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Marine plastic pollution poses a potential threat to the ecosystem, but the sources and their magnitudes remain largely unclear. Existing bottom-up emission inventories vary among studies for two to three orders of magnitudes (OMs). Here, we adopt a top-down approach that uses observed dataset of sea surface plastic concentrations and an ensemble of ocean transport models to reduce the uncertainty of global plastic discharge. The optimal estimation of plastic emissions in this study varies about 1.5 OMs: 0.70 (0.13-3.8 as a 95% confidence interval) million metric tons yr-1 at the present day. We find that the variability of surface plastic abundance caused by different emission inventories is higher than that caused by model parameters. We suggest that more accurate emission inventories, more data for the abundance in the seawater and other compartments, and more accurate model parameters are required to further reduce the uncertainty of our estimate.

Sea ice models are essential tools for simulating the thermodynamic and dynamic processes of the sea ice and the coupling with the polar atmosphere and ocean. Popular models such as the Community Ice CodE (CICE) are usually based on non-moving, locally orthogonal Eulerian grids. However, the various in-situ observations such as ice tethered buoys and drift stations, are subjected to sea ice drift and hence by nature Lagrangian. Furthermore, the statistical analysis of sea ice kinematics requires the Lagrangian perspective. As a result, the offline sea ice tracking with model output is usually carried out for many scientific and validational practices. Certain limitations exist, such as the need of high frequency model outputs, as well unaccountable tracking errors. In order to facilitate Lagrangian diagnostics in current sea ice models, we design and implement an online Lagrangian tracking module in CICE under the coupled model system of CESM (Community Earth System Model). In this work, we introduce its design and implementation in detail, as well as the numerical experiments for the validation and the analysis of sea ice deformations. In particular, the sea ice model is forced with historical atmospheric reanalysis data and the Lagrangian tracking results are compared with the observed buoys' tracks for the years from 1979 to 2001. Moreover, high-resolution simulations are carried out with the Lagrangian tracking to study the multi-scale sea ice deformations modeled by CICE. Through scaling analysis, we show that CICE simulates multi-fractal sea ice deformations in both the spatial and the temporal domain, as well as the spatial-temporal coupling characteristics. The analysis with model output on the Eulerian grid shows systematic difference with the Lagrangian tracking-based results, highlighting the importance of the Lagrangian perspective for scaling analysis. Related topics, including the subdaily sea ice kinematics and the potential application of the Lagrangian tracking module, are also discussed. [ABSTRACT FROM AUTHOR]

Purpose: Aberrant crypt foci (ACF) of the colon are possible precursors of adenoma and cancer. beta-catenin alterations are early events in human colorectal carcinogenesis. beta-catenin expression is altered in colorectal cancer, adenoma, and ACF with dysplasia. Here, we describe the expression of beta-catenin in ACF, especially nondysplastic ACF., Methods: Rectal chromoscopy with 4% indigo carmine was performed on 418 subjects and 146 biopsy specimens, including 10 dysplastic ACF, 106 nondysplastic ACF, and 30 normal colonic mucosal controls taken under endoscopy. The expression and subcellular distribution of beta-catenin were assessed by immunohistochemistry., Results: beta-catenin expression was altered in 1 of 30 (3.3%) normal mucosa, 30 of 106 (28.3%) nondysplastic ACF, and 10 of 10 (100%) dysplastic ACF (P<0.001). Notably, most cells with altered beta-catenin expression in nondysplastic ACF were limited to the bottom of the crypt, where stem cells are located., Conclusions: Both dysplastic and nondysplastic ACF have altered beta-catenin expression and play a role in colon tumorigenesis.