EFFECT OF CADMIUM (Cd) POLLUTION ON MICROBIAL POPULATION AND ENZYME ACTIVITIES IN SOILS.

Godwin U. Apkan

ABSTRACT

Heavy metal contamination of soil occurs when heavy metal are introduced into the soil through human activities, leading to the gradual deterioration of the ecology and environment. The experiment to determine the effect of cadmium on microbial community and enzyme activities was carried out in the Department of Soil Science and land Resources Management, University of Uyo in 2022. Soil sample was collected from agricultural soil with unknown contamination history at the depth of 0 – 20 cm. The soil was contaminated with cadmium (Cd) using CdSO₄ solution at different application rates of (0, 150, 300, and 500mg, per 500gr soil). The amended soils (in pots) were incubated in the screen house with 60% of water holding capacity for 12 weeks. During the incubation period, samples were collected from each pot at 0, 2, 9, and 12 weeks for microbial and enzyme assays. The results showed that heavy metal (Cd) slightly inhibited bacterial and fungal populations in all the samples spiked with cadmium. Actinomycetes population was significantly inhibited by Cd. The extent of inhibition increased with increasing level of Cd concentrations, and varied with the incubation periods. Soil enzymatic activities in all the samples treated with Cd were also significantly inhibited. The level of inhibition increased significantly with increasing level of Cd concentration, and also varied with the incubation periods. Urease activity was heavily inhibited than cellulose activity.

Keynotes: Cadmium, Microbial Population Enzyme Activities