4.4 Variation of Metal Content in Soil
4.4.1 Iron
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concentrations of Cd in both the dry and rainy season were found within the standard range provided by WHO and maximum allowable limit of Austria and Canada (Table 4.4).
However, from Table 4.4 and Figure 4.4 it was observed that the mean concentration of Cd in soil for dry and rainy season exceed the maximum allowable limit, 0.3 mg/kg of USA and 1.4 mg/kg of CCME. In this study, the value of Cd in soil for dry season only goes over maximum allowable limit of metals in soil of Poland and UK.
The concentration of Pb and Cd can easily accumulate in the bodies of soil organisms. In fact, they are particularly very dangerous chemical, as they can accumulate in individual organisms, but also in entire food chains (Singh et al., 2011). Moreover, soil functions are disturbed by Pb and Cd intervention, where extreme concentrations are present.
Toxicological effects of Pb and Cd on soil microbes lead to the decrease of their numbers and activities though it depend largely on the type and concentration of metal and incubation time (Khan et al., 2010). The main sources of Pb and Cd in municipal solid waste are lead- acid batteries, household batteries, consumer electronics, glass and ceramics, plastics, soldered cans Pigments etc. (Korzun and Heck, 1990). The value of Pb is one out of four metals that have the most damaging effects on human health like anaemia, high blood pressure, kidney damage, brain damage, etc.
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Figure 4.5. In the early stage, the magnitudes of Fe were found to be higher and then it comparatively dropped until the end of the dry and rainy seasons (Figure 4.5). The Figure 4.5 reveals the concentration of Fe decreases in relation to the increasing of soil sampling distances for both the dry and rainy season. Here, it can be noted that the soil sample in case of dry season showed comparatively the higher values of Fe concentration than that of rainy season for the infiltration and dilution of metal content in rain water. This statement was also supported by Yahaya et al. (2009) and Rahman et al. (2012). Moreover, the concentration of Fe was found to be approximately 2.5, 5.0 and 6.0 times higher in dry season than that of rainy season for the sampling distances of 30, 180 and 300m, respectively. Based on the experimental results, it can be concluded that the magnitude of Fe concentrations during dry season were combatively higher than that of rainy season.
Figure 4.5: Spatial and seasonal variation of Fe concentration in soil.
The comparison of Fe concentration in soil for dry and rainy season in the present study with other researchers for similar cases is shown in Figure 4.6 and Figure 4.7, respectively. A study conducted by Yahaya et al. (2009) in Enugu landfill of Nigeria and presented the distribution of Fe in soil in both seasons and it was showing a similar pattern as reported in this study but showed a higher concentration during dry season. In dry season, distribution of Fe reported by Rahman et al. (2012) in case of Dhaka EPZ area had also a steady decrease in Fe concentration with distance as like the present study but the concentration range was excessive compared to the present study. However, distribution pattern of Fe concentration
0 500 1000 1500 2000 2500
30 60 90 120 150 180 210 240 270 300
Fe concentration (mg/kg)
Soil sampling distance from centre of disposal site (m)
Dry season Rainy season
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during rainy season was found to be the different because of having a dramatic fall in Fe concentration in 110 to 150 m.
Figure 4.6: Comparison of Fe concentration in soil during dry season with other researchers for similar cases.
Figure 4.7: Comparison of Fe concentration in soil during rainy season with other researchers for similar cases.
0 5000 10000 15000 20000 25000 30000 35000
0 50 100 150 200 250 300
Fe concentration (mg/kg)
Distance of soil sampling points (m)
Present study Rahman et al. (2012) Yahaya et al. (2009)
0 5000 10000 15000 20000
30 80 130 180 230 280
Fe concentration (mg/kg)
Distance of soil sampling points (m)
Present study Rahman et al. (2012) Yahaya et al. (2009)
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The variation of Mn concentration in soil, respect to soil sampling distances from approximately the central point of waste disposal site during dry season and rainy season are shown in Figure 4.8. Figure 4.8, respectively. The figures reveal that the concentration of Mn displayed dramatic rise and fall in spatial distribution for dry season, while steady decrease occurred during rainy season. Moreover, the concentration of Mn was found to be approximately 2.5, 4.0 and 11.5 times higher in dry season than that of rainy season for the sampling distances of 30, 180 and 300m, respectively.
Figure 4.8: Spatial and seasonal variation of Mn concentration in soil.
The comparison among present study and similar studies of other researchers based on Mn concentration in soil for both the dry and rainy season is illustrated in Figure 4.9 and Figure 4.10, respectively. Here, the concentration of Mn was relatively lower in present study than the reported values by Rahman et al., (2012) and Yahaya et al. (2009). Moreover, the distribution pattern of the Mn was steadier in both seasons than the distribution patterns for the same seasons represented by Rahman et al., (2012) and Yahaya et al. (2009).
0 5 10 15 20 25 30 35
30 60 90 120 150 180 210 240 270 300
Mn concentration (mg/kg)
Soil sampling distance from centre of disposal site (m)
Dry season Rainy season
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Figure 4.9: Comparison of Mn concentration in soil during dry season with other researchers for similar cases.
Figure 4.10: Comparison of Mn concentration in soil during rainy season with other researchers for similar cases.