Lakes frozen

Now and then, projectiles from outer space cause excitement and surprises, as in January 2000, when a meteorite impacted the frozen surface of Lake Targish in Canada. It was a new type of C-chondrite with a carbon concentration of 4-5%, and probably came from a D-type asteroid (Hiroi et al., 2001). More exact analysis of the Targish meteorite showed the presence of a series of mono- and dicarboxylic acids as well as aliphatic and aromatic hydrocarbons (Pizzarello et al., 2001). Aromatic compounds and fullerenes were detected in the insoluble fraction from the extraction this contained planetary helium and argon, i.e., the 3He/36Ar ratio was... 

O Driscoll, N.J.O, Poissant, L., Canrio, J., Lean, D.R.S. 2008. Dissolved gaseous mercury concentrations and mercury volatilization in a frozen freshwater fluvial lake. Environmental Science and... 

Uchiyama [11] applied this method to the determination of fluorescent whitening agents and alkyl benzenesulphonates and also methylene blue active substances in bottom sediment samples taken in a lake. The muds were filtered off with a suction filter and frozen until analyzed. About 20g of wet bottom mud was extracted three times with a methanol-benzene (1 1) mixture. After the solvent was evaporated using a water bath, the residue was dissolved in hot water and this solution used for analysis. Table 10.2 shows the analytical results for methylene blue active substances (MBAS), alkyl benzene-sulphonate (ABS), and fluorescent whitening agent (FWA) in bottom sediments. 

The processes of life involve both energetic and entropic factors. When we walk, run, climb, fidget, dance, or toss and turn in bed, we are doing work against physical forces. When we ice fish on a frozen lake in Minnesota, we need to generate heat to keep our body temperature constant. That heat is lost to the enviromnent (an ineffective way to heat Minnesota in the winter but it happens nonetheless). In contrast, when we synthesize DNA in the process of cell division with its precisely ordered sequence of bases or synthesize proteins with their precisely ordered sequences of amino acids, it is entropy that we must overcome, not physical forces or heat exchange. The bottom line is that we need a source of energy to five. 

The importance of melt-water to the POC load in alpine lakes is a matter of some debate. It has been argued that direct deposition and the melting of snow that falls onto the frozen surface of a lake are the chief sources of POC transport to a lake [50]. The grounds are that movement by groundwater into the lake is unlikely as POCs likely sorb to soil organic matter, and that, at least for the lake studied, most of the water input by streams does not mix with the rest of the water column before flowing out again. The transport of soil into a lake by erosion is likely not an important process under normal conditions and this is confirmed by differences in... 

Spacecraft images of icy moons, (a) Voyager 2 image of Triton, showing complex "cantaloupe" terrain and a polar cap of nitrogen ice smooth areas near the equator may be frozen lakes. 

Evaporites on Mars and Europa. The NASA s robotic explorers, Spirit and Opportunity, landed on at Mars and examined their landing sites for past environmental conditions. Kinds of minerals in a hot-spring environment and dried-up lake beds were photographed suggesting future use of ESR to date these evaporate with a portable ESR on the rover. Sulfate mineral precipitation, epsonite, MgS04 with 7 hydration water molecules in frozen ice, was studied by sampling the icy environment, especially icy fault on the surface of Europa, a satellite of Jupiter.61... 

About 97.2 percent of Earth s water is saline (salty) ocean water. Another 2.14 percent is fresh water frozen in polar ice caps and glaciers. All the remaining water, less than 1 percent of Earth s total, comprises water vapor in the atmosphere, water in the ground, and water in rivers and lakes—the fresh water we rely on in our daily lives. 

When the temperature falls below 0°C, the surface water of the lake begins to freeze. Floating ice does not easily allow this low temperature to reach the water below. Therefore, the temperature of the water inside the lake remains above the freezing point. The fishes in the lake survive even in an apparently frozen lake. 

Water is stored in a few ways. Lakes and oceans may store liquid water for weeks, months, or years. Underground aquifers can store liquid water for thousands of years. Glaciers, ice sheets, and ice caps can store frozen water for varying periods of time. 

Have you ever wondered what happens to the animals in frozen rivers and lakes during the winter Long ago, scientists used to think marine animals were able to freeze in winter and thaw in summer, but today we know this is not the case. Many fish and turtles, for example, have developed ways to avoid freezing while storing themselves over the winter in near-frozen environments. 

The fact that water molecules are usually held to each other by hydrogen bonds is responsible for the success of our planet and of life-forms themselves. Hydrogen bonding in water is the reason that frozen water is less dense than liquid water. Not only does ice float, but more importantly, floating ice permits water below the surface in ponds and lakes to remain in a liquid state during the winter and therefore allows for the continuity of life in these waters. On a more aesthetic note, hydrogen bonding is responsible for the six-sided nature of snowflakes. 

In 2004, two boys were playing on the ice of a frozen lake in Austria. There was a sudden sharp crack and the boys disappeared into the icy water. The police and ambulance service were called by some people nearby. The... 

What happens in snow, in fact, if the snow is falling, is that there will be in snow the different salts, mainly ammonium sulphate salts — and where there are temperature changes, of course there will be in the system a freezing point depression, so finally during the season everything of these particles will be collected just over the soil, down there, and now when the melting period comes, you have the shock, and the shock, especially when the snow is lying on a frozen lake, can kill all the fish population in a few days. 

Chickens with a water content of 74 percent, an initial temperature of 0°C. and a mass of about 3.4 kg are to be frozen by refrigerated air at -40°C. Using Figure 4-53, determine how long it wilt lake to reduce the inner surface temperature of chickens to -4"C. What would your answer be if the air temperature were - 62 C ... 

The pollen of many plants can be classified by genus, and sometimes by species, on the basis of such characteristics as size, shape, and surface texture, hi contrast, most spores can only be classified by higher taxonomic levels, such as family or order. Both pollen and spores are well preserved in lake sediment, peat bog, and many archaeological sites. Fossil pollen has even been identified from the bodies of extinct animals, such as mammoths discovered frozen in arctic permafrost (permanently frozen subsoil). 

Another example of where this formula comes into play involves a person standing on a frozen lake when the ice starts to crack. You may have heard that it is advisable to lie down on the surface of the ice, if you find yourself in this situation. The logic behind this can be seen in the pressure formula. By lying down on the surface of the ice, you will increase the area of your body that is in contact with the ice. Because the pressure that you exert on the surface of the ice is inversely proportional to the area of contact, you will be less likely to break through. 

Once removed from a lake, sediments should be frozen (< — 20°C) in the dark... 

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