Научная статья на тему 'Seeking for radioactive graphite in the forest litter'

Seeking for radioactive graphite in the forest litter Текст научной статьи по специальности «Химические технологии»

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Ключевые слова
14C / LSC / carbide / benzene / vacuum pyrolysis / forest litter / radioactive graphite / 14C / РСЛ / карбід / бензол / вакуумний піроліз / лісова підстилка / радіоактивний графіт / 14C / ЖСС / карбид / бензол / вакуумный пиролиз / лесная подстилка / радиоактивный графит

Аннотация научной статьи по химическим технологиям, автор научной работы — Mykhailo Buzynnyi, Vadym Skrypkin

Objective: Our goal was to introduce the differential method for the investigation of 14C in the samples of the environment that were inhomogeneous by the content of 14C and by the inhomogeneity of thermo-destruction of their components. We estimated sensitivity and reproduction of the method. Materials and methods: For the investigation of 14C we used traditional method on the basis of liquid scintillation count and applied vacuum pyrolysis for the component preparation of the forest litter in the search of radioactive graphite. Results and conclusions: We compared the results of the application of vacuum pyrolysis technology (Skripkin & Kovaliukh, 1997) for the production of benzene samples where the fractions of one and the same sample were processed together or separately. 14C is indicated systematically more by 51.5% in the prepared separate second fraction of two ones of the samples in comparison with the joint sample of two fractions (R2 = 0.9554).Systematically, there was 14C more by 51.5% in the prepared separate second of two fractions of the samples in comparison with the joint sample of two fractions (R2 = 0.9554).

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Текст научной работы на тему «Seeking for radioactive graphite in the forest litter»



sedentary time with adiposity in children. Int. J. Obes. (Lond). 2016. Vol. 40 (1). P. 28-33.

6. Moon J.Y, Wang T., Sofer T., North K.E. Objectively Measured Physical Activity, Sedentary Behavior, and Genetic Predisposition to Obesity in U.S. Hispanics/Latinos: Results From the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Diabetes. 2017. Vol. 66 (12). P. 3001-3012.

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SEEKING FOR RADIOACTIVE GRAPHITE IN THE FOREST LITTER

adiocarbon analyses have wide application. Sample materials used for study of 14C concentration may have sub-materials with different radiocarbon concentration or sub-materials may have different particular thermodestruction peculiarities, which may cause radiocarbon variation in corresponding counting media (benzene). Thus, talking about 14C concentration in sample, one take into account, what he want to know: anything, just average and/or subcomponents mentioned above. To have measured reproducible any of component, sample mass should be taken in reproducible amount.

Radioactive graphite of Chornobyl NPP's releases

1BUZYNNYI MYKHAILO, 2SKRYPKIN VADYM

1SI «O.M. Marzeyev Institute of Public Health, NAMS of Ukraine», Kyiv 2SI «Institute of Environmental Geochemistry, NAS of Ukraine», Kyiv

UDK 621.039.86

Keywords: 14C, LSC, carbide, benzene, vacuum pyrolysis, forest litter, radioactive graphite.

ДОСЛ1ДЖЕННЯ РАД1ОАКТИВНОГО ГРАФ1ТУ У Л1СОВ1Й П1ДСТИЛЦ1 1Бузинний М.Г., 2Скрипюн В.В.

1ДУ «1нститут громадського здоров'я im. О.М. Марзеева НАМН Укра!ни», м. Кив

2 ДУ «1нститут reoxiMiï навколишнього середовища НАН Укра!ни», м. Кив

Метою роботи е запровадження диферен^йного методу досл '1дження 14C у пробах довклля неоднордних за вмстом та за особливостями !хньо! термодеструкцп, о^нка чутливостi та вiдтворюваностi методу.

Матер'али iметоди. Використовували традицйний метод досл'1джень 14C на основi рдинно-сцинтиля^йного обчислення, застосовували вакуумний пiролiз, зокрема для покомпонентно!' пдготовки проб л'юовоï пдстилки у пошуках радiоактивного графту.

Результати i висновки. Ми порiвняли результати застосуван-ня технологи вакуумного пiролiзу (Skripkin & Kovaliukh, 1997) для отримання зразкiв бензолу, де фракци одного i того ж зразка були оброблен '! разом або окремо. Пдготовлена окре-мо друга з двох фрак^й зразюв систематично дае на 51.5% бльше 14C пор!вняно зi спльним зразком з двох фрак^й (R2=0.9554).

Ключов'1 слова: 14C, РСЛ, карб'щ, бензол, вакуумний пiролiз, лiсова пдстилка, радюактивний графт.

© Бузинний М.Г., Скрипкн В.О. СТАТТЯ, 2018.

71 Environment & Health №3 2018

into environment high 14C activity in small volume. Behavior of those radioactive graphite was studied on forest ecosystem [3, 4].

Spatial distribution of Chornobyl radioactive graphite was estimated on samples of forest litter and upper soil layer collected during summer of 1997 [2].

Table

Radiocarbon (pMC)a in the samples of various layers

of forest litter for observation sites. Coordinates of sampling sites for studying14C in the Chornobyl NPP vicinity (E-longitude, N-latitude) [1, 2]

Site Longitude (E) Latitude (N) Layer 14C, pMC

«Two fractions» «Pyrolysis» «Charcoal»

96/04 30°5'15'' 51°22'40" Total 385.3 193.9 451.8

96/13 30°4'0'' 51°23'25" A 132.2c 121.3 130.2

96/13 30°4'0'' 51°23'25" B 127.1c 124.8 126.1

96/13 30°4'0'' 51°23'25" C 152.4c 134.9 156.2

96/17 30°7'25" 51°21'50" A 125.0c 126.6 126.1

96/17 30°7'25" 51°21'50" B 135.8c 131.7 132.4

96/17 30°7'25" 51°21'50" C 155.8c 137.0 154.0

96/33 30°3'38'' 51°23'25" A 122.5 119.6 120.3

96/33 30°3'38'' 51°23'25" B 126.9 121.5 120.7

96/33 30°3'38 '' 51°23'25 '' C 132.7 123.9 130.6

96/34 30°4'30'' 51°23'26 '' Total 135.5 122.8 132.1

96/36 30°4'30'' 51°24'0'' Total 188.1

96/36 30°4'30 '' 51°24'0'' A 125.0c 124.8 127.0

96/36 30°4'30 '' 51°24'0'' B 134.2c 124.4 130.5

96/36 30°4'30'' 51°24'0'' C 207.1c 142.3 226.0

97/06 30°6'20'' 51°25'10'' A 123.0 119.2 122.9

97/06 30°6'20'' 51°25'10'' B 123.8 127.1 129.5

97/06 30°6'20'' 51°25'10'' C 149.1 126.1 132.1

97/08 30°0'55'' 51°29'5" A 116.1 115.9 116.7

97/08 30°0'55'' 51°29'5'' B 121.3 115.5 120.7

97/08 30°0'55'' 51°29'5'' C 126.8 118.1 129.6

97/24 30T52" 51°23'3'' A 126.8 121.8 121.2

97/24 30T52" 51°23'3'' B 147.8 126.0 136.2

97/24 30T52" 51°23'3" C 561.2 742.1

TLb — — A 130.0 129.0 133.3

TLb — — B 272.0 161.0 332.1

TLb — — C 378.0 191.6 655.5

97/25 Total 116.4 117.0

a pMC is the percent of «modern» 14C, a relative unit that expresses the 14C activity in the carbon of the Oakwood of 1890 growth (100 pMC = 226 Bq/kgC). bThe sampling site is outside our network. c Old data, which are presented first.

In this case, the forest litter samples were collected from the ground surface and were sampled from an area of 2500 cm2 (50 x 50 cm). The samples were stratified by 3 layers according to their morphological state: A - upper layer: fresh sagged needles;

B - middle layer: old needles without structural changes; C - lower layer, adjacent with upper soil layer: destroyed needles and other humuslike substances.

The relative average distribution of the mass of forest litter samples for 38 sites was found to be A = (13 ± 5)%; B = (29 ± 10)%; and C = (58 ± 11)% [2].

Samples of total litter were collected in 3 sites where we could not stratify the forest litter by layers.Results of above cited paper were obtained using of two stages vacuum pyrolysis [5] for processing of corresponding organic material of layer. We found that application of those approach is quite sensitive for discovering of graphite deposition in environment even 10 years after accidental release [2].

Aim of the study is to introduce a differential method for investigating 14 C in environmental samples that are heterogeneous in content and in terms of their thermal degradation, estimation of sensitivity and reproducibility of the method.

Methods. When studying radioactive graphite dispersion in forest environment [2] we had used vacuum pyrolysis method [5], i.e. sample carbide was prepared in two stages: one - while pyrolysis occur all gaseous carbonaceous materials were absorbed into lithium alloy and second all resulting charred material of forest litter was melted directly with lithium in the same reaction vessel. Thus we had missed 14C details of sample material

№ 3 2018 Environment & Health 72

fractions. Again, coming back to the same sample's material, now (2018) we used vacuum pyrolysis method [5] considering two above mentioned components of each sample prepared separately and comparing them with data we had got earlier [2].

Two sub-samples were pro-ducedone by one by separate carbide formation. Now we use some residual material of about 5 g for each sample, which we still have at the moment a long time after initial work. Benzene samples were measured using of Perkin Elmer LS spectrometer Quantulus 1220TM and corresponding optimized small volume Teflon vials [6].

Results and discussion. Thus, all available data we put together in table, where, we include already published data of table [2], called as «two stages», and we enclose (in the same column) some our earlier similar data, which was not shown at [2], i.e. sampling sites: 96/13, 96/17 and 96/36. Besides of that, in table, we had enclosed separate data of two fractions, called as («pyrolysis» and

nPOB^EMM HOPHOBM^fl =

(«charcoal»), which were obtained now using our two separate fractions approach.

Comparing all 14 C data enclosed in table, which we had got on the same sample set using of different approaches of vacuum pyroly-sis: total two stage and separate stages («two stages» vs «pyrolysis» and «charcoal») we find that in the same sample value of «pyrolysis» is, in most cases, lower than «char-coal». So as it was concluded in [2], most of activity associated with graphite has being preserved while sample processing by charring or vacuum pyrolysis procedure during of sample preparation. Compared data for total two stages method «two stages»

Figure

Comparison of 14C concentration in charred material «charred» samples and charcoal samples obtained by vacuum pyrolysis «charcoal»

1000

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o

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co o o

O

100

Vx' £ X

x

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10

y=1,5147x - 17,433 R2=0,9554

I I I

10

100 1000 «Two stages» A14C, pMC

and new - «charcoal» correlate well (R2 = 0.9554), when new data «charcoal» are systematically 51.5% higher, see figure. This is simple to explain as «two stages» data have total 14C of those two stages when «charcoal» is higher, as it is not diluted by «pyrolysis» fraction, which is lower in most cases as it was mentioned above.

Conclusions

Vacuum pyrolysis technology allows simple production of benzene sample for most kind of sample materials. It allows utilize gaseous carbon-containing material for production of carbide, which releasewhile pyrolysis.

Sample materials, which have different 14C concentrations and/or different thermodestruction properties can be processed together or separate aiming joint or separate analyze of sub-materials fractions.

Use about 5 g of dry forest litter material allow us preparing two fraction samples in most cases.

Comparison of 14C concentration in forest litter samples, which have being contaminated due to Chornobyl accident by radioactive graphite shows significant difference depending on kind of vacuum pyrolysis technology used: two stage total or two separate fractions. Those 14C data sets, obtained for total «two stages» sample and for sample based on charcoal resulting after pyrolysis, give strong correlation, when «charcoal» are systematically 51.5% higher.

73 Environment & Health №3 2018

INVESTIGATION OF RADIOACTIVE GRAPHITE

IN THE FOREST LITTER

1Mykhailo Buzynnyi, 2Vadym Skrypkin

1SI «O.M. Marzeyev Institute for Public Health, NAMSU», Kviv

2SI «Institute of Environmental Geochemistry, NASU», Kviv

Objective: Our goal was to introduce the differential method for the investigation of 14C in the samples of the environment that were inhomogeneous by the content of 14C and by the inhomogeneity of thermo-destruction of their components. We estimated sensitivity and reproduction of the method. Materials and methods: For the investigation of 14C we used traditional method on the basis of liquid scintillation count and applied vacuum pyrolysis for the component preparation of the forest litter in the search of radioactive graphite. Results and conclusions: We compared the results of the application of vacuum pyrolysis technology (Skripkin & Kovaliukh, 1997) for the production of benzene samples where the fractions of one and the same sample were processed together or separately. 14C is indicated systematically more by 51.5% in the prepared separate second fraction of two ones of the samples in comparison with the joint sample of two fractions (R2 = 0.9554).Systematically, there was 14C more by 51.5% in the prepared separate second of two fractions of the samples in comparison with the joint sample of two fractions (R2 = 0.9554).

Keywords: 14C, LSC, carbide, benzene, vacuum pyrolysis, forest litter, radioactive graphite.

ИССЛЕДОВАНИЕ РАДИОАКТИВНОГО ГРАФИТА

В ЛЕСНОЙ ПОДСТИЛКЕ

1Бузынный Михаил, 2Скрипкин В.В.

1ГУ «Институт общественного здоровь им.О.М. Маозеева НАМН Украины» 2ГУ «Институт геохимии окружающей среды НАН Украины», г. Киев

Целью работы являются введение дифференциального метода исследования 14C в пробах окружающей среды неоднородных по содержанию 14C и по неоднородности термодеструкции их компонент, оценка чувствительности и воспроизводимости метода.

Материалы и методы. Использовали традиционный метод исследований 14C на основе жидкостносцинтилляционного счета. Применяли вакуумный пиролиз, в частности для покомпонентной подготовки проб лесной подстилки в поисках радиоактивного графита. Результаты и выводы. Мы сравнили результаты применения технологии вакуумного пиролиза (Skripkin&Kovaliukh, 1997) для получения образцов бензола, где фракции одного и того же образца были обработаны вместе или по отдельности. Подготовленная, отдельная вторая из двух фракций образцов систематически дает на 51.5% больше 14C по сравнению с общим образцом из двух фракций (R2 = 0.9554).

Ключевые слова: 14C, ЖСС, карбид, бензол, вакуумный пиролиз, лесная подстилка, радиоактивный графит.

Л1ТЕРАТУРА

1. Buzinnyi M., Likhtarev I., Los' I., Talerko N., Tsigan-kov N. 14C Analysis of Annual Tree Rings from the Vicinity of the Chornobyl NPP. Radiocarbon. 1997. № 40 (1). P. 373-379. doi:10.1017/ S0033822200018257

2. Buzinnyi M. Radioactive Graphite Dispersion in the Environment in the Vicinity of the Chornobyl Nuclear Power Plant. Radiocarbon. 2006.

№ 48 (3). P. 451-458. doi:10. 1017/S003382220003887X

3. Ковалюх Н.Н., Скрип-кин В.В., Соботович Э.В. и др. Радиоуглерод аварийного выброса Чернобыльской АЭС в годовых кольцах деревьев в окрестностях ЧАЭС. Zeszyty Naukowe Politechniki Slaskiej - Matematyka-Fizyka. 1994. № 71. C. 217-224.

4. Kovaliukh N., Skripkin V., Van Der Plicht J. 14C Cycle in the Hot Zone around

Chornobyl. Radiocarbon. 1997. № 40 (1). P. 391-397. doi:10.1017/ S0033822200018270

5. Skripkin V., Kovaliukh N. Recent Developments in the Procedures Used at the SSCER Laboratory for the Routine Preparation of Lithium Carbide. Radiocarbon. 1997.

№ 40 (1). P. 211-214.

doi:10.1017/

S0033822200018063

6. Buzinnyi M., Skripkin V. Newly Designed 0.8-ML Teflon® Vial for Microvolume Radiocarbon Dating. Radiocarbon. 1995. № 37 (2). P. 743-747. doi:10.1017/S003382220003 1283

REFERENCES 1. Buzinnyi M., Likhtarev I., Los' I., Talerko N. and Tsigankov N. Radiocarbon. 1997 ; 40 (1) : 373-379. doi:10.1017/S003382220001 8257

2. Buzinnyi M. Radiocarbon. 2006 ; 48 (3) : 451-458. doi:10.1017/ S003382220003887X

3. Kovalyukh N.N., Skripkin V.V., Sobotovich E.V. et al. Radiocarbon of Accidental Release of Chornobyl NPP in Annual Tree Rings. Zeszyty Naukowe Politechniki Slaskiej -Matematyka-Fizyka. 1994 ; 71 : 217-224 (in Russian).

4. Kovaliukh N., Skripkin V. and Van Der Plicht J. Radiocarbon. 1997 ; 40 (1) : 391-397. doi:10.1017/ S0033822200018270

5. Skripkin V. and Kovaliukh N. Radiocarbon. 1997 ; 40 (1) : 211-214. doi:10.1017/S003382220001 8063

6. Buzinnyi M. and Skripkin V. Radiocarbon. 1995 ; 37 (2) : 743-747. doi:10.1017/S003382220003 1283

Hagitiwno go pega^i'i 17.05.2018

№ 3 2018 Environment & Health 74

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