by Acad. Vladimir BOLSHAKOV, and Tamara CHIBRIK, Cand. Sc. (Biol.), A. M. Gorky Ural State University

Industry-ravaged soils are turning into barren wastelands, virtual "moonscapes". In the Ural their areas top 100,000 hectares (250,000 acres), all that in a direct proximity to cities and other population centers. A hard case for residents...

This dire situation is neutralized by biological recultivation.

The technology has been developed and tested on the ash dumps of thermal electric power stations and on the ash disposal areas of coal and ore mines.

Many industrial enterprises in the Ural have begotten "company towns", i. e. communities depending on a particular company (plant) for jobs and livelihood. Built on urban outskirts, such enterprises expand and carve out chunks of urban territories proper. Next come pollution and other hazards. This is especially true of thermal power plants operating on high-ash coals and producing ash or ash-and-slag dumps (disposal areas), each hundreds of acres large. This situation holds at many fuel-burning power plants in the Sverdlovsk administrative region, e. g. at Krasnoturinsk, Verkhny Tagil, Kamensk-Uralsky and other electric stations. They act on the environment in a variety of ways, with "dust storms" being the worst case. The wind carries air-dried ash over ambient territories and pollutes them with particulates of ash and heavy metals.

Work on the biological recultivation of power plant ash dumps began in the 1960s by a team of Dr. Vitaly Tarchevsky, of Ural State University. They started by experimental seeding of perennial grasses, and tree- and bush-planting with the aim of selecting an adequate mix of plant species for the conservation of badly fouled ground and obtaining a permanent plant cover and sod. They attached much attention to upgrading the substrate (topsoil) at minimal costs. The first results of this exploratory work were realized in practice.

Thereupon, in the course of painstaking checks and verifications, soil science experts suggested techniques for ameliorating the characteristics of the substrates used. Today three basic techniques have been developed depending on a particular kind of ash dumps and location.

One is landfilling, that is putting the substrate (soil, peat or potentially fertile ground) on the surface of "industrial desertlands"; the overlayer can vary from 2 - 4 cm (5 - 10 inches) - for ash damps - and 20 to 50 cm (50 to 100 inches) and more - for overburden. An ash dump can be overlaid either evenly all through or in strips (strip sodding), each 6 to 10 m wide, arranged opposite the wind rose. Such strips are sown with perennial grasses or planted with trees and bushes in a parsimonious technique protecting a recultivated land plot.

The second technique is to apply a hollow mineral fertilizer (NPK) every year followed by additional fertiliza-

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tion of plants - all that with due account of the nutrients contained in the substrate above the dump. This operation proceeds in two stages: in autumn phosphate and potassium fertilizer is applied (30 to 60 kg per hectare, or about half as much per acre), while in spring-nitrogen fertilizer (30 - 45 kg/ha, or half as much per acre); that stimulates plant growth and the sodding of recultivated land.

And the last, third technique is to water the surface of disposal areas with effluents. This is done throughout the growing season - from May to September - 200 to 500 cu.m/ha (or about half as much per acre) in keeping with growth phases. Such effluents should conform to safety standards as to the concentration of harmful substances.

High-productivity forage crops are used for building up grass cover and sod: these are grasses (brome grass, cock grass, fescue, cock's foot, awned wheat grass, wheat grass Agropyrum cristatum, and timothy, and legumes (bastard lucerne, esparcet, biennial white and yellow melilots, white and red clover, etc.). Simultaneously, trees and bushes are planted, either in strips or in "clumps", or patches, which is important for snow retention and protection against water and wind erosion. The best trees and bushes for this purpose are the balsam poplar, crub apple, drooping and white birches, common pine, goat and bay-leaf willows, yellow caragana, dogrose, Russian broom, wild raspberry, sea buckthorn, golden currant, sugar maple, narrow-leaved Russian olive and many other related plants set out in holes or trenches filled up with soil or potentially fertile ground.

Culturphytocenoses formed by perennial grasses build up solid sods already in the third year, and dense herbage is good for hay making (productivity of grass crops ranges from 400 to 1,300 kg per acre, and that of legumes - from 1,000 to 2,200 kg).

By and large the Ural is coping fine. Botanical Gardens (Ural Branch of the Russian Academy of Sciences) team under Dr. African Makhnev is now involved with biological recultivation of the ash disposal area of a heat power plant at Reftinsky, a small urban community in the Sverdlovsk administrative region.

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But what about the lands - thousands and thousands of acres large - fouled by ore-mining enterprises? By way of example we can name open coal pits at Karpinsk (Sverdlovsk region) and Korkino (Chelyabinsk region). The latter is one of the largest and deepest coal cuts on the territory of the former Soviet Union. Its area totals 800 hectares (2,000 acres). Circular in form, its stretches latitudionally. The cast is over 500 meters deep, with the slope of flanks between 10 to 25°, and work-benches from 10 to 25 m high. Loosened by explosions, the rock is scooped up by excavators. The overburden is dumped in disposal areas 3 km to the northwest. The pit is surrounded by refuse heaps and spoil banks, and rock breakage zones are often filled up with surface waters. The total area of the Korkino mine with dumps and spoil heaps occupies 6,700 ha (16,750 a). Needless to say, a desolate zone as large as that has a specifics of its own; this is particularly true of worked-out areas. Cases of water encroachment above 100 meters are but rare. Water-saturated and boggy spots occur here and there on the southwestern edge of the pit due to the atmospheric precipitation and meltwater retained in the water-confining stratum; ground water may get through, too. But total inundation is hardly possible because of the absence of adequate headsources and thanks to water-insulation precautions: only a water column hundreds of meters high is capable of providing such hydrostatic pressure. Consequently, dry conservation is the best method of recultivation in this particular case.

As shown by surveys, such conservation is absolutely urgent-in terms of safety first and foremost. The thing is that the pit's edges are built of loose rock subject to weathering. The slopes and berms (benches) of the pit are a target of vigorous wind and water erosion whereby nearly all of the silt is removed. The stripped fragments of hard rock can cause landslides threatening urban structures.

Many machines and mechanisms employed at Korkino - alongside natural oxidation, wind erosion products, toxic gases and vapor, radioactive and can - cerogenic substances, and dust - pollute the air. The worst agents are nitrogen oxides, carbon monoxide, hydrogen sulfide, sulfur dioxide and acroleins, radon, thoron and actinon, aldehydes and cancerogens. In

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1968 the total air pollution time made up 2,228 hours, especially in autumn and winter months (the concentration of carbon monoxide averaged 0.005 - 0.008 percent against the permissible level of 0.0016 percent). Vegetation is the only provider of oxygen here. It was killed over an area of more than 6 thousand hectares (15,000 acres), a factor deteriorating the condition of the atmosphere.

Our recultivation project allows to reclaim large territories for cultivated fields and forestlands. More than that, it envisages activities aimed at recovering the productivity of desolated lands and improving the ecological situation. As many as 13 species of perennial grasses and 20 species of trees and shrubs have been tested at Korkino. Techniques of biological recultivation in the dry conservation mode have been developed and applied in part there (mostly on the upper benches of the pit).

According to biological recultivation prospects, the Ural coal deposits are divided into three groups: I - useful; II - of little use (poor lands); III - useless. Five ecologically sustainable models have thus been worked out.

Model I applies to useful dumps or those of little use for biological recultivation. The procedure includes ground breaking-grading (leveling); phytoamelioration (land improvement) for a term of two or three years to stabilize the ground surface; next, second grading; perennial grass seeding for hay- pasture- and forest-lands. This goes along with the application of organic and mineral fertilizer.

Model II holds for dumps older than 5 to 10 years built of rocks useful or of little use for recultivation, where intensive second growth is on. Partial landscaping of the relief is needed in such cases. Land plots may be set aside for pine-planting - 2 to 3 thousand saplings per hectare (1 to 1.5 thousand per acre).

Model III is for dumps useless for biorecultivation because of their chemical characteristics - pyrite impurities, high salinity and other drawback. Land improvement is followed here by the sowing of perennial grasses. To begin with, such land patches are graded and left to lie for two or three years. Thereupon this land is overlaid with an insulating cover of crushed stone or heavy (rich) clay, and this in turn is overlaid with rocks of groups I and II - the top layer is 40 to 50 cm (100 to 125 inches) on broken stone, and 20 to 30 cm (50 to 75 inches) on clay. Next comes the biological stage of recultivation - perennials are sown for hay- or pasture-lands, or with an eye to sanitary and hygienic considerations.

Unlike the previous three models, model IV has been developed for dumps built of stony rocks not fit for biological recultivation. We begin with the ground - breaking stage and only then get to landfill grading - the top layer should be 40 to 50 cm (100 to 125 inches) thick. The final stage includes the seeding of perennials and the planting of trees and bushes in a mix conforming to landscape gardening and recreation standards.

And last, model V: it is meant for dumps containing rocks no good for recultivation due to their physical or chemical properties, though mixed with group II ground (of little use). In that case ground relief should be restructured all through - leveled out and made orderly. Thereafter planting holes are prepared for trees, and trenches - for bushes. Both are filled with group I and II ground mixtures; the saplings are selected in conformity with sanitary and hygienic health conditions.

Models I and II have been realized at Bogoslovsky and Veselovsky coal deposits over 2 thousand ha (5 thousand a) large. The other three models have been tested, though on a limited territorial scale.

Thus, the Ural has amassed a significant know-how potential for the sanitation of urban environments. The focus is on the biological recultivation of "man-made desertlands" of different types, including those created by ore-mining facilities (disposal dumps of iron and copper-mining enterprises, of coal pits), ore-dressing and metallurgy mills (slurry slumps of ferrous and non-ferrous metal concentration mills and foundries), and ash dumps of fuel-burning power plants working on high-ash coal.

We have studied many parameters and characteristics, including the level of environmental pollution, prospects for natural rehabilitation of topsoil and plant cover, and possible trends in biological recultivation. We have determined the concentration of heavy metals in the substrate-plant system. Overall, we have surveyed 35,000 ha (87,500 a) of burned-over lands. Some of them have been recultivated using the techniques developed by our experts from A. M. Gorky Ural State University.