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Sediment and nutrient deposition in Lake Volta in Ghana due to Harmattan dust

Breuning-Madsen, Henrik; Lyngsie, Gry LU and Awadzi, Theodore W. (2012) In Catena 92. p.99-105
Abstract

Harmattan is a dust-laden north-easterly wind that blows from the Sahara towards the Gulf of Guinea in the period November to March. It is the dominant wind in the north of Ghana while at the coast in the south it only occurs sporadically and here westerly or south-westerly winds dominate. Some of the dust is trapped in the vegetation, in lakes and other inland waters, and a little on the bare land. In this study, we determine the amount of sediment and nutrients that are deposited by this wind in big water bodies, exemplified by the dust deposition in the Harmattan period in the man-made Lake Volta. These depositions are compared with similar inputs by the rivers. On average, approximately 146,000. t of mineral matter and 42,000. t of... (More)

Harmattan is a dust-laden north-easterly wind that blows from the Sahara towards the Gulf of Guinea in the period November to March. It is the dominant wind in the north of Ghana while at the coast in the south it only occurs sporadically and here westerly or south-westerly winds dominate. Some of the dust is trapped in the vegetation, in lakes and other inland waters, and a little on the bare land. In this study, we determine the amount of sediment and nutrients that are deposited by this wind in big water bodies, exemplified by the dust deposition in the Harmattan period in the man-made Lake Volta. These depositions are compared with similar inputs by the rivers. On average, approximately 146,000. t of mineral matter and 42,000. t of organic matter are deposited per year in the Lake during the Harmattan periods. This is the equivalent of approximately 1% of the suspended sediment input by the rivers. The total amounts of Ca, P and Mg deposited during the Harmattan period are3000. t, 350. t and 810. t, respectively. About 40% of the Ca deposited is readily or plant available, for P and Mg it is about 50% and 20%, respectively. If the amount of readily available nutrients coming from the Harmattan dust is held against the influx of readily available (dissolved) Ca, Mg and P from the rivers to Lake Volta, it appears that the Harmattan dust accounts for only 0.7‰ Mg, 4.8‰ Ca, and 2.1% P. It must therefore be concluded that the contribution of nutrients to Lake Volta by the Harmattan dust is very limited.

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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Aeolian deposits, Eutrophication, Fluvial deposits, Lake sedimentation, West Africa
in
Catena
volume
92
pages
7 pages
publisher
Elsevier
external identifiers
  • scopus:84855185359
ISSN
0341-8162
DOI
10.1016/j.catena.2011.11.018
language
English
LU publication?
no
id
ade0bf00-c6ec-434c-8abb-73051025c018
date added to LUP
2016-10-17 14:12:31
date last changed
2017-01-01 08:37:05
@article{ade0bf00-c6ec-434c-8abb-73051025c018,
  abstract     = {<p>Harmattan is a dust-laden north-easterly wind that blows from the Sahara towards the Gulf of Guinea in the period November to March. It is the dominant wind in the north of Ghana while at the coast in the south it only occurs sporadically and here westerly or south-westerly winds dominate. Some of the dust is trapped in the vegetation, in lakes and other inland waters, and a little on the bare land. In this study, we determine the amount of sediment and nutrients that are deposited by this wind in big water bodies, exemplified by the dust deposition in the Harmattan period in the man-made Lake Volta. These depositions are compared with similar inputs by the rivers. On average, approximately 146,000. t of mineral matter and 42,000. t of organic matter are deposited per year in the Lake during the Harmattan periods. This is the equivalent of approximately 1% of the suspended sediment input by the rivers. The total amounts of Ca, P and Mg deposited during the Harmattan period are3000. t, 350. t and 810. t, respectively. About 40% of the Ca deposited is readily or plant available, for P and Mg it is about 50% and 20%, respectively. If the amount of readily available nutrients coming from the Harmattan dust is held against the influx of readily available (dissolved) Ca, Mg and P from the rivers to Lake Volta, it appears that the Harmattan dust accounts for only 0.7‰ Mg, 4.8‰ Ca, and 2.1% P. It must therefore be concluded that the contribution of nutrients to Lake Volta by the Harmattan dust is very limited.</p>},
  author       = {Breuning-Madsen, Henrik and Lyngsie, Gry and Awadzi, Theodore W.},
  issn         = {0341-8162},
  keyword      = {Aeolian deposits,Eutrophication,Fluvial deposits,Lake sedimentation,West Africa},
  language     = {eng},
  pages        = {99--105},
  publisher    = {Elsevier},
  series       = {Catena},
  title        = {Sediment and nutrient deposition in Lake Volta in Ghana due to Harmattan dust},
  url          = {http://dx.doi.org/10.1016/j.catena.2011.11.018},
  volume       = {92},
  year         = {2012},
}