Off the French island of Oléron, the Stellamaris, the country's largest sand-carrying cargo ship, plunges a long, articulated arm into the Atlantic Ocean. In France, the exploitation of marine aggregates, primarily intended for concrete production, is highly regulated, but its environmental impact is debated.
For one to four hours, the round trips at a depth of 40 meters are made over the 1,3 km2 of the "Chassiron B" concession to pump a mixture of water and sediment.
"We vacuum everything to a depth of 20 to 30 cm and two meters wide. The impact is limited and acceptable," assures Frédéric Suire, environmental land manager in the Grand-Ouest region of the German company Heidelberg Materials, one of the main shipowners of sand-cargo ships in France.
The 4.200 tonnes of sand stored in the cargo ship's hoppers are unloaded at the port of La Rochelle.
"We are responding to a local need, within a catchment area of 30 to 50 km around the sand ports," emphasizes Laëtitia Paporé, director of this market for the German company.
In addition to concrete, aggregate (sand and gravel) of various sizes is also used for market gardening or beach replenishment.
Extraction represents only 2% of the 400 to 450 million tonnes used each year in France, mainly from land-based quarries and rivers, says Ms. Paporé, who chairs the marine aggregates commission of the National Union of Aggregate Producers (UNPG).
"Good student"
On the French coast, seventeen active concessions benefit from extraction permits for a period of 20 to 30 years, renewable.
This regulatory framework contrasts with other regions of the world, such as Asia or Africa, where "sand mafias" plunder the second most exploited resource after water.
Global consumption has exploded to reach 50 billion tonnes per year, three times more than all the sediment transported by the world's rivers (15 to 18 billion), according to Eric Chaumillon, a marine geology researcher, who points out that it takes "tens, even hundreds of thousands of years" to produce grains of sand.
In 2023, the United Nations Environment Programme (UNEP) warned about the conditions under which the six billion tonnes extracted from the oceans each year are extracted.
At sea, "the reserve is enormous, but we never exploit more than necessary," assures Frédéric Suire.
Extractors also point out that impact studies are mandatory every three to five years in France and highlight their monitoring programs.
The first results of a UNPG study on a former mining concession in the Bay of Seine highlight an "explosion in the return of flora and fauna 10 years after" its closure, according to Ms. Paporé.
Laure Simplet, a geologist at Ifremer, also indicates that no "risk to the coastline" is "detectable or measurable" on "all the sites" studied by the extractors, in partnership with Cerema, a public expert establishment on ecological transition.
According to her, France is even a "good student" with around three million m3 of aggregates extracted each year, no more than Belgium and its coastline of only 65 km3.
It does not allow screening of aggregates, a sorting technique which modifies the turbidity of the water, unlike in the United Kingdom or the Netherlands.
"Nonsense"
However, opposition led to the abandonment of extraction projects in Lannion Bay in 2022 and on the Matelier sandbank in 2019.
In the same area, the 20-year extension of the Platin de Grave marine deposit, operated by a subsidiary of Heidelberg between the Cordouan lighthouse, the Pointe du Verdon and Royan, is a source of tension.
In April 2023, the management board of the Gironde Estuary and Pertuis Sea Marine Natural Park voted in favor despite the unfavorable opinion of the estuary's scientific council and the French Office for Biodiversity within the Park. The prefecture must issue an opinion.
Daniel Delestre, president of the Sepanso association, which wants to have the exploitation declared invalid in court, denounces "ecological nonsense" in an estuary in poor health: "Fish species such as meagre, shad, and European sturgeon are threatened."
Sand, an essential resource that slips through our fingers
Sand extraction is a little-known but essential activity for human activity with major economic and environmental issues.
Five things to know about this abundant but limited resource in view of its rapidly growing use:
Extraction tripled in 20 years
Sand is, by volume, the most exploited natural resource in the world, after water: each year approximately 50 billion tons of sand, gravel and crushed rock are extracted or produced, according to the United Nations Environment Programme (UNEP).
"This is the equivalent of building a 27-meter-high and XNUMX-meter-wide wall along the equator every year," said UNEP data officer Pascal Peduzzi in Geneva.
Sand use has tripled in the past 20 years due to urbanization, population growth, economic growth and climate change, according to UNEP in its report "Sand and Sustainability: 10 Strategic Recommendations to Avoid a Crisis."
What is sand used for?
Sand and gravel are the basic raw materials for making concrete: there is more than a ton of sand and gravel in a cubic meter of concrete.
It takes 100 to 300 tonnes of sand and gravel to build a house and 30.000 tonnes to build a kilometre of motorway, as it is also the key element for making road surfacing.
It is also used to filter water in treatment plants or for land reclamation operations which involve reclaiming land from the sea.
Finally, it is a crucial material for industry: glass is made up of 70% sand. It is also used to make cosmetics and detergents, and is the basic element of silicone.
Where is sand extracted?
More than half of the sand used worldwide goes to the construction industry. Due to their physicochemical properties, desert sand grains, which are too smooth and round, are unsuitable for construction.
Saudi Arabia and the United Arab Emirates have had to import sand from Australia to carry out major infrastructure projects such as those in Dubai.
The majority of the sand used comes from land-based quarries, river beds, coastal exploitation on beaches or even extraction at sea using specialized vessels called "sand pits".
China and India, the two sand giants
China and India are the world's two largest producers of sand: out of an annual global production of sand (in the strict sense, excluding gravel and crushed stone) of around 12 billion tonnes, China extracts around 7 billion tonnes per year and India just under 300 billion tonnes. The world's third largest producer, the United States, has a production of less than 2018 million tonnes (XNUMX figures taken from the Belgian academic study "Mapping Global Sand").
In Europe, the main sand and gravel producing countries are Russia, Hungary, Germany, Poland and France (114 million tonnes), according to 2022 figures from the European industry association Aggregates Europe – UEPG.
Abundant but limited resource
Although sand may seem like an abundant resource, its exploitable quantities are limited in the face of rapidly growing global demand.
It takes thousands or even millions of years to produce beach sand, but today the level of extraction exceeds the rate of natural sand formation and replacement.
In some parts of the world, unbridled sand mining has already caused environmental disasters, such as in the Mekong Delta, where its uncontrolled exploitation has caused accelerated riverbank erosion. This is also the case on the Moroccan coast, where illegal sand extraction by traffickers has transformed beaches into rocky landscapes.
UNEP is calling for more effective regulations to preserve this "crucial resource" and for alternatives such as converting mine tailings into gravel and sand.
