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This study reports a spatiotemporal characterization of toluene, benzene, ethylbenzene, and xylenes concentrations (BTEX) in an urban hot spot in Iran, specifically at an bus terminal region in Shiraz. Sampling was carried out according to NIOSH Compendium Method 1501. The inverse distance weighting (IDW) method was applied for spatial mapping. The Monte Carlo simulation technique was applied to evaluate carcinogenic and non-carcinogenic risk owing to BTEX exposure. The highest average BTEX concentrations were observed for benzene in the morning (at 7:00–9:00A.M. local time) (26.15±17.65μg/m3) and evening (at 6:00–8:00P.M. local time) (34.44±15.63μg/m3). The benzene to toluene ratios in the morning and evening were 2.02 and 3.07, respectively. The main sources of BTEX were gas stations and a municipal solid waste transfer station. The inhalation lifetime cancer risk (LTCR) for benzene in the morning and evening were 1.96×10−4 and 2.49×10−4, respectively, which exceeds the recommended value by US EPA and WHO. The hazard quotient (HQ) of all these pollutants was less than 1. The results of this work have implications for public health near ‘hot spots’ such as IKBT where large populations are exposed to carcinogenic emissions.

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BackgroundThe adsorption process by metal oxide nanoparticles has been investigated an effective agent for removing organic and inorganic contaminants from water and wastewater. In this study, iron oxide nanoparticles were synthesized in the presence of tangerine peel extract as adsorbent for cadmium ions removal from contaminated solution. Iron oxide nanoparticles prepared by co-precipitation method and tangerine peel extract was used to prevent accumulation and reduce the diameter of the particles. Effect of various parameters such as contact time, pH, metal concentration and adsorbent dosage was determined on the removal efficiency.ResultsThe different concentrations of tangerine peel had an impact on the size of nanoparticles. As, increasing the concentration of tangerine peel extract from 2 to 6 % the average size of synthesized iron oxide nanoparticles decreased 200 nm to 50 nm. The maximum removal of cadmium ions (90 %) occurred at pH of 4 and adsorbent dose of 0.4 g/100 ml. Adsorption of cadmium ions by synthesized iron oxide nanoparticles followed Freundlich adsorption model and pseudo-second-order equation.ConclusionThe cadmium ions are usually soluble in acidic pH and the maximum removal of cadmium by green synthesis iron oxide nanoparticles was obtained in the pH of 4, so these nanoparticles can be a good adsorbent for the removal of cadmium from wastewater.