The Impacts of Burn Severity and Frequency on Erosion in Western Arnhem Land, Australia.

Wildfires are pivotal to the functioning of many ecosystems globally, including the magnitude of surface erosion rates. This study aims to investigate the relationships between surface erosion rates and wildfire intensity in the tropical north savanna of Australia. The occurrence of fires in western Arnhem Land, Northern Territory, Australia was determined with remotely sensed digital datasets as well as analogue erosion measurement methods.

Sediment spiking and equilibration procedures to achieve partitioning of uranium similar to contamination in tropical wetlands near a mine site.

The derivation of sediment quality guideline values (SQGVs) presents significant challenges. Arguably the most important challenge is to conduct toxicity tests using contaminated sediments with physico-chemistry that represents real-world scenarios. We used a novel metal spiking method for an experiment that ultimately aims to derive a uranium SQGV.

A comparative bio-oxidative leaching study of synthetic U-bearing minerals: Implications for mobility and retention.

In this study, the effects of bio-oxidative leaching on several synthetic uranium minerals - Uraninite [UO], Pitchblende [UO], Coffinite [USiO], Brannerite [UTiO] and Betafite [(U,Ca)(Ti,Nb,Ta)O]) compared to chemical leaching in the presence of pyrite was investigated. In all cases, bio-oxidative leaching was faster and increased overall %U extraction compared to chemical leaching. The results indicated that the bio-oxidative leachability of the uranium minerals was in the order: pitchblende≈ uraninite > coffinite>> brannerite > betafite.

Radon-222 diffusion length and exhalation characteristics of uraniferous waste rock and application to mine site remediation in the Australian wet-dry tropics.

The diffusion length of Rn in uraniferous waste rock was determined through a novel experiment. Large PVC columns were filled to different depths in the range from 0.5 m to 3.

PUBLIC EXPOSURE TO EXTERNAL GAMMA RADIATION ON A MINE LANDFORM COVERED BY LOW URANIUM GRADE WASTE ROCK.

Public exposure to external gamma radiation on the waste-rock-covered-8.5-km2-planned final landform from rehabilitation of the Ranger uranium mine was assessed. The average above-background dose rate from external gamma radiation on the planned final landform was determined to be 6.

Whole organism concentration ratios of radionuclides and metals in terrestrial vertebrates of an Australian tropical savanna environment.

Preliminary values of whole organism concentration ratio (CR) were derived for terrestrial vertebrates of an Australian tropical savanna environment. Wildlife groups included bird, bat, ground-dwelling mammal and reptile. Sample data for some of the wildlife groups (bird and bat in particular) were limited.

Modelling the dispersion of radionuclides in dust from a landform covered by low uranium grade waste rock.

The dispersion of radionuclides in dust and inhalation dose rates to the public from the planned remediation of the Ranger uranium mine in the wet-dry tropics of Australia was modelled using RESRAD-OFFSITE. Dust inhalation dose rates were predicted to be highest on the remediated site and decrease with an approximate inverse square to inverse cubic dependence with distance from the site. The annual dose above natural background to a hypothetical individual permanently occupying the remediated site (representing the worst case scenario for radionuclide in dust exposure) was estimated to be 5.

Whole organism concentration ratios in freshwater wildlife from an Australian tropical U mining environment and the derivation of a water radiological quality guideline value.

More than 10,000 whole organism concentration ratio (CR) values for freshwater wildlife were derived from radionuclide and stable element data representing an Australian tropical U mining environment. The CR values were summarised into five wildlife groups (bird, fish, mollusc, reptile and vascular plant). The summarised CR values represented 77 organism-element combinations.

Modelling the dispersion of radon-222 from a landform covered by low uranium grade waste rock.

The dispersion of Rn from the planned remediation of the Ranger U mine in the wet-dry tropics of Northern Australia was modelled. Dry and wet season contour maps of Rn dose normalised to Ra activity concentration in the proposed waste rock substrate on the remediated landform were developed. Three example exposure scenarios were assessed based on an anticipated waste rock Ra activity concentration of 800 Bq kg.

Whole organism to tissue concentration ratios derived from an Australian tropical dataset.

Whole organism to tissue concentration ratios (CR) were derived for six wildlife groups (freshwater birds, freshwater bivalves, freshwater fishes, freshwater reptiles, freshwater vascular plants and terrestrial mammals). The wildlife groups and data represented species common to tropical northern Australia. Values of CR were derived for between 6 and 34 elements, depending upon wildlife group.

Natural radionuclides and stable elements in weaver ants (Oecophylla smaragdina) from tropical northern Australia.

Natural radionuclides and stable elements were measured in weaver ants, leaves and soils collected from three sites in tropical northern Australia. Radionuclide concentration ratios for ants relative to soil were derived from the measurements and used to refine the current environmental radiological assessment for remediation of Ranger uranium mine. Use of site-specific concentration ratios for weaver ants gave a more conservative estimate of environmental exposure to the arthropod wildlife group than use of default concentration ratios in the ERICA Tool.

Water hardness determines Ra uptake in the tropical freshwater mussel.

Chemical data for freshwater mussels (Velesunio spp.) and water from 15 sampling sites in the Alligator Rivers Region and Rum Jungle uranium provinces in tropical Northern Australia were analysed to develop a predictive model of radium-226 (Ra) bioaccumulation for variable water calcium (Ca) and magnesium (Mg) concentrations. Application of the model as a Ra screening approach for freshwater mussels in tropical waterbodies potentially impacted by operational or remediated uranium mine sites is discussed in relation to Mudginberri Billabong, located approximately 12 km downstream of Ranger uranium mine in the Alligator Rivers Region.

Estimating doses from Aboriginal bush foods post-remediation of a uranium mine.

This paper presents a calculator to facilitate assessments of ingestion doses from Aboriginal bush foods. The calculator combines information on traditional diet and land use with radionuclide concentration ratios and ingestion dose coefficients to estimate doses. The calculator was applied to the planned remediation of Ranger uranium mine to derive a set of scaling factors between radionuclide activity concentrations in environmental media and ingestion dose from bush foods.

A tool for calculating concentration ratios from large environmental datasets.

This paper presents a tool for calculating concentration ratios from a large and structured environmental dataset of radionuclide activity and metal concentrations. The tool has been developed in MS Excel™ and includes a simple user interface for setting up queries. The tool is capable of matching environmental media samples to biota samples based on user-defined spatial and temporal criteria to derive a representative estimate of the environmental exposure conditions of an organism and its accumulation.

A database of radionuclide activity and metal concentrations for the Alligator Rivers Region uranium province.

This paper presents a database of radionuclide activity and metal concentrations for the Alligator Rivers Region (ARR) uranium province in the Australian wet-dry tropics. The database contains 5060 sample records and 57,473 concentration values. The data are for animal, plant, soil, sediment and water samples collected by the Environmental Research Institute of the Supervising Scientist (ERISS) as part of its statutory role to undertake research and monitoring into the impacts of uranium mining on the environment of the ARR.

A soil radiological quality guideline value for wildlife-based protection in uranium mine rehabilitation.

A soil guideline value for radiological protection of the environment was determined for the impending rehabilitation of Ranger uranium mine in the wet-dry tropics of northern Australia. The guideline value was 1000 Bq kg(-1) of (226)Ra in the proposed waste rock substrate of the rehabilitated landform and corresponded to an above-baseline dose rate of 100 μGy h(-1) to the most highly exposed individuals of the limiting organism. The limiting organism was reptile based on an assessment using site-specific concentration ratio data.

Influence of group II metals on Radium-226 concentration ratios in the native green plum (Buchanania obovata) from the Alligator Rivers Region, Northern Territory, Australia.

In this study, uptake of Ra from soil, and the influence of group II metals on Ra uptake, into the stones and edible flesh of the fruit of the wild green plum, Buchanania obovata, was investigated. Selective extraction of the exchangeable fraction of the soil samples was undertaken but was not shown to more reliably predict Ra uptake than total soil Ra activity concentration. Comparison of the group II metal to Ca ratios (i.

Soil invertebrate community change over fuel-contaminated sites on a subantarctic island: An ecological field-based line of evidence for site risk assessment.

A number of fuel spills, of both recent and historic origins, have occurred on World Heritage-listed subantarctic Macquarie Island. Sites contaminated by mainly diesel fuels are undergoing remediation by the Australian Antarctic Division. The risks posed by these sites are being managed using a "weight of evidence" approach, for which this study provides a preliminary line of evidence for the ecological assessment component of this site management decision framework.

Long-term temporal variability of the radon-222 exhalation flux from a landform covered by low uranium grade waste rock.

Radon-222 exhalation flux densities from two different substrates of several metres thickness, waste rock and waste rock mixed with approximately 30% lateritic material, were measured over a period of five years in the wet-dry tropics of Northern Australia. Fourteen measurement campaigns using activated charcoal canisters (n > 1000) covered both dry and wet seasons and showed differences in seasonal and long term trends of the (222)Rn exhalation flux densities normalised to the (226)Ra activity concentrations of the substrate. Dry season (222)Rn exhalation was generally higher for the mixed substrate, due to the larger fraction of fines.

Ra and Ra measurement on a BaSO co-precipitation source.

One of the most commonly-used methods for determination of Ra, particularly in water samples, utilises co-precipitation of Ra with BaSO, followed by microfiltration to produce a source for alpha counting. This paper describes two extensions to BaSO co-precipitation methods which enable determination of Ra using the same source. The adaptations presented here do not introduce any contaminants that will affect the separation of radium or alpha counting for Ra, and can be used for re-analysis of already existing sources prepared by BaSO co-precipitation.

Variability of atmospheric krypton-85 activity concentrations observed close to the ITCZ in the southern hemisphere.

Krypton-85 activity concentrations in surface air have been measured at Darwin, which is located in northern Australia and is influenced by seasonal monsoonal activity. Measurements between August 2007 and May 2010 covered three wet seasons. The mean activity concentration of krypton-85 measured during this period was 1.

Hadley cell influence on (7)Be activity concentrations at Australian mainland IMS radionuclide particulate stations.

Beryllium-7 ((7)Be) daily data from the four International Monitoring System (IMS) radionuclide particulate stations on mainland Australia are analysed over the period 2001 to 2011. The analysis indicates that levels of (7)Be in surface air at the stations follow annual cycles, with yearly peak activity concentrations occurring later at stations further south. The yearly peak migrates north-south at a rate of approximately 4.

Determining a pre-mining radiological baseline from historic airborne gamma surveys: a case study.

Knowing the baseline level of radioactivity in areas naturally enriched in radionuclides is important in the uranium mining context to assess radiation doses to humans and the environment both during and after mining. This information is particularly useful in rehabilitation planning and developing closure criteria for uranium mines as only radiation doses additional to the natural background are usually considered 'controllable' for radiation protection purposes. In this case study we have tested whether the method of contemporary groundtruthing of a historic airborne gamma survey could be used to determine the pre-mining radiological conditions at the Ranger mine in northern Australia.

Radium concentration factors in passionfruit (Passiflora foetida) from the Alligator Rivers Region, Northern Territory, Australia.

In this study, uptake of Ra from soil into the edible fruit of the wild passionfruit species Passiflora foetida was investigated, using selective extraction from the soil samples. A wide range of environmental exposure conditions were represented by the locations that were sampled, including both natural soils, and soils influenced by past and present uranium mining activities. The bioavailable (226)Ra fraction in soils was found to be a better predictor of (226)Ra fruit activity concentrations than the total soil activity concentration, or any of the other fractions studied.