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Pergamon Environmat imnational, Vol. 23,No. 1, pp. 91-101.1997 copyright 01997 Fhvicx Science Ltd F’rintcd in the USA. All rights resewed
0160-4120/97 Sl7.00+.00
PIIS016Q4120(96)00080-3
CONTAMINATION OF ROADSIDE SOIL AND GRASS WITH HEAVY METALS
A.A. Olajire and E.T. Ayodele Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
EI 9604-139 M (Received 22 April 1996; accepted I5 November 1996)
The concentrations of heavy metals were determined in roadside soil and grass from different locations in Ibadan metropolis and two highways. The levels found (in pg g’) were: Cr - 20.6-104; Mn - 86.2-355; Fe - 1737-4455; Ni - 10.9-115; Cu - 8.94-80.5; Zn - 43.5-213; Cd - 0.18-2.70; and Pb - 205-730. There was no significant difference (P < 0.10) between the mean concentrations of these metals in the high and low traffic density areas suggesting that sources other than the motorcar also influence the levels of these metals in roadside soil and grass. c~pvrigh~ 01997 Elsevier science ,!,td
INTRODUCTION
The levels of lead in roadside dust, soil, and grass have been extensively studied (Day et al. 1975; Olsen and Skogerboe 1975; Harrison 1979; Biggins and Harrison 1980; Farmer and Lyon 1977; Duggan and Williams 1977; Solomon and Hartford 1976; Day 1977; Motto et al. 1970; Lacasse 1970; Schuck 1970; Chow 1970; Archer and Barratt 1976), but less has been done on the concentrations of other metals (Ward et al. 1977; Harrison et al. 198 1; Fergusson et al. 1980; Hopke et al. 1980; Fergusson and Simonds 1983). In all their studies, the levels of lead were high in the mg g’ range. Lead has also been reported to be the metal with the greatest enrichment over background levels (Paciga and Jervis 1976), making it impossible to compare the concentration of lead from one place to another unless the environment, sampling, and analytical method are comparable.
The variations in the levels of lead in roadside soil and vegetation are frequently attributed to traffic density (Archer and Barratt 1976; van Hassel et al. 1979; Fergusson et al. 1980). However, in Hong Kong (Ho 1979), the lead levels did not correlate with traffic volume. The levels of nickel and zinc (van Hassel et al. 1979) were also reported to correlate with traffic
density. This contamination of roadside soil and vege- tation is considered to arise mainly from motor vehicle exhaust such as lead from tetraethyl lead compounds in petrol (LargeMrerff and Specht 1970; Day 1977; Ward et al. 1977; Bourcier and Hindin 1979; Fergusson et al. 1980; Hopke et al. 1980; Fergusson 1990). Lead, cadmium, zinc, selenium, antimony, and arsenic come from fossil fuel combustion and motor vehicle tire wear (Steinnes 1990; Hopke et al. 1980; Ward et al. 1977). Arsenic is produced during copper smelters (O’Neill 1990), cadmium in primary non-ferrous metal pro- duction (Pacyna 1987), and chromium from plated steel (Lazrus et al. 1970; Ward et al. 1977). However, this aspect of contamination of roadside soil and grass with heavy metals, especially cadmium and mercury which are among the priority pollutants as established by the United Kingdom, Department of the Environment (DOE 1988) has not been much investigated in Nigeria. Thus, an attempt is made in this study to investigate the level of heavy metals contamination of roadside soil and grass of Ibadan metropolis, the largest city in Africa, and two highways linking Ibadan. It appears no such determination has previously been reported in Ibadan and its environs.
91
92 A.A. Olajire and E.T. Ayodele
NRL : Nigerion Breweries Limited Ibodm
. WABL : West Africa Bottcry Limited
~~0.3 ; Eroodcahq h-perotion of Oyo State
“.t :univerrity of lbodon Main Gate
AP 1 African Petroleum (Petrol filtinq Station)
F.S : Fruit Sellers
OSF 1 ‘&lily Slondord food
Fig. 1. Map showing the sampling locations.
MATERIALS AND METHODS
Sampling
The sampling sites selected in Ibadan metropolis are shown in Fig. 1. In addition, two highways, Ibadan- Ilorin (rl, r,, r,, r,, and rs) and Ibadan-Iwo (w,, w,, w,, wq, and w5), roads which represented the heavily and less travelled roads, respectively, were studied. Forty- two samples (28 soil and 14 grass samples) were collected per week from October 1995 to November 1995 inclusive. The sampling points are designated as S(soi1) and G(grass) with subscripts h, 1, m, b, and v, representing high traffic, low traffic, roadside me- chanics, battery smelter, and tire vulcanizer, respective- ly. Soil samples were also collected at a site (rJ as a function of distance from highways (2 m, 10 m, 15 m, 25 m, and 35 m). A homegrown grass and a garden soil collected from university staff residential area (R), remote from traffic and activities of roadside workers, served as an uncontaminated reference point. Samples
were collected, using plastic bag containers, from the gutter and roadside, and transported to the laboratory. They were dried at 60°C overnight. Approximately 10 g subsamples of these materials were pulverized to uni- form size.
Analysis
About 0.5 g pulverized samples, accurately weighed, were placed in a 250 cm3 round-bottomed quick-fit Pyrex flask and a 50 cm3 mixture of hot concentrated nitric (800 mL/L) and perchloric (200 mL/L) acids was added. The flask was then connected to a 50-cm tall Vigreux column which was connected to a 25-cm tall Liebig condenser unit. The entire assembly was mounted on an electric heating plate. The samples were digested until clear solutions were obtained (approxi- mately 6 h). The solutions were cooled and filtered through acid-washed Whatman No. 1 filter papers and then made up to a volume of 100 cm3 using doubly distilled water.
Heavy metal contamination of roadside soil and grass 93
A reagent blank was prepared using a 50 cm3 mixture of nitric and perchloric acids in a 250 cm3 round-bot- tomed quick-fit Pyrex flask, and the entire sequence of steps was followed as described for the sample pre- paration. The samples were analyzed by atomic ab- sorption spectrophotometry using Chem Tech Analyti- cal alpha 4 model operated per the instrument’s ma- nual. The instrument was calibrated using mixed cali- bration. Standard solutions were prepared by stepwise dilution of stock certified standard solutions of heavy metals. Results were corrected for reagent blanks and non-atomic absorption. The reproducibility of the method of digestion was checked by carrying out a duplicate analysis. Duplicate results did not differ by more than 5% of the mean.
RESULTS AND DISCUSSION
The 24 sampling sites including the two highways are shown in Fig. 1. The analytical results given in Tables 1, 4, 5, and 6 are the means (and standard de- viations) for 5 to 6 samples taken from each site at weekly intervals, October-November 1995. It is sur- prising that for the small sampling area in this work, a wide range of concentrations occurred for some of the metals analyzed. At any one sampling point, the range was greater than the variability in the analytical pro- cedure. The seasonal variations could be due to local weather which can significantly influence the levels of trace metals in roadside soil. This applies particularly to rain, where metal species in solution or in suspen- sion are removed in street runoff (Bourcier and Hindin 1979; Fergusson et al. 1980; Revitt and Ellis 1980).
Table 1 gives the results of the chemical analysis of roadside soil for the two series of heavy and low traffic areas. The mean levels of the metals analyzed in the soil samples from the heavily travelled road (high traf- fic area) were compared with those of the less traveled road (low traffic area) using the “Student - t” test (Table 2). The metals were not significantly different (P<O. 10) in the two areas.
To deduce the possible sources of the metal con- taminants, one approach taken was to determine the correlation coefficients between elements. As seen in Table 3, the correlation between element pairs in the sample taken from high traffic density and low traffic density areas is poor. The low correlation coefficient found between metal pairs considered in both groups suggests that sources other than the motorcar also in- fluence the levels of these metals in the roadside soil at these areas and suggests a non-common source of the
metals with varying contributions at different sampling sites. In addition to motor traffic, other probable sources of these metals in soil and grass samples are roadside deposition of the residues of motor oil, battery wastes, and car tires, a common practice of our road- side mechanics, battery smelters, and tire vulcanizers.
Higher concentrations of the elements were obtained in samples taken from other roadsides of Ibadan metropolis (Table 4) than the ones on the highways (Table I), except at site w3, where the concentrations of lead and antimony were quite high. This is an indi- cation of an enhanced level of surface contamination caused by roadside workers and Hawkers, in addition to contamination caused by traffic density. The high level of lead and antimony in the soil and grass samples collected at site w, is not surprising, as the site is near the factory of West African Battery Limited, the pro- ducer of Exide Battery. No detectable traces of seleni- um were found in the soil and grass samples collected at all the sampling sites.
The variation in metal contents of roadside soil with distance from highway was demonstrated by the analysis of soil samples collected at various distances from site r, in Ogbomoso, and the results are given in Table 5. The data in Table 5 were statistically assessed with regression analysis. The regression of the metal content of soil on the distance from the highway is shown in Fig. 2. The concentration gradients with distance follow the order: Fe > Mn > Pb > Zn > Cu > Ni > Cr > Cd. The concentrations of Fe, Pb, Cd, and Zn with negative regression coefficients decrease in road- side soil with increasing distance from the road, indi- cating their relation to traffic. The concentrations of Cu, Ni, Cr, and Mn, with positive regression coef- ficients, increase in roadside soil with increasing dis- tance from the highway, indicating the independence of roadside Cu, Ni, Cr, and Mn on traffic.
The roadside distribution of Pb is traditionally ascribed to combustion of leaded gasoline by auto- mobiles. The observations in this study, coupled with the fact that Cd is present as impurity in some of the common Zn-containing additives, e.g., the antioxidant Zn-dithiophosphate in lubricating motor oil and the presence of Cd associated with the use of technical Zn- oxide and Zn-diethyl or dimethyl carbamate in vulcani- zation (Largerwerff and Specht 1970), show that Cd and Zn in soil originate from motor vehicle emissions and from motor vehicle tire wear. Iron could originate from the discarded galvanized iron roofs of the houses used as shops in the side streets.
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P’61 61LZ
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(C’SI)
(LZEI) 9’LS
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Heavy metal contamination of roadside soil and grass 95
Table 2. Statistical” assessment of heavy metal contents of roadside soil from two areas of different traffk density.
Area
High traffic density (5 samples) Means (ug g-‘) R.S.D. (%)
Low traffic density (5 samples) Means (pg g-r) R.S.D. (%)
Cr Mn Fe Ni cu Zn Cd Pb
51.6 196 2613 38.9 31.4 86.1 1.36 307 15.7 59.2 41.2 30.8 46.5 35.9 31.8 19.5
39.0 131 2234 28.0 20.3 92.6 0.91 356 34.4 25.3 12.7 30.5 37.7 16.4 39.6 24.7
t-values 1.61 1.04 0.76 1.50 1.34 -0.38 1.60 -0.93 ’ Critical value of Id for 8 d.f is 1.86 at 90% confidence level. d.f is degree of freedom. R.S.D is relative standard deviation.
Table 3. Correlation coefficients between elements in roadside soil.
Element pairs
Pb-Cr Pb-Zn Pb-Cu Pb - Fe Pb-Ni Pd-Cd Cr-Fe Cr-Zn Cd-Mn Zn-Cd
High trafk Low traflic density density
0.13 0.27 -0.70 0.36 -0.12 0.81 -0.43 0.93 0.25 -0.52 0.44 -0.06
-0.66 -0.04 -0.02 -0.49 -0.03 0.40 -0.35 -0.74
On the heavily traveled road, the preferential ac- 1970). Contrary to the situation at sites r,, r,, and r,, the cumulation of Cd by roadside soil and grass samples values of these ratios for soil samples are greater than were compared. This was done by determining the the corresponding values for grass samples at sites r, magnitude of the concentration ratios Pb/Cd, ZnKd, and r,. For example, at site r,, the value of Pb/Cd and and Fe/Cd (calculable from Tables 1 and 6) of the soil Fe/Cd ratios for grass samples are 184 and 1524, and grass samples at each location along this road. The respectively, while the corresponding values for these Pb/Cd and Fe/Cd ratios of grass samples at sites r,, r,, ratios describing the soil sample are 265 and 3456, and r, exceed the corresponding values for these ratios respectively. This indicates that, compared with soil, describing the soil sample. For example, at site r,, the grass accumulated Cd in preference to Pb at these sites. values of Pb/Cd and Fe/Cd ratios for grass samples are The Z&d concentration ratio is also evidence that, 272 and 1957, respectively, while the corresponding compared with soil, grass samples generally did not values of these ratios for soil samples are 170 and show much preference between Zn and Cd except at 1523, respectively. This indicates that, compared with site r,, where in comparison with soil, grass accumu- grass, soil accumulated Cd in preference to Pb. This lated Cd in preference to Zn. The Cd accumulation in effect can be related to the pH of the soil, since an preference to Pb and Zn by grass samples can be increase in soil pH will increase the extent of ad- related to aerial contributions and contributions from sorption of Cd and cause an increase in the concen- the soil. Also, at site r,, compared with grass, soil tration of the metal in soil (Largerwerff and Specht accumulated Cd in preference to Zn and this again can
Tabl
e 4.
Con
cent
ratio
n (p
g g-
i) of
hea
vy
met
als
in o
ther
roa
dsid
e so
il of
Iba
dan
Met
ropo
lis
take
n at
$-w
eekl
y in
terv
als.
No.
of
Site
So
il pH
C
r M
n Fe
N
i cu
Zn
C
d A
s Pb
Sb
H
g Sn
Se
sa
mpl
es
Side
roa
d 25
°C
(n)
1 6.
99
(0.1
5)
2 8.
10
(0.3
1)
3 6.
40
(0.2
2)
4 7.
01
(0.2
5)
5 6.
58
(0.3
8)
6 6.
67
(0.3
5)
7 7.
08
(0.2
5)
8 7.
05
(0.4
0)
9 7.
11
(0.5
5)
10
6.58
(0
.25)
11
7.10
(0
.39)
12
6.
90
(0.2
8)
13
7.20
(0
.35)
14
6.94
(0
.36)
Mea
n 6.
98
Ran
ge
1.7
R.S
.D(%
) 5.
75
79.6
” (1
0.9)
b
66.8
(6
.9)
63.8
(2
1.2)
94.8
(1
2.6)
71.6
(2
0.2)
60
.2
(14.
4)
75.8
(3
0.4)
99
.6
(6.9
) 69
.4
(11.
2)
79.4
(2
1.3)
85.2
(1
5.6)
76.2
(1
2.8)
69.4
(6
.5)
104
(16)
78
.2
43.4
17
.0
305
(76)
31
0 (5
4)
264
(82)
28
1 (6
4)
143
(31)
27
9 (4
7)
255
(72)
29
0 (6
2)
229
(60)
14
3 (3
2)
343
(49)
16
9 (6
0)
127
(35)
16
1 (3
0)
236
216
3906
(8
41)
2701
(5
33)
3183
(7
36)
2786
(8
37)
2232
(3
52)
3836
(1
094)
3286
(1
294)
2540
(3
81)
2558
(5
81)
2603
(6
05)
3973
(9
94)
1737
(5
02)
3149
(7
72)
4189
(1
614)
3048
24
52
66.4
(8
.4)
55.6
(5
.8)
27.0
(3
.9)
38.2
(5
.8)
85.4
(2
0.8)
115
(51)
45
.3
(7.8
) 61
.6
(9.8
) 77
.2
(15.
4)
96.2
(1
1.8)
48.2
(1
1.4)
35.2
(6
.9)
23.2
(4
.8)
51.6
(5
.7)
59.0
91
.8
30.8
23
.8
45.2
52.3
(7
.5)
29.8
(4
.7)
15.0
(2
.8)
18.7
(4
.5)
8.94
(2
.52)
22
.4
(5.6
) 37
.2
(4.9
) 24
.8
(4.5
) 12
.9
(1.2
) 13
.9
(4.3
) 80
.5
(35.
2)
59.8
(1
5.4)
26.4
(1
0.4)
66.8
(1
3.5)
33.5
71
.6
67.5
128
1.50
(2
2)
(0.6
4)
102
1.88
(3
5)
(1.6
3)
194
1.32
(5
1)
(0.5
0)
172
2.30
(3
2)
(1.8
5)
190
1.40
(4
0)
(0.5
0)
213
1.76
(5
7)
(0.5
4)
169
0.76
(2
2)
(0.2
4)
183
0.98
(3
4)
(0.3
4)
145
2.70
(2
3)
(0.8
9)
137
1.70
(3
0)
(0.5
2)
131
2.75
(2
5)
(0.9
2)
92.2
0.
78
(32.
2)
(0.1
7)
90.6
2.
69
(17.
4)
(1.1
0)
168
2.05
(3
2)
(0.8
8)
151
1.76
12
2 1.
99
26.0
38
.6
n.d.
n.d.
nd.
27.0
(1
0.5)
21
.2
(4.8
) 31
.4
(3.2
)
n.d.
n.d.
13.4
(2
.7)
30.7
(6
.6)
34.6
(1
1.2)
28.5
(1
0.6)
nd.
26.5
(1
0.2)
N.D
713
2742
(9
2)
(823
) 70
4 25
16
(103
) (6
42)
522
1419
(1
13)
(305
) 38
3 (7
9)
330
(87)
26
1 (3
4)
348
(99)
28
7 (3
1)
252
(47)
35
7 (9
1)
330
(34)
21
7 (4
9)
229
(42)
31
6 (5
1)
375
496
968
(206
) 90
3 (3
21)
935
(149
) 16
13
(484
) 77
4 (1
56)
1194
(2
81)
1065
(3
40)
1161
(1
99)
1355
(2
79)
820
(221
) 16
67
(408
) 13
66
1968
0.82
(0
.24)
0.28
(0
.10)
0.66
(0
.24)
0.48
(0
.18)
0.
67
(0.2
1)
0.48
(0
.13)
0.16
(0
.04)
0.45
(0
.02)
0.
47
(0.2
4)
0.64
(0
.21)
0.51
(0
.10)
0.63
(0
.24)
0.44
(0
.15)
0.35
(0
.15)
0.50
0.
66
42.7
44
.2
34.0
320.
0 (1
10.6
)
nd.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
280.
6 (5
5.2)
nd.
385.
6 (4
2.6)
n.d.
nd.
nd.
N.D
n.d.
n.d.
n.d.
n.d.
n.d.
nd.
nd.
n.d.
nd.
n.d.
n.d.
n.d.
nd.
nd.
N.D
6 6 6 6 6 5 5 6 6 5 6 5 6 6
a Mea
ns
of d
uplic
ate
anal
ysis
an
d ‘n
’ sa
mpl
ing
whe
re
n is
the
num
ber
of s
ampl
es;
b st
anda
rd
devi
atio
n,
o,_,
; n.d
. =
not
dete
cted
; N
.D.
= no
t de
term
ined
.
Heavy metal contamination of roadside soil and grass 91
Table 5. Heavy metal contents of roadside soil as a function of distance from highway r4). All values are in pg g’.
Distance from
highway
(m)
Cr Mn Fe Ni cu Zn Cd No. of
samples
2 41.2” 386 4424 57.6 20.4 67.9 1.28 (13.4)b (75) (1327) (15.3) (3.1) (5.5) (0.32) 6
10 43.5 752 4460 96.2 31.6. 62.4 0.80 (10.3) (78) (1488) (7.9) (7.8) (12.5) (0.32) 6
15 25.2 724 3696 86.6 39.6 50.8 0.46
(7.4) (85) (750) (13.5) (9.8) (10.2) (0.16) 6 25 38.4 1143 2527 67.6 49.9 40.6 0.28
(8.5) (150) (650) (14.2) (8.6) (8.4) (0.10) 5 35 51.4 1490 2411 97.8 56.8 21.9 0.18
(12.3) (140) (491) (21.4) (10.8) (6.2) (0.04) 5
Distance from
highway (m)
As Pb Sb Hg Sn Se No. of
samples
2 n.d. 339 619 0.46 160 (53) (78) (0.15) (36) n.d. 6
10 15.3 278 851 0.35 84.9 (2.9) (53) (111) (0.13) (21.2) n.d. 6
15 7.4 217 754 0.12 96.5 (1.5) (39) (90) (0.01) (33.1) n.d. 6
25 nd. 114 572 nd. 57.3 (18) (99) (17.5) n.d. 5
35 n.d. 71.4 601 n.d. 67.8 (8.2) (133) (18.2) n.d. 5
a concentration; b standard deviation, a,_,; n.d. = not detected.
be related to the pH of soil at this site. Thus, the varied preferential accumulation of Cd by soil and grass samples at different sites depends on the pH and other physicochemical properties of the soil, aerial contribu- tions, and contributions of Cd to grass from the soil.
Acknowledgment-The authors would like to acknowledge the assis- tance received Tom Olabode Kehinde during the collection and analysis of samples.
REFERENCES
Archer, A.; Barrett, R.S. Lead levels in Birmingham dust. Sci. Total Environ. 6: 275-286; 1976.
Biggins, P.D.E.; Harrison, R.M. Chemical speciation of lead compounds in street dust. Environ Sci. Technol. 14: 336-339; 1980.
Bourcier, D.R.; Hindin, E. Lead, iron, chromium and zinc in road run- off at Pulman, Washington. Sci. Total Environ. 12: 205-215; 1979.
Chow, T.J. Lead accumulation in roadside soil and grass. Environ. Sci. Technol. 225: 295-296; 1970.
Day, J.P.; Hart, M.; Robinson, M.S. Lead in urban street dust. Nature 253: 343-345; 1975.
Day, J.P. Lead pollution in Christchurch, New Zealand. J. Sci. 20: 395-406; 1977.
DOE (Department of Environment). Inputs of dangerous substances to water: Proposals for a united system of control. The govem- ment’s consultative proposals for a unified system of tighter controls over the most dangerous substances entering aquatic environments. “The Red List”; July 1988. Available from: DOE, London, UK.
Duggan, M.J.; Williams, S. Lead in dust in city streets. Sci. Total Environ. 7: 91-97; 1977.
Farmer, J.G.; Lyon, T.D.B. Lead in Glasgow street dirt and soil. Sci. Total Environ. 8: 89-93; 1977.
Fergusson, J.E.; Hayes, R.W.; Young, TX; Thiew, S.H. Heavy metal pollution by traftic in Christchurch, New Zealand, lead and cadmium content of dust, soil and plant samples. New Zealand J. Sci. 23: 293-310; 1980.
98 A.A. Olajire and E.T. Ayodele
1.2
0.2
5 10 15 20 25 30 35 40 Distance from Hiqhwoy (ml
Cd
I I I I I I I I 5 10 15 20 2s 30 35 40
Distance from Niqhway (ml
Fig. 2. Regression of metal content of soil on distance from highway. (Metals in parentheses are those where points of deviation of two or more
fall on the same line.)
Heavy metal contamination of roadside soil and grass 99
ooc
360 -
_ 240- i
% - zoo- .- s ‘0 B 160- Y c 8
8 120-
60 -
40 -
0 I I I I I I I 1 5 10 15 20 25 30 35 40
6000- Distoncr from Highway (ml
4600 -
4200-
“0 * 3000- ‘0 E S! f 2400-
; P
1600 _
I 3
I I I I I I 1 IO I3 20 23 30 35 40
Distance from Hiphwoy lml
Fig. 2. Continued.
Tabl
e 6.
Con
cent
ratio
n (p
g 6’
) of
hea
vy
met
als
in r
oads
ide
and
high
way
gr
ass
sam
ples
ta
ken
at 4
-wee
kly
inte
rval
s.
Site
C
r M
n Fe
N
i cu
Zn
C
d A
s Pb
Sb
N
o. o
f H
g Sn
Se
sa
mpl
es
(n)
Side
roa
d
3 9 10
14
Hig
hway
50.6
” 25
0 44
55.4
19
.2
55.8
10
4 0.
50
(5.4
)b
(92)
(1
758.
8)
(5.9
) (1
3.8)
(1
7)
(0.1
0)
43.2
19
7 17
91.8
10
.9
24.4
. 11
1 1.
58
(6.4
) (6
5)
(381
.2)
(2.7
) (7
.5)
(26)
(0
.51)
39
.4
169
2285
.6
6.22
43
.2
107
1.02
(1
0.8)
(3
1)
(682
.8)
(1.5
0)
(9.7
) (3
3)
(0.4
4)
60.8
32
8 29
01.2
27
.6
59.6
12
1 0.
78
(15.
9)
(136
) (1
047.
8)
(12.
4)
(20.
8)
(37)
(0
.19)
n.d
252
645.
2 (1
31)
(87.
9)
n.d.
n.
d.
n.d.
6
370
0.65
n.
d.
(100
) n.
d.
(0.1
8)
n.d.
n.
d.
6 20
5 57
3.4
0.25
(E
) (9
4)
(119
.4)
(0.0
8)
n.d.
n.
d.
5 nd
. 36
1 82
7.8
(189
) (2
48.3
) nd
. n.
d.
n.d.
6
35.3
rl (5
.5)
r2
26.4
(6
.3)
r3
56.8
(9
.8)
r4
37.9
(4
.6)
rs
46.8
(8
.7)
w1
32.2
(5
.2)
w2
25.6
(7
.3)
w3
20.6
(4
.8)
w4
29.2
(6
.8)
w5
35.6
0
(8.9
) 14
.7
(1.8
) M
eans
38
.6
Ran
ge
40.2
R
.S.D
. (%
) 30
.8
243
1879
.4
(59)
(3
55.6
) 10
9 20
35.1
(2
5)
(300
.6)
87.6
22
92.4
(3
5.9)
(5
07.2
) 26
4 24
37.6
(7
0)
(805
.6)
350
2401
.6
(81)
(9
94.8
) 28
0 22
36.6
(7
9)
(720
.4)
228
2173
.4
(60)
(8
01.8
) 35
5 26
78.4
(1
24)
(115
9.0)
18
3 18
88.4
(6
0)
(605
.9)
211
2075
.8
(89)
(8
90.2
) 11
1 98
5 (1
2)
(56)
23
2 23
95
267
2663
28.2
(9
.6)
37.6
(1
2.4)
14
.7
(5.7
) 13
.2
(3.4
) 30
.6
(7.8
) 45
.3
(17.
2)
18.3
(5
.2)
34.8
(1
1.1)
24
.8
(8.6
) 16
.2
(5.7
) 11
.2
(0.9
) 23
.4
39.1
35
.1
27.9
47
.9
65.4
59
.6
0.96
(2
8.4)
(1
7.8)
(0
.36)
22
.4
65.9
1.
14
(10.
3)
(15.
9)
(0.4
0)
26.3
60
.5
0.56
(8
.2)
(16.
3)
(0.2
1)
33.4
54
.8
1.60
(1
1.5)
(8
.9)
(0.5
1)
58.8
80
.9
1.26
(1
5.2)
(3
5.4)
(0
.42)
61
.6
57.2
0.
74
(25.
4)
(26.
4)
(0.3
0)
37.8
43
.5
0.30
(1
2.6)
(1
7.4)
(0
.12)
52
.2
77.8
0.
66
(17.
4)
(26.
4)
(0.2
5)
50.9
47
.3
0.34
(1
3.3)
(9
.2)
(0.1
1)
32.6
49
.4
0.18
(9
.2)
(13.
5)
(0.0
4)
28.9
34
.2
0.47
(1
.9)
(2.8
) (0
.03)
44
.6
74.3
0.
83
43.0
77
.5
1.42
33
.6
35.4
54
.2
n.d.
n.d.
n.d.
23
.6
(5.3
)
n.d.
31
.4
(7.6
) 21
.8
(5.2
) 11
.3
(3.4
) nd
.
N.D
.
261
(56)
57
5 (1
88)
393
(87)
29
4 (1
38)
211
(74)
22
2)
(88)
21
3 (7
1)
730
(155
) 31
4 (1
06)
274
(81)
75
.1
(7.8
) 33
4 52
5 45.2
n.d.
n.
d.
0.35
n.
d.
(0.1
6)
305.
2 0.
48
(91.
5)
(0.1
3)
0.21
n.
d.
(0.0
5)
n.d.
nd
.
n.d.
n.
d.
960.
8 0.
27
(393
.9)
(0.0
8)
1225
.8
0.24
(1
48.6
) (0
.03)
70
0.4
(250
.2)
n.d.
0.
14
n.d.
(0
.06)
n.d.
nd
.
N.D
. N
.D.
21.2
(7
.3)
n.d.
n.d.
nd.
n.d.
nd.
n.d.
11
.5
(4.6
)
n.d.
4.
8 (1
.5)
nd.
N.D
.
n.d.
5
n.d.
6
n.d.
6
n.d.
6
n.d.
5
n.d.
6
n.d.
6 6
n.d.
n.d.
6
n.d.
6
n.d.
1
N.D
. -
a Mea
ns
of d
uplic
ate
anal
ysis
an
d ‘n
’ sa
mpl
ing
b st
anda
rd
devi
atio
n,
a,.,;
n.
d. =
not
det
ecte
d;
??un
cont
amin
ated
re
fere
nce
poin
t; ’ m
eans
of
qui
ntrip
licat
e an
alys
is;
N.D
. =
not
dete
rmin
ed.
g b t L. “9 a
Heavy metal contamination of roadside soil and grass 101
Fergusson, J.E.; Simmonds, P.R. Heavy metal pollution at an intersection involving a busy urban road in Christchurch, New Zealand. 1. Levels of Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb in street dust. New Zealand J. Sci. 26: 219-228; 1983.
Fergusson, J.E. The heavy elements: Chemistry, environmental impact and health effects. Oxford: Pergamon Press; 1990.
Harrison, RM. Toxic metals in street dust and household dust. Sci. Total Environ. 11: 89-97; 1979.
Harrison, R.M.; Laxen, D.P.H.; Wilson, S.J. Chemical associations of lead, cadmium, copper and zinc in street dust and roadside soils. Environ. Sci. Technol. 15: 1378-1383; 1981.
Ho, Y.B. Lead contamination in street dust in Hong Kong. Bull. Environ. Cont. Toxicol. 21: 639-642; 1979.
Hopke, P.K.; Lamb, R.E.; Natusch, D.F.S. Multielement charac- terization of urban roadway dust. Environ. Sci. Technol. 14: 164- 172; 1980.
Lacasse, N.L. Lead in soil and plants. Its relationship to traftic volume and proximity to highways. Environ. Sci. Technol. 4: 237-238; 1970.
LargerwertT, J.V.; Specht, A. W. Contamination of roadside soil and vegetation with cadmium, nickel, lead and zinc. Environ. Sci. Technol. 4: 583-586; 1970.
Lazrus, A.L.; Lorange, E.; Lodge, J.P. Lead and other metal ions in U.S. precipitation. Environ. Sci. Technol. 4: 55-581; 1970.
Motto, H.L.; Daniel, R.H.; Chilko, D.M.; Motto, C.K. Lead in soils and plants: Its relationship to traffic volume and proximity to highways. Environ. Sci. Technol. 4(3): 231-237; 1970.
Olson, K.W.; Skogerboe, R.K. Identification of soil lead compounds from automobile sources. Environ. Sci. Technol. 9: 227-230; 1975.
O’Neill, P. Heavy metals in soils, chapter 5. In: Alloway, B.J., ed. Glasgow: Blackie and Son; 1990.
Paciga, J.J.; Jervis, R.E. Multielement size characterization of urban aerosols. Environ. Sci Technol. 10: 1024-1028; 1976.
Pacyna, J.M. Lead, mercury, cadmium and arsenic in the environment. In: Hutchinson, T.C.; Meema, K.M., eds. SCOPE 3 1. Chichester: John Wiley and Sons; 1987.
Revitt, D.M.; Ellis, J.B. Rain water leachates of heavy metals in road surface sediments. Water Res. 14: 1403-1407; 1980.
Schuck, E.A. Lead in soil and plants: Its relationship to traffic volume and proximity to highways. Environ. Sci. Technol. 4: 238-239; 1970.
Solomon, R.L.; Hartford, J.W. Lead and cadmium in dusts and soils in a small urban community. Environ. Sci. Technol. 10: 773-777; 1976.
Steinnes, E. Heavy metals in soils, chapter 11. In: Alloway, B.J., ed. Glasgow: Blackie; 1990.
van Hassel, J.H.; Ney, J.J.; Garling, D.L. Seasonal variations in the heavy metal concentrations of sediments influenced by highways of different traffic volumes. Bull. Environ. Contam. Toxicoi. 23: 592-596; 1979.
Ward, N.I.; Brooks, R.R.; Roberts, E.; Boswell, CR. Heavy metal pollution from automotive emissions and its effect on roadside soils and pasture species in New Zealand. Environ. Sci. Technol. 11: 917-920; 1977.
