TITLE:
Influence of Land Use Activities on Spatial and Temporal Variation of Nutrient Deposition in Mwanza Region: Implication to the Atmospheric Loading to the Lake Victoria
AUTHORS:
Said Ali Hamad Vuai, John D. Ibembe, Nancy W. Mungai
KEYWORDS:
Nutrient; Landuse; Lake Victoria; Precipitation; Atmospheric Pollution
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.3 No.2,
April
30,
2013
ABSTRACT: Increase in population growth and
the associated activities have increased the nutrient input to the Lake Victoria through atmosphere and river discharge.
Atmospheric input of nutrient is believed to exceed that of river discharge due
to relatively higher contribution of water mass to the Lake
from atmosphere. However, precipitation characteristics with respect to
nutrients have not been well studied to allow qualification and quantification
of atmospheric contribution to the Lake Victoria.
This study was conducted to investigate influence of land use activities on
spatial and temporal variation of nutrient inputs from atmosphere and to
estimate atmospheric loading to the Lake Victoria. The results revealed that there is significant
spatial and temporal variation of nutrient deposition in the study area. High
concentrations of
nutrients were observed during short rains starting from September to December.
This was attributed to dissolution of nutrients from soil particals and ash residues due to biomass
burning accumulated in the atmosphere during dry season of June to August.
Spatial variation of nutrients reflects land use activities. Urban and peri-urban
areas showed very high concentration of nitrate nitrogen due to industrial and
vehicle emission while rural area showed high concentration of phosphorous species and
reduced forms of nitrogen species reflecting agricultural activities and animal
keeping.
Generally, nutrient deposition load was higher in rural area compared to urban
with respective values of 15.5 and 13.9
kg·haˉ1·yˉ1 for total nitrogen and 6.1 and 2.8 kg·haˉ1·yˉ1 for total phosphorous. These results suggest
that in order to realize significant reduction of nutrient input to the Lake Victoria, measures should be taken to control agricultural
activities through proper land use planning. The measure may be directed to
reduce biomass burning, emission from industries and vehicle as well as animal
residue.