- What are the primary and secondary pollutants?
- Examples of primary pollutants
- Examples of secondary pollutants
We explain what pollutants are, and what are primary and secondary. Also, examples of both types of pollutants.
Carbon monoxide is released from motor vehicle exhausts.What are the primary and secondary pollutants?
Pollutants are called pure substances or compounds whose presence in the environment (Water, air, soil, etc.) deteriorates its quality, constituting a danger to the life as we know it.
Normally, a distinction is made between primary and secondary pollutants to differentiate between substances that are harmful to the environment. ecosystem that produce damage directly (primary) by being present in the environment, of which are formed indirectly through chemical reactions unforeseen in the environment, the result of the presence of other substances.
In other words, a primary pollutant is emitted directly to the environment, while a secondary pollutant is generated in it, as a consequence of present chemical reactions. Often they can go together, the primary and secondary, since the chemical reactions that the first produce usually have the secondary as a consequence, thus generating even more damage or during a longer period of time. weather.
Both primary and secondary pollution is one of the environmental challenges of the modern world, since its presence and its effects have increased since the emergence of the human industrial society, whose uncontrolled growth and energy needs, of raw material and complex chemicals leaves a significant toxic footprint on the world.
Examples of primary pollutants
Some examples of primary pollutants are:
- Carbon monoxide (CO). Produced by the combustion of fossil hydrocarbons, this highly toxic gas is released directly into the atmosphere by motor vehicle exhausts.
- Radioactive waste. The chemical products atomically unstable, such as plutonium resulting from the fission of uranium in power plants nuclear, have a long half-life during which they emit discharges of energy capable of altering the DNA of the living beings and cause disease.
- Sulfur oxides (SOx). Product of the chemical industry, these sulphated compounds are often discharged into lake waters and seas, where they modify the pH fluid and unbalance the nutrient count of certain microorganisms aquatic, which when supercharged proliferate excessively and break the balance of the food chain.
- Lead (Pb). The lead it is one of the main primary pollutants in water and air. This element is produced in the combustion of hydrocarbons and thrown into the air in the form of an aerosol (suspended solid particles), and thus pollutes the air and water, as it is washed away by the rain.
- Chlorofluorocarbonates (CFCs). These gaseous compounds were prevalent in aerosols and refrigeration systems, until the impact they had on air conditioning was discovered. ozone layer. Upon being released, you are mixtures of carbon, chlorine and fluorine whose half-life ranges between 50 and 100 years, react with oxygen in the atmosphere, destroying the unstable molecule of ozone (O3) and leaving us exposed to direct solar radiation.
Examples of secondary pollutants
Some examples of secondary contaminants are:
- Sulfuric acid (H2SO4). Product of the reaction in the atmosphere of water steam (H2O) and sulfur-rich gases discharged as an industrial by-product, this acid rushes to the ground along with the rain, forming what is called a "acid rain”And causing damage to the entire organic material that is exposed to it.
- Ozone (O3). Although in certain regions of the atmosphere ozone exists in a natural and harmless way, in other regions it can become a highly toxic and harmful element, which arises from photolysis of nitrogen oxides discharged into the atmosphere by heating and other systems. urban. The result, when these oxides come into contact with ultraviolet radiation, is the separation of their elements and the interruption of their degradation cycle, turning into ozone and free radicals, which form “photochemical smog”.
- Methane (CH4). In many cases, methane counts as a secondary pollutant, since it originates from the decomposition of organic matter, which is very abundant in garbage dumps or in rural livestock farming areas (from herd feces). This gas with a disgusting and highly flammable odor then rises to the atmosphere, where it accumulates, promoting the greenhouse effect.
- Peroxyacetylnitrate (PAN). This highly stinging compound for the eyes and lungs, and capable of damaging plants by prolonged exposure, is one of the main components of urban smog. It is produced from the decomposition in the air of volatile organic compounds, such as those used in paintings and liquid derivatives of Petroleum.
- Biological contamination. The excessive presence of nitrates and other fertilizers used in the agricultural industry in wastewater that eventually goes to the sea, introduces the Marine ecosystem an excess of nutrients that makes certain species of aquatic algae proliferate. Surpassing in population to their predators Natural, these algae proliferate disorderly and end up competing with each other and dying for tons, going to rot on the beaches.