Ahmad Alahabadi

A comparative study on capability of different tree species in accumulating heavy metals from soil and ambient air

Heavy metals (HMs) in the urban environment can be bio-accumulated by plant tissues. The aim of this study was to compare fourteen different tree species in terms of their capability to accumulate four airborne and soilborne HMs including; zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd). Samplings were performed during spring, summer, and fall seasons. To compare bioaccumulation ability, bio-concentration factor (BCF), comprehensive bio-concentration index (CBCI), and metal accumulation index (MAI) were applied. Species with the highest accumulation for single metal which shown using BCF did not have the highest CBCI and MAI. Based on CBCI and MAI, Pinus eldarica (7.74), Wistaria sinensis (8.82), Morus alba (8.7), and Nigral morus (27.15) had the highest bioaccumulation capacity of HMs, respectively. Therefore, these species can be used for phytoextraction of HMs pollution and green and buffer zone in the urban.

Adsorption property of Br-PADAP-impregnated multiwall carbon nanotubes towards uranium and its performance in the selective separation and determination of uranium in different environmental samples

A newer efficient U(VI) ion adsorbent was synthesized by impregnating Br-PADAP [2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol] onto multiwall carbon nanotubes (MWCNTs). The effects of various operation conditions on uranium adsorption (i.e., pH contact time, temperature, and initial uranium concentration) were systematically evaluated using batch experiments. The results indicated that the uranium adsorption on modified MWNCTs (5.571 × 10-3g/mg × min) reached faster equilibrium than that on pristine MWNCTs (4.832 × 10-3g/mg × min), reflecting the involvement of appropriate functional groups of Br-PADAP on the chelating ion-exchange mechanism of U(VI) adsorption. Modified MWNCTs (83.4mg/g) exhibited significantly higher maximum Langmuir adsorption capacity than pristine MWNCTs (15.1mg/g). Approximately 99% of uranium adsorbed onto modified MWNCTs can be desorbed by 2.5mL of 1M HNO3 solution. Therefore, Br-PADAP-modified MWNCTs can server as a promising adsorbent for efficient uranium adsorption applications in water treatment. Subsequently, the proposed solid-phase extraction (using a mini-column packed with Br-PADAP/MWCNT) was successfully utilized for analysing trace uranium levels by the ICP-AES method in different environmental samples with a pre-concentration factor of 300-fold. The coexistence of other ions demonstrated an insignificant interference on the separative pre-concentration of uranium. the detection limit was recognized as 0.14μg/L, and the relative standard deviation was approximately 3.3% (n = 7).

Application of supramolecular solvent-based dispersive liquid–liquid microextraction for trace monitoring of lead in food samples

In this study, an efficient sample treatment method based on supramolecular solvent-based dispersive liquid–liquid microextraction (SM-DLLME) was applied for trace monitoring of lead by flow injection flame atomic absorption spectrometry. A supramolecular solvent comprising reverse micelles of 1-decanol in tetrahydrofuran (THF) was created by injection of these solvents into the aqueous sample solution. After injection of 1-decanol : THF mixtures into the sample solution, nanomicelles were produced in an ultrasonic bath and the lead–dithizone complex was extracted to the supramolecular phase at optimized pH. The solution was centrifuged and the metal complex formed was extracted into the supramolecular solvent phase. The detection limit for lead ions was 0.4 μg L−1 under the optimized separation conditions. The relative standard deviations for six extraction analysis of 3, 10 and 100 μg L−1 of lead ions were 4.8%, 4.5% and 4.1%. Finally, SM-DLLME was successfully applied for trace monitoring of lead ions in agricultural and food samples.

Environmental determinants of polycyclic aromatic hydrocarbons exposure at home, at kindergartens and during a commute

The aim of this study was to assess the potential health risk of exposure to polycyclic aromatic hydrocarbons (PAHs) at home and kindergarten for pre-school children. The urine samples were taken from 200 pre-school children aged 5-7 years and analyzed for 1-OHP as a biomarker of PAHs. Mixed effect models were applied to investigate the association between effective environmental parameters (mode of transport, distance to major roads, traffic density, greenness, tobacco exposure, home ventilation, and grill foods) and urinary 1-OHP levels. A Monte-Carlo simulation technique was applied to calculate the risk of exposure to PAHs and to check the uncertainty of input variables and the sensitivity of the estimated risk. The median and inter quartile range (IQR) of 1-OHP was 257 (188.5) ng L-1. There was a positive significant association between distance from the kindergartens to the green space with surface area ≥5000 m2 and 1-OHP concentration (β = 0.844, 95% CI: 0.223, 1.46, P-value = 0.009). Also, urinary 1-OHP was found to be inversely associated with the time the window was open at the home (β = -12.56, 95% CI: -23.52, -1.596, P-value = 0.025) and normalized difference vegetation index (NDVI) in a 100 m buffer around the homes. The mean (9.76 E-3) and 95th percentile (3.28 E-2) of the hazard quotient (HQ) indicated that the concentration of urinary 1-OHP is at a safe level for the target population (HQ < 1). According to the sensitivity analysis results, the concentration of 1-OHP is the most influential variable in the estimated risk. Our findings indicated that the proximity of homes and kindergartens to green space areas and their remoteness from the main streets and heavy traffic areas are associated with reduced exposure to PAHs.

Solidified floating organic drop microextraction for pre-concentration and trace monitoring of cadmium ions in environmental food and water samples

In this research, solidified floating organic drop microextraction as an efficient sample preparation method was used for trace monitoring of cadmium ions in environmental samples. In this method, a free microdroplet of 1-undecanol is floated on the surface of aqueous solution and agitated by a stirring bar placed on the bottom of the sample vial. Cadmium ions were complexed with neocuproine to obtain hydrophobic complex and extracted to extraction solvent. The extracted target ions were determined by flow injection–flame atomic absorption spectrometry. The effect of important factors on the extraction of target ions by the proposed sample preparation method was evaluated and optimized. The limit of detection, relative standard deviation (%) and enrichment factor of the method were 0.02, 3.7 and 98.5%, respectively. The validation of the method was examined by the analysis of cadmium ions in the certified reference material (sea food mix), and the obtained data can proof the reliability of the method for trace detection of cadmium ions. The method was successfully applied for determination of cadmium in the real food and water samples, and satisfactory relative recoveries (97–102%) were achieved.

Mortality and morbidity due to exposure to ambient particulate matter

The aim of this study was to investigate spatial variation and health risk of the exposure to PM2.5 (particulate matter with a diameter of 2.5 µm or less) and PM10 (particulate matter with a diameter of 10 µm or less) in Sabzevar, Iran. PM2.5 and PM10 were measured during three campaigns from April to November 2017, in 26 sampling points. Spatial analysis was performed using kriging and autocorrelations (Morans index) model in Arc GIS software. Relationship between exposure to the PM2.5 and PM10 and their health impacts were investigated by AirQ 2.2.3 software. The mean concentrations (and standard deviation) of PM 2.5 and PM10 over the entire study period were 32.54 (37.28) and 42.61 (47.76) μg/m3, respectively, which were higher than the guideline of World Health Organization. According to the spatial analysis, the maximum concentrations of PM2.5 and PM10 were around the main highway (beltway) which placed all over the south of Sabzevar. According to the Morans index, the emission patterns for PM2.5 (Z-score = 2.53; P-value = 0.011) and PM10 (Z-score = 2.82; P-value = 0.004) were clustered. The attributable percentage (AP) of total mortality related to PM2.5 and PM10 were 3.544% (95% confidence interval (CI): 2.623-4.447%) and 2.055% (95% CI: 1.379-2.721%) per increasing each 10 μg/m3 of these pollutants, respectively. According to observed results, it is suggested that the beltway and other pollution sources, such as industries, should be placed at a greater distance from the city, to reduce PM amounts in residential areas.