Assessment of Heavy Metal Pollution in Soil and Surface Water in Mng-Gold, Kokoya District, Bong County, Liberia

Abstract

The presence of heavy metals in water and soil by metalliferous mining activities at MNG-Gold Mine was fully investigated. The extraction of gold in recent years, has led to the generation of huge quantities of solid and liquid wastes. During the course of the investigation, fourteen samples including surface water, groundwater and soil were collected and analyzed to determine physio-chemical parameters and heavy metal contents. Atomic Absorption spectrometer (AAS FS 240) was used to analyze iron (Fe), zinc (Zn), nickel (Ni), manganese (Mn) and lead (Pb) in samples from Adana, old TSF, new TSF and St. John River. Garmin 60 GPS was used during the field exercise to determine the coordinate points. The fourteen samples collected from water, soil and underground water were stored in 250 ml polyethylene bottle and kept at 19 0 C before analysis was conducted. The findings revealed that the iron concentration in water and soil at certain places was extremely high as compared to other metals. Out of 14 samples analyzed, five heavy metals such as Fe, Zn, Ni, Mn and Pb were detected in water at Adana, old TSF, new TSF and St. John River. The concentrations range from < 0.01 to 1.58, < 0.02 to 0.02, < 0.01 to 0.03, < 0.01 to 0.08 and < 0.01 to 0.02 ppm. Also, Fe, Zn, Ni, Mn and Pb were detected in sediment samples at Adana, old TSF, new TSF, Saprolite and St. John River and the concentrations range from 50,000-120,000 ppm, 15-55 ppm, 10-200 ppm, 50- 1000 ppm and 5-20 ppm respectively. Except for iron, all the other metals were below the WHO maximum thresholds.