seasonality of precipitation acidity over Chongqing area were analyzed. Meanwhile, based on the statistics of long-term data set of 5 acid rain monitoring stations among the above meteorological stations （Shapingba, Fuling, Wanxian, Fengjie and Badong）, the spatio-temporal distribu- tion and seasonality of acid rain in recent 10 years （from 1997 to 2006） were discussed. The re- suits indicate a large discrepancy of acidity and conductivity of precipitation over Chongqing area. The seasonality of precipitation acidity is obvious in Chongqing area as a whole, pH value of pre- cipitation in spring and summer higher than in autumn and winter. The acidity of precipitation in the southwest part of Chongqing is stronger than other parts, and the conductivity also higher. However, there was no significant trend in the acidity and conductivity of precipitation during last 10 years in the southwest part. The precipitation acidity aggravated and conductivity increased significantly in northeast part of Chongqing in recent 10 years, although pH value and conductivi- ty data sets showed the precipitation in this part less polluted. The seasonality of acidity and con- ductivity of precipitation in the northeast part of Chongqing is more pronounced. The trend of the precipitation acidity in the northeast part of Chongqing is mainly caused by the decrease of pH value in summer and autumn. The pH value and conductivity of precipitation at Fuling are much higher than the surrounding areas, suggesting the importance of local influences.