Knowledge point: Heavy metal ion pollution in water refers to pollution caused by pollutants containing heavy metal ions entering the water body.
As an important cradle of human civilization, rivers provide multiple service functions such as irrigation, reproduction and navigation for the survival and development of humanity. After entering modern civilization, the human development of rivers has become more and more diversified, of which the construction of dams and the construction of hydroelectric power stations are a typical example, such as the famous Gezhouba Hydroelectric Power Station, the Three Hydroelectric Power Station Gorges and the Xiluodu hydroelectric power station in China. The existence of hydroelectric power stations can effectively alleviate the difficulties of electricity supply, but the establishment of hydroelectric power stations on riversinitially smooth res had various impacts on river water quality. Of course, these impacts are both good and bad.
First, let's talk about the harmful effects of the construction of hydroelectric plants on water quality. On the one hand, the water velocity in the reservoir area is low, which reduces the exchange rate of water and air interface as well as the migration and diffusion capacity of pollutants. Dissolved oxygen will be reduced, as well as the self-purification capacity of the water body. will also be reduced.
On the other hand, the water speed in the reservoir area is low and the transparency is high, which is conducive to algae photosynthesis. If the water flow contains many nutrients and the water depth is shallow, this will be the case. be easier to form eutrophication.
In addition, the water speed in the reservoir area is low and sedimentation is enhanced. CertaHeavy metal elements will be deposited upstream of the hydroelectric plant, thereby increasing heavy metal pollution. In addition, when hydropower plants release water for flushing, heavy metals adsorbed on the sediment surface will be released into the water body again, aggravating the degree of heavy metal pollution in the water.
Although the construction of hydropower plants has many negative effects on river water quality, the positive effect of the construction of hydropower plants on water quality cannot be ignored . Due to the interception of a large amount of running water by hydropower plants, the upstream sediments have been deposited to a certain extent, which in turn can gradually weaken the degree of sedimentation of water quality. water downstream. In addition, due to the low flow of the body of water upstream of the hydroelectric power station, the reproductionAlgae ion is active, the carbon dioxide produced by biological respiration and the increase in carbon dioxide at depth causes the calcium and magnesium ions present in the water to settle, thereby reducing the hardness of the water body.
In the first years after the construction of the hydroelectric plant, the negative impact of the hydroelectric plant on water quality was greater than its beneficial impact. However, as the river gradually adapts to the new ecological environment, the river gradually adapts to the new ecological environment. the water quality and ecological environment of the river will gradually recover and form a new stable ecosystem.
Author: Mr. Tadpole
This work is an original work of "Popular Science in China-One-Point Scientific Principles"
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Firepower:
Advantages: The technology is mature and the current cost is low. Low geographic environment requirements.
Disadvantages: high pollution, poor prospects for sustainable development. It consumes a lot of energy and has low efficiency.
Hydraulic power:
Advantages: long history, low subsequent costs. No pollution, renewable water energy, large total water energy reserves.
Disadvantages: large capital investments and high requirements for geographical environment. For example, southwest China is extremely rich in water resources, but the natural environment is harsh and construction is difficult, making its use impossible. them.
Detailed information:
The production of electricity is the use of devices of electricity generation to convert water energy, energyThermal energy from fossil fuels, nuclear energy, solar energy, wind energy, geothermal energy and ocean energy can convert many types of energy into electrical energy. By the end of the 20th century, most electricity generation used the method of burning fossil fuels. However, fossil fuel resources are not abundant and are becoming increasingly depleted. At present, humans are gradually using renewable energies (hydraulic energy, solar energy, energy). wind energy, geothermal energy, marine energy, etc.) to produce electricity.
The basic principle of hydroelectricity is to use the difference in water level to produce electricity with a hydroelectric generator, that is, the potential energy of the water is converted into mechanical energy of the water wheel, and then into mechanical energy. mechanical energy isused to drive the generator to obtain electricity. Scientists take advantage of the natural conditions of water level difference, effectively use fluid engineering and mechanical physics, and carefully combine them to achieve the highest power generation capacity, so that people can use an electricity cheap and pollution-free.
Thermal power generation generally refers to the use of thermal energy generated when fuels such as oil, coal and natural gas are burned to heat water, transforming the water into water vapor at high temperature and high pressure, and then use the water vapor to drive a generator to produce electricity. The general name of the method. Power plants that use coal, oil, or natural gas as fuel are collectively called thermal power plants.
MaterialReference Baidu Encyclopedia: Electricity Generation