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A comparative study of the nutrient status of two reservoirs in southeast Ghana
Author(s) -
AnsaAsare O. D.,
Asante Kwadwo Ansong
Publication year - 1998
Publication title -
lakes and reservoirs: research and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.296
H-Index - 39
eISSN - 1440-1770
pISSN - 1320-5331
DOI - 10.1046/j.1440-1770.1998.00074.x
Subject(s) - wet season , nutrient , seasonality , dry season , environmental science , fertilizer , hydrology (agriculture) , nitrate , agronomy , biology , ecology , geology , geotechnical engineering
The nutrient status of Weija and Kpong reservoirs, southeast Ghana, was assessed by determining seasonal indices and interannual changes. The nutrient levels were found to be higher in Weija Reservoir. However, ammonia did not follow that pattern. Seasonal distribution of nutrients also showed higher levels in Weija than in Kpong. Seasonal variation showed higher levels of nitrates in the rainy season at Weija than at Kpong; however, data from Kpong Reservoir involved considerable experimental error. The monthly trend of nitrates showed a unique pattern in the months of March and May, the main ploughing periods for farming in the Weija catchment area when most fertilizer is applied. In general, over a 5‐year period, there were no trends in nutrient levels. However, for sulfates there was a gradual decrease in spatial distribution from 1993 to 1997. The seasonal distribution for sulfate increased slightly. Seasonal trends as well as a seasonal index were determined and in all cases Weija showed higher levels than Kpong derived from land‐based fertilizers on the reservoir. On average, there was a higher seasonal index in the rainy season than in the dry season. However, the phosphate index in January at both Weija and Kpong was high. The seasonal index for both Weija and Kpong was high in the rainy season and low in the dry season. However, the phosphate index in January at both Weija and Kpong was high. The high nitrate index in March was due to rain in the latter part of that month. Ammonia–nitrogen in November also showed high levels; November was just after the rainy season so some influence from rain persisted.