How does wetland store flood, prevent drought and regulate climate?

Wetlands have many functions. They can be used as direct water source or supplementary groundwater, effectively control floods and prevent soil desertification, and can also retain sediments, toxic substances and nutrients, thus improving environmental pollution. It can store carbon in the form of organic matter, reduce the greenhouse effect, protect the coast from wind and waves, and provide clean and convenient transportation ... It is called "kidney of the earth" because of its rich and beneficial functions. Wetland is also a paradise for many plants, animals, especially waterfowl. At the same time, providing food (aquatic products, livestock products, grains), energy (hydropower, peat, firewood), raw materials (reeds, wood, medicinal plants) and tourist sites for human beings is an important foundation for human survival and sustainable development.

Regulating function of atmospheric composition

The rich plant communities in wetlands can absorb a lot of carbon dioxide gas and release oxygen. Some plants in wetlands also have the function of absorbing harmful gases in the air, which can effectively regulate the atmospheric composition. But at the same time, it must be noted that wetland habitats will also emit greenhouse gases such as methane and ammonia. Marsh has great biological production efficiency. In the process of organic matter formation, plants constantly absorb CO2 and other gases, especially some harmful gases. Oxygen in the swamp is rarely consumed in the decomposition of dead plant residues. Swamp can also absorb dust and various bacteria in the air, thus purifying the air. In addition, swamp sediments have great adsorption capacity, and sewage or industrial wastewater containing heavy metals can adsorb metal ions and harmful components through swamps.

Water regulation function

Wetlands play an important role in storing water, regulating river runoff, replenishing groundwater and maintaining regional water balance. It is a natural "sponge" for water storage and flood control, which can distribute uneven precipitation in time and space, and avoid floods and droughts through the adjustment of wetland throughput. Qilihai Wetland is an important flood storage and detention area in Tianjin coastal plain, with a safe flood storage depth of 3.5-4m.

Marsh wetland has the function of moistening climate and purifying environment, and is an important part of ecosystem. Most of them are developed in negative landform types, with long-term water accumulation, dense plant growth, intertwined roots and accumulation of residues. Submerged swamps generally have tens of centimeters of grass roots. The grass-root layer is porous and has strong water-holding capacity, which can keep 3 ~ 15 times of its absolute dry weight. It can not only store a large amount of water, but also continuously send water back to the atmosphere through plant transpiration and water evaporation, thus increasing air humidity, regulating precipitation and playing a good role in the natural circulation of water. According to experimental research, one hectare of swamp can evaporate 74 15 tons of water in the growing season, which shows its great role in regulating climate.

Purification function

Swamp wetland is like a natural filter, which helps to slow down the flow of water. When running water containing poisons and impurities (pesticides, domestic sewage and industrial discharge) passes through the wetland, the slow speed is beneficial to the precipitation and removal of poisons and impurities. Some wetland plants can effectively absorb toxic substances in water and purify water quality.

Swamp wetland can decompose and purify environmental objects and play the functions of "detoxification" and "detoxification", so it is called "kidney of the earth". If there is no wetland, it is like a person's kidney being cut off.

Organic substances such as nitrogen, phosphorus and potassium are stored biologically through complex physical and chemical changes, or they are permanently separated from wetlands and participate in a wider cycle through biological transfer (such as harvesting plants and fishing).

There are a considerable number of aquatic plants in swamp wetlands, including floating, buoyant and submerged plants, which have strong detoxification ability and are the bane of poisons. According to the determination, the concentration of heavy metals in wetland plant tissues is 6.5438+10,000 times higher than that in the surrounding water. Because of this, people often use this ecological function of wetland plants to purify viruses in pollutants and effectively remove "toxins" in sewage to achieve the purpose of purifying water quality.

Such as water hyacinth, cattail, reed, etc., are widely used to treat sewage and adsorb high concentrations of heavy metals such as cadmium, copper and zinc in sewage. In Florida, USA, someone did the following experiment. Let the wastewater flow through a cypress swamp (a kind of wetland) before it is discharged into the river. After determination, it is found that about 98% of nitrogen and 97% of phosphorus have been purified and eliminated, which shows the amazing removal ability of wetlands to pollutants. In Karkuta, India, there is a sewage treatment plant in the city. All domestic sewage is discharged into the constructed wetland in the eastern suburbs, and its sewage treatment cost is quite low, which has become a world model.

Regulate local microclimate

The moisture in the wetland becomes steam through evaporation, and then falls to the surrounding areas in the form of precipitation, thus maintaining the local humidity and rainfall, making Ninghe County one of the wetter areas in Tianjin.