Urban environments - Environmental Sedimentology - page 191

Street
surfaces

Gully pot

Sewers

Lakes

Fig. 6.1 Schematic diagram of the urban
sedimentary environments covered in
this chapter.

Rivers

Docks and canals

lag times, with greater opportunity for scouring,
erosion and transport of sediment. Furthermore,
the extensive presence of transport and, to a lesser
degree, industry in urban environments leads
to increased contaminant sources and enhanced
pollution pressures.
The term urban sediment is commonly used
and is used in a range of different contexts
throughout the literature. In the past urban
sediments has been a term commonly used to
refer to sediment accumulation on street surfaces,
although in this chapter the term is used in a
broader manner to mean any sediments present
within the urban environment. They, therefore,
comprise sediments accumulating on street sur-
faces, in gully pots and sewer systems, and in
receiving water bodies (rivers, canals, docks and
lakes; Figs 6.1 & 6.2).
The term road dust has also been used exten-
sively in the past, but the term dust implies fine,
respirable material (i.e. grains less than 10

will be adopted throughout this chapter. Road-
deposited sediment (RDS) can be thought of
as predominantly subaerial in nature and con-
trasts with the subaqueous (or aquatic) sediments
that are present within urban rivers, canals and
docks. Sediments accumulated within gully pots
and sewer systems are neither wholly subaerial
nor subaqueous, but experience both conditions
episodically dependent on weather conditions.
These are, therefore, described separately in this
chapter from other sediment types.

6.1.3 Historical development of urban
sedimentology

The study of urban sediments from the perspec-
tive of environmental sedimentology is a young
one. Research into urban particulates originated
out of concern for pollution and human health,
and focused on road-deposited sediment (RDS).
Early work focused on the levels of lead in RDS,
as this is a major vector for lead consumption
by children through hand-to-mouth activities.
This research documented the high levels of
lead in RDS, compared with crustal abundance
(Farmer & Lyon 1977; Duggan & Williams
1977; Harrison 1979). The importance of RDS
as a vector for Pb uptake was shown by the cor-
relation between RDS-Pb and blood-Pb levels in
children (Thornton et al. 1994). This was streng-
thened by epidemiological studies that showed a

m).
Numerous studies have shown that street sedi-
ment is composed of a full range of particle
sizes, commonly biased towards coarse material
and, therefore, the use of the term dust is not
appropriate. The terms street sediment or road
sediment have also been used in the past, but
with no formal definition. More recently the
term road-deposited sediment has been used
(e.g. Sutherland 2003). This term is favoured
here, owing to its clear descriptive nature, and

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