Li Daoming, Cui Shijie, Wu Yun, Wang Junfeng, Ge Xinlei
Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CIC-AEET), School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Toxics. 2024 Feb 20;12(3):164. doi: 10.3390/toxics12030164.
Aerosol liquid water content (ALWC) affects the mass loading, optical properties, and toxicity of aerosols. However, the measurement of ALWC is very rare due to its requirement of sophisticated instruments and its high operational costs. In this work, we improved on our previous simple, low-cost method by using a combination of one real-time fine particulate matter (PM) monitor and two turbidimeters and successfully applied these for the direct measurement of ALWC in PM in Nanjing during the summer of 2023. The average ALWC during this measurement period occupied 1/6 of the total PM mass, and this contribution was even greater with the elevation in the PM concentration. The ALWC was, as anticipated, closely related to the relative humidity (RH) and PM concentrations, but it did not always increase with the air quality index (AQI) due to the fact that polluted periods in summer were often governed by high O levels, not PM levels. The ALWC also had a great impact on visibility; it could decrease the visibility rapidly to hazy conditions when the dry PM was not high (30 μg m) or the AQI was "good" (75~100), indicating that the air quality classified as "good" using the dry PM concentration might actually be "lightly polluted" if the ALWC is included. We also found that the air mass originating from Northeast China had the lowest PM mass concentration yet the highest ALWC values due to its high RH. Moreover, the quantification of ALWC levels can help us understand the solubility/bioavailability and thus the toxic effects of some specific components (for example, heavy metals or organics). Moreover, the influence of ALWC on air quality classifications should also be considered in the assessment of the health effects of air pollution and in public health early warning and protection.
气溶胶液态水含量（ALWC）会影响气溶胶的质量负荷、光学特性和毒性。然而，由于测量ALWC需要精密仪器且运营成本高昂，因此相关测量非常少见。在这项研究中，我们改进了之前简单、低成本的方法，采用一台实时细颗粒物（PM）监测仪和两台浊度仪相结合的方式，并于2023年夏季在南京成功将其用于直接测量PM中的ALWC。在此测量期间，ALWC的平均值约占总PM质量的1/6，且随着PM浓度升高，这一贡献更大。正如预期的那样，ALWC与相对湿度（RH）和PM浓度密切相关，但由于夏季污染期往往受高臭氧水平而非PM水平主导，所以它并不总是随空气质量指数（AQI）增加。ALWC对能见度也有很大影响；当干燥PM不高（约30μg/m³）或AQI为“良好”（75 - 100）时，它会迅速将能见度降低至朦胧状态，这表明如果将ALWC考虑在内，仅依据干燥PM浓度判定为“良好”的空气质量实际上可能为“轻度污染”。我们还发现，源自中国东北的气团PM质量浓度最低，但由于其相对湿度高，ALWC值最高。此外，对ALWC水平的量化有助于我们了解某些特定成分（例如重金属或有机物）的溶解度/生物利用度，进而了解其毒性效应。此外，在评估空气污染对健康的影响以及公共卫生预警与防护中，也应考虑ALWC对空气质量分类的影响。
