Potential heavy metal pollution of soils from artisanal automobile workshops: the case of Suame Magazine, Ghana

Abstract

This study has investigated the levels of heavy metal pollution in the soil at a typical automobile hub where a lot of oil waste, generated through vehicular maintenance and servicing, is spilled indiscriminately into the environment. Twenty-nine (29) soil samples were taken from eight (8) locations up to a depth of 2 m (i.e., the depth to water table) in the area and analysed for the presence of Pb, Cd, Cu, Zn, Cr, Fe, Mn, and Ni. In addition, laboratory permeability and grading tests were conducted on the samples to ascertain their influence on the mobility of the heavy metals. The study results indicated that the soil in the area is well graded with coefficient of permeability in the order of 10− 3 mm/h and mostly composed of silt, sand, and gravel with little amount of clay and less than 10% organic matter content as well as a pH range of 4.04–7.74. The levels of heavy metal contamination in the soil were in the order Pb > Cd > Zn > Mn > Cu > Fe > Cr > Ni. The soil quality up to a depth of 0.6 m was found to be highly polluted with the heavy metals based on pollution load index and degree of contamination assessments. In addition, a combination of Pearson’s correlation and cluster analyses of the heavy metal associations revealed the pollution source to be anthropogenic and must, therefore, be checked due to its potential to contaminate the shallow groundwater in the area and associated health implications.