Marine pollution bulletin最新文献

Coastal ocean alkalinity enhancement (OAE) is a promising ocean-based carbon dioxide removal (CDR) approach for mitigating climate change and counteracting ocean acidification. However, uncertainties persist regarding the efficacy and environmental safety of alkaline materials under realistic coastal conditions. This study comparatively investigated the CO₂ sequestration potential, geochemical processes, and environmental impacts of four alkaline materials-natural silicates (olivine, basalt) and industrial byproducts (fly ash, steel slag)-through laboratory incubations with natural seawater (filtered and unfiltered) and in situ deployments off the East China Sea. Over 31-day incubations, basalt induced negligible alkalinity release, while olivine showed limited alkalinity enhancement (12 μmol/kg/day) compared to theoretical estimation, projecting a CO₂ sequestration rate of 0.57 ± 0.06 Tg/month for a hypothetical coastal deployment in China. Notably, fly ash exhibited faster alkalinity release (30 μmol/kg/day) and the highest projected CO₂ uptake (1.24 ± 0.05 Tg/month). In contrast, steel slag caused rapid pH increase and alkalinity consumption via secondary carbonate precipitation, representing a distinct carbon sequestration pathway. Heavy metal pollution index (HPI) assessments indicated low overall contamination risks of the materials, particularly in unfiltered seawater that better resembles natural conditions, though Ni release from olivine remains a concern. Streamlined life cycle analysis (S-LCA) highlighted fly ash's advantages due to the avoidance of upstream carbon emissions (as a byproduct) and waste valorization potential, resulting in superior net CO₂ removal efficiency. This work provides critical insights into material-specific trade-offs, suggesting fly ash as a promising candidate for short-term coastal OAE deployment that balances CO₂ sequestration efficiency, manageable environmental risks, scalability, and affordability.

Mangrove restoration is fundamental to sustaining ecosystem services, yet little is known about how sediment bacterial community composition and their associated ecological functions are distributed with depth during the early stages of recovery. To fill this knowledge gap, we investigated sediments from different depths at the Baichimen restoration area (Fuding, China) one year after Kandelia obovata planting, assessing community composition, co-occurrence networks, assembly processes, and predicted functions. Our results revealed that Gammaproteobacteria, Alphaproteobacteria, Dehalococcoidia, and Anaerolineae dominated bacterial assemblages. Alpha diversity did not differ significantly among depths, whereas beta diversity distinctly separated the surface and bottom layers. Network analysis showed highest integration in the middle layer and greatest modularity in the bottom, with positive associations prevailing throughout. Among 47 keystone taxa, connectors were most abundant in the middle layer, supporting inter-module linkages and network resilience. Robustness analysis indicated that the middle layer was most resistant to minor disturbances but increasingly fragile under extensive node loss. Despite vertical divergence in community structure and network topology, the neutral community model explained over 80% of the variation in all layers, revealing a conserved dominance of stochastic assembly across sediment depths. Functional predictions identified the middle sediment as a metabolic hotspot enriched in transport, genomic plasticity, and cell-turnover pathways, emphasizing its role in substrate transformation and ecological responsiveness. Collectively, these findings reveal strong vertical heterogeneity in bacterial structure and function. Furthermore, these results underscore the critical role of middle-layer bacterial communities in driving early-stage biogeochemical processes and promoting mangrove ecosystem recovery.

Anthropogenic activities and industrial growth significantly impact the marine environment, particularly in coastal areas where human activities intersect with the ocean, often leading to anthropogenic elemental enrichments. Monitoring geochemical signals in seawater, however, is challenging logistically and analytically. As an alternative, calcitic tests of benthic foraminifera provide a nature-based, readily available tool for monitoring environmental signals. This study aimed to demonstrate the applicability of shallow-water large benthic foraminifera as recorders of fine-scale coastal elemental variability, including elements derived from anthropogenic sources. The study focuses on the short coastline of the Gulf of Aqaba-Eilat, which exhibits high diversity in both anthropogenic levels and sources, making it an ideal case study. We report whole-test (ICP-MS) element-to‑calcium ratios in living specimens of the three most common LBF taxa: miliolids (Peneroplis pertusus, soritids) and rotaliids (Amphistegina), collected seasonally from six sites representing urbanized, industrial, and nature reserve areas along the 12-km Israeli coast. Miliolids consistently exhibit elevated El/Ca values and clearer spatial and temporal trends than rotaliids, highlighting their higher sensitivity as environmental recorders. Pb, Zn, and Cd ratios distinguish polluted from relatively clean sites, while Mn enrichment likely reflects freshwater input. Rare-earth elements exhibit a north-to-south enrichment gradient, a distinct seasonal pattern, and a positive gadolinium anomaly, which may reflect anthropogenic inputs from the city of Eilat. Overall, these findings demonstrate that elemental records of miliolid taxa are very effective bioindicators of localized and seasonal geochemical signals in coastal marine environments, offering a practical, nature-based approach to monitoring anthropogenic impacts.

Climate variability and external environmental stressors within mangrove habitats could compromise the developmental physiology of the horseshoe crab, Carcinoscorpius rotundicauda. The soil bacteria, Bacillus thuringiensis was a biological strain used in pest management but became resilient under warming scenarios. This bacterium was threatening the embryogenesis and hatching survival of horseshoe crabs in Malaysia. Assays with ambient (room) temperature and incubation at 32 °C, darkness, and together with B. thuringiensis were carried out until all eggs in control groups hatched. Biomarkers like glutathione (GSH), nucleic acids, proteins, and their ratios were used to indicate stress in C. rotundicauda eggs. Results of ambient temperature indicated four embryogenesis stages where each stage coincide with deoxyribonucleic acid, ribonucleic acid, proteins, and GSH concentrations of a developing egg. While incubation (32 °C) accelerated the egg development, it also caused oxidative imbalances and metabolic stress. In addition, bacterial exposure suppressed nucleic acid and protein synthesis as both became exacerbated under the warming effects of 32 °C and darkness. Principal Component Analysis was used to distinguish the effects of treatment with positive axis loadings being direct drivers, negative axis loadings being indirect while together, indicating coordinated antioxidant and macromolecular shifts. Although, oxidative stress, nucleic acid degradation, and protein depletion underpin teratogenesis, these biochemical indicators provide sensitive early warning metrics of environmental and pathogenic stress impacts toward survivability and vulnerability surrounding C. rotundicauda eggs. Thus, warmer temperature is the recent climatic factor that adversely threaten coastal life especially those with long embryogenesis periods.

Hazardous chemical elements in aquatic ecosystems pose a major threat to habitats and the environment. This study is based on two parallel analyses at different scales and innovates methodologically within this approach, with continental-scale analysis using satellite imagery. At the macroscale, it aims to spectrally detect chlorophyll-a (CHL), water turbidity (TSM), and potential for suspended pollution (ADG443), through 472 satellite sampling points distributed in the Solimões River, Amazon River, and the estuarine region, during the dry (February) and rainy (August) seasons between 2019 and 2024. At the microscale, it seeks to quantify the main chemical elements present in nanoparticles and ultrafine particles incorporated into sediments collected in the Amazon River. Sediment sampling was conducted at 18 sites, nine upstream and nine downstream of the city of Manaus, Brazil, during the dry season (February) and the wet season (August) of 2024. Sediment analyses were conducted using focused ion beam scanning electron microscopy (FIB-SEM) and high-resolution transmission electron microscopy (HR-TEM), both of which were coupled with energy-dispersive X-ray spectroscopy (EDS). The results revealed the presence of toxic elements such as chromium (Cr) and vanadium (V) in nanoparticles smaller than 15 nm. The findings demonstrate that the convergence of high sediment contamination and increasing trophic instability pose a systemic risk to the world's largest freshwater system, necessitating urgent global environmental monitoring and the implementation of advanced conservation frameworks to safeguard both biodiversity and local riverside population.