Not every gas in the atmosphere absorbs intensely long-wave radiation from the ground. The greenhouse gases in the earth’s atmosphere are called greenhouse gases, mainly carbon dioxide (CO2), methane, ozone, nitrous oxide, freon and water vapor. They absorb almost all the long-wave radiation emitted from the ground, and only a very narrow region absorbs very little, so they are called “window region”. It is through this window that the earth returns 70% of the heat from the sun to the space in the form of long-wave radiation, thus maintaining the ground temperature unchanged. The greenhouse effect is mainly due to the increase in the number and variety of greenhouse gases by human activities, which makes the 70% value decrease and the remaining heat makes the earth warm.
What is greenhouse gas?
However, although CO2 and other greenhouse gases have a strong ability to absorb long-wave radiation from the ground, their amount in the atmosphere is very small. If the atmospheric state of pressure as a atmospheric pressure and temperature of 0 C is called the standard state, then the whole atmosphere of the earth is compressed to this standard state, its thickness is 8000 meters. At present, the content of CO 2 in the atmosphere is 355 ppm, or 355 parts per million. Converting it to the standard state, it will be 2.8 meters thick. This is 2.8 meters thick in the atmosphere of 8,000 meters thick. Methane content is 1.7 ppm, corresponding to 1.4 cm thick. The ozone concentration is 400 ppb (ppb is one thousandth of ppm), which is only 3 mm thick after conversion. Nitrous oxide is 310 ppb, 2.5 mm thick. There are many kinds of freon, but the most abundant Freon 12 in the atmosphere is only 400 ppt (ppt is one thousandth of ppb), converted to the standard state of only 3 microns. This shows that there are few greenhouse gases in the atmosphere. It is also for this reason that human release without restrictions can easily lead to rapid global warming.
History of development
As early as 1938, British meteorologist Carlinda pointed out that CO2 concentration had risen by 6% since the beginning of the century after analyzing sporadic CO2 observations around the world at the end of the 19th century. He also found that there was a warming tendency in the world from the end of last century to the middle of this century, which caused great repercussions in the world. To this end, Kellin of Scripps Oceanographic Research Institute established an observatory in 1958 at an altitude of 3,400 meters in the Maunaroya Mountains of Hawaii, and began the precise observation of atmospheric CO2 content. Because Hawaii is located in the middle of the North Pacific Ocean. Therefore, it can be considered that it is not affected by terrestrial air pollution and the observation results are reliable.
From April 1958 to June 1991, the atmospheric CO2 concentration in the Maunaroya Mountains was observed. It was found that the atmospheric CO2 content in 1958 was only about 315 ppm, which reached 355 ppm in 1991. The seriousness of the problem also lies in the fact that only about half of the 5.5 billion tons of fossil fuels (about 4 tons of CO2 per ton) that humans burn annually (1996) enter the atmosphere and the rest are mainly absorbed by marine and terrestrial plants. Once the ocean is saturated with CO2, the atmospheric CO2 content will increase exponentially. In addition, they also found seasonal variations in CO2 content, with a difference of 6 ppm between winter and summer. This is mainly due to the winter drought and summer glory of vegetation on the vast continents of the Northern Hemisphere, that is, plants absorb CO2 in summer, which makes the atmospheric CO2 concentration relatively lower.
According to the determination of CO2 concentration in the air of sealed bubbles in the Antarctic and Greenland continental ice sheets, the CO2 content in the atmosphere has been relatively stable for a long time in the past, about 280 ppm. Only from the mid-18th century, before and after the Industrial Revolution began to rise steadily. That is to say, it took 240 years for human beings to increase the atmospheric CO2 concentration from 280 ppm to 355 ppm.
Methane is the second most important greenhouse gas after CO2. Although its concentration in the atmosphere is much lower than CO2, its growth rate is much higher. According to the Second Climate Change Assessment Report issued by the Intergovernmental Panel on Climate Change (IPCC) in 1996, CO2 increased by 30% in 240 years from 1750 to 1990, while methane increased by 145% in the same period. Methane, also known as biogas, is produced when organic matter decays under anoxic conditions. For example, paddy fields, compost and animal manure all produce biogas. Nitrogen monoxide is also known as laughing gas, because inhaling a certain concentration of this gas can cause facial muscle spasm, which looks like laughing. It is mainly produced by burning fossil fuels and organisms using chemical fertilizers. Although the ozone content in the atmosphere decreases in the stratosphere, it increases in the troposphere, which will be discussed later. Freon gases are compounds of chlorine, fluorine and carbon; they do not exist in nature and are entirely human-made. Because of its low melting point and boiling point, non-flammable, non-explosive, odorless, harmless and excellent stability, it is widely used in the manufacture of refrigerants, foaming agents and cleaners. Although the highest concentrations of Freon 12 and 11 in the earth’s atmosphere are very few, their growth rates have been very high in the past, both of which are 5% per year. Because of its severe destruction of the ozone layer in the atmosphere, its concentration in the atmosphere is expected to decrease gradually from the beginning of the 21st century according to the 1987 International Montreal Protocol.
It should be noted that although the atmospheric concentration of greenhouse gases other than CO2 is much lower than that of CO2, some of them are several orders of magnitude smaller, their greenhouse effect is much stronger than that of CO2. Therefore, their contribution to atmospheric greenhouse effect, according to the second IPCC Report, is only one order of magnitude lower than that of CO2. If their total contribution to the greenhouse effect of the Earth’s atmosphere is small compared with CO2 before 1960, it is not negligible that in the near future they will go hand in hand with CO2 and even exceed CO2.
April 2, 2018, DOE Labor
Earthworms, commonly known as earthworms, also known as Eel, are the representative animals of Oligochaeta in annelida. Earthworms are saprophytic living animals. They live in humid environment and feed on corrupt organic matter. They are full of a large number of microorganisms but seldom get sick. This is related to the unique number of antimicrobial immune systems in these earthworms.
In scientific classification, they belong to unidirectional earthworms. The body is cylindrical (distinct from the cylindrical shape of linear animals), symmetrical on both sides and segmented: it consists of more than 100 segments. After the Eleventh segment, there is a dorsal foramen in the middle of the back of each segment; there is no skeleton, it belongs to invertebrates, with bare body surface and no cuticle. Except for the first two segments of the body, all the other segments have bristles. Hermaphroditism, allogeneic fertilization, reproduction by the ring to produce cocoons, reproduction of the next generation. There are more than 2500 known earthworms. Darwin pointed out in 1881 that earthworms are the most important animal group in the world’s evolutionary history.
Body wall and secondary body cavity
The body wall of earthworms consists of cuticle, epithelium, circular muscular layer, longitudinal muscular layer and coelomic epithelium. The outermost layer is a single layer of columnar epithelial cells whose secretions form cuticle. The membrane is very thin, consisting of collagen fibers and non-fibrous layers with small holes. Cylindrical epithelial cells were mixed with fine glands cells, divided into mucous cells and protein cells, can secrete mucus and make the body surface moist. Earthworms encounter intense stimulation. Mucous cells secrete a large amount of mucus to wrap the body into a mucous membrane, which has a protective effect. Epithelial cells have short basal cells at the base, and some people think that they can develop into columnar epithelial cells. Sensory cells aggregate to form sensory organs and disperse between epithelial cells. The nerve fibers of a thin layer of nerve tissue under the epithelium are connected at the base. In addition, there are photoreceptor cells, the base of epithelium, also connected with the nerve fibers below it.
The muscles of earthworms belong to the twill muscles, which generally account for about 40% of the body volume. They are well-developed and flexible. When the longitudinal muscular layer of some segments of the earthworm contracts and the circular muscular layer relaxes, the segment becomes thicker and shorter, and the retracted bristles born on the body wall obliquely extend into the surrounding soil; at this time, the circular muscular layer of the former segment contracts, the longitudinal muscular layer relaxes, the segment becomes thinner and longer, and the bristles retract, thus breaking away from the surrounding soil. The bristle support of the latter segment pushes the body forward. In this way, the contraction wave of muscles gradually passes forward and backward along the longitudinal axis of the body.
The coelomic compartment is separated by the septum according to the body segment, and each compartment is connected with a small hole. Each body chamber is formed by the development of left and right two body sacs. The medial part of the sac formed visceral membranes, while the dorsal and ventral parts formed dorsal and peritoneal mesenteries. In earthworms, the mesentery of the abdomen degenerates, only part between the intestine and the abdominal vessels exists, while the mesentery of the back disappears. The part between the anterior and posterior coelomic sacs is closely together, forming a septum. Some species have no septum in the esophagus.
The digestive tract runs longitudinally in the central part of the body cavity and passes through the septum. The muscular layer of the wall of the digestive tract is well developed, which can improve peristalsis and digestive function. The digestive tract is differentiated into mouth, mouth, throat, esophagus, sand sac, stomach, intestine and anus. The mouth can be turned out from the mouth to ingest food. The pharyngeal muscles are well developed, the muscles contract, and the pharyngeal cavity enlarges to support feeding. There is a single-cell pharyngeal gland outside the pharynx, which secretes mucus and proteinase, moisturizes food and has a preliminary digestive effect. After pharynx, there is a short and thin esophagus with esophageal glands on its wall. It can secrete calcium and neutralize acidic substances. The back of the esophagus is a muscular sand sac (gizzard), lined with a thick cutin membrane, which can grind food. From mouth to sand sac, the ectoderm is formed and belongs to foregut. The digestive tract behind the sand sac is rich in microvessels and glands, which is called stomach. There is a circle of gastric glands in front of the stomach, which functions like pharyngeal glands. The digestive tract enlarges to form the intestine, and its dorsal central fovea enters into a blind canal (typhlosole), which enlarges the area of digestion and absorption. Digestion and absorption are mainly performed in the intestine. The outermost visceral membranes of the intestinal wall specialize into yellow cells. Since the 26th body segment, a pair of conical cecum (caeca) extending forward from both sides of the intestine can secrete a variety of enzymes, which are important digestive glands. The stomach and intestine originate from the endoderm and belong to the midgut. The posterior intestine is relatively short, accounting for about 20 body segments in the posterior end of the digestive tract. It has no blind passage and no digestive function. Open to the body through the anus. The digestive system of earthworms consists of more developed digestive ducts and glands. The digestive ducts are composed of oral cavity, pharynx, esophagus, crop sac, sand sac, stomach, small intestine, cecum, rectum and anus.
Earthworms are very special. Like their body segments without obvious merger, their hearts are also divided into several segments in the front of the body, generally 4-5, which are circular, like enlarged blood vessels, so they are also called circular blood vessels. The dorsal side of the annular heart is connected with the dorsal blood vessel from the back to the front, and the ventral side is connected with the abdominal blood vessel from the front to the back. The abdominal blood vessel and its branches are connected with the inferior nerve blood vessel from the front to the back. The annular heart has thicker muscular walls than blood vessels and pulsates. There are also valves that open unilaterally to ensure blood flow from the dorsal to the abdominal vessels. Generally speaking, the blood flow is powered by the pulsation of these independent annular hearts. The direction of blood flow is from back to front (in the dorsal vessels), from back to abdomen (in the annular heart), and from front to back (abdominal vessels and subnervous vessels).
Respiration and Excretion
The excretory organs of earthworms are posterior renal tubules. In general, each segment has a pair of typical posterior renal tubules.