Electrothermal atomic absorption spectrophotometric determination of vanadium, nickel and lead in hydrocarbon polluted soils

الملخص EN

The present work is a part of a project on the environmental site assessment of a local petroleum refinery to evaluate the extent of pollution of the site with focus on selected places of potential pollution.

Soil samples were collected at various depths from almost all locations including : production units, storage tanks, the landfill 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 soil samples made by five different dilute solutions of acetic acid, nitric acid, calcium chloride, EDTA.

The nature of the solvent is a determining factor in the efficiency of transport of heavy metals from the soil into the solution.

All of the measurements were conducted by graphite furnace atomic absorption spectrophotometry.

It was concluded that heavy metals are available even for the weakest extracting solvent.

This was an indication on the nature of the V, Ni and Pb, where they are in inorganic forms due to the degradation by the microorganisms of the soil and aided by dozens of raining seasons and severe hot summers of Iraq.

However the soil keeps some of the heavy metals in the original organo-metallic nature which resulted 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 range was and for lead the concentration range was.

The V contents were in the range of 0.01-0.37 mg / Kg.

The Ni content ranged between 0.06 and 4.5 mg / Kg.

The range of Pb contents obtained was in the range of 0.025 – 22.5 mg / Kg.

The V and Ni concentrations at the deep soil samples were less than that of the surface samples in most locations.

Meanwhile, the penetration of lead contamination seems easier than V and Ni.