A Comparative Assessment of Heavy Metal Pollution in Soil using pH Enrichment Factor and Pollution Index

Abstract

Many researchers have described pH as heavy metals pollution indicator in soil, but no effort has been made to determine level or quantity of heavy metals that could be indicated by pH. This study measured in-situ soil pH values at Nekede motor mechanic village against the natural background values. We used readings obtained to compute pH enrichment factor (pHeF) at several measurement points. Pollution index (Pi) data from previous work in the same mechanic village serve as a comparative statistical tool. Result shows that pHeF have strong relationship with Pi, with correlation coefficient (r): 0.8. While Pi range was 1.6-2.1, with a mean value of 1.8, pHeF range was 1.7-2.0 with same mean value of 1.8. This revelation suggests that in heavy metal contaminated topsoil, pHeF tends to Pi. A pHeF of 1 implies a Pi of 1, which indicates zero pollution. In this case, the soil condition for pHeF and Pi is neutral. pHeF < 1 = Alkalinity and Pi < 1 = No pollution. pHeF > 1 = Acidity and toxicity of soil at threshold ≤ 5.515, while Pi > 1 = pollution. pHeF shows degree of heavy metal contamination in soil for urgent decision making, where Pi that depends on sophisticated stereoscopic analysis may not be available. Future studies shall consider food security around mechanic villages.