Heavy metals and metalloids content and enrichment in Gulf Coast sediments in the vicinity of an oil refinery

Abstract

The heavy metals and metalloids released by the oil refineries accumulated in the natural lakes may severely endanger the aquatic life. For this purpose the present study was carried out to explore the potential risk posed by the heavy metals and metalloids in the drainage ditch of a large oil refinery located at the southwest of Lake Pontchartrain, Norco, St. Charles Parish, Louisiana, USA. The concentration and enrichment of 24 heavy metals and metalloids (Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Ti, V, and Zn) were determined in sediments at a distance of 5km from an oil refinery to the Lake Pontchartrain. The results showed that the concentration of 24 metals and metalloids declined gradually with the distance from the refinery to the lake, suggesting the oil refinery as a potential source. The enrichment factors (EFs) for Cd, Sb, V, As, and Se indicated that they were heavily accumulated in the sediments but were insignificant for Zn, Be, Ni, Pb, Co, Cu, and Cr. The results of EDTA and BCR extraction demonstrated that Zn, Cd, Co, Cu, Ni, Be and Pb were the most bioavailable elements in the sediments and would cause potential hazards to the environment. Based on our results, the oil refinery can be presumed as one of the sources responsible for the trace metal pollution of Lake Pontchartrain.