Introduction

While the mining industry makes significant contributions to a nation’s economy, it also causes the emission of hazardous substances into the environment (Flores de la Torre et al. 2018). If the release of these potentially toxic elements (PTEs) is not controlled, it can result in the contamination of various environmental matrices, including soil, surface water, and groundwater. This situation poses a serious threat to the environment and public health (Hadjipanagiotou et al. 2020). Soil is one of the world’s most indispensable resources and plays a fundamental role in creating vital ecosystem services by connecting natural processes (Khan et al. 2022). Soil quality is generally defined as “the capacity of a soil to function within characteristic or controlled environmental limits, provide ecosystem services, maintain plant and animal productivity, protect or enhance water, and support human health and habitat.”(Golia 2023), Anthropogenic activities such as mining, steel industry, waste incineration (including sludge processing management, control of acid discharges and ashes) and poor management of electronic waste (e-Waste) deteriorate soil quality by causing uncontrolled introduction of metals and metalloids into the soil (Quintero-Payan et al. 2024). Metal and metalloids-related soil and water contamination have become a significant problem in many regions of the world (Khafouri et al. 2021). The release of metal and metalloids into the soils of mining areas and their surroundings leads to significant increases in their concentration, with devastating effects on the ecosystem’s function and structure (Cheng et al. 2022).

Many metal and metalloids, including Zn, Cu, and Se, are necessary for the regular development of plants and other living things. Other metals that are not basic elements, such as Pb or Cr, can be tolerated by the ecosystem at low concentrations, but these metal and metalloids can become toxic at higher concentrations (Srinivasa Gowd et al. 2010). Indeed, metal and metalloids pollution from mines is considered to be a contributing factor to deforestation (Sousa et al. 2012) and reduced biodiversity and aesthetic appearance of forests, and they cause economic losses as these areas tend to lose their suitability for agriculture (Pehlivan et al. 2021). Therefore, the determination of soil pollution levels and the assessment of metal and metalloids pollution in abandoned mines are important environmental issues (Loska et al. 2004).

Mining operations can cease for multiple reasons, including increasing costs, depleting reserves, shifting ore grades, environmental effects, and geological causes (Horasan et al. 2021). Damage to the environment can continue to occur even many years after mine closure, and indeed this is being recognized as one of the main sources of pollution worldwide. These abandoned sites are a source of environmental pollution from high levels of metal and metalloids with toxic effects on surface waters, living organisms, and soils (Beane et al. 2016). Waste from copper (Cu) mines may contain other elements besides Cu, such as As, Cd, Co, Cr, Mn, Ni, Pb, and Zn, all at various concentrations depending on the mining method that was used (Karczewska et al. 2015). These elements accumulate in the soil and are transferred to the plant by the plant’s roots. In polluted areas, the leaves of tree species are considered to be accumulation monitors, in which significant amounts of metal and metalloids and other pollutants accumulate on the leaf surface (Madejón et al. 2006). Pine trees, especially their needles, can be used to measure metal and metalloids pollution in the environment (Pająk et al. 2015). Long-lived organisms, such as trees, can grow in soil with highmetal and metalloids concentrations due to resistance mechanisms, including ectomycorrhizal symbiosis. As a result, the Scotch Pine (Pinus sylvestris L.) and Silver Birch (Betula pendula Roth.) are the species most frequently used on polluted soils in Eastern Europe (Bierza et al. 2020). Scotch pine is characterized by the fact that it easily assimilates various elements and has a lower tolerance to environmental pollution compared to other conifers. Scotch pine is considered a useful bioaccumulator and model tree for pollution monitoring studies (Klink et al. 2018). Such trees are useful because high concentrations of metal and metalloids adversely affect soil quality and destroy functional ecosystems, resulting in otherwise barren lands devoid of vegetation (Chileshe et al. 2020).

For the past decade, the USEPA (United States Environmental Protection Agency) model has been widely used in assessing the health risk of soils in the vicinity of copper mines (Chen et al. 2022). For this reason, it is necessary to determine the levels of these PTEs to determine the environmental effects of abandoned mining sites and to take precautionary measures (Covre et al. 2022). The enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), ecological risk index (ERI), pollution load index (PLI), and human health risk index, as well as various indices such as bioconcentration factors (BCFs), were used to evaluate the potential pollution level of these PTEs in soil and plants (Hakanson 1980; Men et al. 2018; Ferreira et al. 2022; Steingräber et al. 2022; Bayraklı et al. 2023).

Metal and metalloid contamination in soil associated with mining activities is a major problem worldwide. Abandoned mine sites are associated with environmental risks and mining waste has been uncontrolled. A case study was conducted at the Jerada coal mine site in Morocco and soil and coal mine waste rock were sampled. The results show that coal mine waste rock is associated with soil contamination (Khalil et al. 2023). Another study evaluated trace element contamination in soils and stream sediments at an abandoned traditional gold mining site in Cameroon. Analyses of samples collected from the surrounding area of the abandoned mine site used geochemical background and geo-accumulation indices to discriminate between natural and anthropogenic enrichment. As a result, the abandoned mine site was found to be the main source of soil and stream sediments with high levels of cadmium, lead and zinc, which may be hazardous to human health (Paternie et al. 2023). Another study investigated the levels and sources of heavy metal pollution around the Selibe Phikwe copper mine. It was found that the area was moderately polluted with heavy metals. However, it was emphasized that this pollution could increase in the future and cause serious impacts on the soil environment and food chain (Motswaiso et al. 2019). Similarly, research from around the world shows that mining activities increase concentrations of metals and metalloids in soils, resulting in environmental impacts.

Copper mining has a long history in Türkiye. Artvin province, located in the east of the Eastern Black Sea metallogenic mineralization, is an extremely important region for metallic mines. Artvin Kuvarshan copper mine, which was among the very first copper mines to operate in Türkiye, was first developed by the German company B. Simens in 1905. Suspending its activities in 1917, the enterprise was revisited by Citibank in 1937 and a total of 232,800 tons of ore was extracted, with 8815 tons of pure copper production, between 1937 and 1941. It was finally closed in mid-1945 due to the depletion of reserves.

There are two types of mineralization in the Kuvarshan copper mine, which is located in the east of the Çoruh region and has vein-type mineral reserves. The first type of mineralization is located in the upper part and is defined as poor pyritic mineralization (gelberze). Containing 1.5% Cu, this ore structurally contains pyrite, chalcopyrite, and galena. The second type of mineralization is located below and is defined as copper-rich mineralization (grauerze). Containing 6–7% Cu, this ore is structurally composed of chalcopyrite, bornite, neodigenite, chalcocite, sphalerite, and secondary galena and tennantite (Kovenko 1942). The ore extraction process in the mine site was carried out through closed galleries and processed in the smelting facility of the enterprise, where blaster copper production was carried out (Dogangün Yasa and Yardımcı 2022).

In general, the effects of abandoned mining sites on the environment have been studied in Kuvarshan. Many previous studies have examined its high concentrations in water and mine waste in abandoned mine sites. However, to date, soil and vegetation pollution around abandoned mine sites has not been adequately investigated due to a lack of accurate data and information. In fact, understanding the sources and characteristics of mine pollution in Kuvarshan may provide useful information for the implementation of rehabilitation projects for abandoned mines and assist decision-makers in the development of new policies for the remediation of mines.

The abandoned mining site in Kuvarshan was chosen to evaluate the impact of mining activities on the surrounding soils and vegetation. The objectives of this study are as follows: (1) geochemical and mineralogical characterization of soil samples; (2) the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), ecological risk index (ERI), human health risk index (BCF), and plant enrichment factor (EFPlant) values of selected chemical elements in soils and (3) determination of plant accumulation indexes in plant samples.

Materials and methods

Data collection

Research articles in recent years have mentioned the presence of toxic elements in most samples from soils near copper mines. These include Cu, As, Zn, Pb, Cd, Ni, Mn, and Cr. These elements are in the priority pollutant class, as determined by the USEPA, and can accumulate in the topsoil through both natural and anthropogenic sources (**s of abandoned mine site study area

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Fig. 1
figure 1

a) The location of the study area, b) photograph of the Kuvarshan smelter, c) study area and d) mineral dacite and waste heap waste area

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Analysis of plant and soil samples

Soil samples collected from the field were dried for 10 days until they were air-dry and homogenized by passing through 2 mm sieves. Classification of soil samples by particle size was conducted using the Bouyoucos hydrometer method, pH and conductivity measurements by the 1:2.5 soil water suspension method, total lime using a Scheibler calcimeter, and aggregate stability (AS) by the wet sieve method (Fernández-Caliani et al. 2009).

The plant samples (leaves and needles) collected in the field were washed three times with distilled water, clearing particles from them, and dried at 60 °C for 48–60 h until they reached a constant weight. The weighed plant samples were homogenized by pounding with a pestle and stored at 4 °C until analysis (Dary et al. 2010).

Soil and plant samples prepared for multi-elemental analysis using inductively coupled plasma optical emission spectroscopy (ICP-OES; Perkin Elmer Optima 8000) were weighed in different amounts, placed in Teflon containers, and extracted by applying the microwave decomposition method (Table 2).

Table 2 Digestion methods and metal determination with ICP-OES
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After the degradation process, a 1 mg/L internal standard (Yttrium) was added to all samples, and the final volume was supplemented to 50 mL. Metal concentrations (As, Zn, Pb, Cd, Ni, Fe, Mn, Cr, Cu, and Al) in soil and plant extracts were analyzed using ICP-OES. Standard deviations were determined from three replicates of each sample. In addition, arsenic in plant samples was determined by hydride production and ICP-OES (Masson et al. 2006).

Analytical procedure

This procedure was used to determine its validity for the quantitative analysis of metal ions in plant material and soil. Optimization studies for the procedure were performed through precision or reproducibility, and calculation of relative standard deviation and limits of detection (LOD) and quantification (LOQ).

To determine the accuracy of soil and plant samples, standard reference materials CRM027 (Sandy Loam 10) and ERM-CD281 (Rye Grass) were used in accordance with environmental conditions, metal and metalloids contents, and texture. The values given for both standard reference materials were compared with the certificate values, and the accuracy of the method was given in Table 3 together with the recovery percentages. In addition, the LOD (the smallest concentration of the analyte) and LOQ (the smallest concentration at which the analyte is quantified) were calculated according to the International Union of Pure and Applied Chemistry (IUPAC) for the method used in the study. According to this method, LOD and LOQ values for each metal were obtained by multiplying the standard deviation of the method blank measurements by 3 and 10, respectively (Thompson et al. 2002). However, the matrix effect that may occur during the measurements was minimized by using the internal standard Yttrium (Masson et al. 2006).

Results of precision and accuracy analyses

According to the obtained results, the recovery values for each metal were found to be between 80 and 120%, demonstrating the accuracy of the method (Shabanda et al. 2021). Additionally, repeatability or precision was determined by calculating the relative standard deviation, which was found to be below 10% for all the metals. These results indicate the suitability of the selected extraction method in terms of precision and accuracy within a 95% confidence interval (Table 3).

Table 3 Accuracy and precision of metal and metalloids
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Statistical analysis

Analysis of all data was carried out using SPPS version 26.0. Since the variances of the soil and plant samples were not homogeneous, the differences between the groups were compared using the Kruskal-Wallis test, and the relationship between the physical and chemical analytes and the metals was tested using Spearman-Brown correlation analysis.

Soil pollution and risk assessment indexes

In order to evaluate the metal and metalloids (As, Zn, Pb, Cd, Ni, Fe, Mn, Cr, Cu and Al) pollutions measured as a result of the analysis of topsoil (0–30 cm) samples collected from 40 points, enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), ecological risk index (ERI), human health risk index has been calculated. The detailed information is given as supplementary material.

Determination of plant element uptake and bioaccumulation performance

Plant samples were collected from 33 points in the abandoned mine site. Bioconcentration factor (BCF) and plant enrichment factor (EFPlant) were calculated in these plant samples. The formulae used in the calculations are provided in the supplementary material.