**2. Material and methods**

### **2.1 The study area**

Ebocha-Obrikom is located among latitude 5°20 N–5°27 N as well as longitude 6°40 E–6°4 6E (**Figure 1**). It includes the towns of Obor, Obie, Obrikom, Agip New

#### **Figure 1.**

*Map showing the study area with Nigeria and River State insert. Sources: Adapted from Olalekan et al. [14].*

Base and Ebocha, all of which are positioned in Ogba/Egbema/Ndoni Area (**Figure 1**) of Rivers State. The research study area is bordered to the North by the Nkissa River, to the West by the Orashi River, to the East by the Sombrero River, and to the South by Omoku town [1, 2].

#### **2.2 Sample collection**

The current research inquiry used a sample method similar to that used by Morufu and Clinton [13], Raimi and Sabinus [12], and Olalekan et al. [14], in which sampling was targeted in selected vulnerable quarters in a highly populated environment. These areas are prone to pollution not just due to their physical location, but also due to the existence of crude petroleum exploration and exploitation. Water samples were taken from groundwater sources near the sampling location (see **Table 1** below) and used mostly for drinking and domestic purposes. Only groundwater from dug wells or shallow pumping wells built specifically for residential use was sampled. The wells range in depth from 10 to 28 meters, indicating that they are in a phreatic aquifer. Portable GPS devices were used to record the sampling locations. Ground water sources in the neighborhood of the depot were chosen at random but at varying distances from one another for the purposes of this experiment. Furthermore, samples were manually collected from nine (9) strategic locations in the study area for ground water (boreholes and wells) into previously washed clean plastic sampling bottles after approximately 20 min of continuous water flow to ensure adequate aquifer that can remain suitably represented.


**Table 1.**

*Geographical coordinates of the nine (9) sampling sites (samples).*

All samples were collected during the day, from 9:00 am to 4:00 pm. As a result of flooding, insecurity as well as lockdown from COVID-19. Night samples were not taken, and the sampling took place between the month of September 2019 and August 2020.
