Marine silicate alteration is tightly linked to carbon burial over geological time scales, especially in continental margins known as ‘hotspot’ due to active organic carbon-driven diagenetic processes. Volcanic materials are one of the most reactive silicate groups, which plays an important role in sedimentary Si processes in continental margins. Since the Last Glacial Maximum, continental margins have undergone strong sediment regime shift, including sediment source changes, due to sea level rise. However, how marine silicate alterations respond to such sediment regime shifts remain largely unexplored. This study uses a 155-meter-long sediment core (IODP Exp. 375 U1518) from the Hikurangi margin, eastern New Zealand, one of the most representative sites in the subduction zone that are enriched with volcanic materials and meanwhile suffers from drastic sea level rise over a hundred of meters in the past 20,000 years. A tailored Si isotope-based sequential chemical leaching protocol in combination with porewater chemistry and geochemical analysis enable us to interrogate the sediment core in great details and uncover sedimentary Si mass balance by constraining various Si endmembers and major Si geochemical processes. Our results show that the δ30Si values of Si endmembers can vary by 1‰ within 1.5–155.7 mbsf due to sediment source changes and early diagenetic modifications. This suggests that conventionally fixed δ30Si value of a single Si endmember through one sediment core may result in large uncertainty in constraining sedimentary Si processes. A potential organic-bounded Si phase with a δ30Si value of −0.19 ± 0.21‰ was also observed in this study. Simulations of a reactive-transport model further reveal enhanced clay mineral dissolution in the shallow Holocene sediments, leading to rapid porewater dissolved Si (DSi) increase and δ30SiDSi value decrease. Compared with the Pleistocene sediments, these changes directly elevate DSi diffusive flux by an order of magnitude with a lower δ30Si value toward seafloor. Meanwhile, slow incongruent volcanic material dissolution in the deep Pleistocene sediments drives the gentle increase of DSi concentrations and δ30SiDSi values, from 541 μmol/L and + 0.24 ± 0.16‰ at 37.10 mbsf to 686 μmol/L and +0.94 ± 0.23‰ at 155.70 mbsf, respectively. High vs. low silicate alteration rates between shallow and deep sediments generates a large DSi concentration gradient and downward diffusion. We propose that it is necessary to include Si phase-based isotope analysis for better constraining marine silicate alterations and its mass balance, particularly for those environments subjecting to sediment source changes. Our findings also highlight that simply attributing decrease of DSi concentration to authigenic clay precipitation (reverse weathering) may cause an overestimation of its role in regulating marine carbon cycle during glacial-interglacial transgressions.

Hadal trenches have been taken as hotspots for organic carbon burial and microbial activity in the deep-sea settings. In this study, water-extractable (WEOM) and porewater dissolved organic matter (PWOM) were analyzed from two sites in the Mariana Trench-MT04 (clay-dominated) and MT05 (laminated diatom mat, LDM sediments)-to evaluate the influence of mineral association on dissolved organic matter composition, optical characteristics, and stable carbon isotopic signatures. Compared to the LDM core, WEOM in the clay-dominated core shows higher SUVA(254), humification index (HIX), and A(253)/A(203) values, but the fluorescence index (FI) is lower. These optical characteristics indicate higher aromaticity, a greater degree of humification and lower bioavailability of WEOM. Such patterns suggest that clay minerals selectively adsorb and occlude aromatic- and carboxyl-rich dissolved organic matter. This mineral association reduces microbial accessibility and enhances long-term preservation. Comparison between WEOM and PWOM further reveals distinct compositional and functional differences within the sedimentary organic carbon pool. WEOM is tightly associated with mineral surfaces, enriched in aromatic and humified components, and exhibits stronger stability, whereas PWOM contains more protein-like and labile constituents. The decreasing trend in delta C-13 (delta C-13 of sediment total organic carbon > delta C-13 of WEOM > delta C-13 of PWOM) indicates that selective microbial degradation and mineral protection jointly regulate dissolved organic matter transformation pathways. Therefore, WEOM represents a mineral-associated, relatively stable carbon reservoir that plays a crucial role in long-term organic carbon preservation in the deep-sea environment.

Plutonium (Pu) isotopes are anthropogenic radionuclides characterized by highly chemical toxicity and radiotoxicity that persist in the atmosphere. Monitoring atmospheric Pu concentration is important for understanding its environmental characteristic and source identification. In this study, the activity concentrations of 239,240Pu and 240Pu/239Pu atom ratios in PM2.5, PM10, and total suspended particulate (TSP) collected in 2022 in Beijing were determined. The determined 240Pu/239Pu atom ratios were in the range of 0.136-0.222, with the average value of 0.176 ± 0.005, which was in accordance with the global fallout. The measured 239,240Pu activity concentrations in PM2.5, PM10, and TSP were in the range of 3.89 × 10-6-1.11 × 10-3 Bq/g, 1.04 × 10-5-1.02 × 10-3 Bq/g, and 2.88 × 10-5-9.92 × 10-4 Bq/g, respectively. The seasonal variation trend affected by monsoon climate was observed, which was characterized by higher value in spring, followed by the winter, and lower value in autumn. Meanwhile, the particle size distribution of Pu isotopes was discussed. About 50% of Pu isotopes were enriched in fine particles (2-2.5 μm), only ∼4.8% in the fraction of 2.5-10 μm, and ∼45.2% in 10-100 μm range. Fine particles (2-2.5 μm) are the primary carrier of atmospheric Pu in Beijing. By comparing 239,240Pu concentrations in TSP samples and in the surface soil, the long-range transport of resuspended soil was considered as the main source of Pu during sandstorm, and the local soil resuspension was regarded as the main source of Pu on non-sandstorm days.

Sedimentary biogenic silica (bSi) is a primary sink of oceanic silicon (Si), and its quantification is essential for constraining the marine Si budget. The traditional alkaline leaching method estimates bSi contents by extrapolating a regression of Si leachates at 2, 3, and 5 h, but this approach is biased by lithogenic Si (LSi) dissolution. We analyzed 59 marine sediment samples (0.2 to 57.0 wt% bSi) and used Si isotopes to re-assess this method. Samples with moderate bSi contents (5-20 wt%) show a marked decline in dissolution rates after 3-5 h of leaching. Si isotopes of the leachates reveal that the decline reflects either a shift from dominant bSi to LSi phase or changes in bSi species through time. Sediments with <5 wt% or > 20 wt% bSi display a stable Si dissolution rate throughout 8 h, likely due to unchanged dominant Si phases of lithogenic or biogenic Si. Additionally, we re-assessed the brucite co-precipitation method (MAGIC) for porewater dissolved Si (dSi) recovery. Mg/Si molar ratios <100 yield dSi recovery <90%, resulting in large isotope fractionation. Hence, an Mg/Si ratio of >= 300 is recommended to guarantee full recovery, and H2O2 pretreatment is necessary to eliminate matrix effects induced by high Fe, Mn and DOC concentrations. Our findings imply that the traditional leaching method likely underestimates current bSi contents, especially in clay or/and organic-rich sediments with moderate bSi contents.

There has been a long-standing paradox in oceanic phosphorus (P) cycling in the ocean: high alkaline phosphatase activity (APA) persists in deep waters despite replete dissolved inorganic phosphorus (DIP), and active microbial regulatory mechanisms driving this pattern remain largely untested in the carbon-limited hadal zone. Here, we test the hypothesis that the observed elevated levels of deep-ocean APA is driven by microbial carbon demand, via full-depth water column analyses of dissolved organic phosphorus (DOP) and DIP in the Challenger Deep (Mariana Trench), combined with laboratory-based in situ-simulated high-pressure incubation experiments. We reveal two distinct phosphorus-alkaline phosphatase activity (P-APA) regulatory regimes: P-limitation-driven extreme APA in P-depleted surface waters, and sustained, elevated APA in P-replete, carbon-starved deep waters. Metabolically active alkaline phosphatase (AP)-producing taxa, most notably the SAR11 clade, were detectable throughout the full water column. Path analysis was used to evaluate the consistency of the observed data with a hypothesized causal framework linking active microbial communities, APA kinetics, and coupled phosphorus-carbon (P-C) cycling, with the model explaining 82.3% of the variance in dissolved organic carbon and 75.4% of the variance in DIP in the water column. We propose and validate a “piggyback” strategy whereby deep-sea microbes express AP to acquire carbon from DOP, offering a previously untested, potential mechanistic explanation for the long-standing deep APA paradox, while revealing a microbially mediated P-C coupling pathway that may represent a breakaway of deep-ocean carbon sequestration pathway.

To tackle the environmental challenges associated with industrial oily wastewater discharges and recurrent marine oil spill incidents, developing high-efficiency oil-water separation technologies represents a pressing environmental challenge. This research presents a novel design approach comprising the deposition of a stable SiO2 anchoring layer followed by the fabrication of a PDA/CS crosslinked coating, thereby achieving successful construction of a superhydrophilic/underwater superoleophobic (SH/UWSO) coating on stainless steel meshes (SSM). In the first step, SiO2 microspheres were deposited via vapor deposition to create a micro-rough surface architecture. Subsequently, a dopamine/chitosan (DA/CS) reaction solution was introduced to form a Polydopamine/chitosan (PDA/CS) coating, yielding a SiO2@PDA/CS-SSM separation membrane. The resulting membrane exhibited separation efficiencies surpassing 99% for various oil-water mixtures, achieving a flux of 1.24 & times; 105 L & centerdot;m-2 & centerdot;h-1 in petroleum ether systems. Notably, the membrane maintained high efficiency and structural stability even after 25 separation cycles, immersion in strong acid and base solutions for 72 h, and 100 abrasion tests. The rational design of the anchoring and crosslinking layers endows SiO2@PDA/CS-SSM with high efficiency and stability, making it an effective oil-water separation material.

Though volcanogenic massive sulfide (VMS) deposits are major global sources of indium (In), the physicochemical mechanisms and key factors controlling its significant enrichment remain poorly understood. To address the issue, this study investigates the Tiemurt VMS Pb-Zn-Cu deposit, utilizing detailed petrography, in-situ LA-ICP-MS analysis, and thermodynamic modeling to reveal the In enrichment mechanisms in VMS deposits. Petrographic observations identified two distinct generations of sphalerite corresponding to different mineralization stages. The early-stage sphalerite (Sp1) is euhedral-subhedral, associated with pyrite, and displays darker colors (red to brown), whereas the late-stage sphalerite (Sp2) is anhedral, intimately intergrown with chalcopyrite, and shows lighter colors (mainly yellow). The trace element results demonstrate that Sp1 has a significantly higher In content (average 317 ppm) than Sp2 (average 220 ppm). Additionally, In concentrations positively correlate with Fe contents. Because Fe is the primary chromophore that darkens sphalerite, this strong coupled enrichment mechanism allows macroscopic sphalerite color (red > brown > yellow) to serve as a reliable indicator for In concentration. Crystallization temperatures calculated using the GGIMFis thermometer range from 344 to 382 °C for Sp1 and 312 to 355 °C for Sp2, indicating a cooling trend during fluid evolution. Thermodynamic modeling data showed that in the early-stage hydrothermal fluids (≥360 °C), Zn2+ preferentially complexes with Cl−, leaving InCl2+ or In3+ as unstable species, and In efficiently precipitates into Sp1 under the environment of log fO2 = −32 to −26 and pH = 6–8. As the fluids cool at ~340 °C, weakened Zn2+ competition allows In3+ to form stable InCl3, and In precipitates into Sp2 under the conditions of log fO2 = −42 to −32 and pH = 5.5–11. We therefore conclude that the key factor controlling the difference in In content between Sp1 and Sp2 is the precipitation mechanism rather than migration capacity. This may be different from the In enrichment mechanism associated with magmatic hydrothermal systems, where In is mainly present as InCl3 complexes with strong migration capacity. These new findings enable us to understand how the physicochemical conditions of fluids control the enrichment of In in VMS deposits, and also highlight that the color of sphalerite can be used to target potential In resources in PbZn deposits.

Although per- and polyfluoroalkyl substances (PFAS) are widespread in global ecosystems, their presence in the hadal zone, particularly that of novel compounds, remains unexplored. In this study, 15 PFAS were detected in amphipods from the Mariana, Mussau, and New Britain Trenches (ranging from 0.4-37.5 ng g-1 dry weight), whereas all seawater and sediment samples fell below the detection limit. We quantified organism-water partitioning, analyzed structural and concentration similarity via COSMO-RS, applied neural networks to predict bioaccumulation, and prioritized PFAS risks using a persistence-bioaccumulation-toxicity framework. Short-chain novel PFAS (e.g., PFBA and PFPeA) formed the largest share of total PFAS loads (up to 4.2 ng g-1 dw) but contributed minimally to risk. In contrast, long-chain PFAS (PFTrDA and PFUnDA), though less abundant, exhibited substantially higher risk potential. The novel compound F-53B was detected exclusively in Mariana amphipods. Overall, the accumulation patterns across PFAS classes reflect the combined influence of external exposure and internal partitioning constraints. These findings demonstrate that structural modification does not inherently reduce PFAS hazards and highlight the necessity of including hadal organisms in global chemical risk evaluation.

Understanding the mechanisms driving species assembly along elevational gradients in mountains is crucial for biodiversity conservation. However, no consensus has yet been reached on how these mechanisms work. This knowledge gap is particularly pronounced in biodiversity-rich subtropical karst mountains. Integrating multidimensional biodiversity information into research in karst systems will provide new insights into community assembly. Thus, we explored multidimensional forest diversity along an elevational gradient at Jinfo mountain, a karst mountain site, assessing the relative importance of distinct ecological processes in shaping patterns of community diversity and structure. Our results show that different dimensional diversities exhibit similar elevational patterns, with higher diversity observed at low-to-mid elevations than at high elevations. The multidimensional diversity and structure were primarily controlled by climate stress and topographic filtering and were further modulated by soil nutrient limitation and interspecific competition. However, the explanatory weights of these ecological processes were inconsistent among the different dimensions of diversity. The phylogenetic structure was clustered at low and middle elevations, with over-dispersion at high elevations. This indicates that community assembly shifted from being dominated by environmental filtering to being dominated by competitive exclusion as elevation increased. In conclusion, our results demonstrate that combining multidimensional diversity and multiple ecological processes related to community assembly can enhance the understanding of diversity patterns along elevational gradients and the underlying mechanisms maintaining them in subtropical karst mountains.

The elemental exchange fluxes at the sediment–water interface play a crucial role in Earth's climate regulation, environmental change, and ecosystem dynamics. Accurate in situ measurements of these fluxes depend heavily on the performance of marine incubation devices, particularly their ability to achieve full mixing without causing sediment resuspension. This study presents a novel parameter calibration method for a marine in situ incubation device using a combination of computational fluid dynamics (CFD) simulations and laboratory experiments. The influence of the stirring paddle’s rotational speed on flow field distribution, complete mixing time, and sediment resus-pension was systematically analyzed. The CFD simulation results were validated against existing device data and actual experimental measurements. The deviation in complete mixing time between simulation and experiment was within −9.23% to 9.25% for 20 cm of sediment and −9.4% to 9.1% for 15 cm. The resuspension tests determined that optimal mixing without sediment disturbance occurs at rotational speeds of 25 r/min and 35 r/min for the two sediment depths, respectively. Further analysis showed that the stirring paddle effectively creates a uniform flow field within the chamber. This CFD-based calibration method provides a reliable approach to parameter tuning for various in situ devices by adjusting boundary conditions, offering a scientific foundation for device design and deployment, and introducing a new framework for future calibration efforts.

Nitrate (NO3-) is a crucial component of atmospheric pollutants, and understanding its sources and formation mechanisms holds significant importance for air pollution control. In this study, stable isotope techniques and Bayesian Mixing Models (Mix SIAR) were applied to analyze the primary sources and formation processes of NO3- in PM2.5 and PM10 in Beijing in 2022. The results indicate that the contribution of vehicle exhaust, coal combustion, biomass burning, and soil emissions to NO3- in PM2.5 were 33.9%, 20.5%, 29.8%, and 15.9%, respectively, while for PM10, the contributions were 30.6%, 21.6%, 29.9%, and 17.9% respectively. An analysis of δ18O-NO3- values indicated that the contribution of N2O5 hydrolysis to NO3- in PM2.5 and PM10 over the year was 64.0% and 75.6%, respectively, highlighting its predominant role in nitrate formation. Nevertheless, the gas-phase reaction of NO2 with ·OH radicals was notably more pronounced in summer. Compared to PM10, the gas-phase reaction of NO2 with ·OH radicals contributes more to NO3- in PM2.5. These results offer a vital foundation for further research into the sources and formation mechanisms of atmospheric NO3- and provide scientific support for measures to prevent and control air pollution.

Currently, there is an increasing demand for simple, rapid, and accurate analytical methods for analyzing 236U and 236U/238U isotope ratios in the swipe, nuclear accident, or environmental samples. In response to the complexities inherent in traditional methodologies and the high uncertainty associated with analytical techniques, we developed a rapid method that integrates alkali fusion with thermal ionization mass spectrometry. This method addresses the shortcomings of traditional methods, especially the issue of sample pretreatment efficiency. The efficacy and practicality of the developed method are demonstrated by eliminating the ashing process, reducing evaporation, and direct purification. After parameter optimization, the uranium recovery exceeded 80 %, and the pretreatment process was completed within 7 h for a batch of samples. We tested the method's stability and applicability by analyzing the certified and IAEA reference materials and found that it was suitable for various environmental samples. The measurement of the 236U/238U isotope ratio and 236U concentration were achieved using the developed thermal ionization mass spectrometry method. The method was validated using IRMM 184 with an accuracy of 0.11 %. The developed pretreatment and instrumental method were applied to IAEA reference materials, and the measured 236U/238U isotope ratios and 236U concentrations were consistent with the reported values. This method can be directly used in scenarios requiring rapid analysis and high-precision measurement of uranium isotopes.

Ecologists have paid considerable attention to the adaptation and distribution of urban landscape species in China amid rapid urbanization and climate change, given the essential role of urban species in human activities, urban planning, and sustainable development. However, existing studies primarily concentrate on the effects of climate change on the distribution of native species, creating a research gap regarding alien species. We compiled 5261 distribution data points for 538 alien woody landscape species (WLS) (non-native to China) from 179 cities with populations over one million in China and utilized the MaxEnt model to assess the future distribution and migration patterns of 27 most commonly introduced evergreen broad-leaved, evergreen coniferous, and deciduous broad-leaved species under present, 2041-2060, and 2081-2100 periods according to the Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 climate scenarios. The results indicated that deciduous broad-leaved species were widely distributed in Southwest China, East China, Central China and North China regions, had a broad climate niche and greater adaptability to climate change, while the suitable area of evergreen species were expected to be lower than that of the present stage after 2100. The preserved suitable areas of evergreen species were mainly concentrated in the East China and Central China regions, and the lost suitable areas of evergreen coniferous species were in South China and southern East China regions. We also noted that human activities were the most important factor influencing the species distribution, not only in terms of the differences in suitable areas, but also the spatial diversity patterns. Our study revealed the future distribution patterns of three vegetation types and highlighted the importance of preventing the transformation of alien WLS into invasive species, which can provide valuable guidance for urban planning and development.

The deep oceans are environments of complex carbon dynamics that have the potential to significantly impact the global carbon cycle. However, the role of hadal zones, particularly hadal trenches (water depth > 6 km), in the oceanic dissolved organic carbon (DOC) cycle is not thoroughly investigated. Here we report distinct DOC signatures in the Japan Trench bottom water. We find that up to 34

Hadal trenches have recently been recognized as hotspots for organic carbon burial and degradation in the deep sea owing to its distinctive “funnel‐shaped” topography and frequent tectonic activity. In this study, we analyzed dissolved organic carbon (DOC) concentration, optical properties, and molecular compositions of water‐extractable organic matter (WEOM) in the sediment samples collected along two transects spanning diverse marine environments of the New Britain Trench (NBT) area. A significant positive correlation between DOC concentrations and total organic carbon (TOC) contents in sediments emphasizes the crucial role of organic matter (OM) supply for DOC production in the hadal environment. In addition, the optical parameters (e.g., fluorescence index, a 350 /DOC) suggest remarkable influences of terrestrial OM on the composition of dissolved organic matter (DOM) in the NBT sediments. Indeed, the correlations between the stable carbon isotopes of sedimentary TOC (δ 13 C) and related optical parameters (SUVA 254 , a 350 /DOC, S R and terrestrial humic‐like) indicate that microbial degradation of terrestrial OM has an important impact on the sedimentary DOM. Moreover, analysis of DOM molecular compositions showed increased aromaticity and double bond equivalents double bond equivalent in the western landward core and two axis cores, also suggesting enhanced microbial degradation of terrestrial OM. The input of terrestrial OM into the NBT has led to production of aromatic, refractory, and high molecular weight DOM. Our findings have implications for understanding the fate of terrestrial OM in the deep ocean.

A rapid method has been developed for determining ultra-low level Pu isotopes in atmospheric particulate matter samples using SF-ICP-MS and TEVA resin. The Pu purification, ashing conditions and microwave digestion, were optimized to achieve high decontamination factor of U (4.1 × 104) and stably high Pu recovery (80–90

Recent global radiological incidents have heightened attention to environmental radioactivity. Although analytical methods for anthropogenic radionuclides in environmental samples and background research are relatively well-established on a global scale, systematic research data are still lacking in the Northwest China region. This region is not only affected by global fallout caused by nuclear weapons tests in the last century, but also the regional fallout -the Lop Nor nuclear test site, China's only nuclear testing base. The various sources, complicated climate and terrain results in the unique distribution of radionuclides. Therefore, systematically summarizing the spatial distribution characteristics of artificial radionuclides in the northwest region serves as a scientific foundation for assessing the environmental risks associated with historical nuclear test legacies. It also represents a critical component in building a global nuclear safety monitoring network. Simultaneously, it provides essential data support for regional ecological environmental protection and the development of green industries. This study reviews anthropogenic radionuclide distribution in Northwest China's environment, highlighting uneven spatial coverage, incomplete nuclide inclusion, and insufficient databases. The paper proposes future directions for systematic and long-term comprehensive research, emphasizing the need to strengthen the investigation of the links between artificial radionuclides and ecological effects as well as health risks. This paper summarizes research to enhance monitoring and improve anthropogenic radionuclide background data, offering a scientific basis for policy-making and environmental protection. The review presented in this paper offers an important reference for further exploring solutions to environmental radioactivity issues in Northwest China.

As the concept of integrated diagnosis and treatment gains increasing prominence, the utilization of radiopharmaceuticals in personalized medicine has garnered unprecedented attention. However, the production of these radiopharmaceuticals continues to encounter numerous technical challenges. It plays an important role in improving the efficiency and convenience of nuclear medicine services and can quickly and conveniently provide the required radioactive isotopes to meet the needs of integrated clinical diagnosis and treatment while reducing dependence on external supplies and improving safety and the economy. At present, commonly used medical radioactive isotope generators include 99Mo/99mTc, 68Ge/68Ga, 90Sr/90Y, 188W/188Re, etc. This article reviews the latest research progress on three main medical radioactive isotope generators of 99Mo/99mTc, 68Ge/68Ga, and 90Sr/90Y. It also evaluates the highly anticipated new 44Ti/44Sc generator and proposes research prospects for current medical radioactive isotope generators, providing exploration directions for the future development of nuclear medicine.