4.7 Spatial Distribution of Various Indices
4.7.2 Enrichment Factor
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Figure 4.56: Spatial distribution of CF of Sb in (a) dry season and (b) rainy season.
From the above articles, it is sure that all the metal elements considered in the distribution study of CF had a greater magnitude in the soil of the studied waste disposal site during dry season than rainy season. In case of most of the elements considered here, the distribution pattern for CF was quite uniform in both seasons. Though the two seasonal CF distribution patterns for different metals do not cover the same geometric area, but it is clear that the range of magnitude was decrease along increasing distance from the centre point of the waste disposal site. This reduction of this index was 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.
116 4.7.2.1 Iron
The spatial distribution of EF for the metal elements Fe in soil (forty soil samples) for dry and rainy season is presented in Figure 4.57(a) and Figure 4.57(b), respectively. In dry season, the maximum range EF is 7.07 to 7.56 which indicates moderately severe enrichment in the soil. But the most of the area lies in the class of moderate enrichment (EF = 3 to 5) according to EF ranges. On the other hand, the maximum EF range for Fe is 2.383 to 2.437 close to the centre point of the disposal site which indicates minor enrichment. Comparing the both seasons EF for Fe, the enrichment grade is low in rainy season than dry season.
Figure 4.57: Spatial distribution of EF for Fe during (a) dry season and (b) rainy season.
4.7.2.2 Manganese
Figure 4.58(a) and Figure 4.58(b) depicted the spatial distribution of EF for Mn in soil for dry season and rainy season respectively. In both seasons, most of the sampling site lies in the class of minor enrichment (EF = 1 to 3) according to EF ranges. The maximum range of this index for Mn in dry season was 6.68 to 7.34 and 3.06 to 3.36 during rainy season.
Therefore, there was reducing discrepancy in EF due to the change of dry to rainy season.
(a) (b)
(a) (b)
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Figure 4.58: Spatial distribution of EF for Mn during (a) dry season and (b) rainy season.
4.7.2.3 Chromium
Figure 4.59(a) and Figure 4.59(b) illustrate, metal enrichment maps plotted EF distribution for Cr during dry and rainy season respectively. In dry season, the maximum range EF is 20.49 to 22.33 which indicates severe enrichment in the soil for Cr where reference element is Al. Moreover, the area undergoes moderately severe enrichment to severe enrichment in dry season. On the other hand, the maximum EF range for Cr is 12.196 to 13.159 in rainy season but most of the area lies in the class of moderately severe enrichment. Analysing the figures it is sure the enrichment status was found slight in dry season compared to dry season.
Figure 4.59: Spatial distribution of EF for Cr during (a) dry season and (b) rainy season.
4.7.2.4 Lead
Figure 4.60(a) and Figure 4.60(b) illustrate, metal enrichment maps plotted EF distribution for Pb during dry and rainy season respectively. In dry season, the maximum range EF is 556.99 to 600.23 which indicates extremely severe enrichment in the soil for Pb where reference element is Al. On the other hand, the maximum EF range for Pb is 432.37 to 458.41 in rainy. Analysing the figures it is sure the enrichment value ranges was found less in rainy season compared to dry season. But, the total sampling area shows extremely sever enrichment for this metal in both seasons.
(a) (b)
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Figure 4.60: Spatial distribution of EF for Pb during (a) dry season and (b) rainy season.
4.7.2.5 Cadmium
The spatial distribution of EF for the metal elements Cd in soil for dry season and rainy season is demonstrated in Figure 4.61 (a) and Figure 4.61 (b), respectively. In dry season, the maximum range EF is 9217.91 to 10043 which indicates extremely severe enrichment in the soil. Besides, the maximum range EF is 4244.13 to 4437.69 which also directs to extremely severe enrichment for Cd during rainy season. Moreover, all the area lies in the extremely severe enrichment (EF > 50) according to EF ranges in both seasons.
Figure 4.61: Spatial distribution of EF for Cd during (a) dry season and (b) rainy season.
4.7.2.6 Arsenic
Figure 4.62(a) and Figure 4.62(b) demonstrate metal enrichment maps plotted EF distribution for As during dry and rainy season respectively. In dry season, the maximum range EF is 441.95 to 456.17 which indicates extremely severe enrichment in the soil for As where reference element is Al. Similarly, during rainy season the maximum EF range for As
(a) (b)
(a) (b)
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is 381.22 to 406.96 indicating extremely severe enrichment .Analysing the figures it is sure the enrichment value ranges was found less in rainy season compared to dry season. But, the total sampling area shows extremely sever enrichment for this metal in both seasons.
Figure 4.62: Spatial distribution of EF for As during (a) dry season and (b) rainy season.
4.7.2.7 Mercury
Figure 4.63(a) and Figure 4.63(b) show EF distribution for Hg in dry season and rainy season respectively. The maximum ranges of EF in dry and rainy season were 124.08 to 134.2 and 78.33 to 83.06, respectively, thus indicated extremely severe enrichment (EF > 50). On the other hand, the minimum EF ranges for Hg were found to be very similar in magnitude (43.03-53.16 in dry and 40.34-45-08 in rainy season). Hence, the total sampling area shows extremely sever enrichment to very sever enrichment for this metal in both seasons.
Figure 4.63: Spatial distribution of EF for Hg during (a) dry season and (b) rainy season.
4.7.2.8 Antimony
(a) (b)
(a) (b)
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Figure 4.64(a) and Figure 4.64(b) illustrate, metal enrichment maps plotted EF distribution for Sb during dry and rainy season respectively. In dry season, the maximum range EF was 7226.93 to 7592.73 which indicated extremely severe enrichment in the soil for Sb where reference element is Al. Similarly, the maximum EF range for Sb was 6235.14 to 6610.38 in rainy season but most of the area lied in the class of moderately severe enrichment class.
Analysing the figures it is sure the enrichment status was found slight less in rainy season compared to dry season.
Figure 4.64: Spatial distribution of EF for Sb during (a) dry season and (b) rainy season.
From the above articles, it is sure that EF of all the metal elements had irregular shape of distribution patterns. Because all EF values are calculated using a reference element, Al.
This index value depends on the concentration of the metal, the Al concentration of the certain sampling point as well as the background values of Al and the certain element.
Moreover, distribution patterns are formed by the point concentration of different boreholes.
Thus, these distribution patterns are not same uniform for this index. From the distribution figures, the change of EF values with distance from the central point was not uniform, but it is clear that the maximum range of EF values were greater in the soil of the studied waste disposal site during dry season than rainy season. 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.