Heavy Metal Levels and their Ecological Risks in Surface Soils at Sunyani Magazine in the Bono Region of Ghana

Abstract

The study investigated the level of seven heavy metals, arsenic (As), chromium (Cr), cop- per (Cu), manganese (Mn), lead (Pb), titanium (Ti), and zinc (Zn), in surface soils at three different sam pling points, namely, General overhauling (GO), Oil exchange (OE), and Spray- ing (SP) shop in the Sunyani magazine in the Bono region of Ghana. The ecological risks for the various metal were also measured. Generally, the metal levels were alarming as compared to the reference sample and they followed the decreasing order: Pb, Mn, Zn, Ti, Cu, Cr, As at GO shop; Mn, Pb, Cr, Ti, Zn, Cu, As, at OE shop; and Mn, Pb, Zn, Ti, Cr, Cu, As at SP shop. The contamination factor evidenced Pb as the most polluted metal and Mn as the least polluted metal in the surface soil of all sampling points in the Sunyani Maga- zine. The PLI results also suggested GO as the most polluted location followed by SP and then OE. I-geo values clearly confirm the heavy contamination of the surface soils with Pb, Zn, Cu, and As in all sampling locations, except at OE, where there was no contamination with arsenic. Practically, the surface soils at all sampling points were unpolluted (I-geo < 0) with Cr, Mn, and Ti. The potential ecological risk index (PERI) also showed a consider- able risk for surface soil at OE shop and a very high risk for GO and SP shops. Pearson product moment correlation matrix suggested a significant positive correlation (p < 0.05) among As, Cu, Pb and Zn, in the surface soils. Statistical analyses employed in various haz- ard indices such as contamination factor, pollution load, geo-accumulation, and potential ecological risks all indicate elevated levels of Pb, Zn, Cu, As, and hence contamination of the surface soil due to anthropogenic influence but background levels of Cr, Mn, and Ti, which can be attributed to geological factors.