Study on Ionic Composition of Rainwater at Guangzhou and the Primary Factors of Rainwater Acidity
广州地区雨水化学组成与雨水酸度主控因子研究

All rainwater samples were collected during the period Oct.2003 to Sep.2004 and analysed in terms of pH values, major cation, anion composition and soluble organic carbon (DOC). The measurement of pH values shows that 85% of these rain events were acid rain. The ionic composition analysis indicates that NO3-, SO42-, NH4+ and Ca2+ are dominant ions in the rainwater. DOC approximately consisted of 24.0% of total chemical components. Although SO42- remains the dominant acidic ion in term of concentration, NO3- has become very important to the acidity of rainwater and as well as the organic acids. Furthermore, dust sourced Ca2+ appears to play significant role in neutralizing the acidity in rainwater.