Baumgardner D, Raga G B, Grutter M, Lammel G, Moya M
Universidad Nacional Aurónoma de México, Ciudad Universitaria, Mexico City, Mexico.
Sci Total Environ. 2006 Dec 15;372(1):287-98. doi: 10.1016/j.scitotenv.2006.08.044. Epub 2006 Oct 9.
An analysis of atmospheric gases and particles during periods of land and sea breezes in a coastal city in southwest Mexico indicates limited removal of total particle mass by deposition during periods when the air resides over the ocean. The average PM(2.5) mass concentrations for land and sea breeze samples were 25+/-1.0 and 26+/-1.0 microg m(-3), respectively. The average sum of the ion concentrations (NH(4)(+), SO(4)(2-), NO(3)(-), Na(+), Cl(-)) were 10 and 11.8 microg m(-3) for the samples taken during land and sea breeze periods. The average total carbon concentrations were 6.0 and 5.3 microg m(-3) for land and sea breeze periods. The mass of sulfate in particles of ocean origin, 3.3+/-2.8 microg m(-3), is marginally higher than those originating from the land, 2.0+/-0.8 microg m(-3), presumably as a result of the conversion of SO(2) recirculated from the city. The fraction of sulfate, nitrate and ammonium ions in rainwater samples is almost a factor of two higher than the fraction measured on filtered air samples. The rainwater also contains significant concentrations of elemental and organic carbon. This study, although extending over a period of only 15 days, with limited chemical samples, suggests that recirculation of anthropogenic particles from coastal cities should be taken into consideration when diagnosing and predicting air quality in such regions.
对墨西哥西南部一个沿海城市海陆风期间的大气气体和颗粒物进行的分析表明，在空气停留在海洋上空的时期，通过沉降去除的总颗粒物质量有限。陆风和海风样本的平均PM(2.5)质量浓度分别为25±1.0和26±1.0微克/立方米。陆风和海风期间采集的样本中，离子浓度（NH(4)(+)、SO(4)(2-)、NO(3)(-)、Na(+)、Cl(-)）的平均总和分别为10和11.8微克/立方米。陆风和海风期间的平均总碳浓度分别为6.0和5.3微克/立方米。海洋源颗粒物中的硫酸盐质量为3.3±2.8微克/立方米，略高于陆地源的2.0±0.8微克/立方米，这可能是城市中再循环的SO(2)转化的结果。雨水样本中硫酸盐、硝酸盐和铵离子的比例几乎比过滤空气样本中测得的比例高出一倍。雨水中还含有大量的元素碳和有机碳。这项研究虽然仅持续了15天，化学样本有限，但表明在诊断和预测此类地区的空气质量时，应考虑沿海城市人为颗粒物的再循环。
