Soil contamination around porphyry copper mines: an example from a semi-arid climate.

Extraction and processing of disseminated metalliferous ores, porphyry copper in particular, results in significant tonnages of waste and can cause severe disturbances and contamination in natural ecosystems. This is particularly important in semi-arid climates where natural soils are often deprived of organic matter and nutrients. This study was conducted on seven sites around Sungun Copper Mine, northwest Iran. Soil texture, EC, pH, and concentrations of nutrients, organic matter, along with 16 metal and metalloids were measured in 94 soil samples. Results showed a gradient of contamination from low contamination in natural hillsides to high contamination in mine waste depositories, Waste Dump and Oxide Dump, alongside Pakhir and Sungun Rivers. Nutrient deficiency occurred in disturbed sites. The main contaminant point sources were Waste Dump, mine pit drainage, and Oxide Dump. The results of Non-metric multidimensional scaling ordination showed elevated Cd, Zn, Fe, Cu, Pb, As, Mo, Mn, Co, S concentrations, high EC, and higher sand percentage in the sites affected by mine waste and acid mine drainage. Geo-Accumulation and Potential Ecological Risk Indices indicated that Pakhir riverside, Sungun riverside, and Oxide Dump have severe to moderate levels of environmental risks. Positive correlations between certain metal elements suggest common sources and similar reaction pathways, which may contribute to their similar geochemical behaviour in transport, deposition, and interdependence. Overall, the deficiency of organic matter and nutrients along with the soil sandy texture in contaminated sites of Sungun Copper Mine are the main limiting factors in managing metal mobility and soil remediation.

Mechanisms of Uptake and Translocation of Thallium in Brassica Vegetables: An X-ray Fluorescence Microspectroscopic Investigation.

Most nonoccupational human exposure to thallium (Tl) occurs via consumption of contaminated food crops. Brassica cultivars are common crops that can accumulate more than 500 µg Tl g-1. Knowledge of Tl uptake and translocation mechanisms in Brassica cultivars is fundamental to developing methods to inhibit Tl uptake or conversely for potential use in phytoremediation of polluted soils. Brassica cultivars (25 in total) were subjected to Tl dosing to screen for Tl accumulation. Seven high Tl-accumulating varieties were selected for follow-up Tl dosing experiments. The highest Tl accumulating Brassica cultivars were analyzed by synchrotron-based micro-X-ray fluorescence to investigate the Tl distribution and synchrotron-based X-ray absorption near-edge structure spectroscopy (XANES) to unravel Tl chemical speciation. The cultivars exhibited different Tl tolerance and accumulation patterns with some reaching up to 8300 µg Tl g-1. The translocation factors for all the cultivars were >1 with Brassica oleracea var. acephala (kale) having the highest translocation factor of 167. In this cultivar, Tl is preferentially localized in the venules toward the apex and along the foliar margins and in minute hot spots in the leaf blade. This study revealed through scanning electron microscopy and X-ray fluorescence analysis that highly Tl-enriched crystals occur in the stoma openings of the leaves. The finding is further validated by XANES spectra that show that Tl(I) dominates in the aqueous as well as in the solid form. The high accumulation of Tl in these Brassica crops has important implications for food safety and results of this study help to understand the mechanisms of Tl uptake and translocation in these crops.

Chemical transformations of arsenic in the rhizosphere-root interface of Pityrogramma calomelanos and Pteris vittata.

Pityrogramma calomelanos and Pteris vittata are cosmopolitan fern species that are the strongest known arsenic (As) hyperaccumulators, with potential to be used in the remediation of arsenic-contaminated mine tailings. However, it is currently unknown what chemical processes lead to uptake of As in the roots. This information is critical to identify As-contaminated soils that can be phytoremediated, or to improve the phytoremediation process. Therefore, this study identified the in situ distribution of As in the root interface leading to uptake in P. calomelanos and P. vittata, using a combination of synchrotron micro-X-ray fluorescence spectroscopy and X-ray absorption near-edge structure imaging to reveal chemical transformations of arsenic in the rhizosphere-root interface of these ferns. The dominant form of As in soils was As(V), even in As(III)-dosed soils, and the major form in P. calomelanos roots was As(III), while it was As(V) in P. vittata roots. Arsenic was cycled from roots growing in As-rich soil to roots growing in control soil. This study combined novel analytical approaches to elucidate the As cycling in the rhizosphere and roots enabling insights for further application in phytotechnologies to remediated As-polluted soils.

Element distribution in electrochemically treated mine wastewater for efficient resource recovery and water treatment: A pilot study.

The feasibility of recovering major and critical elements from acid mine drainage using a pilot-scale electrochemical reactor (ECR) was investigated by assessing elements concentration and species distribution in the liquid and solid phase (sludge) in multistage tests. These were carried out at different electrical currents (18-22 amps) and thus, pH (8-12). The results showed that major metals Al, Cu and Fe were removed from the liquid phase at pH 5.9 while remaining the majority of Zn (57.2 ppm). On the other hand, at pH 7, the effluent was mainly composed of Mn (7.3 ppm). These results were confirmed by the simulation results using the PHREEQC model, which also identified the main chemical species in solution and the precipitates formed after the treatment (oxyhydroxides/sulfates/oxides). The ECR treatment led to sludges with targeted critical elements, some up to 20 times (Co, Be and Sb) higher than their earth's crustal abundance. At pH 10, rare earth elements in the sludge targeted Ce, followed by Nd and La. This study is one of the few studies carrying a detailed analysis of the behavioural distribution pattern of these elements at each pH, which opens the door for the potential of recovering these elements.

Accelerating bioleaching of tungsten mining wastes using indigenous acidophilic bacteria.

The growing amount of W mining waste produced globally is of concern for its proven hazard to the environment and to human health. While uncontrolled biooxidation can result in environmental harm, bioleaching, where pregnant leach solutions are controlled, has been widely used in the mining industry for valuable metals recovery, often from low-grade materials. This bioleaching study was developed to evaluate whether the biogeochemical reprocessing of W tailings could be employed for the decontamination of W-bearing mine waste, combined with valuable metals recovery, i.e., turning a waste into a resource. Using an in-vitro laboratory model, the susceptibility of wolframite [(Fe,Mn)WO4] to acid dissolution during the concomitant oxidation of co-localized sulfidic minerals represented the basic strategy for enhanced W recovery. Encouragingly, geochemistry and synchrotron-based X-ray absorption near edge structure of weathered W tailings demonstrated that early-stage wolframite dissolution occurred. However, W dissolution was limited by the formation of secondary W minerals; weathering produced two secondary W minerals i.e., gallium-rich tungstate and minor sanmartinite [(Zn,Fe)WO4]. The dissolution and re-precipitation of W minerals may provide a strategy for W waste reprocessing if the two processes can be separated by initially putting W into solution, and allowing for its extraction from tailings, followed by its' recovery by secondary W mineral formation.

Microbially influenced tungsten mobilization and formation of secondary minerals in wolframite tailings.

Wolframite [(Fe,Mn)WO4] tailings represent a hazardous waste that can pose a threat to the environment, humans, animals and plants. The present study aims to conduct a high-resolution depth profile characterization of wolframite tailings from Wolfram Camp, North Queensland, Australia, to understand the biogeochemical influences on W mobilization. Several indigenous Fe- and S-oxidizing bacteria (e.g., Streptococcus pneumoniae and Thiomonas delicata) in wolframite tailings were found highly associated with W, As, and rare earth elements. Biooxidation of metal sulfides, i.e., pyrite, molybdenite and bismuthinite, produced sulfuric acid, which accelerated the weathering of wolframite, mobilizing tungstate (WO42-). Using synchrotron-based X-ray fluorescence microscopy (XFM) and W L-edge X-ray absorption near-edge spectroscopy (µ-XANES) analysis, wolframite was initially transformed into Na- and Bi- tungstate as well as tungstic acid (partial weathering) followed by the formation of Ga- and Zn- tungstate after extensive weathering, i.e., the wolframite had disappeared. While W (VI) was the major W species in wolframite tailings, minor W(0) and W(II), and trace W(IV) were also detected. The major contaminant in the Wolfram Camp tailings was As. Though wolframite tailings are hazardous waste, the toxicity of W was unclear. Tungsten waste still has industrial value; apart from using them as substitution material for cement and glass production, there is interest in reprocessing W waste for valuable metal recovery. If the environmental benefits are taken into consideration, i.e., preventing the release of toxic metals into surrounding waterways, reprocessing may be economic.

Sulfur and oxygen isotope constraints on sulfate sources and neutral rock drainage-related processes at a South African colliery.

Understanding the fundamental controls that govern the generation of mine drainage is essential for waste management strategies. Combining the isotopic composition of water (H and O) and dissolved sulfate (S and O) with hydrogeochemical measurements of surface and groundwater, microbial analysis, composition of sediments and precipitates, and geochemical modeling results in this study we discussed the processes that control mine water chemistry and identified the potential source(s) and possible mechanisms governing sulfate formation and transformation around a South African colliery. Compared to various South African water standards, water samples collected from the surroundings of a coal waste disposal facility had elevated Fe2+ (0.9 to 56.9 mg L-1), Ca (33.0 to 527.0 mg L-1), Mg (6.2 to 457.0 mg L-1), Mn (0.1 to 8.6 mg L-1) and SO4 (19.7 to 3440.8 mg L-1) and circumneutral pH. The pH conditions are mainly controlled by the release of H+ from pyrite oxidation and the subsequent dissolution of carbonates and aluminosilicate minerals. The phases predicted to precipitate by equilibrium calculation were green rusts, ferrihydrite, gypsum, ±epsomite. Low concentrations of deleterious metals in solution are due to their low abundance in the local host rocks, and their attenuation through adsorption onto secondary Fe precipitates and co-precipitation at the elevated pH values. The δ34S values of sulfate are enriched (-6.5 ‰ to +5.6 ‰) compared to that of pyrite sampled from the mine (mean -22.5 ‰) and overlap with that of the organic sulfur of coal from the region (-2.5 to +4.9 ‰). The presence of both sulfur reducing and oxidizing bacteria were detected in the collected sediment samples. Combined, the data are consistent with the dissolved sulfate in the sampled waters from the colliery being derived primarily from pyrite probably with the subordinate contribution of organic sulfur, followed by its partial removal through precipitation and microbially-induced reduction.

Comprehensive insights in thallium ecophysiology in the hyperaccumulator Biscutella laevigata.

Biscutella laevigata is the strongest known thallium (Tl) hyperaccumulator plant species. However, little is known about the ecophysiological processes leading to root uptake and translocation of Tl in this species, and the interactions between Tl and its chemical analogue potassium (K). Biscutella laevigata was subjected to hydroponics experimentation in which it was exposed to Tl and K, and it was investigated in a rhizobox experiment. Laboratory-based micro-X-ray fluorescence spectroscopy (µ-XRF) was used to reveal the Tl distribution in the roots and leaves, while synchrotron-based µ-XRF was utilised to reveal elemental distribution in the seed. The results show that in the seed Tl was mainly localised in the endosperm and cotyledons. In mature plants, Tl was highest in the intermediate leaves (16,100 µg g-1), while it was one order of magnitude lower in the stem and roots. Potassium did not inhibit or enhance Tl uptake in B.laevigata. At the organ level, Tl was localised in the blade and margins of the leaves. Roots foraged for Tl and cycled Tl across roots growing in the control soils. Biscutella laevigata has ostensibly evolved specialised mechanisms to tolerate high Tl concentrations in its shoots. The lack of interactions and competition between Tl and K suggests that it is unlikely that Tl is taken up via K channels, but high affinity Tl transporters remain to be identified in this species. Thallium is not only highly toxic but also a valuable metal and Tl phytoextraction using B. laevigata should be explored.

Metal and metalloid accumulation in native plants around a copper mine site: implications for phytostabilization.

Mining activities can result in a pollution legacy of metal and metalloid containing soils and wastes. In this study concentrations of the metals and metalloids Al, As, Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Zn, and the non-metals (P, S) were measured in the shoots of 35 different plant species spontaneously growing at four contaminated sites around the Sungun Copper Mine in East Azerbaijan (Iran) in order to evaluate their potential in phytoremediation of this area. The results show that metal and metalloid accumulation differed between the different species. None of the plant species exceeded the relevant trace element hyperaccumulation thresholds. Plant accumulation of Al was found to be relatively high in Achillea vermicularis (Asteraceae, with up to 5,280 µg g-1) and in Trifolium fragiferum (Fabaceae, with up to 4,895 µg g-1). Papaver dubium (Papaveraceae) had relatively high foliar Cu concentrations (with up to 294 µg g-1) while growing in the waste Rrock dump. Teucrium polium (Lamiaceae) had the highest concentrations of Pb (with up to 62 µg g-1). Most of the native species can be classed as metal-tolerant "excluder"-type species, and may, therefore, be suitable for phytostabilization of the mining wastes around the Sungun Copper Mine.

Plants growing on metalliferous soils are threatened by mining and mineral extraction. Identifying the flora in metal-contaminated soils and mineral wastes is of great importance for biodiversity conservation and for their use in future reclamation programs. This study adds valuable information on the potential of native plants for use in the phytoremediation of copper mines in Iran, as well as in other parts of the world with a similar geology and climate.

Geochemical stability of potentially toxic elements in porphyry copper-mine tailings from Chile as linked to ecological and human health risks assessment.

The geochemical stability, in terms of potential mobility and derived ecological and human health risks of potentially toxic elements (PTEs), of diverse fresh and old porphyry Cu-mine tailings from Chile was assessed through an integrated methodology comprising four interrelated investigation levels: (1) chemical composition and contamination degree of tailings by PTEs, (2) mineralogical characterization by X-ray diffraction and quantitative automated mineralogy analysis by scanning electron microscopy (QEMSCAN®), (3) partitioning and potential mobility of PTEs within the tailings by a sequential extraction procedure (SEP) and leaching tests, and (4) ecological risk assessment (ERA) and human health risk assessment (HHRA). According to pollution indices, Cu, As, Pb, and Mo are most concerning PTEs present in the tailings. SEP shows that major portion of the PTEs are strongly fixed as residual fraction, and thus are poorly mobilizable and bioavailable. Among the PTEs, Cu, As, and Mo were identified as the PTEs most prone to mobilization. Leaching tests show that a low fraction of PTEs is water-leachable. Seawater enhances Mn and As leaching, while process water increases the leaching of Cu, Mn, and Mo. Phosphate particularly promotes leaching of As and Cu, whereas it does not mobilize or even immobilize Pb in the tailings. ERA suggests that mainly old tailings pose a very high potential risk for ecological receptors (PERI = 663-3356), mostly due to Cu and As. HHRA indicates that the old tailings pose higher potential non-carcinogenic and carcinogenic health risks, while the risk decreases in the order ingestion > dermal > inhalation for both children and adults. Non carcinogenic and carcinogenic HHRA points to As as the main PTE of concern via ingestion pathway in the tailings. Overall, the results revealed that particularly old tailings, containing mixed slag-tailings, pose considerable risks to the environment and human health due to potential PTEs mobilization and this aspect requires scrutiny for proper tailings management, including storage, sealing, and eventual tailings reprocessing and/or site rehabilitation after closure.

Root responses to localised soil arsenic enrichment in the fern Pityrogramma calomelanos var. austroamericana grown in rhizoboxes.

The terrestrial fern Pityrogramma calomelanos, a cosmopolitan tropical species, is one of the strongest known arsenic (As) hyperaccumulator plants. This study aimed to determine whether P. calomelanos preferentially forages for arsenite (As3+) or arsenate (As5+) in As-contaminated soils, and whether a positive root response to As enhances accumulation in P. calomelanos. Therefore, an experiment using rhizoboxes divided in two halves were constructed with a control soil (C) and As3+ or As5+ dosed soil at either 50 and 100 µg g-1 As. Micro-X-ray Fluorescence elemental mapping (µXRF) was employed to analyze the distribution of As in roots and fronds, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) was used to determine As distribution in the reproductive tissues of P. calomelanos. The results showed that Pityrogramma roots do not specifically forage for As-contaminated soil; the area based on pixel counts was similar across all the treatments with no statistical differences. However, frond biomass was slightly higher in the treatments C ǀ As3+ and C ǀ As5+, and the highest accumulation of As in fronds was in the As5+ ǀ As3+ (100 µg g-1) treatment, with 3418 and 2370 µg g-1 in old and young fronds respectively. Arsenic cycling across the roots was observed by the µXRF mapping; in C ǀ As5+ (100) the As was higher and evenly distributed in both sections, whilst in C ǀ As3+ (50), the As was higher in the As3+ side. The µXRF mapping showed a broader As distribution in older fronds, where As was highest in the rachis and extended into the pinnule through the midrib. Pityrogramma calomelanos does not specifically root forage for As-enriched zones in the soil and grows healthily without signs of toxicity at lower (50 µg g-1) and higher (100 µg g-1) concentrations of As3+ and As5+ in the soil.

Staged electrochemical treatment guided by modelling allows for targeted recovery of metals and rare earth elements from acid mine drainage.

Acid mine drainage (AMD) is a challenge for current and legacy mining operations worldwide given its potential to severely harm ecosystems and communities if inadequately managed. Treatment costs for AMD are amongst the highest in the industrial wastewater treatment sector, with limited sustainable options available to date. This work demonstrates a novel chemical-free approach to tackle AMD, whereby staged electrochemical neutralisation is employed to treat AMD and concomitantly recover metals as precipitates. This approach was guided by physico-chemical modelling and tested on real AMD from two different legacy mine sites in Australia, and compared against conventional chemical-dosing-based techniques using hydrated lime (Ca(OH)2) and sodium hydroxide (NaOH). The electrochemical treatment demonstrated the same capacity than Ca(OH)2 to neutralise AMD and remove sulfates, and both were significantly better than NaOH. However, the electrochemical approach produced less voluminous and more easily settleable sludge than Ca(OH)2. Moreover, the staged treatment approach demonstrated the potential to produce metal-rich powdered solids with a targeted composition, including rare earth elements and yttrium (REY). REY were recovered in concentrations up to 0.1% of the total solids composition, illustrating a new avenue for AMD remediation coupled with the recovery of critical metals.

Indicators of metal pollution in prospective mining regions: a case study from Philippines.

Understanding the baseline geochemistry of stream waters in a prospective mining area is the key to responsible life-of-mine planning and the protection of local rivers. This can be sometimes challenging due to the presence of abandoned mines, small scale mining, and geogenic sources of metals in the same area, particularly under a tropical humid climates with rivers carrying intermittently high solid loads. This study is focused on the Pula Bato, Danlag, Altayan, and Taplan Rivers in such a climatic setting in Philippines. The rivers are located in the vicinity of the Tampakan ore deposit. It was observed that elemental concentrations in water samples from Pula Bato were generally higher when compared to concentrations from Danlag, Taplan, and Altayan samples. In particular, SO42-, TDS, Al, Cu, Fe, Mn, Ni, and Zn present considerably higher concentrations in the water samples from Pula Bato. It was shown that water quality of Pula Bato is influenced by the natural weathering of sulphide minerals which is further enhanced by the small scale mining activities and old underground workings. The mining effects on the water of Pula Bato River were not apparent in the water of the Altayan due to the possible dilution of the uncontaminated water from Danlag River and sorption processes occurring during the course of contaminants transport. The geochemical indicators and water distinctions can be used in future for catchment-scale geochemical balance modelling.

Removal of dissolved chromium from synthetic mine effluent: A mesocosm experiment.

Dispersion of hexavalent chromium (Cr(VI)) in streams around nickel laterite mines, which are mostly located in the tropics, may pose serious risks for the environment and human health. In an earlier study, a local natural wetland effectively removed Cr from a nickel mine environment in Indonesia. In order to understand the processes and conditions that would facilitate the establishment of operational constructed wetlands that would remove Cr from mine water discharge, we used two native macrophyte species from the same wetland, Lepironia articulata and Machaerina rubiginosa, in a series of mesocosm experiments to follow the distribution of Cr species in water, substrate and plants. A 1 m3 mesocosm was charged with a sand/compost mixture to a depth of 0.5 m, filled to within 0.1 m from the top by water with Cr concentrations of about 1.0 mg L-1, similar to mine discharge water, and plants were introduced to part of the substrate surface. Stage 1 of the experiment supplied and removed fresh water continuously by surface flow, maintaining a residence time of 12 h. In stages, the water was recirculated (Stage 2), more plants were added (Stage 3) and outflow conditions were changed from totally surface to partially from beneath the substrate (Stage 4). All stages lowered Cr concentrations at the surface water outflow, but Cr concentrations were lower again close to the sediment/water interface. Due to the reduction of Cr(VI), the Cr concentrations in substrate pore water were higher near the surface compared to those at depth, and the pore water concentrations of Cr(VI) and total Cr were higher in the vegetated area compared to the non-vegetated area. Higher plant density and mixed species composition of the macrophytes did not increase the efficiency of Cr(VI) removal from the system. The hybrid system, comprising surface and below-substrate outflow (Stage 4), removed hexavalent chromium at a much higher rate than surface outflow only.

Environmental geochemistry of the abandoned Mamut Copper Mine (Sabah) Malaysia.

The Mamut Copper Mine (MCM) located in Sabah (Malaysia) on Borneo Island was the only Cu-Au mine that operated in the country. During its operation (1975-1999), the mine produced 2.47 Mt of concentrate containing approximately 600,000 t of Cu, 45 t of Au and 294 t of Ag, and generated about 250 Mt of overburden and waste rocks and over 150 Mt of tailings, which were deposited at the 397 ha Lohan tailings storage facility, 15.8 km from the mine and 980 m lower in altitude. The MCM site presents challenges for environmental rehabilitation due to the presence of large volumes of sulphidic minerals wastes, the very high rainfall and the large volume of polluted mine pit water. This indicates that rehabilitation and treatment is costly, as for example, exceedingly large quantities of lime are needed for neutralisation of the acidic mine pit discharge. The MCM site has several unusual geochemical features on account of the concomitant occurrence of acid-forming sulphide porphyry rocks and alkaline serpentinite minerals, and unique biological features because of the very high plant diversity in its immediate surroundings. The site hence provides a valuable opportunity for researching natural acid neutralisation processes and mine rehabilitation in tropical areas. Today, the MCM site is surrounded by protected nature reserves (Kinabalu Park, a World Heritage Site, and Bukit Hampuan, a Class I Forest Reserve), and the environmental legacy prevents de-gazetting and inclusion in these protected area in the foreseeable future. This article presents a preliminary geochemical investigation of waste rocks, sediments, secondary precipitates, surface water chemistry and foliar elemental uptake in ferns, and discusses these results in light of their environmental significance for rehabilitation.

Understanding the salinity issue of coal mine spoils in the context of salt cycle.

Coal mine spoils (CMSs), the solid wastes originated from the rock formations and soil cover overlying or interbedded with coal seams, are a worldwide environmental management challenge. Previous studies have shown that salinity is of most concern among the CMSs' environmental impacts, especially in Australia. With increasing concerns from both the governments and communities, there is a real need for the coal mining industry to understand the source, dynamics and management options of CMS salinity. We reviewed the general properties of CMSs from coal mine sites worldwide and the current understanding of the CMS salinity, which are in a limited number of available published reports. Properties (e.g., pH, electrical conductivity and hydraulic conductivity) of studied CMSs varied largely due to its complex lithological origination. A conceptual model was proposed to illustrate the origin, dispersion paths and transformations dynamics of salts in spoils, taking the scenario of a coal mine in Australia as an example. The major factors governing the salt dynamics in CMSs are summarized as mineral weatherability and salt leachability of the spoils. Management of CMS salinity is still a vague area awaiting more extensive studies. Three topics related to the management were explored in the review, which are pre-mining planning, spatial variability of spoil properties and remediation including electrokinetics and phytoremediation. Particularly, based on the geological classification of CMSs and the leachate chemistry of spoils of various sources, a clear relationship between salinity and geounits was established. This association has a potential application in pre-mining planning for the management of salinity from coal mine spoils.

Geochemical assessments and classification of coal mine spoils for better understanding of potential salinity issues at closure.

Coal mining wastes in the form of spoils, rejects and tailings deposited on a mine lease can cause various environmental issues including contamination by toxic metals, acid mine drainage and salinity. Dissolution of salt from saline mine spoil, in particular, during rainfall events may result in local or regional dispersion of salts through leaching or in the accumulation of dissolved salts in soil pore water and inhibition of plant growth. The salinity in coal mine environments is from the geogenic salt accumulations and weathering of spoils upon surface exposure. The salts are mainly sulfates and chlorides of calcium, magnesium and sodium. The objective of the research is to investigate and assess the source and mobility of salts and trace elements in various spoil types, thereby predicting the leaching behavior of the salts and trace elements from spoils which have similar geochemical properties. X-ray diffraction analysis, total digestion, sequential extraction and column experiments were conducted to achieve the objectives. Sodium and chloride concentrations best represented salinity of the spoils, which might originate from halite. Electrical conductivity, sodium and chloride concentrations in the leachate decreased sharply with increasing leaching cycles. Leaching of trace elements was not significant in the studied area. Geochemical classification of spoil/waste defined for rehabilitation purposes was useful to predict potential salinity, which corresponded with the classification from cluster analysis based on leaching data of major elements. Certain spoil groups showed high potential salinity by releasing high sodium and chloride concentrations. Therefore, the leaching characteristics of sites having saline susceptible spoils require monitoring, and suitable remediation technologies have to be applied.