Contamination Levels of Organochlorine and Organophosphorous Pesticide Residues in Water and Sediment from River Owena, Nigeria

River Owena functions as the source of water for the Owena dam which supplies drinking water to the communities in the region, the river also plays an important economic role in irrigation and fish farming in the region. But there has been an indiscriminate used of pesticide because residents of the study area are not well orientated concerning the negative impact of pesticide in the environment. Analysis of organochlorine and organophosphorous pesticide residues was carried out in water and sediment from river Owena, the objective of the research is to determine the contamination levels of organochlorine and organophosphorous pesticide in the water and sediment of river Owena. Analysis was carried out using gas chromatography coupled with electron capture detector in order to identify and quantify the concentration of organochlorine and organophosphorous pesticide in the water and sediment samples from river Owena. Analysis revealed the contamination of water and sediment with organophosphorous pesticide residues at different contamination levels in both dry and rainy season, while a low levels of organochlorine pesticide residues only during the dry season. The TOPP for sediment samples ranges from 1.045mg/L during the dry season and 2.279mg/L during the rainy season, while the TOPP for water samples ranges from 7.163mg/L during the dry season to 7.83mg/L during the rainy season. The TOCP values ranges from 1.288mg/L to 0.015mg/L for sediment and water samples respectively during the dry season, while organochlorine pesticides were not detected during the rainy season. The occurrence and seasonal variation of organophosphorous pesticide residues in river Owena can be attributed to the intense agricultural and urban activities in the vicinity of river Owena.