**5. Assessment of heavy metal contamination in soil**

Assessment of soil contamination was performed by the contamination index (Pi ) and inte‐ grated contamination index (Pc) as expressed by fuzzy functions [82, 29, 28]. Class I criteria [60] could be used as no-polluted threshold; Class II as lowly polluted threshold value; and while Class III as highly polluted threshold value. Pi values ≤ 1 indicate no contamination; 1 ≤ P<sup>i</sup> ≤ 2 indicates low contamination; 2 ≤ Pi ≤ 3 indicates moderate contamination; while Pi > 3 indicates high contamination.

differences in the metal contamination profile. Compared to average concentrations in urban soils in the world, the mean concentrations of Pb and Cu are up to 2—4 times higher in some cases but still less than London, Naples and Palermo. In the case of Cd, it is many times higher than Kattedan (India). Zn and Cr contents do not differ much; still they are less than those of Naples and Madrid. Ni content is more than almost all European cities, but less than Kattedan and Firozabad in India. Co values are less than those reported from other industrial regions

**City Pb Cd Zn Cu Co Cr Ni As Reference London** 294 - 183 73 - - - - [75] **Madrid** 161 - 210 72 - 75 14 - [76] **Rostock** 83 - 100 35 - 48 30 - [77] **Sevilla** 161 - 107 64.6 - 42.8 23.5 - [19] **Belgrade** 53.2 - 129.1 29 - 33.2 67.4 - [18] **Palermo** 253 - 151 77 - 39 19.1 - [72] **Naples** 262 - 251 11 - 74 - - [21] **Nanjing** 107.3 - 162.6 66.1 - 84.7 - - [78] **Hong Kong** 93.4 - 168 24.8 - n.a. - - [79] **Kattedan** 195-6241 0.08-0.16 130-3191 72-1450 12-36 77-586 63-494 0.10-0.21 [80] **Firozabad** 35.5-781 3.64-107 76.4-1247 22.4-300 10.9-63.7 19.1-158 23-218 9.25-204 [29]

**Zone 1** 200 13.4 116 30.4 3.70 40.7 33.6 17.2 **Zone 2** 261 20.3 173 57.0 9.60 86.7 63.5 25.2 **Zone 3** 125 10.2 144 25.7 4.96 28.1 23.3 13.8

**Table 8.** Average heavy metal concentrations in urban soils from different cities across the world (mg kg−1)

Assessment of soil contamination was performed by the contamination index (Pi

grated contamination index (Pc) as expressed by fuzzy functions [82, 29, 28]. Class I criteria [60] could be used as no-polluted threshold; Class II as lowly polluted threshold value; and while

) and inte‐

≤ 2

values ≤ 1 indicate no contamination; 1 ≤ P<sup>i</sup>

**5. Assessment of heavy metal contamination in soil**

Class III as highly polluted threshold value. Pi

It is encouraging to note that the mean concentrations of individual metals are below those reported from other industrial hubs within India i.e. Kattedan (Andhra Pradesh) [except Cd and As] and Firozabad (Uttar Pradesh). Kattedan Industrial Development Area (KIDA) is a major industrial area of Andhra Pradesh and houses 400–500 industries, including 150 large scale industries and 300 small-scale industries. Major sources of metals pollution are battery, electrode, oil refining, metal plating, textile, pharmaceutical, chemical paints, rubber, petro‐ chemicals, glass, therapeutics, and Pb extraction facilities [81]. This is also one of the contami‐ nated areas identified by the Central Pollution Control Board (CPCB) in New Delhi, and referred to as an ecological disaster area [81]. Firozabad is the hub of the Indian Glass industry.

of India. As content is less than that of Firozabad.

558 Environmental Risk Assessment of Soil Contamination

**Present Study**

Individual elements displayed remarkably different patterns of accumulation in soils. Furthermore, observed differences in the magnitude of accumulation suggest that the relative contribution of the individual elements to total heavy metal contamination varies. Figure 4 shows the proportions of contamination levels (from Pi values) in the soil samples from all the sites studied. Except for 76% samples from zone 2, which showed moderate Pb contamination, the rest exhibited low contamination zone as did all samples from zones 1 and 3. In case of Cd, all samples were in the high contamination zone. For Zn, 24% samples from zone 2 were moderately contaminated while 72%, 76%, and 100% samples from zones 1, 2, and 3, respec‐ tively were in the low contamination range. For Cu, 88% samples from zone 2 were moderately contaminated while 36% and 12% samples, from zones 1 and 2, respectively were in the low contamination range. All samples from zone 3 indicated no contamination. Except for zone 2 (20% samples) in the low contamination zone, the remaining samples did not indicate Cr contamination. For Ni, 12% and 72% samples from zones 1 and 2, respectively were moderately contaminated while 16% and 22% samples from, respectively were in the low contamination range. All samples from zone 3 indicated no contamination. In the case of As, 64%, 100%, and 60% samples from zones 1, 2, and 3 were in the low contamination range.

**Figure 4.** Contamination indices (Pi) of heavy metals in soil samples

Thus, zone 1 was found to be lowly contaminated with Pb, Zn, Cu, Ni and As but highly contaminated with Cd. Zone 2 exhibited low to moderate contamination of Pb, Zn, Cu, Ni; low Cr and As contamination; and high Cd contamination. Zone 3 was lowly polluted with Pb and Zn. As contamination ranged from none to low. No Cu, Cr and Ni contamination was observed. These results agree with the findings regarding metal contamination of soil due to the glass industry at Firozabad, India [29]. Of the nine elements studied, Zn, Cd, and As showed a

**Pc**

greater accumulation in all soils, whereas, accumulation of Ni and Cu was high in limited samples.

Integrated Contamination Indices (Pc) were calculated for all soils to assess the extent of heavy metal contamination at the sites. Pc is defined as the summation of the difference between the contamination index for each metal and 1 (one). It is categorized under the following heads: Pc ≤ 0 no contamination; 0 ≤ Pc ≤ 7 low contamination; 7 ≤ Pc ≤ 21 moderate contamination; Pc > 21 high contamination. Threshold values for Co could not be obtained hence this metals was excluded in the calculation. A clear ascending trend is visible in the Pc values for all sites (Figure 5). Pc values generally show a moderate to high contamination at studied sites. The Pc indices indicate that 45% sampling locations fall in the moderate contamination while 55% of the samples fall in the high contamination range. All the samples from zone 2 fell under the high contamination category. While in zone 1, 60% samples come under moderate and 40% under high contamination level category. In zone 3, 76% and 24% samples were in the moderate and high contamination range, respectively.

**Figure 5.** Integrated contamination indices (Pc) of soil samples. Black and gray lines are the upper threshold values of moderate and low contamination, respectively

The effect of the glass industry on urban soil metal characterization was assessed at 25 test sites at Firozabad, India [29]. The area is characterized by little or no monitoring of industrial processes, usage and disposal of hazardous chemicals. A comprehensive profile of Zn, Mn, Co, Cd, Pb, Cr, Ni, Cu and As contamination was obtained. Zn, Cd, and As showed a greater accumulation in all soils, whereas, accumulation of Ni and Cu was high in limited samples. Integrated contamination indices (Pc) indicate that 60% of the sites were in the high contami‐ nation range and 28% were in the moderate contamination range with just 12% sites on the border of the moderate to low contamination range. [83] assessed the impact of both landuse and soil textures on Cd, Zn, Pb and Cu based on samples collected from the major landuse/ landcover pattern of Dutch forests and aerable soils drawn from six different sites. Metal content in agricultural and industrial soil is found to be higher than the forest soil.

The fact that no Pc value in the present investigation fell within the low contamination range was not surprising, given the fact that the study was being carried out in an area which has already been contaminated with metals, but moderate to high indices in zone 1 and 2 are alarming because these include heavily populated areas. The local populace is, thus, exposed to wide range of historically well established toxins and even carcinogens. The situation is surely compounded by vehicular pollution at urban sites (1-10). Vehicular emissions are a significant source of many pollutants [21, 84].
