Development of orthophosphate and silica treatments for the management of environmental contaminants at Wilkes landfill, East Antarctica

Thesis by publication.Includes bibliographical referencesSection 1. Introduction. Chapter 1. Research introduction -- Section 2. Literature review. Chapter 2. On-site and in situ remediation technologies applicable to metal-contaminated sites in Antarctica and the Arctic ; Chapter 3. On-site and in situ remediation technologies applicable to petroleum hydrocarbon contaminated sites in the Antarctic and Arctic -- Chapter 4. Chemical immobilisation of metals and metalloids by phosphates -- Chapter 5. Immobilisation and encapsulation of contaminants using silica treatments -- Section 3. Research objectives. Chapter 6. Research focus and objectives -- Section 4. Wilkes. Chapter 7. Introduction to Wilkes Station, East Antarctica ; Chapter 8. Managing legacy waste in the presence of cultural heritage at Wilkes Station, East Antarctica ; Chapter 9. Locating an ice-covered Antarctic landfill using ground magnetometry -- Section 5. Laboratory studies. Chapter 10: Immobilisation of metals in contaminated landfill material using orthophosphate and silica amendments : a pilot study ; Chapter 11. Treatment of soil contaminated with low levels of inorganics using orthophosphate and silica at sites with a heterogeneous distribution of contaminants ; Chapter 12. Characterising mineral products which form upon treatment of metals with orthophosphate, silica or coupled orthophosphate-silica treatments at 2 °C ; Chapter 13: Treatment of soil co-contaminated with metals and petroleum hydrocarbons using silica treatments -- Section 6. Synthesis. Chapter 14. Discussion.Wilkes Station is an abandoned research station located on Clark Peninsula, East Antarctica that was constructed by the United States of America during the International Geophysical Year (1957-1958). In 1961, exclusive control of Wilkes Station transferred to the Australian National Antarctic Research Expeditions. Wilkes Station was abandoned by Australia in 1969, but was not completely decommissioned due to logistical constraints. Consequently the majority of buildings, equipment and a landfill remain on-site. Annex III of the Madrid Protocol (1998) establishes the requirement for all past and present work sites in Antarctica to be cleaned up by the generators and users of sites. In response, various remediation technologies are being adapted or developed for use at contaminated sites in Antarctica and are effective, despite the challenges associated with operating in remote, cold regions. Orthophosphate and silica treatments are two technologies that demonstrate significant potential for use at Wilkes Station and other contaminated sites in Antarctica. However, their application in areas of freezing ground remains understudied.This study assessed the performance of orthophosphate, silica and coupled orthophosphate-silica treatments on metal contaminated soil and soil co-contaminated with metals and petroleum hydrocarbons to evaluate their suitability for the management of environmental contaminants at Wilkes Station. The results of four experiments indicate that silica treatments are effective at immobilising Cr, Fe, Ni, Cu, Zn, Cd, Pb, while orthophosphate and coupled-orthophosphate treatments effectively immobilise Fe, Cu, Zn, Cd and Pb, but are ineffective at immobilising Cr and Ni. None of the assessed treatments were effective at immobilising As, and concentrations of P remained above environmentally safe levels in soils where treatments containing orthophosphoric acid or triple superphosphate were applied. The formation of brushite, cattite, hydroxylapatite, hydroxypyromorphite, sodium aluminosilicates and other calcium bearing minerals following treatment with orthophosphate, silica and coupled orthophosphate-silica provided further evidence of immobilisation.Silica treatments were ineffective at reducing the mobility of petroleum hydrocarbons to environmentally safe levels in soil. Therefore, further research to optimise treatments is required before managing soil co-contaminated with metals and petroleum hydrocarbons using this technique can be considered viable. For effective management of environmental contamination at Wilkes Station, coupling the application of a chemical treatment with a downstream permeable reactive barrier capable of treating petroleum hydrocarbons, As and P contaminated water is recommended. A thorough monitoring program for detection of adverse effects of treatment and the potential for re-solubilisation of metals is also recommended.Mode of access: World wide web1 online resource (xii, 288 pages) colour illustrations, colour map

Immobilization and encapsulation of contaminants using silica treatments : a review

The immobilization and encapsulation of contaminants using silica treatments is an emerging technology for the management of contaminated land. This article reviews the potential of silica treatments for the management of metals, hydrocarbons, and acid mine drainage at contaminated sites; and evaluates the effects of environmental conditions on silica treatment performance. The review demonstrates the potential of silica treatments for managing contaminated land; however, a paucity of research offers only a limited understanding of this technology. Further development of the technology will require additional research evaluating its long-term performance under a range of environmental conditions. Field-based experiments and studies investigating potential adverse effects of silica treatments are also necessary to demonstrate the safety, efficacy, and reliability of silica treatments.19 page(s

Immobilisation of metals in contaminated landfill material using orthophosphate and silica amendments : a pilot study

Immobilization and encapsulation of contaminants using silica and orthophosphate based chemical treatments are emerging technologies applicable to the management of metal contaminated soil. While the efficacy of orthophosphate treatment is well documented, there is a paucity of research on the application of silica or coupled orthophosphate and silica chemical treatments to metal contaminated soil. This paper presents a pilot scale bench study on the use of silica and coupled orthophosphate-silica treatments for the immobilization of metal contaminants in soil material obtained from the Thala Valley landfill, East Antarctica, which in places has petroleum hydrocarbons mixed with metal-contaminated sediment. The performance of the treatments trialed was assessed by the concentrations of copper, zinc, arsenic and lead released using the Toxicity Characteristic Leaching Procedure. The results of this pilot study demonstrate that the orthophosphate-silica treatment was the most effective and reduced leachable copper, zinc and lead by 95%, 96% and 99%, respectively, relative to the experimental controls. Further development of this technique will require additional research evaluating its long-term performance under a range of environmental conditions. Studies investigating potential adverse effects of silica and orthophosphate-silica treatments are also necessary, to demonstrate the environmental risk and efficacy of these remediation technologies.6 page(s

Locating an ice-covered Antarctic landfill using ground magnetometry

At former Antarctic research stations, legacy waste often remains in situ and concealed by ice. Consequently, the location, characteristics and potential environmental impact associated with legacy waste remains poorly documented. This study applies ground magnetometry to map the spatial extent of the landfill at the abandoned Wilkes Station. Magnetic anomalies indicate that the landfill extends north-west to south-east and is close to, and perhaps prograding into, the ocean. The landfill is characterized by large magnetic variations of > 1500 nT with asymmetrical magnetic anomalies which suggest variable orientations of material and random dumping. Magnetic susceptibilities > 0.02SI units beyond the landfill area reveal elevated magnetic properties of the basement geology. However, a contrast in anomaly shape reliably distinguishes large anomalies generated by landfill material. Surface and subsurface melt streams (observed at the shoreline) flowing from the survey area suggest elevated potential for metal contamination of the nearshore and marine environment. The survey demonstrates a cost-effective and non-invasive method for gathering information to guide the clean up of landfills beneath ice.8 page(s

Managing legacy waste in the presence of cultural heritage at Wilkes Station, East Antarctica

The Antarctic Treaty has been the principal governing force in Antarctica since 1961. The Protocol on Environmental Protection to the Antarctic Treaty (Madrid Protocol) requires that all past and present work and waste-disposal sites are cleaned up unless doing so would cause greater environmental damage or the site is considered to be a monument of significant historical importance. Despite this requirement, legacy waste issues remain unresolved in parts of Antarctica. Clean-up operations in Antarctica are complicated by a combination of restricted access, extreme weather, financial limitations and logistical constraints. Further complications arise at sites such as Wilkes Station, where the requirement for clean-up coexists with the desire to preserve potentially valuable heritage items. Several buildings and artefacts with potential heritage value remain at Wilkes Station. However, Wilkes Station is not officially designated as a historic site or monument under the Antarctic Treaty, nor is it a national or world heritage place under Australian domestic legislation. Consequently the buildings and relics at Wilkes Station are afforded little protection under the existing relevant domestic and international legislative frameworks. This paper uses Wilkes Station as a case study of the complexities associated with conducting clean-up operations at contaminated sites with informal heritage value in Antarctica. The legislative and environmental considerations surrounding clean-up operations at Wilkes Station are also investigated. Furthermore, we argue the importance of a multi-disciplinary approach to operations which facilitate the clean-up of legacy waste and preservation of the potential heritage values at Wilkes. Finally, we recognise that the complexities discussed in this paper have wider applicability and we investigate the relevance of these issues to other Antarctic contaminated sites with formal or informal heritage value.9 page(s

Environmental lead exposure risks associated with children's outdoor playgrounds

This study examines exposure risks associated with lead smelter emissions at children's public playgrounds in Port Pirie, South Australia. Lead and other metal values were measured in air, soil, surface dust and on pre- and post-play hand wipes. Playgrounds closest to the smelter were significantly more lead contaminated compared to those further away (t(27.545) = 3.76; p =.001). Port Pirie post-play hand wipes contained significantly higher lead loadings (maximum hand lead value of 49,432 μg/m²) than pre-play hand wipes (t(27) = 3.57, p =.001). A 1% increase in air lead (μg/m³) was related to a 0.713% increase in lead dust on play surfaces (95% CI, 0.253-1.174), and a 0.612% increase in post-play wipe lead (95% CI, 0.257-0.970). Contaminated dust from smelter emissions is determined as the source and cause of childhood lead poisoning at a rate of approximately one child every third day.8 page(s

Chemical immobilization of metals and metalloids by phosphates

Remediation of metal contaminated media using orthophosphate fixation forms insoluble and non-bioavailable salts from metal and phosphate sources. The main focus has been on fixation of Pb, where the formation of pyromorphite, the most insoluble lead phosphate, has shown the great potential of this remediation technique. Other metals (Ba, Cd, Co, Cu, Eu, Ni, U, Zn) also have potential for effective fixation by orthophosphate. We review the applicability of the treatment across wider environmental conditions, particularly in surface soil, its use with elements other than Pb, product stability and efficiency with mixed contaminants.16 page(s

On-site and in situ remediation technologies applicable to metal-contaminated sites in Antarctica and the Arctic: a review

Effective management of contaminated land requires a sound understanding of site geology, chemistry and biology. This is particularly the case for Antarctica and the Arctic, which function using different legislative frame- works to those of industrialized, temperate environments and are logistically challenging environments to operate in. This paper reviews seven remediation technologies currently used, or demonstrating potential for on-site or in situ use at metal-contaminated sites in polar environments, namely permeable reactive barriers (PRB), chemical fixation, bioremediation, phytoremediation, electrokinetic separation, land capping, and pump and treat systems. The technologies reviewed are discussed in terms of their advantages, limitations and overall potential for the management of metal-contaminated sites in Antarctica and the Arctic. This review demonstrates that several of the reviewed technologies show potential for on-site or in situ usage in Antarctica and the Arctic. Of the reviewed technologies, chemical fixation and PRB are particularly promising technologies for metal-contaminated sites in polar environments. However, further research and relevant field trials are required before these technologies can be considered proven techniques.Keywords: Polar; heavy metals; remediation; contaminants; in situ(Published: 31 December 2013)Citation: Polar Research 2014, 33, 21522, http://dx.doi.org/10.3402/polar.v33.2152

On-site and in situ remediation technologies applicable to metal-contaminated sites in Antarctica and the Arctic: a review

Effective management of contaminated land requires a sound understanding of site geology, chemistry and biology. This is particularly the case for Antarctica and the Arctic, which function using different legislative frameworks to those of industrialized, temperate environments and are logistically challenging environments to operate in. This paper reviews seven remediation technologies currently used, or demonstrating potential for on-site or in situ use at metal-contaminated sites in polar environments, namely permeable reactive barriers (PRB), chemical fixation, bioremediation, phytoremediation, electrokinetic separation, land capping, and pump and treat systems. The technologies reviewed are discussed in terms of their advantages, limitations and overall potential for the management of metal-contaminated sites in Antarctica and the Arctic. This review demonstrates that several of the reviewed technologies show potential for on-site or in situ usage in Antarctica and the Arctic. Of the reviewed technologies, chemical fixation and PRB are particularly promising technologies for metal-contaminated sites in polar environments. However, further research and relevant field trials are required before these technologies can be considered proven techniques