Environmental Engineering Reference
In-Depth Information
Platinum-Group Element Distribution in
Hathersage, a Small Town Near Sheffield, UK:
Evidence for a Single Source
from Catalytic Converters
Hazel M. Prichard, Jean Sampson, and Matt J. Jackson
Introduction
More than 50% of platinum (Pt) and palladium (Pd) and more than 80% of rhodium
(Rh) is now used in the manufacture of catalytic converters fitted to vehicles
[1]
.
There have been several reviews of the accumulation of Pt, Pd and Rh in the urban
environment as a result of emissions from catalytic converters fitted to vehicle
exhaust systems
[2, 3]
. However there have been relatively few investigations of the
abundances of these precious metals in small towns. The concentrations of Pt, Pd
and Rh in road dust are thought to be dependant on traffic flow, vehicle speed
[4, 5]
and weather conditions
[6]
. These precious metals are dispersed from roads into
natural and artificial drainage
[7-10]
and have been found concentrated in sewage
and sewage ash
[11, 12]
. Within large cities it is difficult to be certain whether
platinum-group elements (PGE) in urban wastes are derived from diffuse sources
from catalytic converters fitted to vehicles, or from people with, for example,
Pd-bearing dental fillings, or point sources such as hospitals or industry
[13, 14]
.
The aim of this study was to examine the values of precious metals in the town
of Hathersage, 7 km west of the western edge of the city of Sheffield. Hathersage
lacks any industry and its inhabitants mainly work in Sheffield. It has one major
road (the A6187) traversing the centre of the town and it is situated on the north
side of the Hope Valley. It is drained by a small (2-3 m wide) stream (with minor
tributaries) that flows southwards to join the river Noe which flows from west to
east along the main valley. In this small town the study of precious metals is much
less complicated than in large cities, which can be sub-divided into residential,
commercial and industrial. The town is almost exclusively residential with a few
shops along the main road. There are no major point sources for PGE and very little
