中文摘要：

为了解庐山降水的化学特征和酸化趋势,于2011年夏季及2012年春季在庐山进行降水采集,对降水的p H、主要阴阳离子和有机酸进行分析。结果表明,酸性降水出现频率为100%,p H均值为4.44。降水中SO4^2-、NH4^＋、NO3^-和Ca^2＋占总离子的70.1%,降水酸度主要贡献为H2SO457%、HNO325%及有机酸19%。降水的相对酸度较高,在2011年夏季和2012年春季分别为0.47和0.32。而SO4^2-/NO3^-则分别为2.28和2.63。相对于1993年春季,庐山降水酸度趋于降低,SO4^2-、Ca^2＋浓度水平下降明显,而NH4^＋、NO3^-略有升高,HNO3对酸度的贡献增加,降水已由硫酸型污染转成混合型污染。相对于国内其他背景站点,庐山降水酸度较高,但总离子浓度水平较低,因此庐山作为研究中国东南酸雨区的背景站点具有一定的科学意义。

英文摘要：

In order to investigate the chemical characteristics and acidification trend of precipitation at Mount Lushan,precipitation samples were collected during the summer of 2011 and spring of 2012,and p H value and concentrations of major ions and organic acids were analyzed. Results indicated that all precipitation samples had been acidified with the volume weighted mean p H 4.44. The dominant ions of precipitation were SO4^2-,NH4^＋,NO3^-and Ca^2＋,which accounted for70.1% of the total ions. The acidities were mainly attribute to H2SO457%,followed by HNO325% and organic acid 19%. The fractional acidity of precipitation was 0.47 in 2011 and 0.32 in 2012 respectively,while the ratio of SO4^2-/NO3^-was 2.28 and2.63,indicting high acidity. Compared with precipitation in 1993,the acidity tended to reduce,the concentrations of SO4^2- and Ca^2＋ decreased and NH4^＋,NO3^- slightly increased. The increase contribution of HNO3 to acidity put the precipitation pollution type into sulfuric acid- nitrate component. The acidity was found higher and total ions concentration levels lower than other background sites in China,indicating Mount Lushan is a significant background site for acid precipitation researches.