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首页> 外文期刊>Catena: An Interdisciplinary Journal of Soil Science Hydrology-Geomorphology Focusing on Geoecology and Landscape Evolution >Harmattan dust deposition and particle size in Ghana.
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Harmattan dust deposition and particle size in Ghana.

机译：加纳的Harmattan尘埃沉积和粒径。

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In Ghana, a dust-laden Harmattan wind blows from the Sahara from November to March. Some of the dust is trapped in the vegetation, in the lakes and other inland waters, while the rest is blown further away into the Ivory Coast or into the Atlantic Ocean. Several methods have been used to trap the Harmattan dust, mainly bowls with or without water, but also plates or sheets of various materials have been used. This paper compares three different methods to trap the Harmattan dust and describes the differences in amount and particle size distribution of dust trapped in various agroecological zones. The investigation shows that bowls with water trap more dust than plastic mats with 1.5 cm straw which again trap more dust than wooden plates. The bowl values can be used as a measure of the total Harmattan dust deposition, the mat values can be used as a measure of how much Harmattan dust is retained by vegetation, while the plates provide a measure of how much dust is retained on vegetation free areas. The amount of Harmattan dust captured is largest in the north, the amount of dust retained differs significantly from year to year, and a severe Harmattan in the north is not necessary coincident with severe Harmattan in the south. The dust particle size becomes finer towards the south and with increasing amounts of organic matter, and the particle size distribution shows that the major part of the dust trapped is long-term suspended material with a significant input of local dust. The dust particle size is coarser on the mats than in the bowls due to re-suspension from the mats. The presence of diatoms in the samples from Bawku indicates that a substantial part of the dust originates from former lakes in the Sahara. The amount of dust retained in the north gives a deposition rate of about 15 mm per 1000 years. This may explain why loess layers have not developed in Ghana..
机译：在加纳，11月至3月，撒哈拉沙漠上吹满了尘土的Harmattan风。一些灰尘被困在植被，湖泊和其他内陆水域中，而其他灰尘则被吹到科特迪瓦海岸或大西洋。已经采用了几种方法来捕集Harmattan的灰尘，主要是盛有或没有水的碗，但也使用了各种材料的板或片。本文比较了三种捕集哈马丹粉尘的方法，并描述了在不同农业生态区捕集的粉尘的数量和粒径分布的差异。调查显示，带水的碗比带有1.5厘米吸管的塑料垫子能收集更多的灰尘，而塑料垫子比木垫子能收集更多的灰尘。碗值可以用作衡量Harmattan灰尘总沉积量的指标，垫子值可以用作植被保留多少Harmattan灰尘的指标，而平板则可以用来衡量无植被的灰尘数量地区。北部的Harmattan灰尘捕获量最大，每年保留的灰尘量差异显着，并且北部的Harmattan严重程度与南部的Harmattan严重程度并不一定相同。随着南方和有机物含量的增加，粉尘的粒径变得越来越细，并且粒径分布表明，所捕集的粉尘的大部分是长期悬浮的物质，其中大量输入了局部粉尘。由于垫子的重新悬浮，垫子上的灰尘颗粒比碗里的要大。来自Bawku的样品中存在硅藻，这表明大部分灰尘来自撒哈拉沙漠中以前的湖泊。保留在北部的灰尘量使沉积速率约为每1000年15毫米。这可以解释为什么加纳没有形成黄土层。

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