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Marine heatwaves (MHWs) and total heat exposures (THEs), extreme warming events occurring across the global oceans, seriously threaten marine ecosystems and coastal communities as the climate warms. However, future changes in MHWs and THEs in the Arctic Ocean, where unique marine ecosystems are present, are still unclear. Here, based on the latest CMIP6 climate simulations, we find that both MHWs and THEs in the Arctic Ocean are anticipated to intensify in a warming climate, mainly due to Arctic sea ice decline and long-term warming trend, respectively. Particularly striking is the projected rise in MHW mean intensity during the 21 st century in the Arctic Ocean, surpassing the global average by more than sevenfold under the CMIP6 SSP585 scenario. This phenomenon, coined the 'Arctic MHW Amplification', underscores an impending and disproportionately elevated threat to the Arctic marine life, necessitating targeted conservation and adaptive strategies., (© 2024. The Author(s).)

It is important to determine the relationship between the concentration of chlorophyll a (Chla) and the inherent optical properties (IOPs) of ocean water to develop optical models and algorithms that characterize the biogeochemical properties and estimate biological pumping and carbon flux in this environment. However, previous studies reported relatively large variations in the particulate backscattering coefficient (b bp (λ)) and Chla from more eutrophic high-latitude waters to clear oligotrophic waters, especially in oligotrophic oceanic areas where these two variables have little covariation. In this study, we examined the variability of b bp (λ) and Chla in the euphotic layer in oligotrophic areas of the tropical Western Pacific Ocean and determined the sources of these variations by reassessment of in-situ measurements and the biogeochemical-argo (BGC-Argo) database. Our findings identified covariation of b bp (λ) and Chla in the water column below the deep Chla maximum (DCM) layer, and indicated that there was no significant correlation relationship between b bp (λ) and Chla in the upper layer of the DCM. Particles smaller than 3.2 µm that were in the water column above the DCM layer had a large effect on the b bp (λ) in the vertical profile, but particles larger than 3.2 µm and smaller than 10 µm had the largest effect on the b bp (λ) in the water column below the DCM layer. The contribution of non-algal particles (NAPs) to backscattering is up to 50%, which occurs in the water depth of 50 m and not consistent with the distribution of Chla. Phytoplankton and NAPs were modeled as coated spheres and homogeneous spherical particles to simulate the b bp (λ) of the vertical profile by Aden-Kerker method and Mie theory, and the results also indicated that the backscattering caused by particles less than 20 µm were closer to the measured data when they were below and above the DCM layer, respectively. This relationship also reflects the b bp (λ) of particles in the upper water was significantly affected particle size, but b bp (λ) in the lower water was significantly affected by Chla concentration. This effect may have relationship with phytoplankton photoacclimation and the relationship of a phytoplankton biomass maximum with particle size distribution in the water column according to the previous relevant studies. These characteristics also had spatial and seasonal variations due to changes of Chla concentration at the surface and at different depths. There was mostly a linear relationship between Chla and b bp (700) during winter. During other seasons, the relationship between these two variables was better characterized by a power function (or a logarithmic function) in the lower layer of the DCM. The spatial and vertical relationships between the b bp (λ) and Chla and the corresponding variations in the types of particles described in this study provide parameters that can be used for accurate estimation of regional geochemical processes.

The Arctic Ocean has experienced rapid warming and sea ice loss in recent decades, becoming the first open-ocean basin to experience widespread aragonite undersaturation [saturation state of aragonite (Ω arag ) < 1]. However, its trend toward long-term ocean acidification and the underlying mechanisms remain undocumented. Here, we report rapid acidification there, with rates three to four times higher than in other ocean basins, and attribute it to changing sea ice coverage on a decadal time scale. Sea ice melt exposes seawater to the atmosphere and promotes rapid uptake of atmospheric carbon dioxide, lowering its alkalinity and buffer capacity and thus leading to sharp declines in pH and Ω arag . We predict a further decrease in pH, particularly at higher latitudes where sea ice retreat is active, whereas Arctic warming may counteract decreases in Ω arag in the future.

Islands are one of the most sensitive interfaces between global changes and land and sea dynamic effects, with high sensitivity and low stability. Therefore, under the dynamic coupling effect of human activities and frequent natural disasters, the vulnerability of the ecological environment of islands shows the characteristics of complexity and diversity. For the protection of island ecosystems, a system for the assessment of island ecosystems and studies on the mechanism of island ecological vulnerability are highly crucial. In this study, the North and South Changshan Islands of China were selected as the study area. Considering various impact factors of island ecological vulnerability, the geographical information systems (GIS) spatial analysis, field surveys, data sampling were used to evaluate island ecological vulnerability. The Bayesian network model was used to explore the impact mechanism of ecological vulnerability. The results showed that the ecological vulnerability of the North Changshan Island is higher than that of the South Changshan Island. Among all the indicators, the proportion of net primary productivity (NPP) and the steep slope has the strongest correlation with ecological vulnerability. This study can be used as references in the relevant departments to formulate management policies and promote the sustainable development of islands and their surrounding waters.

Many of the world's largest deltas are sinking due to multiple natural and anthropogenic causes. This is particularly evident for the modern Yellow River Delta (YRD) in China, which is one of the most dynamic coastal systems on Earth. The YRD has experienced complicated patterns of accretion and erosion as well as significant compaction settlements. However, spatiotemporal variability and the long-term settlement rates law in this complex delta system remain poorly understood. Evidently, the surface settlement is supposedly controlled by a long-term natural compaction process of sediments. We first combined the Small Baseline Subset (SBAS) Interferometric Synthetic Aperture Radar (InSAR) method with a geotechnical model and geological, geomorphological, hydrogeological, and geotechnical data to assess the delta-wide long-term spatiotemporal settlement triggered by the consolidation and compaction of river sediments. The combination of satellite and field observations allows us to gain insights into the primary processes controlling surface movement. A total of seventy-five SAR images acquired by ERS and Envisat from 1992 to 2010 are used to generate three independent interferometric subsets calibrated with leveling to unveil spatiotemporal settlement variability. The densely distributed spatiotemporal measurements enable us to acquire the characteristics of the spatiotemporal variations of land movements. Moreover, the annual average settlement rates are observed within a range of 0 to >30 mm. Results suggest that the relative inland stability of the delta contrasts with the decreasing coastal margin trend at an average annual rate of 15 mm. Moreover, the variability is significantly correlated with the delta evolution and variations in subsoil architecture. A comparative analysis has also been conducted between time series InSAR measurements and the theoretical estimates of settlement derived from the geotechnical model. The strong agreement between the InSAR measurements and the geotechnical modeled results indicates that long-term settlement (in a decade-to-century scale) is primarily driven by the compaction of river sediments. The more the delta sub-lobe was newly formed, the more significant the settlement. Decreasing trends in annual settlement rates from approximately 70 mm to 0 mm in the long-term deposit compaction process are also identified. These findings are useful to understand the YRD morphological evolution and may provide insights into the changes in other deltas worldwide., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Aqueous energy-storage systems have attracted wide attention due to their advantages such as high security, low cost, and environmental friendliness. However, the specific chemical properties of water induce the problems of narrow electrochemical stability window, low stability of water-electrode interface reactions, and dissolution of electrode materials and intermediate products. Therefore, new low-cost aqueous electrolytes with different water chemistry are required. The nature of water depends largely on its hydroxyl-based hydrogen bonding structure. Therefore, the super-concentrated hydroxyl-rich sugar solutions are designed to change the original hydrogen bonding structure of water. The super-concentrated sugars can reduce the free water molecules and destroy the tetrahedral structure, thus lowering the binding degree of water molecules by breaking the hydrogen bonds. The ionic electrolytes based on super-concentrated sugars have the expanded electrochemical stability window (up to 2.812 V), wide temperature adaptability (-50 to 80 °C), and fair ionic conductivity (8.536 mS cm -1 ). Aqueous lithium-, sodium-, potassium-ion batteries and supercapacitors using super-concentrated sugar-based electrolytes demonstrate an excellent electrochemical performance. The advantages of ultralow cost and high universality enable a great practical application potential of the super-concentrated sugar-based aqueous electrolytes, which can also provide great experimental and theoretical assistance for further research in water chemistry., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)