Impact of Burning E-waste on Soil Physicochemical Properties and Soil Microorganisms

Abstract

Aims: To investigate the impact of burning e-waste on soil physical, chemical and microbiological properties at sub-surface. Study Design: Soil samples from six different spots were collected at a depth of 0–6 cm from e-waste dumpsite where e-waste are burnt to disposed them. The samples were then mixed together to give a general view of the impact of burning the e-waste on the dumpsite soil. The soil sample was then subjected to physicochemical and microbiological analyses. This was repeated for soil without e-waste. Place and Duration of Study: Soil samples were collected from e-waste dumpsite Alaba International Market, Lagos State, Nigeria. Methodology: The organic carbon and organic matter were determined using gravimetric techniques, nitrogen was determined using kjeldhal methods, exchangeable bases were determined using flame emission spectrometry and EDTA classical methods titration, heavy metals determination in soil samples were estimated using atomic absorption spectrometer (ASS) and the microbiological analyses were carried out using standard methods. Results: Burning of e-waste increased the moisture content, organic matter, organic carbon, organic nitrogen, exchangeable bases (with the exception of calcium and sodium) and all the heavy metals assessed as compared to soil without e-waste. The concentration of the heavy metals in e-waste soil is Pb>Zn>Mn>Ni>Co>Cr>Cd while the concentration in soil without e-waste is Zn>Pb>Mn>Cr>Ni>Co>Cd. However, decreased were observed in the pH and organic phosphorus of the e-waste soil. Furthermore, eight microorganisms were isolated from soil of e-waste dumpsite where e-waste is burnt while five microorganisms were isolated from soil without e-waste. The bacterial population ranged from 1.68x107–1.92x107 cfu/ml while the fungi population ranged from 1.0x105–2.0x105 sfu/ml. The genera of microorganisms isolated were; Bacillus, Proteus, Enterobacter, Staphylococcus, Candida, Zoopage, Articulospora and Varicosporium. Conclusion: The formation of substances such as ash and charred matter due to burning might improve soil properties. On the other hand the burning leads to increase in the soil’s heavy metals, which might become toxic to organisms in the soil if their permissible level is surpassed. This causes environmental pollution and therefore it is useful to study the impact of e-waste burning on soil properties. Moreover, it is important to consider a recycling strategy in order to protect the soil and its living organisms from harsh process of burning e-waste.