Ocean freezing

Conversely, if too much carbonate is withdrawn by tectonics, by subduction or precipitation, then the ocean freezes. Weathering ceases. Carbon dioxide precipitation stops and the gas builds up in the air until part of the ocean melts and degasses more carbon dioxide, and the world switches from total glaciation to partial glaciation. Indeed, intuitively an inorganic world might be expected to see-saw between these two states, with rare excursions into a plume-driven moist greenhouse state. 

When the Arctic Ocean freezes, the ice contains no salt. The salt stays in the surrounding water making it dense. The density causes it to sink. As it sinks and flows back south along the ocean bottom, it makes room for the water from the Gulf Stream. If the artic gets too warm, the Gulf Stream may stop flowing. This will leave Western Europe with a climate similar to Siberia. 

Water in lakes and oceans freezes from the surface downward this permits water circulation to continue under the ice so that fish can survive. 

Photoactivation analysis has also been used to determine fluoride in seawater [73]. In this method a sample and simulated seawater standards containing known amounts of fluoride are freeze-dried, and then irradiated simultaneously and identically, for 20 min, with high-energy photons. The half-life of 18F (110 min) allows sufficient time for radiochemical separation from the seawater matrix before counting. The specific activities of sample and standards being the same, the amount of fluoride in the unknown may be calculated. The limit of detection is 7 ng fluoride, and the precision is sufficient to permit detection of variations in the fluoride content of oceans. The method can be adapted for the simultaneous determination of fluorine, bromine, and iodine. 

Methane hydrates form when methane molecules become trapped within an ice lattice as water freezes. They can form in very cold conditions or under high-pressure conditions. Both of these conditions are met in deep oceans and in permafrost. In Canada, hydrates have already been found in large quantities in the Canadian Arctic. Methane hydrate has a number of remarkable properties. For example, when brought into an oxygen atmosphere, the methane fumes can be ignited, making it appear that the ice is burning ... 

The temperature at which seawater reaches its maximum density also decreases with increasing salinity. Most seawater in the ocean has a salinity between 33% and 37%. At salinities greater than 26%, the freezing point of seawater is higher than the temperature at which it reaches its maximum density. Thus, seawater never undergoes the anomalous density behavior of pure water. Instead, sea ice floats because it is mostly pure water (some pockets of brine are often occluded into the crystal structure). 

Small amounts of salt are commonly occluded in sea ice. Not all of the ions are incorporated to the same degree. This alters the ion ratios in the remaining brine, leading to deviations from the Rule of Constant Proportions during freezing. Likewise, meltwater from sea ice can contain ions in ratios that deviate from average open ocean water. 

And so it would be with lakes, streams, and oceans were it not for the anomaly and the bouyance of ice. The coldest water would continually sink to the bottom and freeze there. The ice, once formed, could not be melted, because the warmer water would stay at the surface. Year after year the ice would increase in winter and persist through the summer, until eventually all or much of the body of water, according to the locality, would be turned to ice. As it is, the temperature of the bottom of a body of fresh water cannot be below the point of maximum density on coohng further, the water rises and ice forms only on the surface. In this way the Liquid water below is protected from further cooling, and the body of water persists. In the Spring, the first warm weather melts the ice, and at the earliest possible moment all ice vanishes. 

Adding an impurity to a solvent makes its liquid phase more stable through the combined effects of boiling point elevation and freezing point depression. That s why you r irely see bodies of frozen salt water. The salt in the oceans lowers the freezing point of the water, making the liquid phase more stable and able to sustain temperatures slightly below 0°C. 

Weathering is the process by which rock is broken down into smaller and smaller particles. It involves both mechanical and chemical breakdowns. The mechanical breakdown into smaller and smaller pieces occurs as a result of exposure to freeze-thaw cycles and to the action of wind and water. Chemical breakdown occurs as a result of exposure to air and water and other chemicals that may be dissolved in water, such as acids. Weathering by exposure to atmosphere results in some of the carbon dioxide being removed from the atmosphere along with the broken-down rock and eventually washed into the ocean. 

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