青岛市不同空气质量下可培养生物气溶胶分布特征及影响因素

利用Andersen空气微生物采样器采集青岛市不同空气质量下的可培养生物气溶胶,分析了其浓度和粒径分布特征,并利用Spearman’s相关性分析了可培养生物气溶胶浓度和空气质量指数中的颗粒物质量浓度〔ρ(PM₁₀)、ρ(PM_2.5)〕、气体污染物质量浓度〔ρ(O₃)、ρ(SO₂)、ρ(NO₂)〕和气象参数(温度、相对湿度、风速)之间的关系.结果表明:可培养真菌和细菌气溶胶浓度范围分别为133～1 113和13～212 CFU/m3.真菌气溶胶浓度与ρ(SO₂)、ρ(PM₁₀)、ρ(PM_2.5)均呈正相关,而与相对湿度呈显著负相关(P<0.05).细菌气溶胶浓度与ρ(NO₂)、ρ(SO₂)呈负相关,而与ρ(O₃)、温度呈正相关.风速对可培养生物气溶胶浓度的影响较小.以AQI(空气质量指数)中ρ(PM₁₀)为依据,将研究时间段空气质量划分为4个空气污染等级.在不同污染等级下,真菌气溶胶均呈对数正态分布,粒径主要分布于2.1～4.7 μm.低污染时细菌气溶胶呈偏态分布(粒径>4.7 μm),高污染时粒径分布发生改变.初步推断,随着空气污染等级的升高,可培养生物(真菌+细菌)气溶胶总浓度增加,但单位颗粒物上的浓度变化较稳定.ρ(PM₁₀)是影响可培养生物气溶胶浓度及粒径分布的主要因素. 

Size Distribution Characteristics of Culturable Bioaerosols in Relation to Air Quality Levels in Qingdao

Abstract:The concentration and size distribution of culturable fungi and bacteria were studied in Qingdao city at various air quality levels.The culturable bioaerosols were collected by Andersen biological aerosol sampler.The measured results showed that the concentrations of culturable fungi and bacteria were in the ranges of 133-1113 CFU/m3 and 13-212 CFU/m3,respectively.When Spearman’s correlation was used to link the concentrations with levels of criteria air pollutants such as SO₂,PM₁₀,PM_2.5,NO₂ and O₃ as well as meteorological conditions including ambient temperature,relative humidity and wind speed,we found that the fungal aerosol concentrations showed positive correlations with ρ(SO₂),ρ(PM₁₀) and ρ(PM_2.5),but negative correlation with relative humidity.Bacterial aerosols were negatively correlated with ρ(NO₂) and ρ(SO₂),but positively correlated with temperature and ρ(O₃).The influence of wind speed on the concentrations of culturable bioaerosols was negligible.When the size distributions of culturable bioaerosols by number concentration were examined at the four air quality levels proposed by the Ambient Air Quality Standards in China according to the measured PM₁₀ mass concentration,fungal aerosols were mainly distributed in the 2.1-4.7 μm size range and showed a log normal distribution regardless of air quality levels.However,the size distribution of bacteria aerosols showed a skewed distribution,with the maximum value in the size >4.7 μm at low pollution levels.At high pollution levels,their size distributions highly varied.Overall,it seemed that increased loadings of PM₁₀ favored higher number concentrations of culturable bioaerosols,while the ratio of the latter to the former was stable.The influence of PM₁₀ loadings further changed the size distributions of culturable bioaerosols by number concentration.