Data Sheet 1_Abundance, occurrence, and degradation of airborne antibiotic resistance genes in coastal and marine atmospheres.docx

Antibiotic resistance genes (ARGs) may have significant impacts on human health and ecosystems. Airborne ARGs are reportedly widely distributed across inland cities, but little is known about their abundance in marine atmospheres. Here, we report observations of ambient ARGs during a cruise over the marginal seas of the Bohai Sea and Yellow Sea and compare them with ARGs in the coastal atmosphere. We characterized the ARGs in terms of their abundance, occurrence, degradation, and risk in the marine and coastal atmospheres. Using Na+ and Ca2+ as indicators of marine and continental aerosol sources, respectively, we quantified the mutual transport of airborne ARGs. Our results revealed that the airborne ARG abundances and the number of ARG types increased concomitantly with the mass concentrations of particulate matter because of the accumulation effect, but the ratios of ARG abundance/particulate matter concentration gradually decreased. The inconsistent trend suggested that the reduction in airborne ARGs was greater than their increase with bacterial reproduction during their accumulation and transport in the atmosphere. In addition, the number of ARG types in marine aerosols was greater than that in coastal aerosols. However, the airborne ARG abundance in marine aerosols was greater than that in clean coastal aerosols but not in polluted coastal aerosols. Some ARG types detected in marine aerosols were significantly and positively correlated with wind speed and relative humidity, implying that they may be derived from marine emissions, whereas the other ARGs are likely derived from long-range continental transport. Sea-derived airborne ARGs serve as important sources in coastal aerosols, but their contributions decrease with increasing air pollution levels. Our findings highlight the complex role of marine aerosols as both potential sources and reservoirs of airborne ARGs and highlight the critical importance of investigating the transport dynamics and variation mechanism during the long-range transport of ARGs.

抗生素抗性基因（Antibiotic resistance genes, ARGs）可对人类健康与生态系统造成显著影响。现有研究表明，空气传播的ARGs在内陆城市中广泛分布，但目前对其在海洋大气中的丰度仍知之甚少。本研究针对渤海与黄海边缘海海域的航次观测，报道了其中的环境ARGs，并将其与沿海大气中的ARGs进行对比。我们从丰度、检出情况、降解特性及风险水平四个维度，对海洋与沿海大气中的ARGs进行了表征。以钠离子（Na+）和钙离子（Ca2+）分别作为海洋气溶胶与大陆气溶胶的源示踪剂，我们定量分析了空气传播ARGs的相互传输过程。研究结果显示，由于颗粒物的累积效应，空气传播ARGs的丰度与ARGs类型数量均随颗粒物质量浓度升高而同步增加，但ARGs丰度与颗粒物浓度的比值却逐渐降低。这一不一致的变化趋势表明，在大气累积与传输过程中，空气传播ARGs的降解速率高于其随细菌繁殖实现的增殖速率。此外，海洋气溶胶中的ARGs类型数量多于沿海气溶胶。不过，海洋气溶胶中的空气传播ARGs丰度高于清洁沿海气溶胶，但在污染沿海气溶胶中则无此现象。海洋气溶胶中检出的部分ARGs类型与风速、相对湿度呈显著正相关，这暗示其可能来源于海洋排放；而其余ARGs则可能源自远距离大陆传输。海洋来源的空气传播ARGs是沿海气溶胶的重要来源，但其贡献随大气污染水平升高而逐渐降低。本研究结果凸显了海洋气溶胶作为空气传播ARGs潜在源与储存库的双重复杂作用，并强调了探究ARGs长距离传输过程中的传输动态与变异机制的关键重要性。