Distribution of Lead in Kerbside Soils

Abstract

Lead in emissions from motor vehicles using leaded petrol are usually monitored by analysing gas  samples. In view of the many problems associated with gas sampling, this project focussed on the  analysis of lead in kerbside samples.To this end, soil samples were collected from kerbsides and road islands within and outside the city of Durban. Thus urban, peri-urban and rural roads were included in the survey. In a preliminary study, kerb-side dust samples were collected from a vehicle-busy city street  where many pavement food vendors ply their trade. The horizontal distribution of metals as a function of distance from the kerb was  determined by analysing samples which were collected at various distances of 1–20 metres from the edge of a road. The determination of vertical distribution of  lead was achieved by taking samples at depths of 0–2 cm, 10–15 cm and 20–25 cm at each of the sampling spots.Somesub-samples were leached atpHsfound in  soils using a HazardousWaste Filtration System while parallel sub-samples from the same gross sample were acid-digested in a Microwave Digester. Analyses  were  done using ICP-AES, AAS and GF-AAS. The values for lead were found to be highest for urban sites and lowest for rural ones. Values of lead from leached   samples were found to be lower than that for digested samples whilst the values for lead over all sites was in the range 0.02–923 ppm.

KEYWORDS: Lead, soils, kerbside, distribution, analysis.