Automotive trace metal concentrations on the South African national road (N3) and its impact on the environment.

Abstract

The environment is currently experiencing the negative effects of globalisation and unsustainable development with environmentally harmful activities increasing at an alarming rate in South Africa and other developing countries. This is due to these countries circumventing the implementation of environmental policies against foreign investors, such as vehicle manufacturers and chemical industries, to allow for a reduction in fiscal austerity by increasing the gross domestic product. The effects of these activities have a greater impact on the environment and population of developing nations than developed ones. Heavy metal contamination is one of the major concerns related to vehicle manufacturers and toxic chemical industries in terms of environmental management. The aim of this research was to assess the impact of vehicle pollution along the South African National Road (N3) between Durban and Hilton as it is one of the major transportation routes from the harbour. The elemental concentrations in the leaves of Bidens pilosa, that are picked and cooked by communities that live along the roadside, were investigated. The concentrations of thirteen elements were selectively investigated to determine the impact of soil quality on elemental uptake by vegetation and to assess for potential metal toxicities. Soil was evaluated for metal pollution by calculation of geo-accumulation indices and enrichment factors. Common sources of contamination were identified by principal component analysis and spatial distribution of toxic elements; lead and cadmium was developed via geographic information system (GIS). The study showed Bidens pilosa to contain high concentrations of toxic metals especially that of lead, which were linked to high soil concentrations. Soil quality indicators showed soils to be moderately to heavily contaminated in some areas and moderately contaminated in others. Enrichment results showed moderate to significantly enriched soils. Statistical analyses indicated different sources for the toxic metals (cadmium and lead) and the Kriging interpolation study depicted and demonstrated the spatial diffusion of both cadmium and lead concentrations throughout the study area of the N3. The road transport sector is a key source for heavy metal contamination as it is the preferred method of transport by most industries in South Africa and other developing countries. This study therefore provides insight into the impacts of vehicle pollution in the surrounding environment.