3.2.1. Geo-Accumulation Index (*Igeo*)

In this study, the values of *Igeo* recorded for heavy metal concentrations of sediment samples from the River Kaduna are presented in Table 3. Based on the classification by Muller [32], the recorded values of *Igeo* for Cd at sites S1 (−2.39) and S2 (−2.91) fell into class zero, which means the sediments in S1 and S2 were unpolluted by Cd. In contrast, all the sites were found to be extremely polluted with the other heavy metals with *Igeo* > 5 falling in class 6. However, site S4 *Igeo* (0.33) for Cd fell in class 1, and S3 (3.53) and S5 (3.56) fell in class 4 indicating unpolluted to moderate pollution, and strongly polluted respectively.


**Table 1.** Consensus-based sediment quality guideline values (mg/kg) for heavy metals in sediment and averages for metals concentration in sediments and *Bellamyaunicolor* sampledfromtheRiverKaduna.

Note: CSd = Concentration of heavy metals in sediment. CSn = Concentration of heavy metals in freshwater snail: *Bellamya unicolor*. TEL = Threshold effect level. PEL = Probable effectlevel, NA = Not available.




**Table 3.** Geoaccumulation (*Igeo*) values of heavy metals in sediments and their class.

Note: S = Site.
