2003—2015年北京市观象台酸雨特征及长期趋势分析

Characteristics and Trend Analysis of Acid Rain from 2003 to 2015 in Beijing Meteorological Observatory

利用2003—2015年观象台的酸雨观测资料,统计分析了北京市观象台酸雨分布特征及长期变化趋势。结果表明,北京市观象台降水年均pH值的变化范围为4.34～5.87,北京市观象台酸雨变化分为3个阶段:2003—2005年年均p H值较高,2006年是转折点,年均pH值比2005年下降0.42,2007—2010年的年均pH值均低于4.5,在此期间北京地区已成为重酸雨污染区,2011—2015年pH值呈现较稳定的上升趋势。由于北京地区夏、秋季节温度及湿度均较高,加快了酸雨前体物的转换速率,而冬、春季节干旱少雨,大气中沙尘和颗粒较多,对酸性降水有缓冲作用,所以酸雨发生频率在夏季和秋季明显高于春季和冬季。降水的年均电导率的变化范围为48.8～99.5μS·cm^(-1),年际变化规律不明显,但电导率与降水量存在相关性,总降水量较小的年份,年均电导率偏高;总降水量较大的年份,年均电导率偏低。

By utilizing the observed data of Beijing meteorological observatory lasting from 2003 to 2015, the characteristics and long-term trend of acid rain in Beijing meteorological observatory were analyzed in this paper. The conclusions were as follows, the annual average of pH values varies from 4.34[5.87. Three different periods were obtained according to the pH values： the first period lasted from 2003 to 2005 with high annual average of precipitation pH values, while the year of 2006 was a turning point, with a drop of 0.42 in annual average of precipitation pH values. The annual average of precipitation pH values were lower than 4.5 during 2007-2010, and Beijing were a heavy acid rain pollution area; the trend of precipitation pH values showed upward from 2011 to 2015. Due to the high temperature and humidity in summer and autumn of Beijing, the conversion rate of acid rain precursors was accelerated, Drought and less rain, more dust and particles in the atmosphere in winter and spring of Beijing weakened acidity of rain. Therefore, the frequency of acid rain in summer and fall was significantly higher than that in spring and winter. The annual average conductivity values vary from 48.8 ｜!s ＊ cm-1 to 99.5 ! s -cm-1, with no significant change. There was a correlation between conductivity and precipitation. The average annual value of conductivity was high in the year with little precipitation and vice versa.