Casey Station Research Articles

Field trial of ion-exchange resin columns for removal of metal contaminants, Thala Valley Tip, Casey Station, Antarctica

Abstract A field trial for removal of dissolved metal contaminants in water from an abandoned waste disposal site, using ion-exchange columns of an iminodiacetic acid chelating ion-exchange (IDA) resin, was conducted at Casey Station, Antarctica. An on-site monitoring technique, employing 3M Empore chelating disks for preconcentration for analysis by atomic absorption spectrometry (AAS), was also trialled for measurement of dissolved metal concentration in the treated water. The field trial indicated that the ion-exchange columns of Amberlite IRC748 were suitable for the application, with concentrations of contaminant metals in treated waters successfully reduced. The observed order of selectivity for contaminant metals was markedly different to that observed in previous laboratory tests; the presence of organic ligands and colloidal iron in the natural waters on-site interfered with the retention of Cu and Fe, reducing selectivity for these metals. The on-site monitoring technique was considered capable of producing results of sufficient accuracy and reproducibility to identify that the ion-exchange columns were effectively reducing metal contaminant concentrations, and to identify breakthrough of the ion-exchange columns. Concentrations of Cd, Ni and Zn corresponded well with the dissolved metal fraction measured by ICP–MS, although Pb analysis was less precise. However, interference from organic ligands and colloids probably caused underestimation in the measurement of these metals. The on-site monitoring technique was useful for providing rapid feedback during clean-up at this remote site. However, the interferences would require careful evaluation in order to relate the measurements to water quality standards or objectives.

Measurement of moss growth in continental Antarctica

Using steel pins inserted into growing moss colonies near Casey Station, Wilkes Land, continental Antarctica, we have measured the growth rate of three moss species: Bryum pseudotriquetrum and Schistidium antarctici over 20 years and Ceratodon purpureus over 10 years. This has provided the first long-term growth measurements for plants in Antarctica, confirming that moss shoots grow extremely slowly in Antarctica, elongating between 1 and 5 mm per year. Moss growth rates are dependent on availability of water. Antheridia were observed on some stems of B. pseudotriquetrum; no archegonia or sporophytes were observed. Stems bearing antheridia elongated much more slowly than vegetative stems in the same habitat. Two other methods of growth rate measurement were tested, and gave similar rates of elongation over shorter periods of time. However, for long-term measurements, the steel pin measurements proved remarkably reproducible and reliable.

Water treatment to prevent contaminant dispersal during remediation of cold regions contaminated sites

Abstract Water collection and treatment is often required for effective cold regions contaminated site clean-up. Large volumes of meltwater runoff can become contaminated during remediation activities and disperse pollutants into the surrounding environment. Of particular importance for Antarctic contaminated sites is the impact of contaminant metals from polluted sites into nearby marine environments and the sensitivity of these environments. A mobile water treatment system was constructed for deployment to remote cold regions contaminated sites for use during clean-up activities. The water treatment system is designed to remove contaminants associated with particles and colloids via coagulation and settling and dissolved metals via ion exchange. This paper gives an overview of laboratory tests necessary to ensure the safe operation of the water treatment plant during the remediation of an abandoned waste disposal site in the Thala Valley near Casey station Antarctica. The results show that through a detailed understanding of the mechanisms this technology can be used to treat water to meet the required guidelines for sensitive environments.

Removal of Metal Contaminants by Ion‐Exchange Resin Columns, Thala Valley Tip, Casey Station, Antarctica

Salinity and low temperature effects on adsorption of contaminant metals from water using an iminodiacetic acid (IDA) ion‐exchange resin, were investigated under dynamic flow conditions. The order of selectivity of the resin (20°C and 0% seawater) was: Cu2+> Pb2+> Cr3+> Ni2+>Cd2+>Zn2+. Low temperature (4°C) had no significant effect on the selectivity of the contaminant metals and salinity only affected selectivity for Cr3+ and Cu2+. Copper had highest selectivity in all column experiments, except where extensive deprotonation occured. Buffering affected retention of Cr3+; possibly due to precipitation or complexation as a result of increase in pH.

Monitoring the remediation of a near shore waste disposal site in Antarctica using the amphipod Paramoera walkeri and diffusive gradients in thin films (DGTs)

The water quality of a marine embayment (Brown Bay) was monitored during the remediation of an abandoned waste disposal site at Casey Station, East Antarctica, using a combination of biomonitoring and chemical methods. The Antarctic amphipod Paramoera walkeri, in field mesocosms suspended in the water column, was deployed adjacent to the site and at two reference sites for periods of 14 days, repeated three times during the remediation period (December to February). Diffusive gradients in thin film (DGT) samplers were deployed for the same periods to provide estimates of dissolved metals. No difference in mortality of amphipods was observed between Brown Bay and reference sites. There were significant differences, however, in accumulated metal concentrations between amphipods from Brown Bay and reference sites, with greater concentrations of antimony, copper, cadmium, lead, iron and tin at Brown Bay. The melt water/runoff treatment strategy employed for the remediation was successful in preventing acute toxic effects, but water quality was reduced at Brown Bay, where increased metal bioavailability may have been high enough to induce chronic effects in some biota. DGT samplers were less sensitive than amphipods in detecting differences in metal concentrations between sites, indicating that metals bound to suspended particulates were a potentially significant source of contamination.

Baseline metal concentrations in Paramoera walkeri from East Antarctica

Remediation of the Thala Valley waste disposal site near Casey Station, East Antarctica was conducted in the austral summer of 2003/2004. Biomonitoring of the adjacent marine environment was undertaken using the gammaridean amphipod Paramoera walkeri as a sentinel species [Stark, J.S., Johnstone, G.J., Palmer, A.S., Snape, I., Larner, B.L., Riddle, M.J., in press, doi:10.1016/j.marpolbul.2006.05.020. Monitoring the remediation of a near shore waste disposal site in Antarctica using the amphipod Paramoera walkeri and diffusive gradients in thin films (DGTs). Marine Pollution Bulletin and references therein]. Determination of uptake of metals and hypothesis testing for differences that could be attributed to contamination required the establishment of baseline metal concentrations in P. walkeri. Baseline metal concentrations from two reference locations in the Windmill Islands are presented here. P. walkeri was a found to be a sensitive bioaccumulating organism that recorded spatial and temporal variability at the reference sites. Measurement of metals in P. walkeri required the development of a simple digestion procedure that used concentrated nitric acid. For the first time, rare earth metals were determined with additional clean procedures required to measure ultra low concentrations using magnetic sector ICP-MS. Certified and in-house reference materials were employed to ensure method reliability.

Evaluation of geochemical methods for discrimination of metal contamination in Antarctic marine sediments: A case study from Casey Station

Detecting anthropogenic metal contamination in regional surveys can be particularly difficult when there is a lack of pre-disturbance data, especially when trying to differentiate low to moderate levels of contamination from background values. Furthermore, comparisons with other regional studies are confounded by differing analytical methods used and variations in sediment properties such as grainsize. Several types of geochemical technique, including weak acid partial extraction, strong acid extractions and total digestion have been used. Attempts have been made to overcome the influence that grainsize has on chemical concentrations in heterogeneous environments by analysing the fines, typically the mud fraction (<63 μm), in an attempt to improve the detection of anthropogenic contamination. Here we compare a weak acid partial extraction using 1 M HCl and total digestion methods for a regional survey of reference and impacted sites in Antarctica using both whole sediment (<2 mm) and mud (<63 μm) fractions. The 1 M partial extraction on whole sediment (<2 mm) most closely distinguished weakly, or moderately, impacted sites from reference locations. It also identified small scale within-location spatial variation in metal contamination that the total digest did not detect. Compared with total digests or analysis of the <63 μm fraction alone, this method minimised the possibility of a Type II statistical error in the regional survey – that is, failing to identify a site as being contaminated when it has elevated metal concentrations. To allow inter-regional comparison of sediment chemistry data from elsewhere in Antarctica, and also more generally, we recommend a 1 M HCl partial extraction on whole sediment (<2 mm).

Abandoned Antarctic waste disposal sites: Monitoring remediation outcomes and limitations at Casey Station

Abandoned work sites, disposal sites, hazardous waste and untreated fuel spills in Antarctica have recently begun to receive significant attention. A profile of the clean‐up at Casey waste disposal site demonstrates a suite of cultural, social, economic and scientific changes to the way Antarctica and its environmental management are viewed.

Fertilization Stimulates Anaerobic Fuel Degradation of Antarctic Soils by Denitrifying Microorganisms

Human activities in the Antarctic have resulted in hydrocarbon contamination of these fragile polar soils. Bioremediation is one of the options for remediation of these sites. However, little is known about anaerobic hydrocarbon degradation in polar soils and the influence of bioremediation practices on these processes. Using a field trial at Old Casey Station, Antarctica, we assessed the influence of fertilization on the anaerobic degradation of a 20-year old fuel spill. Fertilization increased hydrocarbon degradation in both anaerobic and aerobic soils when compared to controls, but was of most benefit for anaerobic soils where evaporation was negligible. This increased biodegradation in the anaerobic soils corresponded with a shift in the denitrifier community composition and an increased abundance of denitrifiers and benzoyl-CoA reductase. A microcosm study using toluene and hexadecane confirmed the degradative capacity within these soils under anaerobic conditions. It was observed that fertilized anaerobic soil degraded more of this hydrocarbon spike when incubated anaerobically than when incubated aerobically. We conclude that denitrifiers are actively involved in hydrocarbon degradation in Antarctic soils and that fertilization is an effective means of stimulating their activity. Further, when communities stimulated to degrade hydrocarbons under anaerobic conditions are exposed to oxygen, hydrocarbon degradation is suppressed. The commonly accepted belief that remediation of polar soils requires aeration needs to be reevaluated in light of this new data.

In situ lubricant degradation in Antarctic marine sediments. 1. Short‐term changes

A large-scale, in situ experiment was set up near the Bailey Peninsula area (Casey Station, East Antarctica) to monitor the natural attenuation of synthetic lubricants in marine sediments over five years. Here, we report the short-term changes after 5 and 56 weeks. The lubricants tested were an unused and used Mobil lubricant (0W/40; Exxon Mobil, Irving, TX, USA) and a biodegradable alternative (0W/20; Fuchs Lubricants, Harvey, IL, USA). Clean sediment was collected, contaminated with the lubricants, and deployed by divers onto the seabed in a randomized block design. The sampled sediments were analyzed by gas chromatography-flame-ionization detector and gas chromatography-mass spectrometry with selective ion monitoring. The base fluid of all lubricant treatments did not decrease significantly after 56 weeks in situ. Alkanoate esters of 1,1,1-tris(hydroxymethyl)propane in the biodegradable and unused lubricants were degraded extensively in situ; however, these esters constituted only a minor proportion of the lubricant volume. The additives, alkylated naphthalenes and substituted diphenylamines, were fairly resistant to degradation, which is of environmental concern because of their toxicity. The biodegradable lubricant did not break down to recognized biodegradable thresholds and, as such, should not be classified as biodegradable under Antarctic marine conditions. A separate experiment was conducted to determine the influence of sediment preparation and deployment on compound ratios within the lubricants, and we found that preparation and deployment of the contaminated sediments had only a minor effect on compound recovery. Further monitoring of this in situ experiment will provide much needed information about the long-term natural attenuation of lubricants.

Identifying the Characteristics of Strong Southerly Wind Events at Casey Station in East Antarctica Using a Numerical Weather Prediction System

Abstract Casey Station in East Antarctica is not often subject to strong southerly flow off the Antarctic continent but when such events occur, operations at the station are often adversely impacted. Not only are the dynamics of such events poorly understood, but the forecasting of such occurrences is difficult. The following study uses model output from a 12-month experiment using the Antarctic Limited-Area Prediction System (ALAPS) to advance the understanding of the dynamics of such events and postulates that what are often described as katabatic wind events are more likely to be synoptic in scale, with mid- and upper-level tropospheric dynamics forcing the surface layer flow. Strong surface layer flows that have a katabatic signature commonly develop on the steep Antarctic escarpment but rarely extend out over the coast in the Casey area, most probably as a result of cold air damming. However, the development of a strong south-southwesterly jet over Casey provides a mechanism whereby the katabatic can move out off the coast.

Investigation of evaporation and biodegradation of fuel spills in Antarctica: II—Extent of natural attenuation at Casey Station

In many temperate regions, fuel and oil spills are sometimes managed simply by allowing natural degradation to occur, while monitoring soils and groundwater to ensure that there is no off-site migration or on-site impact. To critically assess whether this approach is suitable for coastal Antarctic sites, we investigated the extent of evaporation and biodegradation at three old fuel spills at Casey Station. Where the contaminants migrated across frozen ground, probably beneath snow, approximately half the fuel evaporated in the first few months prior to infiltration at the beginning of summer. Once in the ground, however, evaporation rates were negligible. In contrast, minor spills from fuel drums buried in an abandoned waste disposal site did not evaporate to the same extent. Biodegradation within all three spill sites is generally very minor. We conclude that natural attenuation is not a suitable management strategy for fuel-contaminated soils in Antarctic coastal regions.

Location and DGGE methodology can influence interpretation of field experimental studies on the response to hydrocarbons by Antarctic benthic microbial community

A field experiment investigating the effect of oil contamination on benthic microbial communities was conducted near Casey Station, East Antarctica. Defaunated sediment was treated with a mixture of Special Antarctic Blend diesel and lubricating oil and deployed in three different bays for eleven weeks. A molecular fingerprinting technique, denaturing gradient gel electrophoresis (DGGE), was used to investigate the microbial community structure. The variation between replicate samples within treatment groups indicates that the benthic microbial populations are very diverse and evenly distributed. Comparisons to determine the significance of both deployment location and hydrocarbon treatment showed that the greatest effect was from a combination of location and treatment. Detailed analysis suggests that subtle differences may be obscured by variability introduced by PCR and gel stages in DGGE, undermining this experimental approach. It is concluded that both location and hydrocarbon contamination influenced the development of the microbial communities but that the effect of hydrocarbon treatment varied with location. This has important implications for the design of future experiments on the effect of hydrocarbons on benthic communities, especially if it is intended to generalize the conclusions drawn from site specific studies.

Benthic diatom communities as indicators of anthropogenic metal contamination at Casey Station, Antarctica

Prior to environmental legislation in the 1980s, anthropogenic waste in Antarctica was often deposited into landfill sites or into the sea. This resulted in metal contamination in terrestrial and near-shore marine environments. In this study, we assess the feasibility of using both past and present diatom assemblages to reconstruct and monitor past and future metal contamination. Our dataset included the analyses of both surface sediment samples and sediment cores from a contaminated site near Casey Station, Antarctica. Redundancy analyses indicated a strong relationship between metal concentrations and the composition of diatom communities. Within the surface sediment samples, tin and lead individually explained 43% of the variation observed in the diatom data; copper and iron explained 42% of this variation. In the sediment cores, tin and lead individually explained 53% of the variation in diatom community composition. In the same samples copper explained 47% of this variation, with iron explaining 46% of the observed variation. Once one metal had been selected, incorporating further metal data into the analyses added little extra information. Modern analog technique (MAT) analyses showed a strong correlation between actual and predicted values within one dataset (R2: Cu 0.75; Pb 0.86; Sn 0.89; p<0.05 for each). MAT reconstructions of metal concentrations closely followed measured concentrations, with both high and low concentrations recorded. MAT analyses performed favorably when compared to predictive techniques based on multivariate linear regression and multilayer perceptron neural networks. This study demonstrates that the composition of benthic diatom communities is a good indicator of anthropogenic metal contamination, and may be useful in monitoring the success of environmental remediation strategies in Antarctica and elsewhere.

Variations of snow petrel breeding success in relation to sea-ice extent: detecting local response to large-scale processes?

Demographic parameters were estimated for snow petrels Pagodroma nivea nesting at the study colony of Reeve Hill near Casey station, Antarctica between 1984 and 2003. Average breeding success for the colony varied from 18.2% to 76.5%. Breeding effort, hatching and fledging success were subject to a high interannual variability. We examined the influence of regional sea-ice extent on the breeding performance of snow petrels at Reeve Hill. Fewer birds were breeding when sea-ice had been extensive during April–May. Overall breeding success and fledging success were improved during years with extensive sea-ice cover in winter. Successful breeding effort and breeding success were depressed when there was extensive sea-ice cover during January–February. Sea surface temperatures also correlated to snow petrel breeding performance parameters. Previous work showed that large-scale climatic events (ENSO, Antarctic circumpolar wave) and the related sea-ice cover around the Antarctic might affect the lower trophic levels of the marine environment and consequently food availability for snow petrels. A comparison with the long-term study conducted at Ile des Petrels (Terre Adelie) suggests that despite similarities in the underlying biological processes that control snow petrel breeding performance, the nature of the correlation of large-scale environmental factors with breeding performance differs substantially between the two colonies, probably because of the confounding effects of other environmental factors acting at a local scale (local weather, nest quality), which also affect bird body condition.

A comparison of the short term effects of diesel fuel and lubricant oils on Antarctic benthic microbial communities

The effects of diesel fuel and three lubricating oils on microbial communities in marine sediment were investigated in a field experiment at Casey Station, Antarctica. Sediment from a pristine site in Antarctica was treated with either Special Antarctic Blend (SAB) diesel, a synthetic lubricant (Mobil 0W-40), the same lubricant after use in a vehicle or an equivalent unused biodegradable lubricant (Titan GT1). The sediment was re-deployed in trays on the seabed for 5 weeks during the austral summer. The microbial community structure in the sediment upon collection, deployment and retrieval was investigated using denaturing gradient gel electrophoresis (DGGE), most probable number (MPN) counts and direct microscopic counting. It was found that only minor changes occurred in the microbial communities due to the experimental protocol. After 5 weeks however, there were significant differences between the communities in the SAB and clean and used lubricant (Mobil 0W-40) as compared to the control treatment. There was no significant difference between the control and biodegradable oil (Titan GT1) treatment. These results indicate that SAB and synthetic lubricants have a measurable effect on sediment microbial communities in the short-term. The biodegradable oil did not produce such an effect and we conclude that the use of such an oil could reduce the risks associated with oil spills in the Antarctic environment.

Alien fly populations established at two Antarctic research stations

The populations of two non-native Dipterans have been established at two Antarctic research stations since at least 1998. Both belong to Sciaridae (“black fungus midge”), and have been determined to the genus Lycoriella. At Rothera Research Station, Antarctic Peninsula, flies are present in the station alcohol bond store, while at Casey Station, on the coast of continental Antarctica, a second Lycoriella sp. is found breeding in the station sewage facilities. Neither species is thought capable of surviving outside the protected environment of the research station buildings, but their establishment highlights the need for strict quarantine controls in order for National Operators in the Antarctic to conform to the Environmental Protocol of the Antarctic Treaty and prevent the introduction of alien species into Antarctica. Protocols for fly eradication are currently being implemented.

Removal of Metal Contaminants from Saline Waters at Low Temperature by an Iminodiacetic Acid Ion‐Exchange Resin, Thala Valley Tip, Casey Station, Antarctica

Effects of salinity and low temperature on the removal of dissolved contaminant metals from water by an iminodiacetic acid (IDA) ion‐exchange resin, Amberlite IRC748, were investigated under batch equilibrium conditions. As expected for ions retained by chelation, the efficiency of the resin was reduced with low temperature. The efficiency of the resin increased with salinity: increasing salinity (from 0% seawater) reduces protonation of the resin, lowering solution pH into the optimum pH range for the retention of contaminant metal ions. Selectivities of the divalent matrix cations, Ca2+ and Mg2+, were decreased with increasing salinity: this is attributed to a shift to an ion‐exchange retention mechanism for these ions, which is favoured at lower solution pH. At low salinity, the selectivity for Ca2+ and Mg2+ was decreased at low temperature, however at higher salinities, selectivity was unaffected by low temperature. This is consistent with the proposal of a shift from a chelation to an ion‐exchange mechanism for these ions.

Bioturbation behaviour of the spatangoid urchin Abatus ingens in Antarctic marine sediments

A series of in situ and aquarium experiments were conducted in the vicinity of the Bailey Peninsula area (Casey Station, East Antarctica) to investigate the bioturbation behaviour of the Antarctic spatangoid urchin Abatus ingens (Koehler 1928). Rates of sediment transport by A. ingens were estimated from measurements of locomotion rates, sediment reworking depth and feeding rates. A. ingens bioturbates and feeds on the surface sediment (top 1 to 2 cm) by pushing diatom communities and sediment ahead and to the side of its track, thus increasing vertical and horizontal sediment transport. Over a 24 h period in situ, A. ingens spends prolonged periods of time stationary (16.7 h) and only short periods of time in locomotion (7.3 h). In the aquarium, however, A. ingens was observed to spend half of the time moving and the other half stationary. Locomotion rate measured in the aquarium was faster (1.95 cm h -1 [1.20 SD]) than in situ (0.30 cm h -1 [0.27 SD]). In addition, A. ingens moves significantly faster during light hours than periods of darkness in situ. An ingestion rate of 0.02 to 0.06 g h -1 of dry sediment was measured for A. ingens, with a gut sediment passage time of 72 to 97 h. A. ingens reworks 2.76 cm 3 h -1 (2.52 SD) in situ; however, this calculation (based on forward movement only) may be an underestimate because A. ingens still reworks the sediment (via rocking and rotating on the spot) when it is not moving forwards. It is concluded that A. ingens is a significant contributor to the reworking of sediments in the Antarctic benthic environment.

Constraints on spatial variability in soft-sediment communities affected by contamination from an Antarctic waste disposal site

A small-scale (<500 m length) transect-based survey was conducted in December 1998 to examine the spatial distribution of soft-sediment communities and of concentrations of heavy metals and hydrocarbons in sediments in Brown Bay, adjacent to an abandoned waste dump, at Casey Station, Antarctica. Samples were taken along three transects at increasing distances (nine stations) from the shore-line waste dump. A gradient of contamination was detected, but concentrations of contaminants were very variable with “hotspots” or high levels of contaminants at some stations. Multivariate analysis revealed that the distribution of soft-sediment communities was distinctly different between the inner, middle and outer stations. Abundances of most taxa were very variable with few patterns apparent, but some fauna displayed an abundance gradient from the inner to the outer part of the bay. Many taxa had maximum abundances at outer stations and minimum at inner stations. Multivariate correlations between environmental variables and soft-sediment communities indicated that combinations of some metals (Cd, Cu, Sn, Pb) and grain size (mainly finer fractions, fine sands and coarse silts) were the variables that best “matched” the community patterns within Brown Bay. This study indicated that there were significant correlations between the presence of contaminants and the distribution and composition of soft-sediment communities over very small spatial scales.