青岛近海生物气溶胶中总微生物的分布特征

Distribution of Total Microbes in Atmospheric Bioaerosols in the Coastal Region of Qingdao

为了解生物气溶胶中总微生物浓度的月季分布和粒径分布特征,于2016年9月~2017年7月期间在青岛近海连续采集了大气生物气溶胶分级样品,并利用DAPI染色-荧光显微镜计数方法测定了生物气溶胶中总微生物浓度.结果表明,采样期间青岛近海生物气溶胶中总微生物浓度范围为1. 86×105~2. 54×10^6cells·m^-3,平均值为(6. 84±4. 83)×105cells·m^-3.大气中总微生物浓度的季节变化为春季和冬季较高,夏季较低,秋季最低,统计分析显示秋季和春季、夏季大气中总微生物浓度具有明显的季节变化差异(P <0. 05).生物气溶胶中总微生物月均浓度在2. 65×10^5~1. 12×106cells·m^-3之间,最高值出现在2017年2月,最低值出现在2016年9月. 2015~2017年青岛秋冬季大气中总微生物浓度一日中变化较大,但并未呈现出明显的日变化规律(P> 0. 05).生物气溶胶中总微生物的粒径分布呈现偏态分布,> 7. 0μm粒径所占比例最高,可达20. 5%~27. 3%;粒径分布随月份不同而有变化,呈现双峰分布和偏态分布两类.相关性分析显示,总微生物浓度与AQI、CO、PM2.5和PM10等因子呈显著正相关(P <0. 05),与温度、风速和风向等气象因素以及NO2、SO2和O3等因子无显著相关(P> 0. 05).多元线性回归模拟结果显示,生物气溶胶总微生物浓度中20. 6%的变化与相对湿度和PM2.5相关.

In order to determine the concentrations and size distributions of total airborne microbes in atmospheric bioaerosols,bioaerosol samples were collected in the coastal region of Qingdao,China,from Sep. 2016 to Jul. 2017 using size-fractionated bioaerosol samplers. The concentrations of total airborne microbes were then measured using an epifluorescence microscope after staining with DAPI( 4’,6-diamidino-2-phenylindole). The results showed that the concentrations of total airborne microbes were in the range of 1. 86 × 10^5-2. 54 × 106 cells·m^-3 in Qingdao during the sampling period,with an average of( 6. 84 ± 4. 83)× 105 cells·m^-3.The concentrations of total airborne microbes showed seasonal variation,with the highest values occurring in spring and winter,and the lowest values in summer and fall. Statistical analysis showed that the concentrations of total airborne microbes in autumn had a significant seasonal difference with spring and summer( P < 0. 05). The monthly averaged concentrations of total airborne microbes ranged from 2. 65 × 10^5 cells·m^-3 to 1. 12 × 10^6 cells·m^-3,with the highest values in Feb. 2017 and the lowest in Sep. 2016. Total microbe concentrations also varied greatly over a diurnal timescale in fall and winter during the period of 2015 to 2017,but this variation was not statistically significant( P > 0. 05). Overall,the size distribution of total airborne microbes was skewed,with the highest ratio occurring at > 7. 0 μm with a ratio of 20. 5%-27. 3%. The monthly averaged size distribution of total airborne microbes varied between months,showing two main distribution types,specifically bimodal and skewed patterns,respectively. Spearman’s rank correlation analysis showed that the AQI and the concentrations of CO,PM2.5,and PM10 had a significant positive correlation with the concentrations of total airborne microbes( P < 0. 05),while air temperature,wind speed and direction,NO2,SO2,and O3 were not significantly correlated with the airborne microbe concentration during the sampling period( P > 0. 05). Multiple linear regression showed that 20. 6% of the variation in the total microbe concentrations in bioaerosols correlated with relative humidity and PM2.5.