Bubble-mediated transport and aerosolization of microorganisms: implications for natural and manual aeration to adjacent communities

通过机械系统或通过风/波浪作用的曝气（将气泡引入水中）代表了氧气溶解到水体中的常见方式。这些过程对于防止形成“死区”是很重要的，“死区”是指氧气浓度太低而无法维持动物生命的区域。由于气泡比水轻，它们自然会浮到水面。像沉积物、微生物、毒素和有机物这样的小颗粒，以及气体，在气泡行进到表面时，可以随气泡一起沿着。当气泡在表面破裂时，细菌和其他颗粒和气体可以通过空气扩散，增加人类接触的机会。虽然我们了解气泡将颗粒雾化到空气中的力量，但对其根本原因却知之甚少。该项目的目标是了解环境条件，如气泡大小，微生物细胞大小和水化学如何影响微生物的运输和气溶胶的产生。通过在岩溪（Pasadena，MD，USA）进行受控实验室实验和现场研究来实现这一目标，岩溪是一个低氧水体，具有机械曝气系统以防止死区形成。 本研究基于气泡和微生物细胞大小以及水化学参数的变化可以用来预测微生物气溶胶化的假设。公众将通过公民科学项目参与这项研究，提高国家的科学素养。这项研究的成功完成有可能通过预防和控制病原体和毒素的气溶胶化来保护人类和生态健康。微生物生活在充满空气-水界面的环境中，例如在湖面、充气产生的气泡周围或土壤中的水囊中发现的微生物。微生物在这些多相界面的行为在很大程度上是研究不足，尽管它们在控制空气-水-土壤传质的重要性。这项研究的目标是解决这些知识差距，以了解气泡大小，微生物细胞大小和水盐度如何影响气泡介导的微生物运输和雾化。该研究的指导假设是，环境变量（气泡大小，微生物大小，盐度）的变化将导致运输和气溶胶化的差异，可以从先前推导出的模型胶体的方程和关系进行预测。这些预测将在多个尺度上进行测试，在受控的实验室条件下使用不同的微生物，从病毒到真核藻类，以测量界面和小规模的运输。将在低氧水生环境（岩溪，帕萨迪纳，MD）的机械曝气过程中测量现场规模的运输。相互作用和气泡介导的运输和雾化将采用最先进的颗粒跟踪方法、流式细胞术、定量聚合酶链反应和微生物群落表征进行定量。高中，本科和研究生的多元化群体将接受跨学科研究课题的培训，公众将通过一些推广活动参与研究。这些实验将产生可量化的关系，可用于了解气泡生成过程如何影响水柱中的微生物扩散和气溶胶，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的评估来支持。影响审查标准。

Aeration (the introduction of air bubbles into water) either through mechanical systems or through wind/wave action represents a common way for oxygen to become dissolved into water bodies. Such processes are important to prevent the formation of “dead-zones”, areas where the oxygen concentration is too low to support animal life. Because bubbles are lighter than water, they naturally rise to the surface. Small particles like sediment, microbes, toxins, and organic matter, as well as gases can be swept along with the bubble as it travels to the surface. When the bubble bursts at the surface, bacteria and other particles and gases can disperse through the air, increasing the chances of human exposure. While we understand the power of bubbles to aerosolize particles into the air, the underlying causes are poorly understood. The goal of this project is to understand how environmental conditions such as bubble size, microbial cell size, and water chemistry affects microbial transport and aerosol generation. This goal will be achieved using both controlled laboratory experiments and field study at Rock Creek (Pasadena, MD, USA), a low oxygen water body that has a mechanical aeration system to prevent dead zone formation. This research is based on the hypothesis that changes in bubble and microbial cell size, as well as water chemistry parameters can be used to predict microbial aerosolization. The public will be engaged in this research through citizen science projects, increasing the scientific literacy of the Nation. Successful completion of this research has potential to protect human and ecological health through prevention and control of pathogens and toxin aerosolization. Microorganisms live in an environment filled with air-water interfaces, such as those found at the surface of a lake, around gas bubbles from aeration, or in water pockets trapped in soils. The behavior of microorganisms at these multiphase interfaces is largely understudied, in spite of their importance in controlling air-water-soil mass transfer. The goal of this research is to address these gaps in knowledge to understand how bubble size, microbial cell size, and water salinity affects bubble-mediated microbial transport and aerosolization. The research is guided by the hypothesis that changes in environmental variables (bubble size, microbe size, salinity) will result in differences in transport and aerosolization that can be predicted from equations and relationship previously derived for model colloids. These predictions will be tested across multiple scales using diverse microorganisms ranging in size from viruses to eukaryotic algae under controlled laboratory conditions to measure interfacial and small-scale transport. Field-scale transport will be measured during mechanical aeration of a low-oxygen aquatic environment (Rock Creek, Pasadena, MD). Interactions and bubble-mediated transport and aerosolization will be quantified with state-of-the-art particle tracking methods, flow cytometry, quantitative polymerase chain reaction, and microbial community characterization. A diverse group of high school, undergraduate, and graduate students will be trained in inter-disciplinary research topics and the public will be engaged in the research through a number of outreach activities. These experiments will result in quantifiable relationships that can be used to understand how bubble-generating processes will impact microbial dispersal within the water column and into aerosols, which can be applied to microbial ecology or microbial risk assessment for novel or worsening microbial threats.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.