The Atmospheric Deposition of Phosphorus in Lake Victoria (East Africa)
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Date
2005
Journal Title
Journal ISSN
Volume Title
Publisher
Springer Link
Abstract
Wet and dry atmospheric fluxes of total phosphorus (TP) and soluble reactive phosphorus
(SRP) measured at four sites over a 12-month period were used to estimate lake-wide
atmospheric phosphorus (P) deposition to Lake Victoria, East Africa. Atmospheric samples were
collected in plastic buckets with top diameter of 25.5 cm by 30 cm deep. The highest P loading rates
of 2.7 (TP) and 0.8 (SRP) kg ha 2 year 1 were measured at Mwanza compared to less than 1.9
(TP) and 0.65 (SRP) kg ha 2 year 1 measured in other three sites. By applying these loading rates
to the lake surface, it was estimated that 13.5 ktons (13.5 · 103 kg) of TP were deposited annually
into the lake from the atmosphere. Thirty-two percent of the total was found to be in the SRP form.
Dryfall, a component ignored in previous studies exceeded wet deposition by contributing 75% of
the total P input. However, materials deposited by dryfall made a lesser contribution to soluble
form of phosphorus, as SRP concentrations in the wet samples were 2–3 times higher than SRP
concentrations in dry samples. The annual fluxes of phosphorus measured on the south and western
shores of Lake Victoria (1.8–2.7 kg ha 2 year 1
) are near the upper range of similar fluxes measured
in the tropics. In comparison with the existing estimates of municipal and runoff P inputs
from other studies, it is estimated that atmospheric deposition represent 55% of the total phosphorus
input to the Lake Victoria. The four sampling sites were fairly clustered and wet and dry P
deposition data were collected from shore/land stations and applied to open lake areas to estimate
lake-wide P deposition. In this regard, the estimates determined here should be viewed as a first
order approximation of actual P load deposited into the lake.
Description
Keywords
Atmospheric deposition, Dry deposition, Lake Victoria, Phosphorus, Watershed, Wet deposition
Citation
Tamatamah, R.A., Hecky, R.E. and Duthie, H., 2005. The atmospheric deposition of phosphorus in Lake Victoria (East Africa). Biogeochemistry, 73(2), pp.325-344.