MICROCOMPONENT COMPOSITION OF PEATS AND PEAT WATERS OF THE OB, TAGAN, AND SOUTHERN PART OF THE VASYUGAN PEAT DEPOSITS

N. M. RASSKAZOV, R. S. SOLODNIKOVA, M. R. GOLOVINA

The study of the microcomponent composition of peats and peat waters of Tomsk Oblast is being carried out by Tomsk Polytechnic Institute and the Giprotorfrazvedka Institute in order to clarify the process of formation of peat deposits.

The results of these investigations can be used for various practical purposes, including assessment of the balneological properties of waters and peats, use of the latter as mineral fertilizers, and also for resolving questions concerning the genesis of peat deposits and the conditions of their development.

In the course of field work, hydrogeological observations were conducted, the chemical composition of waters was studied, and samples of water and peat were taken for various types of determinations in the southern, eastern, and northern parts of the Vasyugan deposits, as well as in the Ob, Small Tagan, and Large Tagan deposits. At the same time, the composition of atmospheric precipitation was investigated.

In peats and waters, both the total content of microcomponents and the quantities assimilable by plants were determined (according to the method of Ya. V. Peive).

Different types of peat deposits are not equivalent in pH value, which exerts a decisive influence on the migration of chemical elements. As a rule, raised bog massifs are characterized by an acidic environment (pH up to 3.5), while lowland massifs are weakly acidic, neutral, and slightly alkaline (Table 1). As the investigations of T. V. Drozdova (1964) and other authors show, the acid–alkaline properties of peats and peat waters depend mainly on the type of organic acids and their compounds (humic and fulvic acids) contained in them. The microcomponents contained in bog waters form with them various organometallic compounds, whose transfer into solution depends to a considerable degree on the pH value.

Experimental work carried out in the problem geological laboratory of TPI showed that humic acids actively form complex compounds with copper, lead, zirconium, beryllium, chromium, and, less actively, with zinc, cobalt, nickel, and silver. On the basis of these same studies it may be concluded that many organometallic compounds are characterized by an increase in solubility with rising pH of the solutions.

Of great importance for the question under consideration is the study of iron gels widely distributed in peat bogs, since subseq—

carry on their surface a large complex of microcomponents (manganese, cobalt, nickel, etc.). The latter are precipitated by ferric iron gels when natural waters enter an oxidizing environment.

Fig. 1. Electron micrographs of natural humates and manganese humate (for comparison): a, b — manganese humates isolated from travertines of a lowland bog in the city of Tomsk; c — synthesized manganese humate.

In addition, in the lowland bogs of the Tomsk area, travertines are often encountered; these are also enriched in microcomponents. Here, in addition to calcium, molybdenum, manganese, and phosphorus—needed by plants—occur in elevated amounts. In the study of Tomsk travertines, natural humic compounds of metals were found in them, shown in part in the photograph (Fig. 1).

Comparing images of natural humates of metals isolated from travertines with images of synthesized humates of metals, one can

assign them to manganese humate (Fig. 1, c). But since in travertines there is also iron in significant amounts, which, in interaction with humic acids, forms black iron humate with characteristic dense, leaf-shaped outlines, the photographs of natural humates have the form of particles of manganese humate of a darker color. Electron-microscopic photographs of the humates of many metals, in the form of the arrangement of the particles, resemble dendrites of colloidal origin.

The study of the features of element migration and the determination of their contents in peats were carried out on different types of peat deposits.

In the Tomsk area, in 1963, for this purpose B. I. Shestakov and L. A. Skripalshchikova surveyed the M. Taganskoe bog. In 1965 we began the study of microcomponents in the waters and peats of the B. Taganskoe lowland deposit. In chemical composition, the waters of the deposits are hydrocarbonate-calcium waters with a total mineralization of about 160 mg/l; pH varies from 5.2 to 7.6. A significant complex of microcomponents was found in the water, among which manganese and zinc predominate (Table 1).

In the peats of the M. Taganskoe deposit most microcomponents were found in amounts of thousandths and ten-thousandths of a percent (Table 1). The exception is manganese, whose average content is $\sim 0.1\%$.

For this deposit, the dependence of microcomponent contents on the type of peat and the degree of its decomposition was analyzed. The influence of the degree of decomposition is most clearly manifested (Table 2). With increasing decomposition, the frequency of occurrence increases, i.e., the overall average content of nickel, chromium, barium, strontium, and zirconium rises. This can apparently be explained by an increase in the dispersity and sorption capacity of peats with increasing degree of decomposition. At the same time, the content of humic and fulvic acids, which form various organometallic compounds with microcomponents, changes. At present, the study of this question is continuing.

Along one profile at the B. Taganskoe deposit, peat samples were taken at different depths to determine the amounts of microcomponents assimilated by plants.

Copper, zinc, and manganese were found in the analyzed samples. The results of the analysis show that the manganese content is elevated and varies from $4 \cdot 10^{-2}$ to $8 \cdot 10^{-3}$; the contents of copper and zinc are insignificant and fluctuate within the range from $1.8 \cdot 10^{-3}$ to $5 \cdot 10^{-5}\%$ (Table 3, B. Taganskoe bog).

The content of microcomponents was also determined in the waters and peats of the Ob lowland deposit.

In general chemical composition, the waters here are hydrocarbonate-calcium waters with a total mineralization of about 280 mg/l; in pH value they are neutral and weakly alkaline, and very rarely weakly acidic (Table 1).

Significant contents of calcium (about 10%) were established in the composition of the peats; of the microcomponents, manganese ($>1\%$), barium ($\sim 1\%$), and strontium ($\sim 0.2\%$) were found in elevated amounts. At the same time, in the waters of this deposit, in contrast to the peats, these elements were found in smaller amounts than in the waters of other deposits described. Along with this, they contain significant amounts of titanium, nickel, cobalt, and vanadium. It is possible that the enrichment of the peats in manganese, strontium, and barium is caused by the presence of elevated contents of iron gels, by the features of the acid–alkaline environment, and by the feeding of the bog.

Table 1

Average chemical composition of peats and waters of several peat bog massifs of Western Siberia

Note. The content of microcomponents in waters is in mg/l, in peats in percent.

Table 2

Comparison of microcomponent contents in various peat types depending on the degree of peat decomposition

Continuation of Table 2

Note. T—Tagan peat deposit.
V-s-v—eastern part of the Vasyugan peat deposit.
O—sedge peat.
D—woody peat.
S—sphagnum peat.
The botanical composition of the peat was determined by staff member of Tomsk State University G. T. Yasnopolskaya.

In determining in the peats of the Ob deposit, by the method of Ya. V. Peive (1959), the quantities of microcomponents assimilable by plants, it was established that at this deposit manganese occurs in relatively elevated amounts (Table 3).

In the southeastern part of Vasyugan, lowland and raised bog massifs were reconnoitered. Their hydrogeological features have so far been poorly clarified. The hydrogeochemical conditions of these types of bogs differ to a considerable degree and therefore are described separately below.

Lowland bogs are characterized (Table 1) by a weakly acidic medium (pH ~ 6.5), a bicarbonate–calcium composition of the waters with total mineralization of about 100 mg/l; oxidizability averages ~ 23 mg O₂/l, and the content of free CO₂ is ~ 20 mg/l. A large complex of microcomponents was found in the waters. The average content of most elements in the water is units and tenths of micrograms per liter; the greatest values were recorded for manganese—hundreds of micrograms per liter. The peats are characterized by a low content of zinc, lead, silver, copper, and vanadium; a certain increase is noted for manganese and cobalt. Determination in the peats of the quantities of microcomponents assimilable by plants showed that they contain assimilable manganese at 0.02–0.03% and assimilable zinc and copper at 0.0002–0.0005% (Table 1). A study of the dependence of the gross content of microcomponents on the botanical composition of the peat showed that in sedge peats many elements occur in somewhat larger quantities than in sphagnum and hypnum peats. This can be explained by the greater degree of decomposition of sedge peatlands. At the same percentage of decomposition, however, sphagnum peats contain equal or even somewhat greater quantities of microcomponents (Table 2). To clarify this question, special experimental studies must be carried out.

Analyzing the qualitative composition of micro- and macrocomponents and their quantity in the waters of lowland peatlands of the southeastern part of Vasyugan, one can readily note one of the most characteristic features of these bogs. It consists in the fact that the chemical composition of the peat waters of these deposits is intermediate between the composition of waters of typical raised and lowland massifs (Table 1). As is known, at present the generally accepted view is that raised bogs are fed by waters of atmospheric precipitation, whereas lowland bogs are fed by groundwaters. Meanwhile, the hydrogeochemical and hydrogeological study of the lowlands of southeastern Vasyugan makes it possible to conclude that their feeding is carried out mainly at the expense of atmospheric precipitation. In addition to the results of chemical analysis of the waters, this conclusion is confirmed by data on the geological structure of the region. The lowland peat here rests on laterally persistent clays up to 40 m thick. The clays contain a significant quantity of concretions of mineral salts, chiefly calcium, as A. Ya. Bronzov (1930) pointed out in his time. Under these conditions the formation of Vasyugan lowland peats may occur through excessive moistening of the territory by atmospheric precipitation and enrichment of the waters with mineral substances during dissolution of the concretions enclosed in the clays. To confirm this conclusion, experiments have been set up in the problem geological laboratory of TPI and the first positive results have been obtained. A final solution of this question is of considerable practical interest, since peatlands fed by atmospheric precipitation are much easier to develop than deposits with groundwater feeding.

On the other hand, in the north of Vasyugan and within the area of the latitudinal course of the Ob River, significant...

Table 3

Content of microelements accumulated in the peats of Tomsk Oblast*

* Analyses were carried out according to the method of Ya. V. Peive.

…extensive raised bog massifs that are fed predominantly by groundwater. The reclamation of such peatlands will present considerable difficulties. Therefore, delineating them—i.e., raised bogs with predominantly groundwater feeding—in the field is undoubtedly of considerable interest. The formation of these types of deposits, as shown by the results of hydrogeochemical studies, is due to the low mineralization of the groundwater in these regions. In a number of cases the magnitude of the latter only slightly exceeds the total mineralization of atmospheric precipitation, which may be explained by the considerable leaching of sandy deposits of glacial fluvioglacial origin. Thus, within the central part of the West Siberian Lowland, the formation of bog massifs differs to a significant degree from the analogous process in the European part of the USSR.

The raised bogs of Vasyugan are characterized by an acidic water reaction (pH 3.5–4.3), very low total mineralization (~20 mg/l), somewhat elevated oxidizability, and increased amounts of free CO₂ in the water. The peats of these bogs contain, in comparison with the lowlands of Vasyugan, somewhat larger amounts of copper, titanium, and lead; at the same time they are poor in manganese and strontium. In the peats of raised bogs the content of certain microcomponents assimilable by plants is closely related to the degree of their decomposition. Thus, in sedge peat, with a higher percentage of decomposition, the content of plant-assimilable manganese and copper is 2–3 times higher than in sphagnum peat. When considering the microcomponent composition of the waters of these bogs (Table 1), one may note a reduced content of silver and titanium in them, which is possibly associated with the low pH value, which adversely affects the solubility of their complex organic compounds.

Summarizing the data presented above, several general features may be noted in the chemical composition of the waters of the bog massifs examined. Their characteristic feature is, above all, an increase in the total mineralization of the water in the transition from raised bogs to floodplain lowlands, owing to an increase in the contents of calcium, magnesium, and the bicarbonate ion. In the same direction the pH of the waters also increases; oxidizability, the contents of free CO₂ and the NH₄ ion show the opposite tendency—an increase with the transition from lowland bogs to raised bogs; no substantial changes are observed in the content of the chloride ion and the sum of sodium and potassium ions. A low content of the sulfate ion (less than 4 mg/l) is characteristic.

The quantity of most microcomponents in the peats, with the exception of manganese, both total and plant-assimilable, is on the whole small.

The data presented in this communication should be regarded only as one of the first attempts to obtain information on the microcomponents of the waters and peats of the bog massifs of the West Siberian Lowland. Research in this direction must certainly be continued, since without taking microcomponents into account it is impossible to evaluate peat qualitatively as a fertilizer.

LITERATURE

1. A. Ya. Bronzov. Raised bogs of the Narym region (basin of the Vasyugan River). 1930.
2. T. V. Drozdova, S. M. Manskaya. Geochemistry of Organic Matter. 1964.
3. Ya. V. Peive. Methodological instructions for determining microelements in soils and plants. 1959.