Agama lizard: A potential biomarker of environmental heavy metal pollution assessment

In this study, the suitability of Agama lizard as a biomarker in assessing environmental pollution levels of arsenium (As), barium (Ba), cadmium (Cd), copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) was investigated. Samples of top soil and agama lizards were taken from five sites within a university community in Nigeria for the study. Soil samples, livers and kidneys from the lizards were subjected to wet acid digestion and levels of heavy metals in the digested samples were determined using an atomic absorption spectrophotometer (AAS). Results of the study showed that the levels of the metals ranged from Cd, 20.4 ± 2.6 ìg/g to Zn, 978.6 ± 2.2 ìg/g in soil; Cd, not detected to Zn, 42.2 ± 0.3 ìg/g in liver; As and Ba, not detected to 47.6 ± 1.0 ìg/g Zn in kidney. The inter matrices correlation coefficient values obtained for the heavy metals showed that the kidney of lizards would be more relevant in assessing soil levels of such heavy metals as As, Ba, Cd, Mn and Pb among others.Key words: Agama lizard, environmental pollution, soil, heavy metals, liver, kidney

The electrical conductance and viscosity of Nigerian traditional soaps in alcoholic media

The electrical conductances and viscosities of Nigerian traditional soaps in alcohols have been measured. Potassium, sodium and potassium/sodium (50:1) soaps have been prepared from palm kernel oils using laboratory prepared reagent alkalis and their conductances have also been measured. While the conductances vary with the degree of purity of the soaps and the polarity of the solvents, the activation energy for conductance only varies with the change of solvents. The conductances of the laboratory prepared potassium soaps are higher than those of the sodium soaps, suggesting the metal ions to be the main charge carriers in solution. Plots of logarithm of conductivity against inverse temperature are linear for all the soaps in methanol and ethanol while such plots are non-linear in propan-1-ol in which the soaps are least soluble with lowest conductance values. However, the plot is linear for the laboratory prepared potassium soap in propan-l-ol. The conductivities of the commercial (traditionally prepared) soaps are found to be higher than those of the laboratory prepared ones, indicating the formation of soaps of many fatty acid constituents of palm kernel oil in the traditional process of soap preparation. The variations of the viscosities of the solutions with concentration, temperature and carbon chain length of the solvents are also discussed. The plots of log(10) eta versus 1/T for all the soap solutions are linear suggesting that the solutions are non-associated liquid systems in agreement with the conductance data. The variations of the activation energies obtained from these plots with concentration and molecular weights of the solvents are discussed. The viscosity data are also interpreted on the basis of Jones-Dole equation. The trend of the B-coefficient of this equation suggests that the soaps become less ideal with increase in the molecular weights of the alcohols. The erratic nature of the A-coefficient values is again related to the results of conductance measurement which indicate that the traditional method of soap preparation produces mixed soaps and that the soaps contain many trace metal ions. (C) 2001 Elsevier Science B.V. All rights reserved