A rock goby swims calmly, stuck to the bottom of the pond. Try putting some shellfish in your mouth. He ignores, like the rest of the living things, what is going on inside the cellular machinery. There, on the smallest scale, it all comes down to the chemistry of the elements. Nitrogen, for example, is a key component of the nucleic acids that make up your DNA. And phosphorus is a central element in the complex process that allows your cells to breathe. Without them neither the ctenopoma nor anything around it exists.
But that’s not the case in any case. This rock goby lives in the Mar Menor (Murcia) and, although it does not know it yet, it will be one of the few survivors of the next hypoxia event in which the animal will be almost completely consumed in the water. The defect will also be strange to nitrogen and phosphorus. And this Mediterranean lake is the best example of how we have come to alter the cycles of two elements essential to life, to turn them into a problem for the planet – and for our species.
Ingredients for life (and agriculture)
Far from the Mar Menor, 1.5 million kilometers from Earth, floating in outer space, the new James Webb telescope caught the universe’s tracks. Among his many missions is to explore possible evidence of life on other planets. To do so, there are many techniques, but astrobiologists often focus on one: discovering the essential ingredients for life as we know it on Earth. That is, to detect carbon, hydrogen, oxygen, sulfur, nitrogen and phosphorus. Without these six elements, life on our planet is not possible.
Nitrogen is the most abundant element on Earth, making up 79% of the atmosphere. It is also present in all living things on the planet, since it is the key to the formation of DNA, amino acids and proteins and the transfer of energy. In fact, humans are about 3% nitrogen. However, while other organisms need to build with nitrogen, the one present in the atmosphere is very stable and difficult to combine. The path that follows to become part of the machine life is not exactly easy.
“Most animals need reactive nitrogen, combined with other elements. And the ability to transform nitrogen in the atmosphere into other compounds in natural systems is limited,” Estela Romero, marine ecologist and postdoctoral researcher at the Center for Ecological Research and Forestry Applications (CREAF) of the University of Barcelona. “Some bacteria can only do that, fix nitrogen and when hydrogen bond Some live in the soil, others are dissolved in the roots of plants such as vegetables, and many of them are even in the ocean.
From there it passes to other animals through the trophic chain. All of these pathways are known as the nitrogen cycle, a set of biological and chemical processes that work with this element throughout the biosphere. All the essential ingredients of life follow their own cycles, including phosphorus, although with one small difference: it is much less abundant than nitrogen. It is barely present in the atmosphere to begin with, and almost everything that exists on earth is in the form of rock.
This solid phosphorus, through erosion, over thousands and millions of years, passes into the earth, from there to plants and then to animals. Also a part is drawn to the rivers and the sea, where all the animals catch. “There is no life on earth that can function without phosphorus,” says Julia Martín-Ortega, professor of ecological economics and associate director of the water research center at the University of Leeds. “It is key to the functioning of the basic structures of the cell.”
While they are two essential elements for living things to function, nitrogen and phosphorus are also two limiting factors for life. That is, if they are not in the middle, or if they are in small quantities, plants and animals cannot grow in the same way. This is something that the global food system, as designed, cannot provide. In the European Union alone, in 2020, 10 million tons of nitrogen will be fertilized and 1.2 million tons of phosphorus will be used to fertilize fields. But most of them did not stay with them, and this is where the problems begin.
Sahara tunnels and nitrogen factories
The preparation of phosphorus and nitrogen makes the stage for the growth of animals. The more they can be taken from the middle, the faster their progress will be. Naturally, both elements of the planet are not equally distributed, so people end up devising two ways to increase the amount where needed. Thus, nitrogen and phosphate fertilizers have been one of the main components of the strong growth of agricultural production in the last 60 years (through the so-called green revolution).
“Between the end of the 19th century and the beginning of the 20th century, Fritz Haber and Charles Bosch were able to synthesize ammonium from dinitrogen. [la molécula que está en la atmósfera] in an industrial process using high temperatures and pressures”, explains Estela Romero. High temperatures and pressures that can only be achieved by burning fossil fuels. Today, the production and use of synthetic nitrogen are responsible for 10.6% of greenhouse gas emissions related to agriculture and 2.1% of global emissions.
“Their solution was brilliant, which earned them the Nobel Prize, and opened the door to the creation of artificial nitrogen fertilizers and, with them, to the hope of curing world hunger,” adds Romero. “However, with the discovery of the Haber-Bosch process, we introduced huge amounts of reactive nitrogen onto the planet.” It improved our crop yields, yes, but also changed it in many other ways, leading to some serious consequences for the ecosystem.
Phosphorus cannot be combined. But they are dug up. 85% of other phosphate rock deposits in the world are spread over 5 regions: Mauritania, China, Egypt, Algeria and South Africa. Morocco alone holds about 70% of the reserves. Part of these, important in terms of export, is in the occupied and conflicted territory, in whose situation Spain has a lot to do: the Western Sahara. While the Saharawi people are attacking the exploitation of aid from Morocco, exports have not stopped increasing, as reported by the Western Sahara Resource Watch organization.
After the aid of the United States, first and Spain, more recently, to the Moroccan project of the Western Sahara (which, among other things, recognizes the government in the territory of Morocco), the activity around phosphates has multiplied. According to WSRW, last year the Moroccan government gave the green light to the construction of a new fertilizer production plant and a new terminal port in Western Sahara. India and Mexico are the major consumers of Moroccan phosphorus, followed by Turkey, Pakistan and various countries of the European Union, including Spain.
The conflict between our neighboring country and the former Spanish colony is just one of the examples of how phosphorus has become an element of geopolitical tensions in recent years. “The big problem is that we are putting much more fertilizer into the soil than the plant can absorb. A part stands on the ground, and the rest goes with the waters, and ends as far as the streams and the sea. Phosphorus is not toxic, but we generate an imbalance of nutrients that end up with toxic consequences”, explains Iulia Martín-Ortega.
From the Mar Menor to the rest of the earth
At CREAF, the impact of excess nitrogen and phosphorus on aquatic ecosystems has been studied for many years, an impact that is much more visible in river basins, where human activity is more intense and where the population is greater. They create organisms and ecosystems by adapting to live with the limits of both elements (above all, phosphorus). They learned to practice and recycle effectively. But, a few years ago, humans disturbed the chemical balance of the environment to such an extent that we exceeded the limits of the planetary stability of the nitrogen and phosphorus cycles.
“The excess of nitrogen assumes a modification of the ecosystem that affects us directly, due to the higher levels of nitrates in drinking water and its serious health effects, e.g. [el exceso de nitrógeno en el trigo se ha relacionado con la alta prevalencia de la celiaquía] and indirectly, due to greenhouse gas emissions linked to production and use, Estela Romero points out. The impact of nitrogen overabundances in ecosystems are widespread and, with large heads not moving, are a real problem in the growing number of ecosystems and for more and more people.
The excess of nitrogen causes, among other things, the exorbitant growth of algae, which consume oxygen from the water (giving episodes of hypoxia or anoxia, as experienced in the Mar Menor, which lead to the suffocation and death of other organisms); explosive growth of toxic algae (such as those that cause the closure of shellfish farms and other aquaculture farms); the emission of ammonium and other greenhouse gases directly from the earth; or by direct contamination of surface and underground fresh water.
The same thing happens with phosphorus; According to a study recently published by CREAF, the excess of this element fertilizes marine waters, altering the growth of algae and other microorganisms that are at the base of the food chain, but that this cannot be done in conditions of extreme abundance. the rest remain in that ecosystem.
What are we doing here?
Both researchers agree to take the first issue seriously and reduce the contribution of both elements to the environment. In nitrogen, for example, you can bet on other crops and agricultural practices or in the reunification of agriculture with livestock (manure is a natural source of nitrogen). As for phosphorus, efficiency can be increased (it is estimated that more than 60% of fertilizers are used in water) and even in some cases they stop being used in which cultivated lands have significant reserves after many years of use. .
“The biggest problem for us is that there is no knowledge of the magnitude of the problem or an articulated government”, concludes Julia Martín-Ortega, who participated in the development of the new British government to change the use of phosphate fertilizers in the land. A country that indicates, among other things, the importance for the outcome of science and innovation, but also for politics, economy or society and the involvement of communities. “For example, we have a conversation about carbon and greenhouse gases. The results are better or worse, but it is there. But it doesn’t seem to be a match. Look at the Mar Menor how much it costs to start talking about the matter seriously, “he adds. “We have an ecological risk, due to contamination due to excess phosphorus and a real food risk, because the supply of phosphorus is very vulnerable, it depends on a few countries, and one day it could be cut off or become so expensive that it is inaccessible to many countries”.
