Games | The Hydrosphere The layer of water enveloping the earth is known as the hydrosphere. It comprises of all the physical forms of water. (Liquid,solid,gas) Water on earth is 97.5% saltwater, and 2.5% is freshwater, 79% of that is frozen and 21% is in lakes and rivers. 20% of the worlds freshwater is in Siberia, Lake Baikal. Watershed A territory of land where lakes and rivers empty into the same body of water. The boundaries are determined by the high ground that surrounds the area. The flow of water is determined by - Topography - Slope, shape and terrain - Geology - Type, depth, and structure of the rock - Climate - Rain, snowfall,winds,and temperature. - Vegetation - Density, and diversity. - Agricultural, industrial and urban development. Subwater sheds 3 main ones - Hudson Bay - Ungava Bay - St. Lawrence River Oceans Factors affecting water temperature Season:oceans lose some heat during the winter Latitude:surface temperatures can reach 25-28࿁C near the equator, and 12-17 ℃ in temperate zones. Average salinity in oceans is around 3.4% to 3.7% At the poles it 3%, and at the Red Sea its 4% Temperate Zones Depth : - Sunlight warms up the upper layer. - After 200m mark, the temperature falls rapidly.(Thermocline) - Below this, the water become very cold. An ocean current consists of a surface and a subsurface current. Cold water is denser than warm water, and salt water is denser than freshwater. Thermohaline circulation transfers heat all over the world, generated by the interaction of surface and subsurface tides. 🔁 At higher latitude, water gets colder, and vice versa. Water becomes saltier if the rate of evaporation increases. Water salinity is decreasing. Cryosphere A part of the earth where the water is rock solid. A pack ice is formed on the surface of the arctic ocean in the winter, it covers 12 million km². Ice floes are smaller, free floating sheets of ice. Icebergs are large pieces of ice that have broken off of a glacier. 1/10 of them are above water. Pack ice: Pack ice and ice floes DO NOT raise the oceans’ levels since they do not add “new” water to the system It is ice floating on the oceans near the poles Made mostly of fresh water as the salt gets pushed out by the ice crystals. Pack ice forms near Russia and accumulates over the Arctic ocean. There is more pack ice during the winter than the summer. Pack ice is currency shrinking at alarming rates. Consider that it lost two million square kilometers between 1979-2005 and by 2007 it shrank by another one million square kilometers. Consequences of Pack ice melting: Decreasing in salinity of ocean water, making it less dense and therefore slowing down the thermohaline circulation. Creation of new waterways. Displacement of species and traditional hunting grounds. Decrease of albedo (reflectivity of the earth’s surface) Glaciers: A glacier is ice that forms over land from the compression of snow. Large glaciers are called ice caps or ice sheets. Glaciers too have been melting at faster rates. There is concern that water levels are rising The increase in fresh water is also decreasing the salinity of the ocean water around it. This less dense water does not sink as it normally does, thus altering ocean currents that affect many costal regions. Energy resources P166 (diagram) In Quebec we rely almost exclusively on hydraulic energy ,i.e., energy derived from moving water. Hydraulic energy converts mechanical energy into electrical energy. Although hydroelectricity does not produce much greenhouse gases, it does have a considerable environmental impact. Huge areas are flooded and rivers are diverted. Migration patterns of caribou have been changed as well as traditional hunting and fishing grounds for Natives have disappeared. Mercury has been dissolved in water reservoirs which eventually move up the food chain. Waves and ocean currents: Buoys use the movement from waves to create electricity (turbines). Underwater turbines use ocean currents. Both are very expensive and at the prototype level. Pollution and degradation: Thermal pollution is caused by the heating of water, especially around nuclear power plants. Pollution of waters can originate from two main areas: Point sources: well defined sites like chemical companies Non-point sources: not defined sites such as farming activities. The health of an aquatic system depends on: 1: temp 2: oxygenation 3: chemical composition Eutrophication: An algal bloom resulting from too much nutrient from sources such as phosphorus and nitrogen in fertilizers The bacteria consume the available oxygen thus lowering its concentration Steps of the eutrophication process: A phosphorus/nitrogen based substance washes to a nearby body of water. Algae growth increases suddenly, creating a thick carpet at the surface, blocking the sun (photosynthesis) for the other plants. (Lots of) Dead algae collects at the bottom of the body of water Bacteria decompose the dead algae at a faster rate than normal, over consuming oxygen in the process. The levels of oxygen in the water drop. Other living organisms die from lack of oxygen.