Levels of pesticides and metabolites emanating from a point source

This thesis reports on the levels of pesticides and metabolites emanating from a point source, an old storage site at Vikuge Farm in the Coast region Tanzania. 100 pesticides and metabolites were analyzed for in surface water, soil, sediment, and flora samples. Leaves, roots, and stems of eight plant species, were used as passive biomonitors of the spatial distribution of pesticides and metabolites from the point source. GPC cleaned extracts of the samples were analyzed by GC-ECD/NPD. Confirmatory tests were done by GC/MS and LC/MS/MS. The levels of XDDT were up to 1764.4 ng/1 in water, 18274.1 ng/g f.w. in flora samples, 533.9 ng/g d.w. in soil, and 1945.4 ng/g d.w. in sediments. The levels for £HCH were up to 1167.2 ng/1 in water, 73.7 ng/g f.w. in flora samples, 3.9 ng/g d.w. in soil, and 24.6 ng/g d.w. in sediments. The highest levels for other compounds were 29.2 ng/1 for pentachloroanisole in water, 11.1 ng/g f.w. for aldrin, and 7.7 ng/g f.w. for dieldrin in flora samples, 172 ng/1 for atrazine, 18 ng/1 for isoproturon, and 12 ng/1 for diuron in water. Trends similar to previous findings at the point source were observed. There are very strong positive correlations in the concentrations of most of the detected compounds, indicating a common source. The results indicate recent inputs of contaminants from the point source, where degradation is not significant. Mangifera indica (mango) leaves were the best bioindicators of the spatial distribution of pesticide residues, and aerial transport seemed to be the dominant route. Most concentrations of pesticides and metabolites were below the maximum residue limits (MRLs). However, some of the concentrations were higher than the respective MRLs, indicating risk and concern to public health.