And acid rain?

In 1963, dr. Gene Likens, a limnologist (student of inland water bodies), reviews samples from the recent rainy season at the Hubbard Brook Experimental Forest in New Hampshire, United States, an open-air laboratory for climatological studies. The samples revealed a worrying trend: acid levels up to a hundred times above normal. If the rain continues to fall on the same acid level, it could destroy the entire ecosystem within a few years, and the most worrying thing was that he had no idea what was causing this acid rain, as the phenomenon was called.

A raindrop is never just water, it can contain innumerable particles, mainly elements and chemical compounds that float in the air. Some like CO2 increase the acidity of the water but nothing compares to the acids caused by nitrogen oxides and sulfur dioxide (SO2). They occur naturally in the atmosphere as they are usually by-products of phenomena such as volcanic eruptions or electrical storms, but they have a fairly short lifespan; At least if they are not accompanied by the millions of tons that are dumped into the atmosphere by power plants, refineries and vehicles every year.

On the pH scale we use to measure acidity, where 1 is the most acidic and 7.5 is a neutral pH, a raindrop usually has a pH of 5.4. Likens’ samples had levels as low as 2.85 – each number represents 10 times higher acidity as it decreases – and even below 4.5 is enough to kill small animals. But the gases released by the burning of fossil fuels not only affect the large cities where they are produced, they can travel hundreds and hundreds of kilometers with the wind, and their presence invariably increases the acidity of precipitation in any ecosystem, at any distance.

It has extremely detrimental effects on forests, as it weakens the trunk and burns the leaves of the trees and virtually sterilizes the soil from microfauna and saprophytes that break down dead material into nutrients, resulting in deforestation in wilderness areas and a drastic decline in arable production. ground. In some places in China, it has even turned arid deserts into what were once forests on the outskirts of new cities sprouting over vast Chinese territory. In aquatic bodies, the accumulation of nitrogen oxides and SO2 rapidly reduces the populations of amphibians, crustaceans and fish. And while there are species that resist the acidification of their environment better than others, an unconnected ecosystem is rare, so everything that affects one species eventually affects many others, including non-aquatic animals, such as birds. .

In cities, high levels of nitrogen oxides and SO2 wreak havoc on the population, mainly respiratory diseases. In addition, these compounds produce ozone at low altitudes, which is also harmful when inhaled. Acid rain does not directly affect people, but it affects the infrastructure of cities, destroys the paint on vehicles and corrodes metal elements exposed to the elements, causing accidents and material losses. But where its effect is most evident in buildings, mainly the oldest, where it dissolves stone and masonry coverings, the characteristics of statues fade and stain the facades where they run to the drain and oxidize the pipes.

At the beginning of the millennium, the European Union launched a system of emission restrictions and trade, consisting of limiting the amount of particles that a power plant or industry could release into the atmosphere in the form of “credits” that they can buy and sell with other companies to increase the amount of emissions. The United States joined before 2010, and in those years they managed to reduce both the level of NO and SO2 in the atmosphere and reduce the acidification of rainfall. In Mexico, studies have been conducted on the feasibility of implementing a system like this without us knowing any decision in this regard. When consolidated and applied effectively, a system such as this can mitigate the damage caused not only to our environment but also to our historical and cultural heritage itself, which has been particularly affected in recent decades, even when in the depths of a jungle, as if to remind us that although no one talks about it, the acid rain continues here.

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Ramon Martinez Leyva


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He is a computer systems engineer. His areas of knowledge are technologies, science and the environment.

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