The earth we live on is surrounded by the atmosphere. The atmosphere, like water, also has pressure. The pressure generated by a 200-kilometer-thick atmosphere near the ground is about 101 kPa, which is equivalent to ten tons of cargo. placed on a square meter of land the pressure generated. Under normal circumstances, the bottle is connected to the outside. The inside and outside of the bottle are affected by pressure. Of course, the bottle will not deflate. When you suck the air or water into the bottle, the pressure inside the bottle. becomes smaller and it is squeezed by external pressure. Deflated.
Water on earth has no shelf life, but water placed in bottles will breed many microorganisms after a while.
The self-cleaning ability of water
The reason water on earth will not expire is because wateron earth has undergone a The water cycle and the water present in water Biological organisms also maintain the cleanliness of water, that is why we say that "water has the ability to clean itself -even ".
We know that there are many organisms in water, which can be roughly divided into three categories based on their types: producers, consumers, and decomposers. Producers are mostly plants that produce energy through photosynthesis. Most consumers are animals that cannot produce energy themselves and need to obtain energy from the outside world. Decomposers, mainly microorganisms, break down organic matter into simple inorganic matter.
Although there are some impurities in this water, organisms in the water can break down these impurities and add them to the biological energy cycle. For example: there may be firesflowers, fallen flowers, etc. in water, but these substances can be eaten by herbivores, or they can be broken down by microorganisms and transformed into simple inorganic substances, which can again be absorbed by plants.
Water cycle
In addition to the self-cleaning ability of water, water also participates in the water cycle.
Water on earth evaporates all the time. After evaporation, water vapor is lighter and rises to high altitudes. When enough water vapor accumulates in the sky, the water vapor condenses with dust, particles, etc. to form small water droplets. Although these small water droplets fall downward, their diameter is small enough, they evaporate again along the way. down. Only small water droplets of larger diameter will drip onto the ground and form rain.
In additionof the atmospheric water cycle, "Nature" magazine also reported that the water cycle also takes place inside the earth. There is a trench near Japan that is currently the deepest known trench in the world: the Great Marigana Trench. The Marigana Trench is located at the subduction boundary, where seawater enters the Earth's interior. According to statistics, hundreds of millions of tons of seawater are swallowed into the Earth's interior every year.
But swallowed seawater will also flow to the surface during the volcanic eruption, completing the water cycle.
Over the 4.6 billion years of Earth's history, the water cycle has unfolded like this. Coupled with the self-cleaning function of aquatic organisms, water impurities were kept at a stable level. level.
However, according to human consumption standards, water from rivers, lakes and seasis considered “stale” water because the number of microorganisms present in the water is very high. Approximately one cup of seawater contains more than a billion microorganisms. Although most microorganisms do not affect humans, this exceeds drinking water standards.
Why does water from the bottle expire?
Actually, drinking water from the bottle also comes from water rivers and lakes, but this water is raw water, it must also go through a series of processes such as precipitation, removal of impurities, disinfection and filtration to clean the impurities from the raw water. It will be injected into the bottle after having been tested to be compliant. standards for human drinking water.
Compared to rivers, lakes and seas, the water in the bottle is a closed system. Only certain microorganisms can survive in this system,which also means they have no natural enemies and can breed in large numbers. .
Although the bottle is sealed and stored, the microorganisms are very small, and many microorganisms reproduce asexually. The reproduction time is relatively short and can multiply from one microorganism to thousands of microorganisms in just 6 hours. . As a result, over time, the number of microorganisms in the bottle will increase significantly and it will no longer be suitable for human consumption. Therefore, mineral water or purified water generally has a shelf life. In other words, it's not that water on earth doesn't have a shelf life, it has a shelf life when it's bottled. But human drinking water has its own set of standards. If it exceeds the standard for drinking water, it is considered “expired”. To a certain extent, river watereras, lakes and seas is also considered obsolete water.
Although expired bottled water cannot be drunk directly, it can be used again as drinking water after boiling in a pot and sterilizing at high temperature.
Summary
Water is called the source of life, but when polluted, it can also be called a “killer” which spreads diseases, such as: The plague epidemic in ancient times was partly caused by drinking contaminated water. Even if there is no plague, excessive levels of microorganisms in water can cause symptoms such as diarrhea and abdominal pain in humans.
For human health and to reduce the risk of spreading infectious diseases, we generally drink treated water, including bottled water. The reason bottled water lasts so longervation is the number of microorganisms during storage. life Will not harm human health.
Although the water of rivers, lakes and seas does not have a shelf life, it has functions of water domestication and biological self-cleaning. Although it contains even more impurities, the total amount of impurities is kept within a relatively stable framework. standard.
But even so, from a human point of view, the water of rivers, lakes and seas is also “outdated water”.