Cerenkov counting technique

A review is presented on the progress made in the Cerenkov counting technique. History, theory, and applications have shown that this technique is simple, easy, and can be used for the determination of low levels of radionuclides with a low background liquid scintilation counter. It has been applied to the measurement of radioactive biological tracers, fission products (⁹⁰sr,⁸⁹Sr) and natural radionuclides (²²²Rn,²²⁶Ra,²²⁴Ra,²¹⁰Pb,²²⁴Th,²²⁸Th,²³⁸U) in various types of samples. Advantages and disadvantages of this technique are summarized.     

Determination of natural radioactivity in Euphrates river

Levels of naturally occuring radionuclides (radium isotopes, U isotopes, ²¹⁰Po and ²¹⁰Pb) in water, sediments and biota samples collected from Euphrates river during the 1999–2000 period have been determined. Results have shown that the water contained relatively high levels of ²²⁶Ra; the largest value of 1150 mBq·l^–1 was observed. These relatively high levels of ²²⁶Ra, which is one of the main radioactive contaminants in the oil industry, may be due to past discharges of production water from the oil fields situated near the river banks. ²²⁶Ra/²³⁸U activity ratio was found to be more than unity in all water samples varying between 13 and 242. In addition, the results of sediment analyses have also shown lower values for ²²⁸Ra/²²⁶Ra activity ratio than unity in those samples collected nearby the oil fields. Moreover, concentrations of other naturally occurring radionuclides such as uranium isotopes, ²¹⁰Po and ²¹⁰Pb for most samples (water, sediments and biota) were found to be within the natural levels and in agreement with those values reported for other local and international studies. Only mussel species were found to contain high levels of ²¹⁰Po, about 1335 Bq·kg^–1 dry mass was observed in Anodonta sp species. However, the results of this study can be considered a baseline for monitoring of future changes. A regional research project (including Turkey, Syria and Iraq) to study this river (from the Anatolia Mountains to the Arabian Gulf) is necessary to determine the impact of all potential sources of contaminants.This revised version was published online in November 2005 with corrections to the Cover Date.     

Evaluation of trace-element pollution in Barada River environment by instrumental neutron activation analysis

The impact of tanning and electroplating industry on the eastern part of Barada River environment has been evaluated. Sediment, soil and plant samples were collected from nine sites at the river near the eastern industrial complex during 1999. Results of instrumental neutron activation analysis have shown high levels of Cr in sediment collected near the tanning factories; the highest value obtained being 2692 ppm. In addition, relatively high levels of Cr were also found in the agriculture soil collected near the riverbank in the industrial complex; Cr concentrations varied between 77 ppm and 327 ppm. However, Cr concentrations in plant leaves grown at riverbank were found low and this due to strong bounding of Cr to soil. Other trace metals such as copper and nickel were also high in sediment samples. The highest concentration of copper was about 4000 ppm, which is much higher than the natural levels; electroplating shops are the main source of this element in the area. Furthermore, concentrations of the studied trace metals have decreased as the sampling site distance became far from the industrial complex. In general, other trace elements were found to be at low concentrations, but the obtained data can be used as a baseline for future monitoring.     

Biosorption of Cadmium,Lead, and Uranium by Powder of Poplar Leaves and Branches

The removal of metal ions from aqueous solutions by biosorption plays an important role in water pollution control. In this study, dried leaves and branches of poplar trees were studied for removing some toxic elements (cadmium, lead, and uranium) from aqueous solutions. The equilibrium experiments were systematically carried out in a batch process, covering various process parameters that include agitation time, adsorbent size and dosage, initial cadmium, lead and uranium concentration, and pH of the aqueous solution. Adsorption behavior was found to follow Freundlich and Langmuir isotherms. The results have shown that both dried leaves and branches can be effectively used for removing uranium, while only branches were found to remove lead and cadmium completely from the aqueous solution. The maximum biosorption capacity of leaves for uranium was found to be 2.3 mg g⁻¹ and 1.7 mg g⁻¹ and 2.1 mg g⁻¹ for lead and cadmium on branches, respectively. In addition, the studied biomass materials were used in removing lead and cadmium from contaminated water and the method was found to be effective.     

Treatment of produced water using walnut shell for 226Ra removal

Journal of Radioanalytical and Nuclear Chemistry - Sorption and desorption of 226Ra from produced water with oil production on walnut shell media were investigated using batch-type and column-type...     

Transfer of 226Ra, 85Sr and 137Cs from milk to milk products</p> </p>

Summary Transfer of ²²⁶Ra, ⁸⁵Sr and ¹³⁷Cs from cow and sheep milk to various Syrian dairy products has been evaluated. Dairy products include Kashkivan cheese, braided cheese, Haloom cheese, Sircassian cheese, liquid cheese, native cheese, cottage, thick yogurt, butter and milk cream. The results showed that the percentage of ²²⁶Ra, ⁸⁵Sr and ¹³⁷Cs transferred from cow milk to milk cream (P_t=food processing retention factor′processing efficiency′100%) has reached 32%, 16% and 7%, respectively. Butter and liquid cheese were found to have the lowest percentage of transferred 226Ra, ⁸⁵Sr and ¹³⁷Cs. Most of the obtained P_t values of the studied radionuclides in thick yogurt were relatively low in spite of the high processing efficiencies of thick yogurt. Moreover, the transfer, P_t, of the studied radionuclides from cow milk to the prepared cheese was higher than those values determined for sheep milk. This is due to differences in chemical compositions of each type of milk. On the other hand, the treatment of Native cheese, most commonly consumed cheese in Syria, with different concentrations of NaCl solutions showed that ¹³⁷Cs was completely removed from cheese soaking in 5% NaCl solution (soaking time of 48 hours), while 40% of ²²⁶Ra and 80% of ⁸⁵Sr were also decontaminated using 0-2.5% NaCl solutions and soaking time of 48 hours. Based on the obtained results, industrialization processes of the dairy products that resulted the removal of radionuclides have been identified.</p> </p>     

Use of the Eurachem guide on method validation for determination of uranium in environmental samples

Three analytical methods for determination of uranium in environmental samples by a fluorescence technique have been validated and compared in accordance with the Eurachem Guide on method validation. The first method depends on uranium separation from iron using the mercury anode technique; in the other two methods uranium is separated from iron on an anion exchange column by use of either a solution of hydrochloric acid containing ascorbic acid and hydrazine hydrate or a dilute sulfuric acid solution. Detection limits, repeatability, reproducibility, and recovery coefficient were the main validation characteristics. The results showed that better statistical values can be achieved by using the third method. Control charts for in-house control samples and international intercomparison samples have also shown that the third method is more statistically stable with time. In addition, uncertainties of measurement were estimated and compared for the three methods. It was found that the Eurachem Guide and comparison of quality statistical validation data can be good tools for selection of the appropriate method for an application.     

Comparison of transfers for natural radionuclides (238U, 234Th, 226Ra, 210Pb & 210Po) from five different soils to four different barley genotypes

Transfer Factors (Fv) of ²³⁸U, ²²⁶Ra, ²³⁴Th, ²¹⁰Po and ²¹⁰Pb from five different agricultural soils in semi-arid region (Syria) to four different barley genotypes were studied in an agricultural potted experiment. The geometric mean of the Fv values were (0.08) for ²¹⁰Pb, and (0.02) for ²¹⁰Po, while it ranged from 0.18 to 0.42 ,from 0.08 to 0.15 and from 0.22 to 0.4 for ²³⁸U, ²³⁴Th and ²²⁶Ra, respectevily. The Fv values of ²³⁸U and ²²⁶Ra were within the recommended global medians, while the Fv values of ²³⁴Th, ²¹⁰Pb and ²¹⁰Po were higher. There is no clear relationship between the soil properties and Fv of all studied radionuclides to barley genotypes. Moreover, the expression of glutathione (GSH) gene, which is belived to be involoved in heavy metal removal was generally low in all studied varieties grown in all soil types.

     

Derivatization of 2-chlorophenol with 4-amino-anti-pyrine: a novel method for improving the selectivity of molecularly imprinted solid phase extraction of 2-chlorophenol from water

Molecularly imprinted polymer (MIP) may not selectively recognize small template of limited number of functional groups, such as 2-chlorophenol (2-CP). In this work, a novel method was proposed to improve the recognition ability of the molecularly imprinted solid phase extraction (MISPE) of 2-CP from environmental waters. This was achieved by derivatization of 2-CP with 4-amino-anti-pyrine (4-AAP) to enlarge its molecular size and add more binding sites. For that purpose, two MISPE methods of 2-CP were developed. In method 1, a polymer imprinted with 2-CP was used as the extracting sorbent but it suffered from low selectivity and high detection limit of 2-CP (7.10 ng L⁻¹). In method 2, a polymer imprinted with 4-AAP derivatized 2-CP (2-CP-4-AAP) was used as the extracting sorbent. Prior to loading the water sample it was subjected to a simple derivatization procedure with 4-AAP. Method 2 showed high recognition ability/selectivity towards 2-CP-4-AAP with lower detection limit of 0.05 ng L⁻¹ for 2-CP-4-AAP. Method 2 was able to detect the presence of 2-CP-4-AAP in unspiked real water samples and almost full spike recovery was achieved.     

Synthesis and molecular structures of (2-dialkylaminophenyl)alcohols and of 2-phenylaminoalkyl-dimethylaminobenzene derivatives

N,N-Dimethyl-o-toluidine, N,N-dimethylaniline, and N,N-diethylaniline were treated with n-butyllithium-tmeda in diethyl ether-hexane solution to give o-lithioarylamines, which react with various electrophiles (benzophenone, dicyclohexyl ketone, benzaldehyde, and Ph(H)CNPh) to form the corresponding (2-dialkylaminophenyl)alcohols 1-HOCPh₂-2-NMe₂C₆H₄ (1), 1-HOCCy₂-2-NMe₂C₆H₄ (2), 1-HOCPh₂CH₂-2-NMe₂C₆H₄ (4), 1-HOC(H)PhCH₂-2-NMe₂C₆H₄ (6), and 1-HOCPh₂-2-NEt₂C₆H₄ (7), and the 2-phenylaminoalkyl-dimethylaminobenzene derivatives 1-NMe₂-2-NH(Ph)C(H)PhC₆H₄ (3) and 1-NMe₂-2-NH(Ph)C(H)PhCH₂C₆H₄ (5). Compounds 1-7 were characterized spectroscopically (NMR, IR, MS) and by crystal structure determination.