Spatial distribution of heavy metals in groundwater around automobile workshops in a popular Niger-Delta University town, Nigeria

Abstract

The research was carried out to assess the concentration and distribution of heavy metals in groundwater from selected automobile workshops in Ozoro metropolis, a busy university town, in the Niger Delta region of Nigeria. The major activities carried out in the sampled automobile workshops include vehicle maintenance, painting, panel beating and fabrication. Nine (9) groundwater samples from the automobile workshops and one control sample 2 km away from the influence area were analyzed. Heavy metal concentration, contamination factor, and pollution loading indices were investigated using geostatistical modeling and statistical analysis tools. Heavy metal concentrations in the various samples were determined in accordance with the Association of Official Agricultural Chemists (AOAC) International guidelines. Findings obtained from the study revealed that the groundwater was affected by leachates from the automobile workshops, as the heavy metal levels in the groundwater from the sampling sites were considerably higher than the reference point. The concentration ranges (mg/L) of the heavy metals were Cd (0.0217–0.0412), Cr (0.0643–0.0901), Cu (0.0599–0.0803), Fe (0.3118–0.4171), and Pb (0.1423–0.1781). The spatial distribution maps showed that the metals spread unevenly across the study area. The pollution indices revealed that groundwater from the sampling sites is moderately polluted with heavy metals and the trend of the pollution load index (PLI) is Cd > Ni > Cu > Mn > Pb > Zn > Fe. Comparing the results with those of international regulatory bodies, the groundwater from the study area was found to still be within the approved range for potable water. However, there is evidence of slight contamination due to the activities of the automobile workshops. This may call for minor treatment before usage, regular monitoring and ensuring that the artisans comply with relevant regulations in their operations.