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to the outer side area of the waste disposal site during both seasons. In addition, Fe concentration is higher in dry season than rainy season.
Figure 4.23: Spatial distribution of Fe concentration in soil for (a) dry and (b) rainy season.
4.5.2 Chromium
The surface spatial distributions of the concentration of Cr in soil for dry season and rainy season are presented in Figure 4.24 (a) and Figure 4.24 (b), respectively. The value of the concentration of Cr for soil sample from central point (approximately 0 m) ranges from 7.67 to 8.22 mg/kg, while, for soil sample from farthest point (390m from central point) ranges from 4.36 to 4.91 mg/kg for dry season. Moreover, Cr concentration ranges from 4.93 to 5.52 mg/kg for soil sample from near to centre (approximately 30 m) and 0.77-1.36 mg/kg for soil sample from farthest point (315m from central point) in rainy season. In figures, the deep blue colour indicated that the soil was highly contaminated with the high concentration of Cr in soil, while, the green with yellow colour indicated the soil was less contaminated with the concentration of Cr in soil of that sampling point was comparatively very low. Form figure, it is clear that the maximum concentration range in dry season not only covers the centre point of the disposal site but also the surrounding area of the site. The distribution patterns are similar in both season but the intensity of Cr is decreasing with lateral distance from the centre point of the area. The ranges of concentration in both season shows, the dry seasonal Cr concentration in soil was higher than rainy season.
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Figure 4.24: Spatial distribution of Cr concentration in soil for (a) dry and (b) rainy season.
4.5.3 Zinc
Figure 4.25(a) and Figure 4.25(b) illustrate the surface spatial distribution of the concentration of Zn in soil for dry season and rainy season respectively. In spatial distribution, the deep blue color indicated the concentration of Zn in soil of that sampling point was very high, while, the green with yellow color indicated the concentration of Zn in soil of that sampling point was comparatively very low. The magnitude of the concentration of Zn for soil sample from central point (approximately 0 m) ranges from 46 to 48 mg/kg, while, for soil sample from farthest point (390m from central point) ranges from 23 to 26 mg/kg for dry season. In addition, Zn ranges from 21.91 to 24.29 mg/kg for soil sample from near to center (approximately 30 m) and 11.82 -13.21 mg/kg for soil sample from farthest point (315m from central point) in rainy season. The distribution patterns are similar in both season but the intensity of Zn in soil was higher in dry season. In addition, the concentration of Zn was decreasing with lateral distance from the centre. point of the area.
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Figure 4.25: Spatial distribution of Zn concentration in soil for (a) dry and (b) rainy season.
4.5.4 Cadmium
Figure 4.26 (a) and Figure 4.26 (b) demonstrate the map containing surface spatial distribution of the concentration of Zn in soil for dry season and rainy season respectively.
The magnitude of the concentration of Cd for soil sample from central point (approximately 0 m) ranges from 6.50 to 6.99 mg/kg as well for soil sample from farthest point (390 m from central point) ranges from 2.55 to 3.04 mg/kg for dry season. Further, in rainy season, Cd concentration ranges from 3.41 to 2.72 mg/kg for soil sample from near to center (approximately 30 m) and 1.24 to 1.55 mg/kg for soil sample from farthest point (315 m from central point). Outcome of the distribution depicted that the concentration of metal elements decreases in relation to the increasing of soil sampling distances from approximately the central point of waste disposal site. Comparing seasonal concentration of Cd, dry seasonal Cd concentration was high.
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Figure 4.26: Spatial distribution of Cd concentration in soil for (a) dry and (b) rainy season.
4.5.5 Arsenic
The surface spatial distribution of the concentration of As in soil for dry and rainy season (twenty soil samples) is presented in Figure 4.27 (a) and Figure 4.27 (b), respectively. Here, the ranges of As concentration in dry season and rainy season were categorized in 9 and 8 classes respectively as well as distinguished by different shades of deep blue and green with yellow colors. The magnitude of the concentration of As for soil sample from central point (approximately 0 m) ranges from 7.94 to 8.74 mg/kg, while, for soil sample from farthest point (390 m from central point) ranges from 1 to 2 mg/kg for dry season. Besides, As ranges from 3.32 to 3.67 mg/kg for soil sample from near to center (approximately 30 m) and 0.87- 1.22 mg/kg for soil sample from farthest point (315 m from central point) in rainy season.
Thus, it is clear that the concentration of As was higher in soil of the center and decreases gradually to outer side soil of the disposal site. Figure also shows the range of As concentration was slightly greater in dry season than that of rainy season.
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Figure 4.27: Spatial distribution of As concentration in soil for (a) dry and (b) rainy season.
4.5.6 Mercury
The following figure (Figure 4.28(a) and Figure 4.28(b)) show the surface spatial distribution of Hg concentration in soil of the selected waste disposal site for dry season and rainy season, respectively. Here, the ranges of Hg concentration in both seasons distinguished by different shades of deep blue and green with yellow colors. Figure shows the magnitude of the concentration of Hg for soil sample from central point (approximately 0 m) ranges from 8 to 9 mg/kg, while, for soil sample from farthest point (390 m from central point) ranges from 1 to 2 mg/kg for dry season. Maximum of the total sampling site is covered concentration 2 to 4 mg/kg of Hg depicted by figure in dry season. Similarly, Cd ranges from 3.57 to 3.93 mg/kg for soil sample from near to center (approximately 30 m) and 0.85 -1.30 mg/kg for soil sample from farthest point (315 m from central point) in rainy season. In addition, not only the farthest point, the area slightly far from center had Hg concentration 0.85 -1.30 mg/kg also. The distribution pattern in dry season was irregular where in rainy season pattern shows uniform distribution along the area. From the figure it can be said that the extreme level of Hg was present in the soil of central point where it decreases along the lateral distance. Moreover, Dry season shows the high range of Hg concentration.
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Figure 4.28: Spatial distribution of Hg concentration in soil for (a) dry and (b) rainy season.
4.5.7 Titanium
The surface spatial distribution of the concentration of Ti in soil for dry and rainy season are offered in Figure 4.29(a) and Figure 4.29(b), respectively. The concentration of Ti for soil sample from central point (approximately 0 m) ranges from 1791 to 1935 mg/kg, while, for soil sample from farthest point (390 m from central point) ranges from 636 to 780 mg/kg for dry season. Besides, Ti ranges from 1308 to 1441 mg/kg for soil sample from near to center (approximately 30 m) and 244 to 377 mg/kg for soil sample from farthest point (315 m from central point) in rainy season.
Figure 4.29: Spatial distribution of Ti concentration in soil for (a) dry and (b) rainy season.
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The distribution patterns tell that concentration of metal is large in dry season than rainy season. Though the two seasonal distribution patterns does not cover the same geometric area, but it is clear from the figure that metal concentration is decrease along increasing distance from the center point of the waste disposal site.
4.5.8 Antimony
Figure 4.30(a) and Figure 4.30(b) represented the surface spatial distribution of the concentration of Sb in soil of waste disposal site during dry season and rainy season respectively. In figure, the deep blue color indicated the concentration of Sb in soil of that sampling point was very high, while, the green with yellow color indicated the concentration of Sb in soil of that sampling point was comparatively very low. The magnitude of the concentration of Sb for soil sample from central point (approximately 0 m) ranges from 11 to 12 mg/kg, and for soil sample from farthest point (390 m from central point) ranges from 2 to 3 mg/kg for dry season. In addition, Sb ranges from 5.54 to 6.11 mg/kg for soil sample from near to center (approximately 30 m) and 0.98 to 1.55 mg/kg for soil sample from farthest point (315 m from central point) in rainy season. Figure of distribution reveals that the concentration of Sb in soil collected from the central point of the waste disposal site showed higher magnitude than the others. Mainly, along the distances the Sb concentration decreases and during dry season the ranges was higher than rainy season.
Figure 4.30: Spatial distribution of Sb concentration in soil for (a) dry and (b) rainy season.
From the above articles, it is sure that all the metal elements considered in the study had a greater concentration in the soil of the studied waste disposal site during dry season than rainy season. Though the two seasonal distribution patterns do not cover the same geometric area, but it is clear that the concentration was decrease along increasing distance from the
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centre point of the waste disposal site. The reduction of concentration is caused by the effect of leaching by infiltrating water. Besides, during heavy rainfall, soluble metal content get diluted and runoff from the dumpsite spreads to the surrounding soil.