Effects of Effluent on Cultivated Soil Properties in Kedjoum Ketinguh, Northwest Region of Cameroon

Abstract

This study assessed the physicochemical and heavy metal properties of cultivated soils contaminated by effluent and uncontaminated soils in Mphiewen-Kedjoum Ketinguh, Northwest region of Cameroon, in the rainy and dry seasons respectively. In addition, the physicochemical and heavy metals properties of effluent from Mphiewen, responsible for contamination of Mphiewen soil were assessed. We hypothesized that heavy metals from the effluent affected the cultivated soil and plants grown on it. All analyses were carried out on the soil and effluent samples using standard analytical methods. The results revealed that, the soil samples had pH values ranging from 5.9 to 6.0. The effluent sample had pH value of 5.9 and 6.9 in rainy and dry seasons respectively. The organic matter levels in the soils were high and ranged from 5.0-8.92% in both seasons. Total nitrogen content in all the soils were low (N < 1%) and ranged from 0.1 to 0.3%. C/N ratios were high (ranging from 15 to 17), indicating that the organic matter was inadequately mineralized. Heavy metals analysis showed that the cultivated soil was contaminated by cadmium with total concentration of 3.7 mg/kg in the dry season, and chromium with total concentrations of 100.05 and 105.49 mg/kg in rainy and dry seasons respectively. Pearson correlation between some physicochemical properties of the contaminated soil and effluent physicochemical properties were all unity (r = 1.000; p < 0.01). This indicated that the effluent from the dumpsite was the main source of contaminant in the cultivated soil receiving the effluent. The problem of Cd and Cr toxicity in the contaminated soil can be solved by using various methods based on physical, chemical, and biological processes such as chemical precipitation, membrane separation, ion exchange, electrodialysis, phytoremediation, and surface adsorption