Soleros — natural absorbers of mineral salts



Saline soils appear in places with a hot, arid and windy type of climate. Every year the area of their distribution increases, and the rehabilitation of saline soils becomes more expensive and can reach several decades of years. The considerable distribution of saline soils on the territory of our country and a significant decrease in the productivity of crops in these conditions make it necessary to evaluate the degree of salt tolerance of plants. The latter is of great importance for breeding, introduction and cultivation technology. A new way of saline soils rehabilitation is also needed.

No plant can grow on soil covered with salt, solonchaks have always been a symbol of a barren, uninhabited land. When the ruler of the Holy Roman Empire Frederick Barbarossa destroyed in 1155 Milan in Italy, he ordered to sprinkle the ruins of the defeated city with salt as a sign of his complete annihilation.

Nowadays in all irrigated areas of the world the soil becomes more salty. Salinization of soils leads to a fall in the yield of agricultural crops. In this regard, the issue of salt tolerance of plants is becoming more urgent.

Salt-resistance of plants is the ability of plants to resist salinization, without reducing the intensity of the flow of basic physiological processes.

It has been suggested that plants, capable of accumulating mineral salts, can purify the soil of their excess.

We want to find out if the salt can collect mineral salts and how much.

For this we should:

– to determine the qualitative and quantitative chemical composition of the water selected in the reservoirs located near the place of growth of the investigated soleros;

– to determine the qualitative and quantitative chemical composition of water extracts from coastal plants and soils;

– carry out a comparative analysis of data on the presence of chloride ions and calcium and magnesium ions in water, soil and plants.

The objects of the study were three different biogeocenoses located in the southern part of the Astrakhan region, each of which included a land area, a reservoir and coastal vegetation.

Water reservoirs of various origin, water regime and salt composition were selected: Protochny of the Liman village of the Astrakhan region; IlmenGalya in the area with. ZarechnyiLimanskiy district of the Astrakhan region (upper and lower current).

Ilmen — is a small reed overgrown lakeso in the southeast of the European part of Russia; it is usually located in the deltas of large rivers (Volga, Ural, etc.) and formed from their extended branches or estuaries. The water channel is an artificial water artery designed to reduce water routes or to divert water flow.

In the course of the study, we used natural water from the studied reservoirs; Upper and lower horizons of coastal soil; Roots and leaves of coastal plants. Samples were selected in October 2014 and 2015. Soil was selected from two horizons in each of the cases. Plants to search for a cumulative organ were separated and the roots and leaves were examined separately.

To determine the qualitative composition and content of the substances found in it, water extracts of plants and soil extracts were prepared. Stems and roots of plants, as well as soil from the upper and lower horizons from different reservoirs were investigated separately.

Preparation of water extracts of the plant: washed, dried and finely chopped roots and leaves of the solerosa suspended on a techno-chemical scale, placed in a flat bottom flask, filled with distilled water with respect to: 2: 3 roots, 1: 10 leaves and aged for 7 days.

Preparation of soil extracts: 10 g of dried and sifted earth suspended on a technochemical scale were placed in a flat bottom flask, 100 ml of distilled water were added and aged for 7 days. The prepared solutions were filtered and analyzed.

The presence of cations I-III, V and VI of analytical groups in the solutions studied was determined by systematic analysis. The cations of the IV analytical group were determined by fractional analysis. The anions were determined with the aid of qualitative reactions by a fractional method.

The quantitative content of calcium and magnesium ions was determined by the complexometric method. A solution of Trilon B was prepared by dissolving a sample of dry matter in distilled water. The concentration of Trilon B solution was established by titrating it with a standard magnesium sulfate solution prepared from fixanal. Titrated until the transition of the red color of the erochrome black to blue.

Calcium ions were determined by adding to 10 ml of a solution of 6–8 ml of 2N hydrochloric acid. Solution of sodium hydroxide to pH 12, introducing 1 micro spatula indicator and titrating solution Trilon B before the transition of pink color in purple-lilac (violet).

For the detection of magnesium ions to 10 ml of the solution, 5–7 ml of the buffer mixture was added, introducing 1 microliter of the indicator — chromogen — and titrating with Trilon B solution until the pink color shifted to blue.

The concentration of chloride ions was determined by argentometric titration (according to the Mor method). To determine the concentration of chloride ions, 1 ml of a 10 % solution of K2CrO4 was poured into 10 ml of the test solution and titrated with a silver nitrate solution until a brick-red precipitate appeared.

In all solutions cations: Na⁺, K⁺, Ca²⁺, Mg²⁺, as well as anions: Cl^-, SO4^2- were found. In plants and soil near the upper stream, lead ions, as well as nitrate ions, were found in samples of 2015. The results of the quantitative analysis are presented in Tables 1, 2.

Table 1

The content of various ions in the investigated objects

Subject of study	Ions of calcium	Magnesium ions	Chloride ions
The soil
Channel, lower horizon	0.00375	0.00279	0.0037
Channel, upper horizon	0.011	0.01	0.0111
Ilmen, lower course, lower horizon	0.0009	0.00135	0.0063
Ilmen, lower course, upper horizon	0.0024	0.00248	0.0069
Ilmen, upper course, lower horizon	0,000825	0,0021	0,0094
Ilmen, upper course, upper horizon	0,0057	0,0064	0,0095

Table 2

The content of various ions in the investigated sites (2015)

Subject of study	Ions of calcium	Magnesium ions	Chloride ions
Plant roots
Channel	0,00165	0,0137	0,0146
Ilmen, the lower course	0,0065	0,0144	0,028
Ilmen, the upper current	0,00476	0,0156	0,067
Stems and leaves of plants
Channel	0,006	0,0146	0,086
Ilmen, lower current	0,0036	0,0113	0,121
Ilmen, the upper course	0.0047	0.009	0.126
Water
	Calcium ions,G / ml	Magnesium ions,G / ml	Chloride ions, g / ml
Channel	0.0018	0.002	0.004
Ilmen	0.0014	0.002	0.004
The soil
Channel, upper horizon	0,033	0,04896	0,01065
Ilmen, lower course, lower horizon	0.00276	0.01158	0.0461358
Ilmen, lower course, upper horizon	0.0168	0.0025	0.0093
Ilmen, upper course, lower horizon	0.0168	0.0372	0.01733
Ilmen, upper course, upper horizon	0.0207	0.012084	0.01065
Plant
Channel	0.03018	0.1506	0.0189
Ilmen, the lower current	0.02154	0.0618	0.01207
Ilmen, the upper current	0.0324	0.042	0.058

As a result of our experiments, we came to the conclusion that

– the best studied soleros absorb chlorine compounds, which were found in large quantities in the leaves of the plant;

– Mg²⁺ ions are evenly distributed throughout the plant, that is, the amount of magnesium in the roots and leaves of the plant is the same, but its content in plants exceeds values in soil extracts and in water;

– the content of calcium in plants does not exceed its content in the soil;

– The presence of lead ions and nitrate ions in samples can be associated with anthropogenic influence.

Thus, it has been clarified that salt-sorrows absorb only some types of salts, and their use as a natural cleaner of saline soil can be considered only with respect to chloride ions.

References:

1. AN Gennadiev, MA Glazovskaya Geography of Soils with the Basics of Soil Science. Moscow: Higher School. 2005.
2. Klyshev L. K. Biochemical and molecular aspects of the study of salt tolerance of plants. // Problems of salt tolerance of plants, — 1989., — 195 p.
3. Method of complexometry: Methodological guide to the performance of laboratory work on the discipline «Analytical Chemistry» / Starkova NN, Dzhangralieva AA — Astrakhan. State. Tech. University, 2006. — 6 p.
4. Methods of deposition. Argentometry: Methodological guidelines for performing laboratory work on the discipline «Analytical Chemistry» / Shavel II. — Astrakhan. State. Tech. University, 2006. — 7 with.
5. Reactions of ion exchange. Oxidation-reduction reactions in qualitative analysis (anions): Methodological guidelines for performing laboratory work on the discipline «Analytical Chemistry» / Starkova N. N., Ogorodnikova N. P. — Astrakhan. Gos. Tech. University, 2011. — 4 with.
6. Particular reactions of cations of Groups I-III: Methodological guidelines for performing laboratory work on the course «Analytical Chemistry» / Kalambetova LS — Astrakhan. State. Tech. University, 2006. — 7 with.