Concentration of bacterial aerosols in response to synoptic weather and land‐sea breeze at a seaside site downwind of the Asian continent
Concentration of bacterial aerosols in response to synoptic weather and land‐sea breeze at a seaside site downwind of the Asian continent
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DOI：
10.1002/2016jd025028
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发表时间：
2016-10
期刊：
影响因子：
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通讯作者：
Kotaro Murata;Daizhou Zhang
中科院分区：
文献类型：
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作者：
Kotaro Murata;Daizhou Zhang
空气传播的细菌是生物气溶胶的一个主要群体，但由于缺乏适当时间分辨率的准确信息，人们对其在大气中的时空变化知之甚少。在这项研究中，我们量化了日本西南海岸一个海边地点春季空气中细菌的浓度和活力，以研究它们与天气天气的关系，天气天气是由中纬度西风流中气旋和反气旋交替控制的。细菌的浓度变化幅度较小，在105 ~ 106 cells m−3量级，而在不同天气条件下，细菌的生存力在23 ~ 96%之间存在显著差异。气旋通过其后方的空气从亚洲大陆带来了细菌。与其他天气条件下的细菌相比，锋后空气中的细菌浓度大，生存力低，与粗粒气溶胶密切相关。相比之下，前额空气中的细菌浓度和活力变化范围较小，并且细菌与气溶胶颗粒数浓度之间没有相关性。在反气旋期间，虽然细菌浓度与前额空气相似，但细菌活力很高，当风向转为陆海风时，细菌浓度脉冲增加约为平时水平的2倍。增加的原因是由于当地来源导致停滞空气中细菌的积累。这些结果表明，在本研究的海边地点，细菌浓度和活力有以下两种不同的模式：(1)与亚洲大陆来袭气旋相关的锋后长距离尘羽输送过程中，细菌浓度与粗气溶胶粒子数浓度相关，细菌活力较低；(2)在与局地源和陆海风相对应的反气旋条件下，活菌的脉冲增加。
Airborne bacteria are a major group of bioaerosols, but their temporal and spatial variations in the atmosphere are poorly understood due to a lack of accurate information at an appropriate temporal resolution. In this study, we quantified the concentration and viability of airborne bacteria at a seaside site on the southwestern coast of Japan in spring to investigate their association with synoptic weather, which was governed alternately by cyclones and anticyclones moving in the middle‐latitude westerly flow. The concentration of bacteria, on the order of 105–106 cells m−3, showed a small amplitude of variation, while the viability significantly differed in the range of 23–96% under different weather conditions. Cyclones transported bacteria from the Asian continent in their postfrontal air. Compared to bacteria under other weather conditions, the bacteria in postfrontal air had a large concentration, a low viability, and a close correlation with coarse aerosol particles. In contrast, bacterial concentration and viability in prefrontal air varied over small ranges, and no correlation between bacteria and aerosol particle number concentration was observed. During anticyclones, although bacterial concentration was similar to that in prefrontal air, bacterial viability was high, and the concentration had pulse increases of approximately 2 times the usual level when the wind changed to land/sea breezes. The increases were attributed to the accumulation of bacteria in stagnant air due to local sources. These results show the following two distinct patterns of bacterial concentration and viability at the seaside location of this study: (1) during postfrontal long‐distance dust plume transport related to a cyclone approaching from the Asian continent, the bacterial concentration is correlated with the coarse aerosol particle number concentration and the bacterial viability is low, and (2) pulse increases of viable bacteria are observed at anticyclone conditions corresponding to local sources and land‐sea breeze conditions.