Contamination of roadside soil and grass with heavy metals

Contamination of roadside soil and grass with heavy metals

Environmat imnational, Vol. 23,No. 1, pp. 91-101.1997 copyright01997 Fhvicx Science Ltd F’rintcdin the USA. All rights resewed 0160-4120/97 Sl7.00+.00...

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Environmat imnational, Vol. 23,No. 1, pp. 91-101.1997 copyright01997 Fhvicx Science Ltd F’rintcdin the USA. All rights resewed 0160-4120/97 Sl7.00+.00

Pergamon

PIIS016Q4120(96)00080-3

CONTAMINATION OF ROADSIDE WITH HEAVY METALS

SOIL AND GRASS

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

density. This contamination of roadside soil and vegetation 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 production (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.

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

91

A.A. Olajire and E.T. Ayodele

92

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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, IbadanIlorin (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. Fortytwo 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 mechanics, battery smelter, and tire vulcanizer, respectively. 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 uniform 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 (approximately 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

A reagent blank was prepared using a 50 cm3 mixture of nitric and perchloric acids in a 250 cm3 round-bottomed quick-fit Pyrex flask, and the entire sequence of steps was followed as described for the sample preparation. The samples were analyzed by atomic absorption spectrophotometry using Chem Tech Analytical alpha 4 model operated per the instrument’s manual. The instrument was calibrated using mixed calibration. 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 deviations) for 5 to 6 samples taken from each site at weekly intervals, October-November 1995. It is surprising 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 procedure. 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 suspension 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 traffic 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
93

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 roadside 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 indication 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 producer of Exide Battery. No detectable traces of selenium 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 roadside soil with increasing distance from the road, indicating their relation to traffic. The concentrations of Cu, Ni, Cr, and Mn, with positive regression coefficients, increase in roadside soil with increasing distance 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 automobiles. 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 Znoxide and Zn-diethyl or dimethyl carbamate in vulcanization (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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Heavy metal contamination of roadside soil and grass

Table 2. Statistical” assessment of heavy metal contents of roadside soil from two areas of different traffk density. Area

Cr

Mn

51.6 15.7

196 59.2

39.0 34.4

131 25.3

Fe

Ni

cu

Zn

Cd

Pb

2613 41.2

38.9 30.8

31.4 46.5

86.1 35.9

1.36 31.8

307 19.5

2234 12.7

28.0 30.5

20.3 37.7

92.6 16.4

0.91 39.6

356 24.7

High traffic density (5 samples) Means (ug g-‘) R.S.D. (%) Low traffic density (5 samples) Means (pg g-r) R.S.D. (%) t-values

1.61

1.04

0.76

1.50

1.34

-0.38

1.60

-0.93

’ Critical value of Idfor 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 density 0.13 -0.70 -0.12 -0.43 0.25 0.44 -0.66 -0.02 -0.03 -0.35

On the heavily traveled road, the preferential accumulation of Cd by roadside soil and grass samples were compared. This was done by determining the magnitude of the concentration ratios Pb/Cd, ZnKd, and Fe/Cd (calculable from Tables 1 and 6) of the soil and grass samples at each location along this road. The Pb/Cd and Fe/Cd ratios of grass samples at sites r,, r,, and r, exceed the corresponding values for these ratios describing the soil sample. For example, at site r,, the values of Pb/Cd and Fe/Cd ratios for grass samples are 272 and 1957, respectively, while the corresponding values of these ratios for soil samples are 170 and 1523, respectively. This indicates that, compared with grass, soil accumulated Cd in preference to Pb. This effect can be related to the pH of the soil, since an increase in soil pH will increase the extent of adsorption of Cd and cause an increase in the concentration of the metal in soil (Largerwerff and Specht

Low traflic density 0.27 0.36 0.81 0.93 -0.52 -0.06 -0.04 -0.49 0.40 -0.74

1970). Contrary to the situation at sites r,, r,, and r,, the values of these ratios for soil samples are greater than the corresponding values for grass samples at sites r, and r,. For example, at site r,, the value of Pb/Cd and Fe/Cd ratios for grass samples are 184 and 1524, respectively, while the corresponding values for these ratios describing the soil sample are 265 and 3456, respectively. This indicates that, compared with soil, grass accumulated Cd in preference to Pb at these sites. The Z&d concentration ratio is also evidence that, compared with soil, grass samples generally did not show much preference between Zn and Cd except at site r,, where in comparison with soil, grass accumulated Cd in preference to Zn. The Cd accumulation in preference to Pb and Zn by grass samples can be related to aerial contributions and contributions from the soil. Also, at site r,, compared with grass, soil accumulated Cd in preference to Zn and this again can

94.8 (12.6)

71.6 (20.2)

60.2 (14.4)

75.8 (30.4)

99.6

(6.9) 69.4 (11.2)

79.4 (21.3)

85.2 (15.6)

76.2 (12.8)

69.4

6.40 (0.22)

7.01 (0.25)

6.58 (0.38)

6.67 (0.35)

7.08 (0.25)

7.05 (0.40)

7.11 (0.55)

6.58 (0.25)

7.10 (0.39)

6.90 (0.28)

7.20 (0.35)

6.94 (0.36)

6.98 1.7 5.75

3

4

5

6

7

8

9

10

11

12

13

14

Mean Range R.S.D(%)

(994) 1737 (502) 3149

(49) 169

(30) 236 216 30.8

(16) 78.2 43.4 17.0 3048 2452 23.8

(5.7) 59.0 91.8 45.2

(4.8) 51.6

(6.9) 23.2

35.2

48.2 (11.4)

96.2 (11.8)

(9.8) 77.2 (15.4)

(7.8) 61.6

115 (51) 45.3

(5.8) 85.4 (20.8)

(3.9) 38.2

(5.8) 27.0

33.5 71.6 67.5

66.8 (13.5)

26.4 (10.4)

59.8 (15.4)

(4.3) 80.5 (35.2)

(1.2) 13.9

(4.5) 12.9

(4.9) 24.8

(5.6) 37.2

22.4

(4.5) 8.94 (2.52)

(2.8) 18.7

(4.7) 15.0

(7.5) 29.8

52.3

66.4 (8.4) 55.6

cu

Ni

(32) 151 122 26.0

168

90.6 (17.4)

(25) 92.2 (32.2)

(30) 131

(23) 137

(32) 190 (40) 213 (57) 169 (22) 183 (34) 145

(51) 172

(35) 194

(22) 102

128

Zn

1.76 1.99 38.6

2.05 (0.88)

2.69 (1.10)

0.78 (0.17)

2.75 (0.92)

1.70 (0.52)

2.70 (0.89)

0.98 (0.34)

0.76 (0.24)

1.76 (0.54)

1.40 (0.50)

2.30 (1.85)

1.32 (0.50)

1.88 (1.63)

1.50 (0.64)

Cd

(31) 252

n.d.

N.D

26.5 (10.2)

nd.

28.5 (10.6)

(51) 375 496 42.7

(42) 316

(49) 229

(34) 217

(91) 330

(47) 357

(99) 287

n.d.

13.4 (2.7) 30.7 (6.6) 34.6 (11.2)

(34) 348

(87) 261

(79) 330

383

522 (113)

(92) 704 (103)

713

Pb

(3.2)

(4.8) 31.4

21.2

27.0 (10.5)

nd.

n.d.

n.d.

As

(408) 1366 1968 44.2

(221) 1667

(279) 820

(199) 1355

(340) 1161

(281) 1065

(156) 1194

(484) 774

(149) 1613

(321) 935

(206) 903

968

1419 (305)

(823) 2516 (642)

2742

Sb

0.50 0.66 34.0

0.35 (0.15)

0.44 (0.15)

0.63 (0.24)

0.51 (0.10)

0.64 (0.21)

0.47 (0.24)

0.45 (0.02)

0.16 (0.04)

0.48 (0.13)

0.67 (0.21)

0.48 (0.18)

0.66 (0.24)

0.28 (0.10)

0.82 (0.24)

Hg

N.D

nd.

nd.

n.d.

385.6 (42.6)

nd.

280.6 (55.2)

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

nd.

320.0 (110.6)

Sn

a Means of duplicate analysis and ‘n’ sampling where n is the number of samples; b standard deviation, o,_,; n.d. = not detected; N.D. = not determined.

(35) 161

(6.5) 104

(60) 127 (772) 4189 (1614)

(605) 3973

(32) 343

(62) 229

(60) 143

3286 (1294) 2540 (381) 2558 (581) 2603

(72) 290

(47) 255

(31) 279

(64) 143

(82) 281 (837) 2232 (352) 3836 (1094)

66.8

8.10 (0.3 1)

2

(54) 264

(841) 2701 (533) 3183 (736) 2786

(76) 310

(6.9) 63.8 (21.2)

3906

305

79.6” (10.9)b

6.99 (0.15)

1

Fe

Mn

Cr

Soil pH 25°C

(pg g-i) of heavy metals in other roadside soil of Ibadan Metropolis taken at $-weekly intervals.

Site Side road

Table 4. Concentration

N.D

nd.

nd.

n.d.

n.d.

n.d.

nd.

n.d.

nd.

nd.

n.d.

n.d.

n.d.

n.d.

n.d.

Se

6

6

5

6

5

6

6

5

5

6

6

6

6

6

No. of samples (n)

91

Heavy metal contamination of roadside soil and grass

Table 5. Heavy metal contents of roadside soil as a function of distance from highway r4). All values are in pg g’.

Cr

Mn

Fe

Ni

cu

Zn

Cd

No. of samples

41.2” (13.4)b

386 (75)

4424 (1327)

57.6 (15.3)

20.4

67.9

6

43.5 (10.3)

752 (78)

4460 (1488)

96.2

0.80 (0.32)

6

15

25.2

724 (85) 1143 (150)

50.8 (10.2)

0.46 (0.16)

6

25

(7.4) 38.4 (8.5)

3696 (750)

(7.9) 86.6 (13.5)

(5.5) 62.4 (12.5)

1.28 (0.32)

10

(3.1) 31.6.

2527 (650)

67.6 (14.2)

40.6

0.28 (0.10)

5

51.4 (12.3)

(140)

2411 (491)

97.8 (21.4)

(6.2)

0.18 (0.04)

5

Sn

Se

No. of samples

n.d.

6

n.d.

6

Distance from highway (m) 2

35

Distance from highway (m)

1490

(7.8) 39.6 (9.8) 49.9 (8.6) 56.8 (10.8)

Pb

Sb

Hg

n.d.

339

619

15.3

(78) 851

0.46 (0.15)

10

(53) 278

15

(2.9) 7.4

(53) 217

(111) 754

25

(1.5) nd.

(39) 114

(90) 572

35

n.d.

(18) 71.4

(99) 601

2

As

(8.2) a concentration;

(8.4) 21.9

160

0.35 (0.13)

(36) 84.9 (21.2)

0.12 (0.01)

96.5 (33.1)

n.d.

6

nd.

57.3 (17.5)

n.d.

5

n.d.

67.8 (18.2)

n.d.

5

(133)

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 contributions, and contributions of Cd to grass from the soil. authors would like to acknowledge the assistance received Tom Olabode Kehinde during the collection and analysis of samples.

Acknowledgment-The

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 runoff 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 govemment’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

5

10

15

Distance

20

from

30

25

Hiqhwoy

35

40

(ml

1.2

0.2

Cd I 5

I 10

I

I 20

15

Distance

from

Niqhway

I 2s

I 30

I 35

I 40

(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

99

grass

ooc

360 -

_

240-

i % zoo.s ‘0 B

160-

Y c 8 8

120-

60 -

40 -

I 5

0

I

I

15

Distoncr

6000-

4600

I 10

from

I

20

Highway

25

I

30

I

35

1

40

(ml

-

4200-

“0 * 3000‘0 E S! f

2400-

; P

1600 _

I

I

I

I

I

I

3

IO

I3

20

23

30

Distance

from

Hiphwoy

Fig. 2. Continued.

lml

I 35

1 40

(25) 87.6 (35.9) 264

(70) 350

(81) 280

(79) 228

(60)

(6.3) 56.8 (9.8) 37.9

(4.6) 46.8

(8.7) 32.2

(5.2) 25.6

(7.3) 20.6

(4.8) 29.2

(6.8) 35.6

rs

w1

w2

w3

w4

w5

(89) 111

(12) 232 267 35.1

(8.9) 14.7

(1.8) 38.6 40.2 30.8

(60) 211

(56) 2395 2663 27.9

1879.4 (355.6) 2035.1 (300.6) 2292.4 (507.2) 2437.6 (805.6) 2401.6 (994.8) 2236.6 (720.4) 2173.4 (801.8) 2678.4 (1159.0) 1888.4 (605.9) 2075.8 (890.2) 985

4455.4 (1758.8) 1791.8 (381.2) 2285.6 (682.8) 2901.2 (1047.8)

Fe

(0.9) 23.4 39.1 47.9

(5.7) 11.2

(8.6) 16.2

(5.2) 34.8 (11.1) 24.8

(7.8) 45.3 (17.2) 18.3

(3.4) 30.6

(5.7) 13.2

(9.6) 37.6 (12.4) 14.7

28.2

(2.7) 6.22 (1.50) 27.6 (12.4)

19.2 (5.9) 10.9

Ni

(1.9) 44.6 43.0 33.6

(9.2) 28.9

65.4 (28.4) 22.4 (10.3) 26.3 (8.2) 33.4 (11.5) 58.8 (15.2) 61.6 (25.4) 37.8 (12.6) 52.2 (17.4) 50.9 (13.3) 32.6

55.8 (13.8) 24.4. (7.5) 43.2 (9.7) 59.6 (20.8)

cu

(2.8) 74.3 77.5 35.4

(9.2) 49.4 (13.5) 34.2

59.6 (17.8) 65.9 (15.9) 60.5 (16.3) 54.8 (8.9) 80.9 (35.4) 57.2 (26.4) 43.5 (17.4) 77.8 (26.4) 47.3

104 (17) 111 (26) 107 (33) 121 (37)

Zn

0.96 (0.36) 1.14 (0.40) 0.56 (0.21) 1.60 (0.51) 1.26 (0.42) 0.74 (0.30) 0.30 (0.12) 0.66 (0.25) 0.34 (0.11) 0.18 (0.04) 0.47 (0.03) 0.83 1.42 54.2

0.50 (0.10) 1.58 (0.51) 1.02 (0.44) 0.78 (0.19)

Cd

??

(7.8) 334 525 45.2

(81) 75.1

(106) 274

(138) 211 (74) 222) (88) 213 (71) 730 (155) 314

261 (56) 575 (188) 393 (87) 294

(94) 361 (189)

(131) 370 (100) 205

252

Pb

uncontaminated

N.D.

(3.4) nd.

(5.2) 11.3

(7.6) 21.8

n.d. 31.4

(5.3)

n.d. 23.6

n.d.

n.d.

(E) nd.

n.d.

n.d

As

N.D.

nd.

n.d. 0.14 (0.06)

n.d. 0.27 (0.08) 0.24 (0.03)

nd.

0.35 (0.16) 0.48 (0.13) 0.21 (0.05)

n.d.

nd.

n.d. 0.65 (0.18) 0.25 (0.08)

Hg

N.D.

n.d.

nd. N.D.

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

(1.5)

n.d. 4.8

(4.6)

n.d. 11.5

nd.

n.d.

nd.

n.d.

n.d.

(7.3)

21.2

n.d.

n.d.

n.d.

n.d. n.d.

n.d.

Se

n.d.

Sn

reference point; ’means of quintriplicate

N.D.

n.d.

n.d.

n.d. 960.8 (393.9) 1225.8 (148.6) 700.4 (250.2)

n.d.

n.d.

n.d. 305.2 (91.5)

n.d.

n.d. 573.4 (119.4) 827.8 (248.3)

645.2 (87.9)

Sb

(pg 6’) of heavy metals in roadside and highway grass samples taken at 4-weekly intervals.

a Means of duplicate analysis and ‘n’ sampling b standard deviation, a,.,; n.d. = not detected; N.D. = not determined.

Means Range R.S.D. (%)

0

r4

r3

355 (124) 183

(59) 109

rl r2

243

250 (92) 197 (65) 169 (31) 328 (136)

Mn

(5.5) 26.4

50.6” (5.4)b 43.2 (6.4) 39.4 (10.8) 60.8 (15.9)

Cr

35.3

Highway

14

10

3 9

Side road

Site

Table 6. Concentration

analysis;

-

1

6

6

6 6

6

5

6

6

6

5

6

5

6

6

(n)

No. of samples

a

“9

L.t

b

g

Heavy metal contamination of roadside soil and grass

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 characterization of urban roadway dust. Environ. Sci. Technol. 14: 164172; 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.

101

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.