Physicochemical Analysis and Pollution Indices for Heavy Metal Assessment in Flooded and Non-flooded Soils of Obunagha, Bayelsa State, Nigeria

Abstract

Soil samples from flood affected areas and non-affected areas of different farmlands in Obunagha, Bayelsa State, Nigeria; were collected for this study. The study was conducted to evaluate the physicochemical properties, and pollution indices of flooded and non-flooded farmlands to see if the flood had any effect in the fertility state of these soils. Atomic absorption spectroscopy (AAS) was used to identify and quantify the several heavy metals (Cd, Cr, Ni, and Zn) that were discovered in the collected soil samples. The findings indicated increased acidity since the pH of the soil varied between 4.8 and 5.7 in farmlands that were flooded and between 4.9 and 5.7 in farmlands that were not. In flooded areas, electrical conductivity ranged from 0.2x101 to 4x101 µS/cm, while in non-flooded areas, it was between 0.2x101 and 2x101 µS/cm. The cation exchange capacity in flooded farmlands was 0.16 to 0.24 meq/100 g, while in non-flooded farmlands it was 0.18 to 0.22 meq/100 g. Variations in metal contamination were found in different farming situations based on the contamination factor (CF) analysis. Chromium CF values ranged from 0.3 to 0.8 in both flooded and non-flooded farmlands, with certain non-flooded farmlands having slightly higher values. Cadmium contamination in flooded farmlands was much higher (25.5 to 43.7 CF) than in non-flooded farmlands (20.0 to 32.0 CF). Nickel contamination levels were from 0.7 to 1.1 in flooded farmlands and 0.5 to 0.8 in non-flooded farmlands, suggesting moderate pollution. Zinc contamination was consistently low throughout all circumstances, with CF values ranging from 0.2 to 0.4. According to the contamination factor average, Cd was followed by Ni, Cr, and Zn in decreasing order. The ecological pollution degree for the study area was low indicating no possible pollution by all the heavy metals. In conclusion, the study area is significantly contaminated with cadmium. Therefore, we urgently recommend monitoring the soil in the surrounding farmlands, particularly for cadmium, to prevent a potential environmental crisis.