Ayse Nur Esen

Determining distribution of heavy metal pollution in terms of ecological risk levels in soil of industrially intensive areas around Istanbul

The aims of the present study were to measure the concentrations of As, Cr, Co, Fe, and Zn in soils from two heavily industrialized areas and to assess the degree of heavy metal pollution by using the indices enrichment factor and the geo-accumulation index, as well as assessing the potential ecological risk. The concentrations of the selected elements in the environmental samples were determined by the neutron activation analysis. The pollutant concentrations in the studied areas showed that the soils were characterized by a high pollution from As and Cr due to the industrial facilities in the area. The concentrations in the Tuzla industrial area were 79–1215 mg/kg of Cr, 17–84 mg/kg of As, 22,000–54,000 mg/kg of Fe, 101–258 mg/kg of Zn, and 8–23 mg/kg of Co. The results for the Cerkezkoy industrial area were found to be 46–196 mg/kg of Cr, 6–24 mg/kg of As, 17,000–25,000 mg/kg of Fe, 67–136 mg/kg of Zn, and 7–10 mg/kg of Co. The contamination in the soils from heavy metals was assessed based on enrichment factor, geo-accumulation factors, and ecological risk indices. The results were compared with the data from other industrial areas in Turkey. It was found that the metals As and Cr showed higher concentrations in Tuzla than in other examined industrial areas. The results for Cerkezkoy industrial area indicate that the area is not as contaminated as the other industrial areas in Turkey.

Kinetic modeling of selenium (IV) adsorption for remediation of contaminated aquatic systems based on meso-scale experiments

AbstractThe present study involves selenium (IV) adsorption onto organic pillared bentonite using batch experiments and kinetic modeling, at two different temperatures. selenium (IV) remediation in an aqueous environment, such as contaminated drinking water, groundwater, and industrial wastewater, is the aim of this study. The experimental data were tested with both surface reaction-based and diffusion-based kinetic models to clarify the controlling mechanism of the adsorption process from both microscopic and macroscopic point of view. Among all the investigated models, the most appropriate was the pseudo-second-order surface reaction-based kinetics model. The obtained results proved that the adsorption process at a selenium dioxide concentration of 300 mg L−1 is controlled by the diffusion rate of penetrated selenium (IV) into the reacted layer.

Feasibility study of k 0-INAA at the ITU TRIGA Mark II research reactor, Turkey

This work is focused on testing the implementation of k0-INAA using Kayzero for Windows and k0-IAEA software packages at the ITU TRIGA Mark II research reactor. The neutron spectrum parameters were determined using the bare triple-monitor method with Au and Zr monitors. The k0-INAA performance was tested by analysis of NIST SRMs 2711 Montana Soil and 1547 Peach Leaves. The performance assessment based on the En criterion showed that the concentrations of a number of elements in both NIST SRMs determined by both software packages are in agreement with NIST values.

Instrumental neutron activation analysis of plant tissues and soils for biomonitoring in urban areas in Istanbul

The aim of this study was to determine the elemental concentrations of plant tissues and soils collected in Istanbul to evaluate the possible use of selected tree species, Carpinus betulus L., Quercus petraea (Mattuschka) Liebl., Tilia argentea Desf. ex DC., as biomonitors. The concentrations of 26 elements were determined by k0-INAA using Kayzero for Windows software. Generally, the element concentrations in samples from urban areas were found to be higher than those of control area. Tilia argentea Desf. ex DC. may be an effective biomonitor for As, Br, Ca, Cl, Cr, Fe, Hf, K, Sb, Sc, Sr, and Th.

Measurements on the spectroscopic performance of CdZnTe coplanar grid detectors.

A performance study was performed for CdZnTe coplanar grid (CPG) detectors when used as γ-ray spectrometers. The detectors have the crystal volumes of 1, 1.6875 and 2.25 cm(3), respectively. Time stability of each CdZnTe CPG detector was investigated in a long-term operation (time span of 0.25 to about 100 h). The spectroscopic performances were measured at different bias voltages and at various photon energies ranging from 59.6 keV ((241)Am) to 1332.5 keV ((60)Co) for each detector, and evaluated by using the following parameters: energy resolution in FWHM, peak tailing in peak-to-valley (P/V) ratio and in FWHM/FW.25 M ratio, and photofraction using the acquired γ-ray spectra. No polarization effect was observed in terms of count rate, energy resolution and peak centroid shift. The obtained results indicate that better time stability and excellent spectroscopic performances of the present CdZnTe CPG detectors are shown for a room temperature γ-ray spectroscopy.

Comparison of relative INAA and k0-INAA using proficiency test materials at ITU TRIGA Mark II research reactor

Proficiency testing is an important way of evaluating the analytical method used in the laboratory. In recent years, neutron activation analysis studies performed in ITU TRIGA Mark II reactor comprised five proficiency tests organized by Wageningen evaluating programs for analytical laboratories. In this study, the results obtained by relative INAA and k0-INAA method for 16 elements in soil and plant samples are presented. Since both methods have some advantages compared to each other, the possible approach for the laboratory should be to combine relative INAA and k0-INAA results.

An Overview of Energy Technologies for a Sustainable Future

Population and the economic growth are highly correlated with the energy demand. The world population was multiplied by a factor of 1.59 (reaching above 7 billion) from 1980 to 2013, while the total energy consumption of the world was multiplied by 1.84 (getting beyond 155,000 TWh) in the same time interval. Furthermore, the demand for energy is expected to increase even more with an average annual rate of 1.2 % in the near future. However, for the last 30 years, about 85–90 % of the energy demand is supplied by petroleum, natural gas, and coal, even though they are harmful for the environment and estimated to be depleted soon. Hence, building energy policies to satisfy the needs of increasing population and growing economy in a sustainable, reliable, and secure fashion has become quite important. This may involve optimizing the energy supplies, minimizing the environmental costs, promoting the utilization of clean and renewable energy resources and diversifying the type of energy sources. Thus, not only the conventional energy generation technologies must be developed more, but also environmentally friendly alternative energy sources (such as wind, solar, geothermal, hydro, and bio) must become more widespread to sustain the energy needs for the future. However, this requires a significant amount of research on energy technologies and an effective management of the energy sources.