Bacteria in the global atmosphere - Part 2: Modeling of emissions and transport between different ecosystems
Bacteria in the global atmosphere - Part 2: Modeling of emissions and transport between different ecosystems
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DOI：
10.5194/acp-9-9281-2009
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发表时间：
2009-01-01
影响因子：
6.3
通讯作者：
Lawrence, M. G.
中科院分区：
文献类型：
--
作者：
Burrows, S. M.;Butler, T.;Lawrence, M. G.
细菌不断地在大气中传播，这可能对人类健康、农业、云的形成和细菌物种的扩散产生影响。我们模拟细菌的全球运输，在一般循环模型中用直径为1 μ m和3 μ m的球形固体颗粒示踪剂表示。我们研究了影响颗粒停留时间和分布的因素，包括排放区域、云凝结核活性和冰相沉淀去除。全球分布在很大程度上取决于对云滴和冰的吸收的假设。在较小程度上，输运也受排放区域、颗粒物直径和季节的影响。我们发现大气停留时间的季节变化本身不足以解释观测到的空气可培养颗粒细菌浓度的季节变化，表明这种变化主要是由可培养性和/或排放强度的季节变化驱动的。我们研究了生态系统之间细菌交换的潜力，并通过使用最大似然估计技术获得了每个生态系统通量的粗略估计，以及在同伴论文中描述的现有观测结果的新汇编。在全球范围内，我们估计含细菌颗粒向大气的总排放量为7.6x10(23)-3.5x10(24) a(-1)，主要来自草原、灌木和农作物。根据颗粒中细菌细胞的质量分数，我们估计发射的细菌-的质量为40-1800 Gg a（-1）。为了增进对这一问题的理解，有必要对空气中的细菌含量和细菌的表面与大气交换率进行更多的测量。未来对湿地、热沙漠、冻土带、偏远冰川和沿海地区以及海洋的观测将特别有趣。
Bacteria are constantly being transported through the atmosphere, which may have implications for human health, agriculture, cloud formation, and the dispersal of bacterial species. We simulate the global transport of bacteria, represented as 1 mu m and 3 mu m diameter spherical solid particle tracers in a general circulation model. We investigate factors influencing residence time and distribution of the particles, including emission region, cloud condensation nucleus activity and removal by ice-phase precipitation. The global distribution depends strongly on the assumptions made about uptake into cloud droplets and ice. The transport is also affected, to a lesser extent, by the emission region, particulate diameter, and season. We find that the seasonal variation in atmospheric residence time is insufficient to explain by itself the observed seasonal variation in concentrations of particulate airborne culturable bacteria, indicating that this variability is mainly driven by seasonal variations in culturability and/or emission strength. We examine the potential for exchange of bacteria between ecosystems and obtain rough estimates of the flux from each ecosystem by using a maximum likelihood estimation technique, together with a new compilation of available observations described in a companion paper. Globally, we estimate the total emissions of bacteria-containing particles to the atmosphere to be 7.6x10(23)-3.5x10(24) a(-1), originating mainly from grasslands, shrubs and crops. We estimate the mass of emitted bacteria- to be 40-1800 Gg a(-1), depending on the mass fraction of bacterial cells in the particles. In order to improve understanding of this topic, more measurements of the bacterial content of the air and of the rate of surface-atmosphere exchange of bacteria will be necessary. Future observations in wetlands, hot deserts, tundra, remote glacial and coastal regions and over oceans will be of particular interest.