Micropollutants: What Are These Molecules That Contaminate Our Water?
Today, our aquatic environments are polluted by numerous types of waste and chemical compounds. Some of these pollutants are invisible to the naked eye. These are known as micropollutants. They are chemical compounds found in aquatic environments at very low concentrations.
Geoffroy Duporté, University of Montpellier
By way of comparison, the minerals found in drinking water—such as calcium, potassium, and magnesium—are present in concentrations that are one thousand to one million times higher than those of a micropollutant.
The concentrations of these micropollutants are equivalent to a sugar cube in an Olympic-sized swimming pool. Obviously, if you take a sip, you won’t be able to taste the sweetness in the water, but unfortunately, even at these minuscule concentrations, some of these molecules can have negative effects on the environment, living organisms, and biodiversity due to their toxicity, persistence, and bioaccumulation.
Where do micropollutants come from?
There are many sources of micropollutants in the environment. Although some sources are natural (such as volcanoes, which emit large amounts of hydrocarbons), micropollutants are generally of human origin (industry, transportation, agriculture, and household use).
Currently, more than 100,000 molecules are classified as micropollutants by the European Union. A great many of the products we use every day contain them: cosmetics, medications, cleaning products, paints, and more.
The sources of water contamination by micropollutants are thus very diverse:
- Domestic wastewater plays a significant role in the transfer of these contaminants to aquatic environments. Although wastewater treatment plants are capable of removing some of these micropollutants, certain molecules enter aquatic environments without being removed. Drug residues (acetaminophen, antidepressants, etc.), phthalates (compounds derived from the use of plastics), parabens (found in cosmetics), UV filters in sunscreen, and pesticides such as antiparasitic products used on pets are examples of micropollutants commonly found in this domestic wastewater.
- Industrial wastewater also discharges numerous pollutants related to the activities in question (plastics, detergents, solvents, petroleum products, metals, etc.).
- Wastewater from hospitals also contributes to the contamination of wastewater with pharmaceutical residues. In particular, it contains numerous antibiotics, anticancer drugs, and contrast agents.
- Contaminants can also be of agricultural origin, such as soil pollution from pesticides or antibiotics administered to livestock. These micropollutants contribute to the contamination of aquatic environments through runoff or seepage.
This pollution finds its way into aquifers, streams, rivers, seas, and oceans. This invisible pollution thus also ends up in our drinking water supplies.
The fight against micropollutants is now a major environmental and public health issue. To illustrate this problem, a scientific study shows the widespread presence of pharmaceutical residues in 258 rivers around the world. The most commonly found compounds are carbamazepine (an antiepileptic), metformin (an antidiabetic), and caffeine. This study shows that at 25% of the sites studied, concentrations of at least one pharmaceutical residue exceeded levels known to have adverse effects on aquatic organisms.
For example, another scientific study assessed caffeine residues in aquatic environments as a contaminant of concern. This compound has been detected in the tissues of coastal and marine organisms (microalgae, coral reefs, mollusks, and fish). Furthermore, it has been shown that these caffeine residues can, for example, affect the reproduction and development of aquatic organisms.
This article is published as part of the “Questions from Youth to the Research ” initiative led by Agropolis International in partnership with the Montpellier Academy’s Office of the Superintendent of Schools.
If you have a question too, ask your parents to send an email to: . We'll find a scientist to answer your question.
Geoffroy Duporté, Associate Professor of Environmental Chemistry, University of Montpellier
This article is republished from The Conversation under a Creative Commons license. Readthe original article.