Desalination of brackish and sea water

International Nuclear Information System (INIS)

Shukla, Dilip R.

2005-01-01

In Pali, Rajasthan, a population of 4 lacs gets about 6 million liters of water. Only 34 out of 116 municipalities in AP get regular water. Desalination found acceptance because of the decreasing water table leading to high salinity and making conventional treatment methods irrelevant. While choosing amongst the competitive desalination techniques that are available today for conversion of large quantities of saline water, Reverse Osmosis (RO) and distillation techniques stand out. RO rules the brackish water market where feed salinity is over 700 mg/L. Waste heat is nowadays a non-entity in power plants due to the developments of waste heat recovery systems in power plant technology. Most of the large plants tend to choose thermal desalination. Improved RO economics have in turn increased the attractiveness and use of seawater reverse osmosis (SWRO) technology for many large drinking water projects through out the world. Energy cost is the single largest factor in the cost of Sea Water System (usually 20 to 30% of total cost of water). Nuclear Power Corporation, Kudankulam proposed to build a SW desalination system based on RO technology to meet the water requirement of the Anu Vijay Nagar township and Nuclear Power Station. Energy recovery turbine helps reduce the overall system energy requirement. (author)

A comparative study of boron and arsenic (III) rejection from brackish water by reverse osmosis membranes

KAUST Repository

Teychene, Benoî t; Collet, Gaelle; Gallard, Hervé ; Croue, Jean Philippe

2013-01-01

This study aims to compare at lab-scale the rejection efficiency of several reverse osmosis membranes (RO) toward arsenic (III) and boron during the filtration of a synthetic brackish water. The effect of pH and operating conditions on the rejection of each RO membrane was studied. Two types of membrane were investigated: "brackish water" and "sea water" membranes. Our results showed that the metalloid rejection depends on the membrane type, pH and transmembrane pressure applied. Increasing pH above the dissociation constant (pKa) of each specie improves significantly the metalloid rejection by RO membranes, whatever the membrane type. Moreover, at identical operating conditions (pH, transmembrane pressure), results showed that the brackish water membranes have a higher water flux and exhibit lower metalloid rejection. The highest As(III) rejection value for the tested brackish water membranes was 99% obtained at pH = 9.6 and 40 bars, whereas it was found that the sea water RO membranes could highly reject As(III), more than 99%, even at low pH and low pressure (pH = 7.6 and 24 bars).Regarding Boron rejection, similar conclusions could be drawn. The sea water RO membranes exert higher removal, with a high rejection value above 96% over the tested conditions. More generally, this study showed that, whatever the operating conditions or the tested membranes, the boron and As(III) permeate concentrations are below the WHO guidelines. In addition, new data about the boron and arsenic permeability of each tested RO membrane was brought thanks to a theoretical calculation. © 2012 Elsevier B.V.

A comparative study of boron and arsenic (III) rejection from brackish water by reverse osmosis membranes

KAUST Repository

Teychene, Benoît

2013-02-01

This study aims to compare at lab-scale the rejection efficiency of several reverse osmosis membranes (RO) toward arsenic (III) and boron during the filtration of a synthetic brackish water. The effect of pH and operating conditions on the rejection of each RO membrane was studied. Two types of membrane were investigated: "brackish water" and "sea water" membranes. Our results showed that the metalloid rejection depends on the membrane type, pH and transmembrane pressure applied. Increasing pH above the dissociation constant (pKa) of each specie improves significantly the metalloid rejection by RO membranes, whatever the membrane type. Moreover, at identical operating conditions (pH, transmembrane pressure), results showed that the brackish water membranes have a higher water flux and exhibit lower metalloid rejection. The highest As(III) rejection value for the tested brackish water membranes was 99% obtained at pH = 9.6 and 40 bars, whereas it was found that the sea water RO membranes could highly reject As(III), more than 99%, even at low pH and low pressure (pH = 7.6 and 24 bars).Regarding Boron rejection, similar conclusions could be drawn. The sea water RO membranes exert higher removal, with a high rejection value above 96% over the tested conditions. More generally, this study showed that, whatever the operating conditions or the tested membranes, the boron and As(III) permeate concentrations are below the WHO guidelines. In addition, new data about the boron and arsenic permeability of each tested RO membrane was brought thanks to a theoretical calculation. © 2012 Elsevier B.V.

Efficient Desalination of Brackish Ground Water via a Novel Capacitive Deionization Cell Using Nanoporous Activated Carbon Cloth Electrodes

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K. Laxman

2015-12-01

Full Text Available Sea water intrusion in ground water sources has made brackish water desalination a necessity in Oman. The application of capacitive deionization (CDI for the deionization of ground water samples from wells in Al-Musanaah Wilayat is proposed and demonstrated. A CDI cell is fabricated using nanoporous activated carbon cloth (ACC as the electrodes and is shown to be power efficient for desalting ground water samples with total dissolved solids (TDS of up to 4,000 mg/l. The CDI cell was able to remove up to 73% of the ionic scaling and fouling contaminants from brackish water samples. The power consumption for deionization of brackish water was estimated to be 1 kWh/m3 of desalinated water, which is much lower than the power required to process water with equivalent TDS by the reverse osmosis processes. The CDI process is elaborated, and observations and analysis of the ion adsorption characteristics and electrical properties of the capacitive cell are elucidated.

Impact of increased fuel costs and inflation on the cost of desalting sea water and brackish waters

International Nuclear Information System (INIS)

Reed, S.A.

1976-01-01

The combined increases in the cost of fuel, equipment, and money during the past four years have had a marked impact on the cost of desalting saline waters. The current costs of desalting seawater by distillation and reverse osmosis and brackish waters by reverse osmosis and electrodialysis as a function of plant size and feedwater chemistry are estimated. Typically, distillation plant capital costs have increased from dollar 1 per daily gallon to dollar 3 per daily gallon for large plants (100 Mgd) and from approximately dollar 1.40 per daily gallon to approximately dollar 5 per daily gallon per plant sizes of 5 Mgd or less. Consequently, water costs are now ranging from dollar 3 to dollar 4 per 1000 gal when oil is used to generate steam. Similarly, the costs of desalting inland brackish waters using reverse osmosis or electrodialysis have increased significantly

Firewood crops in areas of brackish water

Energy Technology Data Exchange (ETDEWEB)

Chaturvedi, A.N.

1984-01-01

Parts of the Mathura, Agra, Etah and Aligarh districts of Uttar Pradesh have a special problem of brackish water which is the result of the complete destruction of natural vegetation during a period of several centuries. Twenty species of trees and shrubs (listed) were planted during 1981-1982 in plots of 30 x 30 m at a spacing of 1.5 x 1.5 m. A detailed analysis of water from the Forest Research Station, Mathura is presented; pH ranged from 7.00 to 7.85 and electrical conductivity from 4.0 to 6.10. Various salt concentrations were high. At 18 months old the species that were doing well were: Prosopis juliflora, Acacia nilotica, Terminalia arjuna, Syzygium cumini, Albizia lebbek, Pongamia pinnata, Cassia auriculata, Adhatoda vasica and Cassia siamea.

HYDRUS Simulation of Sustainable Brackish Water Irrigation in a Winter Wheat-Summer Maize Rotation System in the North China Plain

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Kangkang He

2017-07-01

Full Text Available Freshwater resources in the North China Plain (NCP are near depletion due to the unceasing overexploitation of deep groundwater, by far the most significant source of freshwater in the region. To deal with the deepening freshwater crisis, brackish water (rich but largely unused water in agriculture is increasingly being used in irrigation in the region. However, inappropriate irrigation with brackish water could lead to soil salinization and cropland degradation. To evaluate such negative impacts, the HYDRUS-1D model was used to simulate soil salt transport and accumulation under 15 years of irrigation with brackish water. The irrigation scenarios included brackish water irrigation during the wintering and jointing stages of winter wheat and then freshwater irrigation just before the sowing of summer maize. Freshwater irrigation was done to leach out soil salts, which is particularly vital in dry years. For the littoral region of the plain, HYDRUS-ID was used to simulate the irrigated cropping system stated above for a total period of 15 years. The results showed that it was feasible to use brackish water twice in one year, provided freshwater irrigation was performed before sowing summer maize. Freshwater irrigation, in conjunction with precipitation, leached out soil salts from the 100 cm root-zone depth. The maximum salt accumulation was in the 160–220 cm soil layer, which ensured that root-zone soil was free of restrictive salinity for crop growth. Precipitation was a critical determinant of the rate and depth leaching of soil salt. Heavy rainfall (>100 mm caused significant leaching of soluble salts in the 0–200 cm soil profile. Salt concentration under brackish water irrigation had no significant effect on the variations in the trend of soil salt transport in the soil profile. The variations of soil salinity were mainly affected by hydrological year type, for which the buried depth of soil salt was higher in wet years than in dry years

High pressure membrane foulants of seawater, brackish water and river water: Origin assessed by sugar and bacteriohopanepolyol signatures

KAUST Repository

Mondamert, Leslie

2011-01-01

The present work aimed to study the origin of foulant material recovered on membranes used in water treatment. Firstly, sugar signatures were assessed from the monosaccharide composition. As results were not conclusive, a statistical approach using discriminant analysis was applied to the sugar data set in order to predict the origin of the foulant material. Three groups of various origins (algal, microbial, continental dissolved organic matter) were used as sugar references for the prediction. The results of the computation showed that the origin of reverse osmosis (RO) seawater foulant material is influenced by both the location of the water sources and the season. RO brackish water and nanofiltration river water foulant materials had a terrestrial origin. Secondly, bacteriohopanepolyol signatures indicated that RO seawater foulant material had a marine signature, RO brackish water foulant material had both a marine and a terrestrial origin and the nanofiltration river water foulant material contained only a terrestrial signature. © 2011 Taylor & Francis.

Delineating fresh water and brackish water aquifers by GIS and groundwater quality data

International Nuclear Information System (INIS)

Yasin, M.; Latif, M.

2007-01-01

This study was conducted in the Mona project area, Bhalwal, district Sargodha to delineate fresh water and brackish water aquifers by GIS (Geographic Information System) and historic groundwater quality data of 138 deep tube wells installed in the study area. The groundwater quality zonations were made by overlapping maps of TDS (Total Dissolved Solids), SAR (Sodium Adsorption Ratio) and RSC (Residual Sodium Carbonate). Seven zones of groundwater quality consisting of good, marginal, hazardous and their combinations were identified. The results indicated redistribution of salts in the aquifer and rise in water table in some parts of the study area from 1965-1997. (author)

Larval development of Aedes aegypti and Aedes albopictus in peri-urban brackish water and its implications for transmission of arboviral diseases.

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Ranjan Ramasamy

2011-11-01

Full Text Available Aedes aegypti (Linnaeus and Aedes albopictus Skuse mosquitoes transmit serious human arboviral diseases including yellow fever, dengue and chikungunya in many tropical and sub-tropical countries. Females of the two species have adapted to undergo preimaginal development in natural or artificial collections of freshwater near human habitations and feed on human blood. While there is an effective vaccine against yellow fever, the control of dengue and chikungunya is mainly dependent on reducing freshwater preimaginal development habitats of the two vectors. We show here that Ae. aegypti and Ae. albopictus lay eggs and their larvae survive to emerge as adults in brackish water (water with 30 ppt salt are termed fresh, brackish and saline respectively. Brackish water with salinity of 2 to 15 ppt in discarded plastic and glass containers, abandoned fishing boats and unused wells in coastal peri-urban environment were found to contain Ae. aegypti and Ae. albopictus larvae. Relatively high incidence of dengue in Jaffna city, Sri Lanka was observed in the vicinity of brackish water habitats containing Ae. aegypti larvae. These observations raise the possibility that brackish water-adapted Ae. aegypti and Ae. albopictus may play a hitherto unrecognized role in transmitting dengue, chikungunya and yellow fever in coastal urban areas. National and international health authorities therefore need to take the findings into consideration and extend their vector control efforts, which are presently focused on urban freshwater habitats, to include brackish water larval development habitats.

GPR capabilities for ice thickness sampling of low salinity ice and for detecting oil in ice

Energy Technology Data Exchange (ETDEWEB)

Lalumiere, Louis [Sensors by Design Ltd. (Canada)

2011-07-01

This report discusses the performance and capabilities test of two airborne ground-penetrating radar (GPR) systems of the Bedford Institute of Oceanography (BIO), Noggin 1000 and Noggin 500, for monitoring low salinity snow and ice properties which was used to measure the thickness of brackish ice on Lake Melville in Labrador and on a tidal river in Prince Edward Island. The work of other researchers is documented and the measurement techniques proposed are compared to the actual GPR approach. Different plots of GPR data taken over snow and freshwater ice and over ice with changing salinity are discussed. An interpretation of brackish ice GPR plots done by the Noggin 1000 and Noggin 500 systems is given based on resolution criterion. Additionally, the capability of the BIO helicopter-borne GPR to detect oil-in-ice has been also investigated, and an opinion on the likelihood of the success of GPR as an oil-in-ice detector is given.

Effects of thermal discharges on the seasonal patterns of nutrient concentrations in brackish water

International Nuclear Information System (INIS)

Nitchals, D.

1985-05-01

Massiv quantities of water are used in power plant cooling systems, especially nuclear power plants, and are often returned to the donor ecosystem at significantly elevated temperatures. Few studies of the environmental effects of such a situation have looked extensively at the effects on nutrients in the water. The present study examined the effects of cooling water discharges from a nuclear power plant on the seasonal nutrient patterns within and outside a brackish water, research artificial lake, the 0.9 km 2 Biotest Basin on Sweden's east coast. The lack of ice cover in winter is the most apparent effect. In a portion of the lake with a relatively long water residence time, on the order of a few days, the vernal nutrient depletion of phosphate, nitrate, and nitrite apparently began sooner than outside the lake. Benthic influence on nutrient concentrations in the free water mass may be very significant in coastal areas receiving heat inputs. This study's data apparently support the conclusion by other researchers that phosphorus may be the nutrient limiting algal growth in the spring in this area of the central Baltic Sea. Determination of a nutrient budget for the Basin was unachievable because inlet and outlet nutrient concentrations were insufficiently different to override experimental variation. Implications for management of heat inputs to coastal ecosystems include avoidance of areas with high nutrient content, rich organic sediment, or poor flushing. (author)

COMPOSITIONAL PROPERTIES OF THREE FRESHWATER CARP SPECIES GROWN IN BRACKISH WATER

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Muhammad Ismail Chughtai

2015-06-01

Full Text Available Three freshwater fish species viz. Labeo rohita, Cirrhinus mrigala and Gibelion catla, grown in brackish water ponds were analyzed for compositional properties to assess the potential of this habitat to produce nutritionally adequate fish for human consumption. Overall, the unsaturated fatty acids were lower in L. rohita (46.6% than saturated fatty acids; while in C. mrigala and G. catla, the unsaturated fatty acids were 50.4% and 58.2%, respectively. The most abundant saturated fatty acid in examined species was palmitic acid (C16:0, 23.7 to 34.1%; mono-unsaturated fatty acid was oleic acid (C18:1 19.6 to 31.7% and poly-unsaturated fatty acid linoleic acid (C18:2 9.46 to 13.3%. A reasonable amount of essential fatty acids ω-3 (5.80 to 9.26% and ω-6 (9.46 to 13.3% was also found in these species while growing in brackish water on salt tolerant forages like Leptochloa fusca, Brachiaria mutica and Kochia indica as supplemental feed. The ω-3/ω-6 ratio was calculated as 0.46, 0.80 and 0.69 in L. rohita, C. mrigala and G. catla, respectively. The maximum EPA (eicosapentaenoic acid, C20:5 was observed in C. mrigala (2.23%, followed by G. catla (1.62% and L. rohita (0.98%. While the DHA (docosahexanenoic acids, C22:6 was found maximum in G. catla (1.97% and minimum in C. mrigala (0.95%. The results of body composition indicated that L. rohita found maximum protein contents (19.2% with minimum total fats (1.28% while C. mrigala found maximum total fats (2.11% but minimum protein contents (18.3%. Overall results indicated that the Indian carps grown in brackish water have comparable chemical composition and nutritive value with the same species grown in freshwater medium.

The Energy-Water Nexus: Spatially-Resolved Analysis of the Potential for Desalinating Brackish Groundwater by Use of Solar Energy

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Jill B. Kjellsson

2015-06-01

Full Text Available This research looks at coupling desalination with renewable energy sources to create a high-value product (treated water from two low value resources (brackish groundwater and intermittent solar energy. Desalination of brackish groundwater is already being considered as a potential new water supply in Texas. This research uses Texas as a testbed for spatially-resolved analysis techniques while considering depth to brackish groundwater, water quality, and solar radiation across Texas to determine the locations with the best potential for integrating solar energy with brackish groundwater desalination. The framework presented herein can be useful for policymakers, regional planners, and project developers as they consider where to site desalination facilities coupled with solar photovoltaics. Results suggest that the northwestern region of Texas—with abundant sunshine and groundwater at relatively shallow depths and low salinity in areas with freshwater scarcity—has the highest potential for solar powered desalination. The range in capacity for solar photovoltaic powered reverse osmosis desalination was found to be 1.56 × 10—6 to 2.93 × 10—5 cubic meters of water per second per square meter of solar panel (m3/s/m2.

Evidence of Atlantic salmon Salmo salar fry movement between fresh water and a brackish environment.

Science.gov (United States)

Taal, I; Rohtla, M; Saks, L; Svirgsden, R; Kesler, M; Matetski, L; Vetemaa, M

2017-08-01

This study reports descent of Atlantic salmon Salmo salar fry from their natal streams to brackish waters of the Baltic Sea and their use of this environment as an alternative rearing habitat before ascending back to freshwater streams. To the authors' knowledge, residency in a brackish environment has not previously been demonstrated in S. salar fry. Recruitment success and evolutionary significance of this alternative life-history strategy are presently not known. © 2017 The Fisheries Society of the British Isles.

Brackish groundwater and its potential to augment freshwater supplies

Science.gov (United States)

Stanton, Jennifer S.; Dennehy, Kevin F.

2017-07-18

Secure, reliable, and sustainable water resources are fundamental to the Nation’s food production, energy independence, and ecological and human health and well-being. Indications are that at any given time, water resources are under stress in selected parts of the country. The large-scale development of groundwater resources has caused declines in the amount of groundwater in storage and declines in discharges to surface water bodies (Reilly and others, 2008). Water supply in some regions, particularly in arid and semiarid regions, is not adequate to meet demand, and severe drought intensifies the stresses affecting water resources (National Drought Mitigation Center, the U.S. Department of Agriculture, and the National Oceanic and Atmospheric Association, 2015). If these drought conditions continue, water shortages could adversely affect the human condition and threaten environmental flows necessary to maintain ecosystem health.In support of the national census of water resources, the U.S. Geological Survey (USGS) completed the national brackish groundwater assessment to provide updated information about brackish groundwater as a potential resource to augment or replace freshwater supplies (Stanton and others, 2017). Study objectives were to consolidate available data into a comprehensive database of brackish groundwater resources in the United States and to produce a summary report highlighting the distribution, physical and chemical characteristics, and use of brackish groundwater resources. This assessment was authorized by section 9507 of the Omnibus Public Land Management Act of 2009 (42 U.S.C. 10367), passed by Congress in March 2009. Before this assessment, the last national brackish groundwater compilation was completed in the mid-1960s (Feth, 1965). Since that time, substantially more hydrologic and geochemical data have been collected and now can be used to improve the understanding of the Nation’s brackish groundwater resources.

In situ measured elimination of Vibrio cholerae from brackish water.

Science.gov (United States)

Pérez, María Elena Martínez; Macek, Miroslav; Galván, María Teresa Castro

2004-01-01

In situ elimination of fluorescently labelled Vibrio cholerae (FLB) was measured in two saline water bodies in Mexico: in a brackish water lagoon, Mecoacán (Gulf of Mexico; State of Tabasco) and an athalassohaline lake, Alchichica (State of Puebla). Disappearance rates of fluorescently labelled V. cholera O1 showed that they were eliminated from the environment at an average rate of 32% and 63%/day, respectively (based on the bacterial standing stocks). The indirect immunofluorescence method confirmed the presence of V. cholerae O1 in the lagoon. However, the elimination of FLB was not directly related either to the presence or absence of the bacterium in the water body or to the phytoplankton concentration.

Feasibility study of white shrimp, Litopenaeus vannamei, culture in earthen ponds using brackish water of the Caspian Sea

OpenAIRE

Farabi, S.M.V.; Salehi, A.A.; Pourgholam, R.; Ghanei Tehrani, M.

2016-01-01

Litopenaeus vannamei (Boone, 1931) post-larvae 12 were obtained from Bushehr province and reared at the Caspian Sea Ecological Research Institute (Mazandaran, Iran) in summer 2012 using brackish water of the Caspian Sea. Prior to start of the experiment, post-larvae were gradually adapted to brackish water. The shrimp was stocked in a 1000 m2 earthen pond with a stocking density of 31 individual/m2. The earthen pond was in quarantine without discharge valve. During the rearing period, there w...

MINERAL NUTRITION OF CRISPHEAD LETTUCE GROWN IN A HYDROPONIC SYSTEM WITH BRACKISH WATER

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HAMMADY RAMALHO E SOARES

2016-01-01

Full Text Available Water availability in the Brazilian semiarid is restricted and often the only water source available has high salt concentrations. Hydroponics allows using these waters for production of various crops, including vegetables, however, the water salinity can cause nutritional disorders. Thus, two experiments were conducted in a greenhouse at the Department of Agricultural Engineering of the Federal Rural University of Pernambuco, to evaluate the effects of salinity on the mineral nutrition of crisphead lettuce, cultivar Taina, in a hydroponic system (Nutrient Film Technique, using brackish water in the nutrient solution, which was prepared by adding NaCl to the local water (0.2 dS m-1. A randomized blocks experimental design was used in both experiments. The treatments consisted of water of different salinity levels (0.2, 1.2, 2.2, 3.2, 4.2 and 5.2 dS m-1 with four replications, totaling 24 plots for each experiment. The water added to compensate for the water-depth loss due to evapotranspiration (WCET was the brackish water of each treatment in Experiment I and the local water without modifications in Experiment II. The increase in the salinity of the water used for the nutrient solution preparation reduced the foliar phosphorus and potassium contents and increased the chloride and sodium contents, regardless of the WCET. Foliar nitrogen, calcium, magnesium and sulfur contents were not affected by increasing the water salinity used for the nutrient solution preparation.

REMOVAL OF NATURAL ORGANIC MATTER USING ELECTROCOAGULATION AS A FIRST STEP FOR DESALINATION OF BRACKISH WATER

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Wasinton Simanjuntak

2011-07-01

Full Text Available In the present study, electrocoagulation method was employed to remove natural organic matter from brackish water. This study explores the potential of brackish water as a source of potable water. Two electrochemical variables, potential and contact time, were tested to determine their effect on the treatment efficiency defined in terms of the reduction of the absorbance at the wavelength of 254 nm (A254. Both potential and contact time were found to influence the removal efficiency of the method, and the best result was obtained from the experiment using the potential of 8 V and contact time of 60 min, resulting in 69.5% reduction of the absorbance. Very clean treated water was produced with much lower conductivity (12.06 mS/cm as compared to that obtained for the sea water sample from a location near to the sampling site (133.9 mS/cm.

Brackish groundwater as an alternative source of cooling water for nuclear power plants in Israel

International Nuclear Information System (INIS)

Arad, A.; Olshina, A.

1984-01-01

The western Negev is being considered as a potential site for the location of a nuclear powerplant. Since this part of Israel has no surface water, the only alternatives for cooling water are piped-in water, Mediterranean water and local, brackish groundwater. The Judea Group aquifer was examined for its potential to provide the required amount of cooling water over the lifetime of the plant, without causing a drastic lowering of the regional water table. The salinity of the water tends to increase from east to west. Flow within the aquifer is in the direction of Beer Sheva, where the extraction rate is 32 to 35 million cu m/yr. This has resulted in a salinity creep of 5-10 mg Cl per year in the Beer Sheva area, which poses a danger of deterioration of its water supply in the long term. Given the assumed range of aquifer properties, extraction of brackish water for cooling purposes will not result in large changes in the regional water table. Exploitation of the more saline water to the southwest of Beer Sheva could preserve the quality of Beer Sheva's water supply, at the expense of an increase in the depth from which it must be pumped. 2 references, 7 figures, 2 tables

Desalination of brackish groundwater and concentrate disposal by deep well injection

NARCIS (Netherlands)

Wolthek, N.; Raat, K.; Ruijter, J.A.; Kemperman, Antonius J.B.; Oosterhof, A.

2013-01-01

In the province of Friesland (in the Northern part of The Netherlands), problems have arisen with the abstraction of fresh groundwater due to salinization of wells by upcoming of brackish water. A solution to this problem is to intercept (abstract) the upcoming brackish water, desalinate it with a

Experimental provocation of 'ice-cream headache' by ice cubes and ice water.

Science.gov (United States)

Mages, Stephan; Hensel, Ole; Zierz, Antonia Maria; Kraya, Torsten; Zierz, Stephan

2017-04-01

Background There are various studies on experimentally provoked 'ice-cream headache' or 'headache attributed to ingestion or inhalation of a cold stimulus' (HICS) using different provocation protocols. The aim of this study was to compare two provocation protocols. Methods Ice cubes pressed to the palate and fast ingestion of ice water were used to provoke HICS and clinical features were compared. Results The ice-water stimulus provoked HICS significantly more often than the ice-cube stimulus (9/77 vs. 39/77). Ice-water-provoked HICS had a significantly shorter latency (median 15 s, range 4-97 s vs. median 68 s, range 27-96 s). There was no difference in pain localisation. Character after ice-cube stimulation was predominantly described as pressing and after ice-water stimulation as stabbing. A second HICS followed in 10/39 (26%) of the headaches provoked by ice water. Lacrimation occurred significantly more often in volunteers with than in those without HICS. Discussion HICS provoked by ice water was more frequent, had a shorter latency, different pain character and higher pain intensity than HICS provoked by ice cubes. The finding of two subsequent HICS attacks in the same volunteers supports the notion that two types of HICS exist. Lacrimation during HICS indicates involvement of the trigeminal-autonomic reflex.

Radiological study of brackish and fresh water food samples in Lagos and Ondo states, southwestern Nigeria

International Nuclear Information System (INIS)

Ojo, T.J.; Ojo, O.C.

2007-01-01

Measurement of the average radioactivity concentration in brackish and fresh water food samples in Lagos and Ondo States of Nigeria was carried out using a very sensitive gamma spectroscopic system consisting of a 76 mm x 76 mm Nal (TI) scintillation detector coupled to a computerized ACCUSPEC installation. All the radionuclide detected are traceable to the naturally occurring 4 ''0K and ''2''3''2Th. The average concentrations of ''2''3''8U and ''2''3''2Th were found to be higher in brackish water food samples, 50.92±7.04 Bq/kg and 24.60± 6.47 Bq/kg respectively. The average concentration of ''4''0K was found to be higher in food samples got from freshwater, 738.94±84.81Bq/kg

Potabilization of brackish water by electrodialysis. Study of natural samples with a laboratory unit

International Nuclear Information System (INIS)

Sainz Sastre, J. A.; Alonso-Lopez, J.

1972-01-01

Potabilization of brackish waters from Ciguela (Toledo) and Riansares (Toledo) rivers, and from wells 1 and 2 at Torre Pacheco (Murcia), as well as of sea water diluted to 5,000 ppm has been studied in process conditions optimized from experiments with synthetic solutions. The study includes: removal of suspended and organic matter, determination of limit current density, power requirements, ion selectivity and daily maximum output of the unit. (Author) 8 refs

87Sr/86Sr as a quantitative geochemical proxy for 14C reservoir age in dynamic, brackish waters: assessing applicability and quantifying uncertainties.

Science.gov (United States)

Lougheed, Bryan; van der Lubbe, Jeroen; Davies, Gareth

2016-04-01

Accurate geochronologies are crucial for reconstructing the sensitivity of brackish and estuarine environments to rapidly changing past external impacts. A common geochronological method used for such studies is radiocarbon (14C) dating, but its application in brackish environments is severely limited by an inability to quantify spatiotemporal variations in 14C reservoir age, or R(t), due to dynamic interplay between river runoff and marine water. Additionally, old carbon effects and species-specific behavioural processes also influence 14C ages. Using the world's largest brackish water body (the estuarine Baltic Sea) as a test-bed, combined with a comprehensive approach that objectively excludes both old carbon and species-specific effects, we demonstrate that it is possible to use 87Sr/86Sr ratios to quantify R(t) in ubiquitous mollusc shell material, leading to almost one order of magnitude increase in Baltic Sea 14C geochronological precision over the current state-of-the-art. We propose that this novel proxy method can be developed for other brackish water bodies worldwide, thereby improving geochronological control in these climate sensitive, near-coastal environments.

Electrodialytic desalination of brackish water: determination of optimal experimental parameters using full factorial design

Science.gov (United States)

Gmar, Soumaya; Helali, Nawel; Boubakri, Ali; Sayadi, Ilhem Ben Salah; Tlili, Mohamed; Amor, Mohamed Ben

2017-12-01

The aim of this work is to study the desalination of brackish water by electrodialysis (ED). A two level-three factor (23) full factorial design methodology was used to investigate the influence of different physicochemical parameters on the demineralization rate (DR) and the specific power consumption (SPC). Statistical design determines factors which have the important effects on ED performance and studies all interactions between the considered parameters. Three significant factors were used including applied potential, salt concentration and flow rate. The experimental results and statistical analysis show that applied potential and salt concentration are the main effect for DR as well as for SPC. The effect of interaction between applied potential and salt concentration was observed for SPC. A maximum value of 82.24% was obtained for DR under optimum conditions and the best value of SPC obtained was 5.64 Wh L-1. Empirical regression models were also obtained and used to predict the DR and the SPC profiles with satisfactory results. The process was applied for the treatment of real brackish water using the optimal parameters.

PRODUCTION COMPONENTS OF Vigna unguiculata (L. Walp IRRIGATED WITH BRACKISH WATER UNDER DIFFERENT LEACHING FRACTIONS

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JOSÉ FRANCISCO DE CARVALHO

2016-01-01

Full Text Available The objective of this work was to evaluate the production components of cowpea ( Vigna unguiculata L. Walp subjected to irrigation with brackish water and different leaching fractions. The experiment was conducted in a lysimeter system of the Department of Agricultural Engineering of the Federal Rural University of Pernambuco, Recife campus. The treatments, consisting of two water salinity levels (ECw (1.2 and 3.3 dS m - 1 and five leaching fractions (0, 5, 10, 15 and 20%, were evaluated using a completely randomized design in a 2x5 factorial arrangement with four replications. The variables evaluated were: number of pods per plant, 100 - grain weight, number of grains per pod, grain and shoot dry weight, grain yield and harvest index. The soil salinity increased with increasing salinity of the water used for irrigation, and reduced with increasing leaching fraction. The salinity of the water used for irrigation influenced only the variables number of pods per plant and grain yield. The estimated leaching fractions of 9.1% and 9.6% inhibited the damage caused by salinity on the number of pods per plant and grain yield, respectively. Therefore, the production of V. unguiculata irrigated with brackish water, leaching salts from the plant root environment, is possible under the conditions evaluated.

Ratio of 210Po and 210Pb in fresh, brackish and saline water in Kuala Selangor river

International Nuclear Information System (INIS)

Tan Chin Siang; Che Abdul Rahim Mohamed; Zaharuddin Ahmad

2007-01-01

Sediment cores were carried out from Kuala Selangor river to amine sea water via coastal and brackish water ambient. Sample size fraction with size less than 125 μm was spiked with tracer 209 Po and leached with mix concentrated nitric acid, perchloric acid, hydrogen peroxide, hydrochloric acid and mineralized with 50 ml of 0.5M HCl. The sample solution was used for spontaneously deposit polonium on a silver disk at 80-85 degree Celsius and measured with the Alpha Spectrometry. The distribution of two radionuclides especially 210 Po, 210 Pb and 210 po/ 210 Pb were useful in identifying the origin of 210 Po. Ratio values of 210 Po/ 210 Pb in the freshwater, brackish water and saline water were 3.3459, 5.8385 and 2.9831, respectively. From the high ratio of 210 Po/ 210 Pb, the widespread occurrence of excess 210 Po in Kuala Selangor river water may came from the atmosphere sources such as stratospheric aerosols, sea spray of the surface micro layer and bio-volatile 210 Po organism from productive species. (author)

Variation in Lateral Plate Quality in Threespine Stickleback from Fresh, Brackish and Marine Water: A Micro-Computed Tomography Study.

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Elisabeth Wiig

Full Text Available It is important to understand the drivers leading to adaptive phenotypic diversity within and among species. The threespine stickleback (Gasterosteus aculeatus has become a model system for investigating the genetic and phenotypic responses during repeated colonization of fresh waters from the original marine habitat. During the freshwater colonization process there has been a recurrent and parallel reduction in the number of lateral bone plates, making it a suitable system for studying adaptability and parallel evolution.The aim of this study was to investigate an alternative evolutionary path of lateral plate reduction, where lateral plates are reduced in size rather than number.A total of 72 threespine stickleback individuals from freshwater (n = 54, brackish water (n = 27 and marine water (n = 9 were analysed using microcomputed tomography (μCT to determine variation in size, thickness and structure of the lateral plates. Furthermore, whole-body bone volume, and bone volume, bone surface and porosity of lateral plate number 4 were quantified in all specimens from each environment.The results showed a significant difference in plate size (area and volume among populations, where threespine stickleback from polymorphic freshwater and brackish water populations displayed lateral plates reduced in size (area and volume compared to marine stickleback.Reduction of lateral plates in threespine stickleback in fresh and brackish water occurs by both plate loss and reduction in plate size (area and volume.

Effect of combination dope composition and evaporation time on the separation performance of cellulose acetate membrane for demak brackish water treatment

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Kusworo Tutuk Djoko

2017-01-01

Full Text Available The coastal areas in Indonesia often have a problem of clean water lack, because the water is classified as brackish water. Therefore, this research investigated the fabrication of CA membranes using phase inversion method for brackish water treatment. Investigation was conducted to study the effect of combination dope composition and evaporation time on separation performance and morphology of the memrbane. Membrane was fabricated by dry-wet phase inversion technique with variation of polymer concentration 17, 18 and 20 wt% in the total solid and evaporation time of 5, 10 and 15 seconds, respectively. The asymmetric membranes were characterized by permeability test through rejection and flux measurements using brackish water as feed. The experimental results from SEM images analysis showed that all the membranes have a thin small porous layer and thicker sub-structure of larger porous layer formed asymmetric membrane. Moreover, the greater polymer concentration is resulting smaller pore size and smaller membrane porosity. The longer evaporation time was also resulted in denser membrane active layer. The best membrane performance was observed at the composition of 20 wt% CA polymer, 1 wt % polyethylene glycol with the solvent evaporation time of 15 seconds.

Tritium concentration in fresh, brackish and sea-water samples in Rokkasho-Village, Japan, bordered by nuclear fuel cycle facilities

International Nuclear Information System (INIS)

Ueda, S.; Kakiuchi, H.; Kondo, K.; Inaba, J.

2006-01-01

In order to identify the concentration of tritium ( 3 H) in areas of fresh, brackish and sea water, bordered by nuclear fuel facilities at Rokkasho-Village, Aomori, Japan, water samples were collected from 2001 to 2004 at six points in those areas. Concentration ranges of tritium in fresh river water, brackish lake and seawater samples were 0.60 to 1.1 Bq x l -1 (mean value 0.79 Bq x l -1 ), 0.20 to 0.87 Bq x l -1 (mean value 0.41 Bq x l -1 ), and 0.08 to 0.25 Bq x l -1 (mean value 0.15 Bq x l -1 ), respectively. Relationships between tritium concentrations and salinity in the samples showed a clear negative correlation. Moreover, the seasonal variation of tritium in water from Rokkasho-Village was high in spring and low in fall. (author)

Brackish and seawater desalination for process and demineralised water production for large power plants in the North Sea region

Energy Technology Data Exchange (ETDEWEB)

Nagel, Rolf [Hager + Elsaesser GmbH, Stuttgart (Germany); Brinkmann, Juergen [RWE Technology GmbH, Essen (Germany)

2010-06-15

Large power plants for power generation from fossil fuels are constantly being optimised in order to improve their efficiency. One element of the overall considerations is once-through cooling with brackish or seawater on sites near the sea. In addition to the higher overall efficiency, such sites - thanks to their connection to ocean shipping - also offer infrastructural advantages regarding fuel supply and residual material disposal compared to inland sites. Because the cooling water intake and discharge structures have to be built anyway, they lend themselves to also producing the process and demineralised water from the brackish or seawater. In this case, the use of fresh or drinking water as resources can be minimised. In the following report, we present a pilot study using ultrafiltration and reverse osmosis on a North Sea site with raw water intake from a seaport basin. (orig.)

Adaptation, growth and survival of tilapia (Oreochromis niloticus) in Bafgh brackish water

OpenAIRE

Sarsangi, A.H.; Mohammadi, M.; Mashaii, N.; Rajabipou, F.; Bitaraf, A.; Askari, H.M.; Moazedi, J.; Nezamabadi, H.; Hosseinzadeh Sahafi, H.

2012-01-01

An experiment was conducted to evaluate the possibility of adaptation, growth and survival of Nile tilapia (Oreochromis niloticus) with 0.3g initial weight and red tilapia (Oreochromis sp.) with 0.7g initial weight in underground brackish water. Fry of Nile tilapia and red tilapia imported from Indonesia and after passing larviculture (25g) were examined separately in fiber glass tank by two replicate. Fish were fed at a restricted feeding program according to standard table during the light ...

Further investigations of aquaponics using brackish water resources of the Negev desert

Directory of Open Access Journals (Sweden)

Samuel Appelbaum

2016-10-01

Full Text Available Outdoor, floating raft aquaponic systems using the brackish waters of the Negev Desert in Israel and a fresh water control are described. 7 m2 of vegetables and herbs were grown in each recirculating system with Tilapia sp. fish. Plant growth was excellent for species such as celery, Swiss chard, spring onions and watercress, and fish health and growth were good. Growth rates for fish were, however, low, with an upper limit of 1.1 g per day and would have increased with ad libitum feeding. Water quality was well controlled, and iron chelate was added to correct chlorosis problems. Leafy growth was very good, but fruiting could be improved with the addition of potassium (K and other micronutrients.

Updated numerical model with uncertainty assessment of 1950-56 drought conditions on brackish-water movement within the Edwards aquifer, San Antonio, Texas

Science.gov (United States)

Brakefield, Linzy K.; White, Jeremy T.; Houston, Natalie A.; Thomas, Jonathan V.

2015-01-01

In 2010, the U.S. Geological Survey, in cooperation with the San Antonio Water System, began a study to assess the brackish-water movement within the Edwards aquifer (more specifically the potential for brackish-water encroachment into wells near the interface between the freshwater and brackish-water transition zones, referred to in this report as the transition-zone interface) and effects on spring discharge at Comal and San Marcos Springs under drought conditions using a numerical model. The quantitative targets of this study are to predict the effects of higher-than-average groundwater withdrawals from wells and drought-of-record rainfall conditions of 1950–56 on (1) dissolved-solids concentration changes at production wells near the transition-zone interface, (2) total spring discharge at Comal and San Marcos Springs, and (3) the groundwater head (head) at Bexar County index well J-17. The predictions of interest, and the parameters implemented into the model, were evaluated to quantify their uncertainty so the results of the predictions could be presented in terms of a 95-percent credible interval.

A comparison of individual doses for continuous annual unit releases of tritium and activation products into brackish water and lake-river ecosystems

Energy Technology Data Exchange (ETDEWEB)

Edlund, O.; Aquilonius, K.

1995-12-31

The annual effective doses to critical group from potential unit releases of tritium and activation products (32 nuclides) from a hypothetical fusion reactor into two aquatic environments, one with brackish water and the other with fresh water, are assessed. Unit continuous releases (1 Bq/year during 50 years) for each relevant activation product are analyzed, and the effective dose rate is calculated for each nuclide. The transfer of released activity is simulated by compartment models using first-order linear differential equations for the transport. The rate constants for the brackish-water ecosystem are based on measurements. Four exposure pathways are considered in the brackish water system, the Tvaeren Bay, (a) consumption of fish, (b) consumption of milk, (c) consumption of meat, and (d) exposure from swimming. For the freshwater system, five additional pathways are considered, namely consumption of (e) water, (f) vegetables, (g) cereals, and (h) root vegetables and (i) external exposure from contaminated ground. The paper presents the compartment models used and a description of how the exposure pathways are treated, especially the pathways via food consumption. The dominating exposure pathways are for most of the nuclides consumption of fish and water. For Ag-isotopes other exposure pathways, such as ground-shine, cereals and meat, are of importance. The results of this study show that individual annual effective doses attributed to unit releases of most of the nuclides to the lake-river system become 1.3-60 times lower than those released to the brackish-water system. The niobium isotopes, however, give a factor 2.5-4.8 higher dose. The reason to that is that the values of the bioaccumulation factor for these isotopes are higher in fresh water than in marine water. An uncertainty analysis is performed on each ecosystem and the results are obtained in the form of distributions. 38 refs, 29 tabs.

A comparison of individual doses for continuous annual unit releases of tritium and activation products into brackish water and lake-river ecosystems

International Nuclear Information System (INIS)

Edlund, O.; Aquilonius, K.

1995-01-01

The annual effective doses to critical group from potential unit releases of tritium and activation products (32 nuclides) from a hypothetical fusion reactor into two aquatic environments, one with brackish water and the other with fresh water, are assessed. Unit continuous releases (1 Bq/year during 50 years) for each relevant activation product are analyzed, and the effective dose rate is calculated for each nuclide. The transfer of released activity is simulated by compartment models using first-order linear differential equations for the transport. The rate constants for the brackish-water ecosystem are based on measurements. Four exposure pathways are considered in the brackish water system, the Tvaeren Bay, (a) consumption of fish, (b) consumption of milk, (c) consumption of meat, and (d) exposure from swimming. For the freshwater system, five additional pathways are considered, namely consumption of e) water, f) vegetables, g) cereals, and h) root vegetables and i) external exposure from contaminated ground. The paper presents the compartment models used and a description of how the exposure pathways are treated, especially the pathways via food consumption. The dominating exposure pathways are for most of the nuclides consumption of fish and water. For Ag-isotopes other exposure pathways, such as ground-shine, cereals and meat, are of importance. The results of this study show that individual annual effective doses attributed to unit releases of most of the nuclides to the lake-river system become 1.3-60 times lower than those released to the brackish-water system. The niobium isotopes, however, give a factor 2.5-4.8 higher dose. The reason to that is that the values of the bioaccumulation factor for these isotopes are higher in fresh water than in marine water. An uncertainty analysis is performed on each ecosystem and the results are obtained in the form of distributions. 38 refs, 29 tabs

A comparison of individual doses for continuous annual unit releases of tritium and activation products into brackish water and lake-river ecosystems

Energy Technology Data Exchange (ETDEWEB)

Edlund, O; Aquilonius, K

1996-12-31

The annual effective doses to critical group from potential unit releases of tritium and activation products (32 nuclides) from a hypothetical fusion reactor into two aquatic environments, one with brackish water and the other with fresh water, are assessed. Unit continuous releases (1 Bq/year during 50 years) for each relevant activation product are analyzed, and the effective dose rate is calculated for each nuclide. The transfer of released activity is simulated by compartment models using first-order linear differential equations for the transport. The rate constants for the brackish-water ecosystem are based on measurements. Four exposure pathways are considered in the brackish water system, the Tvaeren Bay, (a) consumption of fish, (b) consumption of milk, (c) consumption of meat, and (d) exposure from swimming. For the freshwater system, five additional pathways are considered, namely consumption of (e) water, (f) vegetables, (g) cereals, and (h) root vegetables and (i) external exposure from contaminated ground. The paper presents the compartment models used and a description of how the exposure pathways are treated, especially the pathways via food consumption. The dominating exposure pathways are for most of the nuclides consumption of fish and water. For Ag-isotopes other exposure pathways, such as ground-shine, cereals and meat, are of importance. The results of this study show that individual annual effective doses attributed to unit releases of most of the nuclides to the lake-river system become 1.3-60 times lower than those released to the brackish-water system. The niobium isotopes, however, give a factor 2.5-4.8 higher dose. The reason to that is that the values of the bioaccumulation factor for these isotopes are higher in fresh water than in marine water. An uncertainty analysis is performed on each ecosystem and the results are obtained in the form of distributions. 38 refs, 29 tabs.

The brackish-water bivalve Waagenoperna from the Lower Jurassic Badaowan Formation of the Junggar Basin and its palaeoenvironmental and palaeogeographic significance

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Yanhong Pan

2013-01-01

Full Text Available The brackish-water bivalve Waagenoperna Tokuyama, 1959 is reported from the Lower Jurassic Badaowan Formation at four localities, along the southern margin and western margin of the Junggar Basin. Taphonomic features recorded in the field indicate that it occurs in autochthonous or parautochthonous assemblages. The autecology of Waagenoperna therefore yields information on the palaeoenvironment of the area. The restriction of Waagenoperna to marine and brackish-water settings suggests that the sea water once reached these areas during the Sinemurian. This paper discusses the palaeogeographic implications and suggests an ingression of the sea water from the west to the western and southern part of the Junggar Basin. Additionally, the two Waagenoperna species collected from the Haojiagou section in the Junggar Basin are taxonomically documented.

Characterizing the Occurrence and Transport of Brackish Groundwater in Southwest Bangladesh

Science.gov (United States)

worland, S.; Hornberger, G. M.

2013-12-01

Bangladesh is host to the largest and the most active delta system in the world. The morphology of the southern part of the country is characterized by low lying deltaic plains partitioned by the distributary networks of the Ganges, Brahmaputra and Meghna river systems. Much of the tidal mangrove forest ecosystem of the lower delta has been converted into poldered islands that sustain shrimp farming and rice production. The polder inhabitants depend on shallow groundwater as a primary source for drinking water and sanitation. Understanding the origin and hydrologic controls on the distribution of the brackish water and freshwater on the polder is a necessary step to ensuring a sustainable and potable freshwater source for drinking and irrigation. Preliminary sampling from shallow tube wells on Polder 32 in southwest Bangladesh suggests sporadic lateral apportioning of fresh water in the primarily brackish aquifer. This research characterizes the occurrence, transport and fate of the brackish groundwater through a combination of 3H and 14C dating, geochemical signatures, subsurface mapping using inversions from electromagnetic induction, and a 1D finite difference model and a 2D finite element model. The geochemical analysis and radiometric dating suggest that the salt water originates from paleo-brackish estuarine water deposited ~5000 years ago along with the sediments that compose the shallow aquifer. Inversions of electromagnetic survey data show potential freshwater recharge areas where the clay cap pinches out. The finite difference model demonstrates that recharge from the distributary channels is unlikely due to the low transmissivity of the clay channel beds. The finite element model gives reasonable estimates of the flushing rates of the connate brackish water beneath the polder. Inversion of electromagnetic data from a two hundred meter transect taken on Polder 32 Head gradient and groundwater flow vectors for fixed head boundary conditions across Polder

Turbulent heat exchange between water and ice at an evolving ice-water interface

Science.gov (United States)

Ramudu, Eshwan; Hirsh, Benjamin Henry; Olson, Peter; Gnanadesikan, Anand

2016-07-01

We conduct laboratory experiments on the time evolution of an ice layer cooled from below and subjected to a turbulent shear flow of warm water from above. Our study is motivated by observations of warm water intrusion into the ocean cavity under Antarctic ice shelves, accelerating the melting of their basal surfaces. The strength of the applied turbulent shear flow in our experiments is represented in terms of its Reynolds number $\\textit{Re}$, which is varied over the range $2.0\\times10^3 \\le \\textit{Re} \\le 1.0\\times10^4$. Depending on the water temperature, partial transient melting of the ice occurs at the lower end of this range of $\\textit{Re}$ and complete transient melting of the ice occurs at the higher end. Following these episodes of transient melting, the ice reforms at a rate that is independent of $\\textit{Re}$. We fit our experimental measurements of ice thickness and temperature to a one-dimensional model for the evolution of the ice thickness in which the turbulent heat transfer is parameterized in terms of the friction velocity of the shear flow. The melting mechanism we investigate in our experiments can easily account for the basal melting rate of Pine Island Glacier ice shelf inferred from observations.

Cytological comparison of gill chloride cells and blood serum ion concentrations in kutum (Rutilus frisii kutum spawners from brackish (Caspian Sea and fresh water (Khoshkrood River environments

Directory of Open Access Journals (Sweden)

Ghahremanzadeh Zahra

2014-09-01

Full Text Available The size and number of chloride cells and serum ion concentrations in kutum, Rutillus frisii kutum Nordman, from brackish (Caspian Sea and fresh water (Khoshkrood River environments were studied to gain a better understanding of osmoregulation in this species. Twenty mature kutum specimens were collected from the Caspian Sea (Anzali coasts, 8.49 ppt salinity and 12.4°C temperature and 20 specimens from Khoshkrood River (0.18 ppt salinity and 18°C temperature. Gill samples were analyzed histologically and concentrations of Na+, Cl- , K+, and Mg2+ ions were determined in the blood serum. Concentrations of Na+, Cl- , K+, and Mg2+ ions and osmotic pressure in mature kutum from brackish water were significantly higher than in specimens from fresh water. The average size and number of chloride cells in the fish from seawater were considerably larger than those from fresh water. The mean size of chloride cells was 6.89 ± 1.16 μm in brackish water samples and 5.1 ± 0.81 μm in river samples. The average number of chloride cells in brackish and river water samples were 16.92 and 6.57, respectively. The density and size of chloride cells increased with increases in salinity

Fecundity regulation in relation to habitat utilisation of two sympatric flounder (Platichtys flesus) populations in the brackish water Baltic Sea

DEFF Research Database (Denmark)

Nissling, Anders; Thorsen, Anders; da Silva, Filipa F.G.

2015-01-01

Two populations of flounder (Platichtys flesus) with different life history traits inhabit the brackish water Baltic Sea. Both types share feeding areas in coastal waters during summer-autumn but utilise different habitats for spawning in spring, namely offshore spawning with pelagic eggs and coa...

Studies of thermal annealing and dope composition on the enhancement of separation performance cellulose acetate membrane for brackish water treatment from Jepara

Directory of Open Access Journals (Sweden)

Tutuk Djoko Kusworo

2014-08-01

Full Text Available Membrane is an alternative technology of water treatment with filtration principle that is being widely developed and used for water treatment. The main objective of this study was to make an asymmetric membrane using cellulose acetate polymer and study the effect of additive and annealing treatment on the morphology structure and performance of cellulose acetate membranes in brackish water treatment. Asymmetric membranes for brackish water treatment were casted using a casting machine process from dope solutions containing cellulose acetates and acetone as a solvent. Membranes was prepared by phase inversion method  with variation of polyethylene glycol (PEG concentration of 1 and 5 wt% and with thermal annealing at 60 oC in 10 seconds and without thermal annealing behavior. Membrane characterization consists of calculation of membrane flux and rejection with brackish water as a feed from Jepara. The research concluded that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion method. The more added concentration of PEG will be resulted the larger pore of membrane. Meanwhile the higher temperature and the longer time of annealing treatment, the skin layer of membrane become denser. Membrane with the composition of 18 wt% cellulose acetate, 5 wt% PEG, 1 wt% distilled water, with heat treatment at temperature of 60 oC for 10 seconds is obtained optimal performance.

Ongoing niche differentiation under high gene flow in a polymorphic brackish water threespine stickleback (Gasterosteus aculeatus) population.

Science.gov (United States)

Østbye, Kjartan; Taugbøl, Annette; Ravinet, Mark; Harrod, Chris; Pettersen, Ruben Alexander; Bernatchez, Louis; Vøllestad, Leif Asbjørn

2018-02-05

Marine threespine sticklebacks colonized and adapted to brackish and freshwater environments since the last Pleistocene glacial. Throughout the Holarctic, three lateral plate morphs are observed; the low, partial and completely plated morph. We test if the three plate morphs in the brackish water Lake Engervann, Norway, differ in body size, trophic morphology (gill raker number and length), niche (stable isotopes; δ 15 N, δ 13 C, and parasites (Theristina gasterostei, Trematoda spp.)), genetic structure (microsatellites) and the lateral-plate encoding Stn382 (Ectodysplasin) gene. We examine differences temporally (autumn 2006/spring 2007) and spatially (upper/lower sections of the lake - reflecting low versus high salinity). All morphs belonged to one gene pool. The complete morph was larger than the low plated, with the partial morph intermediate. The number of lateral plates ranged 8-71, with means of 64.2 for complete, 40.3 for partial, and 14.9 for low plated morph. Stickleback δ 15 N was higher in the lower lake section, while δ 13 C was higher in the upper section. Stickleback isotopic values were greater in autumn. The low plated morph had larger variances in δ 15 N and δ 13 C than the other morphs. Sticklebacks in the upper section had more T. gasterostei than in the lower section which had more Trematoda spp. Sticklebacks had less T. gasterostei, but more Trematoda spp. in autumn than spring. Sticklebacks with few and short rakers had more T. gasterostei, while sticklebacks with longer rakers had more Trematoda. spp. Stickleback with higher δ 15 N values had more T. gasterostei, while sticklebacks with higher δ 15 N and δ 13 C values had more Trematoda spp. The low plated morph had fewer Trematoda spp. than other morphs. Trait-ecology associations may imply that the three lateral plate morphs in the brackish water lagoon of Lake Engervann are experiencing ongoing divergent selection for niche and migratory life history strategies under high gene

Development of a sensor for the detection of Escherichia coli in brackish waters

Directory of Open Access Journals (Sweden)

Mancuso Monique

2016-03-01

Full Text Available Monitoring of bacterial pathogens is important for marine environmental protection, because the presence of these microorganisms can be a serious risk for human health. For this reason, a portable sensor implemented as an electronic embedded system featuring disposable measurement cells was used to evaluate the ability and sensitivity of detection of Escherichia coli (E. coli as an indicator of fecal pollution in transitional environments and a water sample added with E. coli (102 CFU/mL was assayed. The first result obtained from the laboratory experiment seems promising for the determination of E. coli in environmental samples, though further improvements will be needed for the field application of this sensor in marine and brackish waters.

21 CFR 135.160 - Water ices.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Water ices. 135.160 Section 135.160 Food and Drugs... CONSUMPTION FROZEN DESSERTS Requirements for Specific Standardized Frozen Desserts § 135.160 Water ices. (a) Description. Water ices are the foods each of which is prepared from the same ingredients and in the same...

Export of Ice-Cavity Water from Pine Island Ice Shelf, West Antarctica

Science.gov (United States)

Thurnherr, Andreas; Jacobs, Stanley; Dutrieux, Pierre

2013-04-01

Stability of the West Antarctic Ice Sheet is sensitive to changes in melting at the bottom of floating ice shelves that form the seaward extensions of Antarctic glaciers flowing into the ocean. Not least because observations in the cavities beneath ice shelves are difficult, heat fluxes and melt rates have been inferred from oceanographic measurements obtained near the ice edge (calving fronts). Here, we report on a set of hydrographic and velocity data collected in early 2009 near the calving front of the Amundsen Sea's fast-moving and (until recently) accelerating Pine Island Glacier and its associated ice shelf. CTD profiles collected along the southern half of the meridionally-trending ice front show clear evidence for export of ice-cavity water. That water was carried in the upper ocean along the ice front by a southward current that is possibly related to a striking clockwise gyre that dominated the (summertime) upper-ocean circulation in Pine Island Bay. Signatures of ice-cavity water appear unrelated to current direction along most of the ice front, suggesting that cross-frontal exchange is dominated by temporal variability. However, repeated hydrographic and velocity measurements in a small "ice cove" at the southern end of the calving front show a persistent strong (mean velocity peaking near 0.5 ms-1) outflow of ice-cavity water in the upper 500 m. While surface features (boils) suggested upwelling from deep below the ice shelf, vertical velocity measurements reveal 1) that the mean upwelling within the confines of the cove was too weak to feed the observed outflow, and 2) that large high-frequency internal waves dominated the vertical motion of water inside the cove. These observations indicate that water exchange between the Pine Island Ice Shelf cavity and the Amundsen sea is strongly asymmetric with weak broad inflow at depth and concentrated surface-intensified outflow of melt-laden deep water at the southern edge of the calving front. The lack of

Determination of ice water path in ice-over-water cloud systems using combined MODIS and AMSR-E measurements

Science.gov (United States)

Huang, Jianping; Minnis, Patrick; Lin, Bing; Yi, Yuhong; Fan, T.-F.; Sun-Mack, Sunny; Ayers, J. K.

2006-11-01

To provide more accurate ice cloud microphysical properties, the multi-layered cloud retrieval system (MCRS) is used to retrieve ice water path (IWP) in ice-over-water cloud systems globally over oceans using combined instrument data from Aqua. The liquid water path (LWP) of lower-layer water clouds is estimated from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) measurements. The properties of the upper-level ice clouds are then derived from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements by matching simulated radiances from a two-cloud-layer radiative transfer model. The results show that the MCRS can significantly improve the accuracy and reduce the over-estimation of optical depth and IWP retrievals for ice-over-water cloud systems. The mean daytime ice cloud optical depth and IWP for overlapped ice-over-water clouds over oceans from Aqua are 7.6 and 146.4 gm-2, respectively, down from the initial single-layer retrievals of 17.3 and 322.3 gm-2. The mean IWP for actual single-layer clouds is 128.2 gm-2.

Sputtering of water ice

International Nuclear Information System (INIS)

Baragiola, R.A.; Vidal, R.A.; Svendsen, W.; Schou, J.; Shi, M.; Bahr, D.A.; Atteberrry, C.L.

2003-01-01

We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from the decay of H(2p) atoms sputtered by heavy ion impact, but not bulk ice luminescence. Radiolyzed ice does not sputter under 3.7 eV laser irradiation

Biofouling on Coated Carbon Steel in Cooling Water Cycles Using Brackish Seawater

Directory of Open Access Journals (Sweden)

Pauliina Rajala

2016-11-01

Full Text Available Water cooling utilizing natural waters is typically used for cooling large industrial facilities such as power plants. The cooling water cycles are susceptible to biofouling and scaling, which may reduce heat transfer capacity and enhance corrosion. The performance of two fouling-release coatings combined with hypochlorite treatment were studied in a power plant utilizing brackish sea water from the Baltic Sea for cooling. The effect of hypochlorite as an antifouling biocide on material performance and species composition of microfouling formed on coated surfaces was studied during the summer and autumn. Microfouling on surfaces of the studied fouling-release coatings was intensive in the cooling water cycle during the warm summer months. As in most cases in a natural water environment the fouling consisted of both inorganic fouling and biofouling. Chlorination decreased the bacterial number on the surfaces by 10–1000 fold, but the efficacy depended on the coating. In addition to decreasing the bacterial number, the chlorination also changed the microbial species composition, forming the biofilm on the surfaces of two fouling-release coatings. TeknoTar coating was proven to be more efficient in combination with the hypochlorite treatment against microfouling under these experimental conditions.

Improved aquifer characterization and the optimization of the design of brackish groundwater desalination systems

KAUST Repository

Malivaa, Robert G.

2011-07-01

Many water scarce regions possess brackish-water resources that can be desalted to provide alternative water supplies. Brackish groundwater desalination by reverse osmosis (RO) is less expensive than seawater systems because of reduced energy and pretreatment requirements and lesser volumes of concentrate that require disposal. Development of brackish groundwater wellfields include the same hydraulic issues that affect conventional freshwater wellfields. Managing well interference and prevention of adverse impacts such as land subsidence are important concerns. RO systems are designed to treat water whose composition falls within a system-specific envelope of salinities and ion concentrations. A fundamental requirement for the design of brackish groundwater RO systems is prediction of the produced water chemistry at both the start of pumping and after 10-20 years of operation. Density-dependent solute-transport modeling is thus an integral component of the design of brackish groundwater RO systems. The accuracy of groundwater models is dependent upon the quality of the hydrogeological data upon which they are based. Key elements of the aquifer characterization are the determination of the three-dimensional distribution of salinity within the aquifer and the evaluation of aquifer heterogeneity with respect to hydraulic conductivity. It is necessary to know from where in a pumped aquifer (or aquifer zone) water is being produced and the contribution of vertical flow to the produced water. Unexpected, excessive vertical migration (up-coning) of waters that are more saline has adversely impacted some RO systems because the salinity of the water delivered to the system exceeded the system design parameters. Improved aquifer characterization is possible using advanced geophysical techniques, which can, in turn, lead to more accurate solute-transport models. Advanced borehole geophysical logs, such as nuclear magnetic resonance, were run as part of the exploratory test

The origin of brackish and saline groundwater in the coastal area of the Netherlands

NARCIS (Netherlands)

Post, VEA; Van der Plicht, H; Meijer, HAJ

An explanation is presented for the origin of brackish to saline groundwater in the coastal area of the Netherlands based on geological, chemical (chlorinity), isotopic and geophysical data. A critical review of all possible salinization mechanisms shows that the origin of the brackish water is

The effect of ice-cream-scoop water on the hygiene of ice cream.

Science.gov (United States)

Wilson, I. G.; Heaney, J. C.; Weatherup, S. T.

1997-01-01

A survey of unopened ice cream, ice cream in use, and ice-cream-scoop water (n = 91) was conducted to determine the effect of scoop water hygiene on the microbiological quality of ice cream. An aerobic plate count around 10(6) c.f.u. ml-1 was the modal value for scoop waters. Unopened ice creams generally had counts around 10(3)-10(4) c.f.u. ml-1 and this increased by one order of magnitude when in use. Many scoop waters had low coliform counts, but almost half contained > 100 c.f.u. ml-1. E. coli was isolated in 18% of ice creams in use, and in 10% of unopened ice creams. S. aureus was not detected in any sample. Statistical analysis showed strong associations between indicator organisms and increased counts in ice cream in use. EC guidelines for indicator organisms in ice cream were exceeded by up to 56% of samples. PMID:9287941

Comparative studies on plasma mineral status of cattle in fluoride toxic brackish water zone of Punjab, India

Directory of Open Access Journals (Sweden)

Sushma Chhabra

2012-05-01

Full Text Available Objective: Chronic fluoride intoxication or fluorosis is a worldwide health problem in humans and animals. The present research work was aimed to assess the status of copper, zinc, cobalt, manganese, magnesium, calcium and phosphorus in blood of fluorotic cattle in brackish water zone of Punjab. Methods: The present study was conducted in villages of district Muktsar, a brackish water zone, of Punjab state. Cattle (n=103 showing signs of dental lesions or lameness, from the villages with water fluoride concentration more than 1 ppm, were selected for the study whereas cattle (n=98 from villages with water fluoride concentration less than 1 ppm and with no clinical signs served as control. Blood samples were collected from both the groups and were analysed for minerals.Results: Significantly (P<0.05 higher plasma F concentrations were observed in animals of fluorotic region in comparison to healthy control animals. Concentrations of plasma Ca, Mg, Cu and Zn were significantly lower in cattle of hydrofluorotic region. Plasma phosphorus, iron and iodine concentrations were higher in animals of hydrofluorotic region whereas Mo and Mn did not differ between the two groups. Conclusions: Present study indicated decrease in certain essential minerals in animals of fluorotic region and such changes may contribute to the toxic effects associated with exposure to excess fluoride and salinity

Influence of Chlorination and Choice of Materials on Fouling in Cooling Water System under Brackish Seawater Conditions

Directory of Open Access Journals (Sweden)

Pauliina Rajala

2016-06-01

Full Text Available Cooling systems remove heat from components and industrial equipment. Water cooling, employing natural waters, is typically used for cooling large industrial facilities, such as power plants, factories or refineries. Due to moderate temperatures, cooling water cycles are susceptible to biofouling, inorganic fouling and scaling, which may reduce heat transfer and enhance corrosion. Hypochlorite treatment or antifouling coatings are used to prevent biological fouling in these systems. In this research, we examine biofouling and materials’ degradation in a brackish seawater environment using a range of test materials, both uncoated and coated. The fouling and corrosion resistance of titanium alloy (Ti-6Al-4V, super austenitic stainless steel (254SMO and epoxy-coated carbon steel (Intershield Inerta160 were studied in the absence and presence of hypochlorite. Our results demonstrate that biological fouling is intensive in cooling systems using brackish seawater in sub-arctic areas. The microfouling comprised a vast diversity of bacteria, archaea, fungi, algae and protozoa. Chlorination was effective against biological fouling: up to a 10–1000-fold decrease in bacterial and archaeal numbers was detected. Chlorination also changed the diversity of the biofilm-forming community. Nevertheless, our results also suggest that chlorination enhances cracking of the epoxy coating.

Influence of Chlorination and Choice of Materials on Fouling in Cooling Water System under Brackish Seawater Conditions.

Science.gov (United States)

Rajala, Pauliina; Bomberg, Malin; Huttunen-Saarivirta, Elina; Priha, Outi; Tausa, Mikko; Carpén, Leena

2016-06-15

Cooling systems remove heat from components and industrial equipment. Water cooling, employing natural waters, is typically used for cooling large industrial facilities, such as power plants, factories or refineries. Due to moderate temperatures, cooling water cycles are susceptible to biofouling, inorganic fouling and scaling, which may reduce heat transfer and enhance corrosion. Hypochlorite treatment or antifouling coatings are used to prevent biological fouling in these systems. In this research, we examine biofouling and materials' degradation in a brackish seawater environment using a range of test materials, both uncoated and coated. The fouling and corrosion resistance of titanium alloy (Ti-6Al-4V), super austenitic stainless steel (254SMO) and epoxy-coated carbon steel (Intershield Inerta160) were studied in the absence and presence of hypochlorite. Our results demonstrate that biological fouling is intensive in cooling systems using brackish seawater in sub-arctic areas. The microfouling comprised a vast diversity of bacteria, archaea, fungi, algae and protozoa. Chlorination was effective against biological fouling: up to a 10-1000-fold decrease in bacterial and archaeal numbers was detected. Chlorination also changed the diversity of the biofilm-forming community. Nevertheless, our results also suggest that chlorination enhances cracking of the epoxy coating.

Sensitivity of open-water ice growth and ice concentration evolution in a coupled atmosphere-ocean-sea ice model

Science.gov (United States)

Shi, Xiaoxu; Lohmann, Gerrit

2017-09-01

A coupled atmosphere-ocean-sea ice model is applied to investigate to what degree the area-thickness distribution of new ice formed in open water affects the ice and ocean properties. Two sensitivity experiments are performed which modify the horizontal-to-vertical aspect ratio of open-water ice growth. The resulting changes in the Arctic sea-ice concentration strongly affect the surface albedo, the ocean heat release to the atmosphere, and the sea-ice production. The changes are further amplified through a positive feedback mechanism among the Arctic sea ice, the Atlantic Meridional Overturning Circulation (AMOC), and the surface air temperature in the Arctic, as the Fram Strait sea ice import influences the freshwater budget in the North Atlantic Ocean. Anomalies in sea-ice transport lead to changes in sea surface properties of the North Atlantic and the strength of AMOC. For the Southern Ocean, the most pronounced change is a warming along the Antarctic Circumpolar Current (ACC), owing to the interhemispheric bipolar seasaw linked to AMOC weakening. Another insight of this study lies on the improvement of our climate model. The ocean component FESOM is a newly developed ocean-sea ice model with an unstructured mesh and multi-resolution. We find that the subpolar sea-ice boundary in the Northern Hemisphere can be improved by tuning the process of open-water ice growth, which strongly influences the sea ice concentration in the marginal ice zone, the North Atlantic circulation, salinity and Arctic sea ice volume. Since the distribution of new ice on open water relies on many uncertain parameters and the knowledge of the detailed processes is currently too crude, it is a challenge to implement the processes realistically into models. Based on our sensitivity experiments, we conclude a pronounced uncertainty related to open-water sea ice growth which could significantly affect the climate system sensitivity.

Effects of plant diversity on primary production and species interactions in brackish water angiosperm communities

DEFF Research Database (Denmark)

Salo, Tiina; Gustafsson, Camilla; Boström, Christoffer

2009-01-01

Research on plant biodiversity and ecosystem functioning has mainly focused on terrestrial ecosystems, and our understanding of how plant species diversity and interactions affect processes in marine ecosystems is still limited. To investigate if plant species richness and composition influence...... plant productivity in brackish water angiosperm communities, a 14 wk field experiment was conducted. Using a replacement design with a standardized initial aboveground biomass, shoots of Zostera marina, Potamogeton filiformis and P. perfoliatus were planted on a shallow, sandy bottom in replicated...

MATHEMATICAL MODEL OF ICE FORMATION ON TEPLOOBMENNOGO SIDE OF THETHERMOELECTRIC DESALINATION PLANT

Directory of Open Access Journals (Sweden)

A. M. Gajiyev

2016-01-01

Full Text Available Abstract. The necessity of the use of technology and analytically summarizes the methods of desalination of seawater and brackish waters. Tasked to investigate the processes occurring in the desalination plant with the continuous process of freezing of ice on heat transfer surface with a film mode of fluid motion.To solve this problem the article deals with mathematical cal model of ice formation on heat transfer surfaces and thermo-electric distiller. The model allows us to estimate the rise time and the thickness of the ice under specified conditions of temperature and flow of water. It is shown that the use of thermoelectric converters allows the flexibility to adjust the mode of ice formation. Solved the problem of determining the maximum thickness of the ice at which freezing is possible film of water flowing through it at a predetermined temperature of the cooling plate and the cooling capacity of the thermoelectric battery.It is established that the performance of thermoelectric opreznitive of the system increases due to the increase in the number of cooled surfaces, and the use of the heat from the hot junction of the converters for melting of ice increases the energy efficiency of the system as a whole. 

Sputtering of water ice

DEFF Research Database (Denmark)

Baragiola, R.A.; Vidal, R.A.; Svendsen, W.

2003-01-01

We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from...

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in Na-Cl brackish waters of north-western Sardinia, Italy

Science.gov (United States)

Mongelli, G.; Monni, S.; Oggiano, G.; Paternoster, M.; Sinisi, R.

2013-01-01

In the Mediterranean area the demand of good quality water is often threatened by salinization, especially in coastal areas. The salinization is the result of concomitant processes due to both marine water intrusion and rock-water interaction, which in some cases are hardly distinguishable. In northwestern Sardinia, in the Nurra area, salinization due to marine water intrusion has been recently evidenced as consequence of bore hole exploitation. However, the geology of the Nurra records a long history from Paleozoic to Quaternary, resulting in relative structural complexity and in a wide variety of lithologies, including Triassic evaporites. To elucidate the origin of the saline component in the Nurra aquifer, may furnish a useful and more general model for the salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activities and recent climatic changes, the Nurra has become vulnerable to desertification and, similarly to other Mediterranean islands, surface-water resources can periodically suffer from drastic shortage. With this in mind we report new data, regarding brackish waters of Na-Cl type of the Nurra, including major ions and selected trace elements (B, Br, I and Sr) and isotopic data, including δ18O, δD in water, and δ34S and δ18O in dissolved sulphate. To better depict the origin of the salinity we also analyzed a set of Nurra Triassic evaporites for mineralogical and isotopic composition. The brackish waters have Cl contents up to 2025 mg L-1 and the ratios between dissolved ions and chlorine, with the exception of the Br/Cl ratio, are not those expected on the basis of a simple mixing between rain water and seawater. The δ18O and δD data indicate that most of the waters are within the Regional Meteoric Water Line and the Global Meteoric Water Line supporting the idea that they are meteoric in origin. A relevant consequence of the

Gaining the necessary geologic, hydrologic, and geochemical understanding for additional brackish groundwater development, coastal San Diego, California, USA

Science.gov (United States)

Danskin, Wesley R.

2012-01-01

Local water agencies and the United States Geological Survey are using a combination of techniques to better understand the scant freshwater resources and the much more abundant brackish resources in coastal San Diego, California, USA. Techniques include installation of multiple-depth monitoring well sites; geologic and paleontological analysis of drill cuttings; geophysical logging to identify formations and possible seawater intrusion; sampling of pore-water obtained from cores; analysis of chemical constituents including trace elements and isotopes; and use of scoping models including a three-dimensional geologic framework model, rainfall-runoff model, regional groundwater flow model, and coastal density-dependent groundwater flow model. Results show that most fresh groundwater was recharged during the last glacial period and that the coastal aquifer has had recurring intrusions of fresh and saline water. These intrusions disguise the source, flowpaths, and history of ground water near the coast. The flow system includes a freshwater lens resting on brackish water; a 100-meter-thick flowtube of freshwater discharging under brackish estuarine water and above highly saline water; and broad areas of fine-grained coastal sediment filled with fairly uniform brackish water. Stable isotopes of hydrogen and oxygen indicate the recharged water flows through many kilometers of fractured crystalline rock before entering the narrow coastal aquifer.

An integrated fish-plankton aquaculture system in brackish water.

Science.gov (United States)

Gilles, S; Fargier, L; Lazzaro, X; Baras, E; De Wilde, N; Drakidès, C; Amiel, C; Rispal, B; Blancheton, J-P

2013-02-01

Integrated Multi-Trophic Aquaculture takes advantage of the mutualism between some detritivorous fish and phytoplankton. The fish recycle nutrients by consuming live (and dead) algae and provide the inorganic carbon to fuel the growth of live algae. In the meanwhile, algae purify the water and generate the oxygen required by fishes. Such mechanism stabilizes the functioning of an artificially recycling ecosystem, as exemplified by combining the euryhaline tilapia Sarotherodon melanotheron heudelotii and the unicellular alga Chlorella sp. Feed addition in this ecosystem results in faster fish growth but also in an increase in phytoplankton biomass, which must be limited. In the prototype described here, the algal population control is exerted by herbivorous zooplankton growing in a separate pond connected in parallel to the fish-algae ecosystem. The zooplankton production is then consumed by tilapia, particularly by the fry and juveniles, when water is returned to the main circuit. Chlorella sp. and Brachionus plicatilis are two planktonic species that have spontaneously colonized the brackish water of the prototype, which was set-up in Senegal along the Atlantic Ocean shoreline. In our system, water was entirely recycled and only evaporation was compensated (1.5% volume/day). Sediment, which accumulated in the zooplankton pond, was the only trophic cul-de-sac. The system was temporarily destabilized following an accidental rotifer invasion in the main circuit. This caused Chlorella disappearance and replacement by opportunist algae, not consumed by Brachionus. Following the entire consumption of the Brachionus population by tilapias, Chlorella predominated again. Our artificial ecosystem combining S. m. heudelotii, Chlorella and B. plicatilis thus appeared to be resilient. This farming system was operated over one year with a fish productivity of 1.85 kg/m2 per year during the cold season (January to April).

Removal of fouling species from brackish water reverse osmosis reject stream.

Science.gov (United States)

Ayoub, G M; Korban, L; Al-Hindi, M; Zayyat, R

2018-03-01

Brine disposal from reverse osmosis (RO) systems remains a major challenge for the desalination industry especially in inland areas where discharge options are very limited. Solutions will entail the introduction of economic treatment processes that will alleviate the brine's negative impact on the environment and reduce its discharge volume. Such processes could act as an intermediary treatment process for the recycling of the brine through an additional RO stage which, for brackish water (BW) desalination, could lead to saving valuable water while reducing the amount of brine discharge. In this context, the study at hand attempts to evaluate the effectiveness of a one-step chemical process for the treatment of BWRO brine. This study seeks to determine optimal operating conditions relative to type, ratio, and dosage of alkalizing chemicals, pH and temperature, for substantially reducing the concentrations of scaling parameters such as calcium, magnesium, silica, and strontium. The results indicate that precipitation softening at pH = 11.5 using combined chemical dosages of NaOH and Na 2 CO 3 in a ratio of 2:1 leads to substantial removal of calcium and magnesium (>95%) and moderately high removal of strontium and silica (>71%).

Uptake and effects of americium-241 on a brackish-water amphipod

Energy Technology Data Exchange (ETDEWEB)

Hoppenheit, M.; Murray, C.N.; Woodhead, D.S.

1980-01-01

The present paper reports the results of experimental work undertaken using the brackish-water amphipod Gammarus duebeni duebeni and the transuranium nuclide americium-241. Data on the accumulation of this actinide showed that the larger fraction of the total body burden is associated with the exoskeleton. It was found that the body burden remained constant in the range pH 8.0-6.5 even though the water concentration changed markedly. It would thus appear that the concept of a concentration factor should be re-examined and it is proposed that a factor should be defined in terms of environmental and chemical parameters which represent the bioavailable fraction of the actinide. The effect of americium on survival and moulting was studied at two activity concentrations; the dose rates and absorbed doses under the experimental conditions employed have been estimated. The differences in survival rates between the control and irradiated groups were statistically analyzed and the significant difference at the higher concentration is believed to be due to a synergism between physiological stress and radiotoxicity of americium rather than the chemical toxicity of the element.

Uptake and effects of americium-241 on a brackish-water amphipod

International Nuclear Information System (INIS)

Hoppenheit, M.; Murray, C.N.; Woodhead, D.S.

1980-01-01

The present paper reports the results of experimental work undertaken using the brackish-water amphipod Gammarus duebeni duebeni and the transuranium nuclide americium-241. Data on the accumulation of this actinide showed that the larger fraction of the total body burden is associated with the exoskeleton. It was found that the body burden remained constant in the range pH 8.0-6.5 even though the water concentration changed markedly. It would thus appear that the concept of a concentration factor should be re-examined and it is proposed that a factor should be defined in terms of environmental and chemical parameters which represent the bioavailable fraction of the actinide. The effect of americium on survival and moulting was studied at two activity concentrations; the dose rates and absorbed doses under the experimental conditions employed have been estimated. The differences in survival rates between the control and irradiated groups were statistically analyzed and the significant difference at the higher concentration is believed to be due to a synergism between physiological stress and radiotoxicity of americium rather than the chemical toxicity of the element. (orig.) [de

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in the Na-Cl brackish waters of northwestern Sardinia, Italy

Science.gov (United States)

Mongelli, G.; Monni, S.; Oggiano, G.; Paternoster, M.; Sinisi, R.

2013-07-01

Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water-rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples) of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr), in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L-1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the conclusion that they are

Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in the Na-Cl brackish waters of northwestern Sardinia, Italy

Directory of Open Access Journals (Sweden)

G. Mongelli

2013-07-01

Full Text Available Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water–rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr, in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L−1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the

Environmental effects of thermal and radioactive discharges from nuclear power plants in the boreal brackish-water conditions of the northern Baltic Sea

International Nuclear Information System (INIS)

Ilus, E.

2009-08-01

During recent decades, thermal and radioactive discharges from nuclear power plants into the aquatic environment have become the subject of lively debate as an ecological concern. Recently, an increasing demand for facts has appeared in context with the Environmental Impact Assessment procedures that are being in progress for planned new nuclear power units in Finland. The target of this thesis was to summarize the large quantity of results obtained in extensive monitoring programmes and studies carried out in recipient sea areas off the Finnish nuclear power plants at Loviisa and Olkiluoto during more than four decades. Especially in the conditions specific for the northern Baltic Sea, where biota is poor and adapted to relatively low temperatures and to seasonal variation with a cold ice winter and a temperate summer, an increase in temperature may cause increased environmental stress to the organisms. Furthermore, owing to the brackish-water character of the Baltic Sea, many organisms live there near the limit of their physiological tolerance. On the other hand, the low salinity increases the uptake of certain radionuclides by many organisms in comparison with oceanic conditions. The sea areas surrounding the Finnish nuclear power plants differ from each other in many respects (efficiency of water exchange, levels of nutrients and other water quality parameters, water salinity and consequent differences in species composition, abundance and vitality of biota). In addition, there are differences in the discharge quantities and discharge design of the power plants. In this thesis the environmental effects of the two power plants on the water recipients are compared and their relative significance is assessed

Estratégias de uso de água salobra na produção de alface em hidroponia NFT Strategies for use of brackish water in NFT hydroponic lettuce production

Directory of Open Access Journals (Sweden)

Márcio S. Alves

2011-05-01

Full Text Available Plantas de alface crespa 'Verônica' foram cultivadas em condições hidropônicas, objetivando avaliar três diferentes estratégias de emprego de águas salobras: 1 águas salobras para reposição das perdas por evapotranspiração (ETc e água doce para o preparo da solução nutritiva (SN; 2 águas salobras para o preparo da SN e água doce para reposição da ETc; 3 águas salobras para o preparo da SN e reposição da ETc. Os níveis de salinidade da água foram obtidos pela adição de NaCl à água doce (0,27 dS m-1: 1,45; 2,51; 3,6; 5,41 e 7,5 dS m-1. O experimento foi conduzido em quatro blocos aleatorizados, com quatro repetições por tratamento. Uma estrutura de pesquisa foi construída com 72 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT. O uso de água salobra apenas para repor a ETc não produziu efeito sobre a produção da alface. Por outro lado, o uso de águas salobras para o preparo da SN e água doce para reposição da ETc, reduziu o rendimento da alface (massa de matéria fresca da parte aérea em 4,99% por (dS m-1. O rendimento foi reduzido em 7% por dS m-1 quando águas salobras foram usadas tanto para o preparo da SN quanto para reposição da ETc. Apesar da redução linear da produção da alface com o aumento da salinidade da água, sintomas depreciativos para a qualidade da alface hidropônica não foram registrados.Plants of crisphead lettuce cv. 'Verônica' were grown under hydroponic conditions aiming to evaluate three different strategies of brackish waters utilization: 1 brackish waters to replace the evapotranspiration loss (ETc and fresh water to prepare nutrient solution (NS; 2 brackish waters to prepare NS and fresh water to replace the ETc; 3 brackish waters to prepare NS and replace ETc. The levels of water salinity were obtained by addition of NaCl to fresh water (0.27 dS m-1: 1.45; 2.51; 3.6; 5.41 and 7.5 dS m-1. The experiment was conducted in randomized blocks with four

Autonomous system without batteries for brackish water desalination; Sistema autonomo sem baterias para dessalinizacao de agua salobra

Energy Technology Data Exchange (ETDEWEB)

Andrade, Eduardo Henrique Pereira de; Bezerra, Luiz Daniel Santos; Antunes, Fernando Luiz Marcelo [Universidade Federal do Ceara (PPGEE/UFC), Fortaleza, CE (Brazil). Programa de Pos -Graduacao em Engenharia Eletrica

2008-07-01

Ones of the goods most precious of the humanity, in the current times, with certainty is the drinking waters. Each scarcer and basic time for survival. In everybody more than 6,000 children die every day victims of some type of illness provoked for contaminated water (WHO, 2003). The underground water for being free of contamination is a good alternative, however its exploration if it becomes each more expensive time, since the water of better quality, is located in deeper sheets. In the state of the Ceara, techniques to explore water of deep well are each more frequent time, however, present a great inconvenience, most of the excavated wells, present brackish water, improper for the human consumption. In the attempt to make possible these wells the water is treated by desalination process. This article presents the practical implementation of a desalination the reverse Osmosis, Pump high-pressure supplied by solar photovoltaic energy system. (author)

Assimilation of ice and water observations from SAR imagery to improve estimates of sea ice concentration

Directory of Open Access Journals (Sweden)

K. Andrea Scott

2015-09-01

Full Text Available In this paper, the assimilation of binary observations calculated from synthetic aperture radar (SAR images of sea ice is investigated. Ice and water observations are obtained from a set of SAR images by thresholding ice and water probabilities calculated using a supervised maximum likelihood estimator (MLE. These ice and water observations are then assimilated in combination with ice concentration from passive microwave imagery for the purpose of estimating sea ice concentration. Due to the fact that the observations are binary, consisting of zeros and ones, while the state vector is a continuous variable (ice concentration, the forward model used to map the state vector to the observation space requires special consideration. Both linear and non-linear forward models were investigated. In both cases, the assimilation of SAR data was able to produce ice concentration analyses in closer agreement with image analysis charts than when assimilating passive microwave data only. When both passive microwave and SAR data are assimilated, the bias between the ice concentration analyses and the ice concentration from ice charts is 19.78%, as compared to 26.72% when only passive microwave data are assimilated. The method presented here for the assimilation of SAR data could be applied to other binary observations, such as ice/water information from visual/infrared sensors.

An investigation of desalination by nanofiltration, reverse osmosis and integrated (hybrid NF/RO) membranes employed in brackish water treatment.

Science.gov (United States)

Talaeipour, M; Nouri, J; Hassani, A H; Mahvi, A H

2017-01-01

As an appropriate tool, membrane process is used for desalination of brackish water, in the production of drinking water. The present study aims to investigate desalination processes of brackish water of Qom Province in Iran. This study was carried out at the central laboratory of Water and Wastewater Company of the studied area. To this aim, membrane processes, including nanofiltration (NF) and reverse osmosis (RO), separately and also their hybrid process were applied. Moreover, water physical and chemical parameters, including salinity, total dissolved solids (TDS), electric conductivity (EC), Na +1 and Cl -1 were also measured. Afterward, the rejection percent of each parameter was investigated and compared using nanofiltration and reverse osmosis separately and also by their hybrid process. The treatment process was performed by Luna domestic desalination device, which its membrane was replaced by two NF90 and TW30 membranes for nanofiltration and reverse osmosis processes, respectively. All collected brackish water samples were fed through membranes NF90-2540, TW30-1821-100(RO) and Hybrid (NF/RO) which were installed on desalination household scale pilot (Luna water 100GPD). Then, to study the effects of pressure on permeable quality of membranes, the simulation software model ROSA was applied. Results showed that percent of the salinity rejection was recorded as 50.21%; 72.82 and 78.56% in NF, RO and hybrid processes, respectively. During the study, in order to simulate the performance of nanofiltartion, reverse osmosis and hybrid by pressure drive, reverse osmosis system analysis (ROSA) model was applied. The experiments were conducted at performance three methods of desalination to remove physic-chemical parameters as percentage of rejections in the pilot plant are: in the NF system the salinity 50.21, TDS 43.41, EC 43.62, Cl 21.1, Na 36.15, and in the RO membrane the salinity 72.02, TDS 60.26, EC 60.33, Cl 43.08, Na 54.41. Also in case of the rejection in

Instability of water-ice interface under turbulent flow

Science.gov (United States)

Izumi, Norihiro; Naito, Kensuke; Yokokawa, Miwa

2015-04-01

It is known that plane water-ice interface becomes unstable to evolve into a train of waves. The underside of ice formed on the water surface of rivers are often observed to be covered with ice ripples. Relatively steep channels which discharge melting water from glaciers are characterized by beds covered with a series of steps. Though the flowing agent inducing instability is not water but gas including water vapor, a similar train of steps have been recently observed on the Polar Ice Caps on Mars (Spiral Troughs). They are expected to be caused by the instability of water-ice interface induced by flowing fluid on ice. There have been some studies on this instability in terms of linear stability analysis. Recently, Caporeale and Ridolfi (2012) have proposed a complete linear stability analysis in the case of laminar flow, and found that plane water-ice interface is unstable in the range of sufficiently large Reynolds numbers, and that the important parameters are the Reynolds number, the slope angle, and the water surface temperature. However, the flow inducing instability on water-ice interface in the field should be in the turbulent regime. Extension of the analysis to the case of fully developed turbulent flow with larger Reynolds numbers is needed. We have performed a linear stability analysis on the instability of water-ice interface under turbulent flow conditions with the use of the Reynolds-averaged Navier-Stokes equations with the mixing length turbulent model, the continuity equation of flow, the diffusion/dispersion equation of heat, and the Stefan equation. In order to reproduce the accurate velocity distribution and the heat transfer in the vicinity of smooth walls with the use of the mixing length model, it is important to take into account of the rapid decrease in the mixing length in the viscous sublayer. We employ the Driest model (1956) to the formulation. In addition, as the thermal boundary condition at the water surface, we describe the

Water ice and sub-micron ice particles on Tethys and Mimas

Science.gov (United States)

Scipioni, Francesca; Nordheim, Tom; Clark, Roger Nelson; D'Aversa, Emiliano; Cruikshank, Dale P.; Tosi, Federico; Schenk, Paul M.; Combe, Jean-Philippe; Dalle Ore, Cristina M.

2017-10-01

IntroductionWe present our ongoing work, mapping the variation of the main water ice absorption bands, and the distribution of the sub-micron particles, across Mimas and Tethys’ surfaces using Cassini-VIMS cubes acquired in the IR range (0.8-5.1 μm). We present our results in the form of maps of variation of selected spectral indicators (depth of absorption bands, reflectance peak height, spectral slopes).Data analysisVIMS acquires hyperspectral data in the 0.3-5.1 μm spectral range. We selected VIMS cubes of Tethys and Mimas in the IR range (0.8-5.1 μm). For all pixels in the selected cubes, we measured the band depths for water-ice absorptions at 1.25, 1.5 and 2.02 μm and the height of the 3.6 μm reflection peak. Moreover, we considered the spectral indictors for particles smaller than 1 µm [1]: (i) the 2 µm absorption band is asymmetric and (ii) it has the minimum shifted to longer λ (iii) the band depth ratio 1.5/2.0 µm decreases; (iv) the reflection peak at 2.6 µm decreases; (v) the Fresnel reflection peak is suppressed; (vi) the 5 µm reflectance is decreased relative to the 3.6 µm peak. To characterize the global variation of water-ice band depths, and of sub-micron particles spectral indicators, across Mimas and Tethys, we sampled the two satellites’ surfacees with a 1°x1° fixed-resolution grid and then averaged the band depths and peak values inside each square cell.3. ResultsFor both moons we find that large geologic features, such as the Odysseus and Herschel impact basins, do not correlate with water ice’s abundance variation. For Tethys, we found a quite uniform surface on both hemispheres. The only deviation from this pattern shows up on the trailing hemisphere, where we notice two north-oriented, dark areas around 225° and 315°. For Mimas, the leading and trailing hemispheres appear to be quite similar in water ice abundance, the trailing portion having water ice absorption bands lightly more suppressed than the leading side

Tunisian brackish water desalination by Electrodialysis : Opposing scaling and process optimization

International Nuclear Information System (INIS)

Elleuch, M.; Ben Amor, M.; Sistat, Ph.; Pourcelly, G.

2009-01-01

Electrodialysis (ED) did not know a mattering development in the desalination field because of problems usually related to energy consumption, the scaling and/or precipitation phenomenon of certain mineral salts (CaSO 4 , CaCO 3 , etc.). and the importance of investments which they require. So, to mitigate some of these problems and to increase the electrodialysis processes potentialities, we introduced a crystallisation inhibitor (sodium polyacrylate RPI2000) into the concentration compartment during Ed's operations. Then we studied some parameters such as the applied potential or the circulation flow of studied solutions. The inhibitor addition allowed to delay the precipitation in the ED concentration comportment, confining so the brine in a small volume and decrease the frequency of replacement of membranes, which will reduce the cost of the process. Without adding scaling inhibitors, a set of experiment was performed using synthetic water supersaturated on CaCO 3 and CaSO 4 at room temperature. Several flows rates are tested (80, 60, 40 and 30 L/h). We applied 20 V until the conductivity measured in the dilute compartment dropped approximately from 9000 =μS/cm to 1500 μS/cm. We used the same concentrate solution to treat many synthetic water volumes. The results showed us that more the flow is important more the phenomenon of scaling is delayed. In order to increase the performance of the electrodialysis process we applied a pulsed electric field with different duty cycle (Ton = Toff = 1, 3, 10 and 30 seconds). Then, we compare conductivity evolution in the dilute as a function of the pulse mode. The results shows a faster decrease of the concentration in the dilute under pulsed field conditions. Pulsed electric field electrodialysis seems to be very promising for future development in brackish water desalination, to some extent it can remove some well known limitations of electrodialysis. Experiments on desalination of brackish water by pulse field

The Influence of CO2 Enrichment on Net Photosynthesis of Seagrass Zostera marina in a Brackish Water Environment

OpenAIRE

Pajusalu, Liina; Martin, Georg; Põllumäe, Arno; Paalme, Tiina

2016-01-01

Seagrasses are distributed across the globe and their communities may play key roles in the coastal ecosystems. Seagrass meadows are expected to benefit from the increased carbon availability which might be used in photosynthesis in a future high CO2 world. The main aim of this study was to examine the effect of elevated pCO2 on the net photosynthesis of seagrass Zostera marina in a brackish water environment. The short-term mesocosm experiments were conducted in Kõiguste Bay (northern part o...

A simple and rapid in situ preconcentration method for the determination of phosphate in environmental waters by use of solid-phase extraction, and its applications to brackish lake waters.

Science.gov (United States)

Okumura, M; Tong, L; Fujinaga, K; Seike, Y

2001-05-01

A simple and rapid in situ preconcentration method for the determination of phosphate in environmental waters has been developed for field analysis. This method is based on solid-phase extraction on a zirconium-loaded Sep-Pack Accell CM cartridge (Zr-SP) and is applicable to studies in which sampling is performed by use of a graduated syringe to prevent contamination and to ensure easy operation at sampling sites. The Zr-SP cartridge was prepared by passing 0.1 mol L(-1) zirconium solution through a Sep-Pak Accell CM cartridge, packed with cation exchange sorbent based on a silica matrix. The adsorption of phosphate and its desorption depend only on the pH of the solution. A water sample containing phosphate was adjusted to pH 2 and passed through the Zr-SP cartridge to collect it. The retained phosphate was quantitatively eluted with 0.5 mol L(-1) sodium hydroxide solution. The phosphate retained in the Zr-SP cartridge was stable for at least one month. The established preconcentration method was successfully applied to brackish lake waters to investigate seasonal changes in the distribution and behavior of phosphate in a brackish lake.

Chlorine-containing salts as water ice nucleating particles on Mars

Science.gov (United States)

Santiago-Materese, D. L.; Iraci, L. T.; Clapham, M. E.; Chuang, P. Y.

2018-03-01

Water ice cloud formation on Mars largely is expected to occur on the most efficient ice nucleating particle available. Salts have been observed on the Martian surface and have been known to facilitate water cloud formation on Earth. We examined heterogeneous ice nucleation onto sodium chloride and sodium perchlorate substrates under Martian atmospheric conditions, in the range of 150 to 180 K and 10-7 to 10-5 Torr water partial pressure. Sub-155 K data for the critical saturation ratio (Scrit) suggests an exponential model best describes the temperature-dependence of nucleation onset of water ice for all substrates tested. While sodium chloride does not facilitate water ice nucleation more easily than bare silicon, sodium perchlorate does support depositional nucleation at lower saturation levels than other substrates shown and is comparable to smectite-rich clay in its ability to support cloud initiation. Perchlorates could nucleate water ice at partial pressures up to 40% lower than other substrates examined to date under Martian atmospheric conditions. These findings suggest air masses on Mars containing uplifted salts such as perchlorates could form water ice clouds at lower saturation ratios than in air masses absent similar particles.

WATER ICE IN THE KUIPER BELT

International Nuclear Information System (INIS)

Brown, M. E.; Fraser, W. C.; Schaller, E. L.

2012-01-01

We examine a large collection of low-resolution near-infrared spectra of Kuiper Belt objects (KBOs) and centaurs in an attempt to understand the presence of water ice in the Kuiper Belt. We find that water ice on the surface of these objects occurs in three separate manners: (1) Haumea family members uniquely show surfaces of nearly pure water ice, presumably a consequence of the fragmentation of the icy mantle of a larger differentiated proto-Haumea; (2) large objects with absolute magnitudes of H < 3 (and a limited number to H = 4.5) have surface coverings of water ice—perhaps mixed with ammonia—that appears to be related to possibly ancient cryovolcanism on these large objects; and (3) smaller KBOs and centaurs which are neither Haumea family members nor cold-classical KBOs appear to divide into two families (which we refer to as 'neutral' and 'red'), each of which is a mixture of a common nearly neutral component and either a slightly red or very red component that also includes water ice. A model suggesting that the difference between neutral and red objects due to formation in an early compact solar system either inside or outside, respectively, of the ∼20 AU methanol evaporation line is supported by the observation that methanol is only detected on the reddest objects, which are those which would be expected to have the most of the methanol containing mixture.

Combinação de águas doce e salobra para produção de alface hidropônica Combination of fresh and brackish waters for hydroponic lettuce production

Directory of Open Access Journals (Sweden)

Tales M. Soares

2010-07-01

Full Text Available Plantas de alface crespa cv. Verônica foram cultivadas em condição hidropônica objetivando-se avaliar dois tipos de emprego combinado de águas doce e salobras, quais sejam: usar as águas salobras para preparar a solução nutritiva (SN e a água doce para repor a evapotranspiração da cultura (ETc (Experimento I e usar a água doce para preparar a SN e as salobras para a reposição da ETc (Experimento II. Uma estrutura de pesquisa com 40 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT foi construída. Os níveis de salinidade da água testados foram: 0,585; 1,17; 1,755; 2,925 e 4,095 g L-1 de NaCl. A salinidade diminuiu a produtividade da alface (massa de matéria fresca da parte aérea em 10,9 e 3,91% para cada acréscimo unitário na salinidade da água (g L-1 de NaCl, considerando-se os Experimentos I e II, respectivamente. De acordo com os resultados obtidos com os dois tipos de combinação de águas doce e salobras, o uso de águas salobras para repor a ETc pode aumentar a produtividade da alface em comparação com o uso dessas águas para preparar a SN.Plants of crisphead lettuce cv. Verônica were grown under hydroponic conditions aiming to evaluate two types of combination of brackish and fresh waters: using the brackish waters to prepare nutrient solution (NS and fresh water to replace the evapotranspiration loss (ETc (Experiment I and using the fresh water to prepare NS and the brackish waters to replace the ETc loss (Experiment II. A research structure was built up with 40 experimental units which simulated the nutrient film technique (NFT. The levels of water salinity were 0.585; 1.17; 1.755; 2.925 and 4.095 g L-1 NaCl. The lettuce yield (fresh shoot matter decreased 10.9 and 3.91% for each unit increase in water salinity (g L-1 NaCl in Experiments I and II, respectively. According to results obtained with the two types of combination of fresh and brackish waters, the use of brackish waters to replace

Water, ice and mud: Lahars and lahar hazards at ice- and snow-clad volcanoes

Science.gov (United States)

Waythomas, Christopher F.

2014-01-01

Large-volume lahars are significant hazards at ice and snow covered volcanoes. Hot eruptive products produced during explosive eruptions can generate a substantial volume of melt water that quickly evolves into highly mobile flows of ice, sediment and water. At present it is difficult to predict the size of lahars that can form at ice and snow covered volcanoes due to their complex flow character and behaviour. However, advances in experiments and numerical approaches are producing new conceptual models and new methods for hazard assessment. Eruption triggered lahars that are ice-dominated leave behind thin, almost unrecognizable sedimentary deposits, making them likely to be under-represented in the geological record.

Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

Science.gov (United States)

Hudait, Arpa; Molinero, Valeria

2014-06-04

Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

Proceedings of the 19. IAHR international symposium on ice : using new technology to understand water-ice interaction

International Nuclear Information System (INIS)

Jasek, M.; Andrishak, R.; Siddiqui, A.

2008-01-01

This conference provided a venue for scientists, engineers and researchers an opportunity to expand their knowledge of water-ice interactions with reference to water resources, river and coastal hydraulics, risk analysis, energy and the environment. The the theme of new technology falls into 3 basic groups, notably measurement and instrumentation; remote sensing; and numerical simulation. The thermal regime of rivers was discussed along with ice mechanics, ice hydraulics, ice structures and modelling ice phenomena. The titles of the sessions were: river ice, glaciers and climate change; freeze-up processes on rivers and oceans; river ice-structure interactions; numerical simulations in ice engineering; river-ice break-up and ice jam formation; ice measurement; Grasse River ice evaluation; evaluation of structural ice control alternatives; remote sensing; hydropower and dam decommissioning; mechanical behaviour of river ice, ice covered flow and thermal modelling; mathematical and computer model formulations for ice friction and sea ice; ice bergs and ice navigation; ice crushing processes; sea ice and shore/structure interactions; ice properties, testing and physical modelling; ice actions on compliant structures; oil spills in ice; desalination, ice thickness and climate change; and, sea ice ridges. The conference featured 123 presentations, of which 20 have been catalogued separately for inclusion in this database. refs., tabs., figs

Water ice grains in comet C/2013 US10 (Catalina)

Science.gov (United States)

Protopapa, Silvia; Kelley, Michael S. P.; Yang, Bin; Woodward, Charles E.; Sunshine, Jessica M.

2017-10-01

Knowledge of the the physical properties of water ice in cometary nuclei is critical in determining how the Solar System was formed. While it is difficult to directly study the properties of water ice in comet nuclei, we can study comet interiors through their comae. Cometary activity makes the interiors of these objects available for characterization. However, the properties (grain size, abundance, purity, chemical state) of water-ice grains detected in the coma do not necessarily represent the characteristics of the water ice on the surface and/or in the interior of the nucleus. This is due to the potential physical and chemical evolution of the emitted material. Once in the coma, water-ice grains are heated by sunlight, and if temperatures are warm enough, they sublime. In this case, their sizes and potentially their ice-to-dust fractions are reduced.We present IRTF/SpeX measurements of the Oort cloud comet C/2013 US10 (Catalina), which reached perihelion in Nov 2015 at a heliocentric distance Rh=0.822 AU. Observations of US10 were acquired on UT 2014-08-13, 2016-01-12, and 2016-08-13 (Rh=5.9, 1.3, and 3.9 AU). This set of measurements, spanning a broad range in Rh, are rare and fundamental for estimating how ice grains evolve in the coma. The spectrum obtained close to perihelion is featureless and red sloped, which is consistent with a dust-dominated coma. Conversely, the spectra acquired on August 2014 and 2016 display neutral slopes and absorption bands at 1.5 and 2.0 μm, consistent with the presence of water-ice grains. These variations in water ice with heliocentric distance are correlated with sublimation rates. Additionally, the measurements obtained at 5.8 AU and 3.9 AU are nearly identical, suggesting that water-ice grains, once in the coma, do not sublime significantly. Therefore, the properties of these long-lived water-ice grains may represent their state in the nucleus or immediately after insertion into the coma. We will present radiative

Dynamics of ice nucleation on water repellent surfaces.

Science.gov (United States)

Alizadeh, Azar; Yamada, Masako; Li, Ri; Shang, Wen; Otta, Shourya; Zhong, Sheng; Ge, Liehui; Dhinojwala, Ali; Conway, Ken R; Bahadur, Vaibhav; Vinciquerra, A Joseph; Stephens, Brian; Blohm, Margaret L

2012-02-14

Prevention of ice accretion and adhesion on surfaces is relevant to many applications, leading to improved operation safety, increased energy efficiency, and cost reduction. Development of passive nonicing coatings is highly desirable, since current antiicing strategies are energy and cost intensive. Superhydrophobicity has been proposed as a lead passive nonicing strategy, yet the exact mechanism of delayed icing on these surfaces is not clearly understood. In this work, we present an in-depth analysis of ice formation dynamics upon water droplet impact on surfaces with different wettabilities. We experimentally demonstrate that ice nucleation under low-humidity conditions can be delayed through control of surface chemistry and texture. Combining infrared (IR) thermometry and high-speed photography, we observe that the reduction of water-surface contact area on superhydrophobic surfaces plays a dual role in delaying nucleation: first by reducing heat transfer and second by reducing the probability of heterogeneous nucleation at the water-substrate interface. This work also includes an analysis (based on classical nucleation theory) to estimate various homogeneous and heterogeneous nucleation rates in icing situations. The key finding is that ice nucleation delay on superhydrophobic surfaces is more prominent at moderate degrees of supercooling, while closer to the homogeneous nucleation temperature, bulk and air-water interface nucleation effects become equally important. The study presented here offers a comprehensive perspective on the efficacy of textured surfaces for nonicing applications.

Proton dynamics and the phase diagram of dense water ice.

Science.gov (United States)

Hernandez, J-A; Caracas, R

2018-06-07

All the different phases of water ice between 2 GPa and several megabars are based on a single body-centered cubic sub-lattice of oxygen atoms. They differ only by the behavior of the hydrogen atoms. In this study, we investigate the dynamics of the H atoms at high pressures and temperatures in water ice from first-principles molecular dynamics simulations. We provide a detailed analysis of the O-H⋯O bonding dynamics over the entire stability domain of the body-centered cubic (bcc) water ices and compute transport properties and vibrational density-of-states. We report the first ab initio evidence for a plastic phase of water and we propose a coherent phase diagram for bcc water ices compatible with the two groups of melting curves and with the multiple anomalies reported in ice VII around 15 GPa.

Martian North Polar Water-Ice Clouds During the Viking Era

Science.gov (United States)

Tamppari, L. K.; Bass, D. S.

2000-01-01

The Viking Orbiters determined that the surface of Mars' northern residual cap consists of water ice. Observed atmospheric water vapor abundances in the equatorial regions have been related to seasonal exchange between reservoirs such as the polar caps, the regolith and between different phases in the atmosphere. Kahn modeled the physical characteristics of ice hazes seen in Viking Orbiter imaging limb data, hypothesizing that ice hazes provide a method for scavenging water vapor from the atmosphere and accumulating it into ice particles. Given that Jakosky found that these particles had sizes such that fallout times were of order one Martian sol, these water-ice hazes provided a method for returning more water to the regolith than that provided by adsorption alone. These hazes could also explain the rapid hemispheric decrease in atmospheric water in late northern summer as well as the increase during the following early spring. A similar comparison of water vapor abundance versus polar cap brightness has been done for the north polar region. They have shown that water vapor decreases steadily between L(sub s) = 100-150 deg while polar cap albedo increases during the same time frame. As a result, they suggested that late summer water-ice deposition onto the ice cap may be the cause of the cap brightening. This deposition could be due to adsorption directly onto the cap surface or to snowfall. Thus, an examination of north polar waterice clouds could lend insight into the fate of the water vapor during this time period. Additional information is contained in the original extended abstract.

River ice implications related to water power production in Norway

Energy Technology Data Exchange (ETDEWEB)

Asvall, R.P. [Norwegian Water Resources and Energy Directorate, Oslo (Norway). Hydrology Dept.

2009-07-01

Nearly 99 per cent of the electricity produced in Norway is based on water power. While the period of large power development is over, the current focus lies in developing small hydroelectric power plants. A new market based energy law was implemented in Norway in 1991 to achieve more efficient use of electricity production by means of market forces. Since water regulation influences ice conditions in lakes and rivers, this paper focused on the implications of changes in ice conditions. In Norway, the expected changes in ice conditions are taken into account when issuing permits for water regulations and schemes for water discharge because some waterways are used as winter roads. Follow-up includes both close and long term observations and measurements. The impact of variable price on power was also discussed, with particular reference to ice conditions in cases where water discharge occurs on rivers. This paper summarized selected ice problems and how they have been handled. The paper also included a summary of anticipated climatic changes relevant to ice conditions.

River ice implications related to water power production in Norway

International Nuclear Information System (INIS)

Asvall, R.P.

2009-01-01

Nearly 99 per cent of the electricity produced in Norway is based on water power. While the period of large power development is over, the current focus lies in developing small hydroelectric power plants. A new market based energy law was implemented in Norway in 1991 to achieve more efficient use of electricity production by means of market forces. Since water regulation influences ice conditions in lakes and rivers, this paper focused on the implications of changes in ice conditions. In Norway, the expected changes in ice conditions are taken into account when issuing permits for water regulations and schemes for water discharge because some waterways are used as winter roads. Follow-up includes both close and long term observations and measurements. The impact of variable price on power was also discussed, with particular reference to ice conditions in cases where water discharge occurs on rivers. This paper summarized selected ice problems and how they have been handled. The paper also included a summary of anticipated climatic changes relevant to ice conditions.

The role of water ice clouds in the Martian hydrologic cycle

Science.gov (United States)

James, Philip B.

1990-01-01

A one-dimensional model for the seasonal cycle of water on Mars has been used to investigate the direction of the net annual transport of water on the planet and to study the possible role of water ice clouds, which are included as an independent phase in addition to ground ice and water vapor, in the cycle. The calculated seasonal and spatial patterns of occurrence of water ice clouds are qualitatively similar to the observed polar hoods, suggesting that these polar clouds are, in fact, an important component of water cycle. A residual dry ice in the south acts as a cold trap which, in the absence of sources other than the caps, will ultimately attract the water ice from the north cap; however, in the presence of a source of water in northern midlatitudes during spring, it is possible that the observed distribution of vapor and ice can be in a steady state even if a residual CO2 cap is a permanent feature of the system.

Evaluating the piscicide rotenone as an option for eradication of invasive Mozambique tilapia in a Hawaiian brackish-water wetland complex

Science.gov (United States)

Nico, Leo; Englund, Ronald A.; Jelks, Howard L.

2015-01-01

Mozambique tilapia Oreochromis mossambicus were recently discovered in ‘Aimakapā Fishpond, a 12-hectare brackish-water wetland complex in Kaloko-Honokōhau National Historical Park, on the Island of Hawai’i. As a possible eradication method, we evaluated rotenone, a natural piscicide used in fish management and the active ingredient in plants traditionally used by indigenous Hawaiians for capturing fish. To assess rotenone’s efficacy in killing tilapia and effects on non-target species, laboratory toxicity tests involved exposing organisms to various concentrations of liquid CFT Legumine (5% rotenone) in static trials of 48-h to 72-h duration. Test organisms included: Mozambique tilapia, non-native guppy Poecilia reticulata, the non-native odonate Rambur’s forktail Ischnura ramburii, native feeble shrimp Palaemon debilis, and native ‘ōpae’ula shrimp Halocaridina rubra. All organisms and water used in tests were obtained from ‘Aimakapā (12.6–12.7 ppt salinity), or, for H. rubra, an anchialine pool (15.0–15.2 ppt salinity). Survival analyses indicated CFT Legumine concentrations >3 ppm (>0.15 mg/L rotenone) achieved 100% mortality of tilapia and 93% of guppies within 24 h, with most tilapia killed by 6 h and most guppies by 2 h. Little or no mortality was observed among invertebrate exposed to 1 to 5 mg/L CFT Legumine: 0% mortality for ‘ōpae’ula shrimp, 4% for feeble shrimp; and 16% for odonate larvae. The 48 h LC50 values for Mozambique tilapia and guppy were 0.06 and 0.11 mg/L rotenone, respectively. Results demonstrate rotenone’s potential for non-native fish eradication in brackish-water habitats, with benefit of low mortality to certain macro-invertebrates. High rotenone tolerance displayed by ‘ōpae’ula shrimp is noteworthy. Invasive fish are common in anchialine pools, threatening existence of shrimp and other invertebrate fauna. Although rotenone’s effects on freshwater organisms have been well studied, our research

A Microbial Community in Sediments Beneath the Western Antarctic Ice Sheet, Ice Stream C (Kamb)

Science.gov (United States)

Skidmore, M.; Han, S.; Foo, W.; Bui, D.; Lanoil, B.

2004-12-01

In 2000, an ice-drilling project focusing on the "sticky spot" of Ice Stream C recovered cores of sub-glacial sediments from beneath the Western Antarctic Ice Sheet. We have characterized several chemical and microbiological parameters of the sole intact sediment core. Pore waters extracted from these sediments were brackish and some were supersaturated with respect to calcite. Ion chromatography demonstrated the presence of several organic acids at low, but detectable, levels in the pore water. DAPI direct cell counts were approximately 107 cells g-1. Aerobic viable plate counts were much lower than direct cell counts; however, they were two orders of magnitude higher on plates incubated at low temperature (4 ° C; 3.63 x 105 CFU ml-1) than at higher temperatures (ca. 22° C; 1.5 x 103 CFU ml-1); no colonies were detected on plates incubated anaerobically at either temperature. 16S rDNA clone library analysis indicates extremely limited bacterial diversity in these samples: six phylogenetic clades were detected. The three dominant bacterial phylogenetic clades in the clone libraries (252 clones total) were most closely related to Thiobacillus thioparus (180 clones), Polaromonas vacuolata (34 clones), and Gallionella ferruginea (35 clones) and their relatives; one clone each represented the other three phylogenetic clades (most closely related to Ralstonia pickettii, Lysobacter antibioticus, and Xylella fastidiosa, respectively). These sequences match closely with sequences previously obtained from other subglacial environments in Alaska, Ellesmere Island, Canada and New Zealand. Implications of this microbial community to subglacial chemistry and microbial biogeography will be discussed.

Nye Lecture: Water Under Ice: Curiosities, Complexities, and Catastrophes

Science.gov (United States)

Clarke, G. K.

2006-12-01

Meltwater beneath glaciers and ice sheets activates some of the most curious and impressive phenomena known to glaciology. These range from the generation of miniscule electrokinetic currents by water flow through subglacial sediment to massive outburst floods that rearrange landscapes and deliver freshwater pulses to the ocean. The source of this water varies but is some mix of surface water and water melted from the glacier base by geothermal and frictional heating. The outflow of subglacial water is somewhat affected by bed topography but the dominant influence is from gradients in ice overburden pressure and thus from the surface topography of the ice sheet. Upslope water flow is possible and large adverse bed slopes are required before topographic water traps can exist. As a consequence, subglacial topographic basins tend to be leaky and less than 5% of the area of the contemporary Antarctic Ice Sheet provides suitable habitat for subglacial lakes. Following a variety of subglacial pathways, water can migrate toward the ice margins, either as a liquid or as refrozen meltwater accreted to the ice base. The morphology of the subglacial water system is thought to comprise a combination of sheet-like, channel-like, and vein-like elements, all of which lend themselves to mathematical representation. Water transport processes need not operate in a steady fashion and morphological switching between sheet-like and channel-like endmembers is linked to spectacular events such as glacier surges and outburst floods. Large outbursts of proglacially or subglacially-stored meltwater, the classic Icelandic j{ö}kulhaups, continue to occur in glaciated regions of the world and much larger floods were released during the Late Pleistocene--Early Holocene deglaciation of the Northern Hemisphere. Whether large subglacial lakes like Lake Vostok, Earth's seventh largest lake, have similar potential for delivering cataclysmic floods remains uncertain. The recent detection of a small

Water/ice phase transition: The role of zirconium acetate, a compound with ice-shaping properties

Science.gov (United States)

Marcellini, Moreno; Fernandes, Francisco M.; Dedovets, Dmytro; Deville, Sylvain

2017-04-01

Few compounds feature ice-shaping properties. Zirconium acetate is one of the very few inorganic compounds reported so far to have ice-shaping properties similar to that of ice-shaping proteins, encountered in many organisms living at low temperature. When a zirconium acetate solution is frozen, oriented and perfectly hexagonal ice crystals can be formed and their growth follows the temperature gradient. To shed light on the water/ice phase transition while freezing zirconium acetate solution, we carried out differential scanning calorimetry measurements. From our results, we estimate how many water molecules do not freeze because of their interaction with Zr cations. We estimate the colligative properties of the Zr acetate on the apparent critical temperature. We further show that the phase transition is unaffected by the nature of the base which is used to adjust the pH. Our results provide thus new hints on the ice-shaping mechanism of zirconium acetate.

Could the Hokusai Impact Have Delivered Mercury's Water Ice?

Science.gov (United States)

Ernst, C. M.; Chabot, N. L.; Barnouin, O. S.

2018-05-01

Hokusai is the best candidate source crater for Mercury’s water-ice inventory if it was primarily delivered by a single impact event. The Hokusai impact could account for the inventory of water ice on Mercury for impact velocities <30 km/s.

When Big Ice Turns Into Water It Matters For Houses, Stores And Schools All Over

Science.gov (United States)

Bell, R. E.

2017-12-01

When ice in my glass turns to water it is not bad but when the big ice at the top and bottom of the world turns into water it is not good. This new water makes many houses, stores and schools wet. It is really bad during when the wind is strong and the rain is hard. New old ice water gets all over the place. We can not get to work or school or home. We go to the big ice at the top and bottom of the world to see if it will turn to water soon and make more houses wet. We fly over the big ice to see how it is doing. Most of the big ice sits on rock. Around the edge of the big sitting on rock ice, is really low ice that rides on top of the water. This really low ice slows down the big rock ice turning into water. If the really low ice cracks up and turns into little pieces of ice, the big rock ice will make more houses wet. We look to see if there is new water in the cracks. Water in the cracks is bad as it hurts the big rock ice. Water in the cracks on the really low ice will turn the low ice into many little pieces of ice. Then the big rock ice will turn to water. That is water in cracks is bad for the houses, schools and businesses. If water moves off the really low ice, it does not stay in the cracks. This is better for the really low ice. This is better for the big rock ice. We took pictures of the really low ice and saw water leaving. The water was not staying in the cracks. Water leaving the really low ice might be good for houses, schools and stores.

Viscosity of interfacial water regulates ice nucleation

International Nuclear Information System (INIS)

Li, Kaiyong; Chen, Jing; Zhang, Qiaolan; Zhang, Yifan; Xu, Shun; Zhou, Xin; Cui, Dapeng; Wang, Jianjun; Song, Yanlin

2014-01-01

Ice formation on solid surfaces is an important phenomenon in many fields, such as cloud formation and atmospheric icing, and a key factor for applications in preventing freezing. Here, we report temperature-dependent nucleation rates of ice for hydrophilic and hydrophobic surfaces. The results show that hydrophilic surface presents a lower ice nucleation rate. We develop a strategy to extract the thermodynamic parameters, J 0 and Γ, in the context of classical nucleation theory. From the extracted J 0 and Γ, we reveal the dominant role played by interfacial water. The results provide an insight into freezing mechanism on solid surfaces

Hexagonal ice in pure water and biological NMR samples

Energy Technology Data Exchange (ETDEWEB)

Bauer, Thomas; Gath, Julia; Hunkeler, Andreas; Ernst, Matthias, E-mail: maer@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland); Böckmann, Anja, E-mail: a.bockmann@ibcp.fr [UMR 5086 CNRS, Université de Lyon 1, Institut de Biologie et Chimie des Protéines (France); Meier, Beat H., E-mail: beme@ethz.ch [ETH Zurich, Physical Chemistry (Switzerland)

2017-01-15

Ice, in addition to “liquid” water and protein, is an important component of protein samples for NMR spectroscopy at subfreezing temperatures but it has rarely been observed spectroscopically in this context. We characterize its spectroscopic behavior in the temperature range from 100 to 273 K, and find that it behaves like pure water ice. The interference of magic-angle spinning (MAS) as well as rf multiple-pulse sequences with Bjerrum-defect motion greatly influences the ice spectra.

Brackish to hypersaline lake dolostones of the Mississippian

Science.gov (United States)

Bennett, Carys; Kearsey, Timothy; Davies, Sarah; Millward, David; Marshall, John

2016-04-01

, and 9% of all dolostone beds in the Norham Core are pedogenically altered. The isotopic composition of dolomite beds is δ18O -3.6‰ to -1.7‰ and δ13C -2.6‰ to 1.6‰ which is consistent with a brackish as opposed to marine origin. The dolostones are categorised by their sedimentary composition: Facies 1: Cemented siltstone and sandstone; Facies 2: Homogeneous micrite to micro-crystaline dolomite, within a clay matrix; Facies 3: Bedded dolomite and siltstone; Facies 4: Mixed calcite and dolomite; Facies 5: Dolomite with gypsum and anhydrite. Formation processes are diverse, and include diagenetic cementation (Facies 1), deposition in saline (brackish) lakes (Facies 2), deposition in saline lakes with clastic sediment input (Facies 3), lagoonal to shallow-marine carbonate deposition (Facies 4), and hypersaline lake to sabkha environments (Facies 5). 60% of the beds are facies 2 or 3 and their sedimentology, fauna, ichnofauna and isotopic composition indicate a brackish-water origin. Other Mississippian dolostones from around the world also contain a fairly restricted fauna and have been interpreted as brackish water deposits. The mechanism of dolomite formation under these conditions is discussed. These dolostones provided extensive coastal lakes that may have been an important habitat for tetrapods and other transitional groups during the Mississippian.

Early diagenetic high-magnesium calcite and dolomite indicate that coal balls formed in marine or brackish water: Stratigraphic and paleoclimatic implications

Science.gov (United States)

Raymond, Anne

2016-04-01

Coal balls are carbonate and pyrite permineralizations of peat that contain three-dimensional plant fossils preserved at the cellular level. Coal balls, which occur in Pennsylvanian and earliest Permian equatorial coals, provide a detailed record of terrestrial ecology and tropical climate during the Late Paleozoic Ice Age; yet their depositional environment remains controversial. The exquisite preservation of some coal-ball fossils, e.g. pollen with pollen tubes and leaves with mesophyll, indicates rapid formation. The presence of abundant, cement-filled, void spaces within and between the plant debris in most coal balls indicates that they formed in uncompacted peat, near the surface of the mire. Botanical, taphonomic and isotopic evidence point to a freshwater origin for coal balls. The nearest living relatives of coal ball plants (modern lycopsids, sphenopsids, marratialean ferns and conifers) grow in fresh water. Coal-ball peat contains a high percentage of aerial debris, similar to modern freshwater peat. The stable oxygen isotopes of coal-ball carbonate (δ18O = 16 to 3 per mil) suggest a freshwater origin. However, the widespread occurrence of marine invertebrates and early diagenetic framboidal pyrite in coal balls suggests that many formed in close proximity to marine water. Indeed, carbonate petrology points to a marine or brackish water origin for the first-formed carbonate cements in coal balls. Petrographic and geochemical (microprobe) analysis of coal-ball carbonates in Pennsylvanian coals from the midcontinent of North America (Western Interior Basin, West Pangaea) and the Ruhr and Donets Basins (East Pangaea) indicate that the first formed carbonate is either radaxial, nonstochiometric dolomite or high magnesium calcite (9 - 17 mol % MgCO3, indicating precipitation in marine or brackish water. Although both primary dolomite and high magnesium calcite can form in lacustrine settings, the lakes in which these minerals form occur in carbonate terranes

Efficacy of sanitized ice in reducing bacterial load on fish fillet and in the water collected from the melted ice.

Science.gov (United States)

Feliciano, Lizanel; Lee, Jaesung; Lopes, John A; Pascall, Melvin A

2010-05-01

This study investigated the efficacy of sanitized ice for the reduction of bacteria in the water collected from the ice that melted during storage of whole and filleted Tilapia fish. Also, bacterial reductions on the fish fillets were investigated. The sanitized ice was prepared by freezing solutions of PRO-SAN (an organic acid formulation) and neutral electrolyzed water (NEW). For the whole fish study, the survival of the natural microflora was determined from the water of the melted ice prepared with PRO-SAN and tap water. These water samples were collected during an 8 h storage period. For the fish fillet study, samples were inoculated with Escherichia coli K12, Listeria innocua, and Pseudomonas putida then stored on crushed sanitized ice. The efficacies of these were tested by enumerating each bacterial species on the fish fillet and in the water samples at 12 and 24 h intervals for 72 h, respectively. Results showed that each bacterial population was reduced during the test. However, a bacterial reduction of fillet samples. A maximum of approximately 2 log CFU and > 3 log CFU reductions were obtained in the waters sampled after the storage of whole fish and the fillets, respectively. These reductions were significantly (P < 0.05) higher in the water from sanitized ice when compared with the water from the unsanitized melted ice. These results showed that the organic acid formulation and NEW considerably reduced the bacterial numbers in the melted ice and thus reduced the potential for cross-contamination.

Redescription of Chironomus salinarius (Diptera: Chironomidae), nuisance midges that emerged in brackish water of Jinhae-man (Bay), Kyongsangnam-do, Korea

Science.gov (United States)

Yum, Jin-Hwoa

2006-01-01

Huge numbers of non-biting midges emerged from brackish water which were made at the harbor construction field in Jinhae City, Kyongsangnam-do, Korea in late summer in 2005, and caused a serious nuisance to villagers. The midges were collected and identified as Chironomus salinarius (Kieffer, 1921). Although this species was recorded in Korea for the first time in 1998, the morphological descriptions were so brief and simple. A full redescription is made with detailed illustrations for ecological and control workers of this nuisance midge. PMID:16514284

Caltech water-ice dusty plasma: preliminary results

Science.gov (United States)

Bellan, Paul; Chai, Kilbyoung

2013-10-01

A water-ice dusty plasma laboratory experiment has begun operation at Caltech. As in Ref., a 1-5 watt parallel-plate 13.56 MHz rf discharge plasma has LN2-cooled electrodes that cool the neutral background gas to cryogenic temperatures. However, instead of creating water vapor by in-situ deuterium-oxygen bonding, here the neutral gas is argon and water vapor is added in a controlled fashion. Ice grains spontaneously form after a few seconds. Photography with a HeNe line filter of a sheet of HeNe laser light sheet illuminating a cross section of dust grains shows a large scale whorl pattern composed of concentric sub-whorls having wave-like spatially varying intensity. Each sub-whorl is composed of very evenly separated fine-scale stream-lines indicating that the ice grains move in self-organized lanes like automobiles on a multi-line highway. HeNe laser extinction together with an estimate of dust density from the intergrain spacing in photographs indicates a 5 micron nominal dust grain radius. HeNe laser diffraction patterns indicate the ice dust grains are large and ellipsoidal at low pressure (200 mT) but small and spheroidal at high pressure (>600 mT). Supported by USDOE.

Hydrogeology of northern Sierra de Chiapas, Mexico: a conceptual model based on a geochemical characterization of sulfide-rich karst brackish springs

Science.gov (United States)

Rosales Lagarde, Laura; Boston, Penelope J.; Campbell, Andrew R.; Hose, Louise D.; Axen, Gary; Stafford, Kevin W.

2014-09-01

Conspicuous sulfide-rich karst springs flow from Cretaceous carbonates in northern Sierra de Chiapas, Mexico. This is a geologically complex, tropical karst area. The physical, geologic, hydrologic and chemical attributes of these springs were determined and integrated into a conceptual hydrogeologic model. A meteoric source and a recharge elevation below 1,500 m are estimated from the spring-water isotopic signature regardless of their chemical composition. Brackish spring water flows at a maximum depth of 2,000 m, as inferred from similar chemical attributes to the produced water from a nearby oil well. Oil reservoirs may be found at depths below 2,000 m. Three subsurface environments or aquifers are identified based on the B, Li+, K+ and SiO2 concentrations, spring water temperatures, and CO2 pressures. There is mixing between these aquifers. The aquifer designated Local is shallow and contains potable water vulnerable to pollution. The aquifer named Northern receives some brackish produced water. The composition of the Southern aquifer is influenced by halite dissolution enhanced at fault detachment surfaces. Epigenic speleogenesis is associated with the Local springs. In contrast, hypogenic speleogenesis is associated with the brackish sulfidic springs from the Northern and the Southern environments.

Isolation, identification, screening of toxicity and oligopeptides of some marine and brackish cyanobacteria from Norwegian and Pakistani waters, in the search for bioactive natural compounds

OpenAIRE

Hameed, Shaista

2009-01-01

Cyanobacteria produce a number of bioactive compounds, most of them are oligopeptides. Almost all are known from freshwater species. The aim of this study was to search for marine and brackish water species producing bioactive compounds. To reach this goal, new strains were isolated from Norwegian and Pakistani coastal waters. These and additional strains from NIVA, UiO and UiB culture collections (24 in total), belonging to Chroococcales and Oscillatoriales, were identified based on morpholo...

WATER ICE AT THE SURFACE OF THE HD 100546 DISK

International Nuclear Information System (INIS)

Honda, M.; Kudo, T.; Terada, H.; Takato, N.; Takatsuki, S.; Nakamoto, T.; Inoue, A. K.; Fukagawa, M.; Tamura, M.

2016-01-01

We made near-infrared multicolor imaging observations of a disk around Herbig Be star HD 100546 using Gemini/NICI. K (2.2 μm), H 2 O ice (3.06 μm), and L′ (3.8 μm) disk images were obtained and we found a 3.1 μm absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on Oka et al., including the water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by both the disk models with and without the photodesorption effect within the measurement accuracy, but the model with photodesorption effects is slightly more favored, implying that the UV photons play an important role in the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement to the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models

WATER ICE AT THE SURFACE OF THE HD 100546 DISK

Energy Technology Data Exchange (ETDEWEB)

Honda, M. [Department of Physics, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011 (Japan); Kudo, T.; Terada, H.; Takato, N. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, Hawaii 96720 (United States); Takatsuki, S.; Nakamoto, T. [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Inoue, A. K. [College of General Education, Osaka Sangyo University, Daito, Osaka 574-8530 (Japan); Fukagawa, M.; Tamura, M. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2016-04-10

We made near-infrared multicolor imaging observations of a disk around Herbig Be star HD 100546 using Gemini/NICI. K (2.2 μm), H{sub 2}O ice (3.06 μm), and L′ (3.8 μm) disk images were obtained and we found a 3.1 μm absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on Oka et al., including the water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by both the disk models with and without the photodesorption effect within the measurement accuracy, but the model with photodesorption effects is slightly more favored, implying that the UV photons play an important role in the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement to the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models.

A scheme for parameterizing ice cloud water content in general circulation models

Science.gov (United States)

Heymsfield, Andrew J.; Donner, Leo J.

1989-01-01

A method for specifying ice water content in GCMs is developed, based on theory and in-cloud measurements. A theoretical development of the conceptual precipitation model is given and the aircraft flights used to characterize the ice mass distribution in deep ice clouds is discussed. Ice water content values derived from the theoretical parameterization are compared with the measured values. The results demonstrate that a simple parameterization for atmospheric ice content can account for ice contents observed in several synoptic contexts.

Heterogeneous Ice Nucleation: Interplay of Surface Properties and Their Impact on Water Orientations.

Science.gov (United States)

Glatz, Brittany; Sarupria, Sapna

2018-01-23

Ice is ubiquitous in nature, and heterogeneous ice nucleation is the most common pathway of ice formation. How surface properties affect the propensity to observe ice nucleation on that surface remains an open question. We present results of molecular dynamics studies of heterogeneous ice nucleation on model surfaces. The models surfaces considered emulate the chemistry of kaolinite, an abundant component of mineral dust. We investigate the interplay of surface lattice and hydrogen bonding properties in affecting ice nucleation. We find that lattice matching and hydrogen bonding are necessary but not sufficient conditions for observing ice nucleation at these surfaces. We correlate this behavior to the orientations sampled by the metastable supercooled water in contact with the surfaces. We find that ice is observed in cases where water molecules not only sample orientations favorable for bilayer formation but also do not sample unfavorable orientations. This distribution depends on both surface-water and water-water interactions and can change with subtle modifications to the surface properties. Our results provide insights into the diverse behavior of ice nucleation observed at different surfaces and highlight the complexity in elucidating heterogeneous ice nucleation.

Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze-thaw cycles.

Science.gov (United States)

Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry

2016-02-01

Freeze-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during freeze-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze-thaw cycles in tree stems. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

The impact of radiatively active water-ice clouds on Martian mesoscale atmospheric circulations

Science.gov (United States)

Spiga, A.; Madeleine, J.-B.; Hinson, D.; Navarro, T.; Forget, F.

2014-04-01

Background and Goals Water ice clouds are a key component of the Martian climate [1]. Understanding the properties of the Martian water ice clouds is crucial to constrain the Red Planet's climate and hydrological cycle both in the present and in the past [2]. In recent years, this statement have become all the more true as it was shown that the radiative effects of water ice clouds is far from being as negligible as hitherto believed; water ice clouds plays instead a key role in the large-scale thermal structure and dynamics of the Martian atmosphere [3, 4, 5]. Nevertheless, the radiative effect of water ice clouds at lower scales than the large synoptic scale (the so-called meso-scales) is still left to be explored. Here we use for the first time mesoscale modeling with radiatively active water ice clouds to address this open question.

Investigation of heterogeneous ice nucleation in pollen suspensions and washing water

Science.gov (United States)

Dreischmeier, Katharina; Budke, Carsten; Koop, Thomas

2014-05-01

Biological particles such as pollen often show ice nucleation activity at temperatures higher than -20 °C. Immersion freezing experiments of pollen washing water demonstrate comparable ice nucleation behaviour as water containing the whole pollen bodies (Pummer et al., 2012). It was suggested that polysaccharide molecules leached from the grains are responsible for the ice nucleation. Here, heterogeneous ice nucleation in birch pollen suspensions and their washing water was investigated by two different experimental methods. The optical freezing array BINARY (Bielefeld Ice Nucleation ARraY) allows the direct observation of freezing of microliter-sized droplets. The IN spectra obtained from such experiments with birch pollen suspensions over a large concentration range indicate several different ice nucleation active species, two of which are present also in the washing water. The latter was probed also in differential scanning calorimeter (DSC) experiments of emulsified sub-picoliter droplets. Due to the small droplet size in the emulsion samples and at small concentration of IN in the washing water, such DSC experiments can exhibit the ice nucleation behaviour of a single nucleus. The two heterogeneous freezing signals observed in the DSC thermograms can be assigned to two different kinds of ice nuclei, confirming the observation from the BINARY measurements, and also previous studies on Swedish birch pollen washing water (Augustin et al., 2012). The authors gratefully acknowledge funding by the German Research Foundation (DFG) through the project BIOCLOUDS (KO 2944/1-1) and through the research unit INUIT (FOR 1525) under KO 2944/2-1. We particularly thank our INUIT partners for fruitful collaboration and sharing of ideas and IN samples. S. Augustin, H. Wex, D. Niedermeier, B. Pummer, H. Grothe, S. Hartmann, L. Tomsche, T. Clauss, J. Voigtländer, K. Ignatius, and F. Stratmann, Immersion freezing of birch pollen washing water, Atmos. Chem. Phys., 13, 10989

Forced convective melting at an evolving ice-water interface

Science.gov (United States)

Ramudu, Eshwan; Hirsh, Benjamin; Olson, Peter; Gnanadesikan, Anand

2015-11-01

The intrusion of warm Circumpolar Deep Water into the ocean cavity between the base of ice shelves and the sea bed in Antarctica causes melting at the ice shelves' basal surface, producing a turbulent melt plume. We conduct a series of laboratory experiments to investigate how the presence of forced convection (turbulent mixing) changes the delivery of heat to the ice-water interface. We also develop a theoretical model for the heat balance of the system that can be used to predict the change in ice thickness with time. In cases of turbulent mixing, the heat balance includes a term for turbulent heat transfer that depends on the friction velocity and an empirical coefficient. We obtain a new value for this coefficient by comparing the modeled ice thickness against measurements from a set of nine experiments covering one order of magnitude of Reynolds numbers. Our results are consistent with the altimetry-inferred melting rate under Antarctic ice shelves and can be used in climate models to predict their disintegration. This work was supported by NSF grant EAR-110371.

Hatching success in brackish water of Perca fluviatilis eggs obtained from the western Baltic Sea

DEFF Research Database (Denmark)

Christensen, Emil Aputsiaq Flindt; Skovrind, Mikkel; Olsen, Morten Tange

2016-01-01

tolerance of the eggs in vivo, and the salinities at which some populations spawn in situ (7 vs. 9.6 ‰). In the present study, hatching success of perch was determined in vivo for a Danish, western Baltic, brackish water population at salinities of 4, 7, 10 and 12 ‰. Furthermore, in order to place...... the population genetically among other European perch populations, individual egg samples were sequenced for a 390 base pair fragment of the mtDNA Dloop region. Hatching occurred at all four salinities, with no statistical differences among treatments. Successful hatching at 12 ‰ is well above salinities of 7......‰, which has previously been the highest reported from in vivo studies. This discrepancy is likely to be a result of methodological differences (e.g. different temperature) or perhaps interspecific variability in egg hatching abilities among perch populations. The perch from the present study consisted...

The phase diagram of water at negative pressures: virtual ices.

Science.gov (United States)

Conde, M M; Vega, C; Tribello, G A; Slater, B

2009-07-21

The phase diagram of water at negative pressures as obtained from computer simulations for two models of water, TIP4P/2005 and TIP5P is presented. Several solid structures with lower densities than ice Ih, so-called virtual ices, were considered as possible candidates to occupy the negative pressure region of the phase diagram of water. In particular the empty hydrate structures sI, sII, and sH and another, recently proposed, low-density ice structure. The relative stabilities of these structures at 0 K was determined using empirical water potentials and density functional theory calculations. By performing free energy calculations and Gibbs-Duhem integration the phase diagram of TIP4P/2005 was determined at negative pressures. The empty hydrates sII and sH appear to be the stable solid phases of water at negative pressures. The phase boundary between ice Ih and sII clathrate occurs at moderate negative pressures, while at large negative pressures sH becomes the most stable phase. This behavior is in reasonable agreement with what is observed in density functional theory calculations.

Adaptive genomic divergence under high gene flow between freshwater and brackish-water ecotypes of prickly sculpin (Cottus asper) revealed by Pool-Seq.

Science.gov (United States)

Dennenmoser, Stefan; Vamosi, Steven M; Nolte, Arne W; Rogers, Sean M

2017-01-01

Understanding the genomic basis of adaptive divergence in the presence of gene flow remains a major challenge in evolutionary biology. In prickly sculpin (Cottus asper), an abundant euryhaline fish in northwestern North America, high genetic connectivity among brackish-water (estuarine) and freshwater (tributary) habitats of coastal rivers does not preclude the build-up of neutral genetic differentiation and emergence of different life history strategies. Because these two habitats present different osmotic niches, we predicted high genetic differentiation at known teleost candidate genes underlying salinity tolerance and osmoregulation. We applied whole-genome sequencing of pooled DNA samples (Pool-Seq) to explore adaptive divergence between two estuarine and two tributary habitats. Paired-end sequence reads were mapped against genomic contigs of European Cottus, and the gene content of candidate regions was explored based on comparisons with the threespine stickleback genome. Genes showing signals of repeated differentiation among brackish-water and freshwater habitats included functions such as ion transport and structural permeability in freshwater gills, which suggests that local adaptation to different osmotic niches might contribute to genomic divergence among habitats. Overall, the presence of both repeated and unique signatures of differentiation across many loci scattered throughout the genome is consistent with polygenic adaptation from standing genetic variation and locally variable selection pressures in the early stages of life history divergence. © 2016 John Wiley & Sons Ltd.

The Contribution of Water Ice Clouds to the Water Cycle in the North Polar Region of Mars: Preliminary Analysis

Science.gov (United States)

Bass, D. S.; Tamppari, L. K.

2000-01-01

While it has long been known that Mars' north residual polar cap and the Martian regolith are significant sources of atmospheric water vapor, the amount of water vapor observed in the northern spring season by the Viking Mars Atmospheric Water Detector instrument (MAWD) cannot be attributed to cap and regolith sources alone. Kahn suggested that ice hazes may be the mechanism by which additional water is supplied to the Martian atmosphere. Additionally, a significant decrease in atmospheric water vapor was observed in the late northern summer that could not be correlated with the return of the cold seasonal C02 ice. While the detection of water ice clouds on Mars indicate that water exists in Mars' atmosphere in several different phases, the extent to which water ice clouds play a role in moving water through the Martian atmosphere remains uncertain. Work by Bass et. al. suggested that the time dependence of water ice cap seasonal variability and the increase in atmospheric water vapor depended on the polar cap center reaching 200K, the night time saturation temperature. Additionally, they demonstrated that a decrease in atmospheric water vapor may be attributed to deposition of water ice onto the surface of the polar cap; temperatures were still too warm at this time in the summer for the deposition of carbon dioxide. However, whether water ice clouds contribute significantly to this variability is unknown. Additional information is contained in original extended abstract.

A simulation study of homogeneous ice nucleation in supercooled salty water

Science.gov (United States)

Soria, Guiomar D.; Espinosa, Jorge R.; Ramirez, Jorge; Valeriani, Chantal; Vega, Carlos; Sanz, Eduardo

2018-06-01

We use computer simulations to investigate the effect of salt on homogeneous ice nucleation. The melting point of the employed solution model was obtained both by direct coexistence simulations and by thermodynamic integration from previous calculations of the water chemical potential. Using a seeding approach, in which we simulate ice seeds embedded in a supercooled aqueous solution, we compute the nucleation rate as a function of temperature for a 1.85 NaCl mol per water kilogram solution at 1 bar. To improve the accuracy and reliability of our calculations, we combine seeding with the direct computation of the ice-solution interfacial free energy at coexistence using the Mold Integration method. We compare the results with previous simulation work on pure water to understand the effect caused by the solute. The model captures the experimental trend that the nucleation rate at a given supercooling decreases when adding salt. Despite the fact that the thermodynamic driving force for ice nucleation is higher for salty water for a given supercooling, the nucleation rate slows down with salt due to a significant increase of the ice-fluid interfacial free energy. The salty water model predicts an ice nucleation rate that is in good agreement with experimental measurements, bringing confidence in the predictive ability of the model. We expect that the combination of state-of-the-art simulation methods here employed to study ice nucleation from solution will be of much use in forthcoming numerical investigations of crystallization in mixtures.

The Distribution of Basal Water Beneath the Greenland Ice Sheet from Radio-Echo Sounding

Science.gov (United States)

Jordan, T.; Williams, C.; Schroeder, D. M.; Martos, Y. M.; Cooper, M.; Siegert, M. J.; Paden, J. D.; Huybrechts, P.; Bamber, J. L.

2017-12-01

There is widespread, but often indirect, evidence that a significant fraction of the Greenland Ice Sheet is thawed at the bed. This includes major outlet glaciers and around the NorthGRIP ice-core in the interior. However, the ice-sheet-wide distribution of basal water is poorly constrained by existing observations, and the spatial relationship between basal water and other ice-sheet and subglacial properties is therefore largely unexplored. In principle, airborne radio-echo sounding (RES) surveys provide the necessary information and spatial coverage to infer the presence of basal water at the ice-sheet scale. However, due to uncertainty and spatial variation in radar signal attenuation, the commonly used water diagnostic, bed-echo reflectivity, is highly ambiguous and prone to spatial bias. Here we introduce a new RES diagnostic for the presence of basal water which incorporates both sharp step-transitions and rapid fluctuations in bed-echo reflectivity. This has the advantage of being (near) independent of attenuation model, and enables a decade of recent Operation Ice Bride RES survey data to be combined in a single map for basal water. The ice-sheet-wide water predictions are compared with: bed topography and drainage network structure, existing knowledge of the thermal state and geothermal heat flux, and ice velocity. In addition to the fast flowing ice-sheet margins, we also demonstrate widespread water routing and storage in parts of the slow-flowing northern interior. Notably, this includes a quasi-linear `corridor' of basal water, extending from NorthGRIP to Petermann glacier, which spatially correlates with a region of locally high (magnetic-derived) geothermal heat flux. The predicted water distribution places a new constraint upon the basal thermal state of the Greenland Ice Sheet, and could be used as an input for ice-sheet model simulations.

Effetively trapping air or lqiud water for anti-icing applications

Science.gov (United States)

Wang, Jianjun

2014-03-01

Icing on solid surfaces leads to operational difficulties and high maintenance efforts for power networks, aircrafts, ships, ground transportation vehicles and house-hold refrigerators, to name but a few. In extreme cases, icing on surfaces causes disastrous events such as crash of aircrafts and collapse of power networks, which result in severe economic impact and large loss of life. This talk is focused on the fundamentals of the ice formation and adhesion of ice with solid substrates aiming for fighting against icing on solid surfaces. When the supercooling is low, it would be possible to remove supercooled liquid water from the solid surfaces before freezing occurs. To achieve this, we design and constructed surfaces that can trap the air at the subfreezing temperature thus condensed water microdroplets could be spontaneously removed after the coalescence. When the supercooling is high, icing on surfaces occurs spontaniously. In this case, we constructed coatings on which aqueous lubricating layer could be trapped, thus the ice adhesion on the coating is so low that the ice formed atop could be removed by a wind action or its own gravity.

VOLATILE TRANSPORT INSIDE SUPER-EARTHS BY ENTRAPMENT IN THE WATER-ICE MATRIX

Energy Technology Data Exchange (ETDEWEB)

Levi, A.; Podolak, M. [Department of Geophysics and Planetary Science, Tel Aviv University, Tel Aviv 69978 (Israel); Sasselov, D., E-mail: amitlevi.planetphys@gmail.com [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-05-20

Whether volatiles can be entrapped in a background matrix composing planetary envelopes and be dragged via convection to the surface is a key question in understanding atmospheric fluxes, cycles, and composition. In this paper, we consider super-Earths with an extensive water mantle (i.e., water planets), and the possibility of entrapment of methane in their extensive water-ice envelopes. We adopt the theory developed by van der Waals and Platteeuw for modeling solid solutions, often used for modeling clathrate hydrates, and modify it in order to estimate the thermodynamic stability field of a new phase called methane filled ice Ih. We find that in comparison to water ice VII the filled ice Ih structure may be stable not only at the high pressures but also at the high temperatures expected at the core-water mantle transition boundary of water planets.

Isolation and evaluation of oil-producing microalgae from subtropical coastal and brackish waters.

Directory of Open Access Journals (Sweden)

David K Y Lim

Full Text Available Microalgae have been widely reported as a promising source of biofuels, mainly based on their high areal productivity of biomass and lipids as triacylglycerides and the possibility for cultivation on non-arable land. The isolation and selection of suitable strains that are robust and display high growth and lipid accumulation rates is an important prerequisite for their successful cultivation as a bioenergy source, a process that can be compared to the initial selection and domestication of agricultural crops. We developed standard protocols for the isolation and cultivation for a range of marine and brackish microalgae. By comparing growth rates and lipid productivity, we assessed the potential of subtropical coastal and brackish microalgae for the production of biodiesel and other oil-based bioproducts. This study identified Nannochloropsis sp., Dunaniella salina and new isolates of Chlorella sp. and Tetraselmis sp. as suitable candidates for a multiple-product algae crop. We conclude that subtropical coastal microalgae display a variety of fatty acid profiles that offer a wide scope for several oil-based bioproducts, including biodiesel and omega-3 fatty acids. A biorefinery approach for microalgae would make economical production more feasible but challenges remain for efficient harvesting and extraction processes for some species.

Industry water use : innovations, changes and challenges

International Nuclear Information System (INIS)

Braun, B.

2004-01-01

This paper presents work conducted by Canadian Natural Resources Ltd. (CNRL) in developing the McMurray Formation as an alternate water source in the Cold Lake Beaver River (CLBR) basin. Industry relies on both fresh water and brackish water to produce oil from thermal oil sands projects. A long-term sustainable supply of water is critical to the development of such projects. Although historically water has been considered as a renewable resource, it is currently viewed in a wider context. Technical advancements have made it possible to use recycled water for thermal recovery. Many heavy thermal oil expansions use brackish water. Capital costs are higher but heating costs are lower because brackish water is already warm. The use of brackish water allows companies to survive within their licenses while increasing production. Other possibilities include the use of depleted reservoir sections to store water to increase the use of recycled water. It was noted that brackish water resources need to be mapped and understood in greater detail. The objective is to use brackish water at a cost equal to, or less than fresh water. tabs., figs

Polyamorphism in Water: Amorphous Ices and their Glassy States

Science.gov (United States)

Amann-Winkel, K.; Boehmer, R.; Fujara, F.; Gainaru, C.; Geil, B.; Loerting, T.

2015-12-01

Water is ubiquitous and of general importance for our environment. But it is also known as the most anomalous liquid. The fundamental origin of the numerous anomalies of water is still under debate. An understanding of these anomalous properties of water is closely linked to an understanding of the phase diagram of the metastable non-crystalline states of ice. The process of pressure induced amorphization of ice was first observed by Mishima et al. [1]. The authors pressurized hexagonal ice at 77 K up to a pressure of 1.6 GPa to form high density amorphous ice (HDA). So far three distinct structural states of amorphous water are known [2], they are called low- (LDA), high- (HDA) and very high density amorphous ice (VHDA). Since the discovery of multiple distinct amorphous states it is controversy discussed whether this phenomenon of polyamorphism at high pressures is connected to the occurrence of more than one supercooled liquid phase [3]. Alternatively, amorphous ices have been suggested to be of nanocrystalline nature, unrelated to liquids. Indeed inelastic X-ray scattering measurements indicate sharp crystal-like phonons in the amorphous ices [4]. In case of LDA the connection to the low-density liquid (LDL) was inferred from several experiments including the observation of a calorimetric glass-to-liquid transition at 136 K and ambient pressure [5]. Recently also the glass transition in HDA was observed at 116 K at ambient pressure [6] and at 140 K at elevated pressure of 1 GPa [7], using calorimetric measurements as well as dielectric spectroscopy. We discuss here the general importance of amorphous ices and their liquid counterparts and present calorimetric and dielectric measurements on LDA and HDA. The good agreement between dielectric and calorimetric results convey for a clearer picture of water's vitrification phenomenon. [1] O. Mishima, L. D. Calvert, and E. Whalley, Nature 314, 76, 1985 [2] D.T. Bowron, J. L. Finney, A. Hallbrucker, et al., J. Chem

Ice versus liquid water saturation in simulations of the indian summer monsoon

Science.gov (United States)

Glazer, Russell H.; Misra, Vasubandhu

2018-02-01

At the same temperature, below 0 °C, the saturation vapor pressure (SVP) over ice is slightly less than the SVP over liquid water. Numerical models use the Clausius-Clapeyron relation to calculate the SVP and relative humidity, but there is not a consistent method for the treatment of saturation above the freezing level where ice and mixed-phase clouds may be present. In the context of current challenges presented by cloud microphysics in climate models, we argue that a better understanding of the impact that this treatment has on saturation-related processes like cloud formation and precipitation, is needed. This study explores the importance of the SVP calculation through model simulations of the Indian summer monsoon (ISM) using the regional spectral model (RSM) at 15 km grid spacing. A combination of seasonal and multiyear simulations is conducted with two saturation parameterizations. In one, the SVP over liquid water is prescribed through the entire atmospheric column (woIce), and in another the SVP over ice is used above the freezing level (wIce). When SVP over ice is prescribed, a thermodynamic drying of the middle and upper troposphere above the freezing level occurs due to increased condensation. In the wIce runs, the model responds to the slight decrease in the saturation condition by increasing, relative to the SVP over liquid water only run, grid-scale condensation of water. Increased grid-scale mean seasonal precipitation is noted across the ISM region in the simulation with SVP over ice prescribed. Modification of the middle and upper troposphere moisture results in a decrease in mean seasonal mid-level cloud amount and an increase in high cloud amount when SVP over ice is prescribed. Multiyear simulations strongly corroborate the qualitative results found in the seasonal simulations regarding the impact of ice versus liquid water SVP on the ISM's mean precipitation and moisture field. The mean seasonal rainfall difference over All India between wIce

DISCOVERY OF CRYSTALLIZED WATER ICE IN A SILHOUETTE DISK IN THE M43 REGION

Energy Technology Data Exchange (ETDEWEB)

Terada, Hiroshi [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Tokunaga, Alan T., E-mail: terada@subaru.naoj.org [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu 96822 (United States)

2012-07-01

We present the 1.9-4.2 {mu}m spectra of the five bright (L {<=} 11.2) young stars associated with silhouette disks with a moderate to high inclination angle of 39 Degree-Sign -80 Degree-Sign in the M42 and M43 regions. The water ice absorption is seen toward d121-1925 and d216-0939, while the spectra of d182-316, d183-405, and d218-354 show no water ice feature around 3.1 {mu}m within the detection limits. By comparing the water ice features toward nearby stars, we find that the water ice absorption toward d121-1925 and d216-0939 most likely originates from the foreground material and the surrounding disk, respectively. The angle of the disk inclination is found to be mainly responsible for the difference of the optical depth of the water ice among the five young stars. Our results suggest that there is a critical inclination angle between 65 Degree-Sign and 75 Degree-Sign for the circumstellar disk where the water ice absorption becomes strong. The average density at the disk surface of d216-0939 was found to be 6.38 Multiplication-Sign 10{sup -18} g cm{sup -3}. The water ice absorption band in the d216-0939 disk is remarkable in that the maximum optical depth of the water ice band is at a longer wavelength than detected before. It indicates that the primary carrier of the feature is purely crystallized water ice at the surface of the d216-0939 disk with characteristic size of {approx}0.8 {mu}m, which suggests grain growth. This is the first direct detection of purely crystallized water ice in a silhouette disk.

A balanced water layer concept for subglacial hydrology in large-scale ice sheet models

Directory of Open Access Journals (Sweden)

S. Goeller

2013-07-01

Full Text Available There is currently no doubt about the existence of a widespread hydrological network under the Antarctic Ice Sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux–basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

A balanced water layer concept for subglacial hydrology in large scale ice sheet models

Science.gov (United States)

Goeller, S.; Thoma, M.; Grosfeld, K.; Miller, H.

2012-12-01

There is currently no doubt about the existence of a wide-spread hydrological network under the Antarctic ice sheet, which lubricates the ice base and thus leads to increased ice velocities. Consequently, ice models should incorporate basal hydrology to obtain meaningful results for future ice dynamics and their contribution to global sea level rise. Here, we introduce the balanced water layer concept, covering two prominent subglacial hydrological features for ice sheet modeling on a continental scale: the evolution of subglacial lakes and balance water fluxes. We couple it to the thermomechanical ice-flow model RIMBAY and apply it to a synthetic model domain inspired by the Gamburtsev Mountains, Antarctica. In our experiments we demonstrate the dynamic generation of subglacial lakes and their impact on the velocity field of the overlaying ice sheet, resulting in a negative ice mass balance. Furthermore, we introduce an elementary parametrization of the water flux-basal sliding coupling and reveal the predominance of the ice loss through the resulting ice streams against the stabilizing influence of less hydrologically active areas. We point out, that established balance flux schemes quantify these effects only partially as their ability to store subglacial water is lacking.

Wind effects on prey availability: How northward migrating waders use brackish and hypersaline lagoons in the sivash, Ukraine

Science.gov (United States)

Verkuil, Yvonne; Koolhaas, Anita; Van Der Winden, Jan

Large numbers of waders migrating northward in spring use the Sivash, a large system of shallow, brackish and hypersaline lagoons in the Black Sea and Azov Sea region (Ukraine). The bottoms of these lagoons are often uncovered by the wind. Hence, for waders the time and space available for feeding depend on wind conditions. In hypersaline lagoons the benthic and pelagic fauna was very poor, consisting mainly of chironomid larvae (0.19 g AFDM·m -2) and brine shrimps Artemia salina, respectively. Brine shrimp abundance was correlated with salinity, wind force, wind direction and water depth. Dunlin Calidris alpina and curlew sandpiper Calidris ferruginea were the only species feeding on brine shrimp. As brine shrimp densities are higher in deeper water, smaller waders such as broad-billed sandpipers Limicola falcinellus are too short-legged to reach exploitable densities of brine shrimp. In brackish lagoons the benthic and pelagic fauna was rich, consisting of polychaetes, bivalves, gastropods, chironomid larvae, isopods and amphipods (8.9 to 30.5 g AFDM·m -2), but there were no brine shrimps. Prey biomass increased with the distance from the coast, being highest on the site that was most frequently inundated. Dunlin, broad-billed sandpiper and grey plover Pluvialis squatarola were the most abundant birds in the brackish lagoon. Due to the effects of wind-tides only a small area was usually available as a feeding site. Gammarus insensibilis was the alternative prey resource in the water layer, and their density varied with wind direction in the same way as brine shrimp. Curlew sandpipers and dunlins in the hypersaline lagoons and broad-billed sandpipers in the brackish lagoons often changed feeding sites, probably following the variation in prey availability. Only because of the large size and variety of lagoons are waders in the Sivash always able to find good feeding sites.

Reactive transport impacts on recovered freshwater quality during multiple partially penetrating wells (MPPW-)ASR in a brackish heterogeneous aquifer

NARCIS (Netherlands)

Zuurbier, Koen G.; Hartog, Niels; Stuyfzand, Pieter J.

The use of multiple partially penetrating wells (MPPW) during aquifer storage and recovery (ASR) in brackish aquifers can significantly improve the recovery efficiency (RE) of unmixed injected water. The water quality changes by reactive transport processes in a field MPPW-ASR system and their

Positron Lifetimes in Pure and Doped Ice and in Water

DEFF Research Database (Denmark)

Eldrup, Morten Mostgaard; Mogensen, O.; Trumpy, Georg

1972-01-01

for the other components show a complex behavior. The spectra for mono- and polycrystalline light ice and for polycrystalline heavy ice are identical. For water long lifetime components attributed to ortho-Ps are 1.86 nsec, 27% for H2O and 2.01 nsec, 22% for D2O. Theoretical explanations are suggested. Fast......Positron lifetime spectra were measured in mono- and polycrystalline light ice, polycrystalline heavy ice, doped light ice, as well as in light and heavy water. All spectra were resolved into three components. At temperatures between −196° and −100°C the lifetimes and relative intensities...... of the spectra are found by heating above approximately −120°C. Measurements on a number of fast frozen aqueous solutions of acids, bases, and salts are reported, none of them showing as strong influence on the ortho-Ps lifetime as HF. ©1972 The American Institute of Physics...

Heterogeneous ice nucleation in aqueous solutions: the role of water activity.

Science.gov (United States)

Zobrist, B; Marcolli, C; Peter, T; Koop, T

2008-05-01

Heterogeneous ice nucleation experiments have been performed with four different ice nuclei (IN), namely nonadecanol, silica, silver iodide and Arizona test dust. All IN are either immersed in the droplets or located at the droplets surface. The IN were exposed to various aqueous solutions, which consist of (NH4)2SO4, H2SO4, MgCl2, NaCl, LiCl, Ca(NO3)2, K2CO3, CH3COONa, ethylene glycol, glycerol, malonic acid, PEG300 or a NaCl/malonic acid mixture. Freezing was studied using a differential scanning calorimeter and a cold finger cell. The results show that the heterogeneous ice freezing temperatures decrease with increasing solute concentration; however, the magnitude of this effect is solute dependent. In contrast, when the results are analyzed in terms of the solution water activity a very consistent behavior emerges: heterogeneous ice nucleation temperatures for all four IN converge each onto a single line, irrespective of the nature of the solute. We find that a constant offset with respect to the ice melting point curve, Deltaaw,het, can describe the observed freezing temperatures for each IN. Such a behavior is well-known for homogeneous ice nucleation from supercooled liquid droplets and has led to the development of water-activity-based ice nucleation theory. The large variety of investigated solutes together with different general types of ice nuclei studied (monolayers, ionic crystals, covalently bound network-forming compounds, and a mixture of chemically different crystallites) underlines the general applicability of water-activity-based ice nucleation theory also for heterogeneous ice nucleation in the immersion mode. Finally, the ice nucleation efficiencies of the various IN, as well as the atmospheric implication of the developed parametrization are discussed.

The taming of brackish seepage

NARCIS (Netherlands)

Smits, F.J.C.; Olsthoorn, T.; Smulders, L.; van Wielink, I.

2016-01-01

In the area that is managed by the waterboard Amstel, Gooi and Vecht, some deep polders are located. Most of them attract large amounts of brackish seepage. This seepage not only contains salt, but also nutriënts.
Without hydrological intervention, the waterquality in the area would suffer

Triple Isotope Water Measurements of Lake Untersee Ice using Off-Axis ICOS

Science.gov (United States)

Berman, E. S.; Huang, Y. W.; Andersen, D. T.; Gupta, M.; McKay, C. P.

2015-12-01

Lake Untersee (71.348°S, 13.458°E) is the largest surface freshwater lake in the interior of the Gruber Mountains of central Queen Maud Land in East Antarctica. The lake is permanently covered with ice, is partly bounded by glacier ice and has a mean annual air temperature of -10°C. In contrast to other Antarctic lakes the dominating physical process controlling ice-cover dynamics is low summer temperatures and high wind speeds resulting in sublimation rather than melting as the main mass-loss process. The ice-cover of the lake is composed of lake-water ice formed during freeze-up and rafted glacial ice derived from the Anuchin Glacier. The mix of these two fractions impacts the energy balance of the lake, which directly affects ice-cover thickness. Ice-cover is important if one is to understand the physical, chemical, and biological linkages within these unique, physically driven ecosystems. We have analyzed δ2H, δ18O, and δ17O from samples of lake and glacier ice collected at Lake Untersee in Dec 2014. Using these data we seek to answer two specific questions: Are we able to determine the origin and history of the lake ice, discriminating between rafted glacial ice and lake water? Can isotopic gradients in the surface ice indicate the ablation (sublimation) rate of the surface ice? The triple isotope water analyzer developed by Los Gatos Research (LGR 912-0032) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology and incorporates proprietary internal thermal control for high sensitivity and optimal instrument stability. This analyzer measures δ2H, δ18O, and δ17O from water, as well as the calculated d-excess and 17O-excess. The laboratory precision in high performance mode for both δ17O and δ18O is 0.03 ‰, and for δ2H is 0.2 ‰. Methodology and isotope data from Lake Untersee samples are presented. Figure: Ice samples were collected across Lake Untersee from both glacial and lake ice regions for this study.

Potabilization of brackish water by electrodialysis. Study of natural samples with a laboratory unit.; Potabilizacion de aguas salobres por electrodialisis. Estudio de muestras naturales con una unidad de laboratorio

Energy Technology Data Exchange (ETDEWEB)

Sainz Sastre, J A; Alonso-Lopez, J

1972-07-01

Potabilization of brackish waters from Ciguela (Toledo) and Riansares (Toledo) rivers, and from wells 1 and 2 at Torre Pacheco (Murcia), as well as of sea water diluted to 5,000 ppm has been studied in process conditions optimized from experiments with synthetic solutions. The study includes: removal of suspended and organic matter, determination of limit current density, power requirements, ion selectivity and daily maximum output of the unit. (Author) 8 refs.

Accretion growth of water-ice grains in astrophysically-relevant dusty plasma experiment

Science.gov (United States)

Chai, Kil-Byoung; Marshall, Ryan; Bellan, Paul

2016-10-01

The grain growth process in the Caltech water-ice dusty plasma experiment has been studied using a high-speed camera equipped with a long-distance microscope lens. It is found that (i) the ice grain number density decreases four-fold as the average grain length increases from 20 to 80 um, (ii) the ice grain length has a log-normal distribution rather than a power-law dependence, and (iii) no collisions between ice grains are apparent. The grains have a large negative charge so the agglomeration growth is prevented by their strong mutual repulsion. It is concluded that direct accretion of water molecules is in good agreement with the observed ice grain growth. The volumetric packing factor of the ice grains must be less than 0.25 in order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains; this conclusion is consistent with ice grain images showing a fractal character.

First Detection of Water Ice and Organics on an Asteroid: A Possible Link to the Origin of Earth's Water

Science.gov (United States)

Hargrove, Kelsey D.; Campins, H.; Pinilla-Alonso, N.; Howell, E. S.; Kelley, M. S.; Licandro, J.; Mothédiniz, T.; Fernández, Y.; Ziffer, J.

2010-05-01

We report the detection of water ice and organics on the surface of asteroid 24 Themis. Our rotationally-resolved infrared (2-4 µm) spectra of this asteroid indicate that the ice and organics are widespread on its surface. The spectral difference with other asteroids observed in the same manner, makes 24 Themis unique so far. Our identification of water ice and organic compounds on this asteroid agrees with independent results (Rivkin and Emery 2010). At first glance, the presence of any surface ice on 24 Themis, particularly over a significant fraction of its surface, is puzzling because of the instability for exposed water ice at Themis's heliocentric distance ( 3.2 AU). Nevertheless, there are several possible sources for this unstable ice and identifying them is likely to be diagnostic of other processes on primitive asteroids. The presence of water ice on 24 Themis supports the idea that ice sublimation drives the cometary activity in two small members of the Themis dynamical family, labeled "Main Belt comets” by Hsieh and Jewitt (2006). It also helps to address other relevant questions, such as, how abundant is water ice in the outer asteroid belt and where was the "snow” line when the solar system formed? The answers to these questions could transform current views of primitive asteroids, delivery of water and organic molecules to Earth, and models of Solar System formation. This research was published in the April 29, 2010 issue of the journal Nature. Hargrove and Campins are visiting astronomers at the Infrared Telescope Facility (IRTF), which is operated by the University of Hawaii under Cooperative Agreement no. NCC 5-538 with the National Aeronautics and Space Administration

Selective removal of arsenic and monovalent ions from brackish water reverse osmosis concentrate.

Science.gov (United States)

Xu, Pei; Capito, Marissa; Cath, Tzahi Y

2013-09-15

Concentrate disposal and management is a considerable challenge for the implementation of desalination technologies, especially for inland applications where concentrate disposal options are limited. This study has focused on selective removal of arsenic and monovalent ions from brackish groundwater reverse osmosis (RO) concentrate for beneficial use and safe environmental disposal using in situ and pre-formed hydrous ferric oxides/hydroxides adsorption, and electrodialysis (ED) with monovalent permselective membranes. Coagulation with ferric salts is highly efficient at removing arsenic from RO concentrate to meet a drinking water standard of 10 μg/L. The chemical demand for ferric chloride however is much lower than ferric sulfate as coagulant. An alternative method using ferric sludge from surface water treatment plant is demonstrated as an efficient adsorbent to remove arsenic from RO concentrate, providing a promising low cost, "waste treat waste" approach. The monovalent permselective anion exchange membranes exhibit high selectivity in removing monovalent anions over di- and multi-valent anions. The transport of sulfate and phosphate through the anion exchange membranes was negligible over a broad range of electrical current density. However, the transport of divalent cations such as calcium and magnesium increases through monovalent permselective cation exchange membranes with increasing current density. Higher overall salt concentration reduction is achieved around limiting current density while higher normalized salt removal rate in terms of mass of salt per membrane area and applied energy is attained at lower current density because the energy unitization efficiency decreases at higher current density. Copyright © 2013 Elsevier B.V. All rights reserved.

Perennial water stratification and the role of freshwater in the mass balance of Arctic ice shelves and multiyear landfast sea ice

International Nuclear Information System (INIS)

Jeffries, M.O.

1991-01-01

A number of the ice shelves of northern Ellesmere Island in the Canadian High Arctic owe their origin to multiyear landfast sea ice (MLSI) growth during the post-Hypsithermal cooling ca. 3,000-4,000 BP. Since they grew in response to an arctic-wide climatic deterioration and contain evidence of occasional post-4,000 BP climatic ameliorations, they may be expected to be sensitive to future global climate changes manifested in the High Arctic. The purpose of this paper is to examine ice-ocean interactions and feedbacks, and the response of the ice shelves and the MLSI to the improved summer climate of the last ca. 100 years, and implications for the future. There is good evidence that there has been a negative surface mass balance since the turn of the century. Mass balance measurements on the Ward Hunt Ice Shelf between 1966 and 1985 indicate a total ice loss of 1.371 m at a mean annual rate of 68.5 mm. The interannual pattern of accumulation and ablation and the long-term losses on the ice shelf are similar to other Canadian High Arctic glacier mass balance records. It is evident from water and ice core records of salinity, δ 18 0 and tritium, that perennial water stratification is common below and behind the ice shelves and MLSI. The coastal waters are highly stratified, with anything from 0.5 m to 41.0 m of freshwater interposed between the overlying ice and underlying seawater. The primary source of the freshwater is summer run-off of snow-meltwater from the adjacent land and from the ice itself. There is minimal mixing between the influent freshwater and seawater, and the freshwater is either dammed behind the ice shelves and the MLSI, with subsequent under-ice freshwater outflows, or pooled in under-ice depressions

Seasonally-Active Water on Mars: Vapour, Ice, Adsorbate, and the Possibility of Liquid

Science.gov (United States)

Richardson, M. I.

2002-12-01

Seasonally-active water can be defined to include any water reservoir that communicates with other reservoirs on time scales of a year or shorter. It is the interaction of these water reservoirs, under the influence of varying solar radiation and in conjunction with surface and atmospheric temperatures, that determines the phase-stability field for water at the surface, and the distribution of water in various forms below, on, and above the surface. The atmosphere is the critical, dynamical link in this cycling system, and also (fortunately) one of the easiest to observe. Viking and Mars Global Surveyor observations paint a strongly asymmetric picture of the global seasonal water cycle, tied proximately to planetary eccentricity, and the existence of residual ice caps of different composition at the two poles. The northern summer experiences the largest water vapour columns, and is associated with sublimation from the northern residual water ice cap. The southern summer residual carbon dioxide ice cap is cold trap for water. Asymmetry in the water cycle is an unsolved problem. Possible solutions may involve the current timing of perihelion (the water cap resides at the pole experiencing the longer but cooler summer), the trapping of water ice in the northern hemisphere by tropical water ice clouds, and the bias in the annual-average, zonal-mean atmospheric circulation resulting from the zonal-mean difference in the elevation of the northern and southern hemispheres. Adsorbed and frozen water have proven harder to constrain. Recent Odyssey Gamma Ray Spectrometer results suggest substantial ground ice in the mid- and high-latitudes, but this water is likely below the seasonal skin depth for two reasons: the GRS results are best fit with such a model, and GCM models of the water cycle produce dramatically unrealistic atmospheric vapour distributions when such a very near surface, GRS-like distribution is initialized - ultimately removing the water to the northern and

Gulf-Wide Information System, Environmental Sensitivity Index Brackish Marsh, Geographic NAD83, LDWF (2001) [esi_brackish_marsh_LDWF_2001

Data.gov (United States)

Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) brackish marshes data of coastal Louisiana. The ESI is a classification and ranking system, which...

Annual net ecosystem exchanges of carbon dioxide and methane from a temperate brackish marsh: should the focus of marsh restoration be on brackish environments?

Science.gov (United States)

Windham-Myers, L.; Anderson, F. E.; Bergamaschi, B. A.; Ferner, M. C.; Schile, L. M.; Spinelli, G.

2015-12-01

The exchange and transport of carbon in tidally driven, saline marsh ecosystems provide habitat and trophic support for coastal wildlife and fisheries, while potentially accumulating and storing carbon at some of the highest rates compared to other ecosystems. However, due to the predicted rise in sea level over the next century, the preservation and restoration of estuarine habitats is necessary to compensate for their expected decline. In addition, restoration of these marsh systems can also reduce the impacts of global climate change as they assimilate as much carbon as their freshwater counterparts, while emitting less methane due to the higher concentrations of sulfate in seawater. Unfortunately, in brackish marshes, with salinity concentrations less than 18 parts per thousand (ppt), simple relationships between methane production, salinity and sulfate concentrations are not well known. Here we present the net ecosystem exchange (NEE) of carbon dioxide and methane, as calculated by the eddy covariance method, from a brackish marsh ecosystem in the San Francisco Estuary where salinity ranges from oligohaline (0.5-5 ppt) to mesohaline (5-18 ppt) conditions. Daily rates of carbon dioxide and methane NEE ranged from approximately 10 gC-CO2 m-2 d-1 and 0 mgC-CH4 m-2 d-1, during the winter to -15 gC-CO2 m-2 d-1 and 30 mgC-CH4 m-2 d-1, in the summer growing season. A comparison between similar measurements made from freshwater wetlands in the Sacramento-San Joaquin Delta found that the daily rates of carbon dioxide NEE were similar, but daily rates of methane NEE were just a small fraction (0-15%). Our research also shows that the daily fluxes of carbon dioxide and methane at the brackish marsh were highly variable and may be influenced by the tidal exchanges of seawater. Furthermore, the observed decline in methane production from summer to fall may have resulted from a rise in salinity and/or a seasonal decline in water and air temperatures. Our research goals are

A natural driven membrane process for brackish and wastewater treatment: photovoltaic powered ED and FO hybrid system.

Science.gov (United States)

Zhang, Yang; Pinoy, Luc; Meesschaert, Boudewijn; Van der Bruggen, Bart

2013-09-17

In isolated locations, remote areas, or islands, potable water is precious because of the lack of drinking water treatment facilities and energy supply. Thus, a robust and reliable water treatment system based on natural energy is needed to reuse wastewater or to desalinate groundwater/seawater for provision of drinking water. In this work, a hybrid membrane system combining electrodialysis (ED) and forward osmosis (FO), driven by renewable energy (solar energy), denoted as EDFORD (ED-FO Renewable energy Desalination), is proposed to produce high-quality water (potable) from secondary wastewater effluent or brackish water. In this hybrid membrane system, feedwater (secondary wastewater effluent or synthetic brackish water) was drawn to the FO draw solution while the organic and inorganic substances (ions, compounds, colloids and particles) were rejected. The diluted draw solution was then pumped to the solar energy driven ED. In the ED unit, the diluted draw solution was desalted and high-quality water was produced; the concentrate was recycled to the FO unit and reused as the draw solution. Results show that the water produced from this system contains a low concentration of total organic carbon (TOC), carbonate, and cations derived from the feedwater; had a low conductivity; and meets potable water standards. The water production cost considering the investment for membranes and solar panel is 3.32 to 4.92 EUR m(-3) (for 300 days of production per year) for a small size potable water production system.

Ice and water droplets on graphite: A comparison of quantum and classical simulations

International Nuclear Information System (INIS)

Ramírez, Rafael; Singh, Jayant K.; Müller-Plathe, Florian; Böhm, Michael C.

2014-01-01

Ice and water droplets on graphite have been studied by quantum path integral and classical molecular dynamics simulations. The point-charge q-TIP4P/F potential was used to model the interaction between flexible water molecules, while the water-graphite interaction was described by a Lennard-Jones potential previously used to reproduce the macroscopic contact angle of water droplets on graphite. Several energetic and structural properties of water droplets with sizes between 10 2 and 10 3 molecules were analyzed in a temperature interval of 50–350 K. The vibrational density of states of crystalline and amorphous ice drops was correlated to the one of ice Ih to assess the influence of the droplet interface and molecular disorder on the vibrational properties. The average distance of covalent OH bonds is found 0.01 Å larger in the quantum limit than in the classical one. The OO distances are elongated by 0.03 Å in the quantum simulations at 50 K. Bond distance fluctuations are large as a consequence of the zero-point vibrations. The analysis of the H-bond network shows that the liquid droplet is more structured in the classical limit than in the quantum case. The average kinetic and potential energy of the ice and water droplets on graphite has been compared with the values of ice Ih and liquid water as a function of temperature. The droplet kinetic energy shows a temperature dependence similar to the one of liquid water, without apparent discontinuity at temperatures where the droplet is solid. However, the droplet potential energy becomes significantly larger than the one of ice or water at the same temperature. In the quantum limit, the ice droplet is more expanded than in a classical description. Liquid droplets display identical density profiles and liquid-vapor interfaces in the quantum and classical limits. The value of the contact angle is not influenced by quantum effects. Contact angles of droplets decrease as the size of the water droplet increases

Late rise in hemolymph osmolality in Macrobrachium acanthurus (diadromous freshwater shrimp) exposed to brackish water: Early reduction in branchial Na+/K+ pump activity but stable muscle HSP70 expression.

Science.gov (United States)

Freire, Carolina A; Maraschi, Anieli C; Lara, Alessandra F; Amado, Enelise M; Prodocimo, Viviane

2018-02-01

Some Macrobrachium shrimps (Caridea, Palaemonidae) are diadromous; freshwater adults are truly euryhaline, while larvae need saline water for development. Branchial Na + /K + -ATPase (NKA) and carbonic anhydrase (CA) are involved in NaCl absorption in freshwater. This study aimed at verifying the time course of the osmoregulatory response of adult Macrobrachium acanthurus to high salinity brackish water (20‰), from the first 30min to 5days. The goal was to detect possible transition from hyper- to hyporegulation, the putative involvement of branchial NKA and CA, or the induction of muscular HSP70 expression. Hemolymph osmotic and ionic concentrations remained relatively stable and close to control levels until ~9h of exposure, but later increased consistently (~50%). A fast reduction in NKA activity (3-6h) was observed; these shrimps seem to shut off salt absorption already in the first hours. Later on, especially after 24h, hemolymph concentrations rise but HSP70 expression is not induced, possibly because constitutive levels are already sufficient to prevent protein damage. Time-dependent response mechanisms effective in high salinity brackish water, resulting in salt loading avoidance and suggestive of hyporegulation should be further investigated in decapods that evolutionary invaded freshwater. Copyright © 2017 Elsevier Inc. All rights reserved.

Improved Instrument for Detecting Water and Ice in Soil

Science.gov (United States)

Buehler, Martin; Chin, Keith; Keymeulen, Didler; McCann, Timothy; Seshadri, Suesh; Anderson, Robert

2009-01-01

An instrument measures electrical properties of relatively dry soils to determine their liquid water and/or ice contents. Designed as a prototype of instruments for measuring the liquid-water and ice contents of lunar and planetary soils, the apparatus could also be utilized for similar purposes in research and agriculture involving terrestrial desert soils and sands, and perhaps for measuring ice buildup on aircraft surfaces. This instrument is an improved version of the apparatus described in Measuring Low Concentrations of Liquid Water and Ice in Soil (NPO-41822), NASA Tech Briefs, Vol. 33, No. 2 (February 2009), page 22. The designs of both versions are based on the fact that the electrical behavior of a typical soil sample is well approximated by a network of resistors and capacitors in which resistances decrease and capacitances increase (and the magnitude and phase angle of impedance changes accordingly) with increasing water content. The previous version included an impedance spectrometer and a jar into which a sample of soil was placed. Four stainless-steel screws at the bottom of the jar were used as electrodes of a fourpoint impedance probe connected to the spectrometer. The present instrument does not include a sample jar and can be operated without acquiring or handling samples. Its impedance probe consists of a compact assembly of electrodes housed near the tip of a cylinder. The electrodes protrude slightly from the cylinder (see Figure 1). In preparation for measurements, the cylinder is simply pushed into the ground to bring the soil into contact with the electrodes.

Circulation and water properties in the landfast ice zone of the Alaskan Beaufort Sea

Science.gov (United States)

Weingartner, Thomas J.; Danielson, Seth L.; Potter, Rachel A.; Trefry, John H.; Mahoney, Andy; Savoie, Mark; Irvine, Cayman; Sousa, Leandra

2017-09-01

Moorings, hydrography, satellite-tracked drifters, and high-frequency radar data describe the annual cycle in circulation and water properties in the landfast ice zone (LIZ) of the Alaskan Beaufort Sea. Three seasons, whose duration and characteristics are controlled by landfast ice formation and ablation, define the LIZ: ;winter;, ;break-up;, and ;open-water;. Winter begins in October with ice formation and ends in June when rivers commence discharging. Winter LIZ ice velocities are zero, under-ice currents are weak ( 5 cm s-1), and poorly correlated with winds and local sea level. The along-shore momentum balance is between along-shore pressure gradients and bottom and ice-ocean friction. Currents at the landfast ice-edge are swift ( 35 cm s-1), wind-driven, with large horizontal shears, and potentially unstable. Weak cross-shore velocities ( 1 cm s-1) imply limited exchanges between the LIZ and the outer shelf in winter. The month-long break-up season (June) begins with the spring freshet and concludes when landfast ice detaches from the bottom. Cross-shore currents increase, and the LIZ hosts shallow ( 2 m), strongly-stratified, buoyant and sediment-laden, under-ice river plumes that overlie a sharp, 1 m thick, pycnocline across which salinity increases by 30. The plume salt balance is between entrainment and cross-shore advection. Break-up is followed by the 3-month long open-water season when currents are swift (≥20 cm s-1) and predominantly wind-driven. Winter water properties are initialized by fall advection and evolve slowly due to salt rejection from ice. Fall waters and ice within the LIZ derive from local rivers, the Mackenzie and/or Chukchi shelves, and the Arctic basin.

Tracing Atlantic Water Signature in the Arctic Sea Ice Cover East of Svalbard

Directory of Open Access Journals (Sweden)

Vladimir V. Ivanov

2012-01-01

Full Text Available We focus on the Arctic Ocean between Svalbard and Franz Joseph Land in order to elucidate the possible role of Atlantic water (AW inflow in shaping ice conditions. Ice conditions substantially affect the temperature regime of the Spitsbergen archipelago, particularly in winter. We test the hypothesis that intensive vertical mixing at the upper AW boundary releases substantial heat upwards that eventually reaches the under-ice water layer, thinning the ice cover. We examine spatial and temporal variation of ice concentration against time series of wind, air temperature, and AW temperature. Analysis of 1979–2011 ice properties revealed a general tendency of decreasing ice concentration that commenced after the mid-1990s. AW temperature time series in Fram Strait feature a monotonic increase after the mid-1990s, consistent with shrinking ice cover. Ice thins due to increased sensible heat flux from AW; ice erosion from below allows wind and local currents to more effectively break ice. The winter spatial pattern of sea ice concentration is collocated with patterns of surface heat flux anomalies. Winter minimum sea ice thickness occurs in the ice pack interior above the AW path, clearly indicating AW influence on ice thickness. Our study indicates that in the AW inflow region heat flux from the ocean reduces the ice thickness.

Synergistic efficiency of the desilication of brackish underground water in Saudi Arabia by coupling γ-radiation and Fenton process: Membrane scaling prevention in reverse osmosis process

Science.gov (United States)

Aljohani, Mohammed S.

2017-12-01

One of the main water resources in arid Saudi Arabia is underground water. However, this brackish water has high silica content which can cause a recalcitrant deposit on the membrane in the reverse osmosis units during its desalination. In this study, we examined the synergistic efficiency of the removal of silica from the Buwaib water sample, when combining two advanced oxidation processes, γ-irradiation and the Fenton process, using hydrogen peroxide and zero valent metal iron as source of Fe3+. This latter adsorbs effectively on silica and co-precipitate. The influence of absorbed dose, iron dosage and pH effect were investigated. This preliminary study showed that these attractive and effective hybrid processes are very efficient in removing silica.

The Large Scale Distribution of Water Ice in the Polar Regions of the Moon

Science.gov (United States)

Jordan, A.; Wilson, J. K.; Schwadron, N.; Spence, H. E.

2017-12-01

For in situ resource utilization, one must know where water ice is on the Moon. Many datasets have revealed both surface deposits of water ice and subsurface deposits of hydrogen near the lunar poles, but it has proved difficult to resolve the differences among the locations of these deposits. Despite these datasets disagreeing on how deposits are distributed on small scales, we show that most of these datasets do agree on the large scale distribution of water ice. We present data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO), LRO's Lunar Exploration Neutron Detector (LEND), the Neutron Spectrometer on Lunar Prospector (LPNS), LRO's Lyman Alpha Mapping Project (LAMP), LRO's Lunar Orbiter Laser Altimeter (LOLA), and Chandrayaan-1's Moon Mineralogy Mapper (M3). All, including those that show clear evidence for water ice, reveal surprisingly similar trends with latitude, suggesting that both surface and subsurface datasets are measuring ice. All show that water ice increases towards the poles, and most demonstrate that its signature appears at about ±70° latitude and increases poleward. This is consistent with simulations of how surface and subsurface cold traps are distributed with latitude. This large scale agreement constrains the origin of the ice, suggesting that an ancient cometary impact (or impacts) created a large scale deposit that has been rendered locally heterogeneous by subsequent impacts. Furthermore, it also shows that water ice may be available down to ±70°—latitudes that are more accessible than the poles for landing.

Patterns of ice nuclei from natural water sources in the mountains of Tirol, Austria

Science.gov (United States)

Baloh, Philipp; Hanlon, Regina; Pietsch, Renee; Anderson, Christopher; Schmale, David G., III; Grothe, Hinrich

2017-04-01

Heterogeneous ice nucleation—the process by which particles can nucleate ice between 0 and -35°C—is important for generating artificial snow. Though abiotic and biotic ice nuclei are present in many different natural and managed ecosystems, little is known about their nature, sources, and ecological roles. We collected samples of water and snow from the mountains of Tyrol, Austria in June, July, and November, 2016. The collected water was mostly from sources with minimal anthropogenic pollution, since most of the water from the sampled streams came from glacial melt. The samples were filtered through a 0.22μm filter, and microorganisms were cultured on different types of media. Resulting colonies were tested for their ice nucleation ability using a droplet freezing assay and identified to the level of the species. The unfiltered water and the filtered water will be subjected to additional assays using cryo microscopy and vibrational microscopy (IR and Raman- spectroscopy). Preliminary analyses suggested that the percentage of ice-nucleating microbes varied with season; greater percentages of ice nucleating microbes were present during colder months. The glacial melt also varies strongly over the year with the fraction of mineral dust suspended in it which serves as an inorganic ice nucleation agent. Further investigation of these samples may help to show the combined ice nuleation abilities of biological and non biological particles present in the mountains of Tirol, Austria. Future work may shed light on how the nucleation properties of the natural water changes with the time of the year and what may be responsible for these changes.

Air-sea flux of CO2 in arctic coastal waters influenced by glacial melt water and sea ice

DEFF Research Database (Denmark)

Sejr, Mikael Kristian; Krause-Jensen, Dorte; Rysgaard, Søren

2011-01-01

Annual air–sea exchange ofCO2 inYoung Sound,NEGreenlandwas estimated using pCO2 surface-water measurements during summer (2006–2009) and during an ice-covered winter 2008. All surface pCO2 values were below atmospheric levels indicating an uptake of atmospheric CO2. During sea ice formation...... and thereby efficiently blocked air–sea CO2 exchange. During sea ice melt, dissolution of CaCO3 combined with primary production and strong stratification of the water column acted to lower surface-water pCO2 levels in the fjord. Also, a large input of glacial melt water containing geochemically reactive...... year-to-year variation in annual gas exchange....

Oxygen exchange and ice melt measured at the ice-water interface by eddy correlation

DEFF Research Database (Denmark)

Long, M.H.; Koopmans, D.; Berg, P.

2012-01-01

heterotrophic with a daily gross primary production of 0.69 mmol O2 mĝ̂'2 dĝ̂'1 and a respiration rate of ĝ̂'2.13 mmol O2 mĝ̂'2 dĝ̂'1 leading to a net ecosystem metabolism of ĝ̂'1.45 mmol O2 mĝ̂'2 dĝ̂'1. This application of the eddy correlation technique produced high temporal resolution O2 fluxes and ice melt......This study examined fluxes across the ice-water interface utilizing the eddy correlation technique. Temperature eddy correlation systems were used to determine rates of ice melting and freezing, and O2 eddy correlation systems were used to examine O2 exchange rates driven by biological and physical...

Observations of the PCB distribution within and in-between ice, snow, ice-rafted debris, ice-interstitial water, and seawater in the Barents Sea marginal ice zone and the North Pole area.

Science.gov (United States)

Gustafsson, O; Andersson, P; Axelman, J; Bucheli, T D; Kömp, P; McLachlan, M S; Sobek, A; Thörngren, J-O

2005-04-15

To evaluate the two hypotheses of locally elevated exposure of persistent organic pollutants (POPs) in ice-associated microenvironments and ice as a key carrier for long-range transport of POPs to the Arctic marginal ice zone (MIZ), dissolved and particulate polychlorinated biphenyls (PCBs) were analyzed in ice, snow, ice-interstitial water (IIW), seawater in the melt layer underlying the ice, and in ice-rafted sediment (IRS) from the Barents Sea MIZ to the high Arctic in the summer of 2001. Ultra-clean sampling equipment and protocols were specially developed for this expedition, including construction of a permanent clean room facility and a stainless steel seawater intake system on the I/B ODEN as well as two mobile 370 l ice-melting systems. Similar concentrations were found in several ice-associated compartments. For instance, the concentration of one of the most abundant congeners, PCB 52, was typically on the order of 0.1-0.3 pg l(-1) in the dissolved (melted) phase of the ice, snow, IIW, and underlying seawater while its particulate organic-carbon (POC) normalized concentrations were around 1-3 ng gPOC(-1) in the ice, snow, IIW, and IRS. The solid-water distribution of PCBs in ice was well correlated with and predictable from K(ow) (ice log K(oc)-log K(ow) regressions: p<0.05, r2=0.78-0.98, n=9), indicating near-equilibrium partitioning of PCBs within each local ice system. These results do generally not evidence the existence of physical microenvironments with locally elevated POP exposures. However, there were some indications that the ice-associated system had harbored local environments with higher exposure levels earlier/before the melting/vegetative season, as a few samples had PCB concentrations elevated by factors of 5-10 relative to the typical values, and the elevated levels were predominantly found at the station where melting had putatively progressed the least. The very low PCB concentrations and absence of any significant concentration

Observations of the PCB distribution within and in-between ice, snow, ice-rafted debris, ice-interstitial water, and seawater in the Barents Sea marginal ice zone and the North Pole area

International Nuclear Information System (INIS)

Gustafsson, Oe.; Andersson, P.; Axelman, J.; Bucheli, T.D.; Koemp, P.; McLachlan, M.S.; Sobek, A.; Thoerngren, J.-O.

2005-01-01

To evaluate the two hypotheses of locally elevated exposure of persistent organic pollutants (POPs) in ice-associated microenvironments and ice as a key carrier for long-range transport of POPs to the Arctic marginal ice zone (MIZ), dissolved and particulate polychlorinated biphenyls (PCBs) were analyzed in ice, snow, ice-interstitial water (IIW), seawater in the melt layer underlying the ice, and in ice-rafted sediment (IRS) from the Barents Sea MIZ to the high Arctic in the summer of 2001. Ultra-clean sampling equipment and protocols were specially developed for this expedition, including construction of a permanent clean room facility and a stainless steel seawater intake system on the I/B ODEN as well as two mobile 370 l ice-melting systems. Similar concentrations were found in several ice-associated compartments. For instance, the concentration of one of the most abundant congeners, PCB 52, was typically on the order of 0.1-0.3 pg l -1 in the dissolved (melted) phase of the ice, snow, IIW, and underlying seawater while its particulate organic-carbon (POC) normalized concentrations were around 1-3 ng gPOC -1 in the ice, snow, IIW, and IRS. The solid-water distribution of PCBs in ice was well correlated with and predictable from K ow (ice log K oc -log K ow regressions: p 2 =0.78-0.98, n=9), indicating near-equilibrium partitioning of PCBs within each local ice system. These results do generally not evidence the existence of physical microenvironments with locally elevated POP exposures. However, there were some indications that the ice-associated system had harbored local environments with higher exposure levels earlier/before the melting/vegetative season, as a few samples had PCB concentrations elevated by factors of 5-10 relative to the typical values, and the elevated levels were predominantly found at the station where melting had putatively progressed the least. The very low PCB concentrations and absence of any significant concentration gradients, both

Satellite altimetry in sea ice regions - detecting open water for estimating sea surface heights

Science.gov (United States)

Müller, Felix L.; Dettmering, Denise; Bosch, Wolfgang

2017-04-01

The Greenland Sea and the Farm Strait are transporting sea ice from the central Arctic ocean southwards. They are covered by a dynamic changing sea ice layer with significant influences on the Earth climate system. Between the sea ice there exist various sized open water areas known as leads, straight lined open water areas, and polynyas exhibiting a circular shape. Identifying these leads by satellite altimetry enables the extraction of sea surface height information. Analyzing the radar echoes, also called waveforms, provides information on the surface backscatter characteristics. For example waveforms reflected by calm water have a very narrow and single-peaked shape. Waveforms reflected by sea ice show more variability due to diffuse scattering. Here we analyze altimeter waveforms from different conventional pulse-limited satellite altimeters to separate open water and sea ice waveforms. An unsupervised classification approach employing partitional clustering algorithms such as K-medoids and memory-based classification methods such as K-nearest neighbor is used. The classification is based on six parameters derived from the waveform's shape, for example the maximum power or the peak's width. The open-water detection is quantitatively compared to SAR images processed while accounting for sea ice motion. The classification results are used to derive information about the temporal evolution of sea ice extent and sea surface heights. They allow to provide evidence on climate change relevant influences as for example Arctic sea level rise due to enhanced melting rates of Greenland's glaciers and an increasing fresh water influx into the Arctic ocean. Additionally, the sea ice cover extent analyzed over a long-time period provides an important indicator for a globally changing climate system.

Water ice clouds observations with PFS on Mars Express

Science.gov (United States)

Moroz, V. I.; Zasova, L. V.; Formisano, V.; Grassi, D.; Ignatiev, N. I.; Giuranna, M.; Maturilli, A.; Pfs Team

The water ice cloud observation is one of the scientific goals of PFS. Presence and properties of the ice particles are identified from absorption features, observed in both spectral ranges of PFS. Being in the near perihelion condition, the temperature of the Martian atmosphere is pretty high and ice clouds exist only in some places, for example, related to topography or at north high latitudes et etc. The ice clouds are observed often above the tops of the volcanoes. We have found the ice clouds above Olympus (orbit 37) and Ascraeus Mons (orbit 68). Effective radius of particles according to the thermal IR is preliminary estimated of 1 μ m, which leads to the visual opacity of 0.2 -0.3 above Olympus and of maximum of 0.6 above Ascraeus Mons. In the case of Ascraeus Mons the ice clouds are observed on the south slope near the top of the volcano. The maximum surface temperature, observed there, results in the upward flux of warm air, which, cooling, provides the condensation of H2O. We will present a detailed analysis of the ice clouds, observed over the planet in the IR spectral range.

Photolytic degradation of methyl-parathion and fenitrothion in ice and water: Implications for cold environments

Energy Technology Data Exchange (ETDEWEB)

Weber, Jan [Lancaster Environment Centre, Centre for Chemicals Management, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Kurkova, Romana; Klanova, Jana [RECETOX, Faculty of Science, Masaryk University, Kamenice 3, 625 00 Brno (Czech Republic); Klan, Petr, E-mail: klan@sci.muni.c [Dept of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A8, 625 00 Brno (Czech Republic); Halsall, Crispin J., E-mail: c.halsall@lancaster.ac.u [Lancaster Environment Centre, Centre for Chemicals Management, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

2009-12-15

Here we investigate the photodegradation of structurally similar organophosphorus pesticides; methyl-parathion and fenitrothion in water (20 deg. C) and ice (-15 deg. C) under environmentally-relevant conditions with the aim of comparing these laboratory findings to limited field observations. Both compounds were found to be photolyzed more efficiently in ice than in aqueous solutions, with quantum yields of degradation being higher in ice than in water (fenitrothion > methyl-parathion). This rather surprising observation was attributed to the concentration effect caused by freezing the aqueous solutions. The major phototransformation products included the corresponding oxons (methyl-paraoxon and fenitroxon) and the nitrophenols (3-methyl-nitrophenol and nitrophenol) in both irradiated water and ice samples. The presence of oxons in ice following irradiation, demonstrates an additional formation mechanism of these toxicologically relevant compounds in cold environments, although further photodegradation of oxons in ice indicates that photochemistry of OPs might be an environmentally important sink in cold environments. - Photodegradation of methyl-parathion and fenitrothion in water and ice under environmentally-relevant conditions is described.

The role of ice dynamics in shaping vegetation in flowing waters.

Science.gov (United States)

Lind, Lovisa; Nilsson, Christer; Polvi, Lina E; Weber, Christine

2014-11-01

Ice dynamics is an important factor affecting vegetation in high-altitude and high-latitude streams and rivers. During the last few decades, knowledge about ice in streams and rivers has increased significantly and a respectable body of literature is now available. Here we review the literature on how ice dynamics influence riparian and aquatic vegetation. Traditionally, plant ecologists have focused their studies on the summer period, largely ignoring the fact that processes during winter also impact vegetation dynamics. For example, the freeze-up period in early winter may result in extensive formation of underwater ice that can restructure the channel, obstruct flow, and cause flooding and thus formation of more ice. In midwinter, slow-flowing reaches develop a surface-ice cover that accumulates snow, protecting habitats under the ice from formation of underwater ice but also reducing underwater light, thus suppressing photosynthesis. Towards the end of winter, ice breaks up and moves downstream. During this transport, ice floes can jam up and cause floods and major erosion. The magnitudes of the floods and their erosive power mainly depend on the size of the watercourse, also resulting in different degrees of disturbance to the vegetation. Vegetation responds both physically and physiologically to ice dynamics. Physical action involves the erosive force of moving ice and damage caused by ground frost, whereas physiological effects - mostly cell damage - happen as a result of plants freezing into the ice. On a community level, large magnitudes of ice dynamics seem to favour species richness, but can be detrimental for individual plants. Human impacts, such as flow regulation, channelisation, agriculturalisation and water pollution have modified ice dynamics; further changes are expected as a result of current and predicted future climate change. Human impacts and climate change can both favour and disfavour riverine vegetation dynamics. Restoration of streams

Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Science.gov (United States)

Jones, Elizabeth M.; Bakker, Dorothee C. E.; Venables, Hugh J.; Whitehouse, Michael J.; Korb, Rebecca E.; Watson, Andrew J.

2010-11-01

ABSTRACT The effect of sea ice melt on the carbonate chemistry of surface waters in the Weddell-Scotia Confluence, Southern Ocean, was investigated during January 2008. Contrasting concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA) and the fugacity of carbon dioxide (fCO2) were observed in and around the receding sea ice edge. The precipitation of carbonate minerals such as ikaite (CaCO3.6H2O) in sea ice brine has the net effect of decreasing DIC and TA and increasing the fCO2 in the brine. Deficits in DIC up to 12 +/- 3 μmol kg-1 in the marginal ice zone (MIZ) were consistent with the release of DIC-poor brines to surface waters during sea ice melt. Biological utilization of carbon was the dominant processes and accounted for 41 +/- 1 μmol kg-1 of the summer DIC deficit. The data suggest that the combined effects of biological carbon uptake and the precipitation of carbonates created substantial undersaturation in fCO2 of 95 μatm in the MIZ during summer sea ice melt. Further work is required to improve the understanding of ikaite chemistry in Antarctic sea ice and its importance for the sea ice carbon pump.

Exospheric transport restrictions on water ice in lunar polar traps

Science.gov (United States)

Hodges, R. R., Jr.

1991-01-01

There is little doubt that at least 10 exp 17 g of water has accreted on the moon as a result of the reduction of ferric iron at the regolith surface by solar wind protons, the vaporization of chondrites, and perhaps comet impacts. Lacking an efficient escape mechanism, most of this water (or its progeny) is probably on the moon now. If the water were to have migrated to permanently shaded cold traps near the lunar poles, ice deposts with densities greater than 1000 g/sq cm would cover the traps, providing accessible resources. However, exospheric transport considerations suggest that the actual amount of water ice in the cold traps is probably too small to be of practical interest. The alternative is global assimilation of most of the water into the regolith, a process that must account for about 30 micromoles of water per gram of soil.

Sea ice - Multiyear cycles and white ice

Science.gov (United States)

Ledley, T. S.

1985-01-01

The multiyear thickness cycles represent one of the interesting features of the sea ice studies performed by Semtner (1976) and Washington et al. (1976) with simple thermodynamic models of sea ice. In the present article, a description is given of results which show that the insulating effect of snow on the surface of the sea ice is important in producing these multiyear cycles given the physics included in the model. However, when the formation of white ice is included, the cycles almost disappear. White ice is the ice which forms at the snow-ice interface when the snow layer becomes thick enough to depress the ice below the water level. Water infiltrates the snow by coming through the ice at leads and generally freezes there, forming white ice.

Radiation Effects in Hydrogen-Laden Porous Water Ice Films: Implications for Interstellar Ices

Science.gov (United States)

Raut, Ujjwal; Baragiola, Raul; Mitchell, Emma; Shi, Jianming

H _{2} molar remains trapped in the ice even upon removal of ambient gas-phase H _{2}, and is stable to 170 K, where the ice film desorbs. We will describe the dependence of net loss of adsorbed hydrogen on important parameters such as ice film thickness and the ratio of ion flux (f) to H _{2} flux (F _{H}). Both fluxes are higher by orders of magnitude than interstellar values. However, the information obtained from these experiments, especially the behavior in the limit of low flux (f Journal, 1983. 275: p. 391-404. 3.Shi, J., B.D. Teolis, and R.A. Baragiola, Irradiation-enhanced adsorption and trapping of O2 on nanoporous water ice. Physical Review B, 2009. 79(23): p. 235422. 4.Raut, U., et al., Compaction of microporous amorphous solid water by ion irradiation. Journal of Chemical Physics, 2007. 126(24): p. 244511.

Thermal desorption of formamide and methylamine from graphite and amorphous water ice surfaces

Science.gov (United States)

Chaabouni, H.; Diana, S.; Nguyen, T.; Dulieu, F.

2018-04-01

Context. Formamide (NH2CHO) and methylamine (CH3NH2) are known to be the most abundant amine-containing molecules in many astrophysical environments. The presence of these molecules in the gas phase may result from thermal desorption of interstellar ices. Aims: The aim of this work is to determine the values of the desorption energies of formamide and methylamine from analogues of interstellar dust grain surfaces and to understand their interaction with water ice. Methods: Temperature programmed desorption (TPD) experiments of formamide and methylamine ices were performed in the sub-monolayer and monolayer regimes on graphite (HOPG) and non-porous amorphous solid water (np-ASW) ice surfaces at temperatures 40-240 K. The desorption energy distributions of these two molecules were calculated from TPD measurements using a set of independent Polanyi-Wigner equations. Results: The maximum of the desorption of formamide from both graphite and ASW ice surfaces occurs at 176 K after the desorption of H2O molecules, whereas the desorption profile of methylamine depends strongly on the substrate. Solid methylamine starts to desorb below 100 K from the graphite surface. Its desorption from the water ice surface occurs after 120 K and stops during the water ice sublimation around 150 K. It continues to desorb from the graphite surface at temperatures higher than160 K. Conclusions: More than 95% of solid NH2CHO diffuses through the np-ASW ice surface towards the graphitic substrate and is released into the gas phase with a desorption energy distribution Edes = 7460-9380 K, which is measured with the best-fit pre-exponential factor A = 1018 s-1. However, the desorption energy distribution of methylamine from the np-ASW ice surface (Edes = 3850-8420 K) is measured with the best-fit pre-exponential factor A = 1012 s-1. A fraction of solid methylamine monolayer of roughly 0.15 diffuses through the water ice surface towards the HOPG substrate. This small amount of methylamine

EPR Evidence of Liquid Water in Ice: An Intrinsic Property of Water or a Self-Confinement Effect?

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Thangswamy, Muthulakshmi; Maheshwari, Priya; Dutta, Dhanadeep; Rane, Vinayak; Pujari, Pradeep K

2018-06-01

Liquid water (LW) existence in pure ice below 273 K has been a controversial aspect primarily because of the lack of experimental evidence. Recently, electron paramagnetic resonance (EPR) has been used to study deeply supercooled water in a rapidly frozen polycrystalline ice. The same technique can also be used to probe the presence of LW in polycrystalline ice that has formed through a more conventional, slow cooling one. In this context, the present study aims to emphasize that in case of an external probe involving techniques such as EPR, the results are influenced by the binary phase (BP) diagram of the probe-water system, which also predicts the existence of LW domains in ice, up to the eutectic point. Here we report the results of our such EPR spin-probe studies on water, which demonstrate that smaller the concentration of the probe stronger is the EPR evidence of liquid domains in polycrystalline ice. We used computer simulations based on stochastic Liouville theory to analyze the lineshapes of the EPR spectra. We show that the presence of the spin probe modifies the BP diagram of water, at very low concentrations of the spin probe. The spin probe thus acts, not like a passive reporter of the behavior of the solvent and its environment, but as an active impurity to influence the solvent. We show that there exists a lower critical concentration, below which BP diagram needs to be modified, by incorporating the effect of confinement of the spin probe. With this approach, we demonstrate that the observed EPR evidence of LW domains in ice can be accounted for by the modified BP diagram of the probe-water system. The present work highlights the importance of taking cognizance of the possibility of spin probes affecting the host systems, when interpreting the EPR (or any other probe based spectroscopic) results of phase transitions of host, as its ignorance may lead to serious misinterpretations.

Hepatic pathologies in the brackish water catfish (Chrysichthys nigrodigitatus) from contaminated locations of the Lagos lagoon complex

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Olarinmoye, O.; Taiwo, V.; Clarke, E.; Kumolu-Johnson, C.; Aderinola, O.; Adekunbi, F.

2010-01-01

Several toxicological studies into the effects of aquatic pollutants on the liver of teleost fish exist in literature. The focus on the liver in these studies is predicated on its central nature in the scheme of biotransformation and excretion of xenobiotics following exposure in polluted water bodies. As a consequence of the latter primary role of the liver in these processes it is regarded as a predilective site for the sub lethal effects of xenobiotics on the organism usually detectable at histological level. Hepatic histopathology recorded in livers from feral populations of the brackish water catfish Chrysichthys nigrodigitatus from locations on the Lagos lagoon complex with significant anthropogenic inputs from denizen populations and industries are presented. Liver sections from sixty specimens from two locations on the Lagos lagoon complex (Badagry lagoon: 6??24'N, 2??56'E; and Lagos lagoon: 6??29'N, 3??22'E) were analysed. Observed pathologies included hydropic degeneration (58%), portal / sinusoidal congestion (33%), hepatic necrosis (26%), hemosiderosis (12%) and foci of cellular alterations (FCA's). No obvious oncologic features were observed; the presence of the hydropic Vacuolation lesion was taken as prelude to the development of neoplasms and discussed as such. ?? 2009, Penkala Bt., Budapest, Hungary.

Bacterial activity in sea ice and open water of the Weddell Sea, Antarctica: A microautoradiographic study.

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Grossmann, S

1994-07-01

Metabolic activity of bacteria was investigated in open water, newly forming sea ice, and successive stages of pack ice in the Weddell Sea. Microautoradiography, using [(3)H]leucine as substrate, was compared with incorporation rates of [(3)H]leucine into proteins. Relation of [(3)H]leucine incorporation to the biomass of active bacteria provides information about changes of specific metabolic activity of cells. During a phytoplankton bloom in an ice-free, stratified water column, total numbers of bacteria in the euphotic zone averaged 2.3 × 10(5) ml(-1), but only about 13% showed activity via leucine uptake. Growth rate of the active bacteria was estimated as 0.3-0.4 days(-1). Total cell concentration of bacteria in 400 m depth was 6.6 × 10(4) ml(-1). Nearly 50% of these cells were active, although biomass production and specific growth rate were only about one-tenth that of the surface populations. When sea ice was forming in high concentrations of phytoplankton, bacterial biomass in the newly formed ice was 49.1 ng C ml(-1), exceeding that in open water by about one order of magnitude. Attachment of large bacteria to algal cells seems to cause their enrichment in the new ice, since specific bacterial activity was reduced during ice formation, and enrichment of bacteria was not observed when ice formed at low algal concentration. During growth of pack ice, biomass of bacteria increased within the brine channel system. Specific activity was still reduced at these later stages of ice development, and percentages of active cells were as low as 3-5%. In old, thick pack ice, bacterial activity was high and about 30% of cells were active. However, biomass-specific activity of bacteria remained significantly lower than that in open water. It is concluded that bacterial assemblages different to those of open water developed within the ice and were dominated by bacteria with lower average metabolic activity than those of ice-free water.

Bio-optical properties of Arctic drift ice and surface waters north of Svalbard from winter to spring

Science.gov (United States)

Kowalczuk, Piotr; Meler, Justyna; Kauko, Hanna M.; Pavlov, Alexey K.; Zabłocka, Monika; Peeken, Ilka; Dybwad, Christine; Castellani, Giulia; Granskog, Mats A.

2017-06-01

We have quantified absorption by CDOM, aCDOM(λ), particulate matter, ap(λ), algal pigments, aph(λ), and detrital material, aNAP(λ), coincident with chlorophyll a in sea ice and surface waters in winter and spring 2015 in the Arctic Ocean north of Svalbard. The aCDOM(λ) was low in contrast to other regions of the Arctic Ocean, while ap(λ) has the largest contribution to absorption variability in sea ice and surface waters. ap(443) was 1.4-2.8 times and 1.3-1.8 times higher than aCDOM(443) in surface water and sea ice, respectively. aph(λ) contributed 90% and 81% to ap(λ), in open leads and under-ice waters column, and much less (53%-74%) in sea ice, respectively. Both aCDOM(λ) and ap(λ) followed closely the vertical distribution of chlorophyll a in sea ice and the water column. We observed a tenfold increase of the chlorophyll a concentration and nearly twofold increase in absorption at 443 nm in sea ice from winter to spring. The aCDOM(λ) dominated the absorption budget in the UV both in sea ice and surface waters. In the visible range, absorption was dominated by aph(λ), which contributed more than 50% and aCDOM(λ), which contributed 43% to total absorption in water column. Detrital absorption contributed significantly (33%) only in surface ice layer. Algae dynamics explained more than 90% variability in ap(λ) and aph(λ) in water column, but less than 70% in the sea ice. This study presents detailed absorption budget that is relevant for modeling of radiative transfer and primary production.

Vertical Distribution of Dust and Water Ice Aerosols from CRISM Limb-geometry Observations

Science.gov (United States)

Smith, Michael Doyle; Wolff, Michael J.; Clancy, Todd; Kleinbohl, Armin; Murchie, Scott L.

2013-01-01

[1] Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconnaissance Orbiter provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb enables the vertical distribution of both dust and water ice aerosols to be retrieved. More than a dozen sets of CRISM limb observations have been taken so far providing pole-to-pole cross sections, spanning more than a full Martian year. Radiative transfer modeling is used to model the observations taking into account multiple scattering from aerosols and the spherical geometry of the limb observations. Both dust and water ice vertical profiles often show a significant vertical structure for nearly all seasons and latitudes that is not consistent with the well-mixed or Conrath-v assumptions that have often been used in the past for describing aerosol vertical profiles for retrieval and modeling purposes. Significant variations are seen in the retrieved vertical profiles of dust and water ice aerosol as a function of season. Dust typically extends to higher altitudes (approx. 40-50km) during the perihelion season than during the aphelion season (water ice clouds are common, and water ice aerosols are observed to cap the dust layer in all seasons.

Radar and infrared remote sensing of terrain, water resources, arctic sea ice, and agriculture

Science.gov (United States)

Biggs, A. W.

1983-01-01

Radar range measurements, basic waveforms of radar systems, and radar displays are initially described. These are followed by backscatter from several types of terrain and vegetation as a function of frequency and grazing angle. Analytical models for this backscatter include the facet models of radar return, with range-angle, velocity-range, velocity-angle, range, velocity, and angular only discriminations. Several side-looking airborne radar geometries are presented. Radar images of Arctic sea ice, fresh water lake ice, cloud-covered terrain, and related areas are presented to identify applications of radar imagery. Volume scatter models are applied to radar imagery from alpine snowfields. Short pulse ice thickness radar for subsurface probes is discussed in fresh-water ice and sea ice detection. Infrared scanners, including multispectral, are described. Diffusion of cold water into a river, Arctic sea ice, power plant discharges, volcanic heat, and related areas are presented in thermal imagery. Multispectral radar and infrared imagery are discussed, with comparisons of photographic, infrared, and radar imagery of the same terrain or subjects.

The barrier to ice nucleation in monatomic water

Science.gov (United States)

Prestipino, Santi

2018-03-01

Crystallization from a supercooled liquid initially proceeds via the formation of a small solid embryo (nucleus), which requires surmounting an activation barrier. This phenomenon is most easily studied by numerical simulation, using specialized biased-sampling techniques to overcome the limitations imposed by the rarity of nucleation events. Here, I focus on the barrier to homogeneous ice nucleation in supercooled water, as represented by the monatomic-water model, which in the bulk exhibits a complex interplay between different ice structures. I consider various protocols to identify solidlike particles on a computer, which perform well enough for the Lennard-Jones model, and compare their respective impact on the shape and height of the nucleation barrier. It turns out that the effect is stronger on the nucleus size than on the barrier height. As a by-product of the analysis, I determine the structure of the nucleation cluster, finding that the relative amount of ice phases in the cluster heavily depends on the method used for classifying solidlike particles. Moreover, the phase which is most favored during the earlier stages of crystallization may happen, depending on the nucleation coordinate adopted, to be different from the stable polymorph. Therefore, the quality of a reaction coordinate cannot be assessed simply on the basis of the barrier height obtained. I explain how this outcome is possible and why it just points out the shortcoming of collective variables appropriate to simple fluids in providing a robust method of particle classification for monatomic water.

Ice formation and growth shape bacterial community structure in Baltic Sea drift ice.

Science.gov (United States)

Eronen-Rasimus, Eeva; Lyra, Christina; Rintala, Janne-Markus; Jürgens, Klaus; Ikonen, Vilma; Kaartokallio, Hermanni

2015-02-01

Drift ice, open water and under-ice water bacterial communities covering several developmental stages from open water to thick ice were studied in the northern Baltic Sea. The bacterial communities were assessed with 16S rRNA gene terminal-restriction fragment length polymorphism and cloning, together with bacterial abundance and production measurements. In the early stages, open water and pancake ice were dominated by Alphaproteobacteria and Actinobacteria, which are common bacterial groups in Baltic Sea wintertime surface waters. The pancake ice bacterial communities were similar to the open-water communities, suggesting that the parent water determines the sea-ice bacterial community in the early stages of sea-ice formation. In consolidated young and thick ice, the bacterial communities were significantly different from water bacterial communities as well as from each other, indicating community development in Baltic Sea drift ice along with ice-type changes. The thick ice was dominated by typical sea-ice genera from classes Flavobacteria and Gammaproteobacteria, similar to those in polar sea-ice bacterial communities. Since the thick ice bacterial community was remarkably different from that of the parent seawater, results indicate that thick ice bacterial communities were recruited from the rarer members of the seawater bacterial community. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Case Study of a Small Scale Reverse Osmosis System for Treatment of Mixed Brackish Water and STP Effluent

Directory of Open Access Journals (Sweden)

I Nyoman Widiasa

2017-04-01

Full Text Available A case study on utilizing reverse osmosis (RO technology to fulfill fresh water needs at a mall and a hotel has been done on Bali Island, Indonesia. A mix of brackish water and sewage treatment plant (STP effluent was used as feed water in the RO system. The system used 36 membrane elements (CSM RE 8040 BLN arranged into two stages: 8 pressure vessels (PVs in the first stage and 4 PVs in the second stage, each loaded with 3 membranes. The objectives of this research were to assess the cleaning effectivity in the plant, to evaluate the cleaning of 1 membrane element using a CIP system, and to assess the use of the membrane for filtration in the pre-treatment system. SEM and FTIR analysis indicated that the foulants on the membrane surface were dominated by organic foulants and inorganic deposits. To clean the discarded membrane the proposed method used NaOH solution (pH 12 and pH 13 and citric acid (pH 2 and pH 3. All membranes displayed a dramatic decline in rejection of about 80%. Based on the rejection tests of SO42-, Cl-, turbidity reduction approached 100%. It can be concluded that an RO membrane that has undergone selectivity decline can be re-used as a filtration membrane in the pre-treatment system.

Microwave radiometric aircraft observations of the Fabry-Perot interference fringes of an ice-water system

Science.gov (United States)

Harrington, R. F.; Swift, C. T.; Fedors, J. C.

1980-01-01

Airborne stepped-frequency microwave radiometer (SFMR) observations of the Fabry-Perot interference fringes of ice-water systems are discussed. The microwave emissivity at normal incidence of a smooth layered dielectric medium over a semi-infinite dielectric medium is examined for the case of ice over water as a function of ice thickness and attenuation coefficient, and the presence of quarter-wavelength oscillations in emissivity as the ice thickness and frequency are varied is pointed out. Experimental observations of pronounced quarter-wavelength oscillations in radiometric brightness temperature due to the Fabry-Perot interference fringes over smooth sea ice and lake ice varying in roughness as the radiometer frequencies were scanned are then presented.

Possible significance of cubic water-ice, H2O-Ic, in the atmospheric water cycle of Mars

Science.gov (United States)

Gooding, James L.

1988-01-01

The possible formation and potential significance of the cubic ice polymorph on Mars is discussed. When water-ice crystallizes on Earth, the ambient conditions of temperature and pressure result in the formation of the hexagonal ice polymorph; however, on Mars, the much lower termperature and pressures may permit the crystallization of the cubic polymorph. Cubic ice has two properties of possible importance on Mars: it is an excellant nucleator of other volatiles (such as CO2), and it undergoes an exothermic transition to hexagonal ice at temperatures above 170 K. These properties may have significant implications for both martian cloud formation and the development of the seasonal polar caps.

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

Directory of Open Access Journals (Sweden)

E. L. Simpson

2018-05-01

Full Text Available The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP, which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

Competition for water vapour results in suppression of ice formation in mixed-phase clouds

Science.gov (United States)

Simpson, Emma L.; Connolly, Paul J.; McFiggans, Gordon

2018-05-01

The formation of ice in clouds can initiate precipitation and influence a cloud's reflectivity and lifetime, affecting climate to a highly uncertain degree. Nucleation of ice at elevated temperatures requires an ice nucleating particle (INP), which results in so-called heterogeneous freezing. Previously reported measurements for the ability of a particle to nucleate ice have been made in the absence of other aerosol which will act as cloud condensation nuclei (CCN) and are ubiquitous in the atmosphere. Here we show that CCN can outcompete INPs for available water vapour thus suppressing ice formation, which has the potential to significantly affect the Earth's radiation budget. The magnitude of this suppression is shown to be dependent on the mass of condensed water required for freezing. Here we show that ice formation in a state-of-the-art cloud parcel model is strongly dependent on the criteria for heterogeneous freezing selected from those previously hypothesised. We have developed an alternative criteria which agrees well with observations from cloud chamber experiments. This study demonstrates the dominant role that competition for water vapour can play in ice formation, highlighting both a need for clarity in the requirements for heterogeneous freezing and for measurements under atmospherically appropriate conditions.

Sea-ice cover in the Nordic Seas and the sensitivity to Atlantic water temperatures

Science.gov (United States)

Jensen, Mari F.; Nisancioglu, Kerim H.; Spall, Michael A.

2017-04-01

Changes in the sea-ice cover of the Nordic Seas have been proposed to play a key role for the dramatic temperature excursions associated with the Dansgaard-Oeschger events during the last glacial. However, with its proximity to the warm Atlantic water, how a sea-ice cover can persist in the Nordic Seas is not well understood. In this study, we apply an eddy-resolving configuration of the Massachusetts Institute of Technology general circulation model with an idealized topography to study the presence of sea ice in a Nordic Seas-like domain. We assume an infinite amount of warm Atlantic water present in the south by restoring the southern area to constant temperatures. The sea-surface temperatures are restored toward cold, atmospheric temperatures, and as a result, sea ice is present in the interior of the domain. However, the sea-ice cover in the margins of the Nordic Seas, an area with a warm, cyclonic boundary current, is sensitive to the amount of heat entering the domain, i.e., the restoring temperature in the south. When the temperature of the warm, cyclonic boundary current is high, the margins are free of sea ice and heat is released to the atmosphere. We show that with a small reduction in the temperature of the incoming Atlantic water, the Nordic Seas-like domain is fully covered in sea ice. Warm water is still entering the Nordic Seas, however, this happens at depths below a cold, fresh surface layer produced by melted sea ice. Consequently, the heat release to the atmosphere is reduced along with the eddy heat fluxes. Results suggest a threshold value in the amount of heat entering the Nordic Seas before the sea-ice cover disappears in the margins. We study the sensitivity of this threshold to changes in atmospheric temperatures and vertical diffusivity.

Modelling of destructive ability of water-ice-jet while machine processing of machine elements

Directory of Open Access Journals (Sweden)

Burnashov Mikhail

2017-01-01

Full Text Available This paper represents the classification of the most common contaminants, appearing on the surfaces of machine elements after a long-term service.The existing well-known surface cleaning methods are described and analyzed in the framework of this paper. The article is intended to provide the reader with an understanding of the process of cleaning and removing contamination from machine elements surface by means of water-ice-jet with preprepared beforehand particles, as well as the process of water-ice-jet formation. The paper deals with the description of such advantages of this method as low costs, wastelessness, high quality of the surface, undergoing processing, minimization of harmful impact upon environment and eco-friendliness, which makes it differ radically from formerly known methods. The scheme of interection between the surface and ice particle is represented. A thermo-physical model of destruction of contaminants by means of a water-ice-jet cleaning technology was developed on its basis. The thermo-physical model allows us to make setting of processing mode and the parameters of water-ice-jet scientifically substantiated and well-grounded.

Study on heat transfer performance of water-borne and oily graphene coatings using anti-/de-icing component

Science.gov (United States)

Chen, Long; Zhang, Yidu; Wu, Qiong; Jie, Zhang

2018-02-01

A graphene coating anti-/de-icing experiment was proposed by employing water-borne and oily graphene coatings on the composite material anti-/de-icing component. Considering the characteristics of helicopter rotor sensitivity to icing, a new graphene coating enhancing thermal conductivity of anti-/de-icing component was proposed. The anti-/de-icing experiment was conducted to validate the effectiveness of graphene coating. The results of the experiment show that the graphene coatings play a prominent role in controlling the heat transfer of anti-/de-icing component. The anti-/de-icing effect of oily graphene coating is superior to water-borne graphene.

Ice Water Classification Using Statistical Distribution Based Conditional Random Fields in RADARSAT-2 Dual Polarization Imagery

Science.gov (United States)

Zhang, Y.; Li, F.; Zhang, S.; Hao, W.; Zhu, T.; Yuan, L.; Xiao, F.

2017-09-01

In this paper, Statistical Distribution based Conditional Random Fields (STA-CRF) algorithm is exploited for improving marginal ice-water classification. Pixel level ice concentration is presented as the comparison of methods based on CRF. Furthermore, in order to explore the effective statistical distribution model to be integrated into STA-CRF, five statistical distribution models are investigated. The STA-CRF methods are tested on 2 scenes around Prydz Bay and Adélie Depression, where contain a variety of ice types during melt season. Experimental results indicate that the proposed method can resolve sea ice edge well in Marginal Ice Zone (MIZ) and show a robust distinction of ice and water.

Heavy ion irradiation of crystalline water ice. Cosmic ray amorphisation cross-section and sputtering yield

Science.gov (United States)

Dartois, E.; Augé, B.; Boduch, P.; Brunetto, R.; Chabot, M.; Domaracka, A.; Ding, J. J.; Kamalou, O.; Lv, X. Y.; Rothard, H.; da Silveira, E. F.; Thomas, J. C.

2015-04-01

Context. Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims: We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. Methods: We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results: The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions: The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice sputtering rates compete with the UV photodesorption yields reported in the literature. The prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices. Experiments performed at the Grand Accélérateur National d'Ions Lourds (GANIL) Caen, France. Part of this work has been financed by the French INSU-CNRS programme "Physique et Chimie du Milieu Interstellaire" (PCMI) and the ANR IGLIAS.

Water Ice Clouds and Dust in the Martian Atmosphere Observed by Mars Climate Sounder

Science.gov (United States)

Benson, Jennifer L.; Kass, David; Heavens, Nicholas; Kleinbohl, Armin

2011-01-01

The water ice clouds are primarily controlled by the temperature structure and form at the water condensation level. Clouds in all regions presented show day/night differences. Cloud altitude varies between night and day in the SPH and tropics: (1) NPH water ice opacity is greater at night than day at some seasons (2) The diurnal thermal tide controls the daily variability. (3) Strong day/night changes indicate that the amount of gas in the atmosphere varies significantly. See significant mixtures of dust and ice at the same altitude planet-wide (1) Points to a complex radiative and thermal balance between dust heating (in the visible) and ice heating or cooling in the infrared. Aerosol layering: (1) Early seasons reveal a zonally banded spatial distribution (2) Some localized longitudinal structure of aerosol layers (3) Later seasons show no consistent large scale organization

Experimental investigation of ice and snow melting process on pavement utilizing geothermal tail water

International Nuclear Information System (INIS)

Wang Huajun; Zhao Jun; Chen Zhihao

2008-01-01

Road ice and snow melting based on low temperature geothermal tail water is of significance to realize energy cascading utilization. A small scale ice and snow melting system is built in this work. Experiments of dynamic melting processes of crushed ice, solid ice, artificial snow and natural snow are conducted on concrete pavement. The results show that the melting process of ice and snow includes three phases: a starting period, a linear period and an accelerated period. The critical value of the snow free area ratio between the linear period and the accelerated period is about 0.6. The physical properties of ice and snow, linked with ambient conditions, have an obvious effect on the melting process. The difference of melting velocity and melting time between ice and snow is compared. To reduce energy consumption, the formation of ice on roads should be avoided if possible. The idling process is an effective pathway to improve the performance of melting systems. It is feasible to utilize geothermal tail water of about 40 deg. C for melting ice and snow on winter roads, and it is unnecessary to keep too high fluid temperatures during the practical design and applications. Besides, with the exception of solid ice, the density and porosity of snow and ice tend to be decreasing and increasing, respectively, as the ambient temperature decreases

L-band radiometry for sea ice applications

Science.gov (United States)

Heygster, G.; Hedricks, S.; Mills, P.; Kaleschke, L.; Stammer, D.; Tonboe, R.

2009-04-01

Peake (1976). This expression was used by Menashi et al. (1993) to derive the thickness of sea ice from UHF (0.6 GHz) radiometer. Second, retrieval algorithms for sea ice parameters with emphasis on ice-water discrimination from L-band observations considering the specific SMOS observations modes and geometries are investigated. A modified Menashi model with the permittivity depending on brine volume and temperature suggests a thickness sensitivity of up to 150 cm for low salinity (multi year or brackish) sea ice at low temperatures. At temperatures approaching the melting point the thickness sensitivity reduces to a few centimetres. For first year ice the modelled thickness sensitivity is roughly half a meter. Runs of the model MEMLS with input data generated from a 1-d thermodynamic sea ice model lead to similar conclusio. The results of the forward model may strongly vary with the input microphysical details. E.g. if the permittivity is modelled to depend in addition on the sea ice thickness as supported by several former field campaigns for thin ice, the model predictions change strongly. Prior to the launch of SMOS, an important source of observational data is the SMOS Sea-Ice campaign held near Kokkola, Finland, March 2007 conducted as an add-on of the POL-ICE campaign. Co-incident L-band observations taken with the EMIRAD instrument of the Technical University of Denmark, ice thickness values determined from the EM bird of AWI and in situ observations during the campaign are combined. Although the campaign data are to be use with care, for selected parts of the flights the sea ice thickness can be retrieved correctly. However, as the instrumental conditions and calibration were not optimal, more in situ data, preferably from the Arctic, will be needed before drawing clear conclusions about a future the sea ice thickness product based on SMOS data. Use of additional information from other microwave sensors like AMSR-E might be needed to constrain the conditions, e

Oxo Crater on (1) Ceres: Geological History and the Role of Water-ice

Energy Technology Data Exchange (ETDEWEB)

Nathues, A.; Platz, T.; Hoffmann, M.; Thangjam, G.; Le Corre, L.; Reddy, V. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Goettingen (Germany); Cloutis, E. A.; Applin, D. M. [University of Winnipeg, Winnipeg, MB R3B 2E9 (Canada); Mengel, K. [IELF, TU Clausthal, Adolph-Roemer-Straße 2A, D-38678 Clausthal-Zellerfeld (Germany); Protopapa, S. [University of Maryland, Department of Astronomy, College Park, MD 20742 (United States); Takir, D. [SETI Institute, Mountain View, CA 94043 (United States); Preusker, F. [German Aerospace Center (DLR), Institute of Planetary Research, D-12489 Berlin (Germany); Schmidt, B. E. [Georgia Institute of Technology, Atlanta, GA (United States); Russell, C. T., E-mail: nathues@mps.mpg.de [Institute of Geophysics and Planetary Physics, Dept. of Earth, Planetary and Space Sciences, University of California Los Angeles, Los Angeles, CA (United States)

2017-09-01

Dwarf planet Ceres (∅ ∼ 940 km) is the largest object in the main asteroid belt. Investigations suggest that Ceres is a thermally evolved, volatile-rich body with potential geological activity, a body that was never completely molten, but one that possibly partially differentiated into a rocky core and an ice-rich mantle, and may contain remnant internal liquid water. Thermal alteration and the infall of exogenic material contribute to producing a (dark) carbonaceous chondritic-like surface containing ammoniated phyllosilicates. Here we report imaging and spectroscopic analyses of data on the bright Oxo crater derived from the Framing Camera and the Visible and Infrared Spectrometer on board the Dawn spacecraft. We confirm that the transitional complex crater Oxo (∅ ∼ 9 km) exhibits exposed surface water-ice. We show that this water-ice-rich material is associated exclusively with two lobate deposits at pole-facing scarps, deposits that also contain carbonates and admixed phyllosilicates. Due to Oxo’s location at −4802 m below the cerean reference ellipsoid and its very young age of only 190 ka (1 σ : +100 ka, −70 ka), Oxo is predestined for ongoing water-ice sublimation.

Thermodynamical effects accompanied freezing of two water layers separated by sea ice sheet

Science.gov (United States)

Bogorodsky, Petr; Marchenko, Aleksey

2014-05-01

The process of melt pond freezing is very important for generation of sea ice cover thermodynamic and mass balance during winterperiod. However, due to significant difficulties of field measurements the available data of model estimations still have no instrumental confirmation. In May 2009 the authors carried out laboratory experiment on freezing of limited water volume in the University Centre in Svalbard ice tank. In the course of experiment fresh water layer of 27.5 cm thickness at freezing point poured on the 24 cm sea ice layer was cooled during 50 hours at the temperature -10º C and then once again during 60 hours at -20º C. For revealing process typical characteristics the data of continuous measurements of temperature and salinity in different phases were compared with data of numerical computations obtained with thermodynamic model which was formulated in the frames of 1-D equation system (infinite extension of water freezing layer) and adapted to laboratory conditions. The known surprise of the experiment became proximity of calculated and measured estimates of process dynamics that confirmed the adequacy of the problem mathematical statement (excluding probably process finale stage). This effect can be explained by formation of cracks on the upper layer of ice at sharp decreases of air temperature, which temporary compensated hydrostatic pressure growth during freezing of closed water volume. Another compensated mechanism can be migration of brine through the lower layer of ice under influence of vertical pressure gradient and also rejection of gas dissolved in water which increased its compressibility. During 110 hours cooling thickness of water layer between ice layers reduced approximately to 2 cm. According to computations this layer is not chilled completely but keeps as thin brine interlayer within ice body whose thickness (about units of mm) is determined by temperature fluctuations of cooled surface. Nevertheless, despite good coincidence of

High Ice Water Concentrations in the 19 August 2015 Coastal Mesoconvective System

Science.gov (United States)

Proctor, Fred H.; Harrah, Steven; Switzer, George F.; Strickland, Justin K.; Hunt, Patricia J.

2017-01-01

During August 2015, NASA's DC-8 research aircraft was flown into High Ice Water Content (HIWC) events as part of a three-week campaign to collect airborne radar data and to obtain measurements from microphysical probes. Goals for this flight campaign included improved characterization of HIWC events, especially from an airborne radar perspective. This paper focuses on one of the flight days, in which a coastal mesoscale convective system (MCS) was investigated for HIWC conditions. The system appears to have been maintained by bands of convection flowing in from the Gulf of Mexico. These convective bands were capped by a large cloud canopy, which masks the underlying structure if viewed from an infrared sensing satellite. The DC-8 was equipped with an IsoKinetic Probe that measured ice concentrations of up to 2.3 g m(exp -3) within the cloud canopy of this system. Sustained measurements of ice crystals with concentrations exceeding 1 g m(exp -3) were encountered for up to ten minutes of flight time. Airborne Radar reflectivity factors were found to be weak within these regions of high ice water concentrations, suggesting that Radar detection of HIWC would be a challenging endeavor. This case is then investigated using a three-dimensional numerical cloud model. Profiles of ice water concentrations and radar reflectivity factor demonstrate similar magnitudes and scales between the flight measurements and model simulation. Also discussed are recent modifications to the numerical model's ice-microphysics that are based on measurements during the flight campaign. The numerical model and its updated ice-microphysics are further validated with a simulation of a well-known case of a supercell hailstorm measured during the Cooperative Convective Precipitation Experiment. Differences in HIWC between the continental supercell and the coastal MCS are discussed.

Synoptic Traveling Weather Systems on Mars: Effects of Radiatively-Active Water Ice Clouds

Science.gov (United States)

Hollingsworth, Jeffery; Kahre, Melinda; Haberle, Robert; Urata, Richard

2017-01-01

Atmospheric aerosols on Mars are critical in determining the nature of its thermal structure, its large-scale circulation, and hence the overall climate of the planet. We conduct multi-annual simulations with the latest version of the NASA Ames Mars global climate model (GCM), gcm2.3+, that includes a modernized radiative-transfer package and complex water-ice cloud microphysics package which permit radiative effects and interactions of suspended atmospheric aerosols (e.g., water ice clouds, water vapor, dust, and mutual interactions) to influence the net diabatic heating. Results indicate that radiatively active water ice clouds profoundly affect the seasonal and annual mean climate. The mean thermal structure and balanced circulation patterns are strongly modified near the surface and aloft. Warming of the subtropical atmosphere at altitude and cooling of the high latitude atmosphere at low levels takes place, which increases the mean pole-to-equator temperature contrast (i.e., "baroclinicity"). With radiatively active water ice clouds (RAC) compared to radiatively inert water ice clouds (nonRAC), significant changes in the intensity of the mean state and forced stationary Rossby modes occur, both of which affect the vigor and intensity of traveling, synoptic period weather systems.Such weather systems not only act as key agents in the transport of heat and momentum beyond the extent of the Hadley circulation, but also the transport of trace species such as water vapor, water ice-clouds, dust and others. The northern hemisphere (NH) forced Rossby waves and resultant wave train are augmented in the RAC case: the modes are more intense and the wave train is shifted equatorward. Significant changes also occur within the subtropics and tropics. The Rossby wave train sets up, combined with the traveling synoptic period weather systems (i.e., cyclones and anticyclones), the geographic extent of storm zones (or storm tracks) within the NH. A variety of circulation

Direct calculation of ice homogeneous nucleation rate for a molecular model of water

Science.gov (United States)

Haji-Akbari, Amir; Debenedetti, Pablo G.

2015-01-01

Ice formation is ubiquitous in nature, with important consequences in a variety of environments, including biological cells, soil, aircraft, transportation infrastructure, and atmospheric clouds. However, its intrinsic kinetics and microscopic mechanism are difficult to discern with current experiments. Molecular simulations of ice nucleation are also challenging, and direct rate calculations have only been performed for coarse-grained models of water. For molecular models, only indirect estimates have been obtained, e.g., by assuming the validity of classical nucleation theory. We use a path sampling approach to perform, to our knowledge, the first direct rate calculation of homogeneous nucleation of ice in a molecular model of water. We use TIP4P/Ice, the most accurate among existing molecular models for studying ice polymorphs. By using a novel topological approach to distinguish different polymorphs, we are able to identify a freezing mechanism that involves a competition between cubic and hexagonal ice in the early stages of nucleation. In this competition, the cubic polymorph takes over because the addition of new topological structural motifs consistent with cubic ice leads to the formation of more compact crystallites. This is not true for topological hexagonal motifs, which give rise to elongated crystallites that are not able to grow. This leads to transition states that are rich in cubic ice, and not the thermodynamically stable hexagonal polymorph. This mechanism provides a molecular explanation for the earlier experimental and computational observations of the preference for cubic ice in the literature. PMID:26240318

Up-going Red Water in the Ice at the Bottom of the World: Picture Taking Boxes and Listening Boxes Tell Us How and Why

Science.gov (United States)

Carr, C. G.; Pettit, E. C.

2017-12-01

Blood Falls is a place where red water comes out from under ice to the top of the ice and makes a strange red water fall. This ice is part of the big ice at the bottom of the world. The red water only comes out at some times and not every year, but it always comes out at the same place. The red water is important because it has tiny tiny not-animal life that tells us how life could be on other worlds. Knowing about the ice and red water is important because this ice is cold, colder than other ice in other places, and we want to know how water can get through. We didn't know why the red water comes up from under the ice when it does or how. We wanted to understand how the ice breaks and we watched the ice by taking pictures all year to see when the red water comes out. We found out that in the cold part of one year, the red water came out even though the air was not warm enough for water to be water! We think the red water comes out because the red water is blocked under the heavy ice and gets pushed tight. In the cold part of the year, cracks break down from the air into the ice and other cracks break up from under the ice because the red water is so pushed. The cracks from the top and bottom of the ice join, and the red water comes out. We used listening boxes that can feel how the ground moves to understand that the ice is breaking at the bottom and we can see that it breaks at the top of the ice. The red water can stay water and not ice inside the big ice because the red water has tiny pieces of the same stuff that can turn ice into water on the roads. If the ice breaks in the cold time, no water can get in from the top of the ice, so the red water under the ice stays clean from the air water. If the ice breaks in the warm time of year, water could get in from the top of the ice and make the red water under the ice not clean from the air. Since we saw in our pictures that the red water came out in the cold time of year, this means the red water could stay clean

Computational studies of atmospherically-relevant chemical reactions in water clusters and on liquid water and ice surfaces.

Science.gov (United States)

Gerber, R Benny; Varner, Mychel E; Hammerich, Audrey D; Riikonen, Sampsa; Murdachaew, Garold; Shemesh, Dorit; Finlayson-Pitts, Barbara J

2015-02-17

CONSPECTUS: Reactions on water and ice surfaces and in other aqueous media are ubiquitous in the atmosphere, but the microscopic mechanisms of most of these processes are as yet unknown. This Account examines recent progress in atomistic simulations of such reactions and the insights provided into mechanisms and interpretation of experiments. Illustrative examples are discussed. The main computational approaches employed are classical trajectory simulations using interaction potentials derived from quantum chemical methods. This comprises both ab initio molecular dynamics (AIMD) and semiempirical molecular dynamics (SEMD), the latter referring to semiempirical quantum chemical methods. Presented examples are as follows: (i) Reaction of the (NO(+))(NO3(-)) ion pair with a water cluster to produce the atmospherically important HONO and HNO3. The simulations show that a cluster with four water molecules describes the reaction. This provides a hydrogen-bonding network supporting the transition state. The reaction is triggered by thermal structural fluctuations, and ultrafast changes in atomic partial charges play a key role. This is an example where a reaction in a small cluster can provide a model for a corresponding bulk process. The results support the proposed mechanism for production of HONO by hydrolysis of NO2 (N2O4). (ii) The reactions of gaseous HCl with N2O4 and N2O5 on liquid water surfaces. Ionization of HCl at the water/air interface is followed by nucleophilic attack of Cl(-) on N2O4 or N2O5. Both reactions proceed by an SN2 mechanism. The products are ClNO and ClNO2, precursors of atmospheric atomic chlorine. Because this mechanism cannot result from a cluster too small for HCl ionization, an extended water film model was simulated. The results explain ClNO formation experiments. Predicted ClNO2 formation is less efficient. (iii) Ionization of acids at ice surfaces. No ionization is found on ideal crystalline surfaces, but the process is efficient on

High salinity tolerance in eggs and fry of a brackish Esox lucius population

DEFF Research Database (Denmark)

Jørgensen, A.T.; Hansen, B.W.; Vismann, B.

2010-01-01

Knowledge on the biology and physiology of pike, Esox lucius L., populations inhabiting saline environments is scarce. An experimental setup was used to examine egg development and fry behaviour and growth under varying salinity levels in a brackish-water pike population from the western Baltic Sea....... Eggs and fry developed at 8.5 psu, which is higher than hitherto reported for other populations. Fry exhibited stress behaviour and reduced growth when subjected to salinities above 13 psu. This indicates that early life stages of E. lucius tolerate ambient salinity conditions equivalent to the natural...

ADAPTIVE OPTICS OBSERVATIONS OF 3 {mu}m WATER ICE IN SILHOUETTE DISKS IN THE ORION NEBULA CLUSTER AND M43

Energy Technology Data Exchange (ETDEWEB)

Terada, Hiroshi; Pyo, Tae-Soo; Minowa, Yosuke; Hayano, Yutaka; Oya, Shin; Hattori, Masayuki; Takami, Hideki [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Tokunaga, Alan T. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Watanabe, Makoto [Department of Cosmosciences, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Saito, Yoshihiko [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan); Ito, Meguru [Department of Mechanical Engineering, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 5C2 (Canada); Iye, Masanori, E-mail: terada@subaru.naoj.org [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2012-12-01

We present the near-infrared images and spectra of four silhouette disks in the Orion Nebula Cluster (M42) and M43 using the Subaru Adaptive Optics system. While d053-717 and d141-1952 show no water ice feature at 3.1 {mu}m, a moderately deep ({tau}{sub ice} {approx} 0.7) water ice absorption is detected toward d132-1832 and d216-0939. Taking into account the water ice so far detected in the silhouette disks, the critical inclination angle to produce a water ice absorption feature is confirmed to be 65 Degree-Sign -75 Degree-Sign . As for d216-0939, the crystallized water ice profile is exactly the same as in the previous observations taken 3.63 years ago. If the water ice material is located at 30 AU, then the observations suggest it is uniform at a scale of about 3.5 AU.

Nonthermal ice nucleation observed at distorted contact lines of supercooled water drops.

Science.gov (United States)

Yang, Fan; Cruikshank, Owen; He, Weilue; Kostinski, Alex; Shaw, Raymond A

2018-02-01

Ice nucleation is the crucial step for ice formation in atmospheric clouds and therefore underlies climatologically relevant precipitation and radiative properties. Progress has been made in understanding the roles of temperature, supersaturation, and material properties, but an explanation for the efficient ice nucleation occurring when a particle contacts a supercooled water drop has been elusive for over half a century. Here, we explore ice nucleation initiated at constant temperature and observe that mechanical agitation induces freezing of supercooled water drops at distorted contact lines. Results show that symmetric motion of supercooled water on a vertically oscillating substrate does not freeze, no matter how we agitate it. However, when the moving contact line is distorted with the help of trace amounts of oil or inhomogeneous pinning on the substrate, freezing can occur at temperatures much higher than in a static droplet, equivalent to ∼10^{10} increase in nucleation rate. Several possible mechanisms are proposed to explain the observations. One plausible explanation among them, decreased pressure due to interface curvature, is explored theoretically and compared with the observational results quasiquantitatively. Indeed, the observed freezing-temperature increase scales with contact line speed in a manner consistent with the pressure hypothesis. Whatever the mechanism, the experiments demonstrate a strong preference for ice nucleation at three-phase contact lines compared to the two-phase interface, and they also show that movement and distortion of the contact line are necessary contributions to stimulating the nucleation process.

Sea Ice Ecosystems

Science.gov (United States)

Arrigo, Kevin R.

2014-01-01

Polar sea ice is one of the largest ecosystems on Earth. The liquid brine fraction of the ice matrix is home to a diverse array of organisms, ranging from tiny archaea to larger fish and invertebrates. These organisms can tolerate high brine salinity and low temperature but do best when conditions are milder. Thriving ice algal communities, generally dominated by diatoms, live at the ice/water interface and in recently flooded surface and interior layers, especially during spring, when temperatures begin to rise. Although protists dominate the sea ice biomass, heterotrophic bacteria are also abundant. The sea ice ecosystem provides food for a host of animals, with crustaceans being the most conspicuous. Uneaten organic matter from the ice sinks through the water column and feeds benthic ecosystems. As sea ice extent declines, ice algae likely contribute a shrinking fraction of the total amount of organic matter produced in polar waters.

Photochemistry of Coronene in Cosmic Water Ice Analogs at Different Concentrations

Science.gov (United States)

de Barros, A. L. F.; Mattioda, A. L.; Ricca, A.; Cruz-Diaz, G. A.; Allamandola, L. J.

2017-10-01

This work presents the photochemistry of ultraviolet (UV) irradiated coronene in water ices at 15 K studied using mid-infrared Fourier transform (FTIR) spectroscopy for C24H12:H2O at concentrations of (1:50), (1:150), (1:200), (1:300), and (1:400). Previous UV irradiation studies of anthracene:H2O, pyrene:H2O, and benzo[ghi]perylene:H2O ices at 15 K have shown that aromatic alcohols and ketones, as well as CO2 and H2CO, are formed at very low temperatures. Likewise, here, in addition to the coronene cation, hydroxy-, keto-, and protonated coronene (coronene H+) are formed. The rate constants for the decay of neutral coronene and for the formation of photoproducts have been derived. It is shown that Polycyclic Aromatic Hydrocarbons (PAHs) and their UV induced PAH:H2O photoproducts have mid-infrared spectroscopic signatures in the 5-8 μm region that can contribute to the interstellar ice components described by Boogert et al. as C1-C5. Our results suggest that oxygenated and hydrogenated PAHs could be in UV-irradiated regions of the interstellar medium where water-rich ices are important.

The study of fresh-water lake ice using multiplexed imaging radar

Science.gov (United States)

Leonard, Bryan M.; Larson, R.W.

1975-01-01

The study of ice in the upper Great Lakes, both from the operational and the scientific points of view, is receiving continued attention. Quantitative and qualitative field work is being conducted to provide the needed background for accurate interpretation of remotely sensed data. The data under discussion in this paper were obtained by a side-looking multiplexed airborne radar (SLAR) supplemented with ground-truth data.Because of its ability to penetrate adverse weather, radar is an especially important instrument for monitoring ice in the upper Great Lakes. It has previously been shown that imaging radars can provide maps of ice cover in these areas. However, questions concerning both the nature of the surfaces reflecting radar energy and the interpretation of the radar imagery continually arise.Our analysis of ice in Whitefish Bay (Lake Superior) indicates that the combination of the ice/water interlace and the ice/air interface is the major contributor to the radar backscatter as seen on the imagery At these frequencies the ice has a very low relative dielectric permittivity (types studied include newly formed black ice, pancake ice, and frozen and consolidated pack and brash ice.Although ice thickness cannot be measured directly from the received signals, it is suspected that by combining the information pertaining to radar backscatter with data on the meteorological and sea-state history of the area, together with some basic ground truth, better estimates of the ice thickness may be provided. In addition, certain ice features (e.g. ridges, ice-foot formation, areas of brash ice) may be identified with reasonable confidence. There is a continued need for additional ground work to verify the validity of imaging radars for these types of interpretations.

Calcium carbonate precipitation in the Cueva di Watapana on Bonaire, Netherlands Antilles

NARCIS (Netherlands)

Meer Mohr, van der C.G.

1978-01-01

Calcium carbonate precipitates as low Mg-calcite and aragonite in slightly brackish water in a cave in the Pleistocene Middle Terrace of southern Bonaire. The calcium carbonate precipitates at the atmosphere-water interface forming floating calcite scales (calcite ice). Aragonite crystals frequently

Subglacial Lake Vostok (Antarctica accretion ice contains a diverse set of sequences from aquatic, marine and sediment-inhabiting bacteria and eukarya.

Directory of Open Access Journals (Sweden)

Yury M Shtarkman

Full Text Available Lake Vostok, the 7(th largest (by volume and 4(th deepest lake on Earth, is covered by more than 3,700 m of ice, making it the largest subglacial lake known. The combination of cold, heat (from possible hydrothermal activity, pressure (from the overriding glacier, limited nutrients and complete darkness presents extreme challenges to life. Here, we report metagenomic/metatranscriptomic sequence analyses from four accretion ice sections from the Vostok 5G ice core. Two sections accreted in the vicinity of an embayment on the southwestern end of the lake, and the other two represented part of the southern main basin. We obtained 3,507 unique gene sequences from concentrates of 500 ml of 0.22 µm-filtered accretion ice meltwater. Taxonomic classifications (to genus and/or species were possible for 1,623 of the sequences. Species determinations in combination with mRNA gene sequence results allowed deduction of the metabolic pathways represented in the accretion ice and, by extension, in the lake. Approximately 94% of the sequences were from Bacteria and 6% were from Eukarya. Only two sequences were from Archaea. In general, the taxa were similar to organisms previously described from lakes, brackish water, marine environments, soil, glaciers, ice, lake sediments, deep-sea sediments, deep-sea thermal vents, animals and plants. Sequences from aerobic, anaerobic, psychrophilic, thermophilic, halophilic, alkaliphilic, acidophilic, desiccation-resistant, autotrophic and heterotrophic organisms were present, including a number from multicellular eukaryotes.

Observed vulnerability of Filchner-Ronne Ice Shelf to wind-driven inflow of warm deep water

Science.gov (United States)

Darelius, E.; Fer, I.; Nicholls, K. W.

2016-01-01

The average rate of melting at the base of the large Filchner-Ronne Ice Shelf in the southern Weddell Sea is currently low, but projected to increase dramatically within the next century. In a model study, melt rates increase as changing ice conditions cause a redirection of a coastal current, bringing warm water of open ocean origin through the Filchner Depression and into the Filchner Ice Shelf cavity. Here we present observations from near Filchner Ice Shelf and from the Filchner Depression, which show that pulses of warm water already arrive as far south as the ice front. This southward heat transport follows the eastern flank of the Filchner Depression and is found to be directly linked to the strength of a wind-driven coastal current. Our observations emphasize the potential sensitivity of Filchner-Ronne Ice Shelf melt rates to changes in wind forcing. PMID:27481659

Ice haze, snow, and the Mars water cycle

International Nuclear Information System (INIS)

Kahn, R.

1990-01-01

Images of the limb of Mars reveal discrete cloud layers between 20 and 80 km above the surface. They appear to be composed of water ice and have a number of characteristics similar to hazes that produce diamond dust precipitation in the continental Antarctic of Earth. Temperatures from 170 K to 190 K are deduced at the condensation levels. Eddy diffusion coefficients around 10 5 cm 2 s -1 , typical of a nonconvecting atmosphere, are also derived in the haze regions at times when the atmosphere is relatively clear of dust. This parameter apparently changes by more than 3 orders of magnitude with season and local conditions, with important implications for vertical transport of water and dust and for models of photochemistry and middle atmosphere dynamics. For the cases studied, particle sizes vary systematically by more than an order of magnitude with condensation level, in such a way that the characteristic fall time for particles is always about 1 Mars day, which is the dominant thermal forcing time. The hazes may play a key role in the seasonal water cycle of Mars. They provide a mechanism for growing particles large enough to move atmospheric water closer to the surface, thereby improving the efficiency of adsorption and ice deposit formation in the regolith. This is particularly likely in late northern summer, when the rapid hemispheric decrease in atmospheric water vapor may reflect the precipitation of snow. This rapid decrease in late summer involves atmospheric water vapor in about the quantities needed to supply the mid-latitude regolith with the water that appears in the atmosphere early in the following spring

The effects of sub-ice-shelf melting on dense shelf water formation and export in idealized simulations of Antarctic margins

Science.gov (United States)

Marques, Gustavo; Stern, Alon; Harrison, Matthew; Sergienko, Olga; Hallberg, Robert

2017-04-01

Dense shelf water (DSW) is formed in coastal polynyas around Antarctica as a result of intense cooling and brine rejection. A fraction of this water reaches ice shelves cavities and is modified due to interactions with sub-ice-shelf melt water. This modified water mass contributes to the formation of Antarctic Bottom Water, and consequently, influences the large-scale ocean circulation. Here, we investigate the role of sub-ice-shelf melting in the formation and export of DSW using idealized simulations with an isopycnal ocean model (MOM6) coupled with a sea ice model (SIS2) and a thermodynamic active ice shelf. A set of experiments is conducted with variable horizontal grid resolutions (0.5, 1.0 and 2.0 km), ice shelf geometries and atmospheric forcing. In all simulations DSW is spontaneously formed in coastal polynyas due to the combined effect of the imposed atmospheric forcing and the ocean state. Our results show that sub-ice-shelf melting can significantly change the rate of dense shelf water outflows, highlighting the importance of this process to correctly represent bottom water formation.

Successful water management for the oil sands industry

International Nuclear Information System (INIS)

Braun, B.

2003-01-01

Water is a key requirement to produce oil from thermal oil sands projects. Historically, water was considered as a renewable resource that could be used when necessary. Water use is currently examined in a wider context. Canadian Natural Resources Limited has used fresh water for thermal projects in the past, including its thermal operations at Primrose and Wolf Lake. However, technical advancements have made it possible to use recycled water. This allows companies to survive within their licenses while increasing production. Other advances include the use of brackish water, and innovations such as using depleted reservoir sections to store water to increase the use of recycled water. It was noted that brackish water resources need to be mapped and understood in greater detail. The objective is to use brackish water at a cost equal to, or less, than fresh water

Archival processes of the water stable isotope signal in East Antarctic ice cores

Science.gov (United States)

Casado, Mathieu; Landais, Amaelle; Picard, Ghislain; Münch, Thomas; Laepple, Thomas; Stenni, Barbara; Dreossi, Giuliano; Ekaykin, Alexey; Arnaud, Laurent; Genthon, Christophe; Touzeau, Alexandra; Masson-Delmotte, Valerie; Jouzel, Jean

2018-05-01

The oldest ice core records are obtained from the East Antarctic Plateau. Water isotopes are key proxies to reconstructing past climatic conditions over the ice sheet and at the evaporation source. The accuracy of climate reconstructions depends on knowledge of all processes affecting water vapour, precipitation and snow isotopic compositions. Fractionation processes are well understood and can be integrated in trajectory-based Rayleigh distillation and isotope-enabled climate models. However, a quantitative understanding of processes potentially altering snow isotopic composition after deposition is still missing. In low-accumulation sites, such as those found in East Antarctica, these poorly constrained processes are likely to play a significant role and limit the interpretability of an ice core's isotopic composition. By combining observations of isotopic composition in vapour, precipitation, surface snow and buried snow from Dome C, a deep ice core site on the East Antarctic Plateau, we found indications of a seasonal impact of metamorphism on the surface snow isotopic signal when compared to the initial precipitation. Particularly in summer, exchanges of water molecules between vapour and snow are driven by the diurnal sublimation-condensation cycles. Overall, we observe in between precipitation events modification of the surface snow isotopic composition. Using high-resolution water isotopic composition profiles from snow pits at five Antarctic sites with different accumulation rates, we identified common patterns which cannot be attributed to the seasonal variability of precipitation. These differences in the precipitation, surface snow and buried snow isotopic composition provide evidence of post-deposition processes affecting ice core records in low-accumulation areas.

Hybrid male sterility between the fresh- and brackish-water types of ninespine stickleback Pungitius pungitius (Pisces, Gasterosteidae).

Science.gov (United States)

Takahashi, Hiroshi; Nagai, Terumi; Goto, Akira

2005-01-01

Two ecologically distinct forms, fresh- and brackish-water types, of ninespine stickleback co-exist in several freshwater systems on the coast of eastern Hokkaido. Recent genetic analyses of 13 allozyme loci revealed genetic separation between the two types even though their spawning grounds were in close proximity. On the other hand, there is only a small difference in mitochondrial DNA (mtDNA) sequence between the two types suggesting that they diverged quite recently or that mtDNA introgression occurred between them. To test for postzygotic reproductive isolating mechanisms and hybrid mediated gene flow, we examined the viability and reproductive performance of reciprocal F1 hybrids. The hybrids grew to the adult size normally and both sexes expressed secondary sexual characters in the reciprocal crosses. The female hybrids were reciprocally fertile, while the male hybrids were reciprocally sterile. Histological and flow-cytometric analyses of the hybrid testis revealed that the sterility pattern was classified as 'gametic sterility,' with gonads of normal size but abnormal spermatogenesis. To our knowledge, the present finding is a novel example of one sex hybrid sterility in the stickleback family (Gasterosteidae).

Surfacing behavior and gas release of the physostome sprat (Sprattus sprattus) in ice-free and ice-covered waters

KAUST Repository

Solberg, Ingrid

2013-10-04

Upward-facing echosounders that provided continuous, long-term measurements were applied to address the surfacing behavior and gas release of the physostome sprat (Sprattus sprattus) throughout an entire winter in a 150-m-deep Norwegian fjord. During ice-free conditions, the sprat surfaced and released gas bubbles at night with an estimated surfacing rate of 3.5 times per fish day-1. The vertical swimming speeds during surfacing were considerably higher (~10 times) than during diel vertical migrations, especially when returning from the surface, and particularly when the fjord was not ice covered. The sprat released gas a few hours after surfacing, suggesting that the sprat gulped atmospheric air during its excursions to the surface. While the surface activity increased after the fjord became ice covered, the records of gas release decreased sharply. The under-ice fish then displayed a behavior interpreted as "searching for the surface" by repeatedly ascending toward the ice, apparently with limited success of filling the swim bladder. This interpretation was supported by lower acoustic target strength in ice-covered waters. The frequent surfacing behavior demonstrated in this study indicates that gulping of atmospheric air is an important element in the life of sprat. While at least part of the population endured overwintering in the ice-covered habitat, ice covering may constrain those physostome fishes that lack a gas-generating gland in ways that remain to be established. 2013 The Author(s).

Increased Ice-age Influence of Antarctic Intermediate Water.

Science.gov (United States)

Muratli, J.; McManus, J.; Mix, A.; Chase, Z.

2008-12-01

A depth transect of three ODP sites collected along the central Chile Margin constrain Antarctic Intermediate Water (AAIW) distributions and regional export production over the last 30 ka. Reduced Re and Cd, and increased Mn are proxies for higher bottom water oxygenation; 230Th-normalized burial of opal is a proxy for productivity. Mn/Al is high during the glacial interval at all three sites, suggesting high oxygenation and the retreat of the oxygen minimum zone during this period. At Site 1233, within the core of modern AAIW, Re and Cd are unchanged from detrital values throughout the last 30 ky, implying continuously oxic conditions. In contrast, at the northern sites 1234 and 1235, which reside below and above AAIW respectively, Re and Cd rise rapidly from low glacial values at ~15ka, signifying lower oxygen concentrations at the sea floor during Holocene time relative to ice-age conditions. Local productivity, recorded in Th-normalized opal burial, is highest during the glacial interval at both sites 1233 and 1234, and varies independently from the redox proxies. We conclude that local productivity does not drive bottom water oxygenation here, and that ventilation of the shallow subsurface southeast Pacific increased during the last ice age, with an expanded depth range of AAIW relative to the present.

Identification of Accretion as Grain Growth Mechanism in Astrophysically Relevant Water&ice Dusty Plasma Experiment

Science.gov (United States)

Marshall, Ryan S.; Chai, Kil-Byoung; Bellan, Paul M.

2017-03-01

The grain growth process in the Caltech water-ice dusty plasma experiment has been studied using a high-speed camera and a long-distance microscope lens. It is observed that (I) the ice grain number density decreases fourfold as the average grain major axis increases from 20 to 80 μm, (II) the major axis length has a log-normal distribution rather than a power-law dependence, and (III) no collisions between ice grains are apparent. The grains have a large negative charge resulting in strong mutual repulsion and this, combined with the fractal character of the ice grains, prevents them from agglomerating. In order for the grain kinetic energy to be sufficiently small to prevent collisions between ice grains, the volumetric packing factor (I.e., ratio of the actual volume to the volume of a circumscribing ellipsoid) of the ice grains must be less than ˜0.1 depending on the exact relative velocity of the grains in question. Thus, it is concluded that direct accretion of water molecules is very likely to dominate the observed ice grain growth.

The Effect of Seasonal Variability of Atlantic Water on the Arctic Sea Ice Cover

Science.gov (United States)

Ivanov, V. V.; Repina, I. A.

2018-01-01

Under the influence of global warming, the sea ice in the Arctic Ocean (AO) is expected to reduce with a transition toward a seasonal ice cover by the end of this century. A comparison of climate-model predictions with measurements shows that the actual rate of ice cover decay in the AO is higher than the predicted one. This paper argues that the rapid shrinking of the Arctic summer ice cover is due to its increased seasonality, while seasonal oscillations of the Atlantic origin water temperature create favorable conditions for the formation of negative anomalies in the ice-cover area in winter. The basis for this hypothesis is the fundamental possibility of the activation of positive feedback provided by a specific feature of the seasonal cycle of the inflowing Atlantic origin water and the peaking of temperature in the Nansen Basin in midwinter. The recently accelerated reduction in the summer ice cover in the AO leads to an increased accumulation of heat in the upper ocean layer during the summer season. The extra heat content of the upper ocean layer favors prerequisite conditions for winter thermohaline convection and the transfer of heat from the Atlantic water (AW) layer to the ice cover. This, in turn, contributes to further ice thinning and a decrease in ice concentration, accelerated melting in summer, and a greater accumulation of heat in the ocean by the end of the following summer. An important role is played by the seasonal variability of the temperature of AW, which forms on the border between the North European and Arctic basins. The phase of seasonal oscillation changes while the AW is moving through the Nansen Basin. As a result, the timing of temperature peak shifts from summer to winter, additionally contributing to enhanced ice melting in winter. The formulated theoretical concept is substantiated by a simplified mathematical model and comparison with observations.

Bibliography of Ice Properties and Forecasting Related to Transportation in Ice-Covered Waters.

Science.gov (United States)

1980-09-01

N. and Tabata , T., Ice study in the Gulf of Peschanskii, I.S., Ice science and ice technology, Bothnia, III: observations on large grains of ice...ice and by Sterrett, K.F., The arctic environment and the hitting ice floes. Results of these measurements have arctic surface effect vehicle, Cold...ice growth, temperature 26-3673 effects, ice cover thickness. 28-557 Determining contact stresses when a ship’s stem hits the ice, Kheisin, D.E

Photochemistry of Coronene in Cosmic Water Ice Analogs at Different Concentrations

Energy Technology Data Exchange (ETDEWEB)

De Barros, A. L. F. [Departamento de Física, Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Av. Maracanã 229, 20271-110 Rio de Janeiro, RJ (Brazil); Mattioda, A. L.; Ricca, A.; Cruz-Diaz, G.A.; Allamandola, L. J. [NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035-1000 (United States)

2017-10-20

This work presents the photochemistry of ultraviolet (UV) irradiated coronene in water ices at 15 K studied using mid-infrared Fourier transform (FTIR) spectroscopy for C{sub 24}H{sub 12}:H{sub 2}O at concentrations of (1:50), (1:150), (1:200), (1:300), and (1:400). Previous UV irradiation studies of anthracene:H{sub 2}O, pyrene:H{sub 2}O, and benzo[ghi]perylene:H{sub 2}O ices at 15 K have shown that aromatic alcohols and ketones, as well as CO{sub 2} and H{sub 2}CO, are formed at very low temperatures. Likewise, here, in addition to the coronene cation, hydroxy-, keto-, and protonated coronene (coronene H{sup +}) are formed. The rate constants for the decay of neutral coronene and for the formation of photoproducts have been derived. It is shown that Polycyclic Aromatic Hydrocarbons (PAHs) and their UV induced PAH:H{sub 2}O photoproducts have mid-infrared spectroscopic signatures in the 5–8 μ m region that can contribute to the interstellar ice components described by Boogert et al. as C1–C5. Our results suggest that oxygenated and hydrogenated PAHs could be in UV-irradiated regions of the interstellar medium where water-rich ices are important.

Photochemistry of Coronene in Cosmic Water Ice Analogs at Different Concentrations

International Nuclear Information System (INIS)

De Barros, A. L. F.; Mattioda, A. L.; Ricca, A.; Cruz-Diaz, G.A.; Allamandola, L. J.

2017-01-01

This work presents the photochemistry of ultraviolet (UV) irradiated coronene in water ices at 15 K studied using mid-infrared Fourier transform (FTIR) spectroscopy for C 24 H 12 :H 2 O at concentrations of (1:50), (1:150), (1:200), (1:300), and (1:400). Previous UV irradiation studies of anthracene:H 2 O, pyrene:H 2 O, and benzo[ghi]perylene:H 2 O ices at 15 K have shown that aromatic alcohols and ketones, as well as CO 2 and H 2 CO, are formed at very low temperatures. Likewise, here, in addition to the coronene cation, hydroxy-, keto-, and protonated coronene (coronene H + ) are formed. The rate constants for the decay of neutral coronene and for the formation of photoproducts have been derived. It is shown that Polycyclic Aromatic Hydrocarbons (PAHs) and their UV induced PAH:H 2 O photoproducts have mid-infrared spectroscopic signatures in the 5–8 μ m region that can contribute to the interstellar ice components described by Boogert et al. as C1–C5. Our results suggest that oxygenated and hydrogenated PAHs could be in UV-irradiated regions of the interstellar medium where water-rich ices are important.

Multipole moments of water molecules in clusters and ice Ih from first principles calculations

International Nuclear Information System (INIS)

Batista, E.R.; Xantheas, S.S.; Jonsson, H.

1999-01-01

We have calculated molecular multipole moments for water molecules in clusters and in ice Ih by partitioning the charge density obtained from first principles calculations. Various schemes for dividing the electronic charge density among the water molecules were used. They include Bader close-quote s zero flux surfaces and Voronoi partitioning schemes. A comparison was also made with an induction model including dipole, dipole-quadrupole, quadrupole-quadrupole polarizability and first hyperpolarizability as well as fixed octopole and hexadecapole moments. We have found that the different density partitioning schemes lead to widely different values for the molecular multipoles, illustrating how poorly defined molecular multipoles are in clusters and condensed environments. For instance, the magnitude of the molecular dipole moment in ice Ih ranges between 2.3 D and 3.1 D depending on the partitioning scheme used. Within each scheme, though, the value for the molecular dipole moment in ice is larger than in the hexamer. The magnitude of the molecular dipole moment in the clusters shows a monotonic increase from the gas phase value to the one in ice Ih, with the molecular dipole moment in the water ring hexamer being smaller than the one in ice Ih for all the partitioning schemes used. copyright 1999 American Institute of Physics

On the Formation of Interstellar Water Ice: Constraints from a Search for Hydrogen Peroxide Ice in Molecular Clouds

Science.gov (United States)

Smith, R. G.; Charnely, S. B.; Pendleton, Y. J.; Wright, C. M.; Maldoni, M. M.; Robinson, G.

2011-01-01

Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H2O2), for the production of water (H2O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H2O2 ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H2O2 should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H2O2/H2O ice films between 2.5 and 200 micron, from 10 to 180 K, containing 3%, 30%, and 97% H2O2 ice. Integrated absorbances for all the absorption features in low-temperature H2O2 ice have been derived from these spectra. For identifying H2O2 ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3 micron. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H2O ice absorption bands, no absorption features are found that can definitely be identified with H2O2 ice. In the absence of definite H2O2 features, the H2O2 abundance is constrained by its possible contribution to the weak absorption feature near 3.47 micron found on the long-wavelength wing of the 3 micron H2O ice band. This gives an average upper limit for H2O2, as a percentage of H2O, of 9% +/- 4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.

Methane excess in Arctic surface water-triggered by sea ice formation and melting.

Science.gov (United States)

Damm, E; Rudels, B; Schauer, U; Mau, S; Dieckmann, G

2015-11-10

Arctic amplification of global warming has led to increased summer sea ice retreat, which influences gas exchange between the Arctic Ocean and the atmosphere where sea ice previously acted as a physical barrier. Indeed, recently observed enhanced atmospheric methane concentrations in Arctic regions with fractional sea-ice cover point to unexpected feedbacks in cycling of methane. We report on methane excess in sea ice-influenced water masses in the interior Arctic Ocean and provide evidence that sea ice is a potential source. We show that methane release from sea ice into the ocean occurs via brine drainage during freezing and melting i.e. in winter and spring. In summer under a fractional sea ice cover, reduced turbulence restricts gas transfer, then seawater acts as buffer in which methane remains entrained. However, in autumn and winter surface convection initiates pronounced efflux of methane from the ice covered ocean to the atmosphere. Our results demonstrate that sea ice-sourced methane cycles seasonally between sea ice, sea-ice-influenced seawater and the atmosphere, while the deeper ocean remains decoupled. Freshening due to summer sea ice retreat will enhance this decoupling, which restricts the capacity of the deeper Arctic Ocean to act as a sink for this greenhouse gas.

Viscous organic aerosol particles in the upper troposphere: diffusivity-controlled water uptake and ice nucleation?

Directory of Open Access Journals (Sweden)

D. M. Lienhard

2015-12-01

secondary organic aerosol (SOA material produced by oxidation of α-pinene and in a number of organic/inorganic model mixtures (3-methylbutane-1,2,3-tricarboxylic acid (3-MBTCA, levoglucosan, levoglucosan/NH4HSO4, raffinose are presented. These indicate that water diffusion coefficients are determined by several properties of the aerosol substance and cannot be inferred from the glass transition temperature or bouncing properties. Our results suggest that water diffusion in SOA particles is faster than often assumed and imposes no significant kinetic limitation on water uptake and release at temperatures above 220 K. The fast diffusion of water suggests that heterogeneous ice nucleation on a glassy core is very unlikely in these systems. At temperatures below 220 K, model simulations of SOA particles suggest that heterogeneous ice nucleation may occur in the immersion mode on glassy cores which remain embedded in a liquid shell when experiencing fast updraft velocities. The particles absorb significant quantities of water during these updrafts which plasticize their outer layers such that these layers equilibrate readily with the gas phase humidity before the homogeneous ice nucleation threshold is reached. Glass formation is thus unlikely to restrict homogeneous ice nucleation. Only under most extreme conditions near the very high tropical tropopause may the homogeneous ice nucleation rate coefficient be reduced as a consequence of slow condensed-phase water diffusion. Since the differences between the behavior limited or non limited by diffusion are small even at the very high tropical tropopause, condensed-phase water diffusivity is unlikely to have significant consequences on the direct climatic effects of SOA particles under tropospheric conditions.

Analysis of the Effect of Water Activity on Ice Formation Using a New Theory of Nucleation

Science.gov (United States)

Barahona, Donifan

2013-01-01

In this work a new theory of nucleation is developed and used to investigate the effect of water activity on the formation of ice within super-cooled droplets. The new theory is based on a novel concept where the interface is assumed to be made of liquid molecules trapped by the solid matrix. Using this concept new expressions are developed for the critical ice germ size and the nucleation work, with explicit dependencies on temperature and water activity. However unlike previous approaches, the new theory does not depend on the interfacial tension between liquid and ice. Comparison against experimental results shows that the new theory is able to reproduce the observed effect of water activity on nucleation rate and freezing temperature. It allows for the first time a theoretical derivation of the constant shift in water activity between melting and nucleation. The new theory offers a consistent thermodynamic view of ice nucleation, simple enough to be applied in atmospheric models of cloud formation.

New measurements on water ice photodesorption and product formation under ultraviolet irradiation

Science.gov (United States)

Cruz-Diaz, Gustavo A.; Martín-Doménech, Rafael; Moreno, Elena; Muñoz Caro, Guillermo M.; Chen, Yu-Jung

2018-03-01

The photodesorption of icy grain mantles has been claimed to be responsible for the abundance of gas-phase molecules towards cold regions. Being water a ubiquitous molecule, it is crucial to understand its role in photochemistry and its behaviour under an ultraviolet field. We report new measurements on the ultraviolet (UV) photodesorption of water ice and its H2, OH, and O2 photoproducts using a calibrated quadrupole mass spectrometer. Solid water was deposited under ultra-high-vacuum conditions and then UV-irradiated at various temperatures starting from 8 K with a microwave discharged hydrogen lamp. Deuterated water was used for confirmation of the results. We found a photodesorption yield of 1.3 × 10-3 molecules per incident photon for water and 0.7 × 10-3 molecules per incident photon for deuterated water at the lowest irradiation temperature, 8 K. The photodesorption yield per absorbed photon is given and comparison with astrophysical scenarios, where water ice photodesorption could account for the presence of gas-phase water towards cold regions in the absence of a thermal desorption process, is addressed.

Metal-ion catalyzed polymerization in the eutectic phase in water-ice

DEFF Research Database (Denmark)

Monnard, Pierre-Alain; Szostak, Jack W.

2008-01-01

The emergence of an RNA world requires among other processes the non-enzymatic, template-directed replication of genetic polymers such as RNA or related nucleic acids, possibly catalyzed by metal ions. The absence of uridilate derivative polymerization on adenine containing templates has been...... the main issue preventing an efficient template-directed RNA polymerization. We report here the investigation of template-directed RNA polymerization in the eutectic phase in water-ice. In particular, it was found that activated Uridilate monomers in the presence of metal-ion catalysts could efficiently......-pairing opportunities. These results suggest that a template-directed RNA polymerization catalyzed by metal-ions could be carried out under eutectic phase in water-ice conditions....

Relevance and diversity of Nitrospira populations in biofilters of brackish RAS.

Directory of Open Access Journals (Sweden)

Myriam Kruse

Full Text Available Lithoautotrophic nitrite-oxidizing bacterial populations from moving-bed biofilters of brackish recirculation aquaculture systems (RAS; shrimp and barramundi were tested for their metabolic activity and phylogenetic diversity. Samples from the biofilters were labeled with (13C-bicarbonate and supplemented with nitrite at concentrations of 0.3, 3 and 10 mM, and incubated at 17 and 28°C, respectively. The biofilm material was analyzed by fatty acid methyl ester - stable isotope probing (FAME-SIP. High portions of up to 45% of Nitrospira-related labeled lipid markers were found confirming that Nitrospira is the major autotrophic nitrite oxidizer in these brackish systems with high nitrogen loads. Other nitrite-oxidizing bacteria such as Nitrobacter or Nitrotoga were functionally not relevant in the investigated biofilters. Nitrospira-related 16S rRNA gene sequences were obtained from the samples with 10 mM nitrite and analyzed by a cloning approach. Sequence studies revealed four different phylogenetic clusters within the marine sublineage IV of Nitrospira, though most sequences clustered with the type strain of Nitrospira marina and with a strain isolated from a marine RAS. Three lipids dominated the whole fatty acid profiles of nitrite-oxidizing marine and brackish enrichments of Nitrospira sublineage IV organisms. The membranes included two marker lipids (16∶1 cis7 and 16∶1 cis11 combined with the non-specific acid 16∶0 as major compounds and confirmed these marker lipids as characteristic for sublineage IV species. The predominant labeling of these characteristic fatty acids and the phylogenetic sequence analyses of the marine Nitrospira sublineage IV identified organisms of this sublineage as main autotrophic nitrite-oxidizers in the investigated brackish biofilter systems.

Hydroelectric power development and the ice regime of inland waters: A northern community perspective

International Nuclear Information System (INIS)

Gerard, R.

1989-03-01

Inland waters play a vital role in the life of the many small northern communities which depend in large measure on the provisions of the natural environment for their sustenance. These communities are therefore particularly vulnerable to changes in the ice regime of these waters, especially changes that are irregular. However, the north is also the site of much of Canada's hydroelectric power development and potential, developments that have a major influence on the ice regime of effected waters. As a contribution to the background information required for the necessary discussions and negotiations associated with such developments, the various aspects of the natural ice regime, the possible effects of hydroelectric development and operation on this regime, and its consequences, are briefly reviewed. The emphasis has been placed on changes that will likely be of most significance to northern communities in the bedrock-controlled country of the western Canadian Shield. The major direct, and in some circumstances life-threatening, impact of changes to the ice regime is on trafficability of the iceways that play such a vital role in the life of the communities. Hence particular emphasis has been placed on this aspect and on the formation of the slush and thin ice conditions that are the bane of over-ice travel and that are subject to unexpected changes by hydroelectric development and operation. To place these changes and their effects in some perspective, the nature of a hydroelectric development is also briefly described and an effort made to indicate the large costs incurred if these developments are restrained in their operation to avoid or mitigate some of the effects on the ice regime. 31 refs., 57 figs., 1 tab

The minimal ice water caloric test compared with established vestibular caloric test procedures.

Science.gov (United States)

Schmäl, Frank; Lübben, Björn; Weiberg, Kerstin; Stoll, Wolfgang

2005-01-01

Caloric testing of the vestibular labyrinth is usually performed by classical caloric test procedures (CCTP) using water warmed to 30 degrees C and 44 degrees C. Ice water irrigation (4 degrees C) is usually not performed, although it might be useful as a bedside test. To verify the validity of the Minimal Ice Water Caloric Test (MIWCT), comparative video-oculographic investigations were performed in 22 healthy subjects using ice water (0.5 ml, 1.0 ml, 2 ml), CCTP, and cold air (27 degrees C). Frequency, amplitude, slow phase velocity (SPV), the onset, and the duration of nystagmus were documented. After addition of three ice cubes, the temperature of conventional tap water (16 degrees C) fell within 13 min to 4 degrees C. In pessimum position the subjects demonstrated no nystagmus response. Compared to CCTP, MIWCT was associated with a significantly later onset of nystagmus and a significant prolongation of the nystagmus reaction. In contrast to air stimulation (27 degrees C), a significant Spearman's correlation was noted between MIWCT (1 and 2 ml) and established CCTP in respect of essential nystagmus parameters (frequency, amplitude and SPV). Furthermore, MIWCT (0.5 and 1 ml) showed a higher sensitivity and specificity with regard to the detection of canal paresis based on Jongkees' formula compared to stimulation with air 27 degrees C. Thus, MIWCT appears to be a suitable procedure for bedside investigation of vestibular function outside the vestibular laboratory, e.g. in a hospital ward, where bedridden patients with vertigo occasionally require vestibular testing.

Optimal Electromagnetic (EM) Geophysical Techniques to Map the Concentration of Subsurface Ice and Adsorbed Water on Mars and the Moon

Science.gov (United States)

Stillman, D. E.; Grimm, R. E.

2013-12-01

Water ice is ubiquitous in our Solar System and is a probable target for planetary exploration. Mapping the lateral and vertical concentration of subsurface ice from or near the surface could determine the origin of lunar and martian ice and quantify a much-needed resource for human exploration. Determining subsurface ice concentration on Earth is not trivial and has been attempted previously with electrical resistivity tomography (ERT), ground penetrating radar (GPR), airborne EM (AEM), and nuclear magnetic resonance (NMR). These EM geophysical techniques do not actually detect ice, but rather the absence of unfrozen water. This causes a non-unique interpretation of frozen and dry subsurface sediments. This works well in the arctic because most locations are not dry. However, for planetary exploration, liquid water is exceedingly rare and subsurface mapping must discriminate between an ice-rich and a dry subsurface. Luckily, nature has provided a unique electrical signature of ice: its dielectric relaxation. The dielectric relaxation of ice creates a temperature and frequency dependence of the electrical properties and varies the relative dielectric permittivity from ~3.1 at radar frequencies to >100 at low frequencies. On Mars, sediments smaller than silt size can hold enough adsorbed unfrozen water to complicate the measurement. This is because the presence of absorbed water also creates frequency-dependent electrical properties. The dielectric relaxation of adsorbed water and ice can be separated as they have different shapes and frequency ranges as long as a spectrum spanning the two relaxations is measured. The volume concentration of ice and adsorbed water is a function of the strength of their relaxations. Therefore, we suggest that capacitively-coupled dielectric spectroscopy (a.k.a. spectral induced polarization or complex resistivity) can detect the concentration of both ice and adsorbed water in the subsurface. To prove this concept we have collected

Comparison of carbon monoxide levels during heating of ice and water to boiling point with a camping stove.

Science.gov (United States)

Leigh-Smith, Simon; Watt, Ian; McFadyen, Angus; Grant, Stan

2004-01-01

To determine whether using a camping stove to bring a pan of ice to boiling point produces higher carbon monoxide (CO) concentration than would bringing a pan of water to boiling point. The hypothesis was that ice would cause greater CO concentration because of its greater flame-cooling effect and, consequently, more incomplete combustion. This was a randomized, prospective observational study. After an initial pilot study, CO concentration was monitored during 10 trials for each of ice and water. A partially ventilated 200-L cardboard box model was developed and then used inside a chamber at -6 degrees C. Ice temperature and volume, water temperature and volume, pan size, and flame characteristics were all standardized. Temperature of the heated medium was monitored to determine time to boiling point. Carbon monoxide concentration was monitored every 30 seconds for the first 3 minutes, then every minute until the end of each 10-minute trial. There was no significant difference (P > .05) in CO production levels between ice and water. Each achieved a similar mean plateau level of approximately 400 ppm CO concentration with a similar rate of rise. However, significantly higher (P = .014) CO concentration occurred at 4 and 5 minutes when the flame underwent a yellow flare; this occurred only on 3 occasions when ice was the medium. There were no significant differences for CO production between bringing a pan of ice or water to boiling point. In a small number of ice trials, the presence of a yellow flame resulted in high CO concentration. Yellow flares might occur more often with ice or snow melting, but this has not been proven.

ICE911 Research: Floating Safe Inert Materials to Preserve Ice and Conserve Water in Order to Mitigate Climate Change Impacts

Science.gov (United States)

Field, L. A.; Manzara, A.; Chetty, S.; Venkatesh, S.; Scholtz, A.

2015-12-01

Ice911 Research has conducted years of field testing to develop and test localized reversible engineering techniques to mitigate the negative impacts of polar ice melt. The technology uses environmentally safe materials to reflect energy in carefully selected, limited areas from summertime polar sun. The technology is now being adapted to help with California's drought. We have tested the albedo modification technique on a small scale over seven Winter/Spring seasons at sites including California's Sierra Nevada Mountains, a Canadian lake, and a small artificial pond in Minnesota about 100 ft in diameter and 6 ft deep at the center, using various materials and an evolving array of instrumentation. On the pond in Minnesota, this year's test results for ice preservation, using hollow glass spheres deployed over our largest test areas yet, showed that glass bubbles can provide an effective material for increasing albedo, significantly reducing the melting rate of ice. This year Ice911 also undertook its first small Arctic field test in Barrow, Alaska on a lake in Barrow's BEO area, and results are still coming in. The technology that Ice911 has been developing for ice preservation has also been shown to keep small test areas of water cooler, in various small-scale tests spanning years. We believe that with some adaptations of the technology, the materials can be applied to reservoirs and lakes to help stretch these precious resources further in California's ongoing drought. There are several distinct advantages for this method over alternatives such as large reverse osmosis projects or building new reservoirs, which could possibly allow a drought-stricken state to build fewer of these more-costly alternatives. First, applying an ecologically benign surface treatment of Ice911's materials can be accomplished within a season, at a lower cost, with far less secondary environmental impact, than such capital-and-time-intensive infrastructure projects. Second, keeping

Simultaneous measurement of unfrozen water content and ice content in frozen soil using gamma ray attenuation and TDR

Science.gov (United States)

Zhou, Xiaohai; Zhou, Jian; Kinzelbach, Wolfgang; Stauffer, Fritz

2014-12-01

The freezing temperature of water in soil is not constant but varies over a range determined by soil texture. Consequently, the amounts of unfrozen water and ice change with temperature in frozen soil, which in turn affects hydraulic, thermal, and mechanical properties of frozen soil. In this paper, an Am-241 gamma ray source and time-domain reflectometry (TDR) were combined to measure unfrozen water content and ice content in frozen soil simultaneously. The gamma ray attenuation was used to determine total water content. The TDR was used to determine the dielectric constant of the frozen soil. Based on a four-phase mixing model, the amount of unfrozen water content in the frozen soil could be determined. The ice content was inferred by the difference between total water content and unfrozen water content. The gamma ray attenuation and the TDR were both calibrated by a gravimetric method. Water contents measured by gamma ray attenuation and TDR in an unfrozen silt column under infiltration were compared and showed that the two methods have the same accuracy and response to changes of water content. Unidirectional column freezing experiments were performed to apply the combined method of gamma ray attenuation and TDR for measuring unfrozen water content and ice content. The measurement error of the gamma ray attenuation and TDR was around 0.02 and 0.01 m3/m3, respectively. The overestimation of unfrozen water in frozen soil by TDR alone was quantified and found to depend on the amount of ice content. The higher the ice content, the larger the overestimation. The study confirmed that the combined method could accurately determine unfrozen water content and ice content in frozen soil. The results of soil column freezing experiments indicate that total water content distribution is affected by available pore space and the freezing front advance rate. It was found that there is similarity between the soil water characteristic and the soil freezing characteristic of

Understanding Ice Shelf Basal Melting Using Convergent ICEPOD Data Sets: ROSETTA-Ice Study of Ross Ice Shelf

Science.gov (United States)

Bell, R. E.; Frearson, N.; Tinto, K. J.; Das, I.; Fricker, H. A.; Siddoway, C. S.; Padman, L.

2017-12-01

The future stability of the ice shelves surrounding Antarctica will be susceptible to increases in both surface and basal melt as the atmosphere and ocean warm. The ROSETTA-Ice program is targeted at using the ICEPOD airborne technology to produce new constraints on Ross Ice Shelf, the underlying ocean, bathymetry, and geologic setting, using radar sounding, gravimetry and laser altimetry. This convergent approach to studying the ice-shelf and basal processes enables us to develop an understanding of the fundamental controls on ice-shelf evolution. This work leverages the stratigraphy of the ice shelf, which is detected as individual reflectors by the shallow-ice radar and is often associated with surface scour, form close to the grounding line or pinning points on the ice shelf. Surface accumulation on the ice shelf buries these reflectors as the ice flows towards the calving front. This distinctive stratigraphy can be traced across the ice shelf for the major East Antarctic outlet glaciers and West Antarctic ice streams. Changes in the ice thickness below these reflectors are a result of strain and basal melting and freezing. Correcting the estimated thickness changes for strain using RIGGS strain measurements, we can develop decadal-resolution flowline distributions of basal melt. Close to East Antarctica elevated melt-rates (>1 m/yr) are found 60-100 km from the calving front. On the West Antarctic side high melt rates primarily develop within 10 km of the calving front. The East Antarctic side of Ross Ice Shelf is dominated by melt driven by saline water masses that develop in Ross Sea polynyas, while the melting on the West Antarctic side next to Hayes Bank is associated with modified Continental Deep Water transported along the continental shelf. The two sides of Ross Ice Shelf experience differing basal melt in part due to the duality in the underlying geologic structure: the East Antarctic side consists of relatively dense crust, with low amplitude

Minimum energy requirements for desalination of brackish groundwater in the United States with comparison to international datasets

Science.gov (United States)

Ahdab, Yvana D.; Thiel, Gregory P.; Böhlke, John Karl; Stanton, Jennifer S.; Lienhard, John H.

2018-01-01

This paper uses chemical and physical data from a large 2017 U.S. Geological Surveygroundwater dataset with wells in the U.S. and three smaller international groundwater datasets with wells primarily in Australia and Spain to carry out a comprehensive investigation of brackish groundwater composition in relation to minimum desalinationenergy costs. First, we compute the site-specific least work required for groundwater desalination. Least work of separation represents a baseline for specific energy consumptionof desalination systems. We develop simplified equations based on the U.S. data for least work as a function of water recovery ratio and a proxy variable for composition, either total dissolved solids, specific conductance, molality or ionic strength. We show that the U.S. correlations for total dissolved solids and molality may be applied to the international datasets. We find that total molality can be used to calculate the least work of dilute solutions with very high accuracy. Then, we examine the effects of groundwater solute composition on minimum energy requirements, showing that separation requirements increase from calcium to sodium for cations and from sulfate to bicarbonate to chloride for anions, for any given TDS concentration. We study the geographic distribution of least work, total dissolved solids, and major ions concentration across the U.S. We determine areas with both low least work and high water stress in order to highlight regions holding potential for desalination to decrease the disparity between high water demand and low water supply. Finally, we discuss the implications of the USGS results on water resource planning, by comparing least work to the specific energy consumption of brackish water reverse osmosisplants and showing the scaling propensity of major electrolytes and silica in the U.S. groundwater samples.

Homogeneous ice nucleation from aqueous inorganic/organic particles representative of biomass burning: water activity, freezing temperatures, nucleation rates.

Science.gov (United States)

Knopf, Daniel A; Rigg, Yannick J

2011-02-10

Homogeneous ice nucleation plays an important role in the formation of cirrus clouds with subsequent effects on the global radiative budget. Here we report on homogeneous ice nucleation temperatures and corresponding nucleation rate coefficients of aqueous droplets serving as surrogates of biomass burning aerosol. Micrometer-sized (NH(4))(2)SO(4)/levoglucosan droplets with mass ratios of 10:1, 1:1, 1:5, and 1:10 and aqueous multicomponent organic droplets with and without (NH(4))(2)SO(4) under typical tropospheric temperatures and relative humidities are investigated experimentally using a droplet conditioning and ice nucleation apparatus coupled to an optical microscope with image analysis. Homogeneous freezing was determined as a function of temperature and water activity, a(w), which was set at droplet preparation conditions. The ice nucleation data indicate that minor addition of (NH(4))(2)SO(4) to the aqueous organic droplets renders the temperature dependency of water activity negligible in contrast to the case of aqueous organic solution droplets. The mean homogeneous ice nucleation rate coefficient derived from 8 different aqueous droplet compositions with average diameters of ∼60 μm for temperatures as low as 195 K and a(w) of 0.82-1 is 2.18 × 10(6) cm(-3) s(-1). The experimentally derived freezing temperatures and homogeneous ice nucleation rate coefficients are in agreement with predictions of the water activity-based homogeneous ice nucleation theory when taking predictive uncertainties into account. However, the presented ice nucleation data indicate that the water activity-based homogeneous ice nucleation theory overpredicts the freezing temperatures by up to 3 K and corresponding ice nucleation rate coefficients by up to ∼2 orders of magnitude. A shift of 0.01 in a(w), which is well within the uncertainty of typical field and laboratory relative humidity measurements, brings experimental and predicted freezing temperatures and homogeneous ice

The influence of CO2 enrichment on net photosynthesis of seagrass Zostera marina in a brackish water environment

Directory of Open Access Journals (Sweden)

Liina Pajusalu

2016-11-01

Full Text Available Seagrasses are distributed across the globe and their communities may play key roles in the coastal ecosystems. Seagrass meadows are expected to benefit from the increased carbon availability which might be used in photosynthesis in a future high CO2 world. The main aim of this study was to examine the effect of elevated pCO2 on the net photosynthesis of seagrass Zostera marina in a brackish water environment. The short-term mesocosm experiments were conducted in Kõiguste Bay (northern part of Gulf of Riga, the Baltic Sea in June-July 2013 and 2014. As the levels of pCO2 naturally range from ca. 150 μatm to well above 1000 μatm under summer conditions in Kõiguste Bay we chose to operate in mesocosms with the pCO2 levels of ca. 2000, ca. 1000 and ca. 200 μatm. Additionally, in 2014 the photosynthesis of Z. marina was measured outside of the mesocosm in the natural conditions. In the shallow coastal Baltic Sea seagrass Z. marina lives in a highly variable environment due to seasonality and rapid changes in meteorological conditions. This was demonstrated by the remarkable differences in water temperatures between experimental years of ca. 8°C. Thus, the current study also investigated the effect of elevated pCO2 in combination with short-term natural fluctuations of environmental factors, i.e. temperature and PAR on the photosynthesis of Z. marina. Our results show that elevated pCO2 alone did not enhance the photosynthesis of the seagrass. The photosynthetic response of Z. marina to CO2 enrichment was affected by changes in water temperature and light availability.

Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat

Science.gov (United States)

Durner, George M.; Whiteman, J.P.; Harlow, H.J.; Amstrup, Steven C.; Regehr, E.V.; Ben-David, M.

2011-01-01

Polar bears (Ursus maritimus) prefer to live on Arctic sea ice but may swim between ice floes or between sea ice and land. Although anecdotal observations suggest that polar bears are capable of swimming long distances, no data have been available to describe in detail long distance swimming events or the physiological and reproductive consequences of such behavior. Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km. Measures of movement rate, hourly activity, and subcutaneous and external temperature revealed distinct profiles of swimming and walking. Between captures, this polar bear lost 22% of her body mass and her yearling cub. The extraordinary long distance swimming ability of polar bears, which we confirm here, may help them cope with reduced Arctic sea ice. Our observation, however, indicates that long distance swimming in Arctic waters, and travel over deep water pack ice, may result in high energetic costs and compromise reproductive fitness.

ON THE FORMATION OF INTERSTELLAR WATER ICE: CONSTRAINTS FROM A SEARCH FOR HYDROGEN PEROXIDE ICE IN MOLECULAR CLOUDS

Energy Technology Data Exchange (ETDEWEB)

Smith, R. G.; Wright, C. M.; Robinson, G. [School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600 (Australia); Charnley, S. B. [Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pendleton, Y. J. [NASA Lunar Science Institute, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Maldoni, M. M., E-mail: r.smith@adfa.edu.au, E-mail: c.wright@adfa.edu.au, E-mail: g.robinson@adfa.edu.au, E-mail: Steven.B.Charnley@nasa.gov, E-mail: yvonne.pendleton@nasa.gov [Geoscience Australia, Canberra, ACT 2601 (Australia)

2011-12-20

Recent surface chemistry experiments have shown that the hydrogenation of molecular oxygen on interstellar dust grains is a plausible formation mechanism, via hydrogen peroxide (H{sub 2}O{sub 2}), for the production of water (H{sub 2}O) ice mantles in the dense interstellar medium. Theoretical chemistry models also predict the formation of a significant abundance of H{sub 2}O{sub 2} ice in grain mantles by this route. At their upper limits, the predicted and experimental abundances are sufficiently high that H{sub 2}O{sub 2} should be detectable in molecular cloud ice spectra. To investigate this further, laboratory spectra have been obtained for H{sub 2}O{sub 2}/H{sub 2}O ice films between 2.5 and 200 {mu}m, from 10 to 180 K, containing 3%, 30%, and 97% H{sub 2}O{sub 2} ice. Integrated absorbances for all the absorption features in low-temperature H{sub 2}O{sub 2} ice have been derived from these spectra. For identifying H{sub 2}O{sub 2} ice, the key results are the presence of unique features near 3.5, 7.0, and 11.3 {mu}m. Comparing the laboratory spectra with the spectra of a group of 24 protostars and field stars, all of which have strong H{sub 2}O ice absorption bands, no absorption features are found that can definitely be identified with H{sub 2}O{sub 2} ice. In the absence of definite H{sub 2}O{sub 2} features, the H{sub 2}O{sub 2} abundance is constrained by its possible contribution to the weak absorption feature near 3.47 {mu}m found on the long-wavelength wing of the 3 {mu}m H{sub 2}O ice band. This gives an average upper limit for H{sub 2}O{sub 2}, as a percentage of H{sub 2}O, of 9% {+-} 4%. This is a strong constraint on parameters for surface chemistry experiments and dense cloud chemistry models.

An Assessment of the Icing Blade and the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

Science.gov (United States)

Steen, Laura E.; Ide, Robert F.; Van Zante, Judith Foss

2017-01-01

The Icing Research Tunnel at NASA Glenn has recently switched to from using the Icing Blade to using the SEA Multi-Element Sensor (also known as the multi-wire) for its calibration of cloud liquid water content. In order to perform this transition, tests were completed to compare the Multi-Element Sensor to the Icing Blade, particularly with respect to liquid water content, airspeed, and drop size. The two instruments were found to compare well for the majority of Appendix C conditions. However, it was discovered that the Icing Blade under-measures when the conditions approach the Ludlam Limit. This paper also describes data processing procedures for the Multi-Element Sensor in the IRT, including collection efficiency corrections, mounting underneath a splitter plate, and correcting for a jump in the compensation wire power. Further data is presented to describe the repeatability of the IRT with the Multi-Element sensor, health-monitoring checks for the instrument, and a sensing-element configuration comparison.

Protozoan Bacterivory in the Ice and the Water Column of a Cold Temperate Lagoon.

Science.gov (United States)

Sime-Ngando; Demers; Juniper

1999-02-01

> Abstract Bacterial abundance and bacterivorous protist abundance and activity were examined in ice-brine and water column communities of a cold temperate Japanese lagoon (Saroma-Ko Lagoon, Hokkaido, 44 degreesN, 144 degreesE), during the late winter phase of ice community development (February-March 1992). Bacterial abundance averaged 6 and 1 x 10(5) cells ml-1 in the ice-brine and plankton samples, respectively, and generally decreased during the sampling period. Bacterivorous protists, identified based on direct observation of short-term (Protist abundance averaged 4 x 10(3) and 8.1 cells ml-1 in the ice-brine and 0.3 x 10(3) and 1.2 cells ml-1 in the plankton, for flagellates and ciliates, respectively. In contrast to bacteria, the abundance of protists generally increased throughout the sampling period, indicating predator-prey interactions. Protistan bacterivory, measured from the rate of FLB disappearance over 24 h, averaged 36% (ice) and 24% (plankton) of bacterial standing stock and exhibited the same seasonal pattern as for protist abundance. The calculated specific clearance (range, 2-67 nl protozoa-1 h-1) and ingestion (protists" on nonbacterial food items were also provided. Although alternative sources of bacterial loss are likely to be of importance, this study provides evidence for the potential of protozoan assemblages as bacterial grazers in both sea ice-brine biota and water column at the southern limit of sea ice in the northern hemisphere.

The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

Directory of Open Access Journals (Sweden)

A. Wiacek

2010-09-01

Full Text Available This modelling study explores the availability of mineral dust particles as ice nuclei for interactions with ice, mixed-phase and liquid water clouds, also tracking the particles' history of cloud-processing. We performed 61 320 one-week forward trajectory calculations originating near the surface of major dust emitting regions in Africa and Asia using high-resolution meteorological analysis fields for the year 2007. Dust-bearing trajectories were assumed to be those coinciding with known dust emission seasons, without explicitly modelling dust emission and deposition processes. We found that dust emissions from Asian deserts lead to a higher potential for interactions with high ice clouds, despite being the climatologically much smaller dust emission source. This is due to Asian regions experiencing significantly more ascent than African regions, with strongest ascent in the Asian Taklimakan desert at ~25%, ~40% and 10% of trajectories ascending to 300 hPa in spring, summer and fall, respectively. The specific humidity at each trajectory's starting point was transported in a Lagrangian manner and relative humidities with respect to water and ice were calculated in 6-h steps downstream, allowing us to estimate the formation of liquid, mixed-phase and ice clouds. Downstream of the investigated dust sources, practically none of the simulated air parcels reached conditions of homogeneous ice nucleation (T≲−40 °C along trajectories that have not experienced water saturation first. By far the largest fraction of cloud forming trajectories entered conditions of mixed-phase clouds, where mineral dust will potentially exert the biggest influence. The majority of trajectories also passed through atmospheric regions supersaturated with respect to ice but subsaturated with respect to water, where so-called "warm ice clouds" (T≳−40 °C theoretically may form prior to supercooled water or mixed-phase clouds. The importance of "warm ice

A water activity based model of heterogeneous ice nucleation kinetics for freezing of water and aqueous solution droplets.

Science.gov (United States)

Knopf, Daniel A; Alpert, Peter A

2013-01-01

Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, a(w), which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, J(het), to be uniquely expressed by T and a(w), a result we term the a(w) based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, J(het), frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log10(J(het)) values for the various IN types derived exclusively by Tand a(w), provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Lastly, we demonstrate that ABIFM can

CHEMICAL PROCESSING OF PURE AMMONIA AND AMMONIA-WATER ICES INDUCED BY HEAVY IONS

Energy Technology Data Exchange (ETDEWEB)

Bordalo, V.; Da Silveira, E. F. [Departamento de Fisica/Laboratorio do Acelerador Van de Graaff, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marques de S. Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Lv, X. Y.; Domaracka, A.; Rothard, H.; Boduch, P. [Centre de Recherche sur les Ions, les Materiaux et la Photonique (CEA/CNRS/ENSICAEN/Universite de Caen-Basse Normandie), CIMAP-CIRIL-GANIL, Boulevard Henri Becquerel, BP 5133, F-14070 Caen Cedex 05 (France); Seperuelo Duarte, E., E-mail: vbordalo@fis.puc-rio.br [Grupo de Fisica e Astronomia, Instituto Federal do Rio de Janeiro, Rua Lucio Tavares 1045, 26530-060 Nilopolis, RJ (Brazil)

2013-09-10

Cosmic rays are possibly the main agents to prevent the freeze-out of molecules onto grain surfaces in cold dense clouds. Ammonia (NH{sub 3}) is one of the most abundant molecules present in dust ice mantles, with a concentration of up to 15% relative to water (H{sub 2}O). FTIR spectroscopy is used to monitor pure NH{sub 3} and NH{sub 3}-H{sub 2}O ice samples as they are irradiated with Ni and Zn ion beams (500-600 MeV) at GANIL/France. New species, such as hydrazine (N{sub 2}H{sub 4}), diazene (N{sub 2}H{sub 2} isomers), molecular hydrogen (H{sub 2}), and nitrogen (N{sub 2}) were identified after irradiation of pure NH{sub 3} ices. Nitrous oxide (N{sub 2}O), nitrogen oxide (NO), nitrogen dioxide (NO{sub 2}), and hydroxylamine (NH{sub 2}OH) are some of the products of the NH{sub 3}-H{sub 2}O ice radiolysis. The spectral band at 6.85 {mu}m was observed after irradiation of both types of ice. Besides the likely contribution of ammonium (NH{sub 4}{sup +}) and amino (NH{sub 2}) radicals, data suggest a small contribution of NH{sub 2}OH to this band profile after high fluences of irradiation of NH{sub 3}-H{sub 2}O ices. The spectral shift of the NH{sub 3} ''umbrella'' mode (9.3 {mu}m) band is parameterized as a function of NH{sub 3}/H{sub 2}O ratio in amorphous ices. Ammonia and water destruction cross-sections are obtained, as well as the rate of NH{sub 3}-H{sub 2}O (1:10) ice compaction, measured by the OH dangling bond destruction cross-section. Ammonia destruction is enhanced in the presence of H{sub 2}O in the ice and a power law relationship between stopping power and NH{sub 3} destruction cross-section is verified. Such results may provide relevant information for the evolution of molecular species in dense molecular clouds.

Greenhouse gas emissions from a created brackish marsh in eastern North Carolina

Science.gov (United States)

Shiau, Yo-Jin; Burchell, Michael R.; Krauss, Ken W.; Birgand, François; Broome, Stephen W.

2016-01-01

Tidal marsh creation helps remediate global warming because tidal wetlands are especially proficient at sequestering carbon (C) in soils. However, greenhouse gas (GHG) losses can offset the climatic benefits gained from C storage depending on how these tidal marshes are constructed and managed. This study attempts to determine the GHG emissions from a 4–6 year old created brackish marsh, what environmental factors governed these emissions, and how the magnitude of the fluxes relates to other wetland ecosystems. The static flux chamber method was used to measure GHG fluxes across three distinct plant zones segregated by elevation. The major of soil GHG fluxes from the marsh were from CO2 (−48–192 mg C m-2 h-1), although it was near the lower end of values reported from other wetland types having lower salinities, and would mostly be offset by photosynthetic uptake in this created brackish marsh. Methane flux was also low (−0.33–0.86 mg C m-2 h-1), likely inhibited by the high soil SO42−and soil redox potentials poised above −150 mV in this in this created brackish marsh environment. Low N2O flux (−0.11–0.10 mg N m-2 h-1) was due to low soil NO3− and soil redox conditions favoring complete denitrification. GHG fluxes from this created brackish marsh were generally lower than those recorded from natural marshes, suggesting that C sequestration may not be offset by the radiative forcing from soil GHG emissions if projects are designed properly.

Electrophysiological and behavioural responses of turbot (Scophthalmus maximus) cooled in ices water

NARCIS (Netherlands)

Lambooij, E.; Bracke, M.B.M.; Reimert, H.G.M.; Foss, A.; Imsland, A.; Vis, van de J.W.

2015-01-01

Behavioural, neural and physiological aspects related to pre-slaughter cooling of turbot habituated to two environmental temperatures (18.7 and 12.0 °C) were investigated. Six fish in both treatments were immersed in ice water for 75 min. For control, four fish were immersed in water under their

Salt partitioning between water and high-pressure ices. Implication for the dynamics and habitability of icy moons and water-rich planetary bodies

Science.gov (United States)

Journaux, Baptiste; Daniel, Isabelle; Petitgirard, Sylvain; Cardon, Hervé; Perrillat, Jean-Philippe; Caracas, Razvan; Mezouar, Mohamed

2017-04-01

Water-rich planetary bodies including large icy moons and ocean exoplanets may host a deep liquid water ocean underlying a high-pressure icy mantle. The latter is often considered as a limitation to the habitability of the uppermost ocean because it would limit the availability of nutrients resulting from the hydrothermal alteration of the silicate mantle located beneath the deep ice layer. To assess the effects of salts on the physical properties of high-pressure ices and therefore the possible chemical exchanges and habitability inside H2O-rich planetary bodies, we measured partitioning coefficients and densities in the H2O-RbI system up to 450 K and 4 GPa; RbI standing as an experimentally amenable analog of NaCl in the H2O-salt solutions. We measured the partitioning coefficient of RbI between the aqueous fluid and ices VI and VII, using in-situ Synchrotron X-ray Fluorescence (XRF). With in-situ X-ray diffraction, we measured the unit-cell parameters and the densities of the high-pressure ice phases in equilibrium with the aqueous fluid, at pressures and temperatures relevant to the interior of planetary bodies. We conclude that RbI is strongly incompatible towards ice VI with a partitioning coefficient Kd(VI-L) = 5.0 (± 2.1) ṡ10-3 and moderately incompatible towards ice VII, Kd(VII-L) = 0.12 (± 0.05). RbI significantly increases the unit-cell volume of ice VI and VII by ca. 1%. This implies that RbI-poor ice VI is buoyant compared to H2O ice VI while RbI-enriched ice VII is denser than H2O ice VII. These new experimental results might profoundly impact the internal dynamics of water-rich planetary bodies. For instance, an icy mantle at moderate conditions of pressure and temperature will consist of buoyant ice VI with low concentration of salt, and would likely induce an upwelling current of solutes towards the above liquid ocean. In contrast, a deep and/or thick icy mantle of ice VII will be enriched in salt and hence would form a stable chemical boundary

UV/Vis spectroscopy of C60 embedded in water ice

DEFF Research Database (Denmark)

Cuylle, Steven; Linnartz, Harold; Thrower, John

2012-01-01

Electronic solid state spectra are recorded for C60 embedded in 40 K water ice using broad band direct absorption spectroscopy, and assigned with reference to existing matrix data. The results are interesting in view of the recent gas phase detection of fullerenes in the interstellar medium...

Estimating Past Temperature Change in Antarctica Based on Ice Core Stable Water Isotope Diffusion

Science.gov (United States)

Kahle, E. C.; Markle, B. R.; Holme, C.; Jones, T. R.; Steig, E. J.

2017-12-01

The magnitude of the last glacial-interglacial transition is a key target for constraining climate sensitivity on long timescales. Ice core proxy records and general circulation models (GCMs) both provide insight on the magnitude of climate change through the last glacial-interglacial transition, but appear to provide different answers. In particular, the magnitude of the glacial-interglacial temperature change reconstructed from East Antarctic ice-core water-isotope records is greater ( 9 degrees C) than that from most GCM simulations ( 6 degrees C). A possible source of this difference is error in the linear-scaling of water isotopes to temperature. We employ a novel, nonlinear temperature-reconstruction technique using the physics of water-isotope diffusion to infer past temperature. Based on new, ice-core data from the South Pole, this diffusion technique suggests East Antarctic temperature change was smaller than previously thought. We are able to confirm this result using a simple, water-isotope fractionation model to nonlinearly reconstruct temperature change at ice core locations across Antarctica based on combined oxygen and hydrogen isotope ratios. Both methods produce a temperature change of 6 degrees C for South Pole, agreeing with GCM results for East Antarctica. Furthermore, both produce much larger changes in West Antarctica, also in agreement with GCM results and independent borehole thermometry. These results support the fidelity of GCMs in simulating last glacial maximum climate, and contradict the idea, based on previous work, that the climate sensitivity of current GCMs is too low.

Great Lakes Daily Ice Observations at NOAA Water Level Gauge Sites

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains daily visual ice observations taken yearly from 1 November to 30 April at NOAA/National Ocean Service water level gauge sites in the Great...

Endmembers of Ice Shelf Melt

Science.gov (United States)

Boghosian, A.; Child, S. F.; Kingslake, J.; Tedesco, M.; Bell, R. E.; Alexandrov, O.; McMichael, S.

2017-12-01

Studies of surface melt on ice shelves have defined a spectrum of meltwater behavior. On one end the storage of meltwater in persistent surface ponds can trigger ice shelf collapse as in the 2002 event leading to the disintegration of the Larsen B Ice Shelf. On the other, meltwater export by rivers can stabilize an ice shelf as was recently shown on the Nansen Ice Shelf. We explore this dichotomy by quantifying the partitioning between stored and transported water on two glaciers adjacent to floating ice shelves, Nimrod (Antarctica) and Peterman (Greenland). We analyze optical satellite imagery (LANDSAT, WorldView), airborne imagery (Operation IceBridge, Trimetrogon Aerial Phototography), satellite radar (Sentinel-1), and digital elevation models (DEMs) to categorize surface meltwater fate and map the evolution of ice shelf hydrology and topographic features through time. On the floating Peterman Glacier tongue a sizable river exports water to the ocean. The surface hydrology of Nimrod Glacier, geometrically similar to Peterman but with ten times shallower surface slope, is dominated by storage in surface lakes. In contrast, the Nansen has the same surface slope as Nimrod but transports water through surface rivers. Slope alone is not the sole control on ice shelf hydrology. It is essential to track the storage and transport volumes for each of these systems. To estimate water storage and transport we analyze high resolution (40 cm - 2 m) modern and historical DEMs. We produce historical (1957 onwards) DEMs with structure-from-motion photogrammetry. The DEMs are used to constrain water storage potential estimates of observed basins and water routing/transport potential. We quantify the total volume of water stored seasonally and interannually. We use the normalize difference water index to map meltwater extent, and estimate lake water depth from optical data. We also consider the role of stored water in subsurface aquifers in recharging surface water after

Drag Moderation by the Melting of an Ice Surface in Contact with Water

KAUST Repository

Vakarelski, Ivan Uriev; Chan, Derek Y.  C.; Thoroddsen, Sigurdur T

2015-01-01

We report measurements of the effects of a melting ice surface on the hydrodynamic drag of ice-shell-metal-core spheres free falling in water at a Reynolds of number Re∼2×104–3×105 and demonstrate that the melting surface induces the early onset of the drag crisis, thus reducing the hydrodynamic drag by more than 50%. Direct visualization of the flow pattern demonstrates the key role of surface melting. Our observations support the hypothesis that the drag reduction is due to the disturbance of the viscous boundary layer by the mass transfer from the melting ice surface.

Drag Moderation by the Melting of an Ice Surface in Contact with Water

KAUST Repository

Vakarelski, Ivan Uriev

2015-07-24

We report measurements of the effects of a melting ice surface on the hydrodynamic drag of ice-shell-metal-core spheres free falling in water at a Reynolds of number Re∼2×104–3×105 and demonstrate that the melting surface induces the early onset of the drag crisis, thus reducing the hydrodynamic drag by more than 50%. Direct visualization of the flow pattern demonstrates the key role of surface melting. Our observations support the hypothesis that the drag reduction is due to the disturbance of the viscous boundary layer by the mass transfer from the melting ice surface.

Arctic sea-ice ridges—Safe heavens for sea-ice fauna during periods of extreme ice melt?

Science.gov (United States)

Gradinger, Rolf; Bluhm, Bodil; Iken, Katrin

2010-01-01

The abundances and distribution of metazoan within-ice meiofauna (13 stations) and under-ice fauna (12 stations) were investigated in level sea ice and sea-ice ridges in the Chukchi/Beaufort Seas and Canada Basin in June/July 2005 using a combination of ice coring and SCUBA diving. Ice meiofauna abundance was estimated based on live counts in the bottom 30 cm of level sea ice based on triplicate ice core sampling at each location, and in individual ice chunks from ridges at four locations. Under-ice amphipods were counted in situ in replicate ( N=24-65 per station) 0.25 m 2 quadrats using SCUBA to a maximum water depth of 12 m. In level sea ice, the most abundant ice meiofauna groups were Turbellaria (46%), Nematoda (35%), and Harpacticoida (19%), with overall low abundances per station that ranged from 0.0 to 10.9 ind l -1 (median 0.8 ind l -1). In level ice, low ice algal pigment concentrations (Turbellaria, Nematoda and Harpacticoida also were observed in pressure ridges (0-200 ind l -1, median 40 ind l -1), although values were highly variable and only medians of Turbellaria were significantly higher in ridge ice than in level ice. Median abundances of under-ice amphipods at all ice types (level ice, various ice ridge structures) ranged from 8 to 114 ind m -2 per station and mainly consisted of Apherusa glacialis (87%), Onisimus spp. (7%) and Gammarus wilkitzkii (6%). Highest amphipod abundances were observed in pressure ridges at depths >3 m where abundances were up to 42-fold higher compared with level ice. We propose that the summer ice melt impacted meiofauna and under-ice amphipod abundance and distribution through (a) flushing, and (b) enhanced salinity stress at thinner level sea ice (less than 3 m thickness). We further suggest that pressure ridges, which extend into deeper, high-salinity water, become accumulation regions for ice meiofauna and under-ice amphipods in summer. Pressure ridges thus might be crucial for faunal survival during periods of

Produção de girassol ornamental com uso de águas salobras em sistema hidropônico NFT Production of ornamental sunflower with use of brackish waters in NFT hydroponic system

Directory of Open Access Journals (Sweden)

Marlo P Maciel

2012-02-01

Full Text Available Plantas de girassol ornamental 'Sol Vermelho' foram cultivadas em hidroponia com o objetivo de avaliar o uso de águas salobras sobre seu rendimento e qualidade da inflorescência. As águas salobras foram usadas para preparar a solução nutritiva e repor as perdas por evapotranspiração. O experimento foi conduzido em delineamento inteiramente aleatorizado com cinco níveis de salinidade da água: 1,51; 2,56; 3,86 e 6,19 dS m-1, obtidos pela adição de NaCl na água doce local (0,47 dS m-1 que também foi usada como testemunha. Cada tratamento foi repetido quatro vezes e cada parcela (com quatro plantas foi construída para simular um sistema independente da técnica do fluxo laminar de nutrientes (NFT. Observou-se uma redução linear causada pelo aumento da salinidade da água sobre a altura das plantas, o diâmetro do caule e a massa da matéria seca da parte aérea. Tanto a altura da planta quanto o diâmetro do caule foram reduzidos em 3,2% e a massa de matéria seca da parte aérea foi reduzida em 5,78% (dS m-1-1, para cada acréscimo unitário da salinidade da água (dS m-1. Por outro lado, a salinidade da água não afetou o tamanho do capítulo do girassol e não foram registrados sintomas de toxicidade causados pela salinidade. Esses resultados sustentam a viabilidade técnica do uso de águas salobras para produção hidropônica de girassol ornamental.Plants of ornamental sunflower 'Sol Vermelho' were grown under hydroponic conditions aiming to evaluate the effects of use of brackish water on its yield and inflorescence (capitulum quality. The brackish waters were utilized to prepare nutrient solution and to replace water due to evapotranspiration loss. The experiment was carried out in a completely randomized experimental design with five levels of water salinity: 1.51; 2.56; 3.86 and 6.19 dS m-1, obtained by addition of NaCl to local fresh water; this fresh water (0.47 dS m-1 was also studied as control treatment. Each

Water on Mars: Inventory, distribution, and possible sources of polar ice

Science.gov (United States)

Clifford, S. M.

1992-01-01

Theoretical considerations and various lines of morphologic evidence suggest that, in addition to the normal seasonal and climatic exchange of H2O that occurs between the Martian polar caps, atmosphere, and mid to high latitude regolith, large volumes of water have been introduced into the planet's long term hydrologic cycle by the sublimation of equatorial ground ice, impacts, catastrophic flooding, and volcanism. Under the climatic conditions that are thought to have prevailed on Mars throughout the past 3 to 4 b.y., much of this water is expected to have been cold trapped at the poles. The amount of polar ice contributed by each of the planet's potential crustal sources is discussed and estimated. The final analysis suggests that only 5 to 15 pct. of this potential inventory is now in residence at the poles.

Cloud screening and melt water detection over melting sea ice using AATSR/SLSTR

Science.gov (United States)

Istomina, Larysa; Heygster, Georg

2014-05-01

With the onset of melt in the Arctic Ocean, the fraction of melt water on sea ice, the melt pond fraction, increases. The consequences are: the reduced albedo of sea ice, increased transmittance of sea ice and affected heat balance of the system with more heat passing through the ice into the ocean, which facilitates further melting. The onset of melt, duration of melt season and melt pond fraction are good indicators of the climate state of the Arctic and its change. In the absence of reliable sea ice thickness retrievals in summer, melt pond fraction retrieval from satellite is in demand as input for GCM as an indicator of melt state of the sea ice. The retrieval of melt pond fraction with a moderate resolution radiometer as AATSR is, however, a non-trivial task due to a variety of subpixel surface types with very different optical properties, which give non-unique combinations if mixed. In this work this has been solved by employing additional information on the surface and air temperature of the pixel. In the current work, a concept of melt pond detection on sea ice is presented. The basis of the retrieval is the sensitivity of AATSR reflectance channels 550nm and 860nm to the amount of melt water on sea ice. The retrieval features extensive usage of a database of in situ surface albedo spectra. A tree of decisions is employed to select the feasible family of in situ spectra for the retrieval, depending on the melt stage of the surface. Reanalysis air temperature at the surface and brightness temperature measured by the satellite sensor are analyzed in order to evaluate the melting status of the surface. Case studies for FYI and MYI show plausible retrieved melt pond fractions, characteristic for both of the ice types. The developed retrieval can be used to process the historical AATSR (2002-2012) dataset, as well as for the SLSTR sensor onboard the future Sentinel-3 mission (scheduled for launch in 2015), to keep the continuity and obtain longer time sequence

How Will Sea Ice Loss Affect the Greenland Ice Sheet? On the Puzzling Features of Greenland Ice-Core Isotopic Composition

Science.gov (United States)

Pausata, Francesco S. R.; Legrande, Allegra N.; Roberts, William H. G.

2016-01-01

The modern cryosphere, Earth's frozen water regime, is in fast transition. Greenland ice cores show how fast theses changes can be, presenting evidence of up to 15 C warming events over timescales of less than a decade. These events, called Dansgaard/Oeschger (D/O) events, are believed to be associated with rapid changes in Arctic sea ice, although the underlying mechanisms are still unclear. The modern demise of Arctic sea ice may, in turn, instigate abrupt changes on the Greenland Ice Sheet. The Arctic Sea Ice and Greenland Ice Sheet Sensitivity (Ice2Ice Chttps://ice2ice.b.uib.noD) initiative, sponsored by the European Research Council, seeks to quantify these past rapid changes to improve our understanding of what the future may hold for the Arctic. Twenty scientists gathered in Copenhagen as part of this initiative to discuss the most recent observational, technological, and model developments toward quantifying the mechanisms behind past climate changes in Greenland. Much of the discussion focused on the causes behind the changes in stable water isotopes recorded in ice cores. The participants discussed sources of variability for stable water isotopes and framed ways that new studies could improve understanding of modern climate. The participants also discussed how climate models could provide insights into the relative roles of local and nonlocal processes in affecting stable water isotopes within the Greenland Ice Sheet. Presentations of modeling results showed how a change in the source or seasonality of precipitation could occur not only between glacial and modern climates but also between abrupt events. Recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. Further, indications from recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. This feature complicates

Decontamination and functional reclamation of dredged brackish sediments.

Science.gov (United States)

Doni, S; Macci, C; Peruzzi, E; Iannelli, R; Ceccanti, B; Masciandaro, G

2013-07-01

The continuous stream of sediments, dredged from harbors and waterways for keeping shipping traffic efficiency, is a considerable ongoing problem recognized worldwide. This problem gets worse as most of the sediments dredged from commercial ports and waterways turn out to be polluted by a wide range of organic and inorganic contaminants. In this study, phytoremediation was explored as a sustainable reclamation technology for turning slightly-polluted brackish dredged sediments into a matrix feasible for productive use. To test this possibility, a phytoremediation experimentation was carried out in containers of about 0.7 m(3) each, filled with brackish dredged sediments contaminated by heavy metals and hydrocarbons. The sediments were pre-conditioned by adding an agronomic soil (30 % v/v) to improve their clayey granulometric composition, and by topping the mixture with high quality compost (4 kg m(-2)) to favour the initial adaptation of the selected vegetal species. The following plant treatments were tested: (1) Paspalum vaginatum, (2) Phragmites australis, (3) Spartium junceum + P. vaginatum, (4) Nerium oleander + P. vaginatum, (5) Tamarix gallica + P. vaginatum, and (6) unplanted control. Eighteen months after the beginning of the experimentation, all the plant species were found in healthy condition and well developed. Throughout the whole experiment, the monitored biological parameters (total microbial population and dehydrogenase activity) were generally observed as constantly increasing in all the planted sediments more than in the control, pointing out an improvement of the chemico-physical conditions of both microorganisms and plants. The concentration decrease of organic and inorganic contaminants (>35 and 20 %, respectively) in the treatments with plants, particularly in the T. gallica + P. vaginatum, confirmed the importance of the root-microorganism interaction in activating the decontamination processes. Finally, the healthy state of

Electron Density Dropout Near Enceladus in the Context of Water-Vapor and Water-Ice

Science.gov (United States)

Farrell, W. M.; Kurth, W. S.; Gurnett, D. A.; Johnson, R. E.; Kaiser, M. L.; Wahlund, J.-E.; Waite, J. H., Jr.

2009-01-01

On 12 March 2008, the Cassini spacecraft made a close encounter with the Saturnian moon Enceladus, passing within 52 km of the moon. The spacecraft trajectory was intentionally-oriented in a southerly direction to create a close alignment with the intense water-dominated plumes emitted from the south polar region. During the passage, the Cassini Radio and Plasma Wave System (RPWS) detected two distinct radio signatures: 1) Impulses associated with small water-ice dust grain impacts and 2) an upper hybrid (UH) resonance emission that both intensified and displayed a sharp frequency decrease in the near-vicinity of the moon. The frequency decrease of the UH emission is associated with an unexpectedly sharp decrease in electron density from approximately 90 el/cubic cm to below 20 el/cubic cm that occurs on a time scale of a minute near the closest encounter with the moon. In this work, we consider a number of scenarios to explain this sharp electron dropout, but surmise that electron absorption by ice grains is the most likely process.

Atypical water lattices and their possible relevance to the amorphous ices: A density functional study

Science.gov (United States)

Anick, David J.

2013-04-01

Of the fifteen known crystalline forms of ice, eleven consist of a single topologically connected hydrogen bond network with four H-bonds at every O. The other four, Ices VI-VIII and XV, consist of two topologically connected networks, each with four H-bonds at every O. The networks interpenetrate but do not share H-bonds. This article presents two new periodic water lattice families whose topological connectivity is "atypical": they consist of many two-dimensional layers that share no H-bonds. Layers are held together only by dispersion forces. Within each layer there are still four H-bonds at each O. Called "Hexagonal Bilayer Water" (HBW) and "Pleated Sheet Water" (PSW), they have computed densities of about 1.1 g/mL and 1.3 g/mL respectively, and nearest neighbor O-coordination is 4.5 to 5.5 and 6 to 8 respectively. Using density functional theory (BLYP-D/TZVP), various proton ordered forms of HBW and PSW are optimized and categorized. There are simple pathways connecting Ice-Ih to HBW and HBW to PSW. Their computed properties suggest similarities to the high density and very high density amorphous ices (HDA and VHDA) respectively. It is unknown whether HDA, VHDA, and Low Density Amorphous Ice (LDA) are fully disordered glasses down to the molecular level, or whether there is some short-range local order. Based on estimated radial distribution functions (RDFs), one proton ordered form of HBW matches HDA best. The idea is explored that HDA could contain islands with this underlying structure, and likewise, that VHDA could contain regions of PSW. A "microlattice model version 1" (MLM1) is presented as a device to compare key experimental data on the amorphous ices with these atypical structures and with a microlattice form of Ice-XI for LDA. Resemblances are found with the amorphs' RDFs, densities, Raman spectra, and transition behaviors. There is not enough information in the static models to assign either a microlattice structure or a partial microlattice

The Regional Water Cycle and Water Ice Clouds in the Tharsis - Valles Marineris System

Science.gov (United States)

Leung, C. W. S.; Rafkin, S. C.

2017-12-01

The regional atmospheric circulation on Mars is highly influenced by local topographic gradients. Terrain-following air parcels forced along the slopes of the major Tharsis volcanoes and the steep canyon walls of Valles Marineris significantly impact the local water vapor concentration and the associated conditions for cloud formation. Using a non-hydrostatic mesoscale atmospheric model with aerosol & cloud microphysics, we investigate the meteorological conditions for water ice cloud formation in the coupled Tharsis - Valles Marineris system near the aphelion season. The usage of a limited area regional model ensures that topographic slopes are well resolved compared to the typical resolutions of a global-coverage general circulation model. The effects of shadowing and slope angle geometries on the energy budget is also taken into account. Diurnal slope winds in complex terrains are typically characterized by the reversal of wind direction twice per sol: upslope during the day, and downslope at night. However, our simulation results of the regional circulation and diurnal water cycle indicate substantial asymmetries in the day-night circulation. The convergence of moist air masses enters Valles Marineris via easterly flows, whereas dry air sweep across the plateau of the canyon system from the south towards the north. We emphasize the non-uniform vertical distribution of water vapor in our model results. Water vapor mixing ratios in the lower planetary boundary layer may be factors greater than the mixing ratio aloft. Water ice clouds are important contributors to the climatic forcing on Mars, and their effects on the mesoscale circulations in the Tharsis - Valles Marineris region significantly contribute to the regional perturbations in the large-scale global atmospheric circulation.

Petroleum activity in ice covered waters - development and operation phase. Focus of eventual consequential explanation

International Nuclear Information System (INIS)

Thomassen, J.; Andresen, K.H.; Moe, K.A.

1996-06-01

This report from a seminar relates to the petroleum activities in the Barentshavet north. The focal point was to put on petroleum activities in ice covered waters covering the drilling and operation phase, to identify discharges from various technical solutions, and to classify possible research requirements when mapping the impacts of such components. In addition to this approach, the seminar also focused on other factors regarding drilling and production activities in ice covered waters. 3 refs., 13 figs., 25 tabs

Ice sheet hydrology - a review

International Nuclear Information System (INIS)

Jansson, Peter; Naeslund, Jens-Ove; Rodhe, Lars

2007-03-01

This report summarizes the theoretical knowledge on water flow in and beneath glaciers and ice sheets and how these theories are applied in models to simulate the hydrology of ice sheets. The purpose is to present the state of knowledge and, perhaps more importantly, identify the gaps in our understanding of ice sheet hydrology. Many general concepts in hydrology and hydraulics are applicable to water flow in glaciers. However, the unique situation of having the liquid phase flowing in conduits of the solid phase of the same material, water, is not a commonly occurring phenomena. This situation means that the heat exchange between the phases and the resulting phase changes also have to be accounted for in the analysis. The fact that the solidus in the pressure-temperature dependent phase diagram of water has a negative slope provides further complications. Ice can thus melt or freeze from both temperature and pressure variations or variations in both. In order to provide details of the current understanding of water flow in conjunction with deforming ice and to provide understanding for the development of ideas and models, emphasis has been put on the mathematical treatments, which are reproduced in detail. Qualitative results corroborating theory or, perhaps more often, questioning the simplifications made in theory, are also given. The overarching problem with our knowledge of glacier hydrology is the gap between the local theories of processes and the general flow of water in glaciers and ice sheets. Water is often channelized in non-stationary conduits through the ice, features which due to their minute size relative to the size of glaciers and ice sheets are difficult to incorporate in spatially larger models. Since the dynamic response of ice sheets to global warming is becoming a key issue in, e.g. sea-level change studies, the problems of the coupling between the hydrology of an ice sheet and its dynamics is steadily gaining interest. New work is emerging

Ice sheet hydrology - a review

Energy Technology Data Exchange (ETDEWEB)

Jansson, Peter; Naeslund, Jens-Ove [Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden); Rodhe, Lars [Geological Survey of Sweden, Uppsala (Sweden)

2007-03-15

This report summarizes the theoretical knowledge on water flow in and beneath glaciers and ice sheets and how these theories are applied in models to simulate the hydrology of ice sheets. The purpose is to present the state of knowledge and, perhaps more importantly, identify the gaps in our understanding of ice sheet hydrology. Many general concepts in hydrology and hydraulics are applicable to water flow in glaciers. However, the unique situation of having the liquid phase flowing in conduits of the solid phase of the same material, water, is not a commonly occurring phenomena. This situation means that the heat exchange between the phases and the resulting phase changes also have to be accounted for in the analysis. The fact that the solidus in the pressure-temperature dependent phase diagram of water has a negative slope provides further complications. Ice can thus melt or freeze from both temperature and pressure variations or variations in both. In order to provide details of the current understanding of water flow in conjunction with deforming ice and to provide understanding for the development of ideas and models, emphasis has been put on the mathematical treatments, which are reproduced in detail. Qualitative results corroborating theory or, perhaps more often, questioning the simplifications made in theory, are also given. The overarching problem with our knowledge of glacier hydrology is the gap between the local theories of processes and the general flow of water in glaciers and ice sheets. Water is often channelized in non-stationary conduits through the ice, features which due to their minute size relative to the size of glaciers and ice sheets are difficult to incorporate in spatially larger models. Since the dynamic response of ice sheets to global warming is becoming a key issue in, e.g. sea-level change studies, the problems of the coupling between the hydrology of an ice sheet and its dynamics is steadily gaining interest. New work is emerging

Theoretical Analysis on Marangoni-driven Cavity Formation in Ice during In Situ Burning of Oil Spills in Ice-infested Waters

Science.gov (United States)

Farmahini Farahani, H.; Jomaas, G.; Rangwala, A. S.

2017-12-01

In situ burning, intentional burning of discharged oil on the water surface, is a promising response method to oil spill accidents in the Arctic. However, burning of the oil adjacent to ice bodies creates a lateral cavity in the ice. As a result of the cavity formation the removal efficiency which is a key success criterion for in situ burning operation will decrease. The formation of lateral cavities are noticed recently and only a few experimental studies have addressed them. These experiments have shown lateral cavities with a length of severe horizontal temperature gradient which in turn generates a Marangoni flow from hot to cold regions. This is found to be the dominant heat transfer mechanism that is providing the heat for the ice to melt. Here, we introduce an order of magnitude analysis on the governing equations of the ice melting problem to estimate the penetration length of a burning oil near ice. This correlation incorporates the flame heat feedback with the surface flow driven by Marangoni convection. The melting energy continuity is also included in the analysis to complete the energy transfer cycle that leads to melting of the ice. The comparison between this correlation and the existing experimental data shows a very good agreement. Therefore, this correlation can be used to estimate the penetration length for burning of an actual spill and can be applied towards improved guidelines of burning adjacent to ice bodies, so as to enhance the chances for successful implantation of in situ burning.

Adsorption and structure of water on kaolinite surfaces: possible insight into ice nucleation from grand canonical monte carlo calculations.

Science.gov (United States)

Croteau, T; Bertram, A K; Patey, G N

2008-10-30

Grand canonical Monte Carlo calculations are used to determine water adsorption and structure on defect-free kaolinite surfaces as a function of relative humidity at 235 K. This information is then used to gain insight into ice nucleation on kaolinite surfaces. Results for both the SPC/E and TIP5P-E water models are compared and demonstrate that the Al-surface [(001) plane] and both protonated and unprotonated edges [(100) plane] strongly adsorb at atmospherically relevant relative humidities. Adsorption on the Al-surface exhibits properties of a first-order process with evidence of collective behavior, whereas adsorption on the edges is essentially continuous and appears dominated by strong water lattice interactions. For the protonated and unprotonated edges no structure that matches hexagonal ice is observed. For the Al-surface some of the water molecules formed hexagonal rings. However, the a o lattice parameter for these rings is significantly different from the corresponding constant for hexagonal ice ( Ih). A misfit strain of 14.0% is calculated between the hexagonal pattern of water adsorbed on the Al-surface and the basal plane of ice Ih. Hence, the ring structures that form on the Al-surface are not expected to be good building-blocks for ice nucleation due to the large misfit strain.

Simulating Arctic clouds during Arctic Radiation- IceBridge Sea and Ice Experiment (ARISE)

Science.gov (United States)

Bromwich, D. H.; Hines, K. M.; Wang, S. H.

2015-12-01

The representation within global and regional models of the extensive low-level cloud cover over polar oceans remains a critical challenge for quantitative studies and forecasts of polar climate. In response, the polar-optimized version of the Weather Research and Forecasting model (Polar WRF) is used to simulate the meteorology, boundary layer, and Arctic clouds during the September-October 2014 Arctic Radiation- IceBridge Sea and Ice Experiment (ARISE) project. Polar WRF was developed with several adjustments to the sea ice thermodynamics in WRF. ARISE was based out of Eielson Air Force Base near Fairbanks, Alaska and included multiple instrumented C-130 aircraft flights over open water and sea ice of the Beaufort Sea. Arctic boundary layer clouds were frequently observed within cold northeasterly flow over the open ocean and ice. Preliminary results indicate these clouds were primarily liquid water, with characteristics differing between open water and sea ice surfaces. Simulated clouds are compared to ARISE observations. Furthermore, Polar WRF simulations are run for the August-September 2008 Arctic Summer Cloud Ocean Study (ASCOS) for comparison to the ARISE. Preliminary analysis shows that simulated low-level water clouds over the sea ice are too extensive during the the second half of the ASCOS field program. Alternatives and improvements to the Polar WRF cloud schemes are considered. The goal is to use the ARISE and ASCOS observations to achieve an improved polar supplement to the WRF code for open water and sea ice that can be provided to the Polar WRF community.

Influence of Sea Ice Crack Formation on the Spatial Distribution of Nutrients and Microalgae in Flooded Antarctic Multiyear Ice

Science.gov (United States)

Nomura, Daiki; Aoki, Shigeru; Simizu, Daisuke; Iida, Takahiro

2018-02-01

Cracks are common and natural features of sea ice formed in the polar oceans. In this study, a sea ice crack in flooded, multiyear, land-fast Antarctic sea ice was examined to assess its influence on biological productivity and the transport of nutrients and microalgae into the upper layers of neighboring sea ice. The water inside the crack and the surrounding host ice were characterized by a strong discoloration (brown color), an indicator of a massive algal bloom. Salinity and oxygen isotopic ratio measurements indicated that 64-84% of the crack water consisted of snow meltwater supplied during the melt season. Measurements of nutrient and chlorophyll a concentrations within the slush layer pool (the flooded layer at the snow-ice interface) revealed the intrusion of water from the crack, likely forced by mixing with underlying seawater during the tidal cycle. Our results suggest that sea ice crack formation provides conditions favorable for algal blooms by directly exposing the crack water to sunlight and supplying nutrients from the under-ice water. Subsequently, constituents of the crack water modified by biological activity were transported into the upper layer of the flooded sea ice. They were then preserved in the multiyear ice column formed by upward growth of sea ice caused by snow ice formation in areas of significant snow accumulation.

Periodic fluctuations in deep water formation due to sea ice

Science.gov (United States)

Saha, R.

2012-12-01

During the last ice age, several abrupt warming events took place, known as Dansgaard-Oeschger (D-O) events. Their effects were felt globally, although the North Atlantic experienced the largest temperature increase. The leading hypothesis to explain their occurrence postulates that the warming was caused by abrupt disruptions of the North Atlantic Current due to meltwater discharge from destabilized ice sheets (Heinrich events). However, the number of warming events outnumber the those of ice-sheet collapse. Thus, the majority of D-O events are not attributed to surface freshwater anomalies, and the underlying mechanism behind their occurrence remain unexplained. Using a simple dynamical model of sea ice and an overturning circulation, I show the existence of self-sustained relaxation oscillations in the overturning circulation. The insulating effect of sea ice is shown to paradoxically lead to a net loss of heat from the top layer of the polar ocean when sea ice retreats. Repeated heat loss results in a denser top layer and a destabilized water column, which triggers convection. The convective state pulls the system out of its preferred mode of circulation, setting up relaxation oscillations. The period of oscillations in this case is linked to the geometry of the ocean basin, if solar forcing is assumed to remain constant. If appropriate glacial freshwater forcing is applied to the model, a pattern of oscillation is produced that bears remarkable similarity to the observed fluctuations in North Atlantic climate between 50,000 and 30,000 years before present.; Comparison of NGRIP δ 18-O (proxy for near surface air temperature) between 50,000 and 30,000 years before present, showing Bond cycles (left) with the model output when forced with appropriate glacial freshwater forcing (right).

Photochemistry of PAHs in cosmic water ice. The effect of concentration on UV-VIS spectroscopy and ionization efficiency

Science.gov (United States)

Cuylle, Steven H.; Allamandola, Louis J.; Linnartz, Harold

2014-02-01

Context. Observations and models show that polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium. Like other molecules in dense clouds, PAHs accrete onto interstellar dust grains, where they are embedded in an ice matrix dominated by water. In the laboratory, mixed molecular ices (not containing PAHs) have been extensively studied using Fourier transform infrared absorption spectroscopy. Experiments including PAHs in ices have started, however, the concentrations used are typically much higher than the concentrations expected for interstellar ices. Optical spectroscopy offers a sensitive alternative. Aims: We report an experimental study of the effect PAH concentration has on the electronic spectra and the vacuum UV (VUV) driven processes of PAHs in water-rich ices. The goal is to apply the outcome to cosmic ices. Methods: Optical spectroscopic studies allow us to obtain in-situ and quasi real-time electronic solid state spectra of two prototypical PAHs (pyrene and coronene) embedded in water ice under VUV photoprocessing. The study is carried out on PAH:H2O concentrations in the range of 1:30 000 to pure PAH, covering the temperature range from 12 to 125 K. Results: PAH concentration strongly influences the efficiency of PAH cation formation. At low concentrations, ionization efficiencies are over 60% dropping to about 15% at 1:1000. Increasing the PAH concentration reveals spectral broadening in neutral and cation PAH spectra attributed to PAH clustering inside the ice. At the PAH concentrations expected for interstellar ices, some 10 to 20% may be present as cations. The presence of PAHs in neutral and ion form will add distinctive absorption bands to cosmic ice optical spectra and this may serve as a tool to determine PAH concentrations.

The Calculated and Measured Performance Characteristics of a Heated-Wire Liquid-Water-Content Meter for Measuring Icing Severity

Science.gov (United States)

Neel, Carr B.; Steinmetz, Charles P.

1952-01-01

Ground tests have been made of an instrument which, when assembled in a more compact form for flight installation, could be used to obtain statistical flight data on the liquid-water content of icing clouds and to provide an indication of icing severity. The sensing element of the instrument consists of an electrically heated wire which is mounted in the air stream. The degree of cooling of the wire resulting from evaporation of the impinging water droplets is a measure. of the liquid-water content of the cloud. Determination of the value of the liquid-water content from the wire temperature at any instant requires a knowledge of the airspeed, altitude, and air temperature. An analysis was made of the temperature response of a heated wire exposed to an air stream containing water drops. Comparisons were made of the liquid-water content as measured with several heated wires and absorbent cylinders in an artificially produced cloud. For one of the wires, comparative tests were made with a rotating-disk icing-rate meter in an icing wind tunnel. From the test results, it was shown that an instrument for measuring the concentration of liquid water in an air stream can be built using an electrically heated wire of known temperatureresistance characteristics, and that the performance of such a device can be predicted using appropriate theory. Although an instrument in a form suitable for gathering statistical data in flight was not built, the practicability of constructing such an instrument was illustrated. The ground-test results indicated that a flight heated-wire instrument would be simple and durable, would respond rapidly to variations in liquid-water content, and could be used for the measurement of water content in clouds which are above freezing temperature, as well as in icing clouds.

Ice formation in subglacial Lake Vostok, Central Antarctica

Science.gov (United States)

Souchez, R.; Petit, J. R.; Tison, J.-L.; Jouzel, J.; Verbeke, V.

2000-09-01

The investigation of chemical and isotopic properties in the lake ice from the Vostok ice core gives clues to the mechanisms involved in ice formation within the lake. A small lake water salinity can be reasonably deduced from the chemical data. Possible implications for the water circulation of Lake Vostok are developed. The characteristics of the isotopic composition of the lake ice indicate that ice formation in Lake Vostok occurred by frazil ice crystal generation due to supercooling as a consequence of rising waters and a possible contrast in water salinity. Subsequent consolidation of the developed loose ice crystals results in the accretion of ice to the ceiling of the lake.

Fire, ice, water, and dirt: A simple climate model

Science.gov (United States)

Kroll, John

2017-07-01

A simple paleoclimate model was developed as a modeling exercise. The model is a lumped parameter system consisting of an ocean (water), land (dirt), glacier, and sea ice (ice) and driven by the sun (fire). In comparison with other such models, its uniqueness lies in its relative simplicity yet yielding good results. For nominal values of parameters, the system is very sensitive to small changes in the parameters, yielding equilibrium, steady oscillations, and catastrophes such as freezing or boiling oceans. However, stable solutions can be found, especially naturally oscillating solutions. For nominally realistic conditions, natural periods of order 100kyrs are obtained, and chaos ensues if the Milankovitch orbital forcing is applied. An analysis of a truncated system shows that the naturally oscillating solution is a limit cycle with the characteristics of a relaxation oscillation in the two major dependent variables, the ocean temperature and the glacier ice extent. The key to getting oscillations is having the effective emissivity decreasing with temperature and, at the same time, the effective ocean albedo decreases with increasing glacier extent. Results of the original model compare favorably to the proxy data for ice mass variation, but not for temperature variation. However, modifications to the effective emissivity and albedo can be made to yield much more realistic results. The primary conclusion is that the opinion of Saltzman [Clim. Dyn. 5, 67-78 (1990)] is plausible that the external Milankovitch orbital forcing is not sufficient to explain the dominant 100kyr period in the data.

Fire, ice, water, and dirt: A simple climate model.

Science.gov (United States)

Kroll, John

2017-07-01

A simple paleoclimate model was developed as a modeling exercise. The model is a lumped parameter system consisting of an ocean (water), land (dirt), glacier, and sea ice (ice) and driven by the sun (fire). In comparison with other such models, its uniqueness lies in its relative simplicity yet yielding good results. For nominal values of parameters, the system is very sensitive to small changes in the parameters, yielding equilibrium, steady oscillations, and catastrophes such as freezing or boiling oceans. However, stable solutions can be found, especially naturally oscillating solutions. For nominally realistic conditions, natural periods of order 100kyrs are obtained, and chaos ensues if the Milankovitch orbital forcing is applied. An analysis of a truncated system shows that the naturally oscillating solution is a limit cycle with the characteristics of a relaxation oscillation in the two major dependent variables, the ocean temperature and the glacier ice extent. The key to getting oscillations is having the effective emissivity decreasing with temperature and, at the same time, the effective ocean albedo decreases with increasing glacier extent. Results of the original model compare favorably to the proxy data for ice mass variation, but not for temperature variation. However, modifications to the effective emissivity and albedo can be made to yield much more realistic results. The primary conclusion is that the opinion of Saltzman [Clim. Dyn. 5, 67-78 (1990)] is plausible that the external Milankovitch orbital forcing is not sufficient to explain the dominant 100kyr period in the data.

Relationship between ice water path and downward longwave radiation for clouds optically thin in the infrared: Observations and model calculations

Science.gov (United States)

Uttal, Taneil; Matrosov, Sergey Y.; Snider, Jack B.; Kropfli, Robert A.

1994-01-01

A vertically pointing 3.2-cm radar is used to observe altostratus and cirrus clouds as they pass overhead. Radar reflectivities are used in combination with an empirical Z(sub i)-IWC (ice water content) relationship developed by Sassen (1987) to parameterize IWC, which is then integrated to obtain estimates of ice water path (IWP). The observed dataset is segregated into all-ice and mixed-phase periods using measurements of integrated liquid water paths (LWP) detected by a collocated, dual-channel microwave radiometer. The IWP values for the all ice periods are compared to measurements of infrared (IR) downward fluxes measured by a collocated narrowband (9.95-11.43 microns) IR radiometer, which results in scattergrams representing the observed dependence of IR fluxes on IWP. A two-stream model is used to calculate the infrared fluxes expected from ice clouds with boundary conditions specified by the actual clouds, and similar curves relating IWP and infrared fluxes are obtained. The model and observational results suggest that IWP is one of the primary controls on infrared thermal fluxes for ice clouds.

Ice sheet hydrology from observations

Energy Technology Data Exchange (ETDEWEB)

Jansson, Peter [Dept. of Physical Geography and Quaternary Geology, Stockholm Univ-, Stockholm (Sweden)

2010-11-15

The hydrological systems of ice sheets are complex. Our view of the system is split, largely due to the complexity of observing the systems. Our basic knowledge of processes have been obtained from smaller glaciers and although applicable in general to the larger scales of the ice sheets, ice sheets contain features not observable on smaller glaciers due to their size. The generation of water on the ice sheet surface is well understood and can be satisfactorily modeled. The routing of water from the surface down through the ice is not complicated in terms of procat has been problematic is the way in which the couplings between surface and bed has been accomplished through a kilometer of cold ice, but with the studies on crack propagation and lake drainage on Greenland we are beginning to understand also this process and we know water can be routed through thick cold ice. Water generation at the bed is also well understood but the main problem preventing realistic estimates of water generation is lack of detailed information about geothermal heat fluxes and their geographical distribution beneath the ice. Although some average value for geothermal heat flux may suffice, for many purposes it is important that such values are not applied to sub-regions of significantly higher fluxes. Water generated by geothermal heat constitutes a constant supply and will likely maintain a steady system beneath the ice sheet. Such a system may include subglacial lakes as steady features and reconfiguration of the system is tied to time scales on which the ice sheet geometry changes so as to change pressure gradients in the basal system itself. Large scale re-organization of subglacial drainage systems have been observed beneath ice streams. The stability of an entirely subglacially fed drainage system may hence be perturbed by rapid ice flow. In the case of Antarctic ice streams where such behavior has been observed, the ice streams are underlain by deformable sediments. It is

Ice sheet hydrology from observations

International Nuclear Information System (INIS)

Jansson, Peter

2010-11-01

The hydrological systems of ice sheets are complex. Our view of the system is split, largely due to the complexity of observing the systems. Our basic knowledge of processes have been obtained from smaller glaciers and although applicable in general to the larger scales of the ice sheets, ice sheets contain features not observable on smaller glaciers due to their size. The generation of water on the ice sheet surface is well understood and can be satisfactorily modeled. The routing of water from the surface down through the ice is not complicated in terms of procat has been problematic is the way in which the couplings between surface and bed has been accomplished through a kilometer of cold ice, but with the studies on crack propagation and lake drainage on Greenland we are beginning to understand also this process and we know water can be routed through thick cold ice. Water generation at the bed is also well understood but the main problem preventing realistic estimates of water generation is lack of detailed information about geothermal heat fluxes and their geographical distribution beneath the ice. Although some average value for geothermal heat flux may suffice, for many purposes it is important that such values are not applied to sub-regions of significantly higher fluxes. Water generated by geothermal heat constitutes a constant supply and will likely maintain a steady system beneath the ice sheet. Such a system may include subglacial lakes as steady features and reconfiguration of the system is tied to time scales on which the ice sheet geometry changes so as to change pressure gradients in the basal system itself. Large scale re-organization of subglacial drainage systems have been observed beneath ice streams. The stability of an entirely subglacially fed drainage system may hence be perturbed by rapid ice flow. In the case of Antarctic ice streams where such behavior has been observed, the ice streams are underlain by deformable sediments. It is

Heterogeneous Ice Nucleation by Soufriere Hills Volcanic Ash Immersed in Water Droplets.

Directory of Open Access Journals (Sweden)

T P Mangan

Full Text Available Fine particles of ash emitted during volcanic eruptions may sporadically influence cloud properties on a regional or global scale as well as influencing the dynamics of volcanic clouds and the subsequent dispersion of volcanic aerosol and gases. It has been shown that volcanic ash can trigger ice nucleation, but ash from relatively few volcanoes has been studied for its ice nucleating ability. In this study we quantify the efficiency with which ash from the Soufriere Hills volcano on Montserrat nucleates ice when immersed in supercooled water droplets. Using an ash sample from the 11th February 2010 eruption, we report ice nucleating efficiencies from 246 to 265 K. This wide range of temperatures was achieved using two separate droplet freezing instruments, one employing nanolitre droplets, the other using microlitre droplets. Soufriere Hills volcanic ash was significantly more efficient than all other ash samples that have been previously examined. At present the reasons for these differences are not understood, but may be related to mineralogy, amorphous content and surface chemistry.

Heterogeneous Ice Nucleation by Soufriere Hills Volcanic Ash Immersed in Water Droplets.

Science.gov (United States)

Mangan, T P; Atkinson, J D; Neuberg, J W; O'Sullivan, D; Wilson, T W; Whale, T F; Neve, L; Umo, N S; Malkin, T L; Murray, B J

2017-01-01

Fine particles of ash emitted during volcanic eruptions may sporadically influence cloud properties on a regional or global scale as well as influencing the dynamics of volcanic clouds and the subsequent dispersion of volcanic aerosol and gases. It has been shown that volcanic ash can trigger ice nucleation, but ash from relatively few volcanoes has been studied for its ice nucleating ability. In this study we quantify the efficiency with which ash from the Soufriere Hills volcano on Montserrat nucleates ice when immersed in supercooled water droplets. Using an ash sample from the 11th February 2010 eruption, we report ice nucleating efficiencies from 246 to 265 K. This wide range of temperatures was achieved using two separate droplet freezing instruments, one employing nanolitre droplets, the other using microlitre droplets. Soufriere Hills volcanic ash was significantly more efficient than all other ash samples that have been previously examined. At present the reasons for these differences are not understood, but may be related to mineralogy, amorphous content and surface chemistry.

The ancient heritage of water ice in the solar system.

Science.gov (United States)

Cleeves, L Ilsedore; Bergin, Edwin A; Alexander, Conel M O'D; Du, Fujun; Graninger, Dawn; Öberg, Karin I; Harries, Tim J

2014-09-26

Identifying the source of Earth's water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-to-hydrogen enrichments, a fossil relic of low-temperature, ion-derived chemistry within either (i) the parent molecular cloud or (ii) the solar nebula protoplanetary disk. Using a comprehensive treatment of disk ionization, we find that ion-driven deuterium pathways are inefficient, which curtails the disk's deuterated water formation and its viability as the sole source for the solar system's water. This finding implies that, if the solar system's formation was typical, abundant interstellar ices are available to all nascent planetary systems. Copyright © 2014, American Association for the Advancement of Science.

Water droplet behavior on superhydrophobic SiO2 nanocomposite films during icing/deicing cycles

NARCIS (Netherlands)

Lazauskas, A.; Guobiene, A.; Prosycevas, I.; Baltrusaitis, V.; Grigaliunas, V.; Narmontas, P.; Baltrusaitis, Jonas

2013-01-01

This work investigates water droplet behavior on superhydrophobic (water contact angle value of 162 ± 1°) SiO2 nanocomposite films subjected to repetitive icing/deicing treatments, changes in SiO2 nanocomposite film surface morphology and their non-wetting characteristics. During the experiment,

Effects of sea-ice and biogeochemical processes and storms on under-ice water fCO2 during the winter-spring transition in the high Arctic Ocean: Implications for sea-air CO2 fluxes

Science.gov (United States)

Fransson, Agneta; Chierici, Melissa; Skjelvan, Ingunn; Olsen, Are; Assmy, Philipp; Peterson, Algot K.; Spreen, Gunnar; Ward, Brian

2017-07-01

We performed measurements of carbon dioxide fugacity (fCO2) in the surface water under Arctic sea ice from January to June 2015 during the Norwegian young sea ICE (N-ICE2015) expedition. Over this period, the ship drifted with four different ice floes and covered the deep Nansen Basin, the slopes north of Svalbard, and the Yermak Plateau. This unique winter-to-spring data set includes the first winter-time under-ice water fCO2 observations in this region. The observed under-ice fCO2 ranged between 315 µatm in winter and 153 µatm in spring, hence was undersaturated relative to the atmospheric fCO2. Although the sea ice partly prevented direct CO2 exchange between ocean and atmosphere, frequently occurring leads and breakup of the ice sheet promoted sea-air CO2 fluxes. The CO2 sink varied between 0.3 and 86 mmol C m-2 d-1, depending strongly on the open-water fractions (OW) and storm events. The maximum sea-air CO2 fluxes occurred during storm events in February and June. In winter, the main drivers of the change in under-ice water fCO2 were dissolution of CaCO3 (ikaite) and vertical mixing. In June, in addition to these processes, primary production and sea-air CO2 fluxes were important. The cumulative loss due to CaCO3 dissolution of 0.7 mol C m-2 in the upper 10 m played a major role in sustaining the undersaturation of fCO2 during the entire study. The relative effects of the total fCO2 change due to CaCO3 dissolution was 38%, primary production 26%, vertical mixing 16%, sea-air CO2 fluxes 16%, and temperature and salinity insignificant.

3 micron spectrophotometry of Comet Halley - Evidence for water ice

Science.gov (United States)

Bregman, Jesse D.; Tielens, A. G. G. M.; Witteborn, Fred C.; Rank, David M.; Wooden, Diane

1988-01-01

Structure has been observed in the 3-3.6 micron preperihelion spectrum of Comet Halley consistent with either an absorption band near 3.1 microns or emission near 3.3 microns. The results suggest that a large fraction of the water molecules lost by the comet are initially ejected in the form of small ice particles rather than in the gas phase.

A modified QWASI model for fate and transport modeling of mercury between the water-ice-sediment in Lake Ulansuhai.

Science.gov (United States)

Liu, Yu; Li, Changyou; Anderson, Bruce; Zhang, Sheng; Shi, Xiaohong; Zhao, Shengnan

2017-06-01

Mercury contamination from industrial and agricultural drainage into lakes and rivers is a growing concern in Northern China. Lake Ulansuhai, located in Hetao irrigation district in Inner Mongolia, is the only sink for the all industrial and agricultural drainage and sole outlet for this district to the Yellow River, which is one of the main source of drinking water for the numerous cities and towns downstream. Because Ulansuahi is ice-covered during winter, the QWASI model was modified by adding an ice equation to get a more accurate understanding of the fate and transport of mercury within the lake. Both laboratory and field tests were carried out during the ice growth period. The aquivalence and mass balance approaches were used to develop the modified QWASI + ice model. The margins of error between the modelled and the measured average concentrations of Hg in ice, water, and sediment were 30%, 26.2%, and 19.8% respectively. These results suggest that the new QWASI + ice model could be used to more accurately represent the fate and transport of mercury in the seasonally ice-covered lakes, during the ice growth period. Copyright © 2017 Elsevier Ltd. All rights reserved.

Membrane scaling and flux decline during fertiliser-drawn forward osmosis desalination of brackish groundwater.

Science.gov (United States)

Phuntsho, Sherub; Lotfi, Fezeh; Hong, Seungkwan; Shaffer, Devin L; Elimelech, Menachem; Shon, Ho Kyong

2014-06-15

Fertiliser-drawn forward osmosis (FDFO) desalination has been recently studied as one feasible application of forward osmosis (FO) for irrigation. In this study, the potential of membrane scaling in the FDFO process has been investigated during the desalination of brackish groundwater (BGW). While most fertilisers containing monovalent ions did not result in any scaling when used as an FO draw solution (DS), diammonium phosphate (DAP or (NH4)2HPO4) resulted in significant scaling, which contributed to severe flux decline. Membrane autopsy using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) analysis indicated that the reverse diffusion of DAP from the DS to the feed solution was primarily responsible for scale formation during the FDFO process. Physical cleaning of the membrane with deionised water at varying crossflow velocities was employed to evaluate the reversibility of membrane scaling and the extent of flux recovery. For the membrane scaled using DAP as DS, 80-90% of the original flux was recovered when the crossflow velocity for physical cleaning was the same as the crossflow velocity during FDFO desalination. However, when a higher crossflow velocity or Reynolds number was used, the flux was recovered almost completely, irrespective of the DS concentration used. This study underscores the importance of selecting a suitable fertiliser for FDFO desalination of brackish groundwater to avoid membrane scaling and severe flux decline. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ice-water convection in an inclined rectangular cavity filled with a porous medium

Energy Technology Data Exchange (ETDEWEB)

Zhang, X. (Dept. of Mechanical Engineering, Ecole Polytechnique de Montreal (Canada)); Kahawita, R. (Dept. of Civil Engineering, Ecole Polytechnique de Montreal (Canada))

1994-10-01

This paper reports on the results of a numerical study on the equilibrium state of the convection of water in the presence of ice in an inclined rectangular cavity filled with a porous medium. One side of the cavity is maintained at a temperature higher than the fusion temperature while the opposite side is cooled to a temperature lower than the fusion temperature. The two remaining sides are insulated. Results are analysed in terms of the density inversion parameter, the tilt angle, and the cooling temperature. It appears that the phenomenon of density inversion plays an important role in the equilibrium of an ice-water system when the heating temperature is below 20 . In a vertical cavity, the density inversion causes the formation of two counter-rotating vortices leading to a water volume which is wider at the bottom than at the top. When the cavity is inclined, there exist two branches of solutions which exhibit the bottom heating and the side heating characteristics, respectively (the Benard and side heating branches). Due to the inversion of density, the solution on the Benard branch may fail to converge to a steady state at small tilt angles and exhibits an oscillating behavior. On the side heating branch, a maximum heat transfer rate is obtained at a tilt angle of about 70 but the water volume was found to depend very weakly on the inclination of the cavity. Under the effect of subcooling, the interplay between conduction in the solid phase and convection in the liquid leads to an equilibrium ice-water interface which is most distorted at some intermediate cooling temperature. (orig.)

Temperature distribution of a water droplet moving on a heated super-hydrophobic surface under the icing condition

Science.gov (United States)

Yamazaki, Masafumi; Sumino, Yutaka; Morita, Katsuaki

2017-11-01

In the aviation industry, ice accretion on the airfoil has been a hazardous issue since it greatly declines the aerodynamic performance. Electric heaters and bleed air, which utilizes a part of gas emissions from engines, are used to prevent the icing. Nowadays, a new de-icing system combining electric heaters and super hydrophobic coatings have been developed to reduce the energy consumption. In the system, the heating temperature and the coating area need to be adjusted. Otherwise, the heater excessively consumes energy when it is set too high and when the coating area is not properly located, water droplets which are once dissolved possibly adhere again to the rear part of the airfoil as runback ice In order to deal with these problems, the physical phenomena of water droplets on the hydrophobic surface demand to be figured out. However, not many investigations focused on the behavior of droplets under the icing condition have been conducted. In this research, the temperature profiling of the rolling droplet on a heated super-hydrophobic surface is experimentally observed by the dual luminescent imaging.

Influence of sea ice cover and icebergs on circulation and water mass formation in a numerical circulation model of the Ross Sea, Antarctica

Science.gov (United States)

Dinniman, Michael S.; Klinck, John M.; Smith, Walker O.

2007-11-01

Satellite imagery shows that there was substantial variability in the sea ice extent in the Ross Sea during 2001-2003. Much of this variability is thought to be due to several large icebergs that moved through the area during that period. The effects of these changes in sea ice on circulation and water mass distributions are investigated with a numerical general circulation model. It would be difficult to simulate the highly variable sea ice from 2001 to 2003 with a dynamic sea ice model since much of the variability was due to the floating icebergs. Here, sea ice concentration is specified from satellite observations. To examine the effects of changes in sea ice due to iceberg C-19, simulations were performed using either climatological ice concentrations or the observed ice for that period. The heat balance around the Ross Sea Polynya (RSP) shows that the dominant term in the surface heat budget is the net exchange with the atmosphere, but advection of oceanic warm water is also important. The area average annual basal melt rate beneath the Ross Ice Shelf is reduced by 12% in the observed sea ice simulation. The observed sea ice simulation also creates more High-Salinity Shelf Water. Another simulation was performed with observed sea ice and a fixed iceberg representing B-15A. There is reduced advection of warm surface water during summer from the RSP into McMurdo Sound due to B-15A, but a much stronger reduction is due to the late opening of the RSP in early 2003 because of C-19.

Evidence for ice-ocean albedo feedback in the Arctic Ocean shifting to a seasonal ice zone.

Science.gov (United States)

Kashiwase, Haruhiko; Ohshima, Kay I; Nihashi, Sohey; Eicken, Hajo

2017-08-15

Ice-albedo feedback due to the albedo contrast between water and ice is a major factor in seasonal sea ice retreat, and has received increasing attention with the Arctic Ocean shifting to a seasonal ice cover. However, quantitative evaluation of such feedbacks is still insufficient. Here we provide quantitative evidence that heat input through the open water fraction is the primary driver of seasonal and interannual variations in Arctic sea ice retreat. Analyses of satellite data (1979-2014) and a simplified ice-upper ocean coupled model reveal that divergent ice motion in the early melt season triggers large-scale feedback which subsequently amplifies summer sea ice anomalies. The magnitude of divergence controlling the feedback has doubled since 2000 due to a more mobile ice cover, which can partly explain the recent drastic ice reduction in the Arctic Ocean.

Origin of brackish groundwater in a sandstone aquifer on Bornholm, Denmark

DEFF Research Database (Denmark)

Jørgensen, Niels Oluf; Heinemeier, Jan

2008-01-01

A multi-isotope approach in combination with hydrochemical data and borehole logging is applied to identify the source of brackish groundwater in a borehole in the well field of Neksø Municipal Waterworks in Bornholm, Denmark. The aquifer lithology consists of fractured Lower Cambrian sandstones...

An Assessment of the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

Science.gov (United States)

Steen, Laura E.; Ide, Robert F.; Van Zante, Judith F.

2015-01-01

The NASA Glenn Icing Research tunnel has been using an Icing Blade technique to measure cloud liquid water content (LWC) since 1980. The IRT conducted tests with SEA Multi-Element sensors from 2009 to 2011 to assess their performance in measuring LWC. These tests revealed that the Multi-Element sensors showed some significant advantages over the Icing Blade, particularly at higher water contents, higher impingement rates, and large drop sizes. Results of these and other tests are presented here.

GLERL Radiation Transfer Through Freshwater Ice

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Radiation transmittance (ratio of transmitted to incident radiation) through clear ice, refrozen slush ice and brash ice, from ice surface to ice-water interface in...

The photoexcitation of crystalline ice and amorphous solid water: A molecular dynamics study of outcomes at 11 K and 125 K

Energy Technology Data Exchange (ETDEWEB)

Crouse, J.; Loock, H.-P., E-mail: hploock@chem.queensu.ca; Cann, N. M., E-mail: ncann@chem.queensu.ca [Department of Chemistry, Queen’s University, Kingston, Ontario K7L 3N6 (Canada)

2015-07-21

Photoexcitation of crystalline ice Ih and amorphous solid water at 7-9 eV is examined using molecular dynamics simulations and a fully flexible water model. The probabilities of photofragment desorption, trapping, and recombination are examined for crystalline ice at 11 K and at 125 K and for amorphous solid water at 11 K. For 11 K crystalline ice, a fully rigid water model is also employed for comparison. The kinetic energy of desorbed H atoms and the distance travelled by trapped fragments are correlated to the location and the local environment of the photoexcited water molecule. In all cases, H atom desorption is found to be the most likely outcome in the top bilayer while trapping of all photofragments is most probable deeper in the solid where the likelihood for recombination of the fragments into H{sub 2}O molecules also rises. Trajectory analysis indicates that the local hydrogen bonding network in amorphous solid water is more easily distorted by a photodissociation event compared to crystalline ice. Also, simulations indicate that desorption of OH radicals and H{sub 2}O molecules are more probable in amorphous solid water. The kinetic energy distributions for desorbed H atoms show a peak at high energy in crystalline ice, arising from photoexcited water molecules in the top monolayer. This peak is less pronounced in amorphous solid water. H atoms that are trapped may be displaced by up to ∼10 water cages, but migrate on average 3 water cages. Trapped OH fragments tend to stay near the original solvent cage.

REGULARITIES OF CONGELATION ICE DEVELOPMENT IN SUBGLACIAL LAKE VOSTOK

Directory of Open Access Journals (Sweden)

V. Ya. Lipenkov

2012-01-01

Full Text Available Petrographic studies performed on the continuous basis along the two ice cores obtained from holes 5G-1 and 5G-2 at Vostok Station has allowed to characterize with great details the evolution of the ice texture and fabric in the 232-m thick stratum of accreted ice formed from theLakeVostokwater. Conventionally the whole thickness of accreted ice is divided into two strata: lake ice 1 and lake ice 2. Lake ice 1 (3537–3618 m, formed in the sallow strait50 kmupstream of Vostok, is characterized by presence of disseminated mineral inclusions of Lake Vostok sediments, as well as of «water pockets» that represent frozen water inclusions trapped during the ice accretion. The latter constitute less than 1% of the total ice volume, their mean size is about0.5 cm. Gases trapped by «water pockets» during ice formation transform into crystalline inclusions of mixed gas hydrates. Accretion of lake ice 2 (3618–3769 m proceeds in the deep part of the lake at a very small rate that does not assume trapping of liquid water inclusions and gases.Both strata of accreted ice are formed by orthotropic crystal growth from pure water. The main tendency in the evolution of accreted ice texture is growth of the mean crystal size with depth as the lake ice becomes younger towards the ice-water interface. The high-amplitude variations of crystal size and orientation observed around this general trend are shown to be linked with temporal and spatial variability of the supercooled melt-water flux from the northern part of the lake towards the ice formation site. The presence of supercooled water at the crystallization front supports persistent preferable growth of ice crystals with sub-horizontally oriented c-axes. The lack of supercooled water in turn support persistent growth of ice crystals with vertical or inclined with respect to the crystallization front c-axis orientation. It means that each of these preferred fabric orientations could serve as an indicator of

Report on follow-up for joint research of valuable resources recovery techniques from brackish water; Kansuichu no yuka shigen kaishu gijutsu ni kansuru kenkyu kyoryoku follow up hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

This report describes follow-up for research and development on the recovery of valuable resources, such as magnesium, bromine and boron, contained in the brackish water for manufacture of common salt in the coastal region of Mexico. For the field survey, salt garden, irrigation plant and manufacturing plant of dinning salt were inspected. The optimum site was examined by assuming desalination plant and solar pond. The groundwater in coastal regions is progressively salified. Since the coastal region is a tourist resort with an round-trip area of whales, environmental protection is indispensable. For the joint research with invited researchers, the solar pond system and fresh water generation were studied. As a result, it was found that the solar pond system is an excellent method for keeping thermal energy in a low cost at the salt garden with abundant solar energy, and that the desalination system combined with distilling is the most suitable method. 7 refs., 8 figs., 1 tab.

Great Lakes Daily Ice Observations at NOAA Water Level Gauge Sites, Version 1

Data.gov (United States)

National Aeronautics and Space Administration — This data set contains daily visual ice observations taken yearly from 1 November to 30 April at NOAA/National Ocean Service water level gauge sites in the Great...

Dielectric constant and low-frequency infrared spectra for liquid water and ice Ih within the E3B model

Energy Technology Data Exchange (ETDEWEB)

Shi, L.; Ni, Y.; Drews, S. E. P.; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

2014-08-28

Two intrinsic difficulties in modeling condensed-phase water with conventional rigid non-polarizable water models are: reproducing the static dielectric constants for liquid water and ice Ih, and generating the peak at about 200 cm{sup −1} in the low-frequency infrared spectrum for liquid water. The primary physical reason for these failures is believed to be the missing polarization effect in these models, and consequently various sophisticated polarizable water models have been developed. However, in this work we pursue a different strategy and propose a simple empirical scheme to include the polarization effect only on the dipole surface (without modifying a model's intermolecular interaction potential). We implement this strategy for our explicit three-body (E3B) model. Our calculated static dielectric constants and low-frequency infrared spectra are in good agreement with experiment for both liquid water and ice Ih over wide temperature ranges, albeit with one fitting parameter for each phase. The success of our modeling also suggests that thermal fluctuations about local minima and the energy differences between different proton-disordered configurations play minor roles in the static dielectric constant of ice Ih. Our analysis shows that the polarization effect is important in resolving the two difficulties mentioned above and sheds some light on the origin of several features in the low-frequency infrared spectra for liquid water and ice Ih.

Fungal spores as potential ice nuclei in fog/cloud water and snow

Science.gov (United States)

Bauer, Heidi; Goncalves, Fabio L. T.; Schueller, Elisabeth; Puxbaum, Hans

2010-05-01

INTRODUCTION: In discussions about climate change and precipitation frequency biological ice nucleation has become an issue. While bacterial ice nucleation (IN) is already well characterized and even utilized in industrial processes such as the production of artificial snow or to improve freezing processes in food industry, less is known about the IN potential of fungal spores which are also ubiquitous in the atmosphere. A recent study performed at a mountain top in the Rocky Mountains suggests that fungal spores and/or pollen might play a role in increased IN abundance during periods of cloud cover (Bowers et al. 2009). In the present work concentrations of fungal spores in fog/cloud water and snow were determined. EXPERIMENTAL: Fog samples were taken with an active fog sampler in 2008 in a traffic dominated area and in a national park in São Paulo, Brazil. The number concentrations of fungal spores were determined by microscopic by direct enumeration by epifluorescence microscopy after staining with SYBR Gold nucleic acid gel stain (Bauer et al. 2008). RESULTS: In the fog water collected in the polluted area at a junction of two highly frequented highways around 22,000 fungal spores mL-1 were counted. Fog in the national park contained 35,000 spores mL-1. These results were compared with cloud water and snow samples from Mt. Rax, situated at the eastern rim of the Austrian Alps. Clouds contained on average 5,900 fungal spores mL-1 cloud water (1,300 - 11,000) or 2,200 spores m-3 (304 - 5,000). In freshly fallen snow spore concentrations were lower than in cloud water, around 1,000 fungal spores mL-1 were counted (Bauer et al. 2002). In both sets of samples representatives of the ice nucleating genus Fusarium could be observed. REFERENCES: Bauer, H., Kasper-Giebl, A., Löflund, M., Giebl, H., Hitzenberger, R., Zibuschka, F., Puxbaum, H. (2002). The contribution of bacteria and fungal spores to the organic carbon content of cloud water, precipitation and aerosols

Nuclear Data Libraries for Hydrogen in Light Water Ice

International Nuclear Information System (INIS)

Torres, L; Gillette, V.H

2000-01-01

Nuclear data libraries were produced for hydrogen (H) in light water ice at different temperatures, 20, 30, 50, 77, 112, 180, 230 K.These libraries were produced using the NJOY nuclear data processing system.With this code we produce pointwise cross sections and related quantities, in the ENDF format, and in the ACE format for MCNP.Experimental neutron spectra at such temperatures were compared with MCNP4B simulations, based on the locally produced libraries, leading to satisfactory results

Subglacial hydrology and the formation of ice streams.

Science.gov (United States)

Kyrke-Smith, T M; Katz, R F; Fowler, A C

2014-01-08

Antarctic ice streams are associated with pressurized subglacial meltwater but the role this water plays in the dynamics of the streams is not known. To address this, we present a model of subglacial water flow below ice sheets, and particularly below ice streams. The base-level flow is fed by subglacial melting and is presumed to take the form of a rough-bedded film, in which the ice is supported by larger clasts, but there is a millimetric water film which submerges the smaller particles. A model for the film is given by two coupled partial differential equations, representing mass conservation of water and ice closure. We assume that there is no sediment transport and solve for water film depth and effective pressure. This is coupled to a vertically integrated, higher order model for ice-sheet dynamics. If there is a sufficiently small amount of meltwater produced (e.g. if ice flux is low), the distributed film and ice sheet are stable, whereas for larger amounts of melt the ice-water system can become unstable, and ice streams form spontaneously as a consequence. We show that this can be explained in terms of a multi-valued sliding law, which arises from a simplified, one-dimensional analysis of the coupled model.

Astronomical Ice: The Effects of Treating Ice as a Porous Media on the Dynamics and Evolution of Extraterrestrial Ice-Ocean Environments

Science.gov (United States)

Buffo, J.; Schmidt, B. E.

2015-12-01

With the prevalence of water and ice rich environments in the solar system, and likely the universe, becoming more apparent, understanding the evolutionary dynamics and physical processes of such locales is of great importance. Piqued interest arises from the understanding that the persistence of all known life depends on the presence of liquid water. As in situ investigation is currently infeasible, accurate numerical modeling is the best technique to demystify these environments. We will discuss an evolving model of ice-ocean interaction aimed at realistically describing the behavior of the ice-ocean interface by treating basal ice as a porous media, and its possible implications on the formation of astrobiological niches. Treating ice as a porous media drastically affects the thermodynamic properties it exhibits. Thus inclusion of this phenomenon is critical in accurately representing the dynamics and evolution of all ice-ocean environments. This model utilizes equations that describe the dynamics of sea ice when it is treated as a porous media (Hunke et. al. 2011), coupled with a basal melt and accretion model (Holland and Jenkins 1999). Combined, these two models produce the most accurate description of the processes occurring at the base of terrestrial sea ice and ice shelves, capable of resolving variations within the ice due to environmental pressures. While these models were designed for application to terrestrial environments, the physics occurring at any ice-water interface is identical, and these models can be used to represent the evolution of a variety of icy astronomical bodies. As terrestrial ice shelves provide a close analog to planetary ice-ocean environments, we truth test the models validity against observations of ice shelves. We apply this model to the ice-ocean interface of the icy Galilean moon Europa. We include profiles of temperature, salinity, solid fraction, and Darcy velocity, as well as temporally and spatially varying melt and

Water-Searchers: A Reconfigurable and Self Sustaining Army of Subsurface Exploration Robots Searching for Water/Ice Using Multiple Sensors

Science.gov (United States)

Youk, G. U.; Whittaker, W. (Red); Volpe, R.

2000-01-01

Perhaps the most promising site for extant life on Mars today is where subsurface water has been maintained. Therefore, searching for underground water will provide a good chance to find evidence of life on Mars. The following are scientific/engineering questions that we want to answer using our approach: (1) Is there subsurface water/ice? How deep is it? How much is there? Is it frozen? (2) What kinds of underground layers exist in the Martian crust? (3) What is the density of Martian soil or regolith? Can we dig into it? Should we drill into it? (4) Can a sudden release of underground water occur if a big asteroid hits Mars? Our approach provides essential information to answer these questions. Moreover, dependence on the water content and depth in soil, not only resultant scientific conclusions but also proper digging/drilling methods, are suggested. 'How much water is in the Martian soil?' There can be several possibilities: (1) high water content that is enough to form permafrost; (2) low water content that is not enough to form permafrost; or (3) different layers with different moisture contents. 'How deep should a rover dig into soil to find water/ice?' The exact size-frequency distribution has not been measured for the soil particles. On-board sensors can provide not only the water content but also the density (or porosity) of Martian soil as a function of depth.

Diazotroph Diversity in the Sea Ice, Melt Ponds, and Surface Waters of the Eurasian Basin of the Central Arctic Ocean.

Science.gov (United States)

Fernández-Méndez, Mar; Turk-Kubo, Kendra A; Buttigieg, Pier L; Rapp, Josephine Z; Krumpen, Thomas; Zehr, Jonathan P; Boetius, Antje

2016-01-01

The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing toward a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77°N. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

Diazotroph diversity in the sea ice, melt ponds and surface waters of the Eurasian Basin of the Central Arctic Ocean

Directory of Open Access Journals (Sweden)

Mar Fernández-Méndez

2016-11-01

Full Text Available The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme. We amplified 529 nifH sequences from 26 samples of Arctic melt ponds, sea ice and surface waters. These sequences resolved into 43 clusters at 92% amino acid sequence identity, most of which were non-cyanobacterial phylotypes from sea ice and water samples. One cyanobacterial phylotype related to Nodularia sp. was retrieved from sea ice, suggesting that this important functional group is rare in the Central Arctic Ocean. The diazotrophic community in sea-ice environments appear distinct from other cold-adapted diazotrophic communities, such as those present in the coastal Canadian Arctic, the Arctic tundra and glacial Antarctic lakes. Molecular fingerprinting of nifH and the intergenic spacer region of the rRNA operon revealed differences between the communities from river-influenced Laptev Sea waters and those from ice-related environments pointing towards a marine origin for sea-ice diazotrophs. Our results provide the first record of diazotrophs in the Central Arctic and suggest that microbial nitrogen fixation may occur north of 77ºN. To assess the significance of nitrogen fixation for the nitrogen budget of the Arctic Ocean and to identify the active nitrogen fixers, further biogeochemical and molecular biological studies are needed.

SHARAD detection and characterization of subsurface water ice deposits in Utopia Planitia, Mars

Science.gov (United States)

Stuurman, C. M.; Osinski, G. R.; Holt, J. W.; Levy, J. S.; Brothers, T. C.; Kerrigan, M.; Campbell, B. A.

2016-09-01

Morphological analyses of Utopia Planitia, Mars, have led to the hypothesis that the region contains a substantial amount of near-surface ice. This paper tests this hypothesis using ground-penetrating radar techniques. We have identified an expansive radar reflective region spanning approximately 375,000 km2 in SHAllow RADar (SHARAD) data over western Utopia Planitia. The SHARAD reflective regions coincides with high densities of scalloped depressions and polygonal terrain. The reflectors are associated with layered mesas ˜80-170 m thick. We find a value of 2.8 ± 0.8 for the dielectric constant of the material overlying the reflectors. This work finds that the dielectric constant is consistent with a mixture of ice, air, and dust, containing a water ice volume up to 14,300 km3 in this unit.

Cascading water underneath Wilkes Land, East Antarctic ice sheet, observed using altimetry and digital elevation models

Science.gov (United States)

Flament, T.; Berthier, E.; Rémy, F.

2014-04-01

We describe a major subglacial lake drainage close to the ice divide in Wilkes Land, East Antarctica, and the subsequent cascading of water underneath the ice sheet toward the coast. To analyse the event, we combined altimetry data from several sources and subglacial topography. We estimated the total volume of water that drained from Lake CookE2 by differencing digital elevation models (DEM) derived from ASTER and SPOT5 stereo imagery acquired in January 2006 and February 2012. At 5.2 ± 1.5 km3, this is the largest single subglacial drainage event reported so far in Antarctica. Elevation differences between ICESat laser altimetry spanning 2003-2009 and the SPOT5 DEM indicate that the discharge started in November 2006 and lasted approximately 2 years. A 13 m uplift of the surface, corresponding to a refilling of about 0.6 ± 0.3 km3, was observed between the end of the discharge in October 2008 and February 2012. Using the 35-day temporal resolution of Envisat radar altimetry, we monitored the subsequent filling and drainage of connected subglacial lakes located downstream of CookE2. The total volume of water traveling within the theoretical 500-km-long flow paths computed with the BEDMAP2 data set is similar to the volume that drained from Lake CookE2, and our observations suggest that most of the water released from Lake CookE2 did not reach the coast but remained trapped underneath the ice sheet. Our study illustrates how combining multiple remote sensing techniques allows monitoring of the timing and magnitude of subglacial water flow beneath the East Antarctic ice sheet.

On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

Directory of Open Access Journals (Sweden)

J.-F. Gayet

2012-01-01

Full Text Available During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/−58 °C. The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C and nadir looking remote sensing observations (DLR WALES Lidar. Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm⁻³, 30 km⁻¹ and 0.5 g m⁻³, respectively are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved

On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

Science.gov (United States)

Gayet, J.-F.; Mioche, G.; Bugliaro, L.; Protat, A.; Minikin, A.; Wirth, M.; Dörnbrack, A.; Shcherbakov, V.; Mayer, B.; Garnier, A.; Gourbeyre, C.

2012-01-01

During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/-58 °C). The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C) and nadir looking remote sensing observations (DLR WALES Lidar). Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm-3, 30 km-1 and 0.5 g m-3, respectively) are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC) and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved IWC up to 1 g m-3 may be observed near the cloud top

A simple trapping method of exhaled water using an ice-cooled tube to monitor the tritium level in human body

International Nuclear Information System (INIS)

Nogawa, Norio; Makide, Yoshihiro

1994-01-01

A convenient and efficient method is developed for the trapping of water in exhaled air. A bent-V-shaped glass sampling tube was immersed in iced water and exhaled air was introduced into the tube through a plastic straw. The trapping efficiency of exhaled water was equivalent to those with more complex and troublesome methods. Using anywhere available ice, the water in exhaled air can be rapidly collected with this method and the tritium level in the body will be quickly obtained. (author)

Ice nucleation triggered by negative pressure.

Science.gov (United States)

Marcolli, Claudia

2017-11-30

Homogeneous ice nucleation needs supercooling of more than 35 K to become effective. When pressure is applied to water, the melting and the freezing points both decrease. Conversely, melting and freezing temperatures increase under negative pressure, i.e. when water is stretched. This study presents an extrapolation of homogeneous ice nucleation temperatures from positive to negative pressures as a basis for further exploration of ice nucleation under negative pressure. It predicts that increasing negative pressure at temperatures below about 262 K eventually results in homogeneous ice nucleation while at warmer temperature homogeneous cavitation, i. e. bubble nucleation, dominates. Negative pressure occurs locally and briefly when water is stretched due to mechanical shock, sonic waves, or fragmentation. The occurrence of such transient negative pressure should suffice to trigger homogeneous ice nucleation at large supercooling in the absence of ice-nucleating surfaces. In addition, negative pressure can act together with ice-inducing surfaces to enhance their intrinsic ice nucleation efficiency. Dynamic ice nucleation can be used to improve properties and uniformity of frozen products by applying ultrasonic fields and might also be relevant for the freezing of large drops in rainclouds.

DETECTIONS OF TRANS-NEPTUNIAN ICE IN PROTOPLANETARY DISKS

Energy Technology Data Exchange (ETDEWEB)

McClure, M. K.; Calvet, N.; Bergin, E.; Cleeves, L. I. [Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Bldg., Ann Arbor, MI 48109 (United States); Espaillat, C. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); D' Alessio, P. [Centro de Radioastronomía y Astrofísica, Universidad NacionalAUtónoma de México, 58089 Morelia, Michoacán (Mexico); Watson, D. M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Manoj, P. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Sargent, B., E-mail: melisma@umich.edu, E-mail: ncalvet@umich.edu, E-mail: ebergin@umich.edu, E-mail: cleeves@umich.edu, E-mail: cce@bu.edu, E-mail: p.dalessio@crya.unam.mx, E-mail: dmw@pas.rochester.edu, E-mail: manoj.puravankara@tifr.res.in, E-mail: baspci@rit.edu [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)

2015-02-01

We present Herschel Space Observatory PACS spectra of T Tauri stars, in which we detect amorphous and crystalline water ice features. Using irradiated accretion disk models, we determine the disk structure and ice abundance in each of the systems. Combining a model-independent comparison of the ice feature strength and disk size with a detailed analysis of the model ice location, we estimate that the ice emitting region is at disk radii >30 AU, consistent with a proto-Kuiper belt. Vertically, the ice emits most below the photodesorption zone, consistent with Herschel observations of cold water vapor. The presence of crystallized water ice at a disk location (1) colder than its crystallization temperature and (2) where it should have been re-amorphized in ∼1 Myr suggests that localized generation is occurring; the most likely cause appears to be micrometeorite impact or planetesimal collisions. Based on simple tests with UV models and different ice distributions, we suggest that the SED shape from 20 to 50 μm may probe the location of the water ice snowline in the disk upper layers. This project represents one of the first extra-solar probes of the spatial structure of the cometary ice reservoir thought to deliver water to terrestrial planets.

Turbulent heat transfer as a control of platelet ice growth in supercooled under-ice ocean boundary layers

Science.gov (United States)

McPhee, Miles G.; Stevens, Craig L.; Smith, Inga J.; Robinson, Natalie J.

2016-04-01

Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, Antarctica, identified processes that influence growth at the interface of an ice surface in contact with supercooled seawater. The data show that turbulent heat exchange at the ocean-ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. Platelet growth in supercooled water under thick ice appears to be rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the underside of ice shelves and sea ice in the vicinity of ice shelves.

Near-Surface Profiles of Water Stable Isotope Components and Indicated Transitional History of Ice-Wedge Polygons Near Barrow

Science.gov (United States)

Iwahana, G.; Wilson, C.; Newman, B. D.; Heikoop, J. M.; Busey, R.

2017-12-01

Wetlands associated with ice-wedge polygons are commonly distributed across the Arctic Coastal Plain of northern Alaska, a region underlain by continuous permafrost. Micro-topography of the ice-wedge polygons controls local hydrology, and the micro-topography could be altered due to factors such like surface vegetation, wetness, freeze-thaw cycles, and permafrost degradation/aggradation under climate change. Understanding status of the wetlands in the near future is important because it determines biogeochemical cycle, which drives release of greenhouse gases from the ground. However, transitional regime of the ice-wedge polygons under the changing climate is not fully understood. In this study, we analyzed geochemistry of water extracted from frozen soil cores sampled down to about 1m depth in 2014 March at NGEE-Arctic sites in the Barrow Environmental Observatory. The cores were sampled from troughs/rims/centers of five different low-centered or flat-centered polygons. The frozen cores are divided into 5-10cm cores for each location, thawed in sealed plastic bags, and then extracted water was stored in vials. Comparison between the profiles of geochemistry indicated connection of soil water in the active layer at different location in a polygon, while it revealed that distinctly different water has been stored in permafrost layer at troughs/rims/centers of some polygons. Profiles of volumetric water content (VWC) showed clear signals of freeze-up desiccation in the middle of saturated active layers as low VWC anomalies at most sampling points. Water in the active layer and near-surface permafrost was classified into four categories: ice wedge / fresh meteoric / transitional / highly fractionated water. The overall results suggested prolonged separation of water in the active layer at the center of low-centered polygons without lateral connection in water path in the past.

The Antartic Ice Borehole Probe

Science.gov (United States)

Behar, A.; Carsey, F.; Lane, A.; Engelhardt, H.

2000-01-01

The Antartic Ice Borehole Probe mission is a glaciological investigation, scheduled for November 2000-2001, that will place a probe in a hot-water drilled hole in the West Antartic ice sheet. The objectives of the probe are to observe ice-bed interactions with a downward looking camera, and ice inclusions and structure, including hypothesized ice accretion, with a side-looking camera.

Ice-surface adsorption enhanced colligative effect of antifreeze proteins in ice growth inhibition

Science.gov (United States)

Mao, Yougang; Ba, Yong

2006-09-01

This Communication describes a mechanism to explain antifreeze protein's function to inhibit the growth of ice crystals. We propose that the adsorption of antifreeze protein (AFP) molecules on an ice surface induces a dense AFP-water layer, which can significantly decrease the mole fraction of the interfacial water and, thus, lower the temperature for a seed ice crystal to grow in a super-cooled AFP solution. This mechanism can also explain the nearly unchanged melting point for the ice crystal due to the AFP's ice-surface adsorption. A mathematical model combining the Langmuir theory of adsorption and the colligative effect of thermodynamics has been proposed to find the equilibrium constants of the ice-surface adsorptions, and the interfacial concentrations of AFPs through fitting the theoretical curves to the experimental thermal hysteresis data. This model has been demonstrated by using the experimental data of serial size-mutated beetle Tenebrio molitor (Tm) AFPs. It was found that the AFP's ice-surface adsorptions could increase the interfacial AFP's concentrations by 3 to 4 orders compared with those in the bulk AFP solutions.

Thermodynamic and Dynamic Aspects of Ice Nucleation

Science.gov (United States)

Barahona, Donifan

2018-01-01

It is known that ice nucleating particles (INP) immersed within supercooled droplets promote the formation of ice. Common theoretical models used to represent this process assume that the immersed particle lowers the work of ice nucleation without significantly affecting the dynamics of water in the vicinity of the particle. This is contrary to evidence showing that immersed surfaces significantly affect the viscosity and diffusivity of vicinal water. To study how this may affect ice formation this work introduces a model linking the ice nucleation rate to the modification of the dynamics and thermodynamics of vicinal water by immersed particles. It is shown that INP that significantly reduce the work of ice nucleation also pose strong limitations to the growth of the nascent ice germs. This leads to the onset of a new ice nucleation regime, called spinodal ice nucleation, where the dynamics of ice germ growth instead of the ice germ size determines the nucleation rate. Nucleation in this regime is characterized by an enhanced sensitivity to particle area and cooling rate. Comparison of the predicted ice nucleation rate against experimental measurements for a diverse set of species relevant to cloud formation suggests that spinodal ice nucleation may be common in nature.

Effects of sea-ice light attenuation and CDOM absorption in the water below the Eurasian sector of central Arctic Ocean (> 880N)

DEFF Research Database (Denmark)

Lund-Hansen, Lars Chresten; Markager, Stiig; Hancke, Kasper

2015-01-01

This is a study of the optical, physical and biological parameters of sea ice and the water below it at stations (n=25) in the central (>88°N) Eurasian sector of the Arctic Ocean during the summer 2012 record low sea-ice minimum extent. Results show that photosynthetically active radiation (PAR......) transmittance of the ice was low (0.09) and apparently related to a high degree of backscattering by air-filled brine channels left by brine draining. The under-ice PAR was also low (8.4±4.5 SD µmol photons m−2 s−1) and partly related to the low transmittance. There were no significant differences in multi......-year and first-year PAR transmittances. In spite of this low under-ice PAR, only 3% of the transmitted PAR through the ice was absorbed by phytoplankton in the water. On average, chlorophyll-a concentrations were low (0.34±0.69 SD mg chl-a m−3) in the water compared to the high (a375=0.52 m−1) coloured dissolved...

Development of a Capacitive Ice Sensor to Measure Ice Growth in Real Time

Directory of Open Access Journals (Sweden)

Xiang Zhi

2015-03-01

Full Text Available This paper presents the development of the capacitive sensor to measure the growth of ice on a fuel pipe surface in real time. The ice sensor consists of pairs of electrodes to detect the change in capacitance and a thermocouple temperature sensor to examine the ice formation situation. In addition, an environmental chamber was specially designed to control the humidity and temperature to simulate the ice formation conditions. From the humidity, a water film is formed on the ice sensor, which results in an increase in capacitance. Ice nucleation occurs, followed by the rapid formation of frost ice that decreases the capacitance suddenly. The capacitance is saturated. The developed ice sensor explains the ice growth providing information about the icing temperature in real time.

Development of a capacitive ice sensor to measure ice growth in real time.

Science.gov (United States)

Zhi, Xiang; Cho, Hyo Chang; Wang, Bo; Ahn, Cheol Hee; Moon, Hyeong Soon; Go, Jeung Sang

2015-03-19

This paper presents the development of the capacitive sensor to measure the growth of ice on a fuel pipe surface in real time. The ice sensor consists of pairs of electrodes to detect the change in capacitance and a thermocouple temperature sensor to examine the ice formation situation. In addition, an environmental chamber was specially designed to control the humidity and temperature to simulate the ice formation conditions. From the humidity, a water film is formed on the ice sensor, which results in an increase in capacitance. Ice nucleation occurs, followed by the rapid formation of frost ice that decreases the capacitance suddenly. The capacitance is saturated. The developed ice sensor explains the ice growth providing information about the icing temperature in real time.

Water, ice, and meteorological measurements at South Cascade Glacier, Washington, balance year 2002

Science.gov (United States)

Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

2004-01-01

Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass balance quantities for balance year 2002. The 2002 glacier-average maximum winter snow balance was 4.02 meters, the second largest since 1959. The 2002 glacier summer, net, and annual (water year) balances were -3.47, 0.55, and 0.54 meters, respectively. The area of the glacier near the end of the balance year was 1.92 square kilometers, and the equilibrium-line altitude and the accumulation area ratio were 1,820 meters and 0.84, respectively. During September 20, 2001 to September 13, 2002, the terminus retreated 4 meters, and computed average ice speeds in the ablation area ranged from 7.8 to 20.7 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin were measured during part of the 2002 water year. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed and incoming solar radiation were measured at selected locations near the glacier.

Ecology of southern ocean pack ice.

Science.gov (United States)

Brierley, Andrew S; Thomas, David N

2002-01-01

Around Antarctica the annual five-fold growth and decay of sea ice is the most prominent physical process and has a profound impact on marine life there. In winter the pack ice canopy extends to cover almost 20 million square kilometres--some 8% of the southern hemisphere and an area larger than the Antarctic continent itself (13.2 million square kilometres)--and is one of the largest, most dynamic ecosystems on earth. Biological activity is associated with all physical components of the sea-ice system: the sea-ice surface; the internal sea-ice matrix and brine channel system; the underside of sea ice and the waters in the vicinity of sea ice that are modified by the presence of sea ice. Microbial and microalgal communities proliferate on and within sea ice and are grazed by a wide range of proto- and macrozooplankton that inhabit the sea ice in large concentrations. Grazing organisms also exploit biogenic material released from the sea ice at ice break-up or melt. Although rates of primary production in the underlying water column are often low because of shading by sea-ice cover, sea ice itself forms a substratum that provides standing stocks of bacteria, algae and grazers significantly higher than those in ice-free areas. Decay of sea ice in summer releases particulate and dissolved organic matter to the water column, playing a major role in biogeochemical cycling as well as seeding water column phytoplankton blooms. Numerous zooplankton species graze sea-ice algae, benefiting additionally because the overlying sea-ice ceiling provides a refuge from surface predators. Sea ice is an important nursery habitat for Antarctic krill, the pivotal species in the Southern Ocean marine ecosystem. Some deep-water fish migrate to shallow depths beneath sea ice to exploit the elevated concentrations of some zooplankton there. The increased secondary production associated with pack ice and the sea-ice edge is exploited by many higher predators, with seals, seabirds and whales

Duality of Ross Ice Shelf systems: crustal boundary, ice sheet processes and ocean circulation from ROSETTA-Ice surveys

Science.gov (United States)

Tinto, K. J.; Siddoway, C. S.; Padman, L.; Fricker, H. A.; Das, I.; Porter, D. F.; Springer, S. R.; Siegfried, M. R.; Caratori Tontini, F.; Bell, R. E.

2017-12-01

Bathymetry beneath Antarctic ice shelves controls sub-ice-shelf ocean circulation and has a major influence on the stability and dynamics of the ice sheets. Beneath the Ross Ice Shelf, the sea-floor bathymetry is a product of both tectonics and glacial processes, and is influenced by the processes it controls. New aerogeophysical surveys have revealed a fundamental crustal boundary bisecting the Ross Ice Shelf and imparting a duality to the Ross Ice Shelf systems, encompassing bathymetry, ocean circulation and ice flow history. The ROSETTA-Ice surveys were designed to increase the resolution of Ross Ice Shelf mapping from the 55 km RIGGS survey of the 1970s to a 10 km survey grid, flown over three years from New York Air National Guard LC130s. Radar, LiDAR, gravity and magnetic instruments provide a top to bottom profile of the ice shelf and the underlying seafloor, with 20 km resolution achieved in the first two survey seasons (2015 and 2016). ALAMO ocean-profiling floats deployed in the 2016 season are measuring the temperature and salinity of water entering and exiting the sub-ice water cavity. A significant east-west contrast in the character of the magnetic and gravity fields reveals that the lithospheric boundary between East and West Antarctica exists not at the base of the Transantarctic Mountains (TAM), as previously thought, but 300 km further east. The newly-identified boundary spatially coincides with the southward extension of the Central High, a rib of shallow basement identified in the Ross Sea. The East Antarctic side is characterized by lower amplitude magnetic anomalies and denser TAM-type lithosphere compared to the West Antarctic side. The crustal structure imparts a fundamental duality on the overlying ice and ocean, with deeper bathymetry and thinner ice on the East Antarctic side creating a larger sub-ice cavity for ocean circulation. The West Antarctic side has a shallower seabed, more restricted ocean access and a more complex history of

Wave excited motion of a body floating on water confined between two semi-infinite ice sheets

Science.gov (United States)

Ren, K.; Wu, G. X.; Thomas, G. A.

2016-12-01

The wave excited motion of a body floating on water confined between two semi-infinite ice sheets is investigated. The ice sheet is treated as an elastic thin plate and water is treated as an ideal and incompressible fluid. The linearized velocity potential theory is adopted in the frequency domain and problems are solved by the method of matched eigenfunctions expansion. The fluid domain is divided into sub-regions and in each sub-region the velocity potential is expanded into a series of eigenfunctions satisfying the governing equation and the boundary conditions on horizontal planes including the free surface and ice sheets. Matching is conducted at the interfaces of two neighbouring regions to ensure the continuity of the pressure and velocity, and the unknown coefficients in the expressions are obtained as a result. The behaviour of the added mass and damping coefficients of the floating body with the effect of the ice sheets and the excitation force are analysed. They are found to vary oscillatorily with the wave number, which is different from that for a floating body in the open sea. The motion of the body confined between ice sheets is investigated, in particular its resonant behaviour with extremely large motion found to be possible under certain conditions. Standing waves within the polynya are also observed.

Major new sources of biological ice nuclei

Science.gov (United States)

Moffett, B. F.; Hill, T.; Henderson-Begg, S. K.

2009-12-01

Almost all research on biological ice nucleation has focussed on a limited number of bacteria. Here we characterise several major new sources of biogenic ice nuclei. These include mosses, hornworts, liverworts and cyanobacteria. Ice nucleation in the eukaryotic bryophytes appears to be ubiquitous. The temperature at which these organisms nucleate is that at which the difference in vapour pressure over ice and water is at or close to its maximum. At these temperatures (-8 to -18 degrees C) ice will grow at the expense of supercooled water. These organisms are dependent for their water on occult precipitation - fog, dew and cloudwater which by its nature is not collected in conventional rain gauges. Therefore we suggest that these organism produce ice nuclei as a water harvesting mechanism. Since the same mechanism would also drive the Bergeron-Findeisen process, and as moss is known to become airborne, these nuclei may have a role in the initiation of precipitation. The properties of these ice nuclei are very different from the well characterised bacterial nuclei. We will also present DNA sequence data showing that, although related, the proteins responsible are only very distantly related to the classical bacterial ice nuclei.

Ikaite crystals in melting sea ice - implications for pCO2 and pH levels in Arctic surface waters

Science.gov (United States)

Rysgaard, S.; Glud, R. N.; Lennert, K.; Cooper, M.; Halden, N.; Leakey, R. J. G.; Hawthorne, F. C.; Barber, D.

2012-08-01

A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5-1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m-2 sea ice d-1 or to 3.3 ton km-2 ice floe week-1. This is markedly higher than the estimated primary production within the ice floe of 0.3-1.3 mmol m-2 sea ice d-1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

McCall Glacier record of Arctic climate change: Interpreting a northern Alaska ice core with regional water isotopes

Science.gov (United States)

Klein, E. S.; Nolan, M.; McConnell, J.; Sigl, M.; Cherry, J.; Young, J.; Welker, J. M.

2016-01-01

We explored modern precipitation and ice core isotope ratios to better understand both modern and paleo climate in the Arctic. Paleoclimate reconstructions require an understanding of how modern synoptic climate influences proxies used in those reconstructions, such as water isotopes. Therefore we measured periodic precipitation samples at Toolik Lake Field Station (Toolik) in the northern foothills of the Brooks Range in the Alaskan Arctic to determine δ18O and δ2H. We applied this multi-decadal local precipitation δ18O/temperature regression to ∼65 years of McCall Glacier (also in the Brooks Range) ice core isotope measurements and found an increase in reconstructed temperatures over the late-20th and early-21st centuries. We also show that the McCall Glacier δ18O isotope record is negatively correlated with the winter bidecadal North Pacific Index (NPI) climate oscillation. McCall Glacier deuterium excess (d-excess, δ2H - 8*δ18O) values display a bidecadal periodicity coherent with the NPI and suggest shifts from more southwestern Bering Sea moisture sources with less sea ice (lower d-excess values) to more northern Arctic Ocean moisture sources with more sea ice (higher d-excess values). Northern ice covered Arctic Ocean McCall Glacier moisture sources are associated with weak Aleutian Low (AL) circulation patterns and the southern moisture sources with strong AL patterns. Ice core d-excess values significantly decrease over the record, coincident with warmer temperatures and a significant reduction in Alaska sea ice concentration, which suggests that ice free northern ocean waters are increasingly serving as terrestrial precipitation moisture sources; a concept recently proposed by modeling studies and also present in Greenland ice core d-excess values during previous transitions to warm periods. This study also shows the efficacy and importance of using ice cores from Arctic valley glaciers in paleoclimate reconstructions.

Determining ice water content from 2D crystal images in convective cloud systems

Science.gov (United States)

Leroy, Delphine; Coutris, Pierre; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter

2016-04-01

Cloud microphysical in-situ instrumentation measures bulk parameters like total water content (TWC) and/or derives particle size distributions (PSD) (utilizing optical spectrometers and optical array probes (OAP)). The goal of this work is to introduce a comprehensive methodology to compute TWC from OAP measurements, based on the dataset collected during recent HAIC (High Altitude Ice Crystals)/HIWC (High Ice Water Content) field campaigns. Indeed, the HAIC/HIWC field campaigns in Darwin (2014) and Cayenne (2015) provide a unique opportunity to explore the complex relationship between cloud particle mass and size in ice crystal environments. Numerous mesoscale convective systems (MCSs) were sampled with the French Falcon 20 research aircraft at different temperature levels from -10°C up to 50°C. The aircraft instrumentation included an IKP-2 (isokinetic probe) to get reliable measurements of TWC and the optical array probes 2D-S and PIP recording images over the entire ice crystal size range. Based on the known principle relating crystal mass and size with a power law (m=α•Dβ), Fontaine et al. (2014) performed extended 3D crystal simulations and thereby demonstrated that it is possible to estimate the value of the exponent β from OAP data, by analyzing the surface-size relationship for the 2D images as a function of time. Leroy et al. (2015) proposed an extended version of this method that produces estimates of β from the analysis of both the surface-size and perimeter-size relationships. Knowing the value of β, α then is deduced from the simultaneous IKP-2 TWC measurements for the entire HAIC/HIWC dataset. The statistical analysis of α and β values for the HAIC/HIWC dataset firstly shows that α is closely linked to β and that this link changes with temperature. From these trends, a generalized parameterization for α is proposed. Finally, the comparison with the initial IKP-2 measurements demonstrates that the method is able to predict TWC values

Parameterizing Size Distribution in Ice Clouds

Energy Technology Data Exchange (ETDEWEB)

DeSlover, Daniel; Mitchell, David L.

2009-09-25

PARAMETERIZING SIZE DISTRIBUTIONS IN ICE CLOUDS David L. Mitchell and Daniel H. DeSlover ABSTRACT An outstanding problem that contributes considerable uncertainty to Global Climate Model (GCM) predictions of future climate is the characterization of ice particle sizes in cirrus clouds. Recent parameterizations of ice cloud effective diameter differ by a factor of three, which, for overcast conditions, often translate to changes in outgoing longwave radiation (OLR) of 55 W m-2 or more. Much of this uncertainty in cirrus particle sizes is related to the problem of ice particle shattering during in situ sampling of the ice particle size distribution (PSD). Ice particles often shatter into many smaller ice fragments upon collision with the rim of the probe inlet tube. These small ice artifacts are counted as real ice crystals, resulting in anomalously high concentrations of small ice crystals (D < 100 µm) and underestimates of the mean and effective size of the PSD. Half of the cirrus cloud optical depth calculated from these in situ measurements can be due to this shattering phenomenon. Another challenge is the determination of ice and liquid water amounts in mixed phase clouds. Mixed phase clouds in the Arctic contain mostly liquid water, and the presence of ice is important for determining their lifecycle. Colder high clouds between -20 and -36 oC may also be mixed phase but in this case their condensate is mostly ice with low levels of liquid water. Rather than affecting their lifecycle, the presence of liquid dramatically affects the cloud optical properties, which affects cloud-climate feedback processes in GCMs. This project has made advancements in solving both of these problems. Regarding the first problem, PSD in ice clouds are uncertain due to the inability to reliably measure the concentrations of the smallest crystals (D < 100 µm), known as the “small mode”. Rather than using in situ probe measurements aboard aircraft, we employed a treatment of ice

Benchmarking a first-principles thermal neutron scattering law for water ice with a diffusion experiment

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Holmes Jesse

2017-01-01

Full Text Available The neutron scattering properties of water ice are of interest to the nuclear criticality safety community for the transport and storage of nuclear materials in cold environments. The common hexagonal phase ice Ih has locally ordered, but globally disordered, H2O molecular orientations. A 96-molecule supercell is modeled using the VASP ab initio density functional theory code and PHONON lattice dynamics code to calculate the phonon vibrational spectra of H and O in ice Ih. These spectra are supplied to the LEAPR module of the NJOY2012 nuclear data processing code to generate thermal neutron scattering laws for H and O in ice Ih in the incoherent approximation. The predicted vibrational spectra are optimized to be representative of the globally averaged ice Ih structure by comparing theoretically calculated and experimentally measured total cross sections and inelastic neutron scattering spectra. The resulting scattering kernel is then supplied to the MC21 Monte Carlo transport code to calculate time eigenvalues for the fundamental mode decay in ice cylinders at various temperatures. Results are compared to experimental flux decay measurements for a pulsed-neutron die-away diffusion benchmark.

Cultivation of Nannochloropsis sp. in brackish groundwater supplemented with municipal wastewater as a nutrient source

Directory of Open Access Journals (Sweden)

Louise Lins de Sousa

2014-04-01

Full Text Available The aim of this work was to study growth potential of the green microalgae Nannochloropsis sp. using brackish groundwater from a well in the semi-arid northeast region of Brazil as culture medium. The medium was supplemented with (% 19.4, 22.0, 44.0 and 50.0% of municipal wastewater after UASB treatment as a low-cost nutrient source. The results showed that the culture tested was capable of growing in the brackish groundwater even at salinity levels as low as 2 ppt. Furthermore it was shown that municipal wastewater could be used as a sole nutrient source for Nannochloropsis sp.

Interannual observations and quantification of summertime H2O ice deposition on the Martian CO2 ice south polar cap

Science.gov (United States)

Brown, Adrian J.; Piqueux, Sylvain; Titus, Timothy N.

2014-01-01

The spectral signature of water ice was observed on Martian south polar cap in 2004 by the Observatoire pour l'Mineralogie, l'Eau les Glaces et l'Activite (OMEGA) ( Bibring et al., 2004). Three years later, the OMEGA instrument was used to discover water ice deposited during southern summer on the polar cap ( Langevin et al., 2007). However, temporal and spatial variations of these water ice signatures have remained unexplored, and the origins of these water deposits remains an important scientific question. To investigate this question, we have used observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter (MRO) spacecraft of the southern cap during austral summer over four Martian years to search for variations in the amount of water ice. We report below that for each year we have observed the cap, the magnitude of the H2O ice signature on the southern cap has risen steadily throughout summer, particularly on the west end of the cap. The spatial extent of deposition is in disagreement with the current best simulations of deposition of water ice on the south polar cap (Montmessin et al., 2007). This increase in water ice signatures is most likely caused by deposition of atmospheric H2O ice and a set of unusual conditions makes the quantification of this transport flux using CRISM close to ideal. We calculate a ‘minimum apparent‘ amount of deposition corresponding to a thin H2O ice layer of 0.2 mm (with 70% porosity). This amount of H2O ice deposition is 0.6–6% of the total Martian atmospheric water budget. We compare our ‘minimum apparent’ quantification with previous estimates. This deposition process may also have implications for the formation and stability of the southern CO2 ice cap, and therefore play a significant role in the climate budget of modern day Mars.

Effects of cadmium and lead upon the indigenous heterotrophic microflora in the aqueous environment of the brackish estuary-water of the river Weser

Energy Technology Data Exchange (ETDEWEB)

Thormann, D

1975-01-01

In agar media (10% salinity) containing Cd or Pb bacterial numbers were progressively reduced at 0.5 to 400 ppM Cd and at 100 to 400 ppM Pb. Only a few bacteria were able to form colonies at the highest concentrations. Lower salinity and low peptone-yeast-extract-concentrations of the medium increased the toxicity of Pb. The appearance of several brown-black pigmented colonies on the plates containing more than 200 ppM Pb was observed, but no dark pigment was noted when the same bacteria were grown in the absence of Pb. Different concentrations of Cd or Pb were added to water samples (as batch cultures) of the Weser Estuary (West Germany). The development of the indigenous microbial population was observed by subsequent counting of the viable heterotrophic bacteria on agar media. Cd was more toxic than Pb; there were differences in the kind of toxicity. The dissolved concentrations of Cd and Pb in the batch cultures were analyzed by atomic absorption. Cd dissolved considerably better than Pb in brackish water. Cd- and Pb-sensitive bacteria were isolated by a replica plating technique to carry out subsequent experiments on the microbial uptake of heavy metals. The most sensitive bacteria were growth-inhibited at 0.1 ppM Cd and Pb. Arthrobacter marinus is mentioned.

A summary review of modelling oil in ice

International Nuclear Information System (INIS)

Khelifa, A.

2009-01-01

The increase of maritime shipping and industrial developments in the Arctic increases the risk for potential oil spills in ice. Such spills are difficult to track, may contaminate vast areas after the melting season and may take months to clean. As such, there is a need for robust spill models that can predict the trajectory and fate of soil spilled in ice. This paper summarized the results obtained from a recent review on the state of knowledge on modelling approaches developed during the last 4 decades to predict transport and weathering of oil spilled in ice-infested waters. It showed that modelling oil spills on ice is much less developed than oil-spill modelling in open water. There appears to be a lag between the advancement of understanding the fate and behaviour and the integration of the results into operational oil-spill models. The most widely used method consists of adapting existing open-water oil spill models to ice-infested waters by introducing a correction factor proportional to ice coverage to key processes controlling the transport and weathering of oil in ice. Few models use a quadratic scaling factor. As such most existing oil spill models are inadequate to accurately reproduce field observations related to oil spills in ice. Existing data shows that variations of evaporation and emulsification rates are not linearly correlated with the percentage of ice coverage. The decrease in these rates is a function of the ice coverage, the type of ice, and varies with time after the spill. The study found that future models for oil spill in ice-infested waters should be combined with robust ice models coupled with atmospheric models, circulation models and wave models which includes the effect of ice. The dynamic approach was shown to adapt well to coupling with ice models. 81 refs., 2 tabs.