中文摘要：

为了解浙江宁波天童地区降水的化学特征、离子来源及酸性降水的成因,于2010年3月—2011年2月在该地区采集了90个降水样品,并运用离子色谱法分析其化学组分.结果显示,天童地区降水的酸化频率和酸化程度非常高,酸雨频率为97%,雨量加权pH平均值为4.37,离子浓度的大小顺序为SO24-〉NH4＋〉NO3-〉Ca2＋〉Cl-〉Na＋〉Mg2＋〉K＋〉F-,降水较清洁;降水pH值和各离子含量存在明显的季节变化,总体表现为冬、春季污染程度高于夏、秋季;SO24-/NO3-的浓度比值为1.9,表明该地区酸雨类型为硫酸和硝酸复合型;SO24-、NO3-、NH4＋和部分Ca2＋主要来自人为污染源,Na＋、Cl-和大部分Mg2＋主要来自海洋源,K＋和大部分Ca2＋则主要来自地壳源,海洋对天童地区降水离子组分影响较大,但对降水酸度影响并不显著;NH4＋与SO42-（r=0.90）、NO3-（r=0.88）的相关性分别大于Ca2＋与SO24-（r=0.67）、NO3-（r=0.73）的相关性,且NH4＋/Ca2＋的浓度比值为1.47,说明NH4＋对降水酸性的中和作用大于Ca2＋,与我国其他城市降水相比,天童地区降水中的碱性离子,尤其是Ca2＋浓度较低,从而导致降水酸度高于北方地区和西南其他地区.

英文摘要：

To explore the chemical characteristics and the causes of acid rain,90 rain samples were collected from Mar.2010 to Feb.2011 in Tiantong region,Zhejiang Province,and measured by ion chromatography.The results showed that mean pH in precipitation was 4.37,and the acid rain frequency was 97% over the year.The ion concentration followed by the order of SO2-4NH＋4 NO-3 Cl- Ca2＋ Na＋ Mg2＋ K＋F-.There was a pronounced seasonal pattern for pH and ion concentration in precipitation,much more serious pollution in winter and spring than in summer and autumn.Equivalence ratio of SO2-4 to NO-3 was 1.9,indicating that acid rain was dominated by sulfuric-nitric mixed type.Anthropogenic sources contributed most of SO2-4,NH＋4,NO-3 and part of Ca2＋,sea salt was responsible for the presence of Na＋,Cl-and the most amount of Mg2＋,and K＋ and the most fraction of Ca2＋ came from crust.Sea salts posed significant effect on ion concentrations,but little effect on acidity in precipitation.The correlation coefficients of NH＋4 to SO2-4（r=0.90） and to NO-3（r=0.88） were significantly higher than that of Ca2＋ to SO2-4（r=0.67） and to NO-3（r=0.73）,suggesting that NH＋4 can neutralize more significantly the rain acidity than Ca2＋.This could be further confirmed by 1.47 of equivalence ratio of NH＋4 to Ca2＋.Different from other cities,alkaline ions,especially Ca2＋,was lower in the precipitation of Tiantong region,resulting in relatively high rain acidity.