Abstract:
Consumption of vegetables that are cultivated on the polluted soil and irrigated with the
polluted river water is the concern of many residents here in Addis. Low-income group of
the community are using the polluted river water for keeping their livelihood by growing
vegetables and then marketing. The suitability of the Little Akaki River Water for
irrigation has been assessed by this thesis work. Water quality tests of the samples
taken from the diverted river water for irrigation, the soil and plant tissue testes for their
heavy metal contents have been tested. The farming sites selected for the study were
Gofa and kaliti areas. The vegetables for which the tests conducted were Carrot, Swiss
chard Red beet and Lettuce.
The study revealed that the bacteriological and helminths pollution of The Little Akaki
River is grossly very high. The chemical and physical pollution level of the river is in an
alarming stage; as a result, the river water is not fit for any classified use. In addition, the
salinity effects of the irrigation waters on the soil are slight to moderate but have no
infiltration effect. With regard to the toxicity to sensitive crops taking the sodium
concentration as an indicator, the water is not suitable in the degree range of restriction
from slightly to moderate for sprinkler irrigation, but have no problem for surface
irrigation. The irrigation waters are also unfit to irrigate susceptible crops with the degree
of restriction on use as sever.
The heavy metals content in the irrigation water reveals that manganese has exceeded
the limit; Cobalt shall be further investigated since the result found is < 0.1 mg/l and the
limit set is 0.05mg/l. All the other selected and tested elements are below the maximum
limit. The soil test results reveal that all the selected elements are below the maximum
limit set except Nickel. Only zinc and chromium exceeded the maximum limits (table 16)
that should be adsorbed and present in the consumable plant tissues