How toxic soil in the Arctic is brought back to life

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

The processing of copper-nickel ores in the Kola Peninsula is causing severe damage to the fragile Arctic ecosystems. Around the factories, which have been producing nickel, cobalt and other non-ferrous metals for 80 years, a zone of technogenic pollution has formed, reminiscent of a lunar landscape.

Can life be brought back here? The experiment of Russian soil scientists shows that this is possible. The research participants Vyacheslav Vasenev from RUDN University and Marina Slukovskaya from the Kola Scientific Center of the Russian Academy of Sciences spoke about their work N + 1.

N + 1: What is the essence of the damage caused to the forest-tundra by the production of valuable metals?

Vyacheslav Vasenev:The soil in the wasteland around the plant is highly degraded, toxic and practically unsuitable for plants: it contains a lot of copper, nickel and other heavy metals.

These metals entered the soil through the air. The plant emits various compounds into the air, and micron-sized dust particles, aerosol droplets settled around the plant for decades. Metal compounds gradually precipitated in the forests around the plant, which ultimately led to the death of trees and other vegetation, and so much metals accumulated in the soil that they can be re-mined if desired. The main problem is that a large proportion of metals are found in the soil in the form of soluble compounds that are easily absorbed by living organisms.

How far is the wasteland around the mill?

Marina Slukovskaya:The zone of influence of the plant reaches about 200 square kilometers, and the wasteland itself is about a third of the total area.

BB:When approaching the plant, the suppression of ecosystems can be monitored by the state of vegetation. The wasteland itself starts just a few kilometers before the factory, but the depressive landscape is found earlier. In the northern taiga, the vegetation is not very dense anyway, and a few kilometers from the plant it becomes noticeable how everything around begins to wither, thin out, turn yellow and die.

How does your artificial soil system work and how does it work?

MS:We made a so-called soil structure - technozem. The lower layer consists of mining waste containing calcium and magnesium carbonates and silicates, and the upper layer is made of vermiculite, a hygroscopic layered mineral from the hydromica group, which is especially important at the stage of seed germination and the beginning of plant growth.

BB:Waste from the mining industry contains little heavy metals, so this pillow well shields the underlying layers. In addition, it immobilizes metals, in fact, prevents them from leaking and flying away.

As a result, the layer of alkaline waste allows you to neutralize the acidic environment and sets the minimum agrochemical properties, while the upper one retains water and allows seeds to germinate and gain a foothold in the waste layer.

The restoration of the natural Arctic soil under these conditions would take a couple of hundred years, and only after the termination of the activities of the plant, which is not going to be closed. Reclamation using technozems can speed up the process and protect the soil from erosion.

How expensive is this method?

MS: The reclamation of one hectare (0.01 square kilometer) requires about 3.5 million rubles. This is comparable to the cost of imported fertile soil, but for this you need to dig it up and take it out somewhere, that is, disrupt other ecosystems, and we use waste.

By next year, we plan to conduct another study in order to calculate the value of the lost ecosystems, that is, we will estimate the accumulated damage and compare it with the cost of reclamation. Indeed, in this case, we are not talking so much about the cost of materials and technology. It is about the quality of soil, water, air and other components of the ecosystem.

In the case of reclamation, it often happens like this: you consider the cost of work and materials, it seems that there is a lot, but if you look at all the accompanying advantages, it turns out to be inexpensive.

In addition to creating new soil, you are also planting plants. What exactly are you planting and why?

MS: We plant mainly cereals. We experimented with legumes too, but unfortunately they died. The cereals came up much better, especially since we initially selected species that have a chance of survival. Due to their rapid growth, they are well fixed in the soil, and the leaves do not accumulate pollution too much. Bonfire, wheatgrass and volosnets showed themselves best of all - summer residents would have fought with them, and we are glad that they are growing. Probably, if you plant a hogweed, then it will also feel good, but we, perhaps, will not do this for now.

BB: It is important that not only tall green grass grows in the reclamation sites, but also the functions of the soil are restored, organic carbon accumulates, and the microbial community develops. So far, some of the nutrients, for example nitrogen, are applied in the form of fertilizers, but over time we can expect more and more autonomy of the system.

The plots also attract animals: hares come to feed on the grass, and this year, mice have settled on an area with very dirty peat soil less than a kilometer from the plant and dug holes for themselves in experimental technozems. It's amazing that, in fact, the experimental sites are green islands surrounded by rocky landscape, but as you can see, life appears wherever it is given a chance.

MS: The migration of animals somewhat interferes with scientific research, because, as a result, we do not know the correct figures for the biomass of plants and cannot be completely sure of the data on the accumulation and migration of metals in technozems. But in these works, the main goal is not only new articles or grants, but also a very clear, visible benefit for living beings. After all, the main idea is not just to fill in materials and plant grass. We investigated how it is possible to restart ecosystem processes in the extreme conditions of the Kola Peninsula, where it is very cold and high degree of pollution.

The first experiment on the use of mining waste in the wasteland was laid in 2010. For almost ten years of work, we have experimented on the two most common soil types in the region, podzol and peat soil, where we worked with a total of ten types of mining waste, both in the initial state and with their enriched and thermoactivated versions.

The plant has been operating since the 1930s and continues to emit toxic dust ever since. Will you have to redo all the plantings again in a few years?

MS: Yes, production began back in 1938 and has not stopped to this day. But it passed its most unfriendly phase, the peak was from about 1978 to 2000. Now they are trying to control emissions, filters are installed, production is being reconstructed, and the plant emits about 50 thousand tons of dust per year, which is three times less than in the 1990s.

Unfortunately, already accumulated pollution causes no less harm. Although new pollution is constantly coming in, so far there is no need to remodel the sites: the “cushion” of waste manages to immobilize the incoming metals.

It is difficult to predict for decades ahead, but so far the state of vegetation depends more on weather conditions than on anything else. For example, the last summer of 2019 was very cold, and despite the fact that the cereals threw out the ears, the seeds did not have time to ripen by the end of August.

In general, we see that organic matter is accumulating, the microbial community is developing, a new organic horizon has appeared above the mineral layer of waste. At the same time, we have control plots, where instead of waste we took ordinary sand - and so, both plants and microbes feel much worse on it than on waste, that is, the correct choice of material is really decisive for the fate of planting.

Why is it necessary to do reclamation at all? Can't you just abandon the disturbed area and wait for the ecosystem to heal itself?

BB: The most important thing in reclamation is not even the fact that ecosystems are being restored in heavily disturbed areas. This also makes it possible to improve the ecological situation in the region as a whole. Heavy metals are immobilized and can no longer get into ground and surface waters, and from them into rivers and into Lake Imandra, a reservoir of the highest fishery category.

Are there examples of large-scale reclamation projects in Russia or in the world?

BB: And in the Murmansk region, and in Russia as a whole, I do not yet know of examples when such a technology would be used on a large territory. In the rest of the world, there are such examples, but basically such work was carried out after the closure of the enterprise, that is, just after the transfer of the territory completely into the zone of state responsibility. For example, in Canada, a large-scale reclamation work was carried out with the involvement of students and the unemployed in the area around the copper-nickel plant.

I was at a facility in Mexico where a refinery site was reclaimed. In the ponds, pollution penetrated tens of meters deep, where not only oil products, but also a huge amount of heavy metals were accumulated, since lead white was used in production for a long time. Now a large park has been set up on the site of the plant.

You take both vermiculite and soil for the pillow from the nearby factories. What about those who are engaged in reclamation, for example, in the Urals and do not have access to these materials?

MS: Instead of vermiculite, you can use gel, synthetic polymers and any other moisture-consuming materials - everything that will protect plants from drying out in the early stages of development. With regard to waste, in many places where there are ore processing facilities there are also facilities for their extraction, which means, most likely, you can find suitable waste. Of course, this rule does not always work, and not all waste can be effective, but this is what specialists are needed to understand these issues.

What other types of contaminated areas can be reclaimed using your method? For example, can it be applied to oil spills?

BB: The very approach of creating soil structures is often used for reclamation of various disturbed lands. Alkaline materials are most commonly used to contain and eliminate heavy metal contamination. The technology scheme is determined not only by the type of pollution, but also, for example, by factors such as soil type, climate and much more. Each disturbed territory is a complex system, therefore, in such as ours, there is no and cannot be a universal solution to the problem.

MS: The constructions we work with are a unique long-term experiment. For almost a decade we have been observing the development of ecosystems and soils in truly extreme conditions, combining constant pollution and the harsh polar climate. There are only a few such works all over the world, and perhaps that is why it is so interesting for us.