Study of Chemical Pollutants and Ecological Reconstruction Methods in the Tismana I Quarry, Rovinari Basin, Romania

Abstract

The phytoremediation of polluted land in Romania is based on research on biodiversity, environmental protection, and the sustainable use of natural or man-made resources, carried out by universities and research institutes for over 30 years, synchronized with those at the European and global level. The aim of this paper is to establish the categories of pollutants with potential environmental, economic, and social impacts associated with mining in order to choose the optimal method of ecological reconstruction. In this regard, the Tismana quarry was mapped, the surface of the analysis plot was set at 50 m × 50 m, and the sampling depth was 0–20 cm; from each plot, two samples were collected. Out of a total of 121 analysis plots, ten susceptible plots were identified, from which 20 samples were collected and analyzed. The samples were analyzed by the UV-VIS spectrophotometer method—MLUV1720 and UV spectrometry—with a SHIMADZU UV 160U spectrophotometer; they indicated in only three analysis plots a pollution with phenols, Ni, Zn, Ni and HAP, the concentrations of which exceeded only the normal values, which does not affect the eaves threshold and intervention for the type of land use. Being point pollution, the phytoremediation of these soils can be achieved in a short time. The paper aims to present the situation of chemical pollutants in the Tismana quarry area, and to offer different ecological rehabilitation solutions depending on their presence.

1. Introduction

Coal is a key component of national energy security. Romania has total reserves of 12.6 billion tons of lignite, with an average calorific value of 1800 kcal/kg, geographically concentrated in the Oltenia Mining Basin. The deposits in operation total 986 million tons. The annual lignite production decreased from 31.6 million tons in 2012 to 22.1 million tons in 2015; in 2017, the share of primary energy resources in the production of electricity produced from coal (lignite and coal) was 27.5% (17.3 TWh). The energy produced from coal will continue to decrease to 15.8 TWh, and will have a share of 20.6% [1]. The mining activity produces, due to its specificity, multiple and varied negative effects on the environment, exemplified by changes in the relief, manifested by the degradation of the landscape and relocations of households and industrial objectives in the exploitation areas; the occupation of large areas of land for the activity of exploitation, land filling, the storage of useful mineral substances, industrial installations, and access roads, etc., areas which thereby become completely unusable for other purposes, for a long time, with effects on local communities (land use conflicts, relocations, and the destruction of recreational areas, etc.); land degradation, by the vertical and horizontal movements of the surface and landslides of dumps and tailings ponds, causing serious accidents; the pollution of surface runoff and groundwater; the hydrodynamic imbalance of groundwater [2]; negative influences on the atmosphere, flora and fauna of the area; the chemical pollution of the soil, which can affect its fertile properties for many years [3]; and noise, vibration and radiation spread in the environment, with a strong unfavorable action [1].

Today, we are witnessing the expansion of ecological risks, caused by some real and special situations in which many of the mining units operate, namely the ever-increasing volumes of waste rock extracted, transported and stored, due to increasing amount of mineral raw materials needed by society and the real situation we are in, to exploit and capitalize on deposits with ever-smaller useful components (which means exploiting and preparing larger quantities of ores to obtain the same quantities of finished products) [2]. There is also the extension of the mining activity in areas that have particular characteristics (karsts areas, areas with complex aquifer formations, areas with a labile stability, etc.), from which derive long-term negative influences and with extension over long distances, and the mining activity must be carried out in a place strictly related to the existence of the deposit; this fact can create special ecological problems, in a sensitive area for the conservation of the ecosystem [4].

People and governments have always placed importance on and given attention to the damage and negative influences of mining activities with regard to environmental factors (water, soil, and air). In this sense, numerous pieces of research have provided better and better methods of depollution [5,6,7], to maintain the physico-chemical parameters (of the water, soil, and air) within the allowed limits. Furthermore, as a result, legal regulations have emerged, which aim to protect environmental factors and, implicitly, mineral resources (the national/international framework of norms, standards and laws in the field must be respected) [8].

Very difficult environmental conditions have been imposed in the field of the environment for the entrepreneurs who set out to exploit and capitalize on the deposits of useful mineral substances through their underground or surface exploitation. Over time, there has been close competition between administrative, economic, social and strategic interests related to the exploitation of deposits of useful mineral substances and public—and even private—interest, which refers to the optimal use of environmental resources (landscape, territory, surface and groundwater system, atmosphere, etc.), which are undoubtedly attacked and disturbed by mining activity [9]. Consequently, it is clear that mine and quarry designers, those who lead or will conduct productive activities on the ground, and the central and local public authorities responsible for the protection of natural assets will need to anticipate adverse effects and adapt measures to prevent, protect and restore the environment [9].

The main factors that have contributed to the degradation of soil, water and air in the perimeter of the quarries are anthropogenic in nature, and consist of excavation, transport and landfill operations of tailings and coal, chemical pollution with petroleum products (diesel, lubricants, etc.), and other factors that lead to an instability of the areas affected by erosion phenomena and landslides, etc., of which the influence is closely linked [10,11].

Through the activities carried out for the exploitation of lignite in the quarries in the areas bordering the Rovinari perimeter, to a greater or lesser degree, all environmental factors are polluted by emissions of pollutants into air and water, by the total degradation of land located in the excavation perimeters, and also by natural factors. Morphologically, the mining perimeter is generally characterized by a hilly area with low relief energy; the average slope of the slopes is 10°–12° to the base and 35°–40° in some places in the upper part, with the average height of the slopes generally being between 270 and 300 m, being furrowed by a series of valleys and meanders oriented in the west–east direction. The area is affected by numerous local instability phenomena; some are active and others are temporarily stable, but could still be reactivated in the conditions of the non-correlation of the quarry exploitation works with the deforestation works of the forest areas.

Coal mining, within the Tismana I quarry, visibly affects the environmental factors (soil, subsoil, water, air, flora and fauna, noise and vibration, human settlements). The soil is the main factor that suffers significant damage because of the coal mining activity in the perimeter of the Tismana I quarry, now and in the future. The impact produced is of a quantitative and qualitative nature [1].

From a quantitative point of view, the impact on the soil is caused by the occupation of the quarry soils, the outer and inner dump, and utilities that serve the quarry, with their temporary or permanent removal from the productive, agricultural or forestry circuit. Currently, the quarry operates on an area of 708.92 ha. In order to continue the exploitation of coal in the quarry, until the works are closed, it is necessary to occupy a final area of 331.50 ha (of which 129.08 ha is agricultural and 202.42 ha is forestry) (Figure 1, first author’s personal archive).

From a qualitative point of view, the impact on the soil is manifested by the destruction of the fertile layer, which is rich in organic matter, and changes in the natural lithological structure up to depths of 140 m. The formation of tailings dumps led to the creation of a new local morphology, with an anthropogenic soil profile which is totally different from the original soil. The formation of a new soil involves a great diversity of works that take place over a long period of time.

From the point of view of the impact on the subsoil of the area, it is also felt to affect the groundwater and groundwater level, with this being more a form of quantitative impact and less of a physical nature. In the 30 years of activity, some of the soils occupied by this mining objective have been released from technological tasks and arranged by the care of the mining unit [1].

The following areas were arranged: the pine plantation on the Tismana perimeter, 32 ha located on the outer dump, and 8 ha on the slopes of the guard canal on the northern side of the quarry. The components of the air and subsoil environment are qualitatively affected, and the environmental factors of the water, soil, flora and fauna, noise and vibration, and human settlements are affected from both quantitative and qualitative points of view. The rough impact of the soil is characterized by the occupation of quarry soil surfaces, outdoor dumps, warehouses, and constructions (Figure 2, first author’s personal archive).

The qualitative impact is manifested by affecting the fertility of the soil through physical pollution, with tailings dust, coal, local erosions, and morphological changes with the change of the surface water drainage regime. Due to the large areas of disused agricultural and forestry land and the relocation of villages, the impact on the soil is negative in terms of initial use, and moderately negative in terms of erosion and natural waste [1].

The main types of soils in the Tismana I quarry region are pseudoglycic soils, brown luvic soils, altruistic luvic soils, and typical rogosols, erodisols, and protosols. These soils can be found in complexes and soil associations, with their reaction being weak-to-moderately acidic to strongly acidic (pH = 5.2–5.6). The humus content is medium, and the texture is medium on the surface and heavy in depth. The degree of saturation indicates a moderately saturated soil. The bedrock is composed of fluvial river deposits. The fertility of these soils is average. During coal mining, the soil pollution was accidental and of small proportions, and consisted of possible leaks of fuels and lubricants from the work equipment that served the quarry (excavators, bulldozers, dump trucks) and pollution with iron hydroxides from the metal structures of various machines and devices [12,13,14].

The activity of exploiting the lignite deposit from the mining perimeter of the Tismana I quarry led to the degradation of the soil and the subsoil and is characterized by the deforestation of vegetation, fertile soil being discovered. For many reasons (i.e., sterile coal excavations, the action of scrapers, the transport of coal and tailings with conveyor belts, the existance of tailing deposits in the inner dump, the deposition of coal in the central depot (mains sector), mechanical and electrical interventions, the occupation of areas with quarry activities characteristic of the outdoor dump, the technological road, etc.) soil degradation and decreased fertility class have been observed (correlated with the disappearance of morphogenetic horizons with productive qualities, the destruction of the natural geological environment up to a depth of 15 m, as well as changes in soil physico-chemical balance) [1].

Landslides have occurred on the slopes of the quarry. Deposits at the upper stages of the tailings were made through voids. In these gaps, infiltrating water has accumulated and is accumulating, which can generate movements of mining masses. The geometric elements of the quarry soils and the inner and outer dumps returned to the economic circuit were established considering the assurance of the stability conditions of the soil and of the edges, for avoiding human and technical accidents.

Considering the current situation, the hearth of the Tismana I quarry and its slopes, the following main categories of works are proposed to be performed in order to restore the ecological balance, as follows:

■

geotechnical drilling to monitor surface stability;

■

the reprofiling of high slopes with classic excavators.

The reprofiling consists of steps with a maximum height of 7.0 m, designed to be executed below the contour line. The final guarantees between the extracted steps have average widths of 5–7 m. Soils released by technological loads are returned to the productive circuit. Fertile soil deposits are properly maintained. There is a physical pollution of the subsoil and the soil in the mining perimeter from the mining and extraction works, caused by drying and damaging the underground water route.

The aim of this paper is to establish the categories of pollutants with potential environmental, economic, and social impacts associated with mining to choose the optimal method of ecological reconstruction. The novelty of the study consists in the identification of the types of pollutants from the collection points and the punctual and differentiated use of phytoremediation techniques simultaneously with the ecological reconstruction works in the areas without chemical pollutants. We chose this topic in order to restore, in a short time, the quality of the chemically polluted soil with low costs, and to restore biodiversity on these degraded lands. This approach is unique compared to other works dealing with integrated phytoremediation, which require more time to restore ecosystems in polluted vs. unpolluted areas.

2. Materials and Methods

2.1. Soil Sampling Points

In order to evaluate the quality of the soil affected by the mining activity in the Rovinari mining basin (44°53′53″ N and 23°09′11″) and the Tismana I quarry (44°55′07″ N and 23°06′59″ E) in 2021, soil samples were collected from the mining perimeter, from the most heavily polluted areas visibly, physically, and chemically.

The location of the sampling points considered the activity carried out on the site and the possibility of accidental pollution (

Table 1. Sampling points.

No.	Soil Sampling Point Symbol	Name of Soil Sampling Point
1	S1A, S1S– soil	Materials warehouse recovered Rovinari
2	S2A, S2S– soil	Poiana colony
3	S3A, S3S– soil	Warehouse subassemblies recovered Gârla
4	S4A, S4S– soil	The northeastern part of the quarry
5	S5A, S5S– soil	Hodăreasca village, the first house
6	S6A,S6S– soil	Găleşoaia village, the first house
7	S7A,S7S– soil	Near the first house in Pinoasa village, in front of the Tismana I mining perimeter
8	S8A, S8S– soil	Exit from career
9	S9A, S9S– soil	In the Tismana I quarry waste oil depot, 30 m from fixed oil storage containers
10	S10A, S10S– soil	Near the first house in the village of Arderea, near the perimeter of Tismana I

). For the sampling of the soil, the sampling points were marked on the situation plan of the area (Figure 3, first author’s personal archive). Vegetation was completely removed from the sampling surface, and samples were collected from two different elevations at the same point, from the soil surface (S_S) and from a depth of 20 cm from the soil surface (S_D). The number of the sample, the depth of sampling, and the place of sampling were noted on the plastic bag in which the samples were taken.

When choosing the sampling points, the works carried out in the mining perimeter, the direction of the groundwater flow and the nearby inhabited areas were considered. The sampling points were in the excavation area, the area of the depositing of the sterile material in the dump, at the place where the front strips were unloaded, on the connecting strips, at the distribution nodes, at the deposition of coal in the warehouse and its dispatch, near the roads of access, in the storage area of fuels and lubricants (diesel, oils), and near homes.

The Tismana quarry was mapped, the surface of the analysis plot was set at 50 m × 50 m, and the sampling depth was 0–20 cm; from each plot, 2 samples were collected. Out of a total of 121 analysis plots, ten susceptible plots were identified, from which 20 samples were collected and analyzed. The samples were analyzed by the UV-VIS spectrophotometric method—MLUV1720 and UV spectrometry—with a SHIMADZU UV 160U spectrophotometer (the apparatus characteristics are provided in

Table 2. Apparatus, reagents, and methods used for the analysis of the soil samples.

Apparatus	Reagents	Method
Sulphates of Cd, Cu, Pb, Ni, Zn, and Phenols Determination by Turbidimetry Method
Atomic absorption spectrophotometer Agilent 280FS (Agilent Technologies, Inc., Santa Clara, CA, USA) Agilent Sample Introduction and Preparation System, Double Pump Accessory (SIPS 20) (Agilent Technologies, Inc., Santa Clara, CA, USA) Achieve high sensitivity—typically > 0.9 Abs. from 5 mg/L Cu.	240 g NaCl + 20 mL HCl + H2O up to 1 L 50 mL glycerol + 100 mL EtOH and BaCl2 0.1479 g Na2SO4 + H2O up to 1 L Reagents from Merck KGaA, Germany.	5 g of air-dried soil + 50 mL of distilled H2O; the resulted suspension was filtered through Whatman filter paper, the filtrate being analyzed.
Cyanides Determination by Spectrofluorimetric Method
UV-VIS Fluorescence Spectrophotometer (FLS1000 Spectrofluorometer, Edinburgh Instruments Ltd., Livingston, UK). Sensitivity >35,000:1 standard H2O Raman measurement conditions: excitation λ = 350 nm excitation/emission bandwidths =5 nm step size = 1 nm integration time = 1 s emission λ = 397 nm noise measured at 450 nm calculation based on the SQRT method	At an aliquot of 1 mL standard cyanide solutions + 10 mL H2O + 8 mL PBS + 2 mL CAT reagent. Leave the solution to stand for 5 min. +10 mL solution of PY and H-Bar + H2O up to 50 mL. The solution is leaved to stand for 1 h. Reagents from Merck KGaA, Germany.	Determination of easily released cyanide by steam distillation of buffered and air-dried soil, pH = 4, followed by spectrophotometric determination using CAT and H-Bar. The absorbance of the solution is read in a cell with a path length of 10 mm, λ = 575 nm, using H2O as control solution. This λ may not be the maximum absorption λ. The absorbance calibration based on the amount of cyanide in V1 mL of standard working cyanide solution is plotted.
Polynuclear aromatic hydrocarbons (PAHs) determination by HPLC chromatographic method
Agilent ZORBAX Eclipse PAH Column (4.6 mm × 50 mm, 1.8 mm), p/n 959941-918 (Agilent Technologies, Inc., Santa Clara, CA, USA) Agilent 1200 Series HPLC (Agilent Technologies, Inc., Santa Clara, CA, USA) equipped with a binary pump and a FLD set to variation with excitation and emission wavelengths. Data were processed by 2D HPLC. In the case of the method using the FLD detector, the sensitivity (signal-to-noise ratio> 10: 1) is in the range of picograms.	CH3CN and PAH were purchased from Sigma-Aldrich (St. Louis, MO, USA). H2O used came from a MilliQ system (Milford, MA, USA). The mobile phase was filtered through a Whatman membrane filter (47 mm diameter, 2 μm pore size). Standard stock solutions (1 mg/mL) were prepared by dissolving 10 mg of PAH in 10 mL CH3CN, stored at −20 °C. The daily working solutions were freshly prepared by serial dilutions with CH3CN.	Analytes were separated on the column by gradient elution with a binary system of CH3CN-H2O with subsequent fluorescence detection set at the corresponding excitation/emission λ. The recoveries of the analytes varied between 86.0–99.2%, with RSD ranging between 0.6–1.9%, at 3 different levels of fortification. LODs ranged from 0.005 to 0.78 ng/g, and the LOQs ranged from 0.02 to 1.6.6 ng/g. The selection of excitation/emission λ for fluorescence detection was based on the optimal responses for different PAHs.

Cu, copper; nm, nanometers; mm, millimeters; μm, micrometers; mL, milliliters; mg, milligrams; ng, nanograms; g, grams; V, volume; λ, wavelength; CH₃CN, acetonitrile; H₂O, water; CAT, chloramine-T; EtOH, ethanol; H-Bar, barbituric acid; PBS, phosphate buffer solution; HPLC, high-performance liquid chromatography; RSD, relative standard deviation; SQRT, square root; PAH, polynuclear aromatic hydrocarbons; PY, pyridine; FLD, fluorescence detector; LOD, limit of detection; UV-VIS, ultraviolet visible spectroscopy; FLS, photoluminescence spectrometer; UK, the United Kingdom; USA, the United States of America.

), indicating in only three analysis plots a pollution with phenols, Ni, Zn, Ni and PAH; their concentrations exceeded only the normal values, and do not affect the eaves threshold and intervention for the type of land use. Being point pollution, the phytoremediation of these soils can be achieved in a short time.

The Rovinari mining area covers tens of km², and there is no area which is unaffected by mining works, such that the standard test cannot be discussed. The soil samples collected were sent for chemical analysis to ECOIND Bucharest, Romania. Soil pollution in mining perimeters is a physical pollution due to the excavation of soil and rock masses. Chemical pollution occurs only in warehouses (in addition to the used oil containers for their handling, and in areas of premises where there is vehicular traffic and maintenance work). Soil samples collected from the Tismana I quarry were chemically analyzed by specific methods, and the main chemical quality indicators were determined: heavy metals (copper, cadmium, lead, zinc, and nickel), sulphates, free cyanides, PAH (naphthalene, phenanthrene), anthracene, fluoranthene, pyrene, benzo-anthracene, chrysene, benzo-fluoranthene, benzopyrene, benzoperilene, and indenol ((123) pyrene).

2.2. Apparatus, Reagents, and Methods

The soil samples were analyzed by various methods, depending on the analyzed compounds, as detailed in Table 2.

3. Results

The results obtained from the analyses for each soil sample collected from the two levels are shown in

Table 3. Concentrations of the quality indicators of soil samples collected from points S₁–S₅.

Quality Indicators (mg/kg su) (LOD/LOQ)	Soil Sampling Points
	S1S	S1A	S2S	S2A	S3S	S3A	S4S	S4A	S5S	S5A
Level	I	II	I	II	I	II	I	II	I	II
Cadmium (2.0/6.6)	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *
Lead (2.0/6.6)	2.57 ± 0.01	2.52 ± 0.07	<2.0 *	<2.0 *	2.62	2.66 ± 0.03	<2.0 *	<2.0 *	<2.0 *	<2.0 *
Free cyanides (0.05/0.16)	<0.05 *	<0.05 *	0.21 ± 0.05	<0.05 *	<0.05 *	0.083 ± 0.03	<0.05 *	<0.05 *	<0.05 *	<0.05 *
Phenols (2.0/6.6)	0.23 ± 0.03	<2.0 *	0.08 ± 0.01	0.23 ± 0.01	<2.0 *	0.25 ± 0.01	0.15 ± 0.01	0.17 ± 0.01	0.39 ± 0.03	0.66 ± 0.02
Sulphates (0.1/0.33)	339.1 ± 0.10	141.12 ± 0.21	248.11 ± 0.13	98.03 ± 0.11	198.93 ± 0.27	102.05 ± 0.31	98.22 ± 0.07	49.27 ± 0.05	97.65 ± 0.11	97.94 ± 0.23
Copper (2.0/6.6)	21.41 ± 0.07	8.4 ± 0.10	4.31 ± 0.21	3.32 ± 0.05	13.09 ± 0.10	8.85 ± 0.11	4.27 ± 0.02	8.55 ± 0.07	4.78 ± 0.09	4.79 ± 0.08
Nickel (2.0/6.6)	16.64 ± 0.03	<2.0 *	<2.0 *	<2.0 *	31.83 ± 0.13	17.2 ± 0.10	<2.0 *	16.62 ± 0.11	16.47 ± 0.11	16.52 ± 0.10
Zinc (0.1/0.33)	214.06 ± 0.12	255.0 ± 0.19	32.31 ± 0.22	12.25 ± 0.18	342.76 ± 0.29	79.1 ± 0.17	19.8 ± 0.10	53.45 ± 0.23	59.03 ± 0.18	59.17 ± 0.10
PAH (0.01/0.033)	2.9 ± 0.07	0.1 ± 0.03	0.14 ± 0.03	0.24 ± 0.02	0.03 ± 0.01	0.14 ± 0.02	0.27 ± 0.10	0.13 ± 0.03	0.09 ± 0.03	0.18 ± 0.02
Naphthalene (0.01/0.033)	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Phenanthrene (0.01/0.033)	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.03 ± 0.01	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Anthracene (0.01/0.033)	0.05 ± 0.01	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Fluoranthene(0.01/0.033)	0.07 ± 0.01	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Pyrene (0.01/0.033)	1.32 ± 0.03	<0.01 *	0.02 ± 0.01	0.02 ± 0.01	<0.01 *	0.06 ± 0.10	0.05 ± 0.10	0.05 ± 0.01	0.03 ± 0.01	<0.01 *
Benz(a) anthracene (0.01/0.033)	1.28 ± 0.03	<0.01 *	0.02	<0.01 *	<0.01 *	<0.01 *	0.04	0.03	<0.01 *	<0.01 *
Chrysene (0.01/0.033)	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Benz fluorantrain (0.01/0.033)	0.18 ± 0.01	0.1 ± 0.01	0.1 ± 0.01	0.22 ± 0.03	0.03 ± 0.01	0.05 ± 0.01	0.18 ± 0.10	0.05 ± 0.02	0.06 ± 0.03	0.18 ± 0.02
Benz(a) pyrene (0.01/0.033)	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Benzo(ghi) perilen (0.01/0.033)	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Indene pyren (0.01/0.033)	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *

* Detection limit of the method; SS, soil surface; SA, depth 20 cm; LOD, limit of detection; LOQ, limit of quantitation; PAH, polynuclear aromatic hydrocarbons.

(for the first five sampling points) and

Table 4. Concentrations of the quality indicators of soil samples collected from points S₆–S₁₀.

Quality Indicators (mg/kg su)	Soil Sampling Points
	S6S	S6A	S7S	S7A	S8S	S8A	S9S	S9A	S10S	S10A
Level	I	II	I	II	I	II	I	II	I	II
Cadmium	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *
Lead	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	36.9
Free cyanides	0.046 ± 0.03	0.057 ± 0.03	<0.05 *	<0.05 *	<0.05 *	0.18 ± 0.04	<0.05 *	<0.05 *	0.08 ± 0.02	<0.05 *
Phenols	<0.02 *	0.66 ± 0.07	<0.02 *	0.065 ± 0.07	0.45 ± 0.03	0.54 ± 0.05	0.189 ± 0.03	0.48 ± 0.02	0.33 ± 0.01	0.87 ± 0.02
Sulphates	143.98 ± 0.27	98.5 ± 0.29	96.94 ± 0.17	48.23 ± 0.21	98.31 ± 0.19	48.9 ± 0.26	97.92 ± 0.21	736.34 ± 0.29	196.5 ± 0.17	195.15 ± 0.17
Copper	3.34 ± 0.11	3.33 ± 0.08	3.28 ± 0.08	4.77 ± 0.07	4.81 ± 0.09	3.31 ± 0.11	3.32 ± 0.10	3.32 ± 0.10	4.31 ± 0.17	12.84 ± 0.11
Nickel	<2.0 *	<2.0 *	7.35 ± 0.12	16.42 ± 0.23	16.58 ± 0.12	16.48 ± 0.10	16.51 ± 0.13	16.56 ± 0.11	16.74 ± 0.10	31.22 ± 0.22
Zinc	26.02 ± 0.13	45.8 ± 0.24	24.04 ± 0.26	28.68 ± 0.19	106.68 ± 0.29	136.35 ± 0.27	166.96 ± 0.23	47.18 ± 0.17	153.87 ± 0.21	183.87 ± 0.23
PAH	0.19 ± 0.03	0.06 ± 0.01	0.42 ± 0.02	0.17 ± 0.03	0.05 ± 0.01	0.1 ± 0.01	0.15 ± 0.03	0.15 ± 0.03	0.08 ± 0.02	1.45 ± 0.08
Naphthalene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Phenanthrene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.02 ± 0.01	<0.01 *	<0.01 *	<0.01 *
Anthracene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.13 ± 0.03
Fluoranthene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Pyrene	<0.01 *	<0.01 *	0.31 ± 0.01	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.04 ± 0.02	0.55 ± 0.03
Benz(a) anthracene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.56 ± 0.01
Chrysene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.02 ± 0.01	<0.01 *	<0.01 *	<0.01 *
Benz fluorantrain	0.19 ± 0.03	0.06 ± 0.03	0.11 ± 0.01	0.17 ± 0.01	0.05 ± 0.01	0.1 ± 0.01	0.11 ± 0.03	0.15 ± 0.03	0.04 ± 0.01	0.21 ± 0.07
Benz(a) pyrene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Benzo(ghi) perilen	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *
Indene pyren	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *

* Detection limit of the method; PAH, polynuclear aromatic hydrocarbons.

(for the last 5 points). From the analysis of the obtained concentrations, we observed the exceeding of the limits allowed for the following indicators: phenols, sulphates, zinc, anthracene, pyrene, benzoanthracene and benzfluoranthen, but the values were lower than the value of the alert threshold, i.e., the sensitive use category.

Out of a total of 121 analysis plots, 10 pollution-susceptible plots were identified, from which 20 samples were collected and analyzed.

In the samples from the sampling points S_9A and S_9S, in the area of the used oil storage of the Tismana I quarry, at approximately 3 m from the fixed oil storage containers, we observed the exceeding of the allowed limit values for phenols, sulphates, zinc, PAH, and benzfluoranten, but they did not exceed the alert threshold values, i.e., the sensitive use category.

Regarding the samples collected from the sampling points S_10A and S_10S, near the first house in the village of Arderea (compared to the perimeter of Tismana I), the exceedance of the limit values allowed for phenols, sulphates, zinc, PAH, anthracene, benzo anthracene, and benzfluorantene exceeded the alert threshold (i.e., the sensitive use category).

In the samples from the sampling points S_8A and S_8S, near the first house in Pinoasa village (compared to the mining perimeter Tismana I), it was shown that the limit values allowed for phenols, sulphates, zinc, pyrenees, and benzfluoranten were exceeded, but the alert threshold values were not exceeded (i.e., the sensitive use category).

For the soil samples collected at points 8 to 10, the values of the analyzed concentrates and the comparison with the normal values, alert thresholds (PA) and intervention thresholds (PI), by types of uses (sensitive and less sensitive), are given in the

Table 5. Analyzed chemical indicators, normal values, PA, and PI.

Quality Indicators	Soil Sampling Points (mg/kg su)						Normal Values	Alert Thresholds		Intervention Thresholds
	S8S	S8A	S9S	S9A	S10S	S10A		Types of Uses
Level	I Ss	II Depth 20 cm	I Ss	II Depth 20 cm	I Ss	II Depth 20 cm		Sensitive	Less sensit.	Sensitive	Less sensit.
Cadmium	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	1	3	5	5	10
Lead	<2.0 *	<2.0 *	<2.0 *	<2.0 *	<2.0 *	36.9	20	50	250	100	1000
Free cyanides	<0.05	0.18 ± 0.04	<0.05	<0.05	0.08 ± 0.02	<0.05 *	<1	5	10	10	20
Phenols	0.45 ± 0.03	0.54 ± 0.05	0.189 ± 0.03	0.48 ± 0.02	0.33 ± 0.01	0.87 ± 0.02	<0.02	5	10	10	40
Sulphates	98.31 ± 0.19	48.9 ± 0.26	97.92 ± 0.21	736.34 ± 0.29	196.5 ± 0.17	195.15 ± 0.17	-	2000	5000	10,000	50,000
Copper	4.81 ± 0.09	3.31 ± 0.11	3.32 ± 0.10	3.32 ± 0.10	4.31 ± 0.17	12.84 ± 0.11	20	100	250	200	500
Nickel	16.58 ± 0.12	16.48 ± 0.10	16.51 ± 0.13	16.56 ± 0.11	16.74 ± 0.10	31.22 ± 0.22	20	75	200	150	500
Zinc	106.68 ± 0.29	136.35 ± 0.27	166.96 ± 0.23	47.18 ± 0.17	153.87 ± 0.21	183.87 ± 0.23	100	300	700	600	1500
PAH	0.05 ± 0.01	0.1 ± 0.01	0.15 ± 0.03	0.15	0.08 ± 0.02	1.45 ± 0.08	<0.1	7.5	25	15	150
Naphthalene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.02	2	5	5	50
Phenanthrene	<0.01 *	<0.01 *	0.02 ± 0.01	<0.01 *	<0.01 *	<0.01 *	<0.05	2	5	5	50
Anthracene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.13 ± 0.03	<0.05	5	10	10	100
Fluoranthene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.01 *	<0.02	5	10	10	100
Pyrene	<0.01 *	<0.01 *	<0.01 *	<0.01 *	0.04 ± 0.01	0.55 ± 0.03	<0.02	2	5	5	50

* Detection limit of the method; PAH, polynuclear aromatic hydrocarbons.

.

As seen in Table 5, only in the test plots S₈, S₉ and S₁₀ we identified a pollution with phenols, Ni, Zn, PAH, and pyrenes which exceeded the normal values both at the surface of the soil and at a depth of approximately 20 cm. All the values did not reach the alert or intervention threshold.

Graphical representation of the variation of concentrations of Zn (Figure 4a) and other heavy metals (Cd, Pb, Cu and Ni), sulphates and phenols in comparison with the normal value, PA, and PI (for less sensitive soils), for soil samples collected at points 8, 9 and 10 on the two levels (at the surface and at 20 cm deep) is shown in Figure 4b,d.

4. Discussion

The mining activity effectively destroys the natural geological environment, and the impact of soil and subsoil pollution is related to the risk of accidents or other disasters during mining that may occur. This is especially the case for soil, for which it is difficult to explicitly detect only the effects of those pollutants in its degradation [1,15,16,17,18], but their potential synergistic interactions (even at low individual concentrations) are not known.

Analyzing the obtained concentrations, we can observe the exceeding of the limits allowed for the following indicators: phenols, sulphates, zinc, anthracene, pyrene, benzo anthracene and benzo fluoranthene, but the values are lower than the value of the alert threshold, i.e., the sensitive use category.

In the samples from the sampling points S_9A and S_9S in the used oil storage of the Tismana I quarry, at approximately 3 m from the fixed oil storage containers, the was an exceeding of the allowed limit values for phenols, sulphates, zinc, PAH, benzofluoranthene, but these did not exceed the alert threshold values, i.e., the sensitive use category.

Regarding the samples from the sampling points S_10A and S_10S near the first house in the village of Arderea (compared to the perimeter of Tismana I), there was an exceedance of the limit values allowed for phenols, sulphates, zinc, PAH, anthracene, benzo anthracene, and benzo fluoranthene, but the values did not exceed the alert threshold, i.e., the sensitive use category.

In the samples collected from the sampling points S_8A and S_8S, near the first house in Pinoasa village (compared to the mining perimeter of Tismana I), there was an exceedance of the allowed limit values for phenols, sulphates, zinc, pyrene, and benzo fluoranthene, but the alert threshold values were not exceeded, i.e., the sensitive use category.

The high values of the concentrations of CD, Zn, Cu, Ni, Pb present in the soils affected by career exploitation, in certain sampling points, were exceeded. Their presence in the organic layer at the soil surface and 20 cm deep indicates the great influence of industrial activity and large deposits containing metals in the Rovinari basin area. The concentration of heavy metals identified in the soil profile decreases with the depth in the checks on the high accumulation of these elements in the organic and organic-mineral plant layers [15,19,20,21,22]. This is due to a large capacity of absorption and accumulation of heavy metals of organic materials and mineral soil complexes [22,23]. The values of the cadmium concentration in all the sampling points were exceeded. The concentration of cadmium is one of the factors that could cause contamination, because cadmium is one of the most movable elements in the heavy metal group. The normal value of the concentration of cadmium is 1 mg/kg, and from the measurements it was found that in each sampling point it was 50% higher than the normal value.

There are interactions between contaminants, the soil matrix and the biota [24]; in this sense, the choice of a method of rehabilitating soil affected by mining was thought to be by creating a leisure park, which would attenuate the effects of contaminants by bioaccumulation. To monitor the effects of the contaminants, bicomponent species were chosen for heavy metal pollution [17,22,25].

Possibilities for the Ecological Reconstruction of the Tismana I Quarry

Ecological rehabilitation is a “green and sustainable remediation” method, as it solves various environmental problems. The ecological remedy is defined as “the process of examining all the environmental aspects of the remedy implementation and the combination of options to optimize the net benefits for the cleansing actions” by the USEPA Environmental Protection Agency (USEPA) [25,26].

A wide variety of methods can be used to eliminate heavy metal contamination. Traditional technologies have been used to plant seedlings raised in vegetation vessels with fertile soil at the root, with a 2-year maturity, which has proven to be effective and low cost. For the immobilization of heavy metals, species capable of accumulating heavy metals from the soil were chosen.

The creation of new green areas, and the protection, conservation, and expansion of existing ones, is an important means of combating the action of pollutants and improving the living environment of people (Figure 5). Forests and any kind of green space have an essential ecological role as large producers of the oxygen necessary for life, and they contribute to reducing physical, chemical, and microbial pollution by creating a favorable microclimate, acting directly on the extreme values of various environmental factors (temperature, wind, and atmospheric humidity).

The afforestation of degraded lands can be achieved through a judicious choice of species, economically oriented and naturalistically based, based on detailed knowledge of seasonal conditions.

Knowing, on the one hand, the ecological complex of the resort and, on the other hand, the requirements and tolerances of the woody plants, it is easy to proceed to choose the assortment of species when the forest culture is installed. In the case of native species, a local origin is always preferred, because they grow in optimal conditions and make better use of the productive potential.

On the degraded lands from the Tismana quarry, following the seasonal studies carried out, the types of species which are able to make the most of the values of the seasonal environment and to fully meet the economic requirements were chosen. Thus, for the creation of a recreation forest from the Tismana I quarry, the following species were chosen: Ulmus glabra, Tillia tomentosa, Robinia pseudoacacia, Eleagnus angustifolia and Fraxinux ornus (Figure 6).

The research carried out led to the conclusion that the density of crops is closely related to the time when the state of the massif is achieved, which is a particularly important element in reducing and stopping erosion processes. In order to obtain a satisfactory protective effect, the closure of the massif must be ensured in most cases until the age of 10 years.

For excessively eroded land, the density of silver fir crops is 5400 seedlings per hectare, and for acacia crops it is 6700 seedlings per hectare. The afforestation formula shows the percentage area occupied by the species used. For each species, the density of the seedlings was determined according to the creditworthiness of the resort and the closure of the massif (

Table 6. Density of the seedlings.

Type of Land	Afforestation Formula	Type of Species	Surface Excessively Eroded Land (ha)	Density Seedlings/ha
For excessively eroded land	40% Ul + 30% Sc + 30% Te	Ulmus glabra (Ul) Robinia pseudoacacia (Sc) Tillia tomentosa (Te)	740.5	1332,900 1488,405 999,675
The protection curtains	60% El.a. + 40 Mj	Eleagnus angustifolia (El.a.) Fraxinux ornus (Mj)	740.5	1110,750 740,500

).

In order to create the protection curtains, the thickness is determined according to the favorability of the resort and the time required for the closure of the massif. The density of the willow culture mixed with blueberries for protection curtains is 2500 seedlings/ha.

Of all the species used, acacia generally has the greatest potential for maintenance and development. Consequently, it must continue to be the main species in the afforestation formulas in most areas, namely those that are subject to rain erosion of all degrees, or landslides with or without the fragmentation of the displaced land mass. It is, in fact, one of the few species that manage to regenerate at a young age.

Among the species associated in the acacia formulas, under the conditions shown above, the willow gave the best results. In conclusion, we support the maintenance of this species in culture. While the acacia depletes the soil, the willow enriches it with nitrogen, thanks to the nitrifying bacteria with which it lives in symbiosis.

Remediation is considered to be the management system of contaminated sites to prevent, minimize and reduce damage to human health, properties/buildings [27,28], or the environment. Phytoremediation uses plants to extract, accumulate and/or detoxify pollutants. This is an efficient, non-invasive, cost-effective method, and is aesthetically pleasing and socially accepted for the remediation of polluted areas [29,30]. Plants are ideal soil and water remedies due to their genetics and biochemical and physiological properties.

The major advantages of phytoremediation techniques compared to physico-chemical remediation technologies include:

■

the possibility to generate less secondary waste;

■

minimal degradation of the environment;

■

the possibility to leave the soil in place, and in conditions of use after treatment;

■

low design costs for land candidate for remediation;

■

requiring very little technique, because the implementation requires little more than the basic physico-chemical techniques;

■

the possibility of alternately placing accumulating species that are considered resistant species with sensitive species, e.g., Eleagnus angustifolia and Fraxinuxornus, with the sensitive species Tillia tomentosa, Ulmus glabra and Robiniapseudoacacia.

Disadvantages of phytoremediation techniques include:

■

the long time required (over 10 years of growth);

■

the limited depth to which it can be applied (1.2 m for the soil) because the roots can only effectively clean a limited depth;

■

the possibility that pollutants may enter the food chain through animal consumption of plants;

■

the fact that the operating characteristics and costs for a large scale of implementation have not yet been fully assessed;

■

plant residues which may require disposal as hazardous residues, or require additional treatment;

■

the fact that degradation by-products can be mobilized to groundwater or bioaccumulated in animals;

■

the possibility that if the concentration of contaminants is too high the plants may die;

■

the fact that plant growth can be seasonal depending on the location;

■

the climatic and hydrological conditions (e.g., floods, drought), which may restrict the growth rate of the type of plant that can be used;

■

the fact that the surface of the local land can be modified to prevent floods or erosion;

■

the fact that soil amendments may be needed, including chelating agents to facilitate the uptake of pollutants by plants by breaking the bonds between contaminants and soil particles.

5. Conclusions

The impact produced by the current coal mining activities in the Tismana mining perimeter on the soil / subsoil is a long-lasting local and zoned impact in area and volume, and refers to the following:

-

The quality of the soil environmental factor in the mining and scrap mining perimeter is totally negatively modified by the direct and related coal mining activities. The same situation is found in the subsoil, where the mining activity effectively destroys the natural geological environment.

-

The potential environmental impact of the soil and subsoil is related to the risk of accidents or catastrophes related to:

• the risk of environmental accidents that could cause the self-ignition of coal in the layer or in the surface deposits;
• accidents or catastrophes leading to major disturbances of the geological environment, mixtures of aquifers, and penetration of pollutants from the surface;
• the adoption of organizational measures and exploitation technologies which do not limit the effective action “in situ” to that which is strictly necessary, and which are not adapted to the specifics of the local geological structure; this can generate an amplification and diversification of the complexity of the effects of coal on the ground and subsoil;
• the local accentuation of the instability of the geological strata, favoring landslides and settlements.

In order to eliminate the pollution of the environmental factors due to the exploitation activity in the Rovinari mining perimeter, we chose as a case study the Tismana I quarry (740.5 ha), where we proposed the establishment of a recreational forest. We made the choice of species in accordance with the native ones, and when restoring the landscape, the observance of the architecture of the neighboring landscape was considered. The planting of trees and shrubs will be carried out in pits. Seedlings will have root loan soil for quick installation. Paths and access roads through the forest will also be arranged, which can be the career steps. The results obtained contribute to the identification of pollution sources by providing an overview of the time when the studies were conducted in correlation with the environmental, economic and land use issues in the area analyzed, as a starting point for subsequent studies.