Pros and cons of carbon dioxide
Carbon dioxide helps growth. Increase in CO₂ content fourfold - up to 0.12% of
The results of many years of experiments showed: with an excess of carbon dioxide, the leaves of the trees begin to absorb it more. But at the same time, the trees do not use it for their own development, but simply “drive it through themselves,” again highlighting it through the roots. When the content of CO2 in the soil is more than 1.5%, the roots begin to choke. As it turned out, they are much more important excess oxygen.
Photosynthesisis a process used by plants, algae and some bacteria to take energy from sunlight and convert it into organic substances necessary for their life.
There are two types of photosynthetic processes:oxygenic photosynthesis and anoxygenic photosynthesis. Anoxygenic photosynthesis is a process that occurs in bacteria. It does not produce oxygen. Oxygen photosynthesis is most common and is observed in plants, algae and cyanobacteria. During oxygenic photosynthesis, light energy transfers electrons from water (H₂O) to carbon dioxide (CO₂), resulting in the formation of carbohydrates. During this transfer, CO₂ is “reduced,” or gains electrons, and water is “oxidized,” or loses electrons. Photosynthesis produces sugars and oxygen.
Photosynthesis proceeds in two phases. The first is called the light, the second - dark. The light phase of photosynthesis allows you to directly convert light energy into chemical energy due to sunlight. About 15 seconds after the plant absorbs carbon dioxide, a dark synthesis reaction occurs and the first products of photosynthesis appear - sugar: trios, pentoses, hexoses and heptoses. Of certain hexoses, sucrose and starch are formed. In addition to carbohydrates, lipids and proteins can also be developed by binding to the nitrogen molecule.
The light phase occurs on the membranes of the thylakoids of the chloroplast, and the dark phase occurs in the stroma of the chloroplast.
But the irreversible processes that causeincreased levels of carbon dioxide in the air have already begun. A study published in the journal Nature in 2014 shows that rice grown in high carbon dioxide environments contains lower amounts of important nutrients. The potential health implications are significant, given that billions of people around the world already do not get enough protein, vitamins and other nutrients from their daily diets.
Dr. Zisk, plant physiologist at the MinistryUSDA, and his colleagues created experimental rice fields in China and Japan with elevated concentrations of carbon dioxide, which scientists expect in 100 years. The researchers focused on rice because it is the primary source of food for 2 billion people worldwide. The 18 varieties of rice that were grown and harvested, with few exceptions, contained significantly less protein, iron and zinc than rice grown today. All varieties had a sharp decrease in the levels of vitamins B1, B2, B5 and B9, but they contained more vitamin E.
The process of photosynthesis in plants includesa series of stages and reactions that depend on solar energy, water, and carbon dioxide. CO₂ serves as a source of carbon, it enters into the process of photosynthesis in a series of reactions called carbon fixation steps (also known as dark phase reactions). These reactions follow the stages of energy conversion (or light reactions), which convert solar energy into chemical energy in the form of ATP and NADP molecules, providing energy for starting carbon fixation stages.
Carbon dioxide gets into most plants.through the pores (stomata) on the surface of leaves or stems. In photosynthesizing algae and cyanobacteria, CO₂ is absorbed from the surrounding water. Once in the photosynthetic cell, CO₂ is “fixed” with the organic molecule using an enzyme. In many plant species, this initial reaction is catalyzed by the enzyme Rubisco, the most abundant enzyme in the world.
In a series of reactions called the Calvin cycle,The carbon-containing molecule resulting from this first fixation reaction is converted to various compounds using energy from ATP and NADP. Products of the Calvin cycle include simple sugar, which is subsequently converted into carbohydrates - this is glucose, sucrose and starch. They serve as important sources of energy for the plant. The cycle also regenerates the molecules of the source reagent, with which more carbon dioxide will be associated in the next stage of the cycle.
Pipes were installed on the experimental field.which emitted carbon dioxide into small open-air areas (rather than simply testing crops in closed greenhouses) to simulate future real-world conditions. In plants that are subject to the so-called Calvin cycle, including rice and wheat, increasing the concentration of carbon dioxide can stimulate the production of more carbohydrates that affect the nutrient content. But scientists are still trying to understand why some compounds, such as vitamin B, are dependent on changes in atmospheric air, while others do not, or why some rice varieties have a more dramatic decrease in vitamin B levels than others.
Sidebar
After a series of studies in this area, scientistswill be engaged in the creation of genetically modified crop varieties that will retain most of their nutritional value in the face of increasing concentrations of carbon dioxide. But it can be incredibly difficult, considering that all the rice varieties tested showed a significant decrease in vitamin B levels, Dr. Zisk notes.
Another possible solution is to reduce anthropogenic pollutionvolumes of carbon dioxide emissions. Currently, atmospheric CO₂ levels average around 410 ppm (approximately 0.04%), up from 350 ppm in the 1980s. This pattern is mainly due to the burning of fossil fuels.
The average decrease in grain protein with increasedcompared to the surrounding CO₂ for 18 cultivated paddy lines of contrasting genetic background grown in China and Japan using FACE technology.
The average decrease in the concentration of trace elements ingrain, iron (Fe) and zinc (Zn) with increased CO₂ for 18 cultivated rice lines of contrasting genetic origin, grown in China and Japan using FACE technology.
Useless vegetables
Fruits and vegetables grown decades ago, byScientists' assurances were richer in vitamins and minerals than the varieties we currently eat. The main cause of this alarming trend in our diet was soil depletion: modern aggressive methods of achieving maximum benefits in agriculture have led to a catastrophic decrease in the amount of nutrients in the soil. Unfortunately, each subsequent generation of fast-growing, beautiful, pest-resistant carrots becomes even less useful than the previous one.
Donald Davis and his team from TexasUniversity examined USDA nutrition data for 1950 and 1999 for 43 different vegetables and fruits and found “real declines” in protein, calcium, phosphorus, iron, riboflavin (vitamin B2) and vitamin C over the past half century. Davis attributes this reduction in nutrient content to the fact that modern agriculture is aimed at improving the quality traits (size, growth rate, pest resistance) of the resulting crop.
Organic Consumers Associationcompared several studies with similar results: an analysis of nutrient data by the Kushi Institute from 1975 to 1997 found that the average calcium level in 12 fresh vegetables decreased by 27%, iron levels by 37%, and vitamin A levels by 21 %, and the level of vitamin C by 30%. And nutrient data from 1930 to 1980, published in the British Food Journal, showed that the average calcium content of 20 vegetables fell by 19%, iron by 22% and potassium by 14% during that time. It turns out that modern people need to eat eight oranges a day to get the same amount of vitamins A and C that our grandparents would have gotten from just one fruit.
Endangered bees
Scientists are also alarmed by the decline inpollinators. About 74% of all globally produced fats are present in oils from plants dependent on insect pollination. These plants also serve as major sources of fat-soluble vitamins. Of the water-soluble vitamins, 98% of vitamin C comes from pollinated plants, citrus fruits and other fruits and vegetables. Although scurvy due to C deficiency is now rare, its important role, along with E and beta-carotene, is not diminished in any way in modern realities. Water-soluble B vitamins are rich in starchy grains that thrive regardless of pollinator deficiency. However, most of these nutrients are lost when whole grains are processed into white rice or white flour, for example. While the US has corrected this deficiency by introducing whole grain flour, brown rice and other unrefined foods, 2/3 of the world's population does not have access to fortified grains.
Since the early 2000s, beekeepers have reported massivedeath of honey bees. Adult bees, as a rule, disappeared without a trace, not returning to the hives. These cases attracted public attention, and rumors of various causes of the phenomenon ranged from climate change to radioactive signals from mobile phones and genetically modified crops.
A large research team found out: although an Israeli paralytic bee virus was detected in the bees, it could not cause such a catastrophic extinction. The number of bees is rapidly declining in recent years. Some of them were added to the endangered list in 2017 (seven species of Hawaiian bees) and in 2018 (the Bumblebee Bombus affinis).
Each year, the number of pollinating bees decreases, and some species are on the verge of extinction.
Intensive use of pesticides knownas neonicotinoids (a relatively new class of insecticides that affect the central nervous system of insects, leading to paralysis and death), played an important role in reducing the population of bees. When bees are exposed to neonicotinoids, they have a strong effect on the nervous system (something like the Alzheimer's version for insects) and suffer from severe disorientation.
Along with pesticides, parasites known asVarrao mites are also responsible for the mass death of bees. Varrao can breed only in the bee colony. These blood-sucking parasites equally affect both adults and young bees. The disease caused by these mites can cause the bees to lose legs or wings, slowly and painfully dying.
Whole grain cereals are an important naturalsource of B vitamins, especially folic acid. The need for folic acid increases during pregnancy to prevent fetal neural tube defects. More than 70% of vitamin A and 98% of each of the carotenoids, cryptoxanthin (provitamin A) and lycopene are found in crops that are pollinated by insects. It is unknown to what extent these plants, including red, orange and yellow vegetables and fruits, can reproduce without pollination, but experiments have shown a direct 43% increase in yield due to natural pollination. Vitamin A is one of the most essential elements for the body, and its deficiency causes up to 500 thousand cases of irreversible blindness in children around the world every year. Diets high in carotenoids are beneficial for people prone to cancer; In laboratory tests, lycopene has shown its ability to slow tumor growth. Most vitamin E is also found in plants that require pollination.
Soil depletion, air pollution andthe extinction of bees is only the consequences of the illiterate attitude of humanity to a large, but so fragile and vulnerable planet. People, plants, animals, land and air are inextricably linked, and every irresponsible step of a person can turn into a real tragedy for the whole world. Scientists will probably be able to restore the nutritional value of fruits, vegetables and cereals, but this is not the only direction of development of our planet. It is necessary to reduce carbon dioxide emissions, relieve the load on the soil and take care of the animal world, preventing the extinction of whole species.