Introduction

Copper (Cu) is widely recognized as a significant metal for contemporary society, technology, and infrastructure, taking its place as the third most crucial element, following iron and aluminum (Sverdrup et al. 2014). The need for Cu resources has been steadily growing due to rapid growth of the world’s economy and industrialization (Buayam et al. 2019). Cu is a widely used metal in various industries, including electrical, automotive, and household sectors. Additionally, it has gained recognition for its antimicrobial properties, making it an effective surface in recent times (Elguindi et al. 2011). It is believed that human civilizations initially utilized this metal since it could be found in the native, metallic form, eliminating the need for smelting (Grass et al. 2011).

The majority of Cu deposits are extracted through open-pit mining, while underground mining methods are used less frequently (Berger et al. 2008). To produce 1 ton of copper, the typical process involves excavating and crushing over 150 tons of ore. The ore is then concentrated through froth flotation and extracted via various methods, which depend on whether the ore is sulfide or non-sulfide in nature (Wills and Napier-Munn 2006). The entire process generates significant quantities of tailings, which are the remnants of the ore after copper extraction. These tailings contain elevated levels of PTEs such as Zn, Pb, Fe, Cd, as well as metalloids like As. These harmful substances can be transferred to both aquatic and terrestrial ecosystems, impacting trophic circuits, biodiversity, water, sediments, soils, and human health (Baycu et al. 2015; Rzymski et al. 2017). In addition, the discharge of acidic water from mines, commonly referred to as acid mine drainage (AMD), contributes to the release of harmful components that are dissolved from rocks exposed to water with a very low pH. This process is predominantly caused by the oxidation of iron sulfide (Akcil and Koldas 2006; Rouhani et al. 2023a).

There is a significant risk of pollution from mining operations to the nearby environment. If waste materials from mining activities are improperly disposed without the implementation of proper monitoring systems, there is a considerable risk that pollutants will be dispersed into the nearby soil adjacent to the mine by wind, water, and rainfall (Boussen et al. 2013; García-Lorenzo et al. 2012; Wang et al. 2009). There can be significant increases—up to three times—in the content of several PTEs in the soil near mining sites. Owing to their extended stability in the soil and subsequent uptake by flora and fauna through plant consumption, these compounds pose a significant threat to human health as well as ecosystems. This risk is most noticeable in situations where mining operations are located near agricultural areas (Álvarez-Ayuso et al. 2012; Boussen et al. 2013; Khazaee et al. 2015).

To manage the discharge of PTEs into the environment, soil remediation strategies have been developed with some strategies still evolving. Phytoremediation has received significant interest from researchers as an easily applicable eco-friendly, and effective technique for soil remediation (Sytar et al. 2019; Nsanganwimana et al. 2021). Employing plants as a treatment method to remove pollutants from the environment is known as phytoremediation. The application of plants to eliminate pollutants is an environmentally friendly method that does not disturb the ecosystem, as it does not adversely impact topsoil (Erickson & Pidlisnyuk 2021). The most important step to successfully use plant-based remediation for polluted soils and mine tailings is the selection of appropriate hyperaccumulators (van der Ent et al. 2024). Hyperaccumulator plants have the potential to extract, accumulate, and endure elevated concentrations of PTEs. These plants can accumulate PTEs in their roots and shoots, by phytostabilization and phytoextraction, respectively. Phytostabilization comprises the immobilization of contaminants within the soil, whereas phytoextraction encompasses the utilization of plants to extract/remove contaminants from polluted soil (Erickson & Pidlisnyuk 2021; van der Ent et al. 2024). However, it is important to take into account that mining areas are not conducive for vegetation growth, due to issues such as low water availability, unfavorable pH, high concentrations of harmful PTEs, and low levels of organic matter and nutrients (Borbón-Palomares et al. 2024).

The mining and processing of Cu ore have a significant environmental impact, particularly due to the large volume of tailings left over after extracting copper from the ore, which poses serious environmental risks due to their high levels of toxicity from PTEs. According to the existing literature, there is a limited number of review studies that were conducted to investigate the prevalence and distribution of PTEs in Cu mining regions, as well as the remediation approaches employed worldwide. Thus, there is limited information available for PTEs and their successful remediation from the many Cu mining sites in Iran. With this background, the objective of the present review study is to understand and highlight the distribution of metals and major polluting PTEs in Cu mining areas from Iran. The study further assesses the remediation strategies applied in these areas.

Cu mines in Iran

Iran has a rich history of mining and associated industries. The country possesses a diverse range of mines, some of which have a history spanning thousands of years. In Iran, a transition from unscientific to scientific and systematized ore extraction occurred around 1847, marking the distinction between scientific and non-scientific mining periods (Pezeshkan et al. 2005). Currently, ownership of Iranian mines is divided between private and public (governmental) sectors. In general, mines that are controlled by the private sector are smaller in size and have less environmental risks in comparison to mines controlled by the government. Government-controlled mines, on the other hand, are usually bigger and often need a processing plant, particularly for minerals including lead, zinc, gold, copper, etc. (Monjezi et al. 2009). Unfortunately, there is only limited information available in the existing literature about Cu mining in Iran. Information about some of the most important copper mines in Iran presented further.

The Sarcheshmeh copper deposit, which has 1 billion tonnes with an average copper content of 0.9%, is regarded as the fourth-largest mine in the world. This ore body is situated in the southeastern region of Iran, specifically in Kerman province (Banisi and Finch 2001). Mining activities have been in progress at the copper mine complex since 1972, resulting in a significant increase in copper extraction from 15,000 to 70,000 tonnes. Copper mining has usually utilized both pyrometallurgical and hydrometallurgical methods for processing sulphide minerals (Sadeghi Pour Marvi et al. 2016). Open pit mining is utilized to extract Cu deposits in Sarcheshmeh, with approximately 40,000 tons of ore extracted daily (Banisi and Finch 2001). Biochemical and mechanical manipulation and processing of minerals have generated significant amounts of AMD, dust, and tailings (Sadeghi Pour Marvi et al. 2016). The Darrehzar porphyry copper mine is situated to the south of the Uromieh-Dokhtar volcano-magmatic belt, specifically in the southeast Dehaj-Sarduyeh volcano-magmatic belt. It is located approximately 10 km south of the well-known Sarcheshmeh porphyry copper mine in Kerman province. The deposit consists of 49 million tons of ore with a grade of 0.64% Cu and 0.004% Mo (Soltani et al. 2014). The Uromieh-Dokhtar magmatic belt is globally recognized as a significant area for copper deposits. The Alpine-Himalayan collisional orogenic belt extends from western Europe to Turkey, passing through Iran and extending into western Pakistan (Shafiei et al. 2008). The Porphyry copper mineralization found at Darrehzar has an association with granodioritic intrusive rocks from the Miocene period. These rocks are located within volcano-sedimentary rocks from the Eocene period and carbonate rocks from the Cretaceous period (Derakhshani and Abdolzadeh 2009; Soltani et al. 2014).

Sungun Cu Mine has been in operation since 2008 and it is the largest open-pit copper mine in northwest Iran (Nasrabadi et al. 2009). The porphyry deposit is situated in the East Azarbaijan province of Iran, specifically on the Alp Himalaya international metallurgical belt. It is located approximately 105 km northeast of Tabriz. This deposit is well-known for its vast reserve of sulfide copper ore, estimated to be nearly one billion tons (Rezaei et al. 2020). Sungun porphyries are belonging to Oligo-Miocene age and have erupted into upper Cretaceous carbonate rocks along with various types of Eocene erinaceous-argillaceous rocks, pyroclastic rocks, and lavas (Calagari 2003). Ore deposits and extraction facilities have been situated within the Arasbaran forest; an environmentally protected area that has been formally declared by UNESCO as a Natural Heritage site (Aghili et al. 2018).

Baychebagh copper mine is situated adjacent to the town of Mahneshan, approximately 160 km west of Zanjan. The existence of underground mine workplaces, an extensive system of production galleries, as well as other mining facilities, are indicative of a long period of production. The district contains numerous prospect pits and mining tunnels, which have led to the excavation of over 5.6 km of exploration tunnels and 3.6 km of tunnels from nine large ore veins, measuring 20–50 cm in width. Cu production in this mine is about 215,000 tons, with ore reserves estimated to be approximately 12 million tons. Before World War II, ore processing facilities have been established and employed. The Baychebagh deposit is a type of polymetallic massive sulphide ore deposit. It is found within a series of volcano-sedimentary complexes that are part of the Sanandaj-Sirjan volcanic belt. This belt offers substantial economic importance due to its considerable mineral potential and confirmed reserves of copper ore (Ghazban et al. 2015). The distribution of the various Cu mines in Iran are presented in Figs. 1 and 2.

Fig. 1
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Map of copper mine areas in Iran

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Fig. 2
figure 2

(Source: Eisa Mohammadi 2023)

Sarcheshmeh copper mine in SE Iran

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Potentially toxic elements

Earlier investigations revealed that along with Cu many PTEs, including As, Cd, Cr, Mn, Ni, Pb, and Zn, accumulate in the topsoil surrounding Cu mines (Bidone et al. 2001; Hadjipanagiotou et al. 2020; Sun et al. 2023; Radi et al. 2023). These PTEs have the potential to persist in soils for a long period, causing potential adverse health effects to residents via the food chain and being exposed to soil contamination (Gustin et al. 2021; Rouhani & Shahivand 2020).

Several possible explanations exist for these findings. Firstly, excessive quantities of copper minerals, such as chalcopyrite, cuprite, covellite, chalcocite, and malachite, discharged into soil during mining activities. This is primarily caused by destructive mining processes and inadequate treatment of mineral waste residue and wastewater (Alizadeh et al. 2024; Punia 2021). Cu-tailing dams also contribute significantly to Cu contamination of soil (Das and Maiti 2008). Secondly, mining activities generate substantial quantities of slags and aerosols, which are by-products containing various pollutants such as Zn, Cd, As, Pb, and Cu, are major contributors to soil pollution with PTEs (Izydorczyk et al. 2021). In addition, minerals often contain associated contaminants including Zn, Pb, Cd, and As coupled with Cu. During the process of excavating ore, metallurgical dust is released, which contains elevated levels of these hazardous elements. Consequently, these contaminants migrate into the surrounding soils (Radi et al. 2023; Izydorczyk et al. 2021).

Acid mine drainage (AMD) occurs when pyrite and other sulfate metals (such as tailing pits and dams open exposed cuts, and ore and waste-rock piles) oxidize due to exposure to air and microbial activity in mining areas. Numerous studies have demonstrated the critical role that water plays in the distribution and mobility of PTEs in the vicinity of mining sites (Han et al. 2017; Liao et al. 2016; Rouhani et al. 2023b). High levels of PTEs and sulfate, as well as low pH values, are features associated with AMD. Furthermore, as prior studies have shown (Kefeni et al. 2017; Xie et al. 2018), the corrosive properties of AMD interact with rocks that contain mineral ores, causing PTEs to dissolve and subsequently elevating their concentrations in nearby water streams and soils.

The variation in pollutants between global Cu mining sites can be attributed to the diverse geological conditions and methods used to extract Cu mineral resources (Nirola et al. 2016). Additionally, the type of Cu mining practices (such as waste disposal techniques, opencast working, and underground mining) has a direct impact on the discharge of hazardous metals (such as Cu and Cd) to nearby soils (Radi et al. 2023; Izydorczyk et al. 2021). The concentration of PTEs in topsoil may also be strongly impacted by distance between sample locations and centers of Cu mines (Koz et al. 2012; Su et al. 2018). The distribution of PTEs in the copper mining area is influenced by climatic conditions, including wind, precipitation, and temperature. Particularly, the process of PTE transportation in Cu mining area is directly influenced by wind direction and intensity (Punia 2021; Mulenga et al. 2022). Furthermore, the distribution of PTE in soils associated with Cu mines was found to be affected by variables such as exploitation methods soil properties, and site use (Alizadeh et al. 2024).

Soil PTEs impact on human health

The dispersal of PTEs within the mine and its surrounding areas poses significant environmental and potential public health issues. Exposure to high concentrations of PTEs poses a threat to the environment due to the acute and chronic toxicity it causes in microorganisms (including soil fauna), aquatic organisms, animals, and plants (Gutiérrez et al. 2016). Human health implications are the adverse impacts that occur when individuals are directly exposed to PTEs through contact with their skin, ingestion or inhalation of polluted particles. Indirect exposure can also occur when PTEs are ingested through food chain (Tepanosyan et al. 2018; Rouhani et al. 2022). Epidemiological studies have discovered a connection between Cu mining activities and various diseases, such as cancer, renal failure, liver cirrhosis, and headaches, in inhabitants living near copper mining areas (Izydorczyk et al. 2021). PTEs, such as Ni, Cr, Pb, and Cu, detected in soils adjacent to Cu mining sites, have detrimental effects on the lung, kidney, stomach, small intestine, and cardiovascular tissues of humans, potentially leading to the development of cancer (Yang et al. 2019). Similarly, exposure to As can have detrimental effects on human health, including skin cancer, panasthenia, respiratory system disorders, and renal failure (Paithankar et al. 2021). Children living near Cu mines are at a higher risk of being exposed to polluted soil in comparison to adults in the same area. This is because children may show certain behaviors, for example pica behavior (eating non-food items) and finger/hand sucking, which can increase their exposure to the polluted soil (Ghanavati et al. 2019; Filimon et al. 2021).

PTEs in Cu mines in Iran

The study conducted on the pollution of stream water and sediments by the Sungun porphyry copper deposit in northwestern Iran revealed significantly increased levels of PTEs in samples analyzed. These increased concentrations of PTEs pose a potential risk to health of communities that directly utilize untreated river water for household uses and recreational activities. In the Sungun region, metal pollution, particularly by Ni, Pb, Mo, and Cu, was a major factor in the sediments, which highlighted the necessity of additional research to determine the long-term impacts of pollutants, as well as waste dumps, and tailing dams, on the sediment chemistry (Moore et al. 2011). In a more recent study, the spatial distribution and vertical variations of PTEs in the sediment of Pakhir River, located downstream of the Sungun copper mine in northwest of Iran have been assessed. The findings indicated that the highest level of contamination was detected in the sample taken from Pakhir valley, with Cu being the primary contributor to sediment contamination. The first 50 cm of the ground surface revealed the highest level of PTEs, which subsequently decreased in amount as the sediment depth increased (Aghili et al. 2018).

The average concentration of Cu in soil surrounding the Mazraeh copper mine in northwestern Iran was found to be twice as high as the global guideline values. This elevated concentration might be attributed to the collapse of the tailing dam, which happened as a result of severe rains in May 2009 (Shahbazi et al. 2013). Soil samples taken from the Sorkheh and Mazraeh Cu mining sites in northwestern Iran showed significant levels of contamination with As, as well as moderate contamination with Pb and Zn (Hoseinpour et al. 2020). Similarly, Petrović et al. (2021) reported significant levels of As within a Cu mining region located near Bor, Serbia. Mining activities in Darrehzar Cu mine deposit (Kerman, Iran) have resulted in contamination of water and sediments with Cu, Cd, and Mo (Soltani et al. 2014). The study conducted on PTEs contamination in water and sediments from the Ghalechay river, particularly in the Baychebagh Cu mine area, revealed moderate levels of Cu contamination in the sediments. Additionally, the sediments were highly contaminated with Pb and Cd (Ghazban et al. 2015). High levels of Cu and Se elements in soil surrounding the Taknar Cu mine (located in NE Iran) have been attributed to anthropogenic sources, primarily associated with mining and mineral processing activities (Khosaravi et al. 2020). Mining activities carried out at the Maiduk Cu Complex have resulted in a significant increase in the levels of Cd, Pb, and Cu detected in soil samples taken from Shahr-e-Babak in the Kerman province of Iran (Damangir et al. 2015). In another study, it has been found that the levels and distribution of PTEs (Pb, Zn, Mo) were higher in Meiduk Cu mine areas, where elevated levels were observed in areas adjacent to the mine pits and waste dumps, indicating that these locations are likely sources of metal contamination (Rezaei et al. 2019).

The primary cause of soil contamination by Zn, Pb and Cu in surrounding areas of the Sarcheshmeh Cu mining and smelter in southeastern Iran was emissions resulting from recently mining and smelting operations. These emissions eventually spread through atmospheric transport, leading to contamination of the surrounding soil (Shamsaddin et al. 2020). In a more recent study, it was evident that soil and sediment surrounding the Sarcheshmeh Cu mine were polluted with Cu, and pollution levels showed a decreasing trend from the mine site towards Rafsanjan city (Ganjeizadeh Rohani & Mohamadi 2022). Sedimentary systems surrounding the Dar-e-Allo Cu mine in Iran showed higher levels of Cu, S, and Mo pollution, with alarming contamination level of Cu in this area (Bavi et al. 2023). Similar results were obtained from two Cu mining areas in China. Soils surrounding the Dexing Cu mine in Jiangxi Province, China, were contaminated by several PTEs including Hg, As, Cd, Pb, Zn, Cu, and to some extent by Cr. In particular, the pollution caused by Cu posed a significant risk to the soil quality (Ni et al. 2023). In soil samples taken from a typical Cu mining city located in eastern China, it was found that Cu had the highest mean concentration of 184.29 mg/kg, followed by Hg, Cd, Tl, Ni, As, and Pb. About 54.2% of this study area showed moderate contamination levels of Tl, As, Cd, and Cu (Sun et al. 2023).

Based on Fig. 3a, 21 different elements were studied in soils around Cu mining areas in Iran and between them Cu, Cd, Pb, and Zn were the most frequent metals. Cu is the dominant contaminant in polluted soils of Cu mining areas in Iran, followed by Mo and Pb (Fig. 3b). As shown in Table 1, the majority of conducted studies were from Sarcheshmeh copper mine as it is the biggest and most important Cu mine in Iran. Although soils around the most important Cu mines have been studied, there are still some other Cu mines that have not gained attention for environmental impact assessment studies. The mean concentration of some PTEs in impacted soils by copper mining in Iran is presented in Table 2.

Fig. 3
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a Frequency of studied elements, b most pollutant elements in Iranian copper mining areas

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Table 1 Soil pollution studies conducted around copper mine areas in Iran
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Table 2 Mean concentration of some PTEs in soil from copper mining areas
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Similarly, studies done globally, PTEs that were identified as polluting elements in addition Cu included Pb, Cd, As and Zn. In a study on soil contamination nearby a Cu mine in Yedidalga (Northern Cyprus), it was found that 78.0% of the sampling locations were extremely polluted with Cu, additionally, 55.6% and 22.2% of the sampling locations were found to be moderately to extremely contaminated by Cd and Pb respectively (Barkett and Akün, 2018). High levels of Cd, as well as Cu and As, were detected in the agricultural soils surrounding the Dongchuan Cu mining area in China (Cheng et al. 2018). Agricultural soil and stream sediments in the vicinity of the Agrokipia abandoned Cu mine in Cyprus were found to be polluted with PTEs, more particularly by Li, Ag, Cr, Cd, Pb, Zn, and Cu. The contamination was primarily attributed to AMD and stream waters, as proven by the elevated levels of PTEs in both stream waters and sediments in comparison to background levels (Hadjipanagiotou et al. 2020). Soils impacted by Cu mining in Sibay city (Russia), were severely polluted by anthropogenic sources particularly by Zn, as a consequence of mining waste storage and proximity of a nearby mining and processing plant to this city. The unfavorable environment in this area resulted in the accumulation of PTEs, alterations in agrochemical characteristics, soil cover disturbance, and destruction of vegetation (Suleymanov et al. 2022). Significantly high levels of Cu and As were observed in tailings and surrounding soils of the Tamesguida abandoned Cu mine area in Médéa, Algeria. These levels were considerably higher than local soils, crustal average, and world average shale (Radi et al. 2023).

Applied remediation strategies

Issues resulting from mining or metallurgical-related PTEs are prevalent worldwide (Schreck et al. 2020). In addition, management of contaminated environmental spheres, particularly soil, is a globally important challenge due to its role as a natural reservoir for diverse contaminants (Pavoni et al. 2017). A wide range of technologies utilizing different chemical, thermal, electrical, physical, or biological processes have been assessed to determine their effectiveness in effectively and safely reducing or entirely eliminating PTEs from contaminated areas. The investigations that were conducted yielded both positive and negative results for every single strategy, as well as when the approaches were combined. Initially, the potential of various methods was assessed based on their effectiveness, duration, expenses, and any possibility of additional disruption to the treated matrix (Petrović et al. 2021). Based on existing literature, phytoremediation has been the sole strategy employed for soil amendment in copper mining areas in Iran so far. Most probably due to its advantages over other remediation strategies including low cost, its applicability, environmentally-friendly, etc.

In recent years, there has been significant progress in the application of phytoremediation technology for mitigating PTEs contamination in solid waste within mining regions. Soil phytoremediation is a widely studied topic comprising two primary strategies. The first strategy, known as phytoextraction, refers to metal absorption by plant roots, followed by their translocation and accumulation in aboveground biomass, specifically in shoots. The second strategy, phytostabilization, relies on special ability of root exudates to stabilize or immobilize metals in soil. Effectiveness of phytoextraction is dependent upon plant's ability to absorb and transport metals from soil to shoot, along with shoot’s capacity to accumulate these metals. Furthermore, the amount of green biomass formation also plays a significant role. Plants that show the highest potential for metal absorption or accumulation were identified within a relatively small group that are known as hyperaccumulators (Perlatti et al. 2015; da Silva et al. 2017; Shojaee Barjoee et al. 2023). The vast majority of hyperaccumulator plants that have been identified mostly belong to the group of herbaceous wild species. These plants are often found only in their native habitats and have low biomass yield, slow growth rate, and shallow root systems (Rascio and Navari-Izzo 2011). These plants, which are mostly small weeds, can tolerate and concentrate large quantities of PTEs in their aerial parts, allowing them to grow in metalliferous soils without showing any potential toxic impacts (Liu et al. 2018). Phytoextraction is associated with some challenges including the sustainable disposal of contaminated biomass and the possible transfer of PTEs to the food chain (Patra et al. 2020). Thus, phytostabilization of PTEs, using plant known as excluders may reduce challenges as there will be low chance of transfer of PTEs to the food chain and limited contaminated waste (roots only) as the biomass may be utilized.

Although, it is important to consider that absorption of metals from soil can be strongly influenced by several factors, including redox state, organic matter and clay contents, soil pH, etc. (Alloway 2013; Kabata-Pendias 2011), it has been widely understood that detecting metal levels in plant parts (such as roots) is not a reliable indicator of soil contamination (Alagić et al. 2018). Meanwhile, the concentration of metals in aboveground plant parts has been commonly utilized as a convenient method for assessing airborne contamination. Many biomonitoring investigations carried out in heavily polluted areas, including mining and metallurgical areas, have been depending on measuring metal concentrations in various plant parts (both washed and unwashed), including stems, branches, leaves, or shoots (Alagić et al. 2018; Khalid 2019; Schreck et al. 2020; Simon et al. 2011). Several researchers have pointed out that concentrations of metal in these regions are derived not only from contaminated soil but also from contaminated atmosphere. This knowledge has provided a strong foundation for conducting various thorough environmental quality evaluations, such as food chains quality in the areas of interest. In conclusion, it is worth noting that a variety of higher plants have frequently been observed growing well in the impacted regions. As a result, many researchers have utilized the various parts of these plants as cost-effective and easily available biomonitoring tools (Alagić et al. 2018; Petrović et al. 2021).

Phytoremediation studies in Cu mining areas in Iran have identified various different plants that have successfully remediated sites with various PTEs. Malayeri et al. (2008) investigated efficacy of accumulator plants for phytoremediation in soil contaminated by the Hame Kasi Cu mine in northwest region of Hamedan city, Iran. Their results showed that species of Verbascum speciosum, Chenopodium botrys, Cirsium comgestum, Scariola orientalis, and Cousin asp. are suitable high accumulator plants for mitigating Cu. Later, another study on this area revealed that Chenopodium botrys, Cousinia sp. and Ziziphora clinopodioides were the most efficient plants in phytostabilization of Zn, while, Euphorbia macroclada was the most suitable plant for phytostabilization of Cu and Fe, and also Stipa barbata and Chondrila juncea had the highest potential for phytostabilization of Mn (Lorestani et al. 2011). Around the Sarcheshmeh Cu mine, it was reported that Urtica urens has the greatest potential for Sr absorption (Shahraki et al. 2008). Subsequent research by Ghaderian & Ghotbi Ravandi (2012) revealed that two specific plant species, namely E. hirsutum and P. fugax can be tentatively regarded as hyperaccumulators of Cu in the Sarcheshmeh Cu mining area. In a more recent study, Z. fabago, A. leucoclada, C. dactylon, and T. ramosissima, were found to possess high tolerance and high potential for adsorbing various PTEs at Sarcheshmeh Cu mine tailings (Tabasi et al. 2018). Sonchus oleraceus grown nearby the Cheshmeh-Konan Cu deposit (NW Iran) was evaluated by Samadi et al. (2019) for PTE absorption. This study revealed that S. oleraceus has a high potential to absorb Sc, Sn, Sr, Mo, and Cd. Three prevalent plants in Sorkheh and Mazraeh mines, including Cirsium vulgare, Stachys inflata, and Alhaji maurorum, were evaluated by Hoseinpour et al. (2020) for their potential to absorb metals from polluted soils. They reported that S. inflata and A. maurorum have significant potential for the accumulation of Sc, Mo, and Cd from impacted soils in the Sorkheh region. The implemented phytoremediation using various phytoagents show that phytoextraction is the most common method employed with only one study employing phytostabilization which was successful for Cu. Thus, it will be important to also identify plant excluders that can stabilize the most polluting PTEs; Pb and Mo.

Similarly, phytoextraction of Cu has been successful in various Cu mines in other parts of the world. Different plant species have successfully absorbed Cu. Albeit the success with Cu extraction, there is little information on the phytoremediation of other prevalent PTEs in Cu mines. Cultivation of Brassica juncea L resulted in several positive effects in impacted soil from the Cu mine in Touro, Galicia, Spain. These effects included an increase in content of C and total N in soil, a reduction in extreme soil acidity, and a decrease in the pseudototal concentration of Cu (Rodríguez-Vila et al. 2014). In order to identify ideal hyperaccumulators, Wang et al. (2019) investigated dominant plants species in the Machangqing Cu mine area (Yunnan Province, China). They identified that P. yunnanensis and P. massoniana showed substantial Cd uptake as well as an extreme capacity to transfer PTEs from roots to leaves. Such characteristics make these plants valuable for phytoremediation in mining areas for mitigating environmental pollution. In cases where soil pollution is not too high, Ptychostomum capillare was able to absorb Cu, according to research done on biomonitoring of PTE contamination in a former Cu mine in Central Spain (Elvira et al. 2020). Petrović et al. (2021) conducted a study in Bor, Serbia, an area known for Cu mining and discovered that sun spurge (Euphorbia helioscopia L.) had the highest concentration of each metal compared to other plants, particularly Cu. This suggests that sun spurge has more effective mechanisms for extracting, transferring, and accumulating metals than common nettle (Urtica dioica L.).

Conclusion and future perspectives

Cu mining produces large amounts of waste, such as tailings and acid outflows, which pose threats to human health as well as potentially serious and long-lasting environmental effects. Scholars from all over the world, including those in different parts of Iran, have examined soil metal pollution resulting from Cu mining in great detail. This study offers the first thorough evaluation of the amounts of pollutants known to be PTEs in the soils of Iranian Cu mining sites. Since Sarcheshmeh Copper Mine is the largest and most significant Cu mine in Iran, the majority of research that have been undertaken have focused on it. Environmental impact assessment studies have focused on the soils surrounding the most significant Cu mines in Iran, while several other Cu mines have not received the same attention. Various elements were analyzed in the soils surrounding copper mining areas, with Cu, Cd, Pb, and Zn being the most frequently measured metals. The results show that PTEs discharged during mining operations have seriously contaminated the soils in these areas, with Cu, Pb, and Mo showing up as the most common contaminants. These substances have the potential to negatively impact soil fertility and quality, which could have an impact on animal and human health by way of the food chain. In Iranian Cu mining sites, phytoremediation—especially phytoextraction—has been the only used remediation technique, indicating a sustainable solution to dealing with PTE contamination. Identifying the most efficient plant species for phytoremediation in these areas primarily involved studying native plant species growing in polluted soils. To address issues with phytoextraction, like PTE transmission to the food chain and biomass disposal, more research must be done on phytostabilization strategies, especially for Pb and Mo. In order to improve remediation efforts and environmental management techniques, this review emphasizes the significance of thorough PTE monitoring throughout all Iranian copper mines and additional research on native plant species that successfully stabilize PTEs in copper mining sites. Thus, for future studies related to soil pollution by PTEs in Cu mine sites and surrounding environments, the following recommendations should be considered:

  • More investigations of PTEs are needed in the different Cu mines in Iran with suitable phytoremediation strategies for most common PTEs.

  • In Iran only the phytoremediation strategy has been used in Cu mining areas. Therefore, future studies should focus on implementing developed and environmentally friendly techniques to enhance soil health in Cu mines. Some potential approaches to consider include the utilization of biochars and nano materials.

  • Different routes of PTEs emission in soil from Cu mining sites should be extensively investigated for future studies.

  • Assessment and monitoring of the risk element’s contamination of the air-borne dust derived from copper mining should be considered for future studies.