dc.description.abstract |
Lake Tana water resource is of crucial importance serving multiple purposes and having largest
surface area with fresh water body in Ethiopia. However, Lake Tana is facing water quality
problem due to pollution caused by anthropogenic influences. This study was undertaken to
assess water quality of the Southern gulf of Lake Tana using indicator microorganisms and some
physicochemical parameters. A total of 48 water samples were collected from water of Southern
gulf of Lake Tana. In this study, sites were selected purposely and sampling was taken seasonally
dividing into wet and dry seasons. Indicator microorganisms (total and fecal coliforms) and some
physicochemical parameters such as pH, Temperature, EC, TDS, Turbidity, NO
3
, DO
and BOD5 were determined to estimate pollution status in different sites. In the present study,
total coliforms and fecal coliforms were enumerated using a multiple tube fermentation technique
with MacConkey broth as the presumptive medium, eosine methylene blue (EMB) agar as the
confirmatory medium. In this study counts of fecal coliforms were 1 MPN/100ml to 1600
MPN/100ml with lowest and highest mean value of 1MPN/100 ml at S8 to 1076.5±3.1
MPN/100ml at S4 with significant p<0.05 and total coliforms counts were also ranges 1
MPN/100ml to 1600 MPN/100ml with mean value of 4.8±1.81 MPN/100ml at SR6 to 1600
MPN/100ml at S4 and SR8 with significant p<0.05. Most of high count of total and fecal
coliforms in this study was recorded during wet season. Physicochemical parameters of this study
showed that some of parameters were under the group that made the lake was not polluted, but
some parameters where in the group that informs the lake was deteriorated. Although there was
significant variation in most of the physicochemical parameters on season and sites, some of the
physicochemical parameters were insignificant to sites and revealed some contamination both dry
and wet seasons. Generally, southern gulf of Lake Tana water also showed that some of the
parameters were within the limits of USEPA and EEPA some were exceeded the limits which
depict occurrence of pollution. Therefore, undertaking constructive management action and
giving attention is needed for this anthropogenic interference which causing Southern gulf of
Lake Tana water was polluted.
Key word: Bacteria, Lake Tana, pollution, physicochemical,
,
PO
4,
NH
4 |
en_US |