Evaluation of patterns and spatial trends of pesticide residues data from selected areas of Tanzania by chemometric methods

This Thesis reports on the analysis of organochlorine pesticides pollution data obtained from samples collected from Vikuge farm, Coast Region, Tanzania, TPC, Moshi and southern part of lake Victoria between 1999 and 2003 by chemometric methods. Organochlorine pesticide residues data from fish samples obtained from lake Victoria were also analysed. Principal Components Analysis (PCA) of the data sets from water, soil and sediments from Vikuge has shown that the obsolete pesticides dumped at Vikuge dairy fame undergo degradation with time and the degradation pattern of the pesticides in the three environments is similar. Strong outliers were also identified in the data by the use of PCA score plots. Analysis of the data by the use of line plots has shown a decreasing trend of the concentrations of the pesticide residues with increasing distance 8om the point source (the place where obsolete pesticides were dumped). However, the data from sediment samples obtained from Vikuge fame has shown an increase of the residues concentrations with increasing distance from the source. This is attributed to the flowing water's ability to carry the residues either in solution or suspension down the hill along the drainage of the Vikuge area. Principal Components Analysis loading plots of the pollution data obtained from TPC sugarcane fields has revealed that DDT pesticides are still being used in the plantations. 'Be analysis also showed a decreasing trend of the pesticide residues concentrations with increasing distance from the sugarcane fields, which are the points of application of the pesticides. This study has also shown that in the Vikuge environment, the surface soil samples contain the highest concentration of pesticide residues whilst water is the least contaminated. PCA analysis of the pesticide residues data from fish samples showed a concentration pattern difference between the fish species, meaning that there exists bioaccumulation differences among the species. Projection to Latent Structures by means of Partial Least Squares (PLS) and Pearson correlation methods have shown that the total concentrations of DDT and its metabolites and HCH in the TPC environment an influenced by pH and temperature.