Kormos David A, Isaacman-VanWertz Gabriel, Ogejo Jactone A, Pruden Amy, Marr Linsey C
Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States.
Department of Biological Systems Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States.
ACS EST Air. 2025 Jul 18;2(8):1552-1564. doi: 10.1021/acsestair.5c00055. eCollection 2025 Aug 8.
Farms are a suspected source of dissemination of antibiotic resistance genes (ARGs) to the atmosphere, but their contribution remains poorly quantified. This study investigated the concentrations, emission rates, and particle size distributions of ARGs in air around a dairy farm and swine farm, as well as in farm wastewater and soil as potential sources, during a yearlong sampling campaign. Analysis targeted genes corresponding to a cross-section of antibiotic classes used in human and veterinary medicine, along with 16S rRNA and as indicators of total bacterial load and anthropogenic sources of ARGs, respectively. Two approaches were demonstrated for estimating emissions to account for the physical configurations of the farms. A custom sampler that collected size-resolved aerosol particles at a flow rate of 2.25 L/min only when the wind originated from the direction of interest was used to collect aerosol particles near potential sources. At the dairy and swine farms, concentrations varied significantly by sampling location, averaging 10 gene copies per cubic meter (gc m) across seasons and peaking at 10 gc m during the summer sampling period. At the swine farm, maximum concentrations reached 10 gc m for , , and near the buildings' exhaust fans. Emission rates reached ∼ 10 gc s for some ARGs, including , and 10 gc s for . ARGs were predominantly associated with coarse particles (>5 μm) near emission sources and were also present in fine (<1 μm) and accumulation (1-5 μm) mode particles near the source and at downwind locations, indicating potential for inhalation exposure and long-range transport.
农场被怀疑是抗生素抗性基因（ARGs）向大气传播的一个来源，但其贡献仍未得到充分量化。本研究在为期一年的采样活动中，调查了奶牛场和养猪场周围空气中ARGs的浓度、排放速率和粒径分布，以及作为潜在来源的农场废水和土壤中的情况。分析针对的基因对应于人类和兽医学中使用的抗生素类别的一个横截面，同时分别将16S rRNA和[此处原文缺失相关内容]作为总细菌负荷和ARGs人为来源的指标。展示了两种估算排放的方法，以考虑农场的物理布局。一种定制采样器仅在风从感兴趣的方向吹来的时候，以2.25升/分钟的流速收集粒径分辨的气溶胶颗粒，用于在潜在来源附近收集气溶胶颗粒。在奶牛场和养猪场，[此处原文缺失相关内容]浓度因采样地点而异，各季节平均为每立方米10个基因拷贝（gc/m³），在夏季采样期达到峰值10⁶ gc/m³。在养猪场，靠近建筑物排风扇处，[此处原文缺失相关内容]、[此处原文缺失相关内容]和[此处原文缺失相关内容]的最大浓度达到10⁶ gc/m³。一些ARGs的排放速率达到约10⁴ gc/s，包括[此处原文缺失相关内容]，[此处原文缺失相关内容]的排放速率为10³ gc/s。ARGs在排放源附近主要与粗颗粒（>5μm）相关，在源附近和下风向位置的细颗粒（<1μm）和积聚模式颗粒（1 - 5μm）中也有存在，表明存在吸入暴露和远距离传输的可能性。
