scholarly journals Salts and Their Distribution in the McMurdo Region, Antarctica

2021 ◽  
Author(s):  
◽  
John Ross Keys
Keyword(s):  
Chemical Weathering ◽  
Sea Water ◽  
Regional Scale ◽  
Regional Distribution ◽  
Chemical Properties ◽  
Liquid Films ◽  
Sodium Sulphate ◽  
Separation Processes ◽  
Salt Migration ◽  
Taylor Valley

<p>Salts are widespread in the cold, arid McMurdo region of Antarctica. They exist in a variety of deposit types from massive subglacial and sub-lake deposits containing up to 1010 kilograms of salt, down to traces in soil, snow and ice. However, deposits on rock and soil typically amount to a few grams of salt. At least 30 salt phases are known but only 10 of these are widespread. These 10 are thenardite, gypsum, halite, calcite, darapskite, soda nitre, mirabilite, bloedite, epsomite and hexahydrite. The distribution of salts has been examined on two scales, local and regional. The local scale extends from individual deposits to areas of a few square kilometres. The regional scale covers McMurdo oasis, McMurdo Sound and Ross Island, though areas in McMurdo oasis, and particularly Taylor Valley receive most attention. Local distribution is controlled by salt migration and separation. Migration is induced by water and wind, with soil brines moving as thin liquid films, by capillarity and under the influence of gravity. Deflation and asymmetric salt accumulation provide evidence that wind is important. Separation of phases is a consequence of different physico-chemical properties of salts, and environmental conditions, including site aspect, ambient temperature and humidity. Eutectic temperature is a fundamental salt property but solubility is also important. Several salt deposits containing separated (fractionated) phases have been found in the region. Separation is achieved mainly by fractional dissolution and crystallization and the most evolved product of the general separation sequence is calcium chloride. The separation processes, together with salt migration, obscure the sources of the salts. Regional distribution of salts has been characterized by determining the relative frequency at which specific phases are encountered at increasing distance from the coast and above sea level. Chloride and sodium phases decrease, whereas magnesium phases increase in frequency away from the coast. Sulphates-to-chloride and nitrates-to-chloride ratios increase with increasing distance. Calcium and carbonate show little change except in Taylor Valley where a marked decrease is apparent. This regional distribution is mainly dependent on the sources of the salts. The marine source is most important, contributing almost all of the chloride, sodium, sulphate and probably nitrate ions that are present. Chemical weathering is the predominant source of magnesium, calcium and carbonate ions probably via reactions of mafic, ferromagnesian minerals in local rocks and regolith. Biological and volcanic activity are locally significant at eastern Taylor Valley and in the summit area of Erebus Volcano, respectively. The salts have accumulated over the lifetime of the region, that is over less than the last 20-25 Ma or so. There is no evidence that they are relics from earlier, preglacial times, except for very minor amounts of gypsum and calcium carbonate. There has been a recent influx of sea water into Taylor Valley perhaps between 50,000 and 20,000 years ago, and evaporation of this water has preceded advance of Taylor Glacier over part of the resulting salt deposit. The continuing interaction between glacier and salt is causing basal ice to melt and producing aperiodic discharges of up to a few thousand cubic metres of salty water from the terminus of the glacier.</p>

scholarly journals Salts and Their Distribution in the McMurdo Region, Antarctica

2021 ◽  
Author(s):  
◽  
John Ross Keys
Keyword(s):  
Chemical Weathering ◽  
Sea Water ◽  
Regional Scale ◽  
Regional Distribution ◽  
Chemical Properties ◽  
Liquid Films ◽  
Sodium Sulphate ◽  
Separation Processes ◽  
Salt Migration ◽  
Taylor Valley

<p>Salts are widespread in the cold, arid McMurdo region of Antarctica. They exist in a variety of deposit types from massive subglacial and sub-lake deposits containing up to 1010 kilograms of salt, down to traces in soil, snow and ice. However, deposits on rock and soil typically amount to a few grams of salt. At least 30 salt phases are known but only 10 of these are widespread. These 10 are thenardite, gypsum, halite, calcite, darapskite, soda nitre, mirabilite, bloedite, epsomite and hexahydrite. The distribution of salts has been examined on two scales, local and regional. The local scale extends from individual deposits to areas of a few square kilometres. The regional scale covers McMurdo oasis, McMurdo Sound and Ross Island, though areas in McMurdo oasis, and particularly Taylor Valley receive most attention. Local distribution is controlled by salt migration and separation. Migration is induced by water and wind, with soil brines moving as thin liquid films, by capillarity and under the influence of gravity. Deflation and asymmetric salt accumulation provide evidence that wind is important. Separation of phases is a consequence of different physico-chemical properties of salts, and environmental conditions, including site aspect, ambient temperature and humidity. Eutectic temperature is a fundamental salt property but solubility is also important. Several salt deposits containing separated (fractionated) phases have been found in the region. Separation is achieved mainly by fractional dissolution and crystallization and the most evolved product of the general separation sequence is calcium chloride. The separation processes, together with salt migration, obscure the sources of the salts. Regional distribution of salts has been characterized by determining the relative frequency at which specific phases are encountered at increasing distance from the coast and above sea level. Chloride and sodium phases decrease, whereas magnesium phases increase in frequency away from the coast. Sulphates-to-chloride and nitrates-to-chloride ratios increase with increasing distance. Calcium and carbonate show little change except in Taylor Valley where a marked decrease is apparent. This regional distribution is mainly dependent on the sources of the salts. The marine source is most important, contributing almost all of the chloride, sodium, sulphate and probably nitrate ions that are present. Chemical weathering is the predominant source of magnesium, calcium and carbonate ions probably via reactions of mafic, ferromagnesian minerals in local rocks and regolith. Biological and volcanic activity are locally significant at eastern Taylor Valley and in the summit area of Erebus Volcano, respectively. The salts have accumulated over the lifetime of the region, that is over less than the last 20-25 Ma or so. There is no evidence that they are relics from earlier, preglacial times, except for very minor amounts of gypsum and calcium carbonate. There has been a recent influx of sea water into Taylor Valley perhaps between 50,000 and 20,000 years ago, and evaporation of this water has preceded advance of Taylor Glacier over part of the resulting salt deposit. The continuing interaction between glacier and salt is causing basal ice to melt and producing aperiodic discharges of up to a few thousand cubic metres of salty water from the terminus of the glacier.</p>

scholarly journals Sea Water Characterization at Ujung Kulon Coastal Depth as Raw Water Source for Desalination and Potential Energy

2018 ◽  
Vol 31 ◽  
pp. 02005 ◽  
Author(s):  
Dan Mugisidi ◽  
Okatrina Heriyani
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Chemical Properties ◽  
Water Source ◽  
Sodium Sulphate ◽  
Raw Water ◽  
Energy Potential ◽  
Allowable Level ◽  
Physical And Chemical ◽  
And Chemical Properties

Fresh water is basic need for life while the source is limited. Therefore, sea water is used as fresh water through desalination process. Sea water has different physical and chemical properties ranging from the surface to the seabed. The energy potential that can be obtained from the hydrostatic pressure also changes according to the depth. As part of the research of the utilization of sea water into fresh water, the aim of this study is to know the characteristics of sea water in the depth that can be utilized as source of fresh water. The sea water samples were taken at 11km from Ujung Kulon beach with depth of 0m, 20m, 40m, 60m, 80m, and 100m under the surface. The results showed that the physical properties at every depth were below the maximum allowable drinking water except for the amount of dissolved solids. Chemical characteristics at any depth above allowable level were fluoride, hardness (CaCo3), chloride, sodium, sulphate, and (KMnO4). In addition to the properties, pressure is one of the considerations in this study to determine the depth of sea water as sources for desalination. Pressure increased by 36.11% as the depth of the sea increased.

Regional coupling between chest wall and lung expansion during HFV: a positron imaging study

1993 ◽  
Vol 74 (5) ◽  
pp. 2242-2252 ◽  
Author(s):  
J. G. Venegas ◽  
K. Tsuzaki ◽  
B. J. Fox ◽  
B. A. Simon ◽  
C. A. Hales
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Gas Transport ◽  
Regional Scale ◽  
Regional Distribution ◽  
Imaging Study ◽  
High Frequency Ventilation ◽  
Rib Cage ◽  
Lung Expansion ◽  
Frequency Ventilation

Apparently conflicting differences between the regional chest wall motion and gas transport have been observed during high-frequency ventilation (HFV). To elucidate the mechanism responsible for such differences, a positron imaging technique capable of assessing dynamic chest wall volumetric expansion, regional lung volume, and regional gas transport was developed. Anesthetized supine dogs were studied at ventilatory frequencies (f) ranging from 1 to 15 Hz and eucapnic tidal volumes. The regional distribution of mean lung volume was found to be independent of f, but the apex-to-base ratio of regional chest wall expansion favored the lung bases at low f and became more homogeneous at higher f. Regional gas transport per unit of lung volume, assessed from washout maneuvers, was homogeneous at 1 Hz, favored the bases progressively as f increased to 9 Hz, and returned to homogeneity at 15 Hz. Interregional asynchrony (pendelluft) and right-to-left differences were small at this large regional scale. Analysis of the data at a higher spatial resolution showed that the motion of the diaphragm relative to the excursions of the rib cage decreased as f increased. These differences from apex to base in regional chest wall expansion and gas transport were consistent with a simple model including lung, rib cage, and diaphragm regional impedances and a viscous coupling between lungs and chest wall caused by the relative sliding between pleural surfaces. To further test this model, we studied five additional animals under open chest conditions. These studies resulted in a homogeneous and f-independent regional gas transport. We conclude that the apex-to-base distribution of gas transport observed during HFV is not caused by intrinsic lung heterogeneity but rather is a result of chest wall expansion dynamics and its coupling to the lung.

Starch in the Oceans

1968 ◽  
Vol 25 (6) ◽  
pp. 1269-1284 ◽  
Author(s):  
Adam S. Bursa
Keyword(s):  
North Atlantic ◽  
Sea Water ◽  
Chemical Properties ◽  
Benthic Algae ◽  
Virgin Islands ◽  
Starch Grains ◽  
The North ◽  
The Baltic ◽  
Mass Mortalities ◽  
And Chemical Properties

Starch observed in arctic waters of Canada, in the Baltic and Mediterranean seas, in the North Atlantic and Indian oceans, and in the waters about Bermuda, the Virgin Islands, and Jamaica is formed mostly in Gymnodinioideae, benthic algae, and higher aquatic plants and rarely in planktonic Chlorophyceae. In these phytoflagellates the fragile pellicle breaks when there are critical changes in salinity, temperature, or pressure and is subsequently decomposed by bacteria. The starch retains its shape after destruction of the protoplast, and accumulates in large quantities in aquatic habitats. Standing crops of free starch grains mark past blooms and mass mortalities of phytoplankton. The largest potato-like starch grains found in the oceans appear to be derived from the ocellar lenses of Warnoviaceae.Though Protozoa and various herbivores may ingest free planktonic starch, they were not observed to digest it. Large standing crops of starch and monosaccharides derived from amylolysis may affect nutrition in some animals, and influence the optical and chemical properties of sea water. Amylogenesis in some dinoflagellates starts from chondriosomes which are specialized in this process. In Prorocentrideae starch is formed within the ectoplasmic reticulum.

Establishing a systematic regional scale identification of artificial ground in Catalan territory from geological perspective

2021 ◽  
Author(s):  
Guillem Subiela ◽  
Jordi Peña ◽  
Fus Micheo ◽  
Miquel Vilà
Keyword(s):  
Regional Scale ◽  
Chemical Properties ◽  
Medium Term ◽  
Related Information ◽  
Reference Information ◽  
Geological Processes ◽  
Digital Elevation ◽  
Natural Terrain ◽  
Systematic Identification ◽  
Physical And Chemical

&lt;p&gt;Anthropization is the transformation that human actions exert on the environment. Artificial interventions modify the morphology of the ground and affect physical and chemical properties of natural terrain. Therefore, providing information on the distribution of artificial ground throughout the territory is necessary for land management, development and sustainability. Despite the effects of anthropization, from a geological approach, the systematic characterization of anthropic ground on a regional scale is scarcely developed in Catalonia.&lt;/p&gt;&lt;p&gt;In the last decade, one of the lines of work of Institut Cartogr&amp;#224;fic i Geol&amp;#242;gic de Catalunya (the Catalan geological survey organisation) has been the development of the project Geoanthropic map of Catalonia, which incorporate information of active geological processes and artificial ground. Up to now, the activity in this project has broadly consisted of publishing several map sheets of 1:25.000 scale from different areas of Catalonia (5.000 km&lt;sup&gt;2&lt;/sup&gt; from 32.108,2 km&lt;sup&gt;2&lt;/sup&gt;). Recently, in the framework of this project, it is proposed to refocus with the purpose of &amp;#8203;&amp;#8203;providing information on these two themes from all over the territory. In this process, in relation to artificial interventions, an analysis has been carried out to determine which anthropic terrains and related information can be obtained for its usefulness in a systematic way in the medium term.&lt;/p&gt;&lt;p&gt;In this analysis, firstly, the available reference information sources have been established from which information on anthropic lands in Catalonia can be extracted. Basically, these documents are topographic maps, geothematic maps, land use map, digital elevation models and other historical cartographic documents. Much of the existing information in these sources must be redirected to a more geological approach so that it can be used to address aspects related to geotechnics, natural hazards, soil pollution and other environmental concerns.&lt;/p&gt;&lt;p&gt;Secondly, based on data analysis, a series of certain anthropic lands have been evaluated which can be captured on a systematic identification at regional scale. Thereby, the following anthropogenic terrains have been established: built-up areas, agricultural areas, sealed ground, urban compacity, worked grounds (e.g., related to mineral excavations and transport infrastructures), engineered embankments, infilled excavations and other more singular anthropogenic deposits. Therefore, from a geological perspective, it will be feasible to identify and map these anthropic lands and provide this information throughout the Catalan territory in the medium term.&lt;/p&gt;&lt;p&gt;Bearing in mind all the above, the presentation will consist of this general analysis and the considerations that have been extracted regarding this. In addition, the preliminary results of the systematically characterized artificial ground will be shown.&lt;/p&gt;

scholarly journals Stochastic Analysis of Electron Transfer and Mass Transport in Confined Solid/Liquid Interfaces

Surfaces ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 392-407
Author(s):  
Marco Favaro
Keyword(s):  
Electron Transfer ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Chemical Properties ◽  
Liquid Films ◽  
Liquid Interfaces ◽  
Electrical Potentials ◽  
Voltammetric Behavior ◽  
Current Densities ◽  
Solid Liquid

Molecular-level understanding of electrified solid/liquid interfaces has recently been enabled thanks to the development of novel in situ/operando spectroscopic tools. Among those, ambient pressure photoelectron spectroscopy performed in the tender/hard X-ray region and coupled with the “dip and pull” method makes it possible to simultaneously interrogate the chemical composition of the interface and built-in electrical potentials. On the other hand, only thin liquid films (on the order of tens of nanometers at most) can be investigated, since the photo-emitted electrons must travel through the electrolyte layer to reach the photoelectron analyzer. Due to the challenging control and stability of nm-thick liquid films, a detailed experimental electrochemical investigation of such thin electrolyte layers is still lacking. This work therefore aims at characterizing the electrochemical behavior of solid/liquid interfaces when confined in nanometer-sized regions using a stochastic simulation approach. The investigation was performed by modeling (i) the electron transfer between a solid surface and a one-electron redox couple and (ii) its diffusion in solution. Our findings show that the well-known thin-layer voltammetry theory elaborated by Hubbard can be successfully applied to describe the voltammetric behavior of such nanometer-sized interfaces. We also provide an estimation of the current densities developed in these confined interfaces, resulting in values on the order of few hundreds of nA·cm−2. We believe that our results can contribute to the comprehension of the physical/chemical properties of nano-interfaces, thereby aiding to a better understanding of the capabilities and limitations of the “dip and pull” method.

Zinc concentrations in juvenile flatfish

1979 ◽  
Vol 59 (3) ◽  
pp. 761-775 ◽  
Author(s):  
N. J. Milner
Keyword(s):  
Sea Water ◽  
Chemical Properties ◽  
Estuarine Fish ◽  
Physico Chemical ◽  
Zinc Cadmium ◽  
Iron And Zinc ◽  
Lead Levels ◽  
Zinc Concentrations ◽  
High Concentrations ◽  
Cadmium And Lead

In most demersal and some pelagic marine fish O- and I-group stages are found on inshore nursery grounds which are often situated in coastal indentations and estuarieswhere flushing rates are low and the build up of persistent pollutants can be correspondingly high. Their movements are restricted, only leaving the nursery areas towards the end of their second year (Lockwood, 1974; Riley, 1973). This, coupled with the fact that juveniles may be more susceptible than adults to pollutants, makes them particularly vulnerable to the potential hazards of inshore pollution.The physico-chemical properties of most trace metals, however, generally preclude their occurrence at high concentrations in sea water itself. Instead, most of the metal is transferred to the particulate phase of the water mass and to sedimentary reservoirs (Renfro, 1973) so that concentrations of metals in sea water very rarely reach levels which are known to be acutely toxic to fish. The main risk from direct effects of metals lies in poisoning resulting from internal accumulation.Little information is available on metal concentrations occurring in young fish. Hardisty et al. (1974) and Hardisty, Kartar & Sainsbury (1974) have examined zinc, cadmium and lead levels in O-group and older flounders from the Bristol Channel. Andersen, Dommasnes & Hesthagen (1973) found high concentrations of zinc in O- and I-group herring and sprat from Oslo Fjord, Cross & Brooks (1973) reported on manganese, iron and zinc concentrations in juvenile estuarine fish. Pentreath (1973 b) has reported on zinc concentrations in the organs of I-group plaice.

39.—Progress towards a Chemical Model for Sea Water.

1972 ◽  
Vol 72 (1) ◽  
pp. 389-399 ◽  
Author(s):  
Michael Whitfield
Keyword(s):  
Sea Water ◽  
Chemical Properties ◽  
Chemical Model ◽  
Chemical Oceanography

Chemical oceanography is fundamentally concerned with the chemical properties of sea water. In order to study these properties, and the interactions of sea waterkwith other phases, we must first have some concept of what sea water.

scholarly journals Increased absorption by coarse aerosol particles over the Gangetic–Himalayan region

2014 ◽  
Vol 14 (3) ◽  
pp. 1159-1165 ◽  
Author(s):  
V. S. Manoharan ◽  
R. Kotamarthi ◽  
Y. Feng ◽  
M. P. Cadeddu
Keyword(s):  
Atmospheric Aerosols ◽  
Radiative Forcing ◽  
Climate Models ◽  
Monsoon Season ◽  
Regional Scale ◽  
Chemical Properties ◽  
Aerosol Forcing ◽  
Post Monsoon Season ◽  
Absorbing Aerosols ◽  
Coarse Aerosol

Abstract. Each atmospheric aerosol type has distinctive light-absorption characteristics related to its physical/chemical properties. Climate models treat black carbon as the main light-absorbing component of carbonaceous atmospheric aerosols, while absorption by some organic aerosols is also considered, particularly at ultraviolet wavelengths. Most absorbing aerosols are assumed to be < 1 μm in diameter (sub-micron). Here we present results from a recent field study in India, primarily during the post-monsoon season (October–November), suggesting the presence of absorbing aerosols sized 1–10 μm. Absorption due to super-micron-sized particles was nearly 30% greater than that due to smaller particles. Periods of increased absorption by larger particles ranged from a week to a month. Radiative forcing calculations under clear-sky conditions show that super-micron particles account for nearly 44% of the total aerosol forcing. The origin of the large aerosols is unknown, but meteorological conditions indicate that they are of local origin. Such economic and habitation conditions exist throughout much of the developing world. Hence, large absorbing particles could be an important component of the regional-scale atmospheric energy balance.

Sign in / Sign up

Export Citation Format

Share Document