Файл: Исследование суточных вариаций поровой активности радона в поверхностных грунтах удк 550. 42 546. 296 551. 51.docx

1 Chapter

1. Origin and properties of radon

   1. Physical properties of radon isotopes. Radioactive families

Radon normal conditions is yourself radioactive colorless inert gas without stable isotopes. High concentration radon air dangerous For life and health person. Physical propertiesradon indicated below table 1.
Table 1. Physical properties radon

Temperature boiling	- 62 °C
Temperature melting	- 71 °C
Density radon in gaseous state at normal conditions	9.727 kg / m 3
Radius atom	214 pm
Energy ionization	10.74 eV

Radon is 55 times heavier than helium and 7.6 times heavier than air. [1] A large amount of radon and helium dissipates in the water column and the earth. The main amount of radon is concentrated in the upper layers of the earth's crust, which is about 115 tons. The amount of radon in the atmosphere is much less, about 4 kg. Almost zero radon content in the air and ice of Antarctica. [2-4]

Radioactive gas-radon is a decay product of a number of natural radioactive families of uranium and thorium. The most stable radionuclide in this family is ???????? 222 ( 1/2 = 3.8235 days) . uranium family

???? 235 ( 1/2 \u003d 7.13 108 years) includes ???????? 219 ( ???? 1/2

\u003d 3.96 s) , it is called actinon ( An ). The thorium family

????ℎ 232 ( 1/2 = 1.41 1010 years) includes ???????? 220( ???? 1/2 = 55.6 s) , which is called thoron ( Tn ). Ultimately, in the process of decay of the chain of these radioactive families, a stable radioisotope of lead is formed, the serial number of which is 82. In the uranium family it is ???????? 206, in the thorium family it is ???????? 208 , in the anemone family it is ???????? 207 . [1-7]



Figure 1. Radon radioactive family chain

2. Decay products of radon. Physical properties of radon

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When emitting an α-particle, radon radioisotopes change their state of aggregation and turn from a group of inert gases into solid radioactive isotopes. [8-10] During the decay of radon, isotopes are formed, such as polonium, bismuth, thallium, and lead. The stable isotope of lead is the last link in the chain of transformations of radon isotopes.


Figure 2. Chains of radioactive decay of radon isotopes

Within the framework of radioecology and radiation safety, when considering the resulting daughter products of radon decay, one can limit oneself to a certain part of the chain containing only long-lived isotopes. In the chain ???????? 222 is ???????? 210 , with a half-life of 22 years. ???????? 210 fails to achieve an equilibrium concentration in the atmosphere, which is why it and the subsequent daughter products of the decay of the chain can be safely neglected.

During the decay of radon, metals are formed that are in a free state for a short time. Metals interact with non-radioactive aerosols that are constantly present in the atmosphere, such as particulate dust, fog droplets, and so on. When metals formed during the decay of radon interact with non-radioactive aerosols, radioactive aerosols are formed. Thus, the linear size of the daughter products of radon decay increases several times. [11-12]

The equivalent volumetric equilibrium activity of radon (EVEA) for a nonequilibrium mixture of short-lived progeny decay products in air is the volumetric activity of radon that is in equilibrium with its progeny decay products and has the same amount of latent energy as this nonequilibrium mixture. [11]

EROA ???????? = ???? ∗ OA ???????? = 0.5161 ???????????? + 0.3793 ???????????? + 0.1046 , (1)

where ???????????? , ???????????? , ???????????? – volumetric activities of short-lived radon decay products ???????? 218, ???????? 214 and ???????? 214 , respectively, Bq/m ³ ; F is the balance coefficient, the value of which is from 0 to 1.

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Areas applications quantities density flow radon

Currently, the values of the radon flux density are being actively studied. both in theory and in practice to find solutions to a number of different tasks and problems next areas specified below:

Geophysics: seismology - the science forecasting changes stress- strain states bowels terrestrial bark, earthquakes; breath soil.

Geophysics: atmospheric physics, climatology is a science that deals with study and evaluation influence radon, located on earth, on electrical properties top layers atmosphere, study trajectories movements air wt.

Radioe cology. Geoecology. radiation biology - the science, evaluating radiation danger For population from estimates radon - dangers on territory, residential buildings.

1. Radioecology. Grade radon hazard territories and buildings

   1. Radon hazard territories

The density of the radon flux on the earth's surface serves as a criterion for definition potential radon - dangers territories in Russian federation, established rules OSPORB-99. [13] According to sanitary requirements established on territory RF [14], average meaning density

flow radon With surfaces land on territory, destinations under construction, Not must exceed 80 mBq ^⁄ m ² s. Territory under educational institutions meaning density flow radon should not be 40 mBq ^⁄ m ² s. The main condition for the delivery of residential premises so that the average annual equilibrium volumetric activity of radon in air Not exceeded 100 Bq/m ³ .[15]

2. Radon hazard buildings

In air residential and public buildings present radon, which is one of the main components of air pollution, and also counts significant factor risk for health population. By

"Norms radiation security" content voluminous activity radon not must exceed 200 Bq/ ^m3 , For residential buildings. [16]

2. Forecast earthquakes and volcanic activity

One from weighty tasks geophysics counts search reliable methods short-term forecasting earthquakes and eruptionsvolcanoes. An increase in stresses in soil gases in the air at the surface earth. [20,21] Monitoring characteristics radon fields

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at borders systems

"lithosphere-atmosphere" allows judge processes, ongoing on earth's crust.

To increase the sensitivity of the radon forecasting method earthquakes try conduct monitoring in districts, where present deep highly active sources radon (breeds with high content uranium; zones tectonic faults in terrestrial bark) For increase amplitude anomalous bursts.

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Climatology. Radon - as a tracer of air exchangeprocesses

Radon long time used in quality tracks, which followbehind the air masses vertically and horizontally. (transcontinentalscale) direction. [22-29] In addition to radon, for the study of various dynamic atmospheric processes and refinement of the global chemical models transfer, apply other radionuclides - thoron , ???????? ²¹² , ???????? ²¹⁰ ,

???????? ⁷ , ???????? ¹⁰ and ???????? ¹⁴ . From them radionuclides ???????? ²¹⁰ , ???????? ⁷ , ???????? ¹⁰ , which are joining With non-radioactive aerosols and are useful at studying sedimentation because of precipitation rain and snow. Monitoring these natural radionuclides on a large scale are needed to study global changes climate and forecasting. For solutions the aforementioned tasks necessary know behavior and spatial distribution of RFD from the surface of the earth. However, existing knowledge about spatial (over all continents) and temporal variability of the value RFD is still not enough. Construction of detailed maps about RFD based on content data ???? ²³⁸ ( Ra²²⁶ ) requires knowledge of many parameters, such as How type and humidity soil, temperature (or vertical gradient temperature in system priming atmosphere), intensity atmospheric precipitation and etc. This stimulates new experimental research speakers RFD simultaneously With improvement methods measurements.

In addition, radon is a useful tool in determiningcoefficients diffusion gases and aerosols IN surface atmosphere. [30,31]

More one application radon found in quality indicatorvertical sustainability bottom atmosphere and thickness layer convective mixing. [32,33]

2. Chapter

   1. Indirect methods - modeling RFD By changed VA radon in surface soils

Way By definition density flow radon founded on models diffusion-advective transfer and two values volumetric activity radon, measured on different depths. The method was field tested with excellent results. Gradedensity radon flux takes into account influence climatic conditions.

Distinctive trait given method

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