Browsing by Author "Mtitu, Tumaini Vincent Manfred"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Assessment of pollution in Mirongo river by rapid assessment and direct measurement methods.
    (University of Dar es Salaam, 2000) Mtitu, Tumaini Vincent Manfred
    This research was aimed at establishing the extent of pollution loading into Mirongo River using rapid assessment method and direct measurement method. Rapid assessment is a quick, easy and cheap method of estimating pollution loads into water bodies. Direct measurement method is a method of quantifying pollution load with a high degree of accuracy, however, it is expensive, and needs time and laboratory facilities. The pollution loads of selected parameters, namely, BOD, NO-3, and P034 were determined by using both methods. The rapid assessment method gave higher values than those obtained by direct measurement, when self purification effect was not considered. For example the BOD level obtained by rapid assessment method was 782 t/y without including self purification, but inclusion of self purification effect reduced the level to 349 t/yr. This level is comparable to 403 t BOD/yr, obtained by direct measurement method. The nitrates (NO-3) and phosphates (P03-4) levels obtained by rapid assessment method were 97 t/yr and 12 t/yr respectively, while by direct measurement method the levels were 78 t/yr and 2 t/yr respectively. It may be seen that the rapid assessment results for nitrates and phosphates are different from those observed by direct measurements by about 20% for NO-3 and by 80% for PO-4. This was attributed to the fact that there is no model so far which addresses the self purification possibility of the N0-3 and P03-4. It was recommended that further studies should be carried out to establish whether self purifying effect of nitrates and phosphates as the river flows downstream do exist. It was concluded that, rapid assessment method can be used to estimate pollution loads in water bodies with a reliable degree of accuracy especially in situations where direct measurement method can not be put in place because of lack of laboratory facilities. However, it is worth mentioning that the results obtained will always be the maximum values possible.