Abstract We first described the 2019 novel coronavirus infection in 10 children occurring in areas other than Wuhan. The coronavirus diseases in children are usually mild and epidemiological exposure is a key clue to recognize pediatric case. Prolonged virus shedding is observed in respiratory tract and feces at the convalescent stage.

To understand the epidemiological and clinical features of the symptomatic and asymptomatic pediatric cases of COVID-19, we carried out a prospective study in Shanghai during the period of January 19 to April 30, 2020. A total of 49 children (mean age 11.5 ± 5.12 years) confirmed with SARS-CoV-2 infection were enrolled in the study, including 11 (22.4%) domestic cases and 38 (77.6%) imported cases. Nine (81.8%) local cases and 12 (31.6%) imported cases had a definitive epidemiological exposure. Twenty-eight (57.1%) were symptomatic and 21 (42.9%) were asymptomatic. Neither asymptomatic nor symptomatic cases progressed to severe diseases. The mean duration of viral shedding for SARS-CoV-2 in upper respiratory tract was 14.1 ± 6.4 days in asymptomatic cases and 14.8 ± 8.4 days in symptomatic cases ( P > 0.05). Forty-five (91.8%) cases had viral RNA detected in stool. The mean duration of viral shedding in stool was 28.1 ± 13.3 days in asymptomatic cases and 30.8 ± 18.6 days in symptomatic participants ( P > 0.05). Children < 7 years shed viral RNA in stool for a longer duration than school-aged children ( P < 0.05). Forty-three (87.8%) cases had seropositivity for antibodies against SARS-CoV-2 within 1–3 weeks after confirmation with infection. In conclusion, asymptomatic SARS-CoV-2 infection may be common in children in the community during the COVID-19 pandemic wave. Asymptomatic cases shed viral RNA in a similar pattern as symptomatic cases do. It is of particular concern that asymptomatic individuals are potentially seed transmission of SARS-CoV-2 and pose a challenge to disease control.

As mass loss from the Greenland Ice Sheet accelerates, this modeling study considers how meltwater inputs to the ocean can impact marine ecosystems using a simplified fjord scenario. At marine‐terminating glaciers in Greenland fjords, meltwater can be delivered far below the sea surface, both as subglacial runoff (from atmosphere‐driven surface melt) and as basal melt (from ocean heat). Such delivery can result in buoyancy‐driven upwelling and the upward entrainment of nutrient‐rich deep water, which can support phytoplankton growth in fjord surface waters. For this study, we use an idealized fjord‐scale model to investigate which properties of glaciers and fjords govern the transport of buoyantly upwelled nutrients from fjords. We model the influence of fjord geometry, hydrology, wind, tides, and phytoplankton growth within the fjord on meltwater‐driven nutrient export to the ocean. We use the Regional Ocean Modeling System (ROMS) coupled to a buoyant plume model and a biogeochemical model to simulate physical and biogeochemical processes within an idealized tidewater glacial fjord. Results show that meltwater‐driven nutrient export increases with larger subglacial discharge rates and deeper grounding lines, features that are both likely to change with continued ice sheet melting. Nutrient export decreases with longer residence times, allowing greater biological drawdown. While the absence of a coastal current in the model setup prevents the downstream advection of exported nutrients, results suggest that shelf‐forced flows could influence nutrient residence time within fjords. This simplified model highlights key uncertainties requiring further observation to understand ecological impacts of Greenland mass loss.

Dissolved oxygen (O2) concentrations in waters of the ocean surface mixed layer are generally close to thermodynamic equilibrium with atmospheric concentrations. However, near‐surface O2 levels are also affected by other processes, including primary productivity, and thus measurements of near‐surface O2 can in theory be used to estimate productivity. Here we discuss variations in near‐surface O2 concentrations in the Strait of Georgia by examining a variety of data sets, focusing primarily on ferry‐based measurements over a 3‐year period (2015–2017). Both diurnal, seasonal, and interannual variations are quantified, and various fluxes into and out of the surface waters are estimated so that the degree to the measured oxygen variations representing biological activity can be assessed. On average, advective and vertical transport makes only a small negative contribution, while other budget terms show a strong seasonal cycle, lowest in winter, peaking in spring and slowly dropping to winter level during summer and autumn. For most of the year, the air‐sea flux is the largest term, but the storage term is important during the spring blooms. Diurnal variations of 5–10% saturation in measured oxygen levels must therefore largely reflect diurnal cycles in productivity and respiration. We estimate respiration effects from the rate of decay of O2 at night, which yields an average respiration rate of 459 mmol·m−2·day−1. This value is almost an order of magnitude larger than the other budget terms we have discussed, suggesting that a future focus on diurnal variations might provide most insight into biological processes in the Strait.