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Management of waste electrical and electronic equipment (WEEE) has recently attracted worldwide attention because of high metal concentrations in them. Evolution of toxic and precious metals utilized in WEEE can not only reflect the adventure of eco-design, but can also guide the final recycling option. Pb, As, Cu, Au, Sn and Ag were determined in 10 composite samples of printed circuit boards of cathode ray tube televisions (TV-PCBs) that were produced between 1980 and 2005. The obtained results indicated that average metal concentrations in all TV-PCBs were - Cu: 10.6 ± 4.1%, Sn: 4.21 ± 0.90%, Pb: 3.15 ± 0.54%, Ag: 0.0215 ± 0.0068%, Au: 0.0068 ± 0.0049% and As: 0.0007 ± 0.0004%. No remarkable difference was found in compositions of Pb and Sn over the years, suggesting that there were no major modifications of Sn/Pb solder used in joining the circuitry system. The average composition of Cu fluctuated between 5.10% in 1980 and 12.8% in the mid-1990s and decreased afterwards. The decreases in Ag and Cu compositions could possibly be associated with thinner layers of these metals in newer model products.

In this study, soil contamination by toxic metals released from cathode ray tubes (CRTs) openly discarded within the vicinities of artisans' workshops in Nigeria was assessed in order to ascertain the metal leaching potential of CRTs, mobility and bioavailability of the leached metals in soil. Furthermore, the ecological geochemistry of the impacted soils was carried out. Seventy soil samples were randomly collected from thirty five locations at depths 0 - 15 cm (topsoil) and 15 - 30 cm (sub-soil), respectively from two selected states each within five geographical regions of Nigeria. Environmentally available lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni) and copper (Cu) were extracted from dried and sieved soil samples using aqua regia solution and were analyzed using flame atomic absorption spectrometry (AAS). Additionally, the metals were also sequentially extracted into five fractions and their concentrations determined using AAS. Concentration of Pb ranged from 0.4 - 6510 mg/kg with all top-soils exceeding the Nigerian NESREA regulatory limit of 164 mg/kg while Cd, Cr, Ni and Cu levels were within their respective regulatory limits. Geoaccumulation index values indicated that approximately 83% of all top-soils represented strong to extreme contamination by Pb while sequential extraction showed that majority of the extracted Pb was in the Fe-Mn oxide, residual and exchangeable forms. The results generally suggest that CRT disposal areas are highly polluted with Pb with significant amounts in bioavailable phases. Thus, waste CRTs are required to be managed in an environmentally sound manner to forestall any probable harm to ecological functioning of such areas. [ABSTRACT FROM AUTHOR]