MACRONUTRIENT STATUS AND PHYSICO-CHEMICAL PROPERTIES OF SOILS AROUND THE GAS FLARE SITE AT OYIGBO IN RIVERS STATE, NIGERIA

Abstract

This work assessed the impact of gas flaring on soils surrounding the gas flare stack at Oyigbo in Rivers State, Nigeria. Soil samples were collected at 10m, 50m, and 100m from the flare point and analysed for physico-chemical properties, including primary and secondary soil macronutrients, such as nitrogen, phosphorus, calcium, and magnesium. The results obtained from the investigation of the soil properties were all within the set benchmark values of EGASPIN-DPR. A One-way Analysis of Variance (ANOVA) showed that there were no significant differences (p < 0.05) in the concentration of the physico-chemical parameters and nutrients of both surface and sub-surface soils, irrespective of their distances from the flare point. For example, total organic carbon (TOC) in the soil within 10m of the gas flare point was 1.4±0.02% at surface level and 1.4±0.01% at sub-surface level. At a distance of 50m from the flare point, the total organic carbon (TOC) recorded a mean value of 1.4±0.02%, while a mean of 1.4±0.01% was recorded at a distance of 100m from the flare point. Although flare particulates could bring about acid deposition on the surrounding soils, which would decrease soil pH, the results obtained in this work showed a reverse trend of a slightly lower pH at a further 100 m distance compared to the pH range obtained 10 m away from the flare point. This trend could be attributed to anthropogenic activities, which cannot occur near the scorching temperature of the flared gas, which exceeds 1300 oC. This might have encouraged the acidification of the soils further away from the flare point.