Contaminated Site Investigation using Nuclear Technique: A Case Study of Temporary Transformer Storage Sites in Ghana

Abstract

Recent introduction of man-made toxic chemicals, and the massive relocation of natural materials to different environmental compartments like soil, ground water and atmosphere, has resulted in severe pressure on the self-cleansing capacity of recipient ecosystems. Various accumulated pollutants and contaminants such as polychlorinated biphenyls (PCBs) are of much concern relative to both human and ecosystem exposure and potential health impact. PCBs which are resistant to degradation and bioremediation accumulate in different niches of the biosphere. This significantly affects ecological balance and cause adverse health effect on both human and the environment. Temporal transformer storage sites at four locations in Ghana (Tema, Tamale, Bolgatanga and Wa) were investigated for PCB contamination using nuclear techniques. Analysis of soil samples from four temporal transformer storage sites revealed that the soil samples from Tema, Tamale, Bolgatanga and Wa were generally sandy with pH and EC ranging between 6.24 - 7.29 and 44.60 – 188.30 respectively. The PCB levels detected in the soil samples from the various locations varied considerably with mean ranging between 7.69 and 51.92 mg/Kg. The highest mean PCB level was recorded at the Tema temporal transformer storage site (51.92 mg/Kg), while the least mean level of 7.69 mg/Kg was recorded at Wa storage site. At Tamale the individual levels ranged between 3.57 mg/Kg and 38.70 mg/Kg while at Bolgatanga it was 6.85 – 16.30 mg/Kg and Wa, 6.08 – 14.70 mg/Kg. About 9% of soil samples from temporal transformer storage sites analysed had total PCBs concentrations above the 25 mg/Kg and 33 mg/Kg level recommended by the Canadian Council of Ministers of environment (CCME) and EPA Ghana respectively for the protection of environment and human health. Generally, the levels of PCBs in soil samples were found to decrease with increasing depth at all the temporal transformer storage sites. Results obtained using the EPA’s L2000DX PCB/ Chloride Analyser and Instrumental Neutron Activation Analysis (INAA) to analyse extractable organochlorine from the soil samples indicated that the nuclear technique is a better analytical technique for contaminated site investigation due to its high sensitivity, selectivity, fast and non-destructive nature. The INAA and gamma spectroscopy using HPGe detector coupled with MAESTRO 32 software provided a fast and efficient way to analyse possible PCB contamination in the soil samples and therefore proved to be very reliable method that could be conveniently used for contaminated site investigation