The degradation performance and mechanisms of 3D printed geopolymers (3DPG) under atmospheric (atmospheric zone, AZ), seawater submerged (submerged zone, SZ), intertidal (tidal zone, TZ) conditions over 12 months exposure were evaluated by monitoring their large-scale properties (apparent morphology, mass change, mechanical behavior), combined with microstructural analysis of pore structure and reaction product distribution, aggressive ions' penetration depth and distribution. AZ samples showed minimal mass change and steadily increasing strength over time. SZ samples' mass increased due to salt absorption, but surface aggregate precipitates; the mechanical strength first increased and then decreased. TZ samples' mass continuously losses, the mechanical strength first increased and then decreased. Notably, adding healing agent significantly enhanced the mechanical properties of 3DPG. 3DPG exhibited vertical layering pore distribution characteristics and had no high interlayer porosity defects after seawater erosion. With increasing erosion time, porosity increased in AZ samples; both SZ and TZ samples experienced decreasing porosity and reduced pore throat number and length. After seawater erosion, AZ samples formed geopolymer gel, Ca(OH)(2), CaCO3, with minimal Cl- or SO42- penetration. SZ samples have geopolymer gel with deeper Cl- penetration (6.0 mm) and SO42- intrusion (2.0 mm). TZ samples contained gel and CaSO4, showing the deepest Cl- infiltration (>10.0 mm) and an SO42- enrichment peak at 2.0 mm depth. Prolonged erosion progressively leached Ca(2+ )from SZ and TZ samples, causing geopolymer decalcification, increasing the Na/Ca ratio, disrupting the gel's change balance and structural integrity, distorting the 3D network, reducing stability, with salt recrystallization caused by tidal action exacerbating damage.

Natural fiber textiles, such as cotton, are widely marketed as greener, biodegradable materials within the fashion and textiles industry. However, contemporary environmental assessments of whole (plastic and non-plastic) textile fiber pollution regularly find natural, not plastic, fibers dominate environmental samples. Here we combine palaeolimnological, archival, and forensic science methodologies to evaluate long-term fiber preservation in sediments. We recover individual textile fibers from a unique 150-year lake sediment record from Rudyard lake, Staffordshire, UK. Between c.1876 and c.1979, all bar two fibers recovered from this sediment were natural. After c.1979, fiber accumulation rates increase, driven primarily by an increase in cotton accumulation. These data challenge assumptions of natural fiber biodegradability and add to the technofossil record of historic human activity. We conclude that there is a pressing need to reconsider whether natural textile fibers are as benign as is largely assumed, particularly in pursuit of plastic alternatives for fashion and textiles.

Risk-based land management emphasises remediation to manage risks from land contamination, aiming to reduce human and environmental risks while enabling site reuse and redevelopment. Since the mid-2000s, sustainable remediation has gained prominence, driven by global sustainability agendas such as the United Nations 2030 Agenda and the European Green Deal. These frameworks encourage integrated approaches that maximise remediation benefits and minimise negative impacts. Low-input remediation techniques (LIRT) represent a family of approaches characterised by lower energy and resource demands, often leveraging natural processes, renewable resources, or energy sources. Examples include methods using biochar, photosynthesis, or renewable energy systems. LIRT overlap with concepts like gentle remediation options (GRO) and nature-based solutions (NBS), which employ natural processes to address contamination while delivering environmental and societal benefits. While LIRT are typically effective for pathway management rather than source control, they offer sustainable outcomes such as stabilisation, containment, and destruction of biodegradable contaminants. They also contribute to broader sustainability goals, such as reducing carbon footprints and preserving soil functionality, and can support site reuse for biofeedstocks, habitats, or amenity spaces. LIRT are particularly valuable for stalled or economically unviable sites, offering cost-effective and flexible solutions. However, achieving sustainable outcomes depends on site-specific factors, and LIRT often work best when integrated into a broader remedial strategy combining intensive and low-input methods. This paper explores LIRT's potential applications, technical characteristics, and challenges, alongside their benefits for sustainable land management and the restoration of underutilised sites.

The term ‘Anthropocene’ was coined in recognition that human activities have ended the relatively stable environment of the Holocene epoch. However, its widespread adoption across the humanities, arts and sciences has led to diverse and sometimes incompatible definitions. In this Perspective, we argue for a stabilized definition of the Anthropocene epoch to help address contemporary environmental challenges, and explore various applications of the Anthropocene across disciplines. The Anthropocene epoch, with a proposed start point in 1952, underscores that human-driven global-scale environmental disruption differs from earlier human impacts of the Holocene, which did not cause such profound destabilization. This clear distinction enables quantitative and qualitative comparisons between the Holocene and Anthropocene epochs, as already utilized, for instance, within the planetary boundaries framework. As the Anthropocene Earth system transformation is systemic, political responses also need be systemic, rather than ad hoc. A unified Anthropocene epoch would help facilitate systematic, actionable climate and environmental policies. By contrast, alternative, extended interpretations of the Anthropocene are used to reflect accumulated human environmental impacts over many millennia. These broader interpretations portray the totality of anthropogenic change but obscure the quantitatively established departure from Holocene conditions. Applying a consistent Anthropocene epoch definition will improve its utility to science, scholarship and policy. The Anthropocene is a term applied across geological, environmental and social sciences, and the humanities and arts. This Perspective explores various applications of the term and discusses how a consistent definition could support transdisciplinary efforts to address modern environmental challenges.

The aging of global concrete infrastructure has precipitated an urgent demand for efficient repair and rehabilitation strategies. Alkali-activated materials (AAMs) have emerged as a promising alternative to Ordinary Portland Cement (OPC) binders. However, the effectiveness of repaired systems is predominantly governed by the integrity of the new-to-old interface between new repair materials and old existing concrete, which remains the most vulnerable region in repaired composites. This review systematically examines recent progress and advances in the use of AAMs as sustainable repair binders. Interfacial bonding behavior is systematically examined at multiple scales, from macroscopic bonding strength and failure modes to microscale products, microstructures and micro-mechanical properties. Reasons for vulnerability mechanisms of the new-to-old interface are discussed and the Overlay Transition Zone (OTZ) is quantitatively defined based on products evolution and quantitative phase distribution. Strategies to enhance interfacial performance are summarized from the aspects of AAMs mix optimization and substrate surface treatments. Furthermore, the durability of composites repaired using AAMs, including to high temperatures and chloride attack, is reviewed to examine their long-term service life. Finally, comparative analyses of costs and embodied carbon are used to highlight the potential of AAMs as eco-friendly and cost-effective solutions for sustainable infrastructure rehabilitation. Future research still requires application-oriented and intelligent design of AAMs, long-term and large-scale performance evaluation, and use of advanced interfacial characterization techniques to allow assessment and optimization of the bonding performance of AAMs.

In the 21st century tsunamis have claimed the lives of over 250,000 individuals, and have caused extensive damage to vulnerable coastal ecosystems. This vulnerability continues to increase in many areas as human activity further degrades the coastal forests that once provided a degree of protection against storms and tsunamis, collectively known as high energy marine inundation events. This work presents a case study of the design and implementation of a forested bioshield established to protect a vulnerable wetland on Maui's south east coast. Although subject to coastal inundation, this ecosystem provides high quality habitat for numerous endangered species. Anthropogenic modifications around the wetlands, particularly the loss of the protective forest, have made this ecosystem vulnerable to future inundation events. Establishing an effective bioshield requires in-depth knowledge of both the frequency and intensity of inundation events, as well as effective tree species selection and their proper configuration within the bioshield. Here, we present palynological and archaeobotanical data from the studied wetlands, and combine this with local paleotsunami data, previously published data on forested bioshields, and traditional ecological knowledge to design, optimize and install an 8,000 m2 forested bioshield, and review the wider benefits and limitations of this bioshield approach.

Geopolymer, a waste-based material with excellent thermal, mechanical, or chemical properties and low embodied carbon, can serve as an effective repair material for structural rehabilitation. In this work, three kinds of cementitious substrates with varying surface moisture conditions were prepared before applying fresh geopolymer repair material, i.e., dry (C-D), ambient (C-A) and saturated (C-S). Interfacial flexural-tensile strength, direct tensile strength and slant shear strength were tested to evaluate the interfacial bonding strength of the geopolymer-cement composites, and the bonding mechanism was revealed through X-ray Diffraction (XRD) and Back Scattered Electron (BSE)-Energy Dispersive Spectrometer (EDS) methods. Interfacial bonding strength results indicate that having a dry substrate surface is disadvantageous for relatively long-term bonding performance. The interfacial product was found to be geopolymer gel from XRD and EDS analysis, with the Ca content of the interfacial products increasing with a rise in surface moisture. The "Overlay transition zone (OTZ)" was defined based on the wall effect of unreacted particles packing of repairing material, and its thickness was found to be ca. 30 mu m. The OTZ thickness of samples with an initially dry concrete surface was greater than that with ambient moisture and water-saturated samples, and there were more unreacted particles within its OTZ. Finally, the complex effects of varying surface moisture were explained by the integrated analysis of interfacial products and microstructures.

Remediating metal-contaminated sites, particularly those impacted by the extraction or processing of critical raw materials (CRMs), poses significant environmental and health challenges. This topic has typically been approached from either a physicochemical or a biological perspective, depending on the disciplinary focus. The present review seeks to bridge that gap by integrating both approaches into a unified and comprehensive framework, exploring their interconnections and highlighting the insights that emerge from their synthesis. It describes current advances in both methods groups for the treatment of metal-containing wastes, focusing on the removal of toxic metal(loid)s, and the recovery of CRMs within the framework of the circular economy. Physicochemical techniques play a crucial role in waste decontamination, while biological methods may offer environmentally sustainable alternatives for mitigating metal pollution. Microbial strategies are particularly advantageous due to their high specificity and effectiveness even at low contaminant concentrations, while also facilitating site restoration with minimal ecological damage. Integrating biological and physicochemical treatments may significantly enhance remediation performance, for more efficient and sustainable solutions. In particular, "treatment trains" or sequential treatment approaches combine multiple remediation methods to enhance efficiency while enabling recovery and reuse of valuable metals. Successful implementation of these strategies requires the optimization of treatment conditions and the integration of green remediation practices into large-scale applications. This review highlights the need for more comprehensive and in-depth studies (including field-scale applications) to address critical knowledge gaps and to further develop these potentially cost-effective and more sustainable methods for extracting valuable metals from mining waste.

Higher activity liquid wastes pose a significant management challenge at nuclear sites, and there is a strong drive to develop cost-effective (and more sustainable) waste treatment solutions that can remove radioactive and other contaminants from these liquid radioactive wastes (LRW) prior to their discharge or final storage/disposal. Here, results are presented from an on-site trial of a coupled non-thermal plasma / sorption-based LRW treatment system at the "Dibrova" Object in the Chornobyl Exclusion Zone. Over 2m(3) of Cs-137 and Sr-90 contaminated LRW from settling tanks used for the holding of tailings and drain water from Chornobyl Building N degrees 5 and deactivation solutions (used in the liquidation efforts following the 1986 Chornobyl disaster) were treated. The coupled treatment process removed greater than 90 % of Cs-137 and Sr-90 from the most contaminated liquids (containing 75 Bq/kg (Cs-137) and 195 Bq/kg (Sr-90)), generating a low mass (<100g ) iron-rich solid residue suitable for onward storage/disposal. Treatment efficiencies for other waste components (e.g. nitrites, phosphates and COD) were equivalent to or exceeded those previously reported for treatment of environmental liquid wastes by similar Advanced Oxidation Processes. The power requirements of the system (due to the pulsed nature of the plasma generated) were relatively low, at 10 kWh, for a LRW treatment rate of 15 - 20 L/h. The system can be operated remotely in autonomous mode, and its modular, easily transportable nature means that the process can be readily adapted for various on-site treatment scenarios.

This is the Executive Summary of a report produced by the membership of the Anthropocene Working Group as part of a submission to the Subcommission on Quaternary Stratigraphy to seek formalisation of the Anthropocene as an epoch of geological time. It summarises the content of two reports and their associated appendices which provide a background to: the history of usage of the term Anthropocene, when the proposed epoch started, the characterisation of the Anthropocene geological deposits and their stratigraphic value, the recognition of the Anthropocene in different sedimentary environments, the rank and duration of the Anthropocene, the proposed Global boundary Stratigraphic Section and Point and supporting Standard Auxiliary Boundary Sections.

Plastic pollution poses a substantial environmental challenge on global scale. Recently, tyre and road wear particles (TRWPs) have been recognized as a source of microplastic pollution to the freshwater environment. Whilst there is a growing concern regarding the potential environmental effects of microplastics, TRWPs are especially concerning because of the additives they have. These additives are utilised in the manufacturing of tyres; persist in the final product; become environmentally available; and may pose significant threats to an ecosystem. A current issue is the identification of specific constituents of TRWPs responsible for these threats. A comprehensive review of the existing literature is presented focusing on the physical and chemical characteristics of TRWPs with the aim to identify suitable marker(s). Wear particles derived from tyre tread possess distinctive a sausage shape that is exclusive to TRWPs. A range of chemical additives linked to tyres have been employed to quantify TRWPs, overlooking other potential sources such as brake wear and exhaust emissions. We found that significant amounts of 6PPD is used for the formulation of tyres, which is why 6PPD, and a comparatively stable transformation product 6PPD-quinone, could be used for the identification of TRWPs. We recommend that sampling and analysis methods be thoroughly documented to enhance the reproducibility.

AbstractMultiple expressions of climate change, in particular warming‐induced reductions in the type, extent and thickness of sea ice, are opening access and providing new viable development opportunities in high‐latitude regions. Coastal margins are facing these challenges, but the vulnerability of species and ecosystems to the effects of fuel contamination associated with increased maritime traffic is largely unknown. Here, we show that low concentrations of the water‐accommodated fraction of marine fuel oil, representative of a dilute fuel oil spill, can alter functionally important aspects of the behaviour of sediment‐dwelling invertebrates. We find that the response to contamination is species specific, but that the range in response among individuals is modified by increasing fuel concentrations. Our study provides evidence that species responses to novel and/or unprecedented levels of anthropogenic activity associated with the opening up of high‐latitude regions can have substantive ecological effects, even when human impacts are at, or below, commonly accepted safe thresholds. These secondary responses are often overlooked in broad‐scale environmental assessments and marine planning yet, critically, they may act as an early warning signal for impending and more pronounced ecological transitions.

This study investigated the spatio-temporal variability of microplastics (MPs) in the sediments of the River Thames (UK) catchment over 30 months (July 2019 - Dec 2021). The average MP concentration was 61 items kg-1 d.w., with fragments <1 mm being dominant and polyethylene (PE) the most common polymer. Adjacent land use influenced MP concentrations and types, with industrial sites showing particularly high levels and a prevalence of small beads and industrial polymers. MP concentrations generally decreased after higher winter flows, likely due to sediment rearrangement or winnowing. This study describes the seasonal concentrations and characteristics of MPs present in sediment from the River Thames catchment, and attempts to identify their likely origin. Further, the study provides new insights into the mobility and fate of MPs in riverine settings under varying flow conditions, which is vital given the predicted increases in flooding under various global heating scenarios.

In Hawai`i, tsunamis are often described in orally transmitted legends (mo`olelo). This study examines sedimentary evidence of a possible local submarine landslide-generated tsunami, described in a legend from the south east coast of Maui which originated between the 15th Century CE and the first arrival of Europeans in 1778 CE. Physical evidence for a tsunami, found at the Nu'u Refuge, Maui, is primarily comprised of an extensive coral clast deposit (found 8.5 m above msl and 251 m inland from the shoreline) together with waterworn cobbles which form fracture-embedded wedge clasts in a local basalt escarpment (at up to 8 m above msl). U/Th dating of the coral clasts gives a maximum tsunami deposit age of 1671 CE for the event that may have inspired the local mo`olelo. This depositional sequence is used to characterize the nature of the assumed tsunami in terms of inundation distance, maximum wave runup and minimum flow velocities. A numerical model developed using GeoClaw matches well with the physical evidence. The data and modeling presented here suggest that locallygenerated tsunamis from submarine landslides warrant further research attention as sources of destructive high energy marine inundation events.

The "Great Acceleration" beginning in the mid-20th century provides the causal mechanism of the Anthropocene, which has been proposed as a new epoch of geological time beginning in 1952 CE. Here we identify key parameters and their diagnostic palaeontological signals of the Anthropocene, including the rapid breakdown of discrete biogeographical ranges for marine and terrestrial species, rapid changes to ecologies resulting from climate change and ecological degradation, the spread of exotic foodstuffs beyond their ecological range, and the accumulation of reconfigured forest materials such as medium density fibreboard (MDF) all being symptoms of the Great Acceleration. We show: 1) how Anthropocene successions in North America, South America, Africa, Oceania, Europe, and Asia can be correlated using palaeontological signatures of highly invasive species and changes to ecologies that demonstrate the growing interconnectivity of human systems; 2) how the unique depositional settings of landfills may concentrate the remains of organisms far beyond their geographical range of environmental tolerance; and 3) how a range of settings may preserve a long-lived, unique palaeontological record within post-mid-20th century deposits. Collectively these changes provide a global palaeontological signature that is distinct from all past records of deep-time biotic change, including those of the Holocene.

The Anthropocene as a prospective new, ongoing series/ epoch must be defensible against all relevant concerns. We address the seven, still-relevant challenges posed to the Anthropocene Working Group by the Chair, International Commission on Stratigraphy (ICS), in 2014. (1) Concept or reality? The Anthropocene possesses a substantial, sharply distinctive stratigraphic record recognisable through many proxy signals from the mid-20th century onwards; (2) GSSP or GSSA? The Anthropocene can be defined by GSSP and correlated globally; (3) Past or future? The Anthropocene unquestionably represents geological time, its transformations having already moved the Earth System beyond Holocene norms towards an irreversible future trajectory; (4) Utility? The Anthropocenes' distinctive material content allows useful delineation on geological sections/maps; (5) Indelibility? Many of the Anthropocenes' transformative effects cannot be subsequently effaced or overprinted; (6) Fit within the Geological Time Scale (GTS)? The Anthropocene represents a unique, youngest, interval in Earth history and strata of profound significance; What is its value? The chronostratigraphic Anthropocene has conceptual usefulness even informally, but would then lack the clarity, stability and recognition that formalization provides. Without its formalization, the GTS would longer accurately reflect Earth history, diminishing relevance of geological science for analysis of ongoing planetary change.

This part of the Anthropocene Working Group (AWG) submission proposes that the base of the Anthropocene should be defined as series/epoch, terminating the Holocene Series/Epoch with a single Crawfordian stage/age using a Global boundary Stratotype Section and Point (GSSP) in an annually varved Crawford Lake core, Ontario, Canada, defined at 17.5 cm in core CRA23-BC-1F-B at the base of the dark lamina in a varve deposited in 1952 CE, at the level where the primary marker shows a rapid increase in 239+240Pu concentrations (coinciding with a globally recognisable, isochronous signal of the first above-ground thermonuclear tests). Secondary markers, determined in precisely correlated core closely adjacent to the proposed GSSP host, include a marked increase in 14C values and in spheroidal carbonaceous particles (SCPs), increased heavy metal concentrations, a decline in δ15N values, a marked change in phytoplankton assemblages and declines in elm (Ulmus) pollen and in non-arboreal pollen. The submission also provides descriptions of three proposed Standard Auxiliary Boundary Stratotypes (SABSs), in cores extracted from marine anoxic sediments of Beppu Bay (Japan), in Sihailongwan Maar Lake (China) and in the Śnieżka Peatland (Poland) and eight reference sections located in cores extracted from marine anoxic sediments in the Baltic Sea, from coral bioherms off Australia and in the Gulf of Mexico, from an Antarctic ice core, from San Francisco Estuary and nearby lake (USA), in a speleothem from northern Italy and a section in urban anthropogenic deposits in Austria. This ubiquity of signals verifies that the Anthropocene can be widely delineated as a sharply distinctive chronostratigraphic unit in diverse terrestrial and marine depositional environments, and reflects a major Earth System change that will have geologically lasting consequences.

The performance of contaminated site management in terms of its sustainability can be inherently uncertain, considering that this performance depends not only on individual site characteristics and variability, but also on integrated (and potentially long-term) environmental, social, economic and technical impacts. The present study proposes a combination weights-based TOPSIS model (Technique for Order Preference by Similarity to Ideal Solution), following a multi-criteria decision analysis (MCDA) approach, to quantitatively analyze the most influential measures and indices over the entire life cycle of contaminated site management (from site investigation to land reuse) in China. Results indicate that the sustainability performance of different sites varies widely due to differences in the best management practices (BMPs) implemented. Environmental dimensions in strategy design and remediation implementation processes contribute most to the overall sustainability performance when whole life-cycle management is considered, with social dimensions relatively under-emphasised. Based on a sensitivity analysis of the TOPSIS method, random variations of indices' weights did not result in significant alteration of the modelled sustainability performance of the evaluated sites, which indicates that the method provides a relatively robust approach. The MCDA approach developed enables stakeholders to adopt optimal BMPs for risk control and to enhance sustainability performance in contaminated site management, covering the whole life cycle of site remediation and redevelopment, although further work is required to determine its international applicability.

Corn cob ash (CCA) is a kind of agricultural solid waste produced by the burning of corn cob after removal of the corn kernels, which requires sustainable disposal routes. In order to utilize CCA and understand its role in geopolymer, CCA-amended geopolymer grout was prepared and effects of CCA on geopolymerization process and products were investigated in this study. With CCA included, there was less C-S-H/C-A-S-H gel and more calcite, also portlandite generated. Two extra weak exothermic peaks were observed for CCA-amended geopolymer with optimal mix proportion (CCA20A6), probably due to additional reactions induced by CCA, also verified by the disappearance of syngenite. Following application of CCA20A6 to repair cracks, compressive strength and ultrasonic pulse velocity (UPV) of the repaired composites were improved, and no cracking was observed at the bonding interface, verifying successful repair. Based on life cycle assessment in cradle-to-site boundary, the total embodied energy (EE) and global warming potential (GWP) of CCA20A6 were decreased by 7.8% and 15.5%, respectively, compared to non-CCA geopolymer. Considering performance of samples, the addition of CCA would lead to an about 30% decrease in economic index. In conclusion, CCA could play a role as a precursor due to soluble Si, Al, and Ca components, and also as an activator due to its intrinsic alkalinity, which makes CCA-amended geopolymer to be an eco-friendly grouting material with better performance as well as lower costs.