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Evaluating and monitoring environmental exposure to micro-pollutants. Pesticides Pollution - Case study of the lake Naivasha Basin

Student:Yasser Abbasi
Timeline:October 2014 - 14 November 2018

In spite of the pollution caused by pesticides, it is still one of important methods for protecting agriculture and horticultural products against pests. However, the use of pesticides continues to cause anxiety about the effects of pesticides on the environment and on human health. Therefore, awareness of micro-pollutants (the residues of pesticides) distribution and their fates can help to understand the hazards of chemical pollutants in soil, water, crops and biota. During application of pesticide from its source to agricultural area, some of it may be adsorbed into sediments, organic matter, soil particles, biota and crops. Therefore, to recognize the distribution of pesticides in environment, it is necessary to evaluate any relevant factors and variation of pesticides fates in the environment.

This study is about the pollution of pesticides in Naivasha basin (Kenya) in which a dens agricultural activity has caused a worry about the micro-pollutants contamination in environment. Although the pollution of different agro-chemicals ( e.g. pesticides and fertilizers) has been explored in many studies, a comprehensive evaluation of environmental exposure to micro-contaminants residues coming from pesticide application by using new techniques and models in the Naivasha basin remains necessary. The scientific challenge of this study is to find the exposure risk to micro-pollutants, source of pollution and fate of pollutants by using partitioning approach. To meet this challenge, the following objectives are defined: 1) studying micro-pollutants distribution and risk assessment in the Naivasha basin by using a partitioning approach. The main theory of this objective is that applied pesticides can be washed from riparian areas and transferred to the rivers and the Lake. It means that the pollution of agricultural areas affects the quality of rivers in the basin and finally make a pollution for the Lake as the main receiving water body of the study area. In this objective it is going to identify how any of the environmental compartments is exposed to the pesticides residues. 2)  Application of passive sampling techniques for studying and measuring the micro-pollutants in aquatic environments of Naivasha basin. The main challenge of this objective is the spatial and temporal application of passive sampling for achieving enough time series data about pesticides concentration in the rivers and the lake of Naivasha. 3) simulation of micro-pollutants transportation and their fates in the Naivasha basin under weather effects and different land use/cover. The main aim of this objective is exploring the transfer of pesticides through different streams/rivers in Naivasha basin to the Lake by using model approach.

In this study field surveys, laboratory, in-situ experiments and models are employed to determine the exposure risk of different environmental compartment to micro pollutants (e.g. pesticides residues). It is predicted that the results of this study can answer the questions about screening of chemicals (use) and exposure risk, pollution of surface water resources and fate of pesticides.

Indicative sampling points of the Lake, streams and the rivers Malewa and Gilgil and Karati

diagram for partitioning of the pollutant in environment (Seth and Mackay 2001)

Schematic diagram of diffusion and permeation samplers (Górecki & Namieśnik 2002)

Meet the team

Y. Abbasi (Yasser)
Graduate Student
dr.ir. C.M.M. Mannaerts (Chris)
Promotor
Research theme
Water Cycle and Climate

Water, food and energy security and environmental safety are key challenges to our societies. “Information on water quantity and quality and their variation is urgently needed for national policies and management strategies, as well as for UN conventions on climate and sustainable development, and the achievement of the Millennium Goals”.

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