Damian B. Gore

Management and remediation of contaminated sites at Casey Station, Antarctica

The Protocol on Environmental Protection to the Antarctic Treaty requires that past and present work sites be cleaned up unless removal would result in greater adverse environmental impact than leaving the contaminant in its existing location. In the early 1990s Australia began the documentation of contaminated sites associated with its research stations, which resulted in an extensive record of contamination at abandoned stations and waste-disposal sites. Currently the technical capability to remediate these sites does not exist because of environmental challenges that are unique to the cold regions. Investigations indicate that clean-up operations in the past have proceeded without adequate precautions and without effective monitoring. To address these problems, three research priorities have been identified to assist meeting international and national obligations to clean up these sites. They are: understanding contaminant mobilisation processes; development of ecological risk assessment for use in monitoring and setting priorities; and development of clean-up and remediation procedures. This study provides sufficient information to guide the completion of a clean-up at Casey Station and to indicate how other similar sites should be managed. The next stage is to develop the theory into an operational plan to include detailed protocols for clean-up, monitoring, site remediation, and management of the waste stream from site to final repository. To achieve this, the Australian Antarctic Division has established a contaminated sites taskforce to facilitate the transition from research and development of techniques to implementation of suitable clean-up options.

Exposure ages from mountain dipsticks in Mac. Robertson Land, East Antarctica, indicate little change in ice-sheet thickness since the Last Glacial Maximum

Past changes in East Antarctic Ice Sheet (EAIS) volume are poorly known and diffi cult to measure, yet are critical for predicting the response of the ice sheet to modern climate change. In particular, it is important to identify the sources of sea-level rise since the Last Glacial Maximum (LGM), and ascertain the present-day stability of the world’s largest ice sheet. We present altitudinal transects of 10 Be and 26 Al exposure ages across the Framnes Mountains in Mac. Robertson Land that allow the magnitude and timing of EAIS retreat to be quantifi ed. Our data show that the coastal EAIS thinned by at most 350 m in this region during the past 13 k.y. This reduction in ice-sheet volume occurred over a ~5 k.y. period, and the present icesheet profi le was attained ca. 7 ka, in contrast to the West Antarctic Ice Sheet, which continues to retreat today. Combined with regional offshore and terrestrial geologic evidence, our data suggest that the reduction in EAIS volume since the LGM was smaller than that indicated by contemporary ice-sheet models and added little meltwater to the global oceans. Stability of the ice margin since the middle Holocene provides support for the hypothesis that EAIS volume changes are controlled by growth and decay of Northern Hemisphere ice sheets and associated global sea-level changes.

Bunger Hills, East Antarctica: Ice free at the Last Glacial Maximum

Optically stimulated luminescence dating of glaciofluvial and glacial-lake shoreline sediments indicates that the Bunger Hills area, in coastal East Antarctica, was largely ice free by the Last Glacial Maximum (LGM). Deglaciation commenced as early as 30 ka, and the southern hills were completely exposed by 20 ka. The sediments do not record evidence of an LGM readvance. Previous reconstructions of LGM ice limits for the area are incompatible with this new evidence.

The Holocene Diatom Flora of Marine Bays in the Windmill Islands, East Antarctica

Abstract The Holocene diatom flora identified in three sediment cores from marine bays in the Windmill Islands (East Antarctica) is described and depicted for the first time. One hundred and twenty-four diatom taxa could be identified of which eighty-one taxa have a circum-Antarctic distribution. All taxa are listed in a table together with appropriate references and remarks on ecology and biogeography. The most diverse genera are Fragilariopsis, Navicula and Thalassiosira. Some taxa (e.g., Chaetoceros spp., Fragilariopsis curta, F. cylindrus, Navicula glaciei and Synedropsis spp.) have the potential to be used as indicator taxa for the reconstruction of palaeoceanographic conditions in the Windmill Islands.

Palaeoclimatic significance of late Quaternary diatom assemblages from southern Windmill Islands, East Antarctica

Abstract The late Quaternary palaeoenvironmental history of the southern Windmill Islands, East Antarctica, has been reconstructed using diatom assemblages from two long, well-dated sediment cores taken in two marine bays. The diatom assemblage of the lowest sediment layers suggests a warm climate with mostly open water conditions during the late Pleistocene. During the following glacial, the Windmill Islands were covered by grounded ice preventing any in situ bioproductivity. Following deglaciation, a sapropel with a well-preserved diatom assemblage was deposited from ∼10 500 cal yr BP. Between ∼10 500 and ∼4000 cal yr BP, total organic carbon (Corg) and total diatom valve concentrations as well as the diatom species composition suggest relatively cool summer temperatures. Hydrological conditions in coastal bays were characterised by combined winter sea-ice and open water conditions. This extensive period of glacial retreat was followed by the Holocene optimum (∼4000 to ∼1000 cal yr BP), which occurred later in the southern Windmill Islands than in most other Antarctic coastal regions. Diatom assemblages in this period suggest ice-free conditions and meltwater-stratified waters in the marine bays during summer, which is also reflected in high proportions of freshwater diatoms in the sediments. The diatom assemblage in the upper sediments of both cores indicates Neoglacial cooling from ∼1000 cal yr BP, which again led to seasonally persistent sea-ice on the bays. The Holocene optimum and cooling trends in the Windmill Islands did not occur contemporaneously with other Antarctic coastal regions, showing that the here presented record reflects partly local environmental conditions rather than global climatic trends.

Colonization, succession, and extinction of marine floras during a glacial cycle: A case study from the Windmill Islands (east Antarctica) using biomarkers

With the exception of the diatoms, little is known of the extinction, colonization, and succession of marine floras during glacial cycles. Here we study both morphological and biochemical fossils in two sediment cores from the Antarctic to unravel the sequence of events over a single glacial cycle. The cores, from the nearshore continental shelf off the Windmill Islands (66°S, 110°E), east Antarctica, span the period from Marine Isotope Stage 3 or earlier to the present. New high-performance liquid chromatography and mass spectrometry methods were used to study fossil pigments with additional data from siliceous microfossils, lithological analyses, and radiocarbon dates. Results show two response processes. First, there is the large-scale impact of the expanding ice sheet in removing the flora from the inner shelf, primarily through the denial of light, destabilization of the substratum, and elimination of habitats. Second, there are a number of glacial climate interactions that have a surprisingly strong influence on recolonization and succession. These include sea ice extent and the proximity of the ice edge, the annual duration of open water, the stabilization of the substratum first by benthic diatoms and later by macrophyte algae, and relative sea level. A period of warmer climate in the mid-Holocene had a considerable influence on the composition and species diversity of the marine flora. These are the first data on the timing of colonization and succession of marine floras over a glacial cycle based on both morphological and biochemical fossils.

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.

Petroleum hydrocarbons ten years after spillage at a helipad in Bunger Hills, East Antarctica

Surface and subsurface sediments from a helipad in Bunger Hills were collected ten years after accidental contamination with a small quantity (probably < 10 litres) of petroleum products. The contaminants are dominated by Jet A2 synthetic lubricating oil which exhibits no evidence of degradation or environmental mobility. In contrast, Jet A 1 turbine kerosene is less abundant at the surface than at 20 cm depth. There is no evidence for biodegradation of the Jet A 1 in the subsurface sample, suggesting that kerosene is environmentally mobile in the surface sediments.

Soil phosphorus enhancement below stormwater outlets in urban bushland: spatial and temporal changes and the relationship with invasive plants

Invasion by exotic plant species is a significant problem in urban bushland remnants and is often associated with nutrient enrichment of soils. A major source of nutrient enrichment in urban areas is stormwater runoff, which is transferred from impervious surfaces in urban catchments and discharged at outlets on the residential/bushland interface. We measured the spatial extent of soil total phosphorus (P) enhancement below stormwater outlets on Hawkesbury Sandstone-derived soils in northern Sydney and examined whether total P concentration has increased with time since urban development and extended laterally beyond the stormwater flow path. The average area of soil P enhancement below outlets was 0.24 ± 0.05 ha and was widest 30–50 m downslope from the outlet, where it extended an average 40 m across slope. Catchment area was not significantly related to average soil total P concentration. There was a significant decline in total P across slope from the centre of the flow path and a significant positive relationship between soil total P and proportion of exotic plant cover, with soil P accounting for 77.5% of variation. We found evidence for a build-up in soil total P concentration over time within the run-on zone below outlets, with the rate of enhancement being ~68 mg/kg per decade over a 40-year period. Evidence for lateral transfer of soil P out of the run-on area was more equivocal. There was a significant decline in soil total P across slope from the boundary of the run-on zone, with higher concentrations at distances 0.5 m and 1 m from the boundary compared with >1.5 m. However, this could be due to error in locating the boundary between run-on and non run-on areas. There was no significant relationship between soil P in the non run-on zone and age of development, which would be expected if P was being transferred by biological activity beyond the run-on zone over time. It is clear that the primary areas of concern for management must be the run-on areas below outlets.

An analysis of the limnology and sedimentary diatom flora of fourteen lakes and ponds from the Windmill Islands, East Antarctica

The limnology and sedimentary diatom flora of fourteen lakes and ponds from the Windmill Islands, East Antarctica, is presented. Saline lakes, saline ponds and freshwater ponds are represented in this dataset. The Windmill Island lake diatom flora represents an intermediate floral assemblage between that of the freshwater lakes of the Larsemann Hills and the saline lakes of Vestfold Hills, East Antarctica. Variations within this assemblage are related to water chemistry variables in the Windmill Island lakes. In particular, a lakewater salinity/phosphate gradient can explain the variation observed in the sedimentary diatom flora of the lakes and ponds included in this study.