Assessment of heavy metal contamination in soil and management of occupational wastes in automobile mechanic villages, Imo River basin Nigeria.

摘要

Automobile waste management may constitute this century's topmost environmental problem in developing countries. This is because mechanic villages (MVs) considered as the affordable capacity for motor vehicles, lack waste management plan and thereby causing serious environmental pollution. The result is ecological and public health risks. Spectroscopic analysis of heavy metal enrichment of soil within and around MVs was therefore conducted. Results show that the Okigwe, Orji and Nekede MV soils in the Imo River basin have moderate to excessive heavy metal pollution. Metal concentrations (mgkg-1) are above background levels in the topmost 100 cm of soil, varying between MVs. The range is 748 -70,606 for Fe; 99-1090 for Pb; 186-600 for Mn; 102-1001 for Cu, 8-23 for Cd, 4-27 for Cr, and 3-10 for Ni. Average metal dispersion rate (mgkg-1/m) from Orji and Nekede MVs was 9.2 for Pb; 6.7 for Mn; 6.1 for Zn; 1.5 for Cu; 197 for Fe; 0.3 for Ni; and 0.04 for Cd within 200m distance and 45 cm depth at 10% error. Soil pollution parity between the MVs was not only about difference in the natural geology and geological processes. Waste generation as a function of workshop density, soil texture, acidity and moisture, slope and terrain features, are accountable. Metal dispersion from the MVs far exceeds dispersion from waste dumps. Geophysical measurements show a minimum farming safe distance of 350 m to the MV at slope of 16-18%. Safe depth of shallow water well was estimated as: water table (WT) + 48 m where weathered base is above WT, and WT+66 m at locations were weathered base is below WT. This dissertation found the concept and the general requirements of environmentally friendly mechanic village (EFMV). EFMV will provide the bases for the transfer of emission testing technology, global CO2 emission mitigation, and climate change responses in developing countries. The goal is to make MV a sustainable urban infrastructure, as waste automobile trade to developing countries may assume greater dimensions following transition to green electric cars in developed countries. United Nations, industrialized nations, and other organizations could assist developing countries in automobile wastes management including final end of life vehicles through partnerships.