Physicochemistry of five watersheds within the oil abstraction areas of inland Niger delta, southwestern Nigeria

Abstract

Analyses of selected hydrological set of data were carried out for five watersheds around three major oil fields in the Niger Delta area to evaluate the effect of oil abstraction activities on the physicochemistry of the watersheds. The oil fields include the Afiesere oil field, Kokori oil fields, and Erimu oil fields. The study area was divided into two distinct zones namely, the oil field and non oil field areas. Each zone was analyzed for seasonal (intra-annual) variations in studied physical and chemical parameters. Result of analysis shows that concentrations of physicochemical parameters in the river waters were lower than those obtained from ponds and burrow pits/artificial lakes. Unlike the non-oil producing areas, hydrocarbon was detected, in almost every stream/river and other surface waters sampled in the oil field areas at various levels throughout the year. Mean concentrations of studied parameters show that except manganese in groundwater; manganese and zinc in river waters; Nitrate and ammonia in the soil, most of the studied parameters were highest in the oil field area. The result reported herein suggests a higher pollution status in the oil field area relative to the non oil field area.