降尘收集方法对降尘效率的影响

大气降尘收集方法较多,但目前还没有通用的野外观测方法,由于降尘收集方法的多样性以及降尘缸收集效率的不同,所观测的结果很难进行对比.目前对各类降尘缸收集降尘效率的研究较少.在腾格里沙漠地区,利用国家标准规定降尘缸,对干法、湿法、过滤网法、过滤网+玻璃球法和减速沿法这5种降尘收集方法进行对比研究,旨在探讨不同降尘收集方法的收集效率,为准确评价区域降尘量提供依据.干法收集的降尘量仅占湿法的5%～62%;减速法仅占湿法的50%～95%;过滤网法仅占湿法的43%～89%;玻璃球+过滤网法仅占湿法的40%～80%.不同的降尘收集方法,风速明显影响降尘效率,平均风速<2.5m·s-1时,降尘效率随平均风速增加而降低;但在平均风速>2.5 m·s-1时,降尘效率与平均风速之间无明显规律.湿法收集的降尘粒度最细,依次为减速法、玻璃球+过滤网法、过滤网法和干法.平均风速,>5 m·s-1的平均风速与湿法,减速法收集的降尘量之间可以用指数函数表示.不同降尘方法观测的数据可以相互转化,干法、过滤网、过滤网+玻璃球法、减速沿法与湿法收集的降尘量之间为线性相关.在干旱及半干旱地区,减速法能够作为一种替代湿法进行收集降尘的有效方法.

Effect of Dust Deposition Collection Methods on Collection Efficiency

There are lots of dust deposition collection methods on dust deposition, but there is no standard field observation method. At present, researchers have studied dust deposition using different methods in this issue, but due to the different observation method and collection efficiency, the research results are incomparable. The efficiency of the standard dust deposition gauge including dry, wet, net, net and glass ball and slowing speed methods was studied in the Tengger Desert. The amount of the dry method collected material was only about 5% to 62% of the wet method, the net method was only about 43% to 89% of the wet method, the net and glass ball method was only about 40% to 80% of the wet method. Wind speed obviously affected the dust deposition efficiency in all observation methods, the dust deposition efficiency decreased with increasing wind speed when the wind speed was smaller than 2.5 m·s^-1, but the dust deposition efficiency had no clear trend with wind speed when the wind speed was larger than 2.5 m·s^-1. The particle size of collected material by wet method was the smallest, followed by the slowing speed method, the net and glass ball method, the wet method and the dry method. There are relationships between the averaged wind speed, the averaged larger than 5 m·s^-1 wind speed and the amount of dust deposition collected by the wet and the slowing speed methods, which can be expressed as exponential function. There are also linear relationships between the amount of collected material by the wet and dry, net, net and glass ball and slowing speed methods. The wet method is the best dust deposition collecting method, followed by the slow wind speed method. Therefore, in the arid and semi-arid regions, the slowing wind speed method can be used to replace the wet method to collect dust deposition.