The ocean plays a major role in regulating the global climate by sequestering carbon, and dissolved organic carbon (DOC) represents one of the largest marine carbon reservoirs. Mesoscale eddies can enhance DOC export to the mesopelagic zone through eddy-wind interactions and eddy-induced strain, with this export often increasing during winter convective mixing. This study investigated how these processes affect DOC distribution and vertical fluxes within the anticyclonic Loop Current Eddy Yazoo in the oligotrophic Gulf of Mexico during the onset of Nortes winds in November 2022. Using high-spatial-resolution sampling along a transect, we mapped the spatial variability of DOC concentrations and hydrographic properties across LCE Yazoo and surrounding waters. We found pronounced horizontal and vertical variability in DOC concentrations and did not observe the hypothesized systematic enrichment within the eddy expected in a nutrient depleted environment. Total dissolved carbohydrates, which are important components of labile and semi-labile DOC fractions, accounted for 7.4% of total DOC in the epipelagic zone, decreasing to ~4% in the mesopelagic zone. Significant correlations were observed between DOC and Prochlorococcus, Synechococcus, picoeukaryotes, and heterotrophic bacterial biomass, indicating close spatial coupling between DOC and microbial community structure. Meanwhile, the relationship between DOC and apparent oxygen utilization in the oxycline indicated a greater apparent contribution of DOC remineralization to oxygen consumption within LCE Yazoo (~40%) than in adjacent waters (~29%). Upward and downward fluxes driven by eddy-Ekman pumping redistributed semi-labile DOC within the euphotic zone but did not result in net export. In contrast, upward and downward fluxes forced by eddy-induced strain led to the net subduction of semi-labile DOC, with particularly strong fluxes near the eddy edges. Overall, the findings support the idea that anticyclonic eddies may be important hotspots for semi-labile DOC export, potentially facilitating the microbial carbon pump in oligotrophic oceans.
In the sand-rich intervals of the Xihu Depression, identifying potential sealing beds is important for evaluating reservoir–seal relationships, particularly where continuous mudstone barriers may be limited. Calcareous sandstone interbeds may act as local barriers, but their distribution is difficult to trace because measured elemental calcium is sparse along the wells. This study combines well-log-based calcium-content prediction with lithology classification to identify calcareous sandstone and compare its distribution between wells. Calcium-content prediction from conventional logs achieved an R² of 0.89 and an RMSE of 0.52 percentage points. Predicted calcium was then combined with conventional logs and vertical features to identify six target lithologies. Among five classifiers compared on an internal test set of approximately 2, 000 records, AdaBoost achieved an accuracy of 0.88, balanced accuracy of 0.81, and macro-averaged F1 of 0.81. After model selection, the classifier was evaluated on 1, 900 labeled records from independent Well W4, achieving an accuracy of 0.82 and macro-averaged F1 of 0.76. The results support the identification of calcareous sandstone and interwell comparison of calcareous intervals. Some calcareous sandstone interbeds and mudstone overlie gas-bearing intervals, suggesting a potential reservoir–seal association; confirming effective sealing requires further petrophysical evidence.
The governance of marine plastic pollution has long been hindered by two significant challenges: the fragmentation of international norms and the disconnect between domestic legislation. The first challenge arises from the lack of alignment among international agreements—such as the United Nations Convention on the Law of the Sea, the London Convention, and the Basel Convention—regarding their scope and regulatory subjects. The second challenge is reflected in the dispersed nature of relevant regulations across various statutes and the inadequacy of the land-sea separation approach, which fails to effectively address the predominantly land-based origins of plastic pollution. The enactment of the 2026 Ecological and Environmental Code presents a new normative foundation aimed at alleviating these contradictions. This paper focuses on the Ecological and Environmental Code and employs three methodological approaches—normative analysis, comparative law, and legal hermeneutics—to explore its institutional framework. The analysis centers on two fundamental principles: integrated land-sea management and whole-life-cycle governance. It examines the Code’s provisions across three critical stages: source reduction, process control, and end-of-pipe disposal. The paper compares this Code with relevant extraterritorial legislative examples from the European Union, Japan, and South Korea. The study reveals that the Code effectively connects its General Provisions, the Pollution Prevention and Control Chapter, the Green and Low-Carbon Development Chapter, and the Legal Liability Chapter through internal coordination. This integrated land-sea management approach spans the regulatory chain from production to ocean discharge. The Code’s “multi-chapter synergy” structure offers distinct systemic advantages for comprehensive governance of marine plastic pollution across its life cycle, partially overcoming limitations in existing environmental law, which often neglects whole-life-cycle governance. Nonetheless, in comparison to standalone extraterritorial legislation, the Code shows institutional gaps in areas such as source-based total quantity control, specific operational rules for the Extended Producer Responsibility (EPR) regime, dynamic management of new pollutant lists, and alignment with international conventions. This paper suggests recommendations for improvement in three key areas: governance philosophy, institutional specifics, and performance mechanisms. These recommendations aim to serve as a theoretical reference for future revisions of the Code and for negotiations related to the Global Plastics Treaty, while also facilitating the effective alignment of domestic regulations with upcoming international frameworks.
Coastal-enclosure assessments commonly emphasize external organic loading, sediment processes, and hydrological exchange but rarely account for living benthic biomass that may become a transient internal organic load after habitat conversion. Omitting this pool may leave early post-closure oxygen budgets incomplete, particularly where water exchange and oxygen renewal are restricted. We evaluated this biological legacy in Saemangeum, Korea, using a three-step analysis: (1) estimating the pre-closure benthic carbon inventory and its complete-decomposition oxygen-demand upper bound; (2) using reanalyzed laboratory data to assess the temporal plausibility of rapid biomass loss and field-observed intertidal macrofaunal deficits to constrain potential demand; and (3) comparing the field-constrained estimates with standing dissolved-oxygen inventories across three effective receiving-water volumes. The compiled inventory contained 9,384 t C and yielded an all-component upper bound of 25,023 t O2; excluding the transferred bacterial estimate reduced this value to 14,461 t O2. At 120 days after closure, the net biomass-deficit and taxon-resolved minimum-loss estimators yielded potential demands of 3,547 and 4,663 t O2, respectively, equivalent to 54.0% and 70.9% of the intertidal macrofaunal upper bound. The corresponding point-estimate demand-to-inventory ratios exceeded one at an effective water volume of 0.35 km3 but remained below one at 0.83 and 1.27 km3. Among the tested assumptions, the inventory upper bound was most sensitive to the transferred bacterial stock, whereas the demand-to-inventory comparison was strongly influenced by receiving-water conditions. The tested alternative allocation and conversion-factor perturbations had smaller effects on the 120-day estimates. Conditional bootstrap intervals quantified sampling uncertainty in station-level means, while separate sensitivity analyses examined selected structural assumptions. These comparisons represent potential demand rather than realized oxygen consumption or predictions of hypoxia. The proposed tiered framework can identify coastal-enclosure projects requiring targeted monitoring and process-based oxygen-budget assessment.
Ice shelf melt rates by a warm ocean have a critical impact on ice sheet mass balance in Antarctica and in turn on the rates of sea level rise. Validating and tuning modeled ice shelf melt rates is a challenge. Here we discuss the issues by presenting validation of melt rates calculated from the Southern Ocean high-resolution model (SOhi) over the year 2007. SOhi includes full physics, tides, and an updated bathymetric compilation. We compare the model results to two satellite-derived estimates. Overall, we find that the model overestimates ice shelf melt, which we attribute to the ocean model initial (warm) conditions in some areas, bathymetric uncertainties in others, simplified physics on some ice shelves, and also to the inherent limitations of the satellite-derived estimates. The SOhi model nevertheless provides a comprehensive, detailed mapping of ice shelf melt rates around Antarctica; it captures higher melt near grounding lines and ice fronts, areas of freezing versus areas of high melt water production. The identified discrepancies between model and satellite-estimates provide guidelines for model improvements, requirements for additional observations of ice shelf cavities, and assembling of calibration/validation datasets to constrain the models.
