Risk identifi cation of Hg and Pb in soil: a case study from Pangkep Regency, Indonesia

Lithogenic and anthropogenic activities can increase the concentration of heavy metals in the soil and degradation of environmental quality. Pangkajene dan kepulauan (Pangkep) regency is one of the areas in South Sulawesi Province which has severe environmental pressure. Twenty two surface soils of Pangkajene dan Kepulauan (Pangkep) regency, South Sulawesi, Indonesia were col- lected in order to determine the contamination status and potential ecological risks. The geo-accu- mulation index (Igeo) and potential ecological risk index (RI) were used to evaluate the contamina- tion and risk level. The metal content in soils was determined using cold vapor atomic absorption spectrophotometer (CV-AAS) for Hg and fl ame atomic absorption spectrophotometer (F-AAS) for Pb. The results showed that the concentration of Hg and Pb ranged from 20.81- 223.47 mg kg-1 and 25.98- 108.68 mg kg-1 respectively. Pb concentration in studied soil was below the quality standard for soil, whereas the Hg concentration was exceeded the soil quality standard. Agriculture fi eld in Bungoro sub-district has the highest Hg concentration. The Igeo value showed that the soil in Pangkajene was extremely enriched with Hg and moderately enriched by Pb. The ecological risk index showed com- prehensively the watershed area was at extreme risk level in need of effective monitoring and pol- lution control, and Hg is the important risk factor of Pangkajene watershed area.