Evaluating the Contamination Degree and Risk Assessment of Heavy Metals Around Active Dumpsite Environment: A Case Study of Ozoro Community, Delta State, Nigeria

Abstract

The use of lowlands for refuse collection point (dumpsite) is a very common practice in Nigeria. However, people cultivated the areas within the vicinity of the dumpsites, without knowledge of the risk of these heavy metals. Therefore, this study was done to evaluate the risk of heavy metals pollution of soils within the vicinity of an active dumpsite. Four (4) soil samples (from 4 locations) at a depth of 0–20 cm were collected from the vicinity of the dumpsite. The heavy metals (e.g. iron lead, nickel and cadmium) concentration of the collected soil samples were analyzed according to American Society for Testing and Materials (ASTM) International methods. Pollution indices (contamination factor, enrichment factor, pollution load index and geoaccumulation index) were used to ascertain the level of heavy metals contamination of the dumpsite area. Results obtained from the soil tests revealed that, the dumpsite area had high heavy metals concentrations. The heavy metals concentrations were of this ranged: iron 3420 mg kg-1 to 4323 mg kg-1, lead 28.92 mg kg-1 to 58.84 mg kg-1, nickel 2.89 mg kg-1 to 6.91 mg kg-1, and cadmium from 1.04 mg kg-1 to 2.05 mg kg-1. The heavy metals concentrations ranked as Fe > Pb > Ni > Cd. Pollution indices results showed that cadmium had the highest contamination factor, enrichment factor, pollution load index and geoaccumulation index values, which portrayed that the dumpsite soil was heavily contaminated with cadmium. Results of the correlation showed a strong correlation (r = 0.87) between iron and nickel, indicating that the two heavy metals got their pollution from the source(s). Results obtained from this study will further help the government and environmental regulators to plan and carried out suitable remediation strategies, to clean the environment.