Michael G. Lawrence

Removal of PFOS, PFOA and other perfluoroalkyl acids at water reclamation plants in South East Queensland Australia

This paper examines the fate of perfluorinated sulfonates (PFSAs) and carboxylic acids (PFCAs) in two water reclamation plants in Australia. Both facilities take treated water directly from WWTPs and treat it further to produce high quality recycled water. The first plant utilizes adsorption and filtration methods alongside ozonation, whilst the second uses membrane processes and advanced oxidation to produce purified recycled water. At both facilities perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA) were the most frequently detected PFCs. Concentrations of PFOS and PFOA in influent (WWTP effluent) ranged up to 3.7 and 16 ng L⁻¹ respectively, and were reduced to 0.7 and 12 ng L⁻¹ in the finished water of the ozonation plant. Throughout this facility, concentrations of most of the detected perfluoroalkyl compounds (PFCs) remained relatively unchanged with each successive treatment step. PFOS was an exception to this, with some removal following coagulation and dissolved air flotation/sand filtration (DAFF). At the second plant, influent concentrations of PFOS and PFOA ranged up to 39 and 29 ng L⁻¹. All PFCs present were removed from the finished water by reverse osmosis (RO) to concentrations below detection and reporting limits (0.4-1.5 ng L⁻¹). At both plants the observed concentrations were in the low parts per trillion range, well below provisional health based drinking water guidelines suggested for PFOS and PFOA.

Detection of anthropogenic gadolinium in treated wastewater in South East Queensland, Australia

The use of refractory gadolinium (Gd) complexes as paramagnetic contrast agents in magnetic resonance imaging has resulted in point source release of anthropogenic Gd (Gd(Anth)) into the environment, and presents opportunities to trace the fate of wastewater in natural environments. We demonstrate an inductively coupled plasma mass spectrometry (ICP-MS) technique that is capable of detecting Gd(Anth) at concentrations as low as 48 fM, approximately six orders of magnitude lower than most other micropollutants, without the need for preconcentration. Further, we establish the ubiquitous presence of Gd(Anth) in wastewater at eight separate wastewater treatment plants in Brisbane, Australia, over a 3-month time period. In contrast, there is no evidence of Gd(Anth) in tap water, or in four separate regional water supply dams in South East Queensland, Australia. It is, therefore, highly unlikely that other anthropogenic micropollutants sourced from urban wastewater would be present in the drinking water supply.

Aquatic geochemistry of the rare earth elements and yttrium in the Pioneer River catchment, Australia

The rare earth elements are strong provenance indicators in geological materials, yet the potential for tracing provinciality in surface freshwater samples has not been adequately tested. Rare earth element and yttrium concentrations were measured at 33 locations in the Pioneer River catchment, Mackay, central Queensland, Australia. The rare earth element patterns were compared on the basis of geological, topographical and land-use features in order to investigate the provenancing potential of these elements in a small freshwater system. The rare earth element patterns of streams draining single lithological units with minor land modification show strongly coherent normalised behaviour, with a loss of coherence in agricultural locations. Evidence is reported for an anthropogenic Gd anomaly that may provide a useful hydrological tracer in this region since the introduction of magnetic resonance imaging in 2003. Several samples display a superchondritic Y/Ho mass ratio (up to 44), which is not explainable within the constraints imposed by local geology. Instead, it is suggested that the additional Y is derived from a marine source, specifically marine phosphorites, which are a typical source of fertiliser phosphorus. The data indicate that, under some circumstances, scaled and normalised freshwater rare earth patterns behave conservatively.

Detection of anthropogenic gadolinium in the Brisbane River plume in Moreton Bay, Queensland, Australia

Wastewater effluent is known to contain macro and micropollutants, which may be deleterious to environmental health. One such class of micropollutants is chelated gadolinium, which are used as MRI contrast agents. As these MRI contrast agents can be assumed to behave conservatively during estuarine mixing, it is possible to calculate how much wastewater is represented in any particular sample. In this study, the percentage contribution of wastewater at specific locations in Moreton Bay, Qld, were determined by calculating the additional anthropogenic gadolinium contribution to the total rare earth element concentrations. Wastewater contributions were measured at concentrations as low as 0.2%, demonstrating the applicability of this technique for wastewater effluent plume mapping.

Reverse osmosis integrity monitoring in water reuse: The challenge to verify virus removal – A review

A reverse osmosis (RO) process is often included in the treatment train to produce high quality reuse water from treated effluent for potable purposes because of its high removal efficiency for salinity and many inorganic and organic contaminants, and importantly, it also provides an excellent barrier for pathogens. In order to ensure the continued protection of public health from pathogen contamination, monitoring RO process integrity is necessary. Due to their small sizes, viruses are the most difficult class of pathogens to be removed in physical separation processes and therefore often considered the most challenging pathogen to monitor. To-date, there is a gap between the current log credit assigned to this process (determined by integrity testing approved by regulators) and its actual log removal capability as proven in a variety of laboratory and pilot studies. Hence, there is a challenge to establish a methodology that more closely links to the theoretical performance. In this review, after introducing the notion of risk management in water reuse, we provide an overview of existing and potentially new RO integrity monitoring techniques, highlight their strengths and drawbacks, and debate their applicability to full-scale treatment plants, which open to future research opportunities.

Tracing treated wastewater in an inland catchment using anthropogenic gadolinium

The discharge of treated wastewater into natural water bodies occurs worldwide; if drinking water is then extracted downstream, there is potential for micropollutants that are not fully mineralized in the wastewater treatment process to enter municipal drinking water. In Australia, drinking water treatment is typically a mixture of basic technologies such as flocculation and slow sand filtration; technologies that are not specifically designed to remove micropollutants. However, there is little awareness in Australia of the potential risk that upstream wastewater discharges may impart to the security and quality of downstream drinking water supplies. We apply a direct inductively coupled plasma mass spectrometry technique to determine the discharge of anthropogenic gadolinium from a wastewater treatment plant in Toowoomba, Queensland, Australia, that discharges into the small (147 km(2)) catchment of Gowrie Creek. We then continue to measure the concentrations of this wastewater tracer as Gowrie Creek flows downstream into the Condomine River, and to a community 100 km away where drinking water is extracted. Using this tracer, we demonstrate that the community has a detectable wastewater contribution within their surface drinking water supply.

Removal of magnetic resonance imaging contrast agents through advanced water treatment plants

Stable gadolinium (Gd) complexes have been used as paramagnetic contrast agents for magnetic resonance imaging (MRI) for over 20 years, and have recently been identified as environmental contaminants. As the rare earth elements (REE), which include Gd, are able to be measured accurately at very low concentrations (e.g. Tb is measured at 7 fmol/kg in this study) using inductively coupled plasma mass spectrometry (ICP-MS), it is possible to determine the fate of this class of compounds during the production of purified recycled water from effluent. Coagulation and microfiltration have negligible removal, with the major removal step occurring across the reverse osmosis membrane where anthropogenic Gd (the amount of Gd attributable to MRI contrast agents) is reduced from 0.39 nmol/kg to 0.59 pmol/kg, a reduction of 99.85%. The RO concentrate has anthropogenic Gd concentrations of 2.6 nmol/kg, an increase in concentration in line with the design characteristics of the plant. The increased concentration in the RO concentrate may allow further development of anthropogenic Gd as a tracer of the fate of the RO concentrate in the environment.

Mangrove tree rings: A proxy for high-resolution environmental changes

Evidence of global climate change is expected to be first seen in polar regions, where subtle changes in climate may have large impacts on fragile geomorphic systems. Polar dunes are one such system for which there is little precise information available. For example, the extent to which polar aeolian deposits are stabilized by ice-bonded sands is unknown. As a first step towards a better understanding of the response of polar desert aeolian systems, we have mapped the sand dunes in Victoria Valley, Antarctica over the past four decades. The dune field is located at the confluence of the Packard and Victoria Valleys and has been the focus of field measurement programs for more than 40 years. Previous studies indicate that dune mobility has been limited to the crests shifting over ice-cemented sand layers within the dune in response to the Valley’s bi-direction wind regime. This is believed to impede net migration of the dune field. Short-term field studies have shown erratic movement of the dunes with the range between –14 and 62 m. However, no study has been made of longer term change in the morphological character of the dune field. In this study we use vertical air photographs and LIDAR data to map dune change over a 43 year period. We assess change in dune position and morphology over time. We find that the dunes have migrated (up to 75 m), and that dune form has changed, principally by lateral coalescing and limb extension. Movement of the dunes suggests that migration is possible despite the presence of ice and snow within the dune core. In addition, these changes support earlier observations that indicate a net (westerly) migration driven by topographically channeled thermally generated easterlies and gradient southeasterly winds. We infer this to indicate that the region has not undergone significant change in weather patterns in the last four decades. This is in agreement with the findings of Ayling and McGowan (2006) who investigated dust deposits on the adjacent Victoria Lower Glacier. Accordingly, it would appear that neither change in weather or climate due to global warming has caused significant change to the meteorology of the Victoria Valley, Antarctica and in-turn its aeolian geomorphic system.Plant macrofossils from permafrost deposits at the Bolshoy Lyakhovsky Island, New Siberian Archipelago, in the Russian Arctic were studied aiming at the revelation of climatic similarities and distinctions between the last and the current interglacial. The plant remains revealed the existence of a shrubland dominated by Alnus fruticosa, Betula nana, and Ledum palustre and interspersed with lakes and grasslands during the last interglacial. The reconstructed vegetation differs fundamentally from the high arctic tundra that exists in this region today, but resembles an open variant of subarctic shrub tundra as occurring near the tree line about 350 km southwest of the study site. Such difference in the plant cover implies that, during the last interglacial, the mean summer temperature was considerably higher, the growing season was longer, and soils outside the range of thermokarst depressions were drier than today. Pollen-based climatic reconstructions using the best modern analogue (BMA) approach suggest a mean temperature of the warmest month (MTWA) range of 914.5 °C during the warmest interval of the last interglacial. Reconstructions from plant macrofossils based on thermal minimum needs of included plants, representing more local environments, gained MTWA values above 12.5 °C in contrast to todays 2.8 °C. We explain this contrast in summer temperature and moisture conditions with a combination of summer insolation higher than present and climatic continentality in arctic Yakutia stronger than present as result of a considerably less inundated Laptev Shelf during the last interglacial. The project was funded by the German Research Foundation (DFG).Over two-thirds of northern and central Britain has been glaciated during the Quaternary, and the present landscape is a relict of the glacial processes that have acted to erode and redistribute large quantities of geological material. The landscape of Southern Britain by contrast, which lay largely beyond the maximum ice extent, was not subjected to such processes. Instead the present form of the landscape reflects approximately 2.5 million years of subaerial weathering under a climate regime, characterized since the onset of the Middle Pleistocene, by a long-term trend of periglacial-Interglacial-periglacial cycles operating with 100ka cyclicty. The effect of this, as preserved with the geological record, has been the extensive in-situ weathering of bedrock materials and the development of thick regolith. Since the region became populated, deforestation and cultivation has progressively removed the vegetation that once acted to stabilize the regolith, and the regolith material is now highly susceptible to erosion by hillwash and solifluction processes. This represents a significant ground stability hazard especially in relation to the subsidence and collapse of roads and property. In addition, large valley accumulations of regolith material can liquefy under prolonged periods of intense rainfall and can result in catastrophic flooding and landslide events, such as those that occurred in Lynmouth in 1952 and more recently, in Boscastle on the north Cornwall coast in 2004. This abstract reports the findings of research undertaken both to map the spatial extent of these regolith deposits, and also to understand what controls their local and regional distribution. The research, based upon field analysis and NEXTMAP digital terrain models from two test areas in southwest England, reveals that the spatial distribution of in-situ and soliflucted regolith material is largely controlled by lithological variability and structural complexity of the bedrock. It is hoped that these models will prove an invaluable to planners to enable informed decision making and the prediction of natural geohazards.QUAVIDA is a new project which aims to understand the interactions among vegetation structure and function, climate and fire regimes during the Late Quaternary. The project targets Australasia as a critical area in the development of a global picture of environmental change. Australasia has experienced major wet/dry, temperature and atmospheric CO2 fluctuations in the past; human arrival and occupation have also had a substantial environmental influence. Much of the vegetation within the region is fire-prone (and fire-adapted), with fire management long and widely practised. We need to understand the natural climate variability, disentangle the role of humans in past changes and investigate how plant types, vegetation and fire regimes will respond to future climate changes. QUAVIDA will do this by using state-of-the-art earth system models in hypothesis-testing mode, running simulations for specific times in the past but with different model components operative and using different scenarios of external and internal forcing. In order to evaluate and interpret these simulations, comprehensive data sets describing palaeoenvironmental conditions at key times in the past will be required. Thus, the first major focus of activity within QUAVIDA has been the creation of a comprehensive database of palaeoenvironmental information from Australasia, covering the last 70,000 years. The database contains radiometrically-dated pollen, phytolith, plant macrofossil, stickrat midden, carbon isotope and charcoal records. Interrogation of this database will yield benchmark reconstructions of vegetation patterns and fire regimes for the evaluation of the model simulations. Using more than one source of palaeoenvironmental information allows differences in the temporal and spatial scale of different kinds of observations to be taken into account in making reconstructions. It also allows for the fact that different sources record different aspects of climate and/or environmental changes. This presentation will introduce QUAVIDA, the methods and preliminary results of the palaeo-data synthesis, and discuss the project’s contribution to the international earth-modelling community.In February 2004, a 4 m core spanning the last ~ 40 ka was retrieved from Native Companion Lagoon (NCL), southeast Queensland, Australia using a Russian D-section corer. Analysis of the top 1 m of the core, which represents the Holocene, identified a pronounced increase in aeolian sedimentation commencing at ~5700 cal BP with peaks in the deposition of wind transported sediment of 12.5 g m−2a at 4690 cal BP and 10.8 g m−2a at 3890 cal BP before decreasing to 0.3 g m−2a at ~2000 cal BP. The increase in aeolian sedimentation ~5700 cal BP was coincident with a pronounced increase in charcoal content of the core, thereby indicating that fire was most likely a key agent in the destabilisation of the local dunes. Geochemical provenance of the long traveled dust component of the record identified western Queensland and southwestern New South Wales as the dominant source areas. Analysis of pollens from the core indicate a reduction in aquatics similar to that reported by Donders et al. (2006) for Lake Allom, Fraser Island, while there was also a reduction in rainforest and pteridophytes. As a result, we believe that this period of increased aeolian sedimentation was caused by prolonged and severe drought possibly linked to the onset of ENSO type conditions in the mid-Holocene as reported by Moy et al. (2002) and Gagan et al. (2004). Through analogy with contemporary ENSO events, precipitation bearing southeasterly trade winds would have been suppressed and replaced by more frequent and dry west to southwesterly winds as indicated by the provenance of far traveled dust to west and southwestern source areas. Importantly, the NCL record identifies southeast Queensland as a region susceptible to prolonged and severe drought as a consequence of more persistent ENSO type conditions. Recent modeling studies suggest that ENSO type conditions may transform from their current interannual variability into the mean climate as a consequence of global warming. Our results suggest that if this was to occur, then southeast Queensland may experience the onset of another arid phase.A high resolution pollen record from the ODP 820 marine core for the last million years is presented. It is chronologically controlled by marine stratigraphic data.This record provides a picture of substantial vegetation and environmental change for the humid tropics region of northeastern Australia. It is the first largely continuous record in Australia to cover this length of time in any detail, although sediment accumulation rates decrease with increasing age. The influence of orbital forcing (particularly eccentricity and obliquity) is clearly present in the record providing good support for the proposed age model based on the marine stratigraphy, but each isotope stage contains some distinctive features. Superimposed on these cyclical patterns are abrupt and sustained changes in the representation of many taxa and community types that may be explained by a combination of regional changes in oceanic and atmospheric circulation systems throughout this time period, along with the impacts of people in the later part of the record (i.e. last 45,000 years BP).