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Environmental Levels and Human Exposure
47
Platinum concentrations, measured or calculated, may be consid-
ered to be rough approximations of palladium concentrations. Ambient
air levels  of platinum were  predicted by applying dispersion models
including  recent  emission factors derived from engine test bench
experiments  with three-way monolith-type converters (Rosner et al.,
1998).  The  calculated  concentrations  ranged  from  4  pg/m
3
 (street
canyon, typical conditions) up to 112 pg/m
3
 (express motorway, severe
conditions). These values agree with the few measurements of
platinum air concentrations. For example, ambient air concentrations of
platinum between 8 and 106 pg/m
3
 have been reported from Munich
(Germany) in  areas  with high traffic density where platinum catalysts
are used.
Based on these sparse data, it is  impossible  to make a generali-
zation about the concentrations of palladium in air.
5.1.2
Dust
A  summary  and literature  overview of actual palladium concentra-
tions and platinum/palladium ratios in dust are given in Table 11.
Roadside dust samples  collected from broad-leaved plants in San
Diego, California  (USA) (1985) contained 15–280 µg palladium/kg, 10%
of it as dissolved forms (Hodge & Stallard, 1986). The highest values
were from highways with heavy traffic, and the lowest (15 µg/kg) were
from  plants   in  gardens  on  streets   with  light traffic. The average
platinum/palladium ratio was 2.5.
Palladium concentrations of 1–146 µg/kg  were  found in urban road
dusts in Germany in 1995. The values were strongly  correlated to the
density of traffic  and exceeded natural concentrations, which are  below
0.8 µg/kg (Schäfer et al., 1996).
The palladium concentration in US NBS primary standard coal fly
ash (SRM  1633) was  found to average 1.8 ± 0.3 µg/kg  (Shah & Wai,
1985).
5.1.3
Soil
Actual values  for palladium concentrations in soil are  summarized
in Table  11. In an area in California (USA) with high traffic  density and
unpolluted with palladium, the palladium concentration was below

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Table 11. Palladium in environmental matrices
Matrix
Date of sampling
Pd
concentratio
n (µg/kg)
Pt/Pd
ratio
Remarks
Reference
Dust
Traffic tunnel dust (Munich,
Germany)
1994
20
9.5
Helmers et al. (1998)
Traffic tunnel dust (Japan)
1987
297
mainly soot (80% carbon)
Helmers et al. (1998)
Dust near German highway 
June 1995
1–146
concentrations depend on the
density of traffic
Schäfer et al. (1996)
Urban roadside dust (Frankfurt,
Germany)
August–October
1994
5 (mean)
10
Zereini et al. (1997)
Roadside dust (heavy traffic, San
Diego, California, USA)
February/June
1985
115 (mean)
2.6
Hodge & Stallard (1986) 
Roadside dust (light traffic, San
Diego, California, USA)
July 1985
19.5 (mean)
2.5
Hodge & Stallard (1986)
Soil
Soil near Californian highway
1975
<0.7
background value
Johnson et al. (1976)
Soil near German highway
October 1990 –
March 1991
1–27 
(mean: 2)
5
0- to 4-cm layer; distance to road: 1
m
Zereini et al. (1997)
Soil near German highway
August–October
1994
1–47 
(mean: 6)
11
0- to 4-cm layer; distance to road: 1
m
Zereini et al. (1997)

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Table 11 (contd).
Matrix
Date of sampling
Pd
concentratio
n (µg/kg)
Pt/Pd
ratio
Remarks
Reference
Soil near German highway
August–October
1994
0.7
11
0- to 4-cm layer; distance to road:
10 m
Zereini et al. (1997)
Soil near German highway
June 1995
1–10
6
0- to 2-cm layer
Schäfer et al. (1996)
Sludge
Municipal sewage sludges
(Australia)
1995
18–153
samples from heavily polluted areas
Lottermoser (1995)
Muncipal sewage sludges
(Germany)
1995
260 
4700
median value
noble metal-bearing discharges 
Lottermoser (1995)
Sediment
<2 µm fraction sediments (Germany)
1984
#
4–4000
samples from a highly polluted cut-
off channel
Dissanayake et al. (1984)
Sediment near German highways
1996
0.7–19.3
0- to 2-cm layer; distance to road:
0–1 m
Cubelic et al. (1997)
Sediments from the eastern Pacific
1988
1.3–9.4
(mean: 3.2)
pelagic sediments
Goldberg et al. (1988)
Sediments from the eastern Pacific
1988
0.1–13.7
(mean: 2.9)
anoxic sediments
Goldberg et al. (1988)
For comparison: Geological background
Continental crust
0.4
1
Wedepohl (1995)

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EHC 226: Palladium
50
the detection limit (0.7 µg/kg) of the AAS technique used (Johnson et
al., 1976).
Measurements  taken in 1990 and 1991 along highway (Autobahn)
A66  Frankfurt–Wiesbaden  in  Germany  gave  a  mean  value  of  2  µg
palladium/kg  (Zereini et al., 1993). The u s e of palladium for catalytic
converters   in  automobiles   has   greatly   increased  since  1992. More
recent measurements  in 1994 of the top layer of soil along highway A67
Frankfurt–Mannheim gave a mean value of 6 µg  palladium/kg  (Zereini
et  al.,  1997).  Only   the  soil  layers down to 20 cm depth contained
measurable contents  of palladium. Levels of palladium decreased with
increasing distance from the edge of the roadway. 
To date, only  one surface soil analysis has been made in  connec-
tion with palladium production. In  1974, the palladium concentration in
the area around a mine in Sudbury, Ontario (Canada), where  PGMs are
exploited, was determined to be 2.0–4.5 µg/kg (Johnson et al., 1976).
5.1.4
Sludges
Municipal  sewage  sludges   in  southeastern   Australia   contain
palladium  concentrations  of  0.018–0.153 mg/kg dried material from
industrialized and heavily  polluted areas  (Lottermoser, 1995) (Table  11).
The palladium content in selected German sewage sludges was about
0.26  mg/kg   dry   weight.  The high palladium value (4.7 mg/kg) in a
sample of sewage sludge from Pforzheim (Germany) was due to noble
metal-bearing  discharges from the local jewellery industry
(Lottermoser, 1995). Urban sludges  receive emis s ions not only  from
traffic, but also from local industrial activities.
5.1.5
Sediments
Dissanayake et al. (1984) determined palladium concentrations in
the <2 µm fraction sediments of a highly  polluted cut-off channel of the
river Rhine near Mainz (Germany). The palladium concentrations in
12 samples collected at different sites varied over a wide range. Eight
samples   did   not  have  any  detectable   quantities   of  palladium (i.e.,
<4 µg/kg), while four samples contained 30 µg/kg, 50 µg/kg, 410 µg/kg
and the extremely high concentration of 4.0 mg/kg dry weight (Table 

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