Ecological rehabilitation through reforestation of tailings dumps results from
the ore flotation processes, so-called “tailings ponds.” Tailings, although more
restricted in size, are a real danger to the surrounding population and the natural
environment through strong air pollution, groundwater, or flowing water as a result
of the toxic substance content.
The major danger of pollution, primarily air, is due to the presence in the tailings
of substances, such as cyanide, Pb, Zn, Cu, S, etc. Following the very fine particle
size of the tailings deposit, these substances are trained even by the weakest air
currents. Arguments in support of this statement are the data of the measurements
taken within 6 months, a 27.4-cm-thick tailings layer, or the sterile accretions in live
fruit plantations; the crops around the heaps measure up to 30 cm thickness annually.
This explains, in the latter case, the formation over time of sterile dunes with heights
of up to 5 m. At the same time, the mentioned toxic substances participate in the
chemical solution in the “soil,” together with other results of the processes of
flotation, limiting factors of the installation of forest vegetation (and not only of it)
on these ponds.
Under such conditions, it is inconceivable to develop even herbaceous vegetation
without extremely costly measures to combat deflation and to improve soil
conditions. Thus, in the case of Pb and Zn, although the forest cultures accounted
for only 3.7% of the recultivated areas, the remainder is being covered with perennial
grasses, glue plaques, borrowed land coverings, garbage disposal, manure, sludge
from sewage treatment plants, and an amendment to limestone rock. In the case of
tailings ponds, it should be mentioned that the value of the investment represented
900,000 euro/ha (value in 2017), one of which was only 29% of the plantations
(including the price of dung) and maintenance of the forestry crops, the rest
representing stabilization and soil improvement works. It should also be noted that
the use of gullies or land lending leads to the degradation of the land where they were
procured.
With all these laborious and costly works, the improvement of the vegetation
conditions for the forest cultures is achieved only to a small extent. Thus, the
14-year-old cultures achieved average annual growths from 23.7 cm at P. sylvestris
to 45.5 cm at the tremulous.
Euroamerican poplars at the bottom of the slopes record average annual
elevations of only 45 cm, which can be an indication of the pollutant effect of
pond infiltrated waters on surrounding soils. It is worth noting the very poor
development in these conditions of the black alder, which only achieves 13 cm
growth. Acacia and birch are intermediate. Of the shrub species, the best growth is
recorded by the shallow willow (43.3 cm), the mean height, being of 20 cm.
Some fruit trees, such as plum and sour cherry, but with all the special planting
and care measures, have been tried in these conditions; most of the specimens have
disappeared, and the remaining ones have a lingering growth with an annual average
of only 12 and 5 cm, respectively. Already after the 4th year since planting, the state
of the seedlings is laced, even in some species, such as the shrub, which had a good
development in the early years. Under these conditions, with the exception of the
Alnus glutinosa, which achieves an average annual growth of 42.1 cm, the other tree
120
M. Butu et al.
the ore flotation processes, so-called “tailings ponds.” Tailings, although more
restricted in size, are a real danger to the surrounding population and the natural
environment through strong air pollution, groundwater, or flowing water as a result
of the toxic substance content.
The major danger of pollution, primarily air, is due to the presence in the tailings
of substances, such as cyanide, Pb, Zn, Cu, S, etc. Following the very fine particle
size of the tailings deposit, these substances are trained even by the weakest air
currents. Arguments in support of this statement are the data of the measurements
taken within 6 months, a 27.4-cm-thick tailings layer, or the sterile accretions in live
fruit plantations; the crops around the heaps measure up to 30 cm thickness annually.
This explains, in the latter case, the formation over time of sterile dunes with heights
of up to 5 m. At the same time, the mentioned toxic substances participate in the
chemical solution in the “soil,” together with other results of the processes of
flotation, limiting factors of the installation of forest vegetation (and not only of it)
on these ponds.
Under such conditions, it is inconceivable to develop even herbaceous vegetation
without extremely costly measures to combat deflation and to improve soil
conditions. Thus, in the case of Pb and Zn, although the forest cultures accounted
for only 3.7% of the recultivated areas, the remainder is being covered with perennial
grasses, glue plaques, borrowed land coverings, garbage disposal, manure, sludge
from sewage treatment plants, and an amendment to limestone rock. In the case of
tailings ponds, it should be mentioned that the value of the investment represented
900,000 euro/ha (value in 2017), one of which was only 29% of the plantations
(including the price of dung) and maintenance of the forestry crops, the rest
representing stabilization and soil improvement works. It should also be noted that
the use of gullies or land lending leads to the degradation of the land where they were
procured.
With all these laborious and costly works, the improvement of the vegetation
conditions for the forest cultures is achieved only to a small extent. Thus, the
14-year-old cultures achieved average annual growths from 23.7 cm at P. sylvestris
to 45.5 cm at the tremulous.
Euroamerican poplars at the bottom of the slopes record average annual
elevations of only 45 cm, which can be an indication of the pollutant effect of
pond infiltrated waters on surrounding soils. It is worth noting the very poor
development in these conditions of the black alder, which only achieves 13 cm
growth. Acacia and birch are intermediate. Of the shrub species, the best growth is
recorded by the shallow willow (43.3 cm), the mean height, being of 20 cm.
Some fruit trees, such as plum and sour cherry, but with all the special planting
and care measures, have been tried in these conditions; most of the specimens have
disappeared, and the remaining ones have a lingering growth with an annual average
of only 12 and 5 cm, respectively. Already after the 4th year since planting, the state
of the seedlings is laced, even in some species, such as the shrub, which had a good
development in the early years. Under these conditions, with the exception of the
Alnus glutinosa, which achieves an average annual growth of 42.1 cm, the other tree
120
M. Butu et al.