Health implications to the population due to the consumption of contaminated vegetables has been a great concern all over the world. In this study, the levels of heavy metals (Cr, Cd, Zn, Fe, Pb, As, Mn, Cu, Hg, Ni and Co) in soil and commonly consumed vegetables from Mojo area in central Ethiopia have been determined using Inductively Coupled Plasma Optical Emission Spectrophotometer (ICP-OES) and possible health risks due to the consumptions of the vegetables have also been estimated. The levels of As, Pb, Cd, Zn, Cu, Hg and Co were exceeded the reference level in agricultural soil. Likewise, As, Pb, Cd, Cr and Hg levels exceeded the recommended values in vegetable samples with concentrations rang

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Contaminated soil and vegetables have continued to instigate threat to human health globally and specially in developing countries. This study was aimed to determine concentrations of certain heavy metals in soil and vegetables (cabbage and tomato) from Koka area of central Ethiopia using Inductively Coupled Plasma Optical Emission Spectrophotometer (ICP-OES). The amounts of As, Pb, Cd, Zn, Cu, Hg and Co detected in soil samples were found to surpass the reference values for agricultural soil. Similarly, the concentrations of As, Pb, Cd, Cr and Hg obtained in both tomato and cabbage samples have exceeded the recommended values with the mean levels generally ranging from 0.93–6.76, 1.80–7.26, 0.33–1.03, 0.86–5.16 and 3.23–4.36 mg/kg dry weight, respectively. The result obtained have signified that leafy vegetable has hoarded heavy metals more than non-leafy vegetable. The total hazard quote for As and Hg from tomato ingestion and for As, Hg and Co from cabbage ingestion were greater than unity, signifying potential health hazard to the public. The health index (HI) owing to tomato and cabbage ingesting were 5.44 and 14.21, respectively, signifying likely adversative health implication to the population from the ingestion of the vegetables. The Total Cancer Risk (TCR) analysis have uncovered the possible cancer hazard persuaded by Cd, Hg, As and Ni from the ingestion of both vegetables. From the outcomes this study, it can be concluded that the soil and vegetables from Koka areas are possibly contaminated with toxic metals and hence demand strict monitoring to safeguard the public around the study area and beyond.

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The hydrolysis reaction rate of p-nitrophenyl benzoate (p-NPB) has been examined in aqueous buffer media of pH 9.18, containing surfactants, cetyltrimethylammonium bromide (CTAB) and chloride (CTAC), or sodium dodecyl sulfate (SDS) at 35°C. Although the rate constant [log (k/s −1 )] of p-NPB hydrolysis has once decreased slightly below the critical micelle concentration (CMC) value for CTAB and CTAC, it has begun to increase drastically with micellar formation. With increasing concentrations larger than the CMC value, the log (k/s −1 ) value has reached the optimal value, i.e., a 140-and 200-fold rate acceleration for CTAB and CTAC, respectively, compared to that without a surfactant. Whereas the anionic surfactant, SDS, has caused only a gradual rate deceleration in the whole concentration range (up to 0.03 mol dm −3 ). Increases in pH of the buffer have resulted in increases of the hydrolysis rate. In the CTAB micellar solution, the remarkably enhanced rate has been retarded significantly by the addition of only 0.10 mol dm −3 bromide salts. The effects of rate retardation caused by the added salts follows in the order of NaBr > Me 4 NBr > Et 4 NBr > Pr 4 NBr > n-Bu 4 NBr. In the absence of surfactant, however, the addition of the bromide salts has accelerated the hydrolysis rate, except for the metallic salt of NaBr, with the order of Me 4 NBr < Et 4 NBr < Pr 4 NBr < n-Bu 4 NBr. In the CTAC micellar solution, similar rate retardation effects have been observed in the presence of chloride salts (NaCl, Et 4 NCl, and n-Bu 4 NCl). The effects of added salts have