Aims: To determine the levels of heavy metals in fall-out dust from Rehoboth town, Hardap region,
Namibia.
Study Design: Modified open bucket samplers were used to collect the settleable particulate. Six
“ordinary” open buckets were placed at different locations (Blocks A to F). In Rehoboth town. Each
bucket’s contents were filtered using a Buchner funnel connected to the diaphragm vacuum pump.
The residues collected after the filtering were dried and transferred into clean, pre-labelled
polyethylene bags and then transported to Analytical Laboratory Services, Windhoek Namibia, for
further processing and analyses. Place and Duration of Study: Rehoboth town, Hardap region, Namibia, between September 2015
and December 2015.
Methodology: The samples were digested according to EPA method 3050B for Inductively Coupled
Plasma-Optical Emission Spectrophotometer (ICP-OES) analysis. Ten (10) mL of each digestate
was taken and mixed with equal volume of matrix modifier and then analysed using ICP-OES (ICP:
Perkin Elmer Optima 7000 DV) for the levels of chromium, cadmium, lead, arsenic, manganese,
zinc and nickel.
Results: The levels of heavy metals obtained showed the metals’ enrichment of the dust fall ranging
between 0.05 – 1.38 Block A; 0.06-37.44 Block B; 0.05-3.43 Block C; 0.05-4.68 Block D; 0.09-1.73
Block E and 0.09-1.56 Block F respectively. This showed very high enrichment for Block B and
deficient to minimal, moderate enrichment for Blocks A, C, D, E and F. The results of contamination
factors indicated moderate, considerate and highly contaminated dust fall with the heavy metals;
which are related to common and input from anthropogenically induced sources.
Conclusion: Human activities in the town of Rehoboth, Namibia have obviously increased the
levels of heavy metals in dust fall-out. The calculation of pollution load index (PLI) clearly points to
deterioration of site quality. This obviously is a grave concern following environmental accumulation
and non-biodegradation of heavy metal and hence, the need to have all major roads and inter
linking street roads to be paved to mitigate the release of dust into the atmosphere.