29 December 2011

Kenya: Experts to Probe Source of Lake Victoria Pollution

WATER scientists from equatorial African states have launched a four-year project at a cost of Sh700 million to find out the source of Lake Victoria pollution.

The scientist, under the banner of equatorial African deposition network, are coordinated by a University of Nairobi don, Professor Erick Odada.

He said investigation have proved that lakes in equatorial African states are highly polluted by atmospheric nutrients. Odada said atmospheric deposition in Equatorial Africa is ten times the global average and has contributed to the eutrophication of Lake Victoria and threatens Lake Malawi as well.

Preliminary estimates suggest the increased nutrient inflows are coming largely from rural areas, but although the main causes of the eutrophication are known, the rates of enrichment, its sources, and its numerous effects are not well quantified. "Since many of the farms in the area apply no fertilisers, or use very small quantities, these are not likely to be major source of the nutrients, nor will they be until fertiliser application rates reach substantially higher levels than currently seen," Odada said.

The group said by tackling the source of the pollution, the lake will be rid of pollution and restore its lost glory saying past efforts to restore the lake's freshness only dealt with arresting the situation and not tackling the source of the problem.

"The weight of the scientific evidence shows that biomass burning has increased the atmospheric loading and subsequent deposition of phosphorus and nitrogen in the lakes", said Harvey Bootsma of the University of Wisconsin.

The group called upon the governments of Equatorial African states to take appropriate action on degradation of waterways that threatens the livelihoods of 250 million Africans.

Addressing a press conference in Kisumu, Odada said it is time for these governments to stop widespread biomass burning and effect sustainable land management and improve sanitary and industrial waste treatments.

Odada says dumping of sewage wastes into the rivers and lakes due to lack of sustainable waste treatment facilities in the urban and rural centers are major contributing factors to heavy pollution of the water bodies.

According to the researchers Water quality in Lake Victoria has declined greatly in the past few decades, owing chiefly to eutrophication arising from increased inflow of nutrients into the lake.

According to their survey funded by global environment facility and United Nations University, Nutrient inputs and concentrations of phosphorus have risen ten times in the deeper lake waters.

This they argue has stimulated the increase algae growth that is highly deoxygenating the water, increased sickness for humans and animals drawing water from the lake, clogging of water intake filters, and increased chemical treatment costs for urban centres.

This they said has reduced the number of important fish species like Tilapia and the famous Nile perch introduced in the lake five decades ago. "Apart from the near-total loss of the deep water species, the deoxygenating of the lake's bottom waters now poses a constant threat, even to fish in shallower portions of the lake, as periodic upwelling of hypoxic water causes massive fish kills", said Trent university professor Peter Dillon. "The increased nutrient loads have also spurred the water hyacinth infestations", he added.

The nutrients represent a transfer of materials at an increasing rate from the terrestrial basin to the lake. "Among others, these transfers comprise organic and inorganic suspended solids and dissolved nutrients carried by streams, terrestrial dust from wind erosion, inorganic compounds in the smoke produced by combustion either in cooking fires or forest burning, and direct additions along the lake shores of human and animal waste associated with domestic water use", he added.

However the reports exonerate activities within the lake over the menace posting that nutrients released from soil particles washed or blown off the land surface by erosion, from burning wood-fuels, and from human and animal waste from areas surrounding the lake are to be blamed.

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