This study investigated an uncapped tailings storage facility in a semi-arid subtropical climate, with the aim of understanding the hydro-geochemical processes controlling the seepage water quality and the dispersion/attenuation of metals and metalloids within the tailings and through a constructed wetland. While direct re-vegetation helped to stabilize the surface of tailings, development of an oxidation front in the tailings resulted in high sulphate and arsenic concentrations in the seepage. The findings of this study will assist maximizing the efficiency of any future passive treatment system on site and provide useful information for similar tailings closure strategies elsewhere.

Brine, produced as a by-product of oil extraction, when contained in evaporation ponds can cause soil salinization in the vicinity of these ponds. Native halophytes may assist revegetation and rehabilitation of these salt-affected soils. This study was conducted to investigate the revegetation and rehabilitation potential of brine-affected land using native halophytes (Tecticornia pergranulata (J.M.Black) K.A.Sheph. & Paul G.Wilson, Sclerolaena longicuspis (F.Muell.) A.J.Scott and Frankenia serpyllifolia Lindl). Soil samples from adjacent bare and vegetated areas of brine-affected land were compared to assess the physico-chemical properties associated with the vegetation cover. The salt contents of the halophytes, plant bioaccumulation, bioconcentration, and translocation factors were measured to evaluate remediation capacity of the species. We hypothesized that the halophytes reduce the ions' concentrations and thus soil salinity and sodicity. The examined halophytes were associated with a reduction in salinity and sodicity by an average of 38.5% and 33% in the top 10cm of the soil, respectively. T.pergranulata had the highest shoot Na+ content (98g/kg dry wt), bioaccumulation (14.21), and translocation (23.09) factors for Na+ that indicated the higher remediation potential of this species. Despite the high remediation potential of the examined species, halophytes are not able to reduce the salt content of the landscape to create conditions for the growth of glycophytes. However, the salt-affected land can be revegetated by halophytes, and halophytes probably provide a stable vegetation cover for the landscape in ecological succession. An improvement in soil physical properties is required for revegetation success.

Kinabalu Park is the world’s most species-rich hotspot with over 5000 plant species recorded for an area 1200 km2. The aim of this study was to characterise the vegetation on ultramafic edaphic ‘islands’ in relation to soil chemistry and elevation.

Background and Aims Globally, zinc deficiency is one of the most important nutritional factors limiting crop yield and quality. Despite widespread use of foliar-applied zinc fertilizers, much remains unknown regarding the movement of zinc from the foliar surface into the vascular structure for translocation into other tissues and the key factors affecting this diffusion.Methods Using synchrotron-based X-ray fluorescence microscopy (A mu-XRF), absorption of foliar-applied zinc nitrate or zinc hydroxide nitrate was examined in fresh leaves of tomato (Solanum lycopersicum) and citrus (Citrus reticulatus).Key Results The foliar absorption of zinc increased concentrations in the underlying tissues by up to 600-fold in tomato but only up to 5-fold in citrus. The magnitude of this absorption was influenced by the form of zinc applied, the zinc status of the treated leaf and the leaf surface to which it was applied (abaxial or adaxial). Once the zinc had moved through the leaf surface it appeared to bind strongly, with limited further redistribution. Regardless of this, in these underlying tissues zinc moved into the lower-order veins, with concentrations 2- to 10-fold higher than in the adjacent tissues. However, even once in higher-order veins, the movement of zinc was still comparatively limited, with concentrations decreasing to levels similar to the background within 1-10 mm.Conclusions The results advance our understanding of the factors that influence the efficacy of foliar zinc fertilizers and demonstrate the merits of an innovative methodology for studying foliar zinc translocation mechanisms.

Phytomining technology employs hyperaccumulator plants to take up metal in harvestable plant biomass. Harvesting, drying and incineration of the biomass generates a high-grade bio-ore. We propose that "agromining" (a variant of phytomining) could provide local communities with an alternative type of agriculture on degraded lands; farming not for food crops, but for metals such as nickel (Ni). However, two decades after its inception and numerous successful experiments, commercial phytomining has not yet become a reality. To build the case for the minerals industry, a large-scale demonstration is needed to identify operational risks and provide "real-life" evidence for profitability.

At the invitation of the editors to write an opinion piece, I drafted this to hopefully spark a conversation about the role of the industry in innovation and leading practice development, particularly in relation to land rehabilitation. Having been involved in land rehabilitation as a student, educator, researcher, practitioner and thinker over the last 20 years, my sense is there is a great opportunity for the minerals industry to rediscover its leadership role – which is linked to its social license to operate.

Zinc (Zn) deficiency in soils and plants is a global micronutrient deficiency problem in many cropping regions. Both soil and foliar application of Zn fertilizers have been commonly used to correct Zn deficiency and/or enhance Zn nutrition in crops. However, increasing foliar application of Zn fertilizers has been used to precisely deliver Zn when peak Zn demand could not meet by root Zn uptake at the late vegetative and early reproductive stages, where soil and climatic conditions inhibit adequate Zn uptake through roots. The present review has discussed key processes of foliar penetration of nutrient solutes and critical factors affecting the penetration rate of nutrient ions through the cuticular surfaces, including environmental factors, physiological status of leaves and plants, and physical and chemical properties of fertilizer chemicals used. In particular, the effects of leaf surface characteristics and chemical forms of foliar fertilizers on foliar nutrient uptake have been discussed in detail, with the aim to justify the potential of the newly developed nanocrystals of Zn compounds. Properties of different foliar Zn fertilizers have been compared and major shortcomings with traditional Zn foliar fertilizers have been identified, in relation to the justification to develop a new generation of foliar Zn technology.

This study depicts broad-scale revegetation patterns following sand mining on North Stradbroke Island, south-eastern Queensland, Australia.

Steep terrain, intense rainfall, and seismic activity precluded use of conventional tailings storage facilities at the PT Freeport Indonesia (PTFI) copper–gold mine, in Papua, Indonesia. A controlled river tailings system was adopted as the only feasible way to manage the tailings. The tailings are transported to an engineered 230 km2 deposition area, which is bounded by levees on the east and west sides and is open on the south side to allow transport water and surges of rainfall to exit the area. We evaluated the performance of the ore-fed blending strategy for managing potential acid rock drainage formation of the tailings. Long-term leaching column tests and monitoring of deposited tailings provided insight on the reactivity, leaching behaviours, and neutralizing potential of the samples, and the ratio of acid neutralizing capacity (ANC): maximum potential acidity (MPA) that would ensure that the deposited tailings remain non-acid forming. We concluded that an ANC/MPA ratio >1.5 provides an adequate factor of safety to prevent acid generation and ensure long-term geochemical stability of the deposited tailings.

Revegetation of mine tailings (fine-grained waste material) starts with the reconstruction of root zones, consisting of a rhizosphere horizon (mostly topsoil and/or amended tailings) and the support horizon beneath (i.e. equivalent to subsoil mostly tailings), which must be physically and hydro-geochemically stable. This review aims to discuss key processes involved in the development of functional root zones within the context of direct revegetation of tailings and introduces a conceptual process of rehabilitating structure and function in the root zones based on a state transition model.Field studies on the revegetation of tailings (from processing base metal ore and bauxite residues) are reviewed. Particular focus is given to tailings properties that limit remediation effectiveness. Aspects of root zone reconstruction and vegetation responses are also discussed.When reconstructing a root zone system, it is critical to restore physical structure and hydraulic functions across the whole root zone system. Only effective and holistically restored systems can control hydro-geochemical mobility of acutely and chronically toxic factors from the underlying horizon and maintain hydro-geochemical stability in the rhizosphere. Thereafter, soil biological capacity and ecological linkages (i.e. carbon and nutrient cycling) may be rehabilitated to integrate the root zones with revegetated plant communities into sustainable plant ecosystems. A conceptual framework of system transitions between the critical states of root zone development has been proposed. This will illustrate the rehabilitation process in root zone reconstruction and development for direct revegetation with sustainable plant communities. Sustainable phytostabilization of tailings requires the systematic consideration of hydro-geochemical interactions between the rhizosphere and the underlying supporting horizon. It further requires effective remediation strategies to develop hydro-geochemically stable and biologically functional root zones, which can facilitate the recovery of the microbial community and ecological linkages with revegetated plant communities.

Ant assemblages, used widely as bioindicators of land management practices, were sampled in rehabilitated pastures and surrounding habitats at Norwich Park Coal Mine in central Queensland, Australia. As the end-use goal of a number of rehabilitated mine sites in the region is sustainable pasture-land, the aim of this study was to investigate the influence of varying grazing histories on ant fauna, to provide further understanding on the function of rehabilitated agroecosystems and multi-trophic interactions. Examination of seven study sites revealed three distinct ant assemblages, broadly reflecting mining and grazing history. Rehabilitated pastures where grazing had ceased 2 years prior to ant sampling contained low species richness with a basic ant composition, regardless of stocking rate, and was similar to ungrazed rehabilitated pasture. The rehabilitated pasture with continual low intensity grazing showed ant compositional similarities' to the neighboring unmined pasture, although assemblage descriptors were intermediate between unmined and rehabilitated sites. Buffel grass (Pennisetum ciliare, basionym Cenchrus ciliaris) and other stoloniferous or rhizomatous grasses were the principal influence on ant assemblages, with grazing reducing the ground dominance of such grasses and providing a more favorable habitat for a wider range of ant species. (C) 2012 Elsevier B.V. All rights reserved.

This study investigates change detection in the vegetation cover of a closed gold mine to assess whether the rehabilitated vegetation responds in a similar manner to the surrounding environment. Rehabilitation took place in seven rehabilitation areas within the mine site. SPOT scenes covering the site were acquired at six time periods from September 2004 to September 2005, and annually in the dry season from 2004 to 2010, except for 2008. Normalized difference vegetation index, soil-adjusted vegetation index and transformed soil-adjusted vegetation index were tested to estimate the percentage vegetation cover (PVC) using a linear regression model. The results showed higher PVC during wet season and lower PVC during the dry season in the native vegetation surrounding the mine site. However, temporal and spatial patterns of PVC in rehabilitated and native areas were similar only in the TD40ha rehabilitation area, one of the seven rehabilitation areas. This area was the first to be rehabilitated and had the most intensive rehabilitation effort using tube stock planting in March 1998. The seasonal variability showed a high correlation with an r2 value of 0.77 in TD40ha rehabilitation area in tailings dam, which was similar to the native area with an r2 value of 0.82. The findings of this study suggest that it is important for monitoring programs to take into account seasonal variation and environmental covariates, such as rainfall in order to successfully assess patterns in vegetation condition over time.

This paper examines the minerals industry's response to sustainable development in the area of waste disposal and argues that leadership and guidance are still needed to forge collective agreement on norms and standards of practise. To encourage further debate, the paper develops a set of sustainable development principles for the disposal of mining and mineral processing wastes, and discusses the implications for current and future practise. In practise, the principles can guide waste disposal decisions through the consideration of what risk and magnitude, in any given local context, a particular management solution poses to their application. The sustainability challenge in the management of tailings and waste rock is to dispose of material, such that it is inert or, if not, stable and contained, to minimise water and energy inputs and the surface footprint of wastes and to move toward finding alternate uses. Future trends in mining and processing may compound the challenges of waste management, as lower ore grades increase the ratio of waste produced for a given unit of resource, and emphasise the urgency and need for the industry to adopt new approaches. New technologies and innovations, such as thickened tailings, dry stacking and paste backfill, have greatly increased the waste disposal methods available to meet the future challenges to sustainable development.

Ant communities at Bayside Mine on North Stradbroke Island were examined as bioindicators of rehabilitation success to provide further information on ecosystem health compared to that which is determined by vegetation monitoring.Three distinct assemblages were collected, with the ant fauna at unmined eucalypt forests characteristic of such habitats, with many arboreal, litter-dwelling and shade-preferring species.The community composition of ants at an unburnt 30-year old rehabilitated forest resembled these unmined reference forests, although abundance, species richness and diversity were intermediate between reference sites and younger rehabilitation areas.An adjacent 30-year old rehabilitated forest exposed to wildfire was dissimilar to all sites, likely due to an incursion of the highly competitive pest ant, Pheidole megacephala.This species has been found in rehabilitation sites on the island previously and is thought to prefer areas with established vegetation where the microclimate at ground level has high humidity and lower temperature.Vegetation data from this study supports this suggestion, with a high understorey foliage projective cover and ground vegetation at this site compared to a paired adjacent unburnt site where the pest ant was absent.Ant communities at four 20-year old rehabilitated sites were similar to each other, regardless of management history, and contained mainly generalist species suggesting they were still recovering from the recent disturbances of management practices.Composition patterns, in relation to disturbance, were similar to previous research conducted on the island.

Rainfall ingress into sulfidic rocks or tailings from metalliferous mining operations can result in acid mine drainage. Waste rock cover systems in semiarid areas are commonly designed to retain all precipitated water within benign material, from where it is removed by evapotranspiration. The long‐term effectiveness of covers is often predicted from models that are based on data obtained from single trial plots assuming that the trials are homogeneous and representative of large areas. Two cover designs were tested in semiarid monsoonal northwest Queensland: (i) 1.5 m of unconsolidated waste rock overlying 0.5 m of consolidated waste rock; and (ii) 2.0 m of unconsolidated benign waste rock. Three identical plots comprised each treatment in which water balance equation parameters were estimated from meteorological measurements and vertical arrays of soil suction and moisture sensors and seepage collection using a 3‐m‐deep lysimeter inserted in the waste rock. In a wet season with 900 mm of precipitation, water movement through the covers was followed through changes in moisture content, suction, and seepage. Greater differences in these parameters occurred within than between cover treatments. Water retention and water movement varied substantially and seepage ranged from 2 to 80% of total rainfall. The internal heterogeneity of hydraulic properties had more effect on cover performance than did the initial cover design. Therefore, it is important to include internal heterogeneity in mine waste cover water balance models to improve their applicability.

Sustainable development practices have become an integral part of most major mining companies’ business activities. However, the history of mining and the negative impacts it has had on the natural and social environment mean future mining activities, rightly or wrongly, will be judged against the legacies of the past and current poor performers. Legacy mine land, defined here as land which has been mined and is now being used for another purpose, or is orphaned, abandoned or derelict and in need of remedial work, is one management challenge that will be judged in the context of sustainable development. Globally, millions of such sites exist. Having criteria against which to measure progress toward or away from sustainable development goals is a key to delivering results. The aim of this research was to develop a sustainability criteria and indicators framework to suit the particular needs of legacy mine land. The resulting framework consists of 14 criteria and 72 indicators.

As a mine is closed, the management process is highly likely to be required to support on-going site management and reporting to stakeholders and regulators, for decades afterwards. It is essential, therefore, to ensure the maintenance of corporate memory by retaining essential site data. This site data will provide the foundation for the research science that may be needed to provide confidence on residual risk to regulators in order to gain relinquishment. Partnerships between tertiary institutions and corporations holding the mine sites provide one mechanism to achieve long-term stewardship of site information essential to meet regulatory requirements and support research to fill gaps in knowledge of site-specific natural systems and rehabilitation performance. A set of management system tools has been developed to manage and utilize the wide range of data, reports and images remaining at a number of closed mines, in partnership with the organizations ultimately responsible for the closed sites. This includes purpose-built software that combines accurate and to-scale three-dimensional photo images and scientific software to hold, display and interpret the wide range of environmental data at each site.

Vegetation can potentially assist in limiting the ingress of water into rock dumps or tailings storage facilities, an attractive potential when the geochemical characteristics of such waste materials indicate that water ingress should be minimal in order to reduce long-term impacts and liabilities. However, the presence and/or necessity for vegetation can present potential conflicts for cover design and management as the cover system objectives are often to minimize the amount of cover material required and to establish a low-cost but effective means of removing water from above the waste to reduce the likelihood of deep drainage. Due to the physical nature and heterogeneity of particle sizes and sorting characteristics of many cover materials used, the distribution patterns of water infiltration into constructed profiles may be very irregular, with penetration to depth (and thus potentially the underlying waste material or impervious capping layer) a high probability in zones of higher hydraulic conductivity. This irregularity of water distribution will also result in heterogeneous patterns of vegetation distribution and growth, especially in low rainfall environments. Although actual evapo-transpiration can account for up to 90% of annual rainfall at some locations, vegetation is unlikely to dry cover material completely or prevent water percolation through the root zone during high intensity precipitation events, especially if vegetation distribution and infiltration patterns are irregular. In humid environments, a seasonal water table is likely to develop, making lateral water discharge from within the cover essential, and the integrity of any impervious capping layer (if present over the waste as a part of the design) capable of preventing penetration by plant roots. In semi-arid environments, a thick cover of benign rock may prevent infiltrating water from ever reaching the impervious capping layer, provided plant roots can penetrate the wetting zone and extract all of the water. Trees have many shallow ephemeral roots and fewer roots that may penetrate more than 20 m but they require permanent water for survival. Grasses on the other hand may have a root biomass that fluctuates more between seasons and their dense root systems may be more effective than those of woody plants in removing water from the surface horizons. Detailed site physical and plant physiological data enable soil and plant water balance and plant growth models to predict temporal variations in vegetation cover, but site heterogeneity requires the use of two- or three-dimensional models. There is also the need to increase the capacity to model and quantify the contribution of vegetation to the hydrological processes occurring in cover systems. This paper reviews the information that provided the background and context for a current major research program involving three Australian universities, Canadian collaborators and nine mining company sponsors. Among other goals, this project seeks to increase the understanding of the role of vegetation in cover performance, and the extent of variation in the function and performance of covers over time due to cover construction design, climate, soil physical and chemical changes, and the likely effects of vegetation changes. All sources of variability must be considered in cover design, and if site and species characteristics are well understood, the extent of variation can be indicated clearly and unreal expectations concerning the role and impact of a vegetative cover can be avoided. The Role of Vegetation in Mine Waste Cover Systems with Particular Reference to D.R. Mulligan et al. Australian Mine Rehabilitation