Spatio‑temporal variations in physicochemical water quality parameters of Lake Bunyonyi, Southwestern Uganda
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
SN Applied Sciences
Abstract
The current study was carried out to examine the spatial and temporal variations of physicochemical water quality
parameters of Lake Bunyonyi. The observations were made on the surface water of Lake Bunyonyi for 1 year to determine
the water quality. The basic 12 variables used to determine the quality of water were measured monthly at nine
stations. Water temperature, dissolved oxygen (DO), turbidity, electric conductivity (EC), pH and Secchi depth (SD) were
measured in the field, while parameters like total nitrogen (TN), total phosphorus (TP), nitrite-nitrogen (
NO2-N), nitratenitrogen
(
NO3-N), soluble reactive phosphorus (SRP) were determined following APHA 2017 standard guidelines for
physicochemical analysis. Taking into account standard guidelines for drinking water by the Uganda National Bureau
of Standards (UNBS) and the World Health Organization (WHO), the water quality index (WQI) was used to determine
the water quality. Temperature, DO, pH, turbidity and EC did not differ significantly among the study stations (p > 0.05)
but showed significant temporal variations among the study months (p < 0.05). Likewise, TN, TP, NO2-
N, NO3-
N and SRP
did not differ significantly among the study stations (p > 0.05) but showed significant temporal variations among the
study months (p < 0.05). The WQI values ranged from 28.36 to 49 across and from 28.2 to 56.2 between study months
with an overall mean value of 36.9. The measured water quality variables did not exceed the UNBS and WHO standards
for drinking water in all months and at all stations. According to these values, the water quality of Lake Bunyonyi generally
belongs to the ‘good’ class in terms of drinking water quality based on the WQI classification. The study findings are
fundamentally important for policy makers in setting guidelines for effective lake management.
Description
Keywords
Spatio-temporal variability · Water quality · Water quality index · Lake Bunyonyi