Guideline Values and Metal Contamination in Soils of an Environmentally Impacted Bay

Abstract

Estimating soil guideline values for metals in environmentally impacted areas is challenging due to the contamination spreading. All Saints Bay holds the most important petrochemical complex in the southern hemisphere and an abandoned Pb smelter plant that left tons of slag rich in Pb, Cd, and Zn untreated. The aim of the study was to determine the background concentration of the metals Pb, Cr, Zn, Cu, Ni, Cd, and Co in topsoils of this environmentally impacted bay in order to establish soil guideline values and pollution indices for the monitoring of metal contamination. A total of 114 soil samples across the bay were taken from 38 samplings sites with minimal human activity. Concentrations of Pb, Cr, Zn, Cu, Ni, Cd, and Co in extracts were determined by inductively coupled plasma optical emission spectroscopy after microwave digestion. Soil guideline values, geo-accumulation, and pollution index were estimated. The natural concentration of Pb in soils was clearly influenced by smelting activities and hindered the establishment of a soil guidelines value for lead. Geo-accumulation data indicated that soils are contaminated with Pb, Co, Ni, Zn, and Cu. High pollution indices for Co, Pb, and Ni in the vicinity of the abandoned Pb plant smelter demonstrate that soils were influenced by this anthropogenic source of metals. Soils around the biggest city in the bay were also contaminated with Pb and chromium.