Stuck in the mangrove mud: The risk of trace element exposure to shore crabs in restored urban mangroves.

The restoration of mangroves in urban environments can increase the risk of contaminant exposure and subsequent health effects to resident biota, yet this risk is rarely considered in mangrove restoration programs. Here we assessed the influence of sediment chemistry on contaminant bioaccumulation in shore crabs from restored and natural mangroves in urban environments compared to a reference site. The concentrations of some trace elements were several-fold higher in the sediment and crab tissues of the urban restored site compared to the natural reference site (Cd = 6×, Co = 7×, Cr = 4×, Mn = 30×, and Ni = 18× greater in sediments, while Cd = 4×, Co = 2×, Cr = 2×, Mn = 6×, and Ni = 3× greater in crab tissues).

Trace metal distribution in seagrass-vegetated sediments of an urbanized estuary in Queensland, Australia.

Seagrasses increase sediment complexity by trapping particulates and influencing biogeochemical cycles via root oxygen loss and organic matter exudation. However, their impact on trace metal sequestration is poorly studied. We found significantly higher trace metal concentrations in seagrass sediments compared to adjacent bare sediments, correlating with total organic carbon, iron, and fine sediments.

From land to sea: Environmental DNA is correlated with long-term water quality indicators in an urbanized estuary.

Estuaries provide critical ecosystem services, and yet are increasingly under threat from urbanization. Non-invasive approaches to monitor biodiversity resident to or migrating through estuaries is critical to evaluate the holistic health of these ecosystems, often based entirely on water quality. In this study we compared tree of life metabarcoding (ToL-metabarcoding) biodiversity detections with measurements of physico-chemical variables (chlorophyll a, turbidity, total nitrogen, total phosphorous, dissolved oxygen) at eight sites of varying degrees of water quality in the Gold Coast Broadwater Estuary (Queensland, Australia).

Satellite-based estimation of total suspended solids and chlorophyll-a concentrations for the Gold Coast Broadwater, Australia.

Satellite retrieval of total suspended solids (TSS) and chlorophyll-a (chl-a) was performed for the Gold Coast Broadwater, a micro-tidal estuarine lagoon draining a highly developed urban catchment area with complex and competing land uses. Due to the different water quality properties of the rivers and creeks draining into the Broadwater, sampling sites were grouped in clusters, with cluster-specific empirical/semi-empirical prediction models developed and validated with a leave-one-out cross validation approach for robustness. For unsampled locations, a weighted-average approach, based on their proximity to sampled sites, was developed.

Dose metric evaluation of a cell-based bioassay for assessing the toxicity of metals to Dugong dugon: Effect of metal-media interactions on exposure concentrations.

Cell-based toxicity testing has emerged as a useful tool in (eco)toxicological research, allowing the ethical assessment of the effects of contaminants such as trace metals on marine megafauna. However, metal interactions with various dissolved ligands in the microplate environment may influence the effective exposure concentrations. Hence, the cells are not exposed to the nominal concentrations within the test system.

Baseline water quality of the Gold Coast Broadwater, southern Moreton Bay (Australia).

This study establishes baseline water quality characteristics for the Gold Coast Broadwater, southern Moreton Bay (Australia) utilising routinely monitored parameters between 2016 and 2021, across 18 sites. Combined site mean concentrations of NO-N, NH-N and total nitrogen were 11.4 ± 33.

Metal forms and dynamics in urban stormwater runoff: New insights from diffusive gradients in thin-films (DGT) measurements.

Stormwater runoff typically contains significant quantities of metal contaminants that enter urban waterways over short durations and represent a potential risk to water quality. The origin of metals within the catchment and processes that occur over the storm can control the partitioning of metals between a range of different forms. Understanding the fraction of metals present in a form that is potentially bioavailable to aquatic organisms is useful for environmental risk assessment.

Circulating trace elements for the prediction of preeclampsia and small for gestational age babies.

Introduction: Poor gestational outcomes due to placental insufficiency can have lifelong consequences for mother and child.

Objective: There is a need for better methods of diagnosis, and elemental metabolomics may provide a means to determine the risk of gestational disorders.

Methods: This study used blood plasma samples collected at 36 weeks' gestation from women who later developed preeclampsia (n = 38), or small-for-gestational age babies (n = 91), along with matched controls (n = 193).

Synchrotron-Based Imaging Reveals the Fate of Selenium in Striped Marsh Frog Tadpoles.

Synchrotron-based X-ray fluorescence microscopy (XFM) coupled with X-ray absorption near-edge structure (XANES) imaging was used to study selenium (Se) biodistribution and speciation in tadpoles. Tadpoles were exposed to dissolved Se (30 μg/L) as selenite (Se) or selenate (Se) for 7 days followed by 3 days of depuration. High-resolution elemental maps revealed that Se partitioned primarily in the eyes (specifically the eye lens, iris, and retinal pigmented epithelium), digestive and excretory organs of Se-exposed tadpoles.

Coastal bays and coral cays: Multi-element study of Chelonia mydas forage in the Great Barrier Reef (2015-2017).

There is increasing interest in understanding potential impacts of complex pollutant profiles to long-lived species such as the green sea turtle (Chelonia mydas), a threatened megaherbivore resident in north Australia. Dietary ingestion may be a key exposure route for metals in these animals and marine plants can accumulate metals at higher concentrations than the surrounding environment. We investigated concentrations of 19 metals and metalloids in C.

Elemental Metabolomics for Prediction of Term Gestational Outcomes Utilising 18-Week Maternal Plasma and Urine Samples.

A normal pregnancy is essential to establishing a healthy start to life. Complications during have been associated with adverse perinatal outcomes and lifelong health problems. The ability to identify risk factors associated with pregnancy complications early in gestation is vitally important for preventing negative foetal outcomes.

Antimony and arsenic speciation, redox-cycling and contrasting mobility in a mining-impacted river system.

The Macleay River in eastern Australia is severely impacted by historic stibnite- and arsenopyrite-rich mine-tailings. We explore the partitioning, speciation, redox-cycling, mineral associations and mobility of antimony and arsenic along >70 km reach of the upper Macleay River. Elevated Sb/As occur throughout the active channel-zone and in floodplain pockets up to the regolith margin, indicating broad dispersal during floods.

DGT and selective extractions reveal differences in arsenic and antimony uptake by the white icicle radish (Raphanus sativus).

Increasing soil contamination of arsenic (As) and antimony (Sb) is posing a serious concern to human health. Due to insufficient studies on Sb, the biogeochemical behaviour and plant uptake of Sb are assumed to be similar to that of As. As part of extensive research unravelling As and Sb biogeochemistry and plant uptake, the diffusive gradients in thin films (DGT) technique and sequential extraction procedure (SEP) were applied to evaluate As and Sb uptake by the white icicle radish (Raphanus sativus) cultivated in diluted cattle dip soils contaminated with As only and diluted mining soils contaminated with both As and Sb under agricultural conditions.

A new colorimetric DET technique for determining mm-resolution sulfide porewater distributions and allowing improved interpretation of iron(II) co-distributions.

Measurement of sulfide in pore waters is critical for understanding biogeochemical processes, especially within coastal sediments. Here we report the development of a new colorimetric DET (diffusive equilibration in thin films) technique for determining mm-resolution, two-dimensional sulfide distributions in sediment pore waters. This colorimetric sulfide DET method was based on the standard spectrophotometric methylene blue assay, but modified to allow quantitation of sulfide by computer imaging densitometry.

Elemental metabolomics in human cord blood: Method validation and trace element quantification.

Background: Trace elements are an essential requirement for human health and development and changes in trace element status have been associated with pregnancy complications such as gestational diabetes mellitus (GDM), pre-eclampsia (PE), fetal growth restriction (FGR), and preterm birth. Elemental metabolomics, which involves the simultaneous quantification and characterisation of multiple elements, could provide important insights into these gestational disorders.

Methods: This study used an Agilent 7900 inductively coupled plasma mass spectrometer (ICP-MS) to simultaneously measure 68 elements, in 166 placental cord blood samples collected from women with various pregnancy complications (control, hypertensive, PE, GDM, FGR, pre-term, and post-term birth).

Comparison of DET, DGT and conventional porewater extractions for determining nutrient profiles and cycling in stream sediments.

Determining inorganic nutrient profiles to support understanding of nitrogen transformations in stream sediments is challenging, due to nitrification and denitrification being confined to particular conditions in potentially heterogeneous sediment influenced by benthic microalgae, rooted aquatic plants and/or diel light cycles. The diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques allow in situ determination of porewater concentration profiles, and distributions for some solutes. In this study, DGT, DET and conventional porewater extraction (sectioning and centrifugation) methods were compared for ammonium and nitrate in stream sediments under light and dark conditions.

NMR-based lipidomics of fish from a metal(loid) contaminated wetland show differences consistent with effects on cellular membranes and energy storage.

Metals and metalloids are priority contaminants due to their non-degradable and bioaccumulative nature, and their ability to regulate and perturb diverse physiological processes in various species. Metal(loid)s are known to cause oxidative stress through production of reactive oxygen species (ROS), thus related endpoints like lipid peroxidation (LPO) have received considerable attention as biomarkers of exposure. However, the implications of metal(loid) toxicity including LPO on actual lipid profiles of species inhabiting contaminated systems are poorly understood.

Oxygen loss from seagrass roots coincides with colonisation of sulphide-oxidising cable bacteria and reduces sulphide stress.

Seagrasses thrive in anoxic sediments where sulphide can accumulate to phytotoxic levels. So how do seagrasses persist in this environment? Here, we propose that radial oxygen loss (ROL) from actively growing root tips protects seagrasses from sulphide intrusion not only by abiotically oxidising sulphides in the rhizosphere of young roots, but also by influencing the abundance and spatial distribution of sulphate-reducing and sulphide-oxidising bacteria. We used a novel multifaceted approach combining imaging techniques (confocal fluorescence in situ hybridisation, oxygen planar optodes, and sulphide diffusive gradients in thin films) with microbial community profiling to build a complete picture of the microenvironment of growing roots of the seagrasses Halophila ovalis and Zostera muelleri.

Untargeted NMR-based metabolomics for field-scale monitoring: Temporal reproducibility and biomarker discovery in mosquitofish (Gambusia holbrooki) from a metal(loid)-contaminated wetland.

There is considerable interest in applying omics techniques, which have proven extremely valuable for laboratory-based toxicology studies, towards field-scale ecotoxicology and environmental monitoring. Concerns that confounding factors in natural ecosystems may exacerbate variability in omics datasets must be addressed to validate the transition from laboratory to field. This study explores how temporal variability related to seasonal and climatic trends influence qualitative and quantitative metabolomics outcomes, in fish from reference and metal(loid)-polluted wetlands in Australia.

Contrasting effects of bioturbation on metal toxicity of contaminated sediments results in misleading interpretation of the AVS-SEM metal-sulfide paradigm.

In undisturbed, metal-contaminated marine sediments, porewater metal concentrations are generally low due to their associations with strong binding phases such as organic matter, Fe/Mn (oxy)hydroxides and sulfides. Bioturbating fauna can alter redox conditions and, therefore, metal binding, potentially leading to increased metal bioavailability and subsequent toxicity to inhabiting organisms. Here we assessed the impacts of bioturbation (by bivalves and large amphipod species) on sediment biogeochemistry, metal bioaccumulation and toxicity to a smaller amphipod species in a metal contaminated sediment with low and high acid volatile sulfide (AVS) concentrations.

Assisted natural recovery of hypersaline sediments: salinity thresholds for the establishment of a community of bioturbating organisms.

Hypersaline sediments derived from poor land management or the decommissioning of large-scale salt production contribute to the long-term degradation of aquatic environments. Obstacles impeding remediation of these environments include salt crusts restricting benthic recolonisation, hypersalinity-induced toxicity to organisms, and disruption of biogeochemical cycles. Remediation often focuses on engineered solutions, despite sediment-biota interactions often playing a crucial role in improving long-term remediation and restoration of contaminated areas.

Diffusive Gradients in Thin Films Reveals Differences in Antimony and Arsenic Mobility in a Contaminated Wetland Sediment during an Oxic-Anoxic Transition.

Antimony (Sb) and arsenic (As) are priority environmental contaminants that often co-occur at mining-impacted sites. Despite their chemical similarities, Sb mobility in waterlogged sediments is poorly understood in comparison to As, particularly across the sediment-water interface (SWI) where changes can occur at the millimeter scale. Combined diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques provided a high resolution, in situ comparison between Sb, As, and iron (Fe) speciation and mobility across the SWI in contaminated freshwater wetland sediment mesocosms under an oxic-anoxic-oxic transition.

Development and evaluation of a new diffusive gradients in thin-films technique for measuring organotin compounds in coastal sediment pore water.

Organotins present a toxicological risk to biota in the aquatic environment. Understanding the behaviour of these compounds in sediment is challenging, with sophisticated analytical techniques required for their measurement. We investigated the use of silica-bound sorbents for diffusive gradients in thin-films (DGT) adsorption gels to pre-concentrate five organotins (monobutlytin (MBT), dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPhT), triphenyltin (TPhT)) found frequently in coastal sediment.

A modified DGT technique for the simultaneous measurement of dissolved inorganic nitrogen and phosphorus in freshwaters.

A modified diffusive gradients in thin films (DGT) technique uses both a mixed binding layer (PrCH and A520E resins for NH-N and NO-N, respectively) and multiple binding layers (Metsorb binding layer for PO-P overlying the mixed binding layer) for the simultaneous measurement of dissolved inorganic nitrogen (nitrate and ammonium) and phosphate in freshwater (INP-DGT). High uptake and elution efficiencies were determined for a mixed (PrCH/A520E) binding gel for dissolved inorganic nitrogen and an agarose-based Metsorb binding layer for PO-P. Diffusion coefficients (D) obtained from DGT time-series experiments (conductivity 180 μS cm) for NH-N, NO-N and PO-P agreed well with those measured using individual DGT techniques in previous studies, but were characterised over a wider range of ionic strengths here.