广州地区雨水化学组成与雨水酸度主控因子研究

采集了广州地区2003-10～2004-09的雨水样品,通过对雨水样品的pH值、主要阴阳离子组成和可溶性有机碳(DOC)的测定,分析了广州地区酸雨的现状以及影响雨水酸度的主要因素等.结果表明,在观测期间,广州地区酸雨频率高达85%;雨水的主要离子组成为NH₄⁺、SO₄^2-、NO₃^-、Ca²⁺、Cl^-和Na⁺,而DOC约占总化学组成的24.0%;雨水酸度的主要控制离子还是SO₄^2-,但NO₃^-对雨水酸度的影响越来越大;同时,水溶性有机酸对雨水酸度的贡献也很明显.另外,来自扬尘中高浓度的碱性含钙化合物也对雨水酸度有明显的中和作用.

Study on Ionic Composition of Rainwater at Guangzhou and the Primary Factors of Rainwater Acidity

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^-, SO₄^2-, NH₄⁺ and Ca²⁺ are dominant ions in the rainwater. DOC approximately consisted of 24.0% of total chemical components. Although SO₄^2- 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.