Distribution and Driving Mechanism of N2O in Sea Ice and Its Underlying Seawater during Arctic Melt Season

Nitrous oxide (N2O) is the third most important greenhouse gas in the atmosphere, and the ocean is an important source of N2O. As the Arctic Ocean is strongly affected by global warming, rapid ice melting can have a significant impact on the N2O pattern in the Arctic environment. To better understand this impact, N2O concentration in ice core and underlying seawater (USW) was measured during the seventh Chinese National Arctic Research Expedition (CHINARE2016). The results showed that the average N2O concentration in first-year ice (FYI) was 4.5 ± 1.0 nmol kg−1, and that in multi-year ice (MYI) was 4.8 ± 1.9 nmol kg−1. Under the influence of exchange among atmosphere-sea ice-seawater systems, brine dynamics and possible N2O generation processes at the bottom of sea ice, the FYI showed higher N2O concentrations at the bottom and surface, while lower N2O concentrations were seen inside sea ice. Due to the melting of sea ice and biogeochemical processes, USW presented as the sink of N2O, and the saturation varied from 47.2% to 102.2%. However, the observed N2O concentrations in USW were higher than that of T-N2OUSW due to the sea–air exchange, diffusion process, possible N2O generation mechanism, and the influence of precipitation, and a more detailed mechanism is needed to understand this process in the Arctic Ocean.

Dynamics of the Spatial Chlorophyll-A Distribution at the Polar Front in the Marginal Ice Zone of the Barents Sea during Spring

Effects of the sea-ice edge and the Polar Frontal Zone on the distribution of chlorophyll-a levels in the pelagic were investigated during multi-year observations in insufficiently studied and rarely navigable regions of the Barents Sea. Samples were collected at 52 sampling stations combined into 11 oceanographic transects over a Barents Sea water area north of the latitude 75° N during spring 2016, 2018, and 2019. The species composition, abundance and biomass of the phytoplankton community, chlorophyll-a concentrations, hydrological and hydrochemical parameters were analyzed. The annual phytoplankton evolution phase, defined as an early-spring one, was determined throughout the transects. The species composition of the phytoplankton community and low chlorophyll-a levels suggested no phytoplankton blooming in April 2016 and 2019. Not yet started sea-ice melting prevented sympagic (sea-ice-associated) algae from being released into the seawater. In May 2018, ice melting began in the eastern Barents Sea and elevated chlorophyll-a levels were recorded near the ice edge. Chlorophyll-a concentrations substantially differed in waters of different genesis, especially in areas influenced by the Polar Front. The Polar Front separated the more productive Arctic waters with a chlorophyll-a concentration of 1–5 mg/m3 on average from the Atlantic waters where the chlorophyll-a content was an order of magnitude lower.

Significant methane undersaturation during austral summer in the Ross Sea (Southern Ocean)

Dissolved methane (CH4) was measured at 9 stations along a transect at 75° S in the Ross Sea during austral summer in January 2020. CH4 undersaturation (mean: 82 ± 20 %) was found in the water column, with a mean air-sea CH4 flux density of −0.58 ± 0.48 μmol m−2 day−1, which suggests that the Ross Sea was a net sink for atmospheric CH4 during the austral summer. Simple box-model calculations revealed that the CH4 depletion should occur in the surface mixed layer because of CH4 oxidation and advection of CH4-poor waters. We propose that freshwater injection caused by sea-ice melting in summer dilutes CH4 concentrations within the surface layer and thus increases its potential for atmospheric CH4 uptake in the Ross Sea. Thus, we argue that both CH4 consumption and sea-ice melting are important drivers of CH4 undersaturation, which implies that the high-latitude area of the Southern Ocean is a sink for atmospheric CH4. We estimated that the Southern Ocean (> 65° S) takes up about 0.02 % of the global CH4 emissions and thus represents a minor sink for atmospheric CH4.

Investigation of perfluoroalkyl substances in proglacial rivers and permafrost seep in a high Arctic watershed

We measured perfluoroalkyl substances (PFAS) in proglacial rivers and along a non-glacial freshwater continuum to investigate the role of snow and ice melting in their transport and fate within the Lake Hazen watershed (82° N).

Impact of local atmospheric intraseasonal variability on mean sea ice state in the Arctic Ocean

The Arctic atmosphere shows significant variability on intraseasonal timescales of 10-90 days. The intraseasonal variability in the Arctic sea ice is clearly related to that in the Arctic atmosphere. It is well-known that the Arctic mean sea ice state is governed by the local mean atmospheric state. However, the response of the Arctic mean sea ice state to the local atmospheric intraseasonal variability is unclear. The Arctic atmospheric intraseasonal variability exists in both the thermodynamical and dynamical variables. Based on a sea ice-ocean coupled simulation with a quantitative sea ice budget analysis, this study finds that: 1) the intraseasonal atmospheric thermodynamical variability tends to reduce sea ice melting through changing the downward heat flux on the open water area in the marginal sea ice zone, and the intraseasonal atmospheric dynamical variability tends to increase sea ice melting by a combination of modified air-ocean, ice-ocean heat fluxes and sea ice deformation. 2) The intraseasonal atmospheric dynamical variability increases summertime sea ice concentration in the Beaufort Sea and the Greenland Sea but decreases summertime sea ice concentration along the Eurasian continent in the East Siberia-Laptev-Kara Seas, resulting from the joint effects of the modified air-ocean, ice-ocean heat fluxes, the sea ice deformation, as well as the mean sea ice advection due to the changes of sea ice drift. The large spread in sea ice in the CMIP models may be partly attributed to the different model performances in representing the observed atmospheric intraseasonal variability. Reliable modeling of atmospheric intraseasonal variability is an essential condition in correctly projecting future sea ice evolution.

Nonlinear fractional arctic systems

In this contribution, the nonlinear fractional arctic sea ice model is given, and the solution of the model was obtained using a new proposed modified Adomian decomposition method. The result is compared with the integer-order model, and we observed that a model with fractional order gives a better result. We also observed that the effect of climate change on arctic sea ice could lead to a large-scale sea ice melting with sea-level rise for several meters, which could pose a major threat to low-lying island nations and coastal areas.

Contribution of ground ice melting to the expansion of Serling Co lake on the Tibetan Plateau

Serling Co lake, surrounded by permafrost and glacier-occupied regions, has exhibited the greatest increase in water storage over the last 50 years among all the lakes on the Tibetan Plateau. However, increases in precipitation and glacial melting are not enough to explain the increased water volume of lake expansion. The magnitude of the contribution of thawing permafrost to this increase under climate warming remains unknown. This study made the first attempt to quantify the water contribution of ground ice melting to the expansion of Serling Co lake by evaluating the ground surface deformation. We monitored the spatial distribution of surface deformation in the Serling Co basin using the SBAS-InSAR technique and compared it with the findings of field surveys. Then, the ground ice meltwater volume in the watershed was calculated based on the long-term deformation rate. Finally, this volume was compared with the lake volume change during the same period, and the contribution ratio was derived. SBAS-InSAR monitoring during 2017–2020 illustrated widespread and large subsidence in the upstream section of the Zhajiazangbu subbasin, where widespread continuous permafrost is present. The terrain subsidence was normally between 5 and 20 mm/a, indicating rapid ground ice loss in the region. The ground ice meltwater reached 56.0 × 106 m3/a, and the rate of increase in lake water storage was 496.3 × 106 m3/a during the same period, with ground ice meltwater contributing 11.3 % of the lake volume increase. This study is especially helpful in explaining the rapid expansion of Serling Co lake and equilibrating the water balance at the watershed scale. More importantly, the proposed method can be easily extended to other watersheds underlain by permafrost and to help understand the hydrologic changes in these watersheds.

Ozone Ice as an Oxygen Release Reagent for Heap Leaching of Gold Ore

The issue of poor aeration efficiency and low oxygen transfer in the heap leaching of gold has gained considerable attention. In this study, ozone ice was studied as an oxygen release reagent in the cyanide heap leaching of gold at a low temperature of approximately 5 °C, owing to its effective oxidation and clean and green properties. Quartz Crystal Microbalance with Dissipation (QCM-D) was used to monitor the effect of different ratios of cyanide and oxygen concentrations on the gold leaching rate. The results showed that the leaching rate doubled when the dissolved oxygen (DO) was increased from 8.2 mg/L to 12 mg/L at a relatively high cyanide concentration of 60 mg/L. The release of oxygen during the process of ozone ice melting was analyzed by simulating the oxygen-deficient condition of the ore heap in column leaching. In the first stage of ice melting, the DO in the solution increased dramatically, and the rate of increase improved with increased initial ozone concentration in the ice. In the second stage of ice melting, the rate of increase in the DO of the solution was not significantly affected by the initial ozone concentration in the ice; this was consistent with the decomposition rate of ozone. The addition of ozone ice containing 300 mg/L ozone increased the gold extraction by 4.1% in the ore column leaching experiment, compared to a column with no ozone ice. However, continuously increasing the ozone concentration up to 600 mg/L had no further significant effect, because the dissolved oxygen in the leaching solution reached saturation. The results facilitate a better understanding of the decomposition law of ozone in the melting process of ozone ice and help to improve the oxygen deficit state in gold leaching heaps.

Dynamic Europa ocean shows transient Taylor columns and convection driven by ice melting and salinity

The deep (~100 km) ocean of Europa, Jupiter’s moon, covered by a thick icy shell, is one of the most probable places in the solar system to find extraterrestrial life. Yet, its ocean dynamics and its interaction with the ice cover have received little attention. Previous studies suggested that Europa’s ocean is turbulent using a global model and taking into account non-hydrostatic effects and the full Coriolis force. Here we add critical elements, including consistent top and bottom heating boundary conditions and the effects of icy shell melting and freezing on ocean salinity. We find weak stratification that is dominated by salinity variations. The ocean exhibits strong transient convection, eddies, and zonal jets. Transient motions organize in Taylor columns parallel to Europa’s axis of rotation, are static inside of the tangent cylinder and propagate equatorward outside the cylinder. The meridional oceanic heat transport is intense enough to result in a nearly uniform ice thickness, that is expected to be observable in future missions.

The Calculation Method of Ice Melting Schemes’ Relay Protection Settings and Clarification of the Ice Depositions Control Method on Steel Lightning Protection Wires

The method of current values calculation of overcurrent and undercurrent relay protections included in the complex of relay protection of ice melting schemes by alternating current on steel lightning protection wires of overhead transmission lines is analysed. A comparison with the generally accepted method, called the element-by-element method, is made. The element-by-element method is based on using the parameters of all the elements included in the ice melting scheme to calculate the maximum and minimum melting currents, from which the corresponding protections must be adjusted. These parameters have a significant variation, especially the active and internal reactive resistances of steel lightning protection wires at alternating current, what increases the calculation error. The proposed method, called the recalculation method, is based on the use of the trial melting mode parameters, carried out annually in the autumn season on lightning protection wires, with a duration up to 2 minutes. In difference to the usual practice, the trial melting has to be carried out 2 times with different currents. According to the parameters of the mode the settings of relay protection are recalculated using the given methods. The methodological and additional errors of the new method are estimated, that shows proposed method advantage. The parameters of the trial melting mode can be used to specify the methodology for remote control of ice formation (the length of the ice formation zone).