Concentrations of Pb and Other Associated Elements in Soil Dust 15 Years after the Introduction of Unleaded Fuel and the Human Health Implications in Pretoria, South Africa

Abstract

Leaded fuel has been reported to contain certain amounts of toxic trace metals such as Pb and Cadmium (Cd), which may have negative impacts on humans and the environment. Unleaded fuel was introduced to South Africa in 2006 with the aim of reducing and eventually eliminating the negative impact of leaded fuel on the environment. However, trace metals are usually nonbiodegradable, and it may therefore be necessary to monitor their presence in the environment so as to evaluate their possible impact on human health. The present study evaluated the levels of Pb and other heavy metals in soil samples collected from petrol (gas) filling stations and from busy roads just around the filling stations in Pretoria, South Africa, fifteen years after the introduction of unleaded fuel. A total of twenty-four (24) soil samples were analysed for lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), arsenic (As), iron (Fe), manganese (Mn), nickel (Ni), titanium (Ti), and cadmium (Cd) using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results showed that the concentrations of the trace metals were in the following ranges: Pb, 0.08 ± 0.02–188.36 ± 15.32 ug/g; Mn, 5.35 ± 0.34–6842.43 ± 1.35 ug/g; Zn, 1.82 ± 0.22–9814.89 ± 22.32 ug/g; As, 0.21 ± 0.00–8.42 ± 2.44 ug/g; Cu, 10.51 ± 3.41–859 ± 0.09 ug/g; Cr, 5.80 ± 2.21–417.70 ± 9.08 ug/g; Ti, 19.94 ± 4.99–1036.12 ± 1.49 ug/g; and Fe, 3.06 ± 7.87–674.07 ± 12.22 mg/g. The highest concentrations from all the elements were recorded for Fe in all the collected soil samples. The concentrations of Pb in the soils collected from sites associated with high traffic and industrial areas were higher than for those from all other sites, and the differences were significant (p < 0.05). The pollution index (PI), which is the anthropogenic influence of the trace metals, and the geoaccumulation (Igeo), which allows for the removal of possible variations as regards the studied element in the soil due to the possible differences in the background value, showed that some samples were enriched anthropogenically. The PI for Ni, Pb, Cu, and Cr indicated highly anthropogenically contaminated soils, especially at sites associated with high traffic volumes and in industrial areas. The Igeo showed moderately polluted areas for Pb and Cu in high-traffic areas. The exposure routes for the toxic trace metals that were of concern in the study were either through ingestion or dermal contact. The calculated hazard quotient showed both noncarcinogenic and carcinogenic risks for Fe and Mn via ingestion and through dermal contact for both children and adults, respectively. The concentrations of Pb were high and similar to those that were previously reported in the study and pointed to vehicular emission as one of the contributors. The study also noticed an increase in the presence of Mn and Fe in all soil samples.

Preventive remediation methods minimize soil pollution

“…So far, the soil pollution status has been assessed based on the concentration of each contaminant parameter [10], [11], as well as for soil quality parameters. In real conditions, various contaminant parameters and soil quality are incalculable, especially with regard to organic contaminants [12], [13], so the assessment takes a long time and is expensive.…”

Blood lead concentrations in exposed forecourt attendants and taxi drivers in parts of South Africa

“…Lead (Pb) has been added to gasoline since the 1920s to improve combustion engine performance. The use of leaded gasoline was officially banned in South Africa in 2006 (1).…”

“…Reports have shown that vehicular emissions increase the concentration of heavy metals such as lead (Pb), arsenic (As), cadmium (Cd) and chromium (Cr) in soil and in the environment, and this has been attributed to petrol use in most cases (1). On the average between 1990 and 2013, a total of 250,000 deaths in Africa were linked to vehicular emissions (6) evoking the need for regulations.…”

Hazardous elements in road dust from petrol stations in Rzeszów (Poland) as markers of traffic-related pollution? Application of FP-XRF spectrometry as ‘white analytical technique’ for environmental assessment of hazardous elements in road dust

“…This is a significant gap in the research, as petrol stations are known to be a potential source of pollution due to the handling and storage of petroleum products. The lack of research on this topic raises concerns about the possible impact of toxic elements on the environment, the health of petrol station workers and customers, as well as the equipment used to deliver fuel (Olowoyo et al 2022). A possible scenario is the release of toxic elements into the environment through accidental spills or leaks from storage tanks or pipelines.…”