桂林岩溶区大气降水的化学特征分析

2009年1月至2010年12月期间,对处于岩溶区的桂林市降水进行了连续采样测试分析.研究结果表明:(1)桂林市区降水的pH平均值为4.83,降水的电导率平均值为65 μS/cm,SO42-、NO3-和Ca2+、NH4+分别是最主要的阴阳离子.(2)桂林市降水各主要离子含量、降雨量和电导率表现出明显的季节差异,其中Ca2+、Mg2+含量在夏、冬季较高,春、秋季较低.(3)降雨量和TDS呈现出良好的负相关关系,SO42-和NO3-以及Ca2+和Mg2+之间则具有较好的正相关关系.(4)2009-2010年与1994-1995年相比,降水中的离子含量增加了1.16倍,降水的pH值有所增高,但仍在酸雨范围之内.在桂林酸雨形成中,降水的NO3-贡献明显增强.(5)通过2012年3月1-6日连续6天的降水监测,发现pH、降雨量和电导率三者呈现出良好的相关性.

Analysis on the chemical characteristics of the atmospheric precipitation in Guilin

Precipitation samples are collected and analyzed from January 2009 to December 2010 in the Guilin, Guangxi. The results show that （1） the pH value and the conductivity are 4. 83 and 65 S/cm respectively, the major anions are SO4^2- and NO3^-, the major cations Ca^2＋ and NH4^＋ in the rainwater samples of Guilin; （2） major ion content, rainfall and conductivity assumes obvious seasonal variations, and among them the Ca^2＋ concentration is higher in summer and autumn, lower in spring and winter; （3） rainfall and TDS show good negative correlation, SO4^2- and NO3^-, and Ca^2＋ and Mg^2＋ have good positive correlation; （4） in comparing the situations in the year of 2009-2010 to 1994-1995, the ion in the precipitation has increased by 1.16 times and pH increased to some extent, the rain still belongs to acid rain, and the contributing rate of the NO3^- in the precipitation for the formation of acid rain in Guilin has obviously enhanced; （5）through continuous monitoring on rainfall of Guilin during 1 to 6, Mar. 2012, it is found that pH, conductivity and precipitation appear good correlation.