There are limited economic and reliable tools to monitor the effects of airborne particulate matter PM originating from rapid industrialization, urbanization, population growth, and economic development. It is now well established that urban PM contains magnetic particles along with other air pollutants. The velocity and temporal variability of the deposition of such PM on tree leaves are subject to the pollution sources, climate, and local atmospheric conditions. Therefore, these variables have to be taken into account during a biomonitoring. This study presents a magnetic biomonitoring in the city of Querétaro. In the city’s metropolitan area, the most abundant and perennial tree species for biomonitoring is Ficus benjamina. For leaves of this species, the number of days needed for collection NDNC was measured, taking into account the meteorological conditions and the time at which they reached the saturation of airborne PM (pollutants). By means of sequential sampling, we identified that the minimum NDNC after a rainfall > 3 mm is 15 days. In such a period, total suspended particle TSP depositions reach its dynamic equilibrium. This behavior can be observed from measurements of specific magnetic susceptibility χ in Ficus benjamina samples and their comparison with TSP depositions collected with traditional Hi-Vol monitoring systems. After the NDNC calculation, a magnetic monitoring was performed with the biomonitor Ficus benjamina to evaluate the air quality at different sites in the metropolitan area every month for a period of 5 months. Values of χ ranged from 0.45 to 18.52 × 10⁻⁸m³kg⁻¹. The species Ficus benjamina can be used as a biomonitor in the city of Querétaro only in seasons (winter-spring) with no or low rainfall. The species has the advantage of providing current PM information about a specific period of time.

中文翻译：

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利用墨西哥克雷塔罗州榕树的叶子对大气尘埃进行磁性生物监测。

监测源自快速工业化，城市化，人口增长和经济发展的空气中颗粒物PM影响的经济和可靠工具有限。现已公认，城市PM包含磁性颗粒以及其他空气污染物。此类PM在树叶上的沉积速度和时间变化取决于污染源，气候和当地大气条件。因此，在生物监测期间必须考虑这些变量。这项研究提出了克雷塔罗市的磁性生物监测。在城市大都市地区，用于生物监测的最丰富和多年生的树种是榕树（Ficus benjamina）。对于该物种的叶片，测量了收集NDNC所需的天数，同时考虑了气象条件和达到空气中PM（污染物）饱和的时间。通过顺序采样，我们确定降雨> 3 mm后的最小NDNC为15天。在此期间，总悬浮粒子TSP沉积达到其动态平衡。这种行为可以通过测量榕树样品中的特定磁化率χ并将其与传统Hi-Vol监测系统收集的TSP沉积物进行比较来观察到。NDNC计算后，用生物监测器榕榕（Ficus benjamina）进行了磁监测每月评估大城市不同地点的空气质量，为期5个月。χ的值在0.45至18.52×10 ^-8 m ³ kg ^{-1的范围内}。该种垂叶榕可以用作城市克雷塔罗只在季节（冬春），没有或低降雨一个生物监测。该物种的优势在于可以提供有关特定时间段的当前PM信息。