**3.1 PTEs concentrations in soils**

**Table 1** reports on the 6 PTEs (Cr, Cu, Fe, Pb, Mn, and Zn) concentrations in 45 genuinely crude oil-contaminated soil samples collected from three petroleum hydrocarbon-contaminated sites in the Niger Delta, Nigeria. Summary statistics of the 6 PTEs concentrations for all the three study sites range as follows: Cr ranged from 54 to 75, Cu (5.4–16.6), Fe (14841–23,404), Pb (13.5–21.4), Mn (158–555), Zn (32.6–47.2)


**Table 1.** *Potentially toxic elements concentrations (mg/kg) in soils collected from three oil spill sites in the Niger Delta, Nigeria.*



*Perspective Chapter: Rapid Measurement of Potentially Toxic Elements (PTEs) in Petroleum... DOI: http://dx.doi.org/10.5772/intechopen.108959*

in Site 1; Cr (35–66), Cu (5–16.1), Fe (10166–20,967), Pb (12–17.8), Mn (209–440), Zn (17.6–33.6) in Site 2; in Site 3, Cr (32–115), Cu (6.5–20.8), Fe (7538–22,800), Pb (12– 135), Mn (98–338), Zn (19.9–177). As it can be seen, the trend of heavy metal contamination in the three sites is in the order: Fe > Mn > Cr > Zn > Pb > Cu. Fe contamination level was found to be the highest in site 1. Results (mean values) were compared with other studies [7, 28] conducted in the Niger Delta, Nigeria, the case study area of the current research. Except Fe that had no records at the moment to be compared with, most of the metal values were higher than those reported by [7, 28]. Also, the mean concentrations of Mn, Cr, Cu, Zn, and Pb were observed to be higher than the background concentrations reported by [29]. These results are presented in **Table 2**. Results show that crude oil spill is the source of PTEs pollution in the study sites.

### **4. Conclusions**

This chapter presents a portable XRF Analyser (Olympus, USA) as a rapid measurement tool (RMT) for PTEs (Cr, Cu, Fe, Pb, Mn, and Zn) in crude oil-contaminated soils. A total of 45 field samples collected from three genuinely PHC released sites in the Niger Delta, Nigeria were analyzed. The trend of PTEs contamination across the three sites follows the same order: Fe > Mn > Cr > Zn > Pb > Cu. While the mean values of some PTEs obtained in this study (sites 1 and 2) ranked higher than those reported in previous studies; the mean values of all the PTEs in Site 3 were higher than all the previously published results in the region. Consequently, results conclude that crude oil spills on land sites contributed to the higher concentrations of the PTEs relative to the natural background values. Since PTEs are bioaccumulants, they may pose a threat to environment and human well-being. Thus, there is research need to assess the site-specific risks of PTEs contamination in both the areas where soils are potentially polluted, and sites that have recorded series of oil spill incidents in the Niger Delta, Nigeria. Furthermore, the following recommendations are made:

