Iceberg Melting and Climate Change in NW Atlantic Waters

Climate change is predicted to cause increases in sea surface temperature (SST), as well as decreases in sea-ice cover, wind and current velocities. These changes will have a marked effect on iceberg melting in the shipping lanes off Newfoundland and Labrador, Canada. Icebergs that today can cross from northern Labrador to Newfoundland without melting will in the future have to be much larger to survive the transit. For example, icebergs at N Labrador in December of 2016 that are smaller than 156 m will melt before reaching 48N, but in year 2100 the length increases to 228 m. In addition, if future iceberg size distributions off Labrador are the same as today, icebergs will experience roughly 50% reductions in numbers in the NW Atlantic shipping lanes by year 2100. The increased melting rates are due to, in order of importance, increased sea-surface temperatures (responsible for 66% of the increase in the minimum transit size), decreasing current velocities (31%), and decreasing sea-ice cover (3%). Decreasing sea-ice tends to increase wave heights as well as accelerate the effects of wave erosion; however, for the areas studied the wave height is predicted to decrease moderately in year 2100, by a maximum of about 10% in December

Osmotic Coefficients, Solubilities, and Deliquescence Relations in Mixed Aqueous Salt Solutions at Elevated Temperature

While thermodynamic properties of pure aqueous electrolytes are relatively well known at ambient temperature, there are far fewer data for binary systems extending to elevated temperatures and high concentrations. There is no general theoretically sound basis for prediction of the temperature dependence of ionic activities, and consequently temperature extrapolations based on ambient temperature data and empirical equations are uncertain and require empirical verification. Thermodynamic properties of mixed brines in a wide range of concentrations would enhance the understanding and precise modeling of the effects of deliquescence of initially dry solids in humid air in geological environments and in modeling the composition of waters during heating, cooling, evaporation or condensation processes. These conditions are of interest in the analysis of waters on metal surfaces at the proposed radioactive waste repository at Yucca Mountain, Nevada. The results obtained in this project will be useful for modeling the long-term evolution of the chemical environment, and this in turn is useful for the analysis of the corrosion of waste packages. In particular, there are few reliable experimental data available on the relationship between relative humidity and composition that reveals the eutonic points of the mixtures and the mixture deliquescence RH. The deliquescence RH for multicomponent mixtures is lower than that of pure component or binary solutions, but is not easy to predict quantitatively since the solutions are highly nonideal. In this work we used the ORNL low-temperature and high-temperature isopiestic facilities, capable of precise measurements of vapor pressure between ambient temperature and 250 C for determination of not only osmotic coefficients, but also solubilities and deliquescence points of aqueous mixed solutions in a range of temperatures. In addition to standard solutions of CaCl{sub 2}, LiCl, and NaCl used as references, precise direct-pressure measurements were also made at elevated temperatures. The project included multicomponent mixtures useful for verification of models, and a set of binary solutions with common ions (such as KNO{sub 3} + NaNO{sub 3}, KNO{sub 3} + Ca(NO{sub 3}){sub 2}, NaNO{sub 3} + Na{sub 2}SO{sub 4}, and KNO{sub 3} + K{sub 2}SO{sub 4}) needed for determination of the mixing parameters in the Pitzer ion-interaction model for mixtures. The results are compared with existing experimental results and model predictions

The Partitioning of Acetic, Formic, and Phosphoric Acids Between Liquid Water and Steam

The chemical carryover of impurities and treatment chemicals from the boiler to the steam phase, and ultimately to the low-pressure turbine and condenser, can be quantified based on laboratory experiments preformed over ranges of temperature, pH, and composition. The two major assumptions are that thermodynamic equilibrium is maintained and no deposition, adsorption or decomposition occurs. The most recent results on acetic, formic and phosphoric acids are presented with consideration of the effects of hydrolysis and dimerization reactions. Complications arising from thermal decomposition of the organic acids are discussed. The partitioning constants for these acids and other solutes measured in this program have been incorporated into a simple thermodynamic computer code that calculates the effect of chemical and mechanical carryover on the composition of the condensate formed to varying extents in the water/steam cycle

Disentangling historical relationships within Poeciliidae (Teleostei: Cyprinodontiformes) using ultraconserved elements

Poeciliids (Cyprinodontiformes: Poeciliidae), commonly known as livebearers, are popular fishes in the aquarium trade (e.g., guppies, mollies, swordtails) that are widely distributed in the Americas, with 274 valid species in 27 genera. This group has undergone various taxonomic changes recently, spurred by investigations using traditional genetic markers. Here we used over 1,000 ultraconserved loci to infer the relationships within Poeciliidae in the first attempt at understanding their diversification based on genome-scale data. We explore gene tree discordance and investigate potential incongruence between concatenation and coalescent inference methods. Our aim is to examine the influence of incomplete lineage sorting and reticulate evolution on the poeciliids’ evolutionary history and how these factors contribute to the observed gene tree discordace. Our concatenated and coalescent phylogenomic inferences recovered four major clades within Poeciliidae. Most supra-generic level relationships we inferred were congruent with previous molecular studies, but we found some disagreements; the Middle American taxa Phallichthys and Poecilia (Mollienesia) were recovered as non-monophyletic, and unlike other recent molecular studies, we recovered Brachyrhaphis as monophyletic. Our study is the first to provide signatures of reticulate evolution in Poeciliidae at the family level; however, continued finer-scale investigations are needed to understand the complex evolutionary history of the family along with a much-needed taxonomic re-evaluation

Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Ipsilateral exophthalmos in subfrontal epidural hematomas

✓ Four cases of subfrontal epidural hematoma with progressive ipsilateral exophthalmos are described, and the pathogenesis discussed.</jats:p