广州市酸雨成分及其相关分析

Acid rain composition and its correlation analysis at Guangzhou

分析了2003年11月-2004年10月广州市龙洞79次降雨的化学组分及其各组分之间的相关关系。得出:(1) 观测期间总降雨量1359.8,单次降雨的pH值在3.22-7.29之间,平均4.83;以pH<5.6为酸雨的临界值,则酸雨频率占降雨次数的77.2%2或占降雨量的81.5%;(2)广州降水的化学组成以SO42-、Cl-和NO3-为主要阴离子,阳离子中以Ca2+、NH4+、Na+所占比例较大;(3)广州地区酸雨属硫酸型,降雨中的SO42-、NO3-、PO43-、Cl-、NH4+、K+、Na+、Ca2+、Mg2+ 离子浓度分别为0.150,0.045,0.002,0.163,0.058,0.006,0.013,0.083和0.007 mol·L-1,单次降雨的SO42-/NO3-比值在0.42- 17.6之间,年平均为3.33,该值比西南地区相应值低许多,而且与同一地点5年前测定的结果相比较,SO42-/NO3-比值有变小的趋势,说明广州地区NOx排放量高逐渐增加;(4)广州地区酸雨有着明显的季节变化规律,春、夏、秋季酸雨比较严重,冬季酸雨较少出现,这与西南地区的重庆(冬季酸雨较春季严重)酸雨季节规律相反;(5)通过SPSS统计分析得出,雨量与各化学组分含量成负相关,说明雨量对大气污染物质的稀释作用;酸雨各化学成分之间存在着一定的相关性,如SO42-与Ca2+,NO3-与NH4+,K+与Na+、Mg2+离子,Na+与Mg2+等都存在显著的正相关,利用这种相关可以建立某些酸雨成分的预测模型。

Based en the rainfall measurement of 79 rain events and the chemical composition determination of rainwater at Guangzhou＇s Longdong from November 2003 to October 2004, the acid rain frequency, chemical composition, and its correlation were studied in the paper. The results showed that： （1） Total amount of rainfall was 1359.8 mm during the monitoring period. The pH values varied from 3.22 to 7.29 and with an average of 4.83. The frequency of acid rain （pH〈5.6） is 77.2%, and the amount of acid rain accounts for 81.5% of total rainfall. （2） Acid rainwater takes SO42, CI and NOr as main anion, and has high concentration of Ca^2＋, NH4^＋ and Na^＋. （3） The acid rain at Guangzhou belongs to sulphate-dominated type. The concentration of SO4^2-, NO3^-, PO4^3-, Cl^-, NH4^＋, K^＋, Na^＋, Ca^2＋ and Mg^2＋ in rainwater are 0.150, 0.045, 0.002, 0.163, 0.058, 0.006, 0.013, 0.083 and 0.007 mol· L^-1, respectively. The SO4^2-/NO3^- ratios vary from 0.42 to 17.6, with an average of 3.33, which is much lower than that in southwest China. And the ratio is also less than that measured 5 years ago in the same place. It indicates that the high NOx emission at Guangzhou is a severe environmental threat. （4） There is obvious seasonal variation in rainwater chemistry at Guangzhou, it is that acid rain is more serious in spring, summer and autumn but not in winter. That is the reverse of what observed at Chongqing of southwest China, where acid rain being more serious in winter than in spring. （5） According to the SPSS analysis of measured data, there is a negative relation between rainfall and concentration of each of major element composition, which can illuminate the dilution effect of atmospheric pollutants by rainwater. There is also certain correlation among the chemical compositions of acid rain, such as significant positive relationships between SO4^＋2- and Ca^2＋, NO3^- and NH4^＋, K^＋ and Na^＋/Mg^2＋, Na^＋ and Mg^2＋, respectively.