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污染控制技术及原理

Metal elements and water-soluble anion concentrations in winter fog water in Nanjing

基金项目：国家自然科学基金项目(No.40775012);气象灾害省部共建教育部重点实验室项目(No.KLME060208);江苏省高校自然科学重大基础研究项目(No.08KJA170002);公益性行业(气象)科研专项(No.GYHY200706026);江苏省“青蓝工程”资助

樊曙先
1. 南京信息工程大学气象灾害省部共建教育部重点实验室, 南京 210044; 2. 南京信息工程大学中国气象局大气物理与大气环境重点开放实验室, 南京 210044

摘要：2007-11-15～2007-12-31期间在南京北郊南京信息工程大学设立采样点,对出现的6次浓雾过程进行了分时段雾水样品采集,并使用ICS-2000离子色谱仪和IRISIntrepidⅡ等离子体发射光谱仪测定了雾水中5种水溶性阴离子和14种金属元素浓度.结果表明,南京6次浓雾过程雾水pH值在4.64～6.88之间;水溶性阴离子平均浓度以SO₄^2-最高(2864.9μmol·L^-1),其次是Cl^-(1584.4μmol·L^-1)和NO₃^-(736·0μmol·L^-1);含量较高的金属元素有Ca、K、Na、Mg、Al和Zn;雾水重金属元素Cu、Ni、Pb、Cd和Cr的平均浓度分别为2.30、1.46、0.42、0·41和0.37μmol·L^-1;雾水金属元素浓度在雾的初始时段表现较高,随着雾的持续发展出现不同程度降低,但日出后的上班早高峰时段又出现很明显的升高;雾水NO₂^-浓度值表现为夜间浓度较高而日出后浓度很低或消失,夜、昼变化非常大;通过对比雾水和雨水pH平均值发现,雾水pH平均值是6.20,雨水pH平均值为4.91,小于酸雨指标值5.6,酸度较强;雾水电导率是雨水的10.5倍,雾水的重金属元素Cd、Cr、Ni、Cu、Pb以及强致酸水溶性阴离子SO₄^2-、NO₃^-、Cl^-的浓度均远远高于雨水,说明雾区大气环境的污染程度比降雨天气更高.

Abstract：Fog water samples during six heavy fog events were collected at Nanjing University of Information Science and Technology(NUIST) from 15 November 2007 to 31 December 2007. Concentrations of five water-soluble anions and fourteen metal elements were detected by ion chromatography and plasma emission spectrometry. The results showed that the pH values ranged from 4.64 to 6.88 among these fog water samples. The average SO₄^2- anion concentration(2864.9μmol·L^-1) was the highest,followed by Cl^-(1584.4μmol·L^-1) and NO₃^-(736.0μmol·L^-1). The average concentration of heavy metal elements Cu,Ni,Pb,Cd and Cr were 2.30,1.46,0.42,0.41 and 0.37 μmol·L^-1 respectively while the Ca,K,Na,Mg,Al and Zn concentrations were much higher. The concentration of metal elements in fog water was high at the initial fog stage,then decreased with the fog development,but increased significantly after sunrise during the peak traffic period. Obvious diurnal variation of NO₂^- was manifested as higher values at night,but very low or undetectable levels after sunrise. The average pH of fog water(6.20) was higher than rain water(4.91),but the conductivity of fog water was 10.5 times higher than that of rain water. The concentration of heavy metal elements(Cd,Cr,Ni,Cu and Pb) and water-soluble anions(SO₄^2-,NO₃^-,Cl^-) in fog water was far higher than rain water. Therefore the air pollution in fog areas was higher than on rainy days.