Method for cleaning of soil from technogenic contaminants

FIELD: agriculture, in particular, environment protection, more particular, reduction of 137Cs level in soil.

SUBSTANCE: method involves growing accumulating plants such as lentils and Jerusalem artichoke on contaminated soil during three vegetation periods; alienating the entire plant biomass from soil at the end of vegetation period; determining soil cleaning extent from formula: Cη=(Ca-Cs/Ca)*100(%), where Cη is extent of cleaning soil; Ca is level of 137Cs in soil before planting of said accumulating plants; Cs is level of 137Cs in soil after withdrawal of the entire plant biomass from soil at the end of vegetation period.

EFFECT: reduced specific activity of 137Cs in soil, increased efficiency in removal of radio nuclides and obtaining of ecologically clean plant products, reduced possibility of external and internal radiation of people.

2 tbl

 

The invention relates to agriculture, the environment, namely, decrease in soil specific activity137Cs in the soil.

A known method of reducing137Cs in the soil at the turn of contaminated soil by deep plowing [1].

The disadvantage of this method is the closure of contaminated topsoil less polluted bottom layer. When this contaminated soil and it contained radioactive cesium remain available to the root system of most plants.

The closest in technical essence of the present invention is a method of reducing the concentration of heavy metals (TM) in the soil by growing canola plants, which are able to accumulate in their biomass TM [2]. By this method the contaminated soil TM, growing rape. At the end of the growing season remove all biomass plants and roots and aerial organs. Exclusion of plant biomass from the soil contributes to reduction in soil such TM as cadmium, cobalt, lead, Nickel, and iron.

The disadvantage of this method is that it does not provide an effective reduction in the soil is the main dose-forming radionuclides -137Cs.

The challenge which seeks the invention consists in reducing the specific activity137Cs in the soil.

It has reached what is fact, in the method of cleaning soil from anthropogenic pollution, which consists in growing on contaminated soil-plant storage and the disposal of the entire biomass of the plants from the soil at the end of the vegetation period, in contrast to the prototype of the soil clear of137Cs, as plants drives use lentils or Jerusalem artichoke, which is grown during three growing seasons in a row, and the degree of purification of the soil is determined by the formula:

Withη=(SN-SP/SN)·100 (%),

whereη - the degree of purification of the soil,

SN - level137Cs in the soil before planting,

SP - level137Cs in the soil after removal of all biomass plants from the soil at the end of vegetation.

The method is as follows. In radioactively contaminated soil in the space of three growing seasons in a row grown plants can accumulate137Cs - lentils and artichokes. At the end of each growing season whole plant biomass is alienated from the soil. The maximum reduction level137Cs occurs after three years of cultivation (table 1).

Table 1

Reducing the specific activity137Cs in soil (% of the original number)
Option the Timing of cultivation (years)
1234
Control (without plants)0-2,51,1-12,73,3-26,34,1-27,8
Soil after rape (prototype)2,2-2,525,7-26,026,7 is 27.227,1 of 36.5
The soil after Jerusalem artichoke10,8-21,323,0-25,539,6-42,722,2-47,8
Soil after lentils2,6-4,917,7 is 29.834,6-47,322,5-42,9

In the soil after growing Jerusalem artichoke level137Cs decreased after three years, 39,6-42.7 percent, after the lentils by 34.6-47,3%. In the soil after rape during this period the level137Cs decreased 1.3-1.7 times less. While extending the cultivation of plants up to 4 years reducing137Cs in the soil, has not changed.

The degree of purification of the soil after cultivation of plants changes as follows (table 2).

Table 2

The degree of purification of the soil (%, min-max)
OptionsThe timing of sampling
1234
0-2,50.1 to about 7.60,9-12,90,1-2,1
Soil after rape (prototype)2,2-2,52,2-2,800,0-1,00,0 is 21.2
The soil after Jerusalem artichoke10,8-21,3of 12.6 and 14.619,7 is 21.214,8-16,7
Soil after lentils2,6-4,92,7-9,112,8-20,6the 6.9 17.2

The maximum degree of cleaning soils observed in the variants with Jerusalem artichoke and lentils after the third term cultivation of plants.

Examples of the calculation of the degree of purification of the soil (for example, lentils):

The first term cultivation - level137Cs in the soil before planting CH=210,4-977,8 Bq/kg Level137Cs in the soil after removal of all biomass plants from the soil at the end of the vegetation period SP=200,1-952,2 Bq/kg

The degree of purification of the soil Withη=(977,8-952,2)/977,8·100=2,6% (minimum value); Withη=(210,4-200,1)/210,4·100=4.9 per cent (the maximum value).

The second term cultivation - level137Cs in the soil before planting CH=190,4-705,8 Bq/kg

Level137Cs in the soil after removal of all biomass plants from the soil at the end of the vegetation period SP=173,1-686,7 Bq/kg

The degree of purification of the soil Withη=(705,8-b,7)/705,8·100=2,7% (minimum value); Withη=(190,4-173,1)/190,4·100=9.1% of (m is kimalee value).

The third term cultivation - level137Cs in the soil before planting CH=158,0-643,1 Bq/kg

Level137Cs in the soil after removal of all biomass plants from the soil at the end of the vegetation period SP=137,7-510,3 Bq/kg

The degree of purification of the soil Withη=(643,1-510,3)/643,1·100=20,6% (maximum value); Withη=(158,0-137,7)/158,0·100=12.8 per cent (the minimum value).

Fourth term cultivation - level137Cs in the soil before planting CH=175,3-674,0 Bq/kg

Level137Cs in the soil after removal of all biomass plants from the soil at the end of the vegetation period SP=163,2-558,1 Bq/kg

The degree of purification of the soil Withη=(674,0-558,1)/674,0·100=17,2% (maximum value); Withη=(175,3-163,2)/175,3·100==6,9% (minimum value).

This method can reduce the specific activity137Cs in the soil, thereby removing radionuclides, gives the opportunity to obtain ecologically pure plant products, to reduce external and internal exposure of people.

Sources of information

1. Guide to farming in conditions of radioactive contamination of the territory of the RSFSR, the Ukrainian SSR and the Byelorussian SSR for the period 1988-1990 gg, M: Granitite, 1998, 41 S.

2. Ushamba, Rob. The use of plants to clean soil from anthropogenic pollutants - Lipetsk: LGTU // Ecology of the Russian Federation, No. 1, 1998 (the prototype).

SPO is about cleaning soil from anthropogenic pollutants, consisting growing on contaminated soil-plant storage and the disposal of the entire biomass of the plants from the soil at the end of the vegetation period, characterized in that the soil clear of137Cs, as plants drives use lentils or Jerusalem artichoke, which is grown during three growing seasons in a row, and the degree of purification of the soil is determined by the formula

Withη=(SN-SP/SN)·100 (%),

whereη - the degree of purification of the soil;

SN - level137Cs in the soil before planting;

SP - level137Cs in the soil after removal of all biomass plants from the soil at the end of vegetation.



 

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