Oceans worldwide are polluted by human-made chemical agents
Environment — di Andrea Barolini
A study published in Nature Geoscience points to a massive presence of pollutants in the oceans, with levels described as "enormous".
Oceans worldwide are polluted by human-made chemical agents
A study published in Nature Geoscience points to a massive presence of pollutants in the oceans, with levels described as "enormous".
Humanity has managed the far-from-edifying feat of polluting the seas across the entire world, everywhere, at every latitude. Confirmation has come from a study published by the journal Nature Geoscience, carried out by an international group of researchers and led by Jarmo Kalinski and Daniel Petra, biochemists at the University of California.
Synthetic chemical pollution makes up as much as 20% of dissolved organic matter in coastal waters, a meta-analysis of data from various marine ecosystems has found
go.nature.com/4uFjfl3
go.nature.com/4uFjfl3
The work carried out was particularly extensive: 2,315 seawater samples were collected from around twenty sites across the planet. The results show that chemical compounds originating from the agricultural, pharmaceutical and industrial sectors persist in the oceans, often in extremely high quantities, particularly in proximity to coastal areas.
248 anthropogenic agents found in the Pacific, Atlantic and Indian Oceans
"This study shows how few marine ecosystems remain in the world in which humans have not yet left their chemical footprint," Petras commented. To understand the state of health of the seas, the researchers did not aim to detect specific agents, but instead used a broad-spectrum method. This is the originality of the analysis, which made it possible to identify the presence of a total of 248 anthropogenic agents in the Pacific, the northern Atlantic and the Indian Ocean.
Their presence was confirmed in all of the samples collected, with a median value equal to 2 per cent of dissolved organic matter. Off coastlines, however, levels reached as high as 20 per cent, and in some cases extreme peaks of 63 per cent were recorded. Speaking to the French daily Le Monde, Richard Sempéré, oceanographer and director of the Ocean Sciences Institute at the University of Aix-Marseille, stressed that a value of 2 per cent is "far from negligible", while 20 per cent represents something "enormous".
Medicines, plastic additives, UV filters and insect repellents
The list contains everything: from insect repellents such as diethyltoluamide (known as Deet) and icaridin, to additives used in plastics such as phthalates. From UV filters used in sunscreens to surfactants. But numerous residues of medicines have also been found in seawater, from beta-blockers to antidepressants, through to chloroquine, a drug used to treat malaria.
"These are results that left me rather surprised, but which make absolute sense from a hydrological point of view. In Germany, for example, a significant portion of the water feeding the main rivers during the summer months comes from treatment plants. These plants, however, are currently unable to eliminate most organic compounds, which then end up in water bodies," Petras stated.
Pollutants could grow exponentially in the coming decades
Projections also indicate that pollutants linked to human activity will be increasingly present in the oceans in the future. A possible growth of 500–600 per cent is projected by 2050 compared to the start of the century. "This means that," Sempéré concludes, "we live in a world increasingly rich in chemical elements, many of which are toxic. We know that this is dangerous, that it entails impacts which are beginning to be observed and quantified. And yet, industry continues to produce them."