ABSTRACT
This study’s primary goal was to investigate heavy metal concentrations, radioactive emissions, physico-chemical and microbial compositions of polluted soil from three e-waste disposal locations. Electrronic waste soil samples were collected from Oluku and Osasogie in Benin, Edo State while the third electronic waste soil sample was obtained from Alaba, Lagos State, Nigeria. The microbial analysis was done based on standard microbiological methods. The Physico-chemical analysis of samples such as pH, moisture content, organic carbon, total nitrogen (N), available Phosphorus (P) and potassium concentration were done using a standard chemical techniques. The physicochemical properties across the e-waste sites, Oluku, Osasogie and Alaba, the available Phosphorus (19.04±0.147) and total Nitrogen (6.263±0.049) were highest at control. The mean bacterial counts on nutrient agar (NA) ranged between 9.0±2.6 cfu x 106 /g and 5.3±1.2 cfu x 106 /g, the former is for Oluku while the latter is for Osasogie respectively while the highest fungi counts was recorded in the control site (10.6±1.8 cfu x 104 /g) and the lowest count (3.3±0.9 cfu x 104 /g) was recorded at Alaba. The isolated bacteria and fungi include, Bacillus cereus, Bacillus subtilis, Clostridium botulinum, Pseudomonas aeruginosa, Yersinia enterocolitica Serratia marcescens, Klebsiella oxytoca, Providencia stuartii, Aspergillus niger, Geotrichum candidum, Rhizopus micosporus, and Penicillium chrisogenum. respectively. Alaba soil sample recorded the highest amount of all the heavy metals analyzed which include, Lead (Pb), Zinc (Zn), Cadmium (Cd), Nickel (Ni), Copper (Cu), Chromium (Cr), Manganese (Mn) and Iron (Fe). Cadmium (Cd) was the only heavy metal that was not detected (ND) for control soil sample. The electronic waste, example phone panels were grounded into fine granules and mixed with with 3 kg of composite soil, watered and allow to stay for 24 hours. Fluted pumpkin seeds were thenn planted and their growth were monitored for three weeks. Analysis was done on the leaves to assess the rate of heavy metal absorption by the fluted pumpkin. Heavy metal assimilated by fluted pumpkin (Telfairia occidentalis) ranges from Pb: 0.01±0.005. Zn: 0.001±0.02. Cd: 0.01±0.009. Ni: 0.001±0.015. Cu: 0.001±0.003. Cr: 0.001±0.103. Mn: 0.006±0.757. Fe: 0.001±0.066. (Mg/kg). These metals are amongst the metals referred to as common urban pollutants and are below the permissible limit for edible vegetables. The soil samples were prepared for radioactive analysis, it was packed in a plastic container and sealed with a tape and kept for 30 days in order to attain secular equilibrium between radium and its gaseous decay progenies then analyzed using gamma ray spectrometer. xiv There were significant differences in the activity concentrations of natural radionuclides (40K, 226Ra, 323Th) in all the soil samples. The highest mean values obtained for 226Ra and 323Th was in Alaba with (79.630±4.557, 30.177±1.83) respectively, The values obtained at Oluku and Osasogie e-waste dumpsite were lower than the world average values of 412 Bq/kg, 35 Bq/kg and 30 Bq/kg for 40K, 226Ra, and 232Th, respectively, but 232Th is at the recommended limit while 226Ra is above the average limit for Alaba e-waste site. The government should establish strict policies and procedures for handling, recycling and disposal of electronic waste and should involve taking precautions against the emission of radioactive materials. Electronic waste has demonstrated negative effects on microorganisms crucial for nutrient cycling, soil fertility and public health, especially in areas where e-waste recycling or disposal occurs without proper safeguards
