Dome A, the summit of the East Antarctic Ice Sheet, is an area challenging to access and is one of the harshest environments on Earth. Up until recently, long-term automated observations from Dome A ...(DA) were only possible with very low power instruments such as a basic meteorological station. To evaluate the characteristics of near-surface O3, continuous observations were carried out in 2016. Together with observations at the Amundsen–Scott Station (South Pole – SP) and Zhongshan Station (ZS, on the southeast coast of Prydz Bay), the seasonal and diurnal O3 variabilities were investigated. The results showed different patterns between coastal and inland Antarctic areas that were characterized by high concentrations in cold seasons and at night. The annual mean values at the three stations (DA, SP and ZS) were 29.2±7.5, 29.9±5.0 and 24.1±5.8 ppb, respectively. We investigated the effect of specific atmospheric processes on near-surface summer O3 variability, when O3 enhancement events (OEEs) are systematically observed at DA (average monthly frequency peaking at up to 64.5 % in December). As deduced by a statistical selection methodology, these O3 enhancement events (OEEs) are affected by significant interannual variability, both in their average O3 values and in their frequency. To explain part of this variability, we analyzed the OEEs as a function of specific atmospheric processes: (i) the role of synoptic-scale air mass transport over the Antarctic Plateau was explored using the Lagrangian back-trajectory analysis Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) method, and (ii) the occurrence of “deep” stratospheric intrusion events was investigated using the Lagrangian tool STEFLUX. The specific atmospheric processes, including synoptic-scale air mass transport, were analyzed by the HYSPLIT back-trajectory analysis and the potential source contribution function (PSCF) model. Short-range transport accounted for the O3 enhancement events (OEEs) during summer at DA, rather than efficient local production, which is consistent with previous studies of inland Antarctica. Moreover, the identification of recent (i.e., 4 d old) stratospheric-intrusion events by STEFLUX suggested that deep events only had a minor influence (up to 1.1 % of the period, in August) on deep events during the variability in near-surface summer O3 at DA. The deep events during the polar night were significantly higher than those during the polar day. This work provides unique data on ozone variation at DA and expands our knowledge of such events in Antarctica. Data are available at10.5281/zenodo.3923517 (Ding and Tian, 2020).
Abstract Language Nutrition, a term created to describe language exposure that is rich in quality and quantity and delivered in the context of social interactions, is crucial for a child's ...development and is strongly associated with his/her future literacy, academic achievement, and health. However, significant differences in children's early language environments contribute to disparities in their educational and health trajectories. Interventions, including book distribution programs, coaching parents to enrich their child's language environment, and public awareness campaigns, have all been shown to positively influence a child's access to language-rich interactions. Incorporating Language Nutrition coaching and literacy promotion into pediatrics is a promising platform for building the capacity of parents to provide language exposure to their children. By teaching parents both how and why to treat their child as a conversational partner and by modeling such interactions, pediatric health care providers can help parents set their children on a pathway toward literacy, educational success, and health.
Suspension feeding bivalves have the potential to mitigate estuarine and coastal marine eutrophication by permanently removing nitrogen (N) from the system. We conducted an integrated field and ...laboratory examination of the effect of eastern oyster biodeposition on sediment denitrification (DNF) and anammox (AMX) rates to quantify the N removal potential of oyster aquaculture using 2 commercial-scale sites in Chesapeake Bay, USA. Sediment N₂ production rates were measured using 2 techniques, 15N isotope tracer (n = 51) and N₂:Ar (n = 30). Oyster biodeposit N-load rates explained 21% of variation in sediment N₂ production (DNF and AMX). Oyster sediment N₂ production rates ranged from 0.00 to 1.56 mmol N m–2 d–1 and were almost always lower than reference sediments. From laboratory-based biodeposit addition and field-based forced biodeposit accumulation experiments, we found ~2.50 mmol N m–2 d–1 to be the maximum sediment N₂ production capacity of these sediments, regardless of increasing organic N or labile organic carbon delivery rates. We found no evidence to support the contention that biodeposition associated with oyster aquaculture significantly impacts annual N removal via sediment N₂ production, i.e. stimulation or inhibition, above reference rates, but there was evidence that sediment NH₄⁺ efflux rates were increased. We estimate the N removal rate via sediment N₂ production at similar oyster cultivation sites (1750 m²) with 5 × 10⁵ oysters ranges from 0.49 to 12.60 kg N yr–1, compared to 2.27 to 16.72 kg N yr–1 at reference sites. Thus, aquacultured oyster biodeposition did not have a ubiquitously enhancing effect on N removal rates via N₂ production and is therefore unlikely to be effective as a policy initiative for eutrophication mitigation.
The summit of the Antarctic plateau, Dome A, is proving to be an excellent site for optical, near-infrared, and terahertz astronomical observations. Gattini is a wide-field camera installed on the ...PLATO instrument module as part of the Chinese-led traverse to Dome A in 2009 January. We present here the measurements of sky brightness with the Gattini ultra-large field of view ( ) in the photometric B-, V-, and R-bands; cloud cover statistics measured during the 2009 winter season; and an estimate of the sky transparency. A cumulative probability distribution indicates that the darkest 10% of the nights at Dome A have sky brightness of SB = 22.98, SV = 21.86, and SR = 21.68 mag arcsec−2. These values were obtained during the year 2009 with minimum aurora, and they are comparable to the faintest sky brightness at Maunakea and the best sites of northern Chile. Since every filter includes strong auroral lines that effectively contaminate the sky brightness measurements, for instruments working around the auroral lines, either with custom filters or with high spectral resolution instruments, these values could be easily obtained on a more routine basis. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based site. These light curves will be published in a future paper.
A brief review is given of the major results from the last twenty years of astronomical site-testing in Antarctica. Suggestions are made for how to resolve some outstanding questions, such as the ...infrared sky background at Antarctic sites other than South Pole station.
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