福建茫荡山春季大气、 雨水和雾水甲醛观测研究

2009年3～4月在福建省茫荡山采用2,4-二硝基苯肼(DNPH)高效液相色谱(HPLC)法采集并检测了大气、雨水和雾水样品中的甲醛浓度.研究发现茫荡山大气、雨水和雾水中甲醛浓度均值分别为4.0×10-10、2.19μmol/L和2.94μmol/L,均属于低浓度水平;根据以往研究阐述了甲醛在液相中存在水解和与S(Ⅳ)的反应等多种化学反应过程,进而使甲醛在液相中的溶解度高于理论值的现象;并通过雨水和雾水的液相甲醛浓度和对应的气态浓度以及采样温度分别计算得到现场实测亨利系数Hme和有效亨利系数H*,比较Hme和H*的大小发现,茫荡山地区雨水和雾水中甲醛液相实际浓度均高于理论浓度,与文献研究一致;并进一步发现,茫荡山雾水中Hme/H*高于雨水,从而验证了雾水甲醛浓度略高于雨水的这一检测结果;茫荡山地区春季雨雾丰富,促使该地区的湿沉降成为甲醛去除的重要途径.

Observational Study of Formaldehyde in Air, Rain and Fog Water at a Site on the Mangdang Mountain of Fujian, China

Through 2,4-dinitrophenylhydrazine (DNPH) high-performance liquid chromatography (HPLC) method, the levels of formaldehyde in ambient air, rain and fog samples were measured in Mangdang Mountain, Fujian Province, from March to April 2009. The average concentrations of formaldehyde in ambient air, rain and fog are 4.0 x 10(-10), 2.19 micromol/L and 2.94 micromol/L, respectively. Based on previous researches, this study described formaldehyde hydrolysis and reacting with S(IV) and other chemical reaction processes in liquid phase, explaining the phenomenon that the solubility of formaldehyde in the liquid phase is higher than the theoretical value. On-site measured Henry coefficients (Hme) and the effective Henry coefficients (H*) were derived from concentration of formaldehyde in ambient air, rain and fog samples and references. Comparing Hme and H*, this study found that the measured liquid phase concentrations of formaldehyde are higher than the theoretical concentrations, consistent with the references. The further founding is that Hme/H* in fog is higher than in rain, proving the result of Mangdang Mountain that the concentration of formaldehyde in fog is higher than in rain. Considering the climatic characteristics of Mangdang Mountain in spring, the wet deposition of formaldehyde is an important way in this area.