Assessment of the in-situ concentrations of some heavy metals in surface soil dusts at the Katima Mulilo urban waste dumpsite, Namibia

Type Journal Article - International Journal of Advanced Scientific and Technical Research
Title Assessment of the in-situ concentrations of some heavy metals in surface soil dusts at the Katima Mulilo urban waste dumpsite, Namibia
Author(s)
Volume 4
Issue 5
Publication (Day/Month/Year) 2015
Page numbers 88-100
URL http://rspublication.com/ijst/2015/AUG15/7.pdf
Abstract
The growing dominance of urban environment with heavy metals through natural and
anthropogenic depositions and the potentially adverse health implications following
environmental contaminations have focused attention on the disposal of urban and industrial
wastes. This study employed analytical procedures to investigate the in-situ concentrations of
lead, chromium, cadmium, arsenic, cobalt, nickel, selenium, copper, zinc, manganese, vanadium
and uranium in the surface soil dusts at the Katima Mulilo urban waste dumpsite. Replicate
surface soil dusts samples were randomly collected from twelve different points within the waste
dumpsite, properly homogenized and three sub-samples were digested by EPA method 3050B.
Then, the digestates were analyzed for the levels of the heavy metals using Inductively Coupled
Plasma-Optical Emission Spectrophotometer (ICP: Perkin Elmer Optima 7000 DV). The results
obtained varied widely with manganese recording the highest mean concentration of 73.23
mg/kg while selenium recorded the lowest level (0.27 mg/kg). The present concentrations of the
heavy metals were generally lower than their respective guideline values for the protection of
human and environmental health. Based on established guidelines for the contamination
categories of heavy metals, the pollution indexes of the heavy metals generally revealed low
contamination of the surface soil dusts but this does not preclude consideration for future effects
due to accumulation and non-biodradability of heavy metals in environment. The results of soil
enrichment factors however revealed significant to high enrichment (19.23 – 20.25) of the
surface soil dusts by the heavy metals. These suggest that some of the waste materials disposed
at the dumpsite may be rich sources of the heavy metals which upon decomposition released the
elements onto the receiving surface soil. Therefore, we recommend that further research be
carried out on the heavy metals concentration of the waste materials to identify those that are
potential sources of soil contamination and suggest appropriate treatment and disposal methods.
Furthermore, the urban wastes management department must provide machinery for wastes
segregation prior to disposal and incineration.

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