Publications

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.

Use of microwaves as an alternate heat source to replace conventional heating has been studied in organic synthesis. Microwave irradiation results in faster reaction rates, cleaner production, thereby reducing energy consumption. This also leads to better environmental impacts and is considered green chemistry. This Paper reviews application of microwave irradiation in transesterification reactions for production of biodiesels. Transesterification of Croton Megalocarpus oil using homogeneous sodium hydroxide catalyst was carried out using conventional heating in a water bath, and in a microwave oven. Synthesis of fatty acid methyl ester (FAME) was studied for the reaction variables catalyst concentration, methanol to oil molar feed ratio and reaction time. Results indicated that reaction time was reduced to about 2% for a similar yield when microwave irradiation was employed instead of convective heating. During convectional heating, a FAME yield of 96% corresponded to a methanol-to-oil molar ratio of 6:1, catalyst of 1 %, temperature of 70oC, and reaction time of 60 minute. During microwave irradiation, a yield of 92% was obtained when methanol-to-oil molar ratio was 9:1, catalyst concentration 0.5 %, and reaction time 1 minute. FAME was analyzed through gas chromatography.

Groundwater contamination by pesticides is an
environmental health concern throughout the world. Many
pesticides do not leach because they are adsorbed on the
soil particles or organic matter even though they may have
a relatively high solubility. The objective of this study was
to determine the relationship between soil permeability
and organic carbon in the transport of pesticides into
groundwater along the shore of Lake Naivasha, using
regression analysis of soil permeability and organic carbon
data collected along the shore. The results showed that the
soil organic carbon (foc) positively affected the soil
permeability (k) and were related by the equation k=
80.724(1.726)foc. It was concluded that organic carbon
increased soil permeability by 30%, thereby recharging the
aquifer while at the same time reducing pesticide transport
into groundwater. Based on these findings the study
recommended that the use of compost (organic
amendments) should be increased in place of inorganic
fertilizers.