Effects of sewage water irrigation of cabbage to soil geochemical properties and products safety in peri-urban Peshawar, Pakistan Hidayat Ullah & Ikhtiar Khan
Environmental Monitoring and Assessment An International Journal Devoted to Progress in the Use of Monitoring Data in Assessing Environmental Risks to Man and the Environment ISSN 0167-6369 Volume 187 Number 3 Environ Monit Assess (2015) 187:1-12 DOI 10.1007/s10661-015-4344-6
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Author's personal copy Environ Monit Assess (2015) 187: 126 DOI 10.1007/s10661-015-4344-6
Effects of sewage water irrigation of cabbage to soil geochemical properties and products safety in peri-urban Peshawar, Pakistan Hidayat Ullah & Ikhtiar Khan
Received: 6 April 2014 / Accepted: 9 February 2015 / Published online: 20 February 2015 # Springer International Publishing Switzerland 2015
Abstract Irrigation of agricultural land with municipal wastewater has become a serious environmental issue due to soil contamination. The objective of the present study was to investigate the extent of contamination of vegetables grown on soil irrigated with untreated sewage water for the last four decades in suburban Peshawar. Samples of sewage water, soil, and vegetables were collected from three different sectors selected for the study. Heavy metals like Pb, Cr, Cd, Cu, Zn, and Ni in the three media were determined with atomic absorption spectrometer (AAS). Statistical analysis of data revealed that the distribution order of these metals is quite different in the analyzed samples. Some of the heavy metals, viz., Cr, Cd, Zn, and Ni, have high skewness with non-normal frequency distribution. The soil of polluted areas showed highest mean concentration of Zn (51.25 mg kg−1), followed by Pb (43.51 mg kg−1), Cu (43.3 mg kg−1), Ni (37.05 mg kg−1), Cr (28.18 mg kg−1), and Cd (8.51 mg kg−1), which were 43, 22, 33, 26, 20, and 6 times higher than the control area, respectively. The ammonium bicarbonate diethylenetriaminepenta acetic acid (AB-DTPA) extractable concentrations of Ni, Cr, and Cu in soil of polluted sectors were 12, 10, and 10 times greater than the those in control sector,
H. Ullah (*) Institute of Chemical Sciences, Gomal University, Dera Ismail Khan, Pakistan e-mail:
[email protected] I. Khan Institute of Chemical Sciences, University of Peshawar, Peshawar, Pakistan
respectively. Linear regression analysis revealed that enhanced levels of these toxic heavy metals in cabbage (Brassica oleracea) were strongly correlated with extractable and total heavy metal concentration in the soil. Significant difference (at PPb> Cr>Ni>Cd. From the statistical data on metal distribution in sewage-contaminated water of less polluted area,
Table 3 Inferential statistics of chemical properties of soil irrigated with tube well and sewage water in selected sectors of Peshawar SS
Df
MSE
LSD
F
P value
pH
Between sectors Within sectors
2.237 0.627
2 33
1.118 0.019
0.81
58.878
0.0001
EC
Between sectors Within sectors
0.314 0.187
2 33
0.157 0.006
0.004
27.685
0.0001
OM
Between sectors Within sectors
4.083 1.777
2 33
2.041 0.054
0.35
37.913
0.0001
SD standard deviation, EC electrical conductivity, OM organic matter, LSD least significant difference
Author's personal copy 126 Page 6 of 12
Environ Monit Assess (2015) 187: 126
Table 4 Descriptive statistics of toxic heavy metal concentration levels (mg L−1) in sewage and tube well water of selected sectors in Peshawar HPS M
LPS Min
Max
Mn±SD
SW
Mn
CS Max
Mn±SD
SW
Min
Max
Mn±SD
SW
−0.53
0.871
1.127
1.038±0.09
−1.24
0.008
0.018
0.012±0.004
0.32
0.28
4.924
17.42
12.051±5.16
−0.57
0.005
0.015
0.010±0.003
−0.54
0.023±0.002
0.31
0.011
0.019
0.015±0.003
0.23
0.001
0.007
0.003±0.002
0.45
0.557±0.072
−0.16
0.291
0.513
0.386±0.080
0.75
0.011
0.022
0.016±0.004
−0.18
0.077
0.082±0.005
0.66
0.055
0.075
0.064±0.007
0.55
0.009
0.019
0.013±0.003
0.29
0.578
0.649±0.067
0.29
0.376
0.513
0.430±0.052
0.67
0.005
0.014
0.009±0.003
0.07
Pb
0.975
1.427
Cr
5.613
5.613
Cd
0.021
0.021
Cu
0.471
0.471
Zn
0.077
Ni
0.578
1.225±0.188 13.735±6.99
M metals, Max maximum, Min minimum, Mn mean, SW skewness, HPS highly polluted sector, LPS less polluted sector, CS control sector
it is clear that Cr, Pb, and Ni are the dominant metals. Recorded mean concentrations of Cr 12.051 mg L−1, Pb 1.038 mg L−1, and Ni 0.430 mg L−1 were followed by Cu 0.386 mg L − 1 , Zn 0.075 mg L − 1 , and Cd 0.019 mg L−1. In highly polluted area, the metal distribution followed the same pattern with mean concentration of Cr 13.735 mg L−1, Pb 1.225 mg L−1, Ni 0.649 mg L−1, Cu 0.557 mg L−1, Zn 0.082 mg L−1, and Cd 0.023 mg L−1. The order of distribution of toxic heavy metals in sewage-contaminated water for both sectors (LPS and HPS) was Cr>Pb>Ni>Cu>Zn>Cd. The potential sources of dominant heavy metals Cr, Pb, Ni, and Cd in the sewage-contaminated water are their respective compounds used in various local industries, e.g., dyes, modifiers, and catalysts. Average Cr concentration at the level of 12.893 mg L−1 in sewage-contaminated water of both sectors found in this study is much higher than the maximum permissible limits of 0.1 mg L−1 for Cr in
effluents to be released to agricultural land (Tiwana et al. 1987). Earlier reports found higher concentrations of Cu and Cd in sewage-contaminated water, industrial effluents, and surface and subsurface groundwater in Medak district, India (Shivkumar and Biksham 1995). The mean concentration of Zn in the present study was lower than those found in sewage water of Hassanabdal and Faisalabad Cities in the Punjab province of Pakistan (Butt et al. 2005). In this work, average Ni concentration (0.539 mg L−1) in sewage-contaminated water collected from both sectors was much higher than the maximum permissible limits of 0.005 mg L−1 of Ni in effluents to be released to agricultural land (Tiwana et al. 1987). Elemental analysis of extractable metal concentration in soil The data distribution of AB-DTPA extractable concentration of selected toxic heavy metals in soil irrigated
Table 5 Descriptive statistics for AB-DTPA extractable concentration levels (mg kg−1) of toxic heavy metals in soil of selected sectors of Peshawar HPS
LPS
CS
M
Min
Max
Mn±SD
SW
Mn
Max
Mn±SD
SW
Min
Max
Mn±SD
SW
Pb
5.86
11.21
8.861±2.04
−0.36
5.67
8.24
7.010±0.85
−0.24
1.75
2.22
1.95±0.18
0.66
Cr
0.86
1.68
1.206±0.35
0.33
0.28
0.65
0.446±0.15
0.28
0.07
0.09
0.07±0.01
0.55
Cd
0.41
0.89
0.575±0.18
1.21
0.25
0.71
0.458±0.15
0.51
0.21
0.25
0.23±0.02
−0.15
Cu
6.46
12.41
9.665±2.21
−0.14
3.08
4.95
3.913±0.81
0.46
0.54
0.82
0.66±0.09
1.09
Zn
3.90
8.75
5.796±1.93
0.78
2.57
4.21
3.611±0.64
−0.86
0.75
0.96
0.82±0.08
1.19
Ni
3.45
5.91
4.468±0.85
0.85
1.46
2.59
2.185±0.40
−1.39
0.22
0.30
0.26±0.03
−0.26
M metals, Max maximum, Min minimum, Mn mean, SW skewness, HPS highly polluted sector, LPS less polluted sector, CS control sector
Author's personal copy Environ Monit Assess (2015) 187: 126
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Table 6 Descriptive statistics of total heavy metal concentration levels (mg kg−1) in soil of selected sectors in Peshawar HPS
LPS SW
Mn
CS
M
Min
Max
Mn±SD
Max
Mn±SD
SW
Min
Max
Mn±SD
SW
Pb
34.9
51.8
43.8±7.1
−0.3
40.7
Cr
30.1
38.7
34.1±3.5
0.2
18.6
46.8
43.2±2.3
0.6
19.8
22.5
21.0±1.1
0.4
25.2
22.3±2.4
−0.5
6.9
8.3
7.2±0.4
Cd
7.3
13.5
9.1±2.3
1.7
6.7
−0.9
9.3
7.9±0.9
0.3
1.9
3.2
2.6±0.5
−0.5
Cu
40.1
57.3
48.0±6.8
0.5
33.6
42.5
38.5±3.6
−0.5
9.2
11.4
10.3±0.7
0.01
Zn
48.4
59.6
55.2±4.2
−0.7
40.9
52.6
47.3±4.7
−0.1
7.7
8.6
8.2±0.4
−0.4
Ni
38.7
45.1
41.5±2.2
0.6
22.3
37.3
32.6±5.6
−1.4
9.8
11.6
10.5±0.7
1.2
M metals, Max maximum, Min minimum, Mn mean, SW skewness, HPS highly polluted sector, LPS less polluted sector, CS control sector
with tube well water (CS) showed that Pb, Zn, and Cu are the dominant metals with Pb having a mean concentration of 1.953 mg kg−1 followed by Zn 0.823 mg kg−1, Cu 0. 65 9 m g kg − 1 , N i 0. 26 1 m g kg − 1 , C d 0.226 mg kg−1, and Cr 0.077 mg kg−1 (Table 5). In the less polluted sector, mean concentration of Pb 7.010 mg kg−1 was followed by Cu 3.913 mg kg−1, Zn 3.611 mg kg−1, Ni 2.185 mg kg−1, Cd 0.458 mg kg−1, and Cr 0.446 mg kg−1. In the highly polluted sector, mean concentration of Cu 9.665 mg kg−1 was followed by Pb 8.861 mg kg −1 , Zn 5.796 mg kg −1 , Ni 4.468 mg kg − 1 , Cr 1.206 mg kg − 1 , and Cd 0.575 mg kg−1. The order of distribution of AB-DTPA extractable metals in soil of the study area is Pb>Zn> Cu>Ni>Cd>Cr for CS, Pb>Cu>Zn>Ni>Cd>Cr for LPS, and Cu>Pb>Zn>Ni>Cr>Cd for the HPS. The findings indicate that the orders of distribution for extractable concentration of selected toxic heavy metals in the three sectors are quite different. In case of LPS, Pb comes first in distribution order and Cu is second one while in HPS Cu come first and Pb is the second one.
The extractable concentrations of Pb and Cr in the present study were lower than the soil irrigated with fresh canal water and wastewater of Hyderabad City in southern Pakistan (Jamali et al. 2007). The data revealed that concentration range of Pb and Cu observed in our study area was also lower than those reported for soil irrigated with wastewater in suburban areas of Varanasi, India (Sharma et al. 1996). Elemental analysis of total metal concentration in soil The predominant heavy metals in the CS soil irrigated with tube well water were Pb, Ni, and Cu. The highest mean concentration of Pb 21.038 mg kg−1 was followed by Ni 10.465 mg kg −1, Cu 10.311 mg kg−1 , Zn 8.210 mg kg−1 , Cr 7.718 mg kg−1, and then Cd 2.621 mg kg−1 (Table 6). In the less polluted area, mean concentration of Zn 47.300 mg kg−1 was followed by Pb 43.233 mg kg−1, Cu 38.483 mg kg−1, Ni 32.566 mg kg −1 , Cr 22.283 mg kg −1 , and Cd 7.915 mg kg−1. In highly polluted area, the mean
Table 7 Descriptive statistics of toxic heavy metal concentration levels (mg kg−1) in cabbages of selected sectors of Peshawar HPS
LPS
CS
M
Min
Max
Mn±SD
SW
Min
Max
Mn±SD
SW
Min
Max
Mn±SD
SW
Pb
1.46
2.71
2.14±0.54
−0.34
1.21
1.62
1.43±0.14
−0.23
0.45
0.73
0.59±0.11
−0.18
Cr
0.58
1.24
0.86±0.27
0.71
.12
0.91
0.47±0.27
0.50
0.13
0.27
0.19±0.05
0.13
Cd
1.70
5.10
2.92±1.25
1.12
1.64
2.81
2.25±0.42
−0.17
0.73
1.05
0.90±0.11
−0.30
Cu
1.90
3.70
2.65±0.76
0.77
1.40
6.20
3.23±1.62
1.35
2.20
3.70
2.97±0.57
−0.31
Zn
28.60
34.90
31.82±2.69
0.12
25.50
31.40
28.88±2.26
−0.48
16.90
18.80
17.78±0.70
0.26
Ni
3.50
5.60
4.45±0.79
0.29
1.60
4.50
3.23±1.04
−0.64
1.10
3.70
2.55±1.06
−0.59
M metals, Max maximum, Min minimum, Mn mean, SW skewness, HPS highly polluted sector, LPS less polluted sector, CS control sector
Author's personal copy 126 Page 8 of 12
concentration of Zn 55.200 mg kg−1 was followed by Cu 48.350 mg kg − 1 , Pb 43.783 mg kg − 1 , Ni 41.533 mg kg −1 , Cr 34.083 mg kg −1 , and Cd 9.100 mg kg−1. The order of distribution of selected toxic heavy metals in soil of CS is Pb>Ni>Cu>Zn> Cr>Cd; in LPS, it is Zn>Pb>Cu>Ni>Cr>Cd, and in HPS, Zn>Cu>Pb>Ni>Cr>Cd. The results indicate that the total concentration of selected toxic heavy metals in soil has different distribution orders in the three sectors. Industrial sources of heavy metals in Peshawar may include sugar manufacture and leather tanning, which are the oldest industries in Pakistan. These are potential sources of heavy metal contamination of water, soil, and crops, particularly vegetables and fodder (Mussarat et al. 2007). Different fertilizers such as urea, triple super phosphate, and potassium applied to crops in the fields irrigated with sewage water in LPS and HPS may have contributed to the metal contamination of soil.
Environ Monit Assess (2015) 187: 126
heavy metals like Pb, Cd, and Zn in cabbage grown in HPS exceeds the permissible limits of FAO/WHO (2001) and SEPA (2005). Student/Tukey’s test for comparison of mean concentration levels In the sewage-contaminated water of the studied sectors (LPS and HPS), the concentrations of some of the toxic heavy metals like Pb, Cd, Cu, Zn, and Ni differ significantly at PCu>Ni>Cd>Pb>Cr for LPS and Zn>Ni>Cd> Cu>Pb>Cr for HPS. The results indicate that the order of distribution for concentration of selected toxic heavy metals in cabbage of the three sectors was different. The concentration of all the toxic heavy metals observed in cabbage of the study area was lower than those reported in spinach (Spinacia oleracea L.) grown on soil irrigated with wastewater in suburban areas of Peshawar, Pakistan (Ullah et al. 2012). The concentration of toxic
Concentration in sewage water of HPS
1.038 1.225
12.051
0.015
13.735
0.023
Zn
Ni
0.386
0.064
0.430
0.577
0.082
0.649
Unpaired t- test for means in LPS and HPS *
ns
**
*
*
**
Extractable concentration in soil of LPS 7.010
0.446
0.458
3.913
3.611
2.185
5.796
4.468
Extractable concentration in soil of HPS 8.861
1.206
0.575
9.665
Unpaired t test for means extractable in LPS and HPS *
*
ns
**
*
**
Total concentration in soil of LPS 43.233
22.283
7.915
38.483
47.300
32.566
48.350
55.200
41.533
Total concentration in soil of HPS 43.783
34.083
9.100
Unpaired t test for means extractable concentration in soil of sector LPS and HPS ns
**
ns
**
*
*
Concentration in cabbages of LPS 1.426
0.473
2.255
3.233
28.883
3.233
2.916
2.650
31.816
4.450
Concentration in soil of HPS 2.136
0.858
Unpaired t test for means concentration in sectors LP versus HP **
ns
ns
ns
ns
ns
ns non-significant, HPS highly polluted sector, LPS less polluted sector *P
