This environmental process is affected by air pollution; it is the movement of hydrogen around the EarthThis chemical element is the most abundant in the universe and on Earth, comprising 84% of it, and is an essential part of the composition of water, biomolecules and atmosphere.
On our planet, we can find it in the water and air we breathe, but also in the living things, soils, rocks and fuelsIn light of this fact, we must emphasize the preservation of the natural components that modify it and maintain its balance. Research on the hydrogen cycle It can be of great help in starting to raise awareness in global society about the importance of this element and its relationship with other biogeochemical cycles.
What is the hydrogen cycle?
El hydrogen cycle It is a biogeochemical cycle through which hydrogen moves and transforms through the planet's main reservoirs: hydrosphere, atmosphere, biosphere and geosphereThis displacement occurs primarily through water, although it also plays a role in processes such as... Photosynthesis, respiration, and the decomposition of organic matter and chemical reactions in soils and oceans.
The hydrosphere obtains hydrogen primarily from water (H2O), a compound formed by the combination of oxygen and hydrogen. During processes such as photosynthesis, the dissociation of water occurs and some of that hydrogen ends up forming glucose and other carbohydrates when it combines with carbon dioxide (CO2). Thus, hydrogen passes from water to plants and from them to animals and humans through the food chain.
Plants provide food for herbivores, and these animals obtain glucose, proteins and other nutrients of plants. Hydrogen is an essential part of the carbohydratesHydrogen, which is an important source of energy for living beings, reaches our bodies through food. When living beings breathe, grow, reproduce, or die, hydrogen is involved in all these transformations.
There are countless types of living things on Earth. They are all basically composed of carbon, nitrogen, oxygen and hydrogenAnimals obtain these elements from nature, and the processes of formation, growth, and decomposition occur continuously, releasing and reincorporating hydrogen into the planet's various reservoirs.
Several cycles occur as a result of each of these processes (carbon cycle, nitrogen cycle, sulfur cycle, water cycle, among others), and because of them, everyone is linked together, establishing a dynamic equilibriumHydrogen is a key component of many of these cycles, so altering its availability or distribution can have large-scale effects on climate, soil fertility, and the life of entire ecosystems.
Phases of the hydrogen cycle
Hydrogen atoms can be represented as liquids or gasNature stores hydrogen in liquid form when it is part of water or other compounds, since in its gaseous state it occupies much more space. At a physicochemical level, hydrogen can also be stored as... high-pressure gas or liquid hydrogen for industrial and energy purposes, since it occupies less volume than in its normal gas form.
When a hydrogen atom bonds to a strongly electronegative atom (such as oxygen, nitrogen, or fluorine) that is close to another electronegative atom with a lone pair of electrons, a hydrogen atom is formed. hydrogen bondThese bonds are responsible for many properties of water and its structure. proteins, DNA and other biomoleculesIn addition, two hydrogen atoms can form a molecule of hydrogen gas (H2), which is widely used at the industrial and energy levels.
El The water cycle and the hydrogen cycle go hand in hand for the flowering and nourishment of plants through the photosynthesisHydrogen is part of the water molecule, so every time water changes state or moves in nature, a redistribution of hydrogen also occurs. Therefore, hydrogen is fundamental in processes such as... the hydrological cycle, the carbon cycle, the nitrogen cycle, and the sulfur cycle.
Moreover, the organic decomposition The water produced in soils contains high levels of hydrogen. As plants and animals die, their remains are incorporated into the soil as organic matter; during decomposition, various chemical reactions release hydrogen-containing molecules back into the atmosphere, soils, or groundwater through processes of oxidation and mineralization.
The hydrosphere includes the atmosphere, the Earth's surface, surface water, and groundwaterAs water moves through the cycle, it changes state between liquid, solid, and gaseous phases, carrying with it the hydrogen it contains. This movement occurs between different reservoirs, including oceans, rivers, lakes, glaciers, aquifers, clouds and soilsthrough physical processes such as evaporation, transpiration, sublimation, precipitation, infiltration, runoff, and groundwater flow.
Evaporation
El hydrological cycle and hydrogen cycle They are deeply related, since the hydrological cycle is the setting where hydrogen fulfills a large part of its ecological functions. evaporation from the water surface Oceans, rivers, lakes, reservoirs, and wet soils are the beginning of it all. When water evaporates due to solar energy, it changes from a liquid to a gaseous state (water vapor) and rises into the atmosphere, carrying hydrogen atoms within its molecules.
At this stage, it is also important to evapotranspirationThis process combines direct evaporation from the soil with transpiration from plants. A significant portion of the water that enters the atmosphere originates from terrestrial ecosystems, making forests and areas with abundant vegetation key players in the hydrogen cycle.
Condensation
The atmosphere condenses the water that evaporates through the hydrological cycle, changing it from a gaseous to a liquid state. As it rises, the water vapor cools and transforms into... small liquid droplets or ice crystalsforming clouds and fog. During this process, the hydrogen atoms present in the water molecules group together into new structures and become available again to fall onto the surface.
The ocean, glaciers, groundwater, precipitation, sublimation, seepage, and surface runoff all participate in phases before and after condensation, carrying water that will again be condensed by the atmosphereThus, condensation is the step that prepares water to return to Earth in the form of rain, snow, or hail, allowing the redistribution of hydrogen among different ecosystems.
Perspiration
A clear example of this process occurs when the plants absorb water through their roots, plants pump water to the rest of their bodies, supplying the necessary nutrients and hydrogen. Afterward, the water is released from the plants through their pores (stomata) as vapor, which passes into the atmosphere. In this way, the hydrogen contained in the water circulates from the soil to the air, passing through the plant tissues.
Perspiration represents approximately 10% of the water that evaporates in the worldIt is the release of water vapor from plant leaves into the atmosphere, a process invisible to the naked eye, even though the amounts of moisture involved are very significant. For example, it is estimated that a single large oak tree can transpire more than hundreds of thousands of liters of water per yearthus contributing significantly to the local water and hydrogen cycle.
The amount of water transpired through this process depends on factors such as plant species, soil moisture, ambient temperature, and wind around the vegetation. Areas with high vegetation cover have higher relative humidity for this reason, which influences the regional climate and the balance of available hydrogen.
Precipitation
La precipitation It occurs due to the cooling of water droplets in the atmosphere, which then precipitate due to their weight and size. It can manifest as rain, snow, hail, or drizzle, returning water to the Earth's surface and with it... hydrogen atomsOnce the water reaches the ground, it gives way to infiltration and runoff, processes by which water is incorporated into the subsoil or flows across the surface into rivers and seas.
This process is repeated continuously as part of the Earth's cycles that maintain the renewable freshwater resourceslife depends on. Each precipitation event redistributes hydrogen in the environment, replenishing aquifers, feeding surface water bodies, and providing essential liquid for plant growth and human consumption.
Solidification
Solidification occurs when water evaporates or water droplets contained within the atmosphere solidify due to a change in temperature and produce hail or snowIn this phase, water changes from a liquid to a solid state, but it still contains the same proportion of hydrogen atoms. Later, the following occurs: fusionwhich is when the ice and snow melt and return to a liquid state, allowing the water to resume its journey to rivers, lakes and oceans.
In cold or high mountain regions, a large amount of hydrogen remains stored for years or centuries in the form of ice in glaciers and polar ice capsThese large reservoirs act as stores of fresh water and hydrogen, gradually releasing it through seasonal melting and thus contributing to the balance of the global cycle.
Infiltration
La infiltration This is when water returns to the soil and seeps into it to become available again to plants and their roots. As the water filters down, it nourishes deeper soil horizons and can reach aquifers and underground reservesIn these underground water bodies, hydrogen remains integrated into the water molecule, available for extraction through wells or to be used by vegetation through deep roots.
This process is also key to the natural water purificationBecause, as water passes through the different layers of soil, many impurities are retained. In this way, the hydrogen-containing water reaches the aquifers cleaner, where it becomes a vital reserve for human, agricultural, and industrial use.
Runoff
La runoff It is the term used to refer to the act of water spreading across the soil. It is the flow of water that circulates over the Earth's surface when the soil is saturated or rainfall is very heavy. This movement carries sediments, nutrients, and, of course, water molecules containing hydrogen, transporting them towards rivers, lakes, wetlands and, finally, oceans.
Runoff helps connect inland waters with the seas and is part of the circuit through which hydrogen returns to large aquatic reservoirs. Furthermore, it influences the erosion of the landscape, the fertility of the floodplains and the dynamics of nutrients in aquatic and terrestrial ecosystems.
Underground circulation
La underground circulation This occurs when water has penetrated the soil and reaches rivers, lakes, and seas again. The infiltrated water can move slowly through the subsoil and resurface in springs, natural sources or resurgences in the riverbedThis entire process keeps hydrogen in motion, which is exchanged between deep layers, soils, vegetation, and surface water bodies.
This underground process is less visible than surface runoff, but it is fundamental to the long-term water regulationThanks to underground circulation, a more stable water supply to ecosystems is guaranteed even in dry periods, meaning that hydrogen remains available to sustain life and human activities.
Importance of hydrogen on Earth
Hydrogen is vital for the survival of humankind and the rest of living beings due to various factors. For example, plants provide other living beings with all the nutrients necessary for their development. The herbivorous animal receives hydrogen from the plant in the form of carbohydrateswhich in turn become the organism's primary energy source. Later, when a carnivore feeds on a herbivore, that hydrogen continues to be passed through the food chain.
Also the life processes In general, they are related to hydrogen, since most living beings are composed of atoms of nitrogen, hydrogen, and oxygenIn addition to carbon, hydrogen is part of molecules as important as... water, nucleic acids, proteins, lipids, and sugarsTherefore, it participates in the structure and function of all cells.
At a physical and technological level, hydrogen has a wide variety of practical usesBeing the lightest element, it can serve as lifting agent for balloons and airshipsHowever, its high flammability requires extreme caution. This same property, combined with its ability to release a large amount of energy when reacting with oxygen, makes it a very interesting fuel for different applications.
Hydrogen is primarily used for create water when combined with oxygen, and hydrogen gas can be used in the reduction of metallic minerals in industrial processes. The chemical industries also use it for the hydrochloric acid production and for the synthesis of numerous compounds, including the ammonia (NH3), the basis of many fertilizers and household cleaning products.
Furthermore, hydrogen is necessary for the atomic hydrogen welding (AHW) and is used as rocket fuelwhere it is usually combined in the form of liquid hydrogen with liquid oxygen to form a highly energetic mixture. It is considered one of the cleaner fuelsbecause, when burned, the main product is water, without generating carbon dioxide or other greenhouse gases at the point of use.
Electric generators use hydrogen gas as refrigerantwhich has led many plants to use it as an agent for the leak checkIt also has applications in the food processingFor example, in the hydrogenation of fats, where hydrogen atoms are added to modify unsaturated oils and transform them into fats with other physical properties.
Renewable hydrogen and its production stages
In recent years, great emphasis has been placed on the development of renewable hydrogen or green hydrogen, a type of hydrogen produced without direct carbon dioxide (CO2) emissions. Instead of using fossil fuels, this hydrogen is generated from renewable energy such as wind, solar or hydroelectric power, which makes it a key tool for the decarbonization of the economy.
Renewable hydrogen production units operate in several fundamental stages which allow obtaining a high purity gas suitable for storage, transport and use in different industrial and transport sectors.
- electrolysis of waterHydrogen is produced from water from rivers, oceans, rain or even leachateOnce treated and conditioned, electrolysis is a process that breaks the chemical bonds of water molecules (H2O) by means of an electric current applied between two electrodes. To make the process renewable, it uses electrical energy from renewable sourcesDuring electrolysis, the following is released: oxygen (O2) to the air as a byproduct, and there is no CO2 emission associated with the water molecule separation process itself.
- Compression of hydrogen (H2)Once produced, hydrogen is normally found at low pressure. To facilitate its storage and transportationIt undergoes a compression process that reduces the gas volume and increases its pressure. This allows for a greater quantity of hydrogen to be loaded into the tank. cylinders, tanks or containers intended for industrial use or as fuel.
- Hydrogen purification: in this stage the traces of oxygen, water vapor, or other impurities that might have remained after electrolysis and compression. The result is high-purity hydrogen, necessary for sensitive applications such as fuel cells, fine chemical processes, or certain industrial uses where the presence of contaminants could cause corrosion, decrease performance, or generate unwanted reactions.
Transport and uses of renewable hydrogen
Once produced, renewable hydrogen must be transported and stored safely so that it can be used at different points of consumption. There are several ways to do this, depending on the quantity required, distance and type of application.
When it is needed for a factory or industrial plant In large quantities and continuously, hydrogen can be transported directly through a pipeline networkThis pipeline connection allows the factory to be supplied for uses such as the production of glass, steel, plastics, food, chemicals and other industrial sectors that demand large volumes of this gas.
Hydrogen can also to be stored in pressurized containers outside the production plant and then transported by truck, ship or trainDepending on the available infrastructure. This method is mainly used for medium or short distances and to supply hydrogen refueling stations, small industries, or vehicle fleets.
Among the most prominent uses of renewable hydrogen are:
- TransportHydrogen can power fuel cell vehicles (cars, buses, trucks, trains, or even ships). These vehicles generate electricity on board from hydrogen and oxygen, and only emit steam When driving, it emits zero CO2. It is a very interesting alternative for heavy or long-distance transport.
- IndustryRenewable hydrogen can be used as clean raw material or fuel for different factories, either in large quantities via pipelines or in smaller volumes via containers. Its use allows reduce carbon footprint of processes that traditionally used natural gas or coal to obtain heat or fossil-based hydrogen.
Hydrogen production using renewable energy results in a fuel clean from its origin to its final useIn this way, it becomes a very effective tool for decarbonize companies, cities and transport systemsprovided it is accompanied by good energy planning and adequate infrastructure.
How does hydrogen get to our body?
Hydrogen is present in most of the foods and beverages we consume daily. The human body is composed of approximately one 70% waterand each water molecule contains two hydrogen atoms. Furthermore, the proteins, fats and carbohydrates Our diet also contains hydrogen in its chemical structure.
Adequate consumption of water and foods rich in organic compounds allows hydrogen to participate in the regulation of the body's pHin metabolic reactions that produce energy (such as cellular respiration) and in the synthesis of new molecules essential for life. Without this continuous supply of hydrogen, our metabolism could not function properly.
To maintain a hydrogen-rich diet, in the sense of favoring the consumption of foods with high water content and healthy compounds, it is recommended to consume fresh fruits and vegetablesas well as a sufficient amount of pure water. Among the especially hydrating foods are... Citrus such as tangerines, oranges, and lemons, as well as strawberries, melon, watermelon, and other fruits. Of course, the water we drink daily It is the main direct source of hydrogen for our body.
What are the dangers and precautions associated with hydrogen?
Despite being fundamental to human existence, the hydrogen gas It is highly flammable and can be dangerous under certain conditions. low molecular weight It causes it to rise rapidly in the atmosphere, but if it becomes confined in enclosed spaces and mixes with oxygen in certain proportions, it can lead to explosions and flames difficult to see, which increases the risk.
For a person suffering from any respiratory insufficiency or severe lung problems, inhaling large amounts of hydrogen in a poorly ventilated place can be harmful, as this gas displaces the oxygen from the air and reduces the amount available for breathing. This triggers a state of hypoxia or poisoning throughout the body. It is not hydrogen itself that is toxic, but the lack of oxygen that it causes when it displaces it.
Therefore, in industrial environments it is advisable to have a accurate measurement of hydrogen concentrations in the environment To avoid these risks, proper ventilation and the use of leak sensors are essential. It is also crucial to have security systems that cut off the supply if explosive mixtures or significant leaks are detected.
On the other hand, it is necessary to stay away from the industrial zones that implement large quantities of hydrogen in the manufacture of certain products when there is no adequate training or protective equipment, as it can cause explosions or fires If all required safety measures are not applied. Like other flammable gases, it must be handled responsibly and following strict protocols.
Although hydrogen is one of the cleaner fuels availableIts widespread use requires investment in secure infrastructure, reliable storage systems, and appropriate safety standards. This minimizes risks and maximizes its environmental advantages over traditional fossil fuels.
Environmental education and preservation of natural cycles
To ensure environmental protection, it is necessary to intervene in the Spanish education system in countries with the lowest development index and also strengthen environmental education at all levels. Implementing strategies for individuals to coexist with natural processes will make them much more aware of its surroundings and the importance of preserving it.
Thus, humans can be capable of maintaining the environment in good condition in which they live. future generations will grow. Understanding how the hydrogen cycle works and its relationship to other biogeochemical cycles helps us understand why phenomena like the pollution, deforestation, or climate change They can seriously disrupt the balance of nature.
But what should I do so that the natural cycles such as hydrogen Are they fulfilled perfectly? You can start by investigating in depth what they are. sustainable habits that you should implement in your daily life (saving water, reducing waste, using energy responsibly, conscious consumption) and what are the Communication strategies that are better suited to your abilities so that you can carry the message of awareness to others.
If you are a parent, you can start by giving your children a Parenting with positive values that are in harmony with natural processes and cycles. Talking about the importance of conserving water, respecting plants and animals, and understanding how everything on the planet is connected fosters the development of people who are more environmentally responsible.
Making informed decisions, supporting clean technologies such as renewable hydrogen And demanding public policies that protect ecosystems are steps that, added together, strengthen the preservation of the hydrogen cycle and all the processes that sustain life on Earth.
Understanding the role of hydrogen as an abundant element, its constant passage between water, air, soil, and living organisms, and its potential as a clean energy source allows us to much better appreciate the need for take care of natural cycles and to move towards development models that respect the planet's limits.