Engineering and Technology Journal

Abstract

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.