Departament de Física, Universitat Politècnica de Catalunya (UPC), Barcelona, Spain.
Departament de Física, Universitat Politècnica de Catalunya (UPC), Barcelona, Spain.
Sci Total Environ. 2022 Apr 20;818:151827. doi: 10.1016/j.scitotenv.2021.151827. Epub 2021 Nov 20.
Betula (birch) pollen is one of the most important causes of respiratory allergy in Northern and Central Europe. While birch trees are abundant in Central, Northern, and Eastern Europe, they are scarce in the Mediterranean territories, especially in the Iberian Peninsula (IP), where they grow only in the northern regions and as ornamental trees in urban areas. However, the airborne birch pollen patterns in Catalonia (Northeastern IP) show abrupt high concentrations in areas with usually low local influence. The intensity of the derived health problems can be increased by outbreaks due to long-range pollen transport. The present work evaluates the different potential contributions to Catalonia from the main source regions: Pyrenees, Cantabria, and the forests of France and Central Europe. To this end, we computed the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) back trajectories of air masses associated with the main Betula pollen peaks occurring simultaneously over different Catalan monitoring stations, and we studied their provenance over a 15-year period. The Vielha aerobiological station on the northern slopes of the Central Pyrenees was used to identify the dates of the pollen season in the Pyrenean region. In order to better understand the role of the Pyrenees, which is the nearest of the four birch forested regions, we classified the pollen peaks in the other Catalan stations into three groups based on the relationship between the peak and the pollen season in the Pyrenees. Our analysis of back-trajectory residence time, combined with the associated pollen concentration, reveals that two principal routes other than the Pyrenean forest sustain the northerly fluxes that enter Catalonia and carry significant concentrations of Betula pollen. This study has also allowed quantifying the differentiated contributions of the potential source regions. In addition, the Weather Research Forecast (WRF) mesoscale model has been used to study three specific episodes. Both models, HYSPLIT and WRF, complement each other and have allowed for better understanding of the main mechanisms governing the entry of birch pollen to the region.
桦树花粉是北欧和中欧地区最重要的呼吸道过敏原因之一。虽然桦树在中欧、北欧和东欧较为丰富，但在地中海地区却很少见，特别是在伊比利亚半岛（IP），那里只有在北部地区和城市地区作为观赏树木生长。然而，加泰罗尼亚（IP 东北部）的空气中桦树花粉模式显示，在通常本地影响较低的地区突然出现高浓度。由于长距离花粉传输引起的爆发，由此产生的健康问题的强度可能会增加。本研究评估了来自主要源区（比利牛斯山脉、坎塔布里亚和法国及中欧的森林）对加泰罗尼亚的不同潜在贡献。为此，我们计算了与同时发生在不同加泰罗尼亚监测站的主要桦树花粉高峰相关的混合单粒子拉格朗日综合轨迹（HYSPLIT）空气团的后轨迹，并在 15 年期间研究了它们的来源。比利牛斯山脉中部北坡的 Vielha 气传生物学站被用来确定比利牛斯地区花粉季节的日期。为了更好地理解作为四个桦树森林地区中最近的比利牛斯山脉的作用，我们根据其他加泰罗尼亚站的花粉高峰与比利牛斯山脉花粉季节之间的关系，将花粉高峰分为三组。我们对后轨迹停留时间的分析，结合相关的花粉浓度，表明除了比利牛斯山脉森林之外，还有另外两个主要的路径可以维持进入加泰罗尼亚的北流，并携带大量的桦树花粉。本研究还允许量化潜在源区的差异化贡献。此外，还使用天气研究预测（WRF）中尺度模型研究了三个特定的事件。HYSPLIT 和 WRF 这两个模型相互补充，使我们更好地理解了控制桦树花粉进入该地区的主要机制。
