*Distribution of Potentially Toxic Elements in Water, Sediment and Soils in the Riparian… DOI: http://dx.doi.org/10.5772/intechopen.102440*


#### **Table 5.**

*Chemical characteristics and metal concentration in the Kraft pulp and paper mill solid waste.*


#### **Table 6.**

*Amount of leachable metals in soils and sediments near the pulp and paper industry.*


*No data reported for the precipitation of Cd as carbonate.*

*a Values from [50].*

*b Values from [51].*

#### **Table 7.**

*Solubility product constants between the theoretical values and experimental values.*

#### **Figure 3.**

*Variations in concentration of potentially toxic elements in water, sediment and soils along the three sampling sites in PanPaper, Webuye during the study period. One way-ANOVA test for potentially toxic elements concentrations at WIP, EDP and DSP showed significant differences denoted by different letters 'a', 'b' and 'c'. For each sets where columns had the same letter 'b' or 'a', the difference was not statistically significant.*

The leaching tests yielded only small amounts of Pb, Cd, Cu and Zn (**Table 6**). Statistical analysis confirmed that treatment with the different types and dosages of pulp and paper industrial wastes had an effect on the leaching behavior of these PTEs. However, treatments with 80 and 110 g L<sup>1</sup> of lime mud did not yield any statistical difference for Cu concentration (p = 0.124) and Cd (p = 0.432) (**Table 7**). Compared to the local standards, only the leaching of chromium and lead was within the regulatory limits.

The results of PTEs concentration in water at the WIP, EDP and DSP are presented in **Figure 3**. In this graph, the concentrations of PTEs in the soil were consolidated (8 values for each sampling point) and a mean concentration was calculated at WIP, EDP and DSP. In water, all the PTEs exhibited highest concentration at EDP but the difference in Cu concentration between ESP and DSP was not statistically significant. For soil samples, Pb, Cu and Zn remained higher at EDP, while Cd and Cu exhibited higher concentration at DSP, although the difference of Cd level between WIP and DSP was not statistically significant (p > 0.05).

PTEs distributions from the river, with respect to the paper mill are represented in **Figures 2**, **4**, and **5**. In **Figure 4**, at WIP, concentrations of Zn, Cu and Cd significantly (p < 0.05) reduced away from the river as one approached the factory (AA side), while Pb increased. On the BB side at WIP, Pb, Cd and Cu concentrations also decreased significantly (p < 0.05) away from the river, while Zn reduced (**Figure 4**). *Distribution of Potentially Toxic Elements in Water, Sediment and Soils in the Riparian… DOI: http://dx.doi.org/10.5772/intechopen.102440*

#### **Figure 4.**

*Trends of heavy metal concentration mg/g in wetland soil at WIP in PanPaper.*

In **Figure 2**, at EDP, all metals concentrations decreased (p < 0.05) away from the river as one moved closer to the factory (AA), while on the side opposite the factory away from the river, concentrations of Zn and Pb increased significantly as there was a marked reduction in Cu and Cd levels (BB side). Finally, at DSP (**Figure 5**), only Zn and Cu reduced away from the river bank to the factory, on the AA side, with an increase in Pb (p < 0.05). On the side BB, Pb, Cu, and Zn concentrations reduced away from the river (p < 0.05). Cd exhibited the same trend on both side of the river, with an initial increase followed by a slight and steady decrease as you moved away from the river.

The results of principal component analysis (PCA) on PTEs at 0 km, 0.5 km, 1 km, 1.5 km and 2.0 km on both sides (AA and BB) in the sediments, soil and water are

#### **Figure 5.**

*Trends of heavy metal concentration mg/g in wetland soil at DSP in PanPaper.*

presented in **Figures 6**–**10**. At 0 km from the river, two Principal Components (PC) could explain 96% of the variation in the data. There was a high positive score of Cd and Pb at EDP on AA side and high positive score of Zn and Cu at the DSP on both AA and BB sides. Generally, high score values were associated with the AA side at the EDP on the first PC (73.34%) but no clear association between PTEs concentration in soil, sediment and water. On the second PC (23.25%), there was a high positive score of Cd and Pb at the EDP but a high negative score of Zn and Cu at DSP at both AA and BB side (**Figure 8**).

In **Figure 7**, at 0.5 km from the river, two Principal Components could explain 93.26% of the variations in the data. There was a high positive score of Pb at the WIP on AA side and high positive score of Cd at EDP on BB side on PC1. A high positive score of Zn and Cu was recorded at DSP on BB side. Generally, high values were associated with the AA side at both EDP and DSP on the first PC (75.50%) but with no *Distribution of Potentially Toxic Elements in Water, Sediment and Soils in the Riparian… DOI: http://dx.doi.org/10.5772/intechopen.102440*

#### **Figure 6.**

*Principal component analysis of potentially toxic elements (Cd, Pb, Zn and Cu) sampled in sediments, water and at 0 km (both sides 0 km of the buffer zone at Webuye, PanPaper mill. sample location at WIP, EDP, DSP.*

#### **Figure 7.**

*Principal component analysis of potentially toxic elements (cadmium, Lead, zinc and copper) sampled in sediments, water and at 0.5 km (both sides of the buffer zone at Webuye, PanPaper mill. sample location at WIP, EDP, and DSP.*

clear association between PTEs concentration in the soil sediments and water. PC2 explained 17.78% of the total variability, and there was a high positive score of Cd at EDP and Pb at WIP on BB and AA sides respectively. There was a high negative score of Zn and Cu at DSP on BB side (**Figure 7**).

#### **Figure 8.**

*Principal component analysis of potentially toxic elements (cadmium, Lead, zinc and copper) sampled in sediments, water and at 1 km (both sides of the buffer zone at Webuye pan-paper industry. Sample location at WIP, EDP and DSP.*

#### **Figure 9***.*

*Principal component analysis of potentially toxic elements (cadmium, Lead, zinc and copper) sampled in sediments, water and at 2 km (both sides of the buffer zone at Webuye pan-paper industry. Sample location at WIP, EDP, DSP.*

*Distribution of Potentially Toxic Elements in Water, Sediment and Soils in the Riparian… DOI: http://dx.doi.org/10.5772/intechopen.102440*

In **Figure 8**, at 1 km from the river bank, there was a high loading of Cu on PC1 at WIP, Zn at DSP and Pb at EDP, all on the BB side, and high positive score of Cd at WIP on AA side. Generally, high scores were associated with AA side on PC1 (54.92%). On PC2 (21.34%), there was high positive loading of Cu at WIP on BB side and negative but weak loading of Cd at WIP on AA side. PC1 and PC2 explained up to 76% of the variability in the data.

In **Figures 9** and **11**, at 1.5 km and 2.0 km from the river bank, the concentrations of Pb and Cd had a high positive loading at WIP on the AA side. There was equally high positive score of both Cu and Zn, but they were not associated with any particular sampling points nor sides. At both distances (1.5 km and 2.0 km), there was a general strong influence of DSP and EDP on side AA and BB respectively on the PTEs loading from the river bank. The concentrations of PTEs followed a pattern similar to the one in **Figure 8** where Cu > Zn > Pb > Cd. However the concentration of Cu was higher on the side (AA) of the factory at DSP and EDP. While Zn and Cd levels were higher on the opposite side of the factory. The concentration of PTEs in sediment and water remain lower. The PCA1 and PCA2 could explain 73.4% of the observed variation in these measurements. WIP recorded the lowest concentrations of the PTEs at all the sampling points and on both sides (AA and BB) of the paper mill.

**Figure 10** described the Principle Component Analysis of variation of HMs between PTEs concentrations at EDP with pH, Temperature and electrical conductivity as secondary variables. The results show that Zn had relatively high positive score at EDP in relation to the pH, temperature and electrical conductivity on the first axis (56.75%). Pb had a high negative loading at WIP. Cu had a high negative score at DSP but was not associated with any environmental variable. On the second axis, Cd had a high positive score at WIP but was also not associated with any environmental variable. The second axis could only explain 26.53% of the total variability.

**Figure 10.** *Relationship between pH, EC and Temperature and Zn concentration at the EDP.*

#### **Figure 11.**

*Principal Component Analysis of potentially toxic elements (Cadmium, Lead, Zinc and Copper) sampled in sediments, water and at 2 km (both sides of the buffer zone at Webuye pan-paper industry. Sample location at WIP, EDP and DSP.*
