Electrothermal Atomic Absorption Spectrophotometric Determination of Vanadium, Nickel And Lead In Hydrocarbon Polluted Soils

Abstract

The present work is a part of a project on the environmental site assessment ofa local petroleum refinery to evaluate the extent of pollution of the site with focuson selected places of potential pollution. Soil samples were collected at variousdepths from almost all locations including: production units, storage tanks, thelandfill lagoons at the outside boarder of the refinery and the residence location.The analyses of vanadium, nickel and lead were carried out on extracts of the soilsamples made by five different dilute solutions of acetic acid, nitric acid, calciumchloride, EDTA. The nature of the solvent is a determining factor in the efficiencyof transport of heavy metals from the soil into the solution. All of themeasurements were conducted by graphite furnace atomic absorptionspectrophotometry.It was concluded that heavy metals are available even for the weakest extractingsolvent. This was an indication on the nature of the V, Ni and Pb, where they arein inorganic forms due to the degradation by the microorganisms of the soil andaided by dozens of raining seasons and severe hot summers of Iraq. However thesoil keeps some of the heavy metals in the original organo-metallic nature whichresulted in only partial extraction of these metals with the solutions employed.Thus, the danger from these metals is limited due to their insolubility in water.The range of vanadium detected in the various extracts is ; for nickel, the rangewas and for lead the concentration range was . The V contents were in the range of0.01 – 0.37 mg/Kg. The Ni content ranged between 0.06 and 4.5 mg/Kg. Therange of Pb contents obtained was in the range of 0.025 – 22.5 mg/Kg. The V andNi concentrations at the deep soil samples were less than that of the surfacesamples in most locations. Meanwhile, the penetration of lead contaminationseems easier than V and Ni.