Analysis of Heavy Metals Mercury, Arsenic, Cadmium, Lead, Chromium, and Nickel in Waste Currency Dumpsite and its Environmental Implications

Abstract

Analysis of mercury, arsenic, cadmium, lead, chromium and nickel in soils and food crops (Cassava tuber and plantain fruits) within and around Nigeria waste currency dumpsite have been carried out using Atomic Absorption Spectrometry (AAS) Unicam Modern 969 Series with air acetylene flame with aim to determine the level of concentration, source(s) and level of pollution by comparing with established standards. The study area is located within Oluku on 60 27’ 4.4’’ N and 005035’ 53.5’’ E in Ovia North East Local Government Area in Edo State, Niger Delta, Nigeria. A total of 24 samples were collected from field; 12 soil samples, 11 from within and around the currency waste dumpsite at a depth of 0-15cm topsoil (TS) and 15-30cm subsoil (SS) with the aid of a hand auger while, 1 soil sample was taken from Iguosa at a distance of 1000m (1km) away from the dumpsite as a control. The food crops (Cassava tuber and Plantain fruits) 5 each were taken from the farms around the dumpsite 20 m away from the center of the dumpsite while, 1 each of the food crops were taken at a distance of 1000 m away. The analytical results were further subjected to statistical treatment at P < 0.05 percentage confidence level using SPSS. The results obtained were presented in a table as Mean ± SD, this shows that there was a significant decrease from topsoil (TS) to subsoil (SS) within and away from the dumpsite, while, the results obtained from the food crops show a similar trend. Cadmium was found to be higher than the permissible limit of 3 mg kg-1 soil while, other heavy metal were below the require limits. The concentration of the heavy metal in food crops were higher compared to the require standard for food crops. The ultimate results show that the concentration of the heavy metals analyzed in soil and food crops were from anthropogenic source which could be attributed to the dumping and burning of Nigeria currency note in the area. The high concentration of food crops could expose human to health risk through direct or indirect consumption of the food crops from the site. Consequently, the dumping and burning of waste currency by the apex bank in Nigeria should be discontinued while alternative method for burning of waste currency should be adopted.