Despite all the efforts and progress made to deal with or limit pollution of water places, many water bodies remain victims of pollution around the world. The pollutants accumulating in these water bodies, known as POP for “Persistent Organic Pollutants”, represent a strong threat to humans, that is the top of the chain, through the consumption of infected products, but also for many other organisms in aquatic ecosystems.
Indeed, around 60% of water bodies in Europe, lakes, rivers, inflows, and coastal and groundwater, still fail to guarantee a minimum ecological status qualified as “good” set by the 2000 framework directive on water by the European Environment Agency (EEA).
What are the sources of Persistent Organic Pollutants?
Anthropogenic, industrial and agricultural discharges are the main contributors to the contamination of water resources by POPs. Many of these chemicals are included in the Stockholm Convention to restrict the international production of certain POPs, but they are still used and detected in nature.
Pesticides used in agriculture are among the most powerful and serious pollutants, and which spread through the air, seep through the soil to reach surface water bodies or flow with the wastewater dumped into lakes and rivers.
Among the most harmful pesticides are organochlorines (DDT), organophosphates, pyrethroids and carbamates.
The smoke and clouds covering the city sky are mainly composed of water and fine particles from the combustion of fossil fuels from coal power plants, exhaust and heating gases, etc; and ground-level ozone (a greenhouse gas composed of nitrogen oxides and volatile organic compounds).
We also speak of photochemical SMOG when a reaction takes place between the ultraviolet radiation of the sun and the fine particles which finally turn into ozone and an invisible toxic cloud.
The risks associated with Persistent Organic Pollutants
According to the World Health Organization, POPs bio-amplify throughout the food chain and bioaccumulate in organisms. Human exposure to persistent organic pollutants, even at low concentrations, can lead to the risk of cancer, reproductive disorders, birth defects, etc.
For aquatic ecosystems
Acidic rain, combined with the natural presence of phosphates, creates a nutrient imbalance. The result is an impoverishment of the biodiversity of aquatic ecosystems.
Studies have also shown that a wide range of fish are contaminated with one or more of the POPs. Eels in Europe, for example, have been analyzed along the urban route of the Tiber through the city of Rome. Analyzes have shown that in this species, the amounts of dioxin-like compounds largely exceed the maximum level.
The problem of POPs goes far beyond fish and aquatic organisms to threaten other organisms involved in the food chain such as birds. Numerous studies have shown that populations of birds, preferring lakes as habitat and food source, are recovering more slowly than other bird species. They also present possibilities of more frequent organic deformations, which can affect their beaks, legs, heads or eyes.
POPs accumulate in the tissues of wild animals throughout their lives, and mainly affect the brain to produce behavioral disturbances. The contamination could also be transmitted substantially to eggs and newly hatched chicks via maternal intake. This reality is of particular concern since it can undermine any pre-established conservation process for the survival of a specific population in the long term. Also, how many future generations can these contaminants be transferred to remains a key question.