Opportunities and perspectives of agricultural development in radiation-polluted territories

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Opportunities and perspectives of agricultural development in radiation-polluted territories

О.О. Teteruk

На основі аналізу результатів досліджень та наукових публікацій вітчизняних і зарубіжних вчених обґрунтовано можливості та перспективи розвитку сільського господарства на радіо-активно забруднених територіях Полісся. Розглянуто значення питомої активності ¹³⁷Cs та встановлено, що усім культурам властиве підвищене його накопичення.

Ключові слова: цезій-137, питома активність, сільськогосподарські культури, радіоактивне забруднення, територія.

The main radionuclides that determine the radiation state of contaminated area are ¹³⁷Cs and ⁹⁰Sr [1] at the later stage of the Chornobyl accident. In human body, they get along with food: as a result of their transition from soil to plants [2, 3].

The amount of radioactive substances re-leased from the soil in the plant depends on the contamination of the territory, the type of soil, the supply of its elements of the feed, the type of its cultivation, the type of plant, weather con-ditions, the intensity of biomass accumulation. Taking into account these factors it is of great practical importance in predicting the accumula-tion of radionuclides [4].

Polissya area has a significant potential for the production of plant material, therefore, an extremely important problem in Zhytomyr region has been caused by the provision of ra-dio-ecological safety of the population living in contaminated areas and the development of measures to reduce the accumulation of radio-nuclides in crop production [1].

The experience of past years has shown that in the area of radioactive contamination, a complete cessation of economic activity is unrea-sonable. This in no way contributes to the return of contaminated areas to the pre-accident state. And even vice versa: human non-interference with these processes can in many cases lead to secondary negative radiological consequences (fires, uncontrolled proliferation of quarantine weeds and plant diseases), which require urgent decisions due to their danger to the surrounding rural areas [5].

The technologies of cultivating crops on radioactive contaminated lands are devoted to the work of the following scientists: Hudkov I.M., Pristor B.I., Vorona L.I., Kochyk H.M., Storo- zhuk V.V., Dankevych Ye.M., Kovalov V.B., Mar- tyniuk H.O., Bondar O.I., Dutov O.I., Mashkov O.A., Derebon I.Yu. and others.

This leads to the search for new complexes of measures aimed at obtaining crop and livestock products that meet the radiological standards and the safe use of agrocenoses in radioactive contaminated areas [6].

One such measure is the species and va-riety selection of crops that least accumulate radionuclides [7]. This makes it possible to adapt agriculture, even at densities of contaminated areas that do not meet the recommendations. This is especially true in agricultural lands with high variability of radioactive contamination. radioactive substance soil accumulation

In addition, this method is conventionally the most economically advantageous, since it does not require additional expenses for reclamation measures aimed at reducing the specific activity of radionuclides in products.

Among the plants that people grow for the sake of obtaining beneficial fruits and seeds, en-ergy and oil crops occupy an important place.

The rapid exhaustion of energy resources reserves prompts society to re-evaluate the en-ergy potential of agro-crops, to change the at-titude towards biomass and phyto-energy as a whole. An important argument for the develop-ment of green energy is that energy crops can grow on non-fertile soils, as well as on land that is withdrawn from agricultural use, and to create a large amount of biomass under such conditions. That is, they do not create competition for basic food crops [3].

The sowing area of oilseed crops in our state reaches 1.8 million hectares [4]. Consump-tion of vegetable fats per capita doubled. In the countries of the European Community, 41 kg of oil per year are consumed per person per year, on average in the world -- 15.7 kg. An impor-tant condition for increasing the production of oilseeds is the sharp increase in the demand for vegetable oils. As a nutrition product, according to the biomedical assessment, they are much more useful and safer for the human body than animal fats [5].

The purpose of researches will be analysis of possibilities and perspectives of use of radio-actively polluted areas.

Methods of researches: field (radiometric measurements and sampling), laboratory (ra-diochemical analysis, gamma- and beta-spect-rometry, atomic absorption spectrophotometry, potentiometry, titrimetry), methods of mathe-matical statistics, cartographic.

The research was conducted in stationary field experiments, located near Khrystynivka village on turf-podzolic sandy soils with a pol-lution density of 925-1036 kBq/SQM.

The accounting area of each site on which the particular version of the experiment is conducted is 10.15 m², the repetition of the four-time.

Breakdown of the experimental plot, field work on the experimental site, fertilization, soil cultivation, sowing and planting, plant care and experiment, crop accounting was performed ac-cording to generally accepted methods. Agro- technical cultivation is generally accepted for Polissya area.

Agrometeorological conditions of the re-ported year were contrasting both by the amount of precipitation and temperature regime. Janu-ary was cold: the average temperature of the air was -5,0°C (at a rate of -3,6°C) and low in snow. February -- on the contrary, the temperature regime is within the normal range, and by the amount of precipitation exceeded the multi-year indicators by 1.7 times.

March was marked as too warm (5,6°C vs. average-long-term 2,3°C) and rainy -- 42% more than normal.

During the spring and summer periods rainfall fell within the normal range, although in the summer months rains fell in the form of short-term showers, which, due to one-sided regulation of moisture, rapidly descended from the arable layer under conditions of flushing type of drained soils. The exception was June month, when the amount of precipitation was only 29% of the average multi-year indicators, while SCC was only 0.35 against the norm -- 1.2.

The temperature regime during the grow-ing season was within normal limits, but at the beginning of the restoration of the winter crops vegetation, abnormal deviations were observed, in particular, night frostbite was recorded. Thus, during April 17-21, the air temperature dropped to -1.3-3.0°C; and on the 10th and 11th of May the night air temperature was -0.9 and -0.1°С.

Subsequently, the weather conditions con-tributed to the active formation of generative organs of crops.

The distribution of rainfall during the growing season was uneven. So, if the beginning of the growing season was characterized by an even distribution of precipitation over decades, in the second and third decades of July and the first decade of August fell the largest amount of precipitation, then the middle of August was marked by aridity.

Beginning of the growing season, namely in April, there was an abnormally low temperature regime of air that suspended the development of plants.

Since stationary research was carried out on a territory that was withdrawn from agricul-tural use in 1986 and year, data on the type of soil and its main agrochemical characteristics were absent. Therefore, agrochemical analysis of soils was carried out before laying experiments.

As a result of laboratory agrochemical stu-dies for establishing the basic agrochemical cha-racteristics of the studied soils, it has been found that they have such indicators:

1) physical properties of the soil (layer of 0-20 cm): specific mass -- 2.62 g/cm³; density (volume mass) -- 1.46 g/cm3; lowest moisture content -- 15.33%; total water capacity -- 27,65%; moisture reserves with the least moisture con-tent -- 23,42%; available moisture reserves -- 20.47%; the content of physical clay -- 12,21%;

2) chemical properties: the content of hu-mus (0-10 cm layer of soil) -- 1,79%; pH of the salt -- 6.23; saturation basics -- 4,54%; hydro-lytic acidity -- 1,6; the content of moving alumi-num -- 0,23 mg/100 g of soil; calcium content --

0. 87 mg/100 g of soil; phosphorus content -- 17,36 mg/100 g of soil; Potassium content -- 1.78 mg/100 g of soil.

According to physical and chemical proper-ties, the soil fully corresponds to the most com-mon soddy podzolic soils in Polissya area.

In order to determine the radiological cha-racteristics of the soil, the distribution of the spe-cific activity of ¹³⁷Cs on the soil profile (fig. 1).

It is evident from the data that the larg-est specific activity of ¹³⁷Cs is concentrated in a layer of soil 0 ... 10 and 0 ... 20 cm, which is af-fected by 45.3 and 40% of the activity of ¹³⁷Cs. In the layer 20 ... 30 cm concentrated only 12% of the total specific activity of ¹³⁷Cs. In layers of 30 ... 60 cm, the activity of ¹³⁷Cs is less than one percent, and only traces are observed in the soil layer from 60 to 100 cm.

Thus, we can conclude that this type of soil is characterized by a high sorption ability, which characterizes the weak migration of ¹³⁷Cs by soil profile. The greatest negative factor in this is the concentration of radionuclide in the upper -- arable layer of soil, making it the most accessible to the root system of plants.

Therefore, particular attention should be paid to the morphological features of plants, and especially to the depth of occurrence of roots, and the type of root system, which determines the intensity of absorption of ¹³⁷Cs.

Hence the important factor is the biological features of plants, namely, species and variety characteristics. So the plant's need for potassium determines more accumulation of its analogue -- cesium. In addition, the input of radionuclides into plants depends on the distribution of the root system in the soil, their productivity, the length of the growing season, and so on. As a result of radiological studies (on average a few years), the following data were obtained (Table 1).

The highest specific activity is observed in amaranth and acanthate (more than 1120 Bq/kg). The smallest is in buckwheat and sorghum (up to 586 Bq/kg).

The same situation is typical for fertilizers ^K90^R60.

However, it is in these plants that the lar-gest percentage of reduction in specific activity is observed. The ranked series has the following form: Sugery Sorghum «Botanichnyi (3.2%), Suripytsia Sunflower (3.8%), Sylphia (4.4%), Mis- kanthus (5.3%), Topinambur (5.8%) %), Siverska Soya (8.6%), Soya «Amerikanka» (9.2%), Vorskla Soya (10.1%), Rumekes OK-2 (10.7%), Amaranth «Kremovy» (11.4%), Shchavnat «Binar» (12.1%), Amaranth «Carmen» (12.8%) and Amaranth «Hrozynskyi» (13.5 %).

However, even these indicators do not guarantee the receipt of products that are not contaminated with radionuclides in excess of the norm. What makes them look for options for their re-processing.

Determination of the specific activity of ¹³⁷Cs of cultures suggests that these cultures

Table 1 Unit activity of ¹³⁷Cs in plants, Bq/kg

typically have an increased accumulation of ra-dionuclides.

All crops other than amaranth and gaogan- bo, taking into account allowable levels of ¹³⁷Cs and ⁹⁰Sr radionuclide content in livestock and crop material, are favorable for growing under conditions of radioactive contamination of ter-ritories in order to ensure production of guaran-teed quality of 600 Bq/kg. The following are unsuitable for feeding animals, but there is the possibility of using them on siderate and raw materials for oil and biofuel production. In ad-dition, it is the amaranth and the acanthus that best remove radionuclides from the soil, which, in turn, accelerates its purification for full use.

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