The study, an ambient-monitoring assessment rather than an investigation centred on known contamination sites, directly tested the assumption that commonly analysed PFAS are invariably present in surface waters. Concentrations were highest in waters adjacent to major urban and industrial areas, where mean total PFAS reached as much as 63 ng L−1 at one site. Levels were lower in inner and outer regional areas and lowest in remote locations. Of the 30 compounds targeted, 16 were not reported above the reporting limit at any site during the year. Nine sites with no reported PFAS lay in inner regional, outer regional and remote areas, while the nine sites where compounds other than PFOS appeared were all in major cities except for Vines Creek, an inner-regional site near an industrial estate, wastewater treatment plant and landfill in Mackay.

PFOS showed a measured range of less than 0.1 to 0.4 ng L−1 in remote areas, less than 0.1 to 0.6 ng L−1 in outer regional areas, less than 0.1 to 4.7 ng L−1 in inner regional areas and less than 0.1 to 37.0 ng L−1 in major cities. At 10 of the 45 sites where PFOS was reported, it appeared in fewer than half of the samples and at concentrations close to or at its 0.1 ng L−1 limit of reporting. PFOS was the only compound reported at 32 sites outside the major-city class, and most of those measurements were near the reporting limit. The study authors cautioned that PFOS had an order-of-magnitude lower reporting limit than the other PFAS, a difference that may partly explain why it was reported more frequently.

The monitoring network spanned six freshwater sites, one lake or reservoir, 42 estuarine sites and five coastal sites. Every location was at least 1 km from a wastewater treatment plant or another known PFAS point source, following guidance for global monitoring of persistent organic pollutants. Sites were selected to represent major-city, inner-regional, outer-regional and remote classifications across the eastern coast; 11 were in major cities, 26 in inner regional areas, nine in outer regional areas and eight in remote areas, with no very remote sites included. Surface-water grab samples were taken just below the surface at estuarine sites on an outgoing tide. Field and transport blanks and duplicate samples supported laboratory quality control, while an interlaboratory laboratory checked duplicates.

Each sample was analysed for 30 commonly examined PFAS by an accredited laboratory at the lowest available reporting limit. The investigators combined the concentration data with measurements of pH, turbidity, electrical conductivity, dissolved oxygen, temperature and salinity, as well as landscape and source-related variables. These included distance to the nearest known potential source, the number of licensed waste-management activities and wastewater treatment plants in the catchment, catchment population, catchment size, elevation, rainfall during the 30 days before collection, and remoteness class. Population estimates were calculated at two spatial scales, including a smaller catchment of roughly 150 km², so the analysis could consider both nearby populations and the wider area draining toward each site.

Spatial analysis identified several factors associated with PFOS concentrations. The strongest site-level correlation was with population in the smaller catchment, with a Spearman correlation coefficient of 0.71. PFOS was also associated with distance from the nearest known potential source, for which the correlation was −0.66, and with the number of waste-management activities in the catchment, at 0.60. The directions and significance of these associations persisted under different treatments of results below the reporting limit. A multivariable model containing remoteness class and population density had an adjusted R² of 0.63, indicating that the two variables together accounted for 63% of the observed variation in site-level PFOS after adjustment. These statistical relationships do not by themselves establish causation, but they are consistent with greater proximity to human infrastructure in densely settled areas.

Urban sites nevertheless displayed substantial local differences. Some locations near the Gold Coast and at the mouth of the Brisbane River had very low PFAS levels or none above the reporting limit. The researchers proposed that strong water movement and flushing in coastal estuaries may dilute contaminants, particularly where potential sewage discharge points are offshore. In contrast, upstream sites in the Brisbane River experienced longer residence times and had higher concentrations. Oxley Creek and the Brisbane River at Indooroopilly were directly linked by their geography: the river site was downstream of the Oxley Creek wastewater treatment plant discharge and about 3 km upstream of the creek’s confluence with the river. These site-specific hydrological conditions help explain why proximity to a city did not translate into a uniform concentration pattern across urban waters.

Three sites exceeded the Australian and New Zealand default guideline value of 20 ng L−1 for PFOS, a value intended to protect 99% of aquatic species: Brisbane River at Indooroopilly reached 37 ng L−1, Oxley Creek reached 30 ng L−1 and Mary River at Maryborough reached 21 ng L−1. The Mary River result was an anomaly because PFOS was at or below the 0.5 ng L−1 interim screening threshold, or below the reporting limit, during every other monitoring round, and its source was not identified. Nine sites had no reported PFOS, and 26 had maximum concentrations below the interim screening threshold. Seventeen sites exceeded that threshold but remained below the stricter default guideline value. Sites with PFOS above the threshold were confined to major-city and inner-regional classes; neither outer-regional nor remote sites exceeded it.

Monitoring also captured different temporal patterns at individual locations rather than a single statewide trend. PFAS increased during the dry season at the Brisbane River’s Karana Downs site and in the Caboolture River. Both are tidal estuaries about a kilometre upstream from licensed sewage discharge points, and both experience their greatest flow during the wet season; the researchers identified effluent discharge as a possible contributor to dry-season accumulation. Oxley Creek and Brisbane River at Indooroopilly instead showed wet-season increases, which the authors associated with stormwater runoff from industrial areas and wet-weather wastewater releases. Tingalpa Creek showed no clear seasonal pattern, possibly reflecting its multiple upstream sources. An opportunistic Bramble Bay sample taken after heavy rain contained approximately six times the total PFAS seen in other months and included PFPeA, PFHxA, PFOA and PFHxS in addition to PFOS.

The authors emphasised several limitations in interpreting the statewide picture. The network was weighted toward coastal and estuarine sites because locations were drawn from an existing monitoring program, leaving only six freshwater sites and limited representation farther inland. Some laboratory reporting limits were higher than those in newer literature, and the number of PFAS described and analysed has continued to grow. The seasonal analysis was possible at only six South East Queensland sites that had at least one PFAS reported in every sampled month, so the observed wet- and dry-season patterns should be interpreted as site-specific responses rather than evidence of a general Queensland cycle. Unrecorded septic systems, recycled-water irrigation, biosolid and pesticide applications, and potential atmospheric deposition could also influence results. Longer monitoring across more freshwater and inland sites, together with more complete source records, will be required to determine how widely the observed patterns extend across Queensland.

Subject of Research: Ambient monitoring of 30 PFAS across 54 surface-water sites along Queensland’s eastern coast.

Article Title: Not everywhere, not always: 30 targeted PFAS in ambient surface waters of Queensland, Australia

Article References: Baddiley, B., Myburgh, A., & Vardy, S. (2026). Not everywhere, not always: 30 targeted PFAS in ambient surface waters of Queensland, Australia. Environmental Monitoring and Assessment, 198(11), Article 1232. https://doi.org/10.1007/s10661-026-16030-5

Image Credits: AI Generated

DOI: 10.1007/s10661-026-16030-5

Keywords: PFAS, PFOS, Queensland, surface water, ambient monitoring, environmental contamination, urban pollution, water chemistry, Australia, remoteness, everywhere, always

The birds in the study were not killed for research. All 24 cadavers arrived opportunistically between June 2022 and November 2023, a window that coincided with regional mouse infestations. Some were donated by the university’s Veterinary Teaching Hospital after being euthanised for medical reasons, while others were roadkill collected during unrelated fieldwork. Ten raptor species and one nightjar were represented, with Eastern Barn Owls dominating the sample at ten individuals, followed by three Australian Boobook Owls. Two Wedge-tailed Eagles, two Black-shouldered Kites, a Peregrine Falcon, a Powerful Owl, a Grey Goshawk, a Brown Goshawk, a Nankeen Kestrel, a Black Kite and a Tawny Frogmouth rounded out the list. Thirteen birds were male, ten female and one of undetermined sex; fourteen were adults and ten immature.

The analytical centrepiece of the study was liquid chromatography mass spectrometry, or LC-MS, performed at the CSIRO Ecosciences Precinct in Brisbane. Because decay alters the water content of tissue, the researchers homogenised and freeze-dried liver samples before extraction, then used a multi-step process involving formic acid, cold acetonitrile and lipid-removal cartridges to isolate the rodenticide residues. The instrument, an Agilent 6546 liquid chromatography quadrupole time-of-flight mass spectrometer, ran in a data-independent mode called quadrupole-resolved all-ions analysis, screening for eight rodenticides including warfarin, brodifacoum, difethialone, flocoumafen, bromadiolone, difenacoum, coumatetralyl and pindone. Calibration curves spanning 0.01 to 1,000 parts per billion achieved correlation coefficients between 0.9683 and 0.9971, and quality-control samples spiked with known concentrations of the compounds verified the method’s accuracy across low, mid and high ranges.

The results were striking. Thirteen of the 24 birds, just over half, tested positive for rodenticides registered for use in Australia. The most frequently detected compound was warfarin, a first-generation anticoagulant, found in eleven birds. Second-generation anticoagulants, which are far more toxic and persistent, also appeared: brodifacoum in three samples, difethialone in one and flocoumafen in one. Three birds carried warfarin alongside a second-generation compound, meaning they had been exposed to multiple poisons. Perhaps most telling, only six of the thirteen rodenticide-positive birds had rodent remains in their digestive tracts at the time of death. The researchers interpret this as evidence that the poisons can bioaccumulate in liver tissue over time, lingering from past meals of poisoned prey rather than reflecting a single recent exposure.

None of the detected concentrations reached the lethal dose thresholds established for other bird species. Brodifacoum levels in the Barn Owls and a Wedge-tailed Eagle fell below the reported oral LD50 range for owls of 0.15 to 9.68 milligrams per kilogram, and the difethialone concentration in the Tawny Frogmouth, 0.1 milligrams per kilogram, sat below the LD50 values of 0.26 to 23.4 milligrams per kilogram documented for Bobwhite, Japanese Quail and Mallard. Warfarin concentrations were similarly far below the 525 to 2,150 milligrams per kilogram lethal range reported for those same test species. But sublethal does not mean harmless. Second-generation anticoagulants are highly lipid-soluble and resist metabolic breakdown, and brodifacoum has been shown to cause persistent coagulopathy in birds for up to eleven days even at doses below the lethal threshold.

The clinical consequences of such exposure can be subtle but deadly. Birds suffering sublethal anticoagulant toxicosis have been documented to show lethargy, reduced agility and wing droop, impairments that degrade hunting performance and spatial navigation. For a fast-flying owl hunting at night, a momentary lapse in coordination can be fatal in a different way: collision with a vehicle. Twelve of the fifteen birds in the study showing traumatic injuries were found on roadsides, and the authors suggest that some of these roadkill birds may have been compromised by sublethal poisoning before they ever met a car. Peak coagulopathy after a single lethal ingestion typically occurs one to four days later, and after sublethal ingestion the effects may take even longer to manifest, widening the window of vulnerability.

Disentangling poisoning from trauma is one of the study’s central methodological challenges. Internal bleeding looks much the same whether it stems from a blunt impact or a drug-induced failure of the clotting cascade, and decomposition or scavenging can destroy clots that would otherwise distinguish the two. Ten birds showed haemocoelom, a coelomic cavity filled with uncoagulated blood, and in six of those there were no grossly obvious external signs of trauma such as fractures or lacerations. Yet only four of the ten haemocoelom cases were rodenticide-positive, and the statistical association between anticoagulant presence and postmortem evidence of coagulopathy was not significant. Alternative causes of bleeding disorders complicate the picture further: three birds carried low-burden apicomplexan parasites consistent with avian malaria, two had chronic enteritis with coccidian oocysts possibly of the genus Goussia, and heavy metal toxicity and bacterial infections such as salmonellosis can produce similar pathology in wild raptors.

One statistically significant pattern did emerge, and it concerned age. Immature birds were significantly more likely to carry higher brodifacoum concentrations than adults, a correlation with an f-value of 5.15 and a p-value of 0.03. The authors offer several non-exclusive explanations: inexperienced young hunters may target weakened, poisoned prey more readily; older birds may metabolise or eliminate the compound more efficiently or simply have longer intervals between exposures; or heavily affected juveniles may never survive to adulthood at all. The researchers caution, however, that the small sample size and a confidence interval hovering near zero mean the finding should be treated as a hypothesis generator rather than a settled conclusion. Species-level dietary differences add another layer of complexity, since rodent specialists such as Barn Owls and Black-shouldered Kites face theoretically higher exposure risk than bird-eating specialists like goshawks.

The conservation stakes extend beyond the species examined, all of which are currently listed as Least Concern by the International Union for Conservation of Nature. The Powerful Owl, despite its global status, numbers only an estimated 2,200 to 2,800 mature individuals, and the Grey Goshawk is estimated at fewer than 10,000 birds with a declining trend and Endangered classification in several Australian states. Sublethal poisoning that reduces foraging success, body condition and reproductive output, effects documented in vulture studies in the Pacific Northwest, could push such populations toward localised declines long before outright poisoning deaths register. Australian raptor populations remain poorly studied overall, making it difficult to assess how much hidden damage rodenticides are doing.

The study’s most policy-relevant finding may be its challenge to current Australian guidelines, which favour first-generation rodenticides such as warfarin over second-generation products on the assumption that they break down faster in rodents and pose less secondary risk. Warfarin was, after all, the most common residue in these Queensland birds. The authors point instead to coumatetralyl, another first-generation anticoagulant regarded as safer for predatory birds: mammals are generally more sensitive to it than birds, allowing lower effective doses, and while warfarin resistance has been documented in Australian rodents, no coumatetralyl resistance has yet been recorded there. The team calls for physiological studies of exposed raptors, rodent toxicity testing to track resistance, and surveys of rodenticide users to map what, how much and how often is being deployed. Until then, the poisons meant for mice appear to be quietly accumulating in the livers of the owls, eagles and falcons that share those fields, a debt the ecosystem may only now be beginning to itemise.

Subject of Research: Sublethal anticoagulant rodenticide exposure in deceased predatory birds in south-east Queensland, Australia

Article Title: Evaluating sublethal anticoagulant rodenticide exposure in deceased predatory birds of South-East Queensland, Australia

Article References: Low, Z., Murray, P. J., Naseem, N., McGilp, D., Doneley, B., Beale, D. J., Biggs, L., & Gonzalez-Astudillo, V. (2024). Evaluating sublethal anticoagulant rodenticide exposure in deceased predatory birds of South-East Queensland, Australia. Discover Toxicology, 1(1), Article 13. https://doi.org/10.1007/s44339-024-00016-4

Image Credits: AI Generated

DOI: 10.1007/s44339-024-00016-4

Keywords: anticoagulant rodenticides, raptors, owls, warfarin, brodifacoum, secondary poisoning, wildlife toxicology, LC-MS, Australia, Queensland, coagulopathy, conservation

The snail at the center of the study, Figuladra bayensis, is a banded land snail native to the forests of Queensland. Like trees, snails add material to their shells incrementally, producing growth bands that can be sampled and analyzed one by one. A project led by researchers in the University of Queensland’s School of the Environment took tiny samples of the shell at millimetre intervals, a resolution fine enough to resolve individual growth episodes within the animal’s lifespan. Each band, the team realized, potentially encoded both a timestamp and a weather report: the chemistry of the carbonate laid down at any moment reflects the environmental conditions the snail was experiencing as it secreted new shell material.

Dating those bands precisely was the first challenge, and the researchers turned to one of the most distinctive chronological tools of the modern era: the radiocarbon signature left by atmospheric nuclear testing. During the 1950s and 1960s, nuclear weapons tests, including tests conducted in Australia, injected large quantities of artificial radiocarbon into the atmosphere. This so-called bomb pulse was absorbed by plants, incorporated into the food chain, and ultimately recorded in the tissues and shells of animals alive at the time. Dr Nicholas Patton, who led the project, explained that the shell contained elevated levels of radiocarbon from the nuclear tests of the 1960s. Using high-resolution radiocarbon dating, the team was able to anchor the growth bands in time and determine that the snail had lived for approximately four and a half years.

With the chronology established, the researchers analyzed the stable isotopes of oxygen and carbon preserved in each band. Oxygen isotope ratios in shell carbonate are governed largely by the isotopic composition of the water the animal ingests, which in turn is strongly influenced by the source and amount of rainfall in the local environment. Carbon isotopes reflect the animal’s diet and the photosynthetic pathways of the plants it consumed. Together, these two proxies provide a complementary picture of the climate and ecology surrounding the snail as it grew. By reading the isotope values band by band, the team could reconstruct a timeline of the rainfall conditions the snail experienced across the roughly four and a half years of its life.

What the team expected to find was a straightforward relationship between shell growth and annual climate. Honorary Professor Jamie Shulmeister, a co-author of the study, said the researchers initially anticipated that the rapid growth phases would correspond to years with heavier rainfall, which would have made more food available for the snail and fueled faster shell deposition. The logic seemed sound: wetter years should mean lusher vegetation, better nutrition, and more vigorous growth. But when the team compared the growth record against the meteorological history of the region, the expected pattern failed to appear. The shell’s growth was not tracking the overall wetness of each year at all.

Instead, the data revealed something far more striking. The shell had not grown continuously during the snail’s life; rather, there were periods of rapid growth separated by periods of little or no growth. When the researchers mapped these growth spurts against the dates established by radiocarbon dating, they found that the spurts aligned with periods immediately following two major tropical cyclones: Severe Tropical Cyclone Marcia in 2015 and Tropical Cyclone Debbie in 2017. Both storms caused extreme rainfall within Coalstoun Lakes National Park, dumping extraordinary volumes of water on the landscape in short periods. The snail, it turned out, was responding not to the gentle accumulation of seasonal rain but to the deluges that follow catastrophic storms.

The implications of this finding extend well beyond the biography of one snail. Because the growth spurts in the shell could be linked so clearly to specific, dated cyclones, the researchers recognized that snail shells could serve as proxies for extreme weather events extending back into periods before modern meteorological records began. Shulmeister described the realization as surprising and quite exciting, noting that the humble snail could become a tool for reconstructing the paths of past cyclones, potentially even in prehistoric times. For a region like the Queensland coast, where tropical cyclones pose a recurrent hazard, a new archive of pre-instrumental storm activity would be scientifically and socially invaluable.

The value of such an archive is difficult to overstate. Instrumental records of cyclone activity in Australia span little more than a century, and reliable satellite-based monitoring only a few decades. Beyond that window, scientists depend on sparse historical documents, geological storm deposits, and natural proxies such as coral cores and tree rings, each with its own limitations. Land snail shells, by contrast, are abundant, widely distributed, and durable enough to survive in sediment layers for thousands of years. If each shell preserves a chemical fingerprint of the extreme rainfall events during its lifetime, then a stratified sequence of shells could yield a decade-by-decade, or even finer, chronology of past storminess.

The research team’s next step is to test exactly that proposition. Dr Patton explained that if shells can be found within different layers of sediment deposits, the individual shell records can be combined to extend the information further back in time. Stacking multiple shell chronologies from successive sediment layers would, in principle, allow researchers to build a continuous reconstruction of extreme rainfall and cyclone activity across centuries or millennia. Such a reconstruction would help answer pressing questions about the natural variability of cyclone frequency in the Southwest Pacific, providing a baseline against which the influence of modern climate change on storm behavior can be assessed.

The study was completed in collaboration with Professor Melanie Leng of the British Geological Survey and the University of Nottingham, and Dr Quan Hua of the Australian Nuclear Science and Technology Organisation, institutions whose expertise in stable isotope analysis and radiocarbon dating underpinned the technical achievement of the work. The research, published in The Holocene under the title evaluating the Biggenden Banded Snail as a climate archive for South East Queensland using stable isotopes and radiocarbon dating, was conducted as an experimental study, and the authors declared no potential conflicts of interest. For now, the finding stands as a reminder that some of the most valuable scientific archives are not locked in ice cores or deep-sea sediments, but carried quietly on the backs of creatures small enough to fit in a palm, patiently recording the fury of the skies above them one growth band at a time.

Subject of Research: Land snail shells as climate archives for reconstructing historical and prehistoric cyclone activity in Queensland, Australia

Article Title: Snail shells are surprise weather time capsules

Article References: Snail shells are surprise weather time capsules. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: snail shells, paleoclimatology, cyclones, radiocarbon dating, stable isotopes, Queensland, extreme rainfall, The Holocene, University of Queensland, climate proxies, Figuladra bayensis, bomb pulse