The mud has already "written" the "diary" down the rivers and lakes, and the scholars use diatoms to reveal the change of Wuhan Lake

The unsightly diatoms of the naked eye have become an important clue to explore the history of the evolution of lakes. On September 18th, the third season of the third season of Natural General Course planned by Academician Gui Jianfang's Natural Science Popularization Studio invited the Department of Geography Science, Biology and Environmental Geology, the School of Geography and Information Engineering, China University of Geosciences (Wuhan). The key laboratory Mr. Chen Xu said, sharing how the diatoms sleeping in the bottom mud record the changes in the environment of Wuhan Lake.

The diatom is "file" for the lake environment change

Professor Chen Xu shared the changes in the environment of Wuhan Lake.

Before the formal lecture, Chen Xu took the children who participated in the wetland research activities to the lake of the Jiefang Park, collected diatom samples in the aquatic grass, and brushed the diatom into the test tube with a toothbrush.

"There is only a drop of water in my test tube. Is there really diatoms in it?" Facing the doubts of teenagers, Chen Xu explained that the length of the diatom individual ranges from 2.5-2000 microns, and the naked eye could not be observed. As a single -cell creature, the diatoms are composed of two silicon shell petals: one large and small, and the two can be deducted. , Columnar, discs, and bridge curved diatoms. At present, more than 20,000 diatoms have been identified worldwide, and there are more than 100 species in the lakes of Wuhan. "

How is small diatoms in the scientific community? Chen Xu said that diatoms not only survived lakes, oceans, and streams, but also can breed offspring on soil, peat wetland and humid bark. The diatoms are sensitive to the environmental changes. When the water environment changes, the advantages are replaced. After the diatom dies, the silicon shell will be saved into the bottom of the lake, so the diatom in the mud in the cumulative lake naturally becomes a loyal recorder of the environmental change. "Scientists are the diatoms that sleep in the bottom mud, and the history of the lake evolution is unveiled."

Chen Xu made an analogy. The accumulation of mud of the lake bottom is similar to the growth process of the tree annual wheel. In winter, the precipitation becomes less, and the runoff will decrease, and the dark granules are piled up with fine particles. Scientists collect these bottom mud samples and analyze the bottom mud at the same distance. " After introducing the principle, Chen Xu instructed the teenager to carry out microscope observation: Take out the diatom sample in the test tube with a straw to drip on the glass slice and make a simple glass piece, and observe it through the microscope.

Under a microscope, some diatom gods are like bamboo, which belongs to the genus of straight chain algae; some are thin and middle -like in the middle, which are crispy algae, which are attached to the aquatic plant and the bottom mud to grow. Water body environment. And if a large number of algae in the shape of tires appear, it means that the water quality of the lake is deteriorated. "By analyzing the diatom combination of different levels of mud, you can roughly infer the environment of the lake in the past." Chen Xu added that combined with the lake pattern layer and radioactive environmental nuclein 铯 137 and other annual methods, it can accurately infer the age of lake bottom mud. The combination of the two can read the "diary" that the lake itself has recorded.

Potential ecological environmental risks of "micro -plastic"

Professor Chen Xu brought the diatoms in the aquatic grass with youth.

In the lecture, Chen Xu mentioned that the deterioration of the lake environment has a lot to do with human behavior. "For example: put plastic into the lake, or leave heavy metal substances, it will affect the water quality of the lake." Since the 1990s, population growth has brought about economic development, and the followers of lakes and housing buildings have led to a decrease in the area of ​​lakes. This is also an important factor in the worsening environment of the lake.

Chen Xu compared the two states of the lake environment: in the state of healthy water, a large amount of aquatic plants grow; non -healthy turbid water state, a large amount of algae grows, "Lake water quality is resistant to polluting small rings and algae. In addition, in addition, in addition In recent decades, the average annual wind speed of the world has declined, the water bodies of lakes have weakened, and small rings that are prone to floating are more advantageous in the water body. "

Lakes are responsible for everyone. Chen Xu takes "micro -plastic" as an example to emphasize the importance of public participation in environmental protection. Plastic bottles and plastic bags in daily life will become "micro -plastic" after the decomposition, and it is easy to enter the organism. When we drink plastic bottled water, we also consume "micro -plastic". Although the current impact of "micro -plastic" on human health is not clear, due to the large surface area of ​​these tiny particles, it is easy to absorb toxic substances such as heavy metals, and its potential environmental risk cannot be ignored. Therefore, in daily life, the public should eliminate the abandonment of plastic garbage in lakes and wetlands to prevent ecological environment risks caused by "micro -plastic".

Wuhan continues to exert its wetland protection

Young people observe diatoms through optical microscope.

"Thousands of Lakes" and "Hundred Lakes City", Wuhan has always had the reputation of wetland capital. Chen Xu showed a map of the nationwide lakes. There were about 2,600 lakes in more than 1 square kilometer nationwide, of which 598 were sitting in the middle and lower reaches of the Yangtze River, of which the lake distribution in Wuhan was particularly dense. Not only is there a large number, Wuhan also has one internationally important wetland, one important wetland of the country, 5 national wetlands parks, and a national urban wetland park. These wetlands are of great significance to the protection of global biodiversity.

"With the sedimentation diatoms of lakes, we can gradually establish a key lake environmental change file in Wuhan in the future." Chen Xu told everyone that by using the "archive records of mud" in the bottom of the lake, the lake and water environment in the historical period can be restored to the lake environmental protection. Provide the benchmark information, predict the future evolution of lakes, and help the ecological environmental protection of the lake in Wuhan. In November of this year, Wuhan will organize the 14th Conference of the Convention on the Wetland Convention on behalf of China for the first time. With the theme of "cherishing wetland, harmonious coexistence of human and nature", the development of strategic development of the Convention on the Convention, and released the "Wuhan Declaration" for the "Wuhan Declaration", as for the "Wuhan Declaration". Realize a new contribution of a better future of human and nature. In Chen Xu's view, lake environmental protection is not only the government's responsibility, but also the participation of all citizens. Protecting the wetland is a home that protects us and descendants.

Yangtze Review ｜ Science popularization of the whole people requires more "masters"

(Changjiang Daily reporter Guo Kezhen Cai Yanqiu Correspondent Zhao Huijuan)

【Edit: Zhang Jing】

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