Increasing use of pesticides threatens the quality of groundwater with contamination. The objective of the study was to assess the use of integrated pest management (IPM) in reducing the risks of groundwater contamination in Lake Naivasha basin, Kenya. Interviewer administered questionnaires were used to collect data on types and quantities of pesticides used; and other methods used to control weeds, pests and plant diseases. The results showed that 141 pesticides were used in the basin and that 75% of farms were applying pesticides in high quantities. All the farms were also using IPM where pesticides and other conservative means were applied. Majority of farms (62.5%) reported average harvest when IPM methods were used. It was concluded that IPM program around Lake Naivasha is still in its initial stages and in transition from intensive pesticide use. The risk of groundwater contamination in the lake basin is therefore still high.
Loss of forest cover and forest degradation are of global and national concern. Among other things, such changes can lead to reduction in stream discharges, increased erosion and loss of biodiversity, which may alter the functioning and values of affected ecosystems. This study used three Landsat images acquired in 1975, 1986 and 2005, to determine land cover changes and likely environmental impacts in Maji Mazuri forest in Kenya. The results of the analysis showed that between 1975 and 2005, natural forest decreased by about 42.31%. The likely environmental impacts include loss of biodiversity, soil erosion, and changes in forest hydrology. All stakeholders should be involved in policy formulation and implementation for better management of this important ecological resource.
Improper pesticide application has resulted in high toxicity levels causing environmental risk. The objective of the study was to determine pesticide preferences and pattern of use in farms along the shore of Lake Naivasha. Interviewer administered questionnaires and researcher observation were used to collect data on pesticides being used and pattern of use in 20 major horticultural farms around Lake Naivasha. Secondary data from journals, standards and materials safety data sheets from manufacturers were also used to determine pesticide properties such as toxicity. The results showed there were 4.3% (6) WHO class I and 14.3% (20) class II pesticides of the 141 pesticides used along the shore of Lake Naivasha. The pattern of pesticide use in the area was moderate to high and all the farms were also using Integrated Pest Management (IPM) to control pests. It was concluded that some pesticides in WHO class I that were being used along the shore of Lake Naivasha (e.g. oxamyl, methomyl and fenamiphos) are very toxic to human beings and aquatic organisms since they cause cholinesterase inhibition poisoning by inactivating the enzyme acetylcholinesterase.
Keywords: Pesticides, Environmental pollution, integrated pest management, Lake Naivasha.