The unprecedented COVID-19 outbreak impacted the world in many aspects. Air pollutants were largely reduced in cities worldwide in 2020. Using samples from two snow pits dug separately in 2019 and 2020 in Urumqi Glacier No. 1 (UG1) in the Xinjiang Uygur Autonomous Region (Xinjiang), China, we measured water-stable isotopes, soluble ions, and black and organic carbon (BC and OC). Both carbon types show no significant variations in the snow-pit profiles dated from 2018 through 2020. The deposition of anthropogenically induced soluble ions (K+, Cl-, SO42-, and NO3-) in the snow decreased to 20-40% of their respective concentrations between 2019 and 2020; however, they increased 2- to fourfold from 2018 to 2019. We studied the daily concentrations of SO2 (2019-2020), NO2 (2015-2020), CO (2019-2020), and PM2.5 (2019-2020) measured in the sixteen major cities and towns across Xinjiang. The variabilities in these air pollutants were supposed to illustrate the air quality in the urban area and represent the change in the source area. The NO2 decreased in response to mobility restrictions imposed by local governments, while SO2, CO, and PM2.5 did not consistently correspond. This difference indicates that the restriction measures primarily affected traffic. The increases in chemical species in the snow from 2018 to 2019 and the subsequent decreases from 2019 to 2020 were consistent with the variations in SO2 and NO2 measured in urban air and estimated by MERRA-2 model. Therefore, the pandemic could possibly have an impact on snow chemistry of the Tien-Shan glaciers via reduced traffic and industrial intensity; more evidence would be obtained from ice cores, tree rings, and other archives in the future.

Tibetan glaciers are natural documents of the specific biomass burning biomarker levoglucosan from regions around. However, knowledge about the characteristics of levoglucosan distributions on Tibetan glaciers under the different climate systems is poorly understood. In this study, we detected levoglucosan in snow samples from the Zuoqiupu (ZQP) Glacier affected by the Indian summer monsoon and the Muji (MJ) Glacier dominated by the westerlies. Results found that the ZQP Glacier was more heavily affected by fire emissions than the MJ Glacier, caused by stronger emission sources on the windward direction and shorter transport distances. Elevations for the appearance of levoglucosan maxima on glacier surfaces are roughly around the equilibrium line altitudes. However, levoglucosan displays a wider distribution range on the MJ glacier than on the ZQP glacier due to weaker summer melt. Injection height of fire smokes and glacial melt can affect the altitudinal distribution of levoglucosan. Black carbon and levoglucosan show different temporal variations in snow-pit samples on those two glaciers. The post depositional effects, e.g. the melting and refreezing processes, can modulate the vertical distribution of levoglucosan in snow/ice layers. Our results are helpful for understanding the geochemical behaviors of levoglucosan happened on Tibetan glacier surfaces. (C) 2016 Elsevier Ltd. All rights reserved.

Spectral albedos of open water, nilas, nilas with frost flowers, slush, and first-year ice with both thin and thick snow cover were measured in the East Antarctic sea-ice zone during the Sea Ice Physics and Ecosystems experiment II (SIPEX II) from September to November 2012, near 65 degrees S, 120 degrees E. Albedo was measured across the ultraviolet (UV), visible and near-infrared (nIR) wavelengths, augmenting a dataset from prior Antarctic expeditions with spectral coverage extended to longer wavelengths, and with measurement of slush and frost flowers, which had not been encountered on the prior expeditions. At visible and UV wavelengths, the albedo depends on the thickness of snow or ice; in the nIR the albedo is determined by the specific surface area. The growth of frost flowers causes the nilas albedo to increase by 0.2-0.3 in the UV and visible wavelengths. The spectral albedos are integrated over wavelength to obtain broadband albedos for wavelength bands commonly used in climate models. The albedo spectrum for deep snow on first-year sea ice shows no evidence of light-absorbing particulate impurities (LAI), such as black carbon (BC) or organics, which is consistent with the extremely small quantities of LAI found by filtering snow meltwater. Estimated BC mixing ratios were in the range 0.1-0.5 ng of carbon per gram of snow.

We present concentrations of environmentally available (unfiltered acidified 2% v/v HNO3) As, Cu, Cd, Pb, V, Sr, and major ions including Ca2+, Cl-, and SO42- in a July 2005 and a March 2006 shallow snow profile from the lower Eliot Glacier, Mount Hood, Oregon, and its proglacial stream, Eliot Creek. Low enrichment factors (EF) with respect to crustal averages suggests that in fresh March 2006 snow environmentally available elements are derived primarily from lithogenic Sources. Soluble salts Occurred in lower and less variable concentrations in July 2005 snow than March 2006. Conversely, environmentally available trace elements Occurred in greater and more variable concentrations in July 2005 than March 2006 snow. Unlike major Solutes, particulate-associated trace elements are not readily eluted during the melt season. Additionally, elevated surface concentrations suggest that they are likely added throughout the year via dry deposition. In a 1-h stream sampling, ratios of dissolved (<0.45 mu m) V : Cl-, Sr : Cl-, and Cu : Cl- are enriched in the Eliot Stream with respect to their environmentally available trace element to Cl- ratios in Eliot Glacier snow, suggesting chemical weathering additions in the stream waters. Dissolved Ph : Cl- is depleted in the Eliot Stream with respect to the ratio of environmentally available Pb to Cl- in snow, corresponding to greater adsorption onto particles at greater pH values. Copyright (C) 2009 John Wiley & Sons, Ltd.

Quantifying combustion aerosols transported to Summit, Greenland has typically involved the measurement of water-soluble inorganic and organic ions in air, snow, and ice. However, the ubiquitous nature of atmospheric soluble ions makes it difficult to separate the combustion component from the natural component. More specific combustion indicators are therefore needed to accurately quantify inputs from biomass and fossil-fuel burning. This work reports on radiocarbon (C-14) analysis of elemental carbon (EC) and quantification of polycyclic aromatic hydrocarbons (PAHs) of water-insoluble particles from a snowpit excavated at Summit, Greenland in 1996. The C-14 measurements allowed us to quantify the relative contribution of EC from biomass burning and fossil-fuel combustion transported to and deposited at Summit during periods of 1994 and 1995. Specific PAHs associated with conifer combustion helped to identify snowpit layers impacted by forest fires. Our results show that fossil EC was the major component during spring and fall 1994, while biomass EC and fossil EC were present in roughly equal amounts during summer 1994. PAH ratios in spring layers of the snowpit indicate substantial inputs from anthropogenic sources and the SigmaPAH depth profile displays springtime maxima that coincided with non-sea-salt sulfate ion maximum concentrations. In other layers, ammonium ion concentrations were independent of the isotopic and molecular carbon measurements. This work demonstrates the utility of radiocarbon techniques to quantify the two different sources of combustion-generated particles at Summit; however, portions of the 14 C results were indeterminate due to large uncertainties that were the result of chemical impurities introduced in the EC isolation technique. Additionally, PAH measurements were successfully performed on as little as 100 ml of snowmelt water, demonstrating the potential for future finer sample resolution. Published by Elsevier Science Ltd.