Quantifying toxic contaminants in four major dump sites of Thabo Mofutsanyane district, Eastern Free State
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Date
2015-11
Authors
Lamula, Sphamandla Qhubekani Njabuliso
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State (Qwaqwa Campus)
Abstract
The large number of cases of groundwater pollution at landfills and the substantial resources
spent on remediation suggests that landfill leachate is a significant source of pollutants,
especially when considering different kinds o f contaminants in landfill leachates. The longterm
effect of the geological barrier beneath municipal-waste landfills is a critical issue for
soil and groundwater protection. Soil to plant transfer of trace metals is the major pathway of
human exposure to metal contaminations. Therefore, the present study was conducted to
determine trace meta l levels such as arsenic (As), cadmium (Cd), chromium (Cr), copper
(Cu), manganese (Mn), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), cobalt (Co) and
zinc (Zn) in soil and plant samples collected from four major dumpsites in Thabo
Mofutsanyane District, Eastern Free State in South Africa. Samples (soil and plants) were
collected from Harrismith, Qwaqwa and Bethlehem from two different landfills. Soil samples
were collected at a depth of 0-15 cm from each part and pooled to form a composite sample.
Plant samples were pulled from the soil together with their roots using an ager. Four acid
digest techniques (HCl, HN03, HCl04 and HF) were used and inductively coupled plasma
optical emission spectrometry (ICP-OES) determined the concentrations of heavy meta ls.
During the four seasons (spring, summer, autumn and winter), the concentration of Zn was
higher in summer with value o f 3076.56± 12.02 compared to winter 1733.5 1 ±39.33. The
concentration of Pb was within the threshold except in Qwaqwa and Bethlehem site A with
values of 3 15.79±30.26 and 230.82±35.24. Cd concentration fluctuates during the seasons but
the highest value of 6. 15±0.06 was recorded during winter. The level of Mn in all dumpsites
was very unstable and above the standard permissible limit. The common plants identified in
the dumpsites are Cosmos species, Eragrostis plana, Elusine indica, and were all found to
contain high level of heavy metals. Principal Correlation Analysis (PCA) analysis showed
that Qwaqwa and Harrismith had the highest load of heavy metals and the dendrogram
confirmed the similarity in metal distributions in the dumpsites. This study highlights
environmental implications of heavy and trace metals in all dumpsites studied. There was no
significant difference in the concentration of metals within and outside the dumpsites which
confirms metals can be distributed above I0 m range. All the trace metals analysed in this
study had higher concentrations above the permitted limits set by USEPA and WHO. This
study revealed the levels and impacts of heavy metal concentrations on the dumpsites, as well
as the risks they may pose to near or far surroundings and its attendant health implications.
Description
Keywords
Groundwater -- Pollution -- South Africa -- Free State, Refuse and refuse disposal, Plants -- Effect of heavy metals -- South Africa -- Free State, Soils -- Heavy metal content -- South Africa -- Free State, Dissertation (M.Sc. Botany (Plant Sciences))--University of the Free State (Qwaqwa Campus), 2015