Spatial Distributions of Picoplankton and Viruses in the Changjiang Estuary and Its Adjacent Sea Area during Summer

Simultaneous determination of picoplankton (i.e., Synechococcus spp., Prochlorococcus spp., picoeukaryotes, and heterotrophic bacteria) and viruses in the Changjiang (Yangtze) River estuary and its adjacent sea area was made using flow cytometry during a cruise in June 2006. The results show that Prochlorococcus in all samples was below detectable level. The abundances of Synechococcus, picoeukaryotes, heterotrophic bacteria, and viruses ranged from 0.00 to 1.22×108 cell L−1, 0.01×106 to 1.42×107 cells L−1, 8.40×107 to 4.29×109 cells L−1, and 1.20×107 to 1.06×1010 particles L−1, respectively. The determined picoplankton groups and viruses distinctly increased with the distance off the estuary and where the maximum abundance that occurred in these groups was different somewhat due to the individual sensitivity to environmental changes. Viral abundance showed a positive correlation with salinity and negative correlations with turbidity and inorganic nutrient concentrations. Positive linear relations were found between Synechococcus, heterotrophic bacteria, and viruses

Interaction pursuit in high-dimensional multi-response regression via distance correlation

Feature interactions can contribute to a large proportion of variation in many prediction models. In the era of big data, the coexistence of high dimensionality in both responses and covariates poses unprecedented challenges in identifying important interactions. In this paper, we suggest a two-stage interaction identification method, called the interaction pursuit via distance correlation (IPDC), in the setting of high-dimensional multi-response interaction models that exploits feature screening applied to transformed variables with distance correlation followed by feature selection. Such a procedure is computationally efficient, generally applicable beyond the heredity assumption, and effective even when the number of responses diverges with the sample size. Under mild regularity conditions, we show that this method enjoys nice theoretical properties including the sure screening property, support union recovery, and oracle inequalities in prediction and estimation for both interactions and main effects. The advantages of our method are supported by several simulation studies and real data analysis.Comment: to appear in The Annals of Statistics (2016

Permutohedral complexes and rational curves with cyclic action

We define a moduli space of rational curves with finite-order automorphism and weighted orbits, and we prove that the combinatorics of its boundary strata are encoded by a particular polytopal complex that also captures the algebraic structure of a complex reflection group acting on the moduli space. This generalizes the situation for Losev-Manin's moduli space of curves (whose boundary strata are encoded by the permutohedron and related to the symmetric group) as well as the situation for Batyrev-Blume's moduli space of curves with involution, and it extends that work beyond the toric context.Comment: 47 pages, 12 figure

Controlling Factors of Microplastic Riverine Flux and Implications for Reliable Monitoring Strategy

Embargo until December 12, 2022A significant proportion of marine plastic debris and microplastics is assumed to be derived from river systems. In order to effectively manage plastic contamination of the marine environment, an accurate quantification of riverine flux of land-based plastics and microplastics is imperative. Rivers not only represent pathways to the ocean, but are also complex ecosystems that support many life processes and ecosystem services. Yet riverine microplastics research is still in its infancy, and many uncertainties still remain. Major barriers exist in two aspects. First, nonharmonized sampling methodologies make it problematic for compiling data across studies to better estimate riverine fluxes of microplastics globally; Second, the significant spatiotemporal variation of microplastics in rivers which was affected by the river characteristics, MPs properties, etc. also have important influence on the estimation of riverine MPs fluxes. In this study, we made a comprehensive review from the above two aspects based on published peer-reviewed studies and provide recommendations and suggestions for a reliable monitoring strategy of riverine MPs, which is beneficial to the further establish sampling methods for rivers in different geographical locations. Besides, methods for achieving a high level of comparability across studies in different geographical contexts are highlighted. Riverine microplastic flux monitoring is another important part of this manuscript. The influential factors and calculation methods of microplastic flux in rivers are also discussed in this paper.acceptedVersio

Microfiber Hotspots’ Association with Ships in a Remote Port before and during Covid-19

Embargoed until 3. May 2024.During monthly water quality monitoring of Norwegian coastal waters, the sea surface waters off Brønnøysund, a remote port in Norway, exhibited an unexpectedly high abundance of microfibers. We further conducted monitoring of microplastics and microfibers from the surface waters off the city before and during the Covid-19 pandemic. Analysis of the microfiber characteristics, which were primarily comprised of cellulosic and polyester fibers, revealed similarities with those found in the global ocean, but at concentrations that were 1–4 orders of magnitude higher, with the maximum concentration reaching 491 n/L (0.34 mg/L). Source apportionment of microfibers using multivariate analyses based on simultaneous water chemistry data showed positive correlations with ships. Contrary to previous assumptions that marine microfibers were derived from land-based sources, our findings revealed that gray water discharge from ships significantly contributed to microfibers in the oceans. The demonstrated causations using path modeling between microfibers, gray water, shipping, and noncargo shipping activities call for urgent research and regulatory actions toward addressing plastic pollution in the UN Decade of Ocean Science.acceptedVersio

From Pollution To Solution: a global assessment of marine litter and plastic pollution

Outcome from working on the United Nations Environment Programme Advisory Group with the aim to address the UN Environment Assembly’s adopted resolution (UN/EA.4/RES.6) on Marine Plastic Litter and Microplastics by recommending indicators to harmonise monitoring and assessment and informing on policies and action environmentally sound technology innovations

Microplastics and nanoplastics in the marine-atmosphere environment

The discovery of atmospheric micro(nano)plastic transport and ocean-atmosphere exchange points to a highly complex marine plastic cycle, with negative implications for human and ecosystem health. Yet, observations are currently limited. In this Perspective, we quantify the processes and fluxes of the marine-atmospheric micro(nano)plastic cycle, with the aim of highlighting the remaining unknowns in atmospheric micro(nano)plastic transport. Between 0.013 and 25 million metric tons per year of micro(nano)plastics are potentially being transported within the marine atmosphere and deposited in the oceans. However, the high uncertainty in these marine-atmospheric fluxes is related to data limitations and a lack of study intercomparability. To address the uncertainties and remaining knowledge gaps in the marine-atmospheric micro(nano)plastic cycle, we propose a future global marine-atmospheric micro(nano)plastic observation strategy, incorporating novel sampling methods and the creation of a comparable, harmonized and global data set. Together with long-term observations and intensive investigations, this strategy will help to define the trends in marine-atmospheric pollution and any responses to future policy and management actions. Atmospheric transport of microplastics could be a major source of plastic pollution to the ocean, yet observations currently remain limited. This Perspective quantifies the known budgets of the marine-atmospheric micro(nano)plastic cycle and proposes a future global observation strategy.Peer reviewe