Plastic waste in the oceans

Every second, 100 tonnes of waste from billions produced each year ends up at sea, a large part of which is made of plastic.

Some people call this the seventh continent, what a shame! Floating debris and or microparticles, this plastic waste is deposited on the beaches, dispersed at sea, found on the seabed. What effects do they have on humans and their environment?

Dispersal of this wasted plastic at sea has become a global problem for everyone. While polyvinyl chloride has a higher density than seawater and sinks immediately, the low density polyethylene microdebris remains on the surface.

It is estimated that 30 to 40,000 tonnes of microplastics float on the oceans and can travel long distances, sometimes thousands of kilometers from one continent to another, depending on currents, winds and tides.

A study carried out in 2014 estimated that, in total the entire pollution of the surface of the oceans is estimated at 5.250 billion particles, or 269,000 tonnes of plastics. It revealed that plastics and microplastics were present throughout the global ocean, anywhere and at any depth or any latitude.


In the early 2000s, alerts were launched by Greenpeace and other environmental organizations after the discovery of areas of accumulation of floating plastic waste, what some call the seventh continent.

For some experts, it is an abuse of language. The North Atlantic area, best known to scientists, reports only 1,100 tonnes of microplastics. In the North Pacific, the presence of microplastics is estimated at a few cm2 per hectare.

Plastic accumulation areas in the Mediterranean

There are however areas of accumulation, as in the Mediterranean, an area more exposed to marine litter due to its weak currents and tides, and significant urbanization and tourism.

Plastics there represent 70 to 80% of the waste observed on the coast, on the surface and on the seabed, with notable differences according to the zones: in certain gulfs of North Africa for example, fishermen manage to fish 50% waste and 50% fish! A clean sea, is it mission impossible? Maybe! People need to understand about litter at sea, and they may pollute less, while in the Gulf of Lion, they note a drop of 20 %.

In reality no study is currently complete enough to give answers on the global quantities of microplastics floating at sea in the world or of macro-waste on beaches or the seabed.

The densities on the bottom vary from 0 to 150,000 objects per km2 and the densities of microplastics vary on the surface from 0 to 900,000 objects per km2. The in situ degradation rates, estimated in the laboratory, are also poorly known.

And there is still a lot to discover on the accumulation of waste in abyssal pits where their degradation time is all the longer as there is a lack of light and oxygen.

it is sad to see how human development has led to such degradation of our seas, which after all are the cradle of life. We must stop this growth of plastic pollution before it is too late and the damage created by all this waste becomes irreversible.

What to do with your green waste?

Whether for individuals, businesses or communities, the maintenance of green spaces (gardens, parks, roadsides, etc.) produces a certain amount of plant waste called green waste.

100% biodegradable, this waste can still be cumbersome, so we have to find a way to eliminate it, if possible by exploiting the organic matter it contains.

Part of the waste can be left on site if it is not too large and the aesthetic aspect is not essential. They will then decompose gradually by providing shelter for the animals, feeding the fauna of the decomposers and then enriching the soil with organic matter.

If the volumes are larger, it is possible to compost the waste by gathering it in a heap in a corner or, if the region is suitable (weather conditions, absence of fire risk …), to burn it . The ash obtained, rich in mineral elements, forms a very good supplement for crops.

If it is not possible to compost or burn the waste on site (lack of space, authorization, too large volume), there are the recycling centers. There, green waste is recovered by composting, transformation into biogas or combustion.

Biodegradable, compostable, recyclable: the differences

In our daily life, what waste goes to the trash, to compost or to recycling?

What is biodegradable, compostable and recyclable waste?

The terms biodegradable, compostable and recyclable are sometimes used incorrectly. Sometimes also, by marketing experts, in order to sell us one product rather than another. What does biodegradable mean?

The term biodegradable applies to a product – organic matter – likely to decompose, in a favorable environment (conditions of temperature, humidity, light, oxygen, etc.) and under the action microorganisms (bacteria, fungi, algae). A biodegradable product decomposes without harmful effect on the environment. In doing so, it emits in particular water, carbon dioxide (C02) and or methane (CH4). So a banana simply left in the open degrades quickly. In an inert atmosphere, however, it keeps very well.

Another important criterion is time. Because for a product to deserve the qualifier of biodegradable, it is considered that its degradation must occur in a short time, with regard to human time. A dead leaf is thus biodegradable because it decomposes in a few weeks. A plastic bottle is considered non-biodegradable because it takes more than 400 years to decompose.

In the building, bio-based materials (wood, hemp, straw, etc.) are used, but these may have been processed and contain additives which make them non-biodegradable products.

In addition, note that a bio-based product – plastics in particular – is not necessarily biodegradable. Even if it is composed of generally vegetable substances, it can indeed contain non-biodegradable components. When we talk about biodegradation, we are looking at the end of life of a product. And when we talk about bio-sourcing, we are interested in the origin of materials.

Finally, be aware that ecosystems have a limited capacity to absorb biodegradable products. So even biodegradable materials can cause them damage if they are in too large quantities (eutrophication of the oceans).

Compostable and recyclable for new use

A compostable product is also biodegradable. But it is generally a product which is helped to decompose in an industrial unit. This is generally done at temperatures between 70 and 80 ° C, with a humidity level around 70% and an oxygen level of around 20%. After several weeks of (bio) degradation, we obtain a product, compost, allowing the improvement of soil fertility.

Note that in homemade composers, degradation is generally slower, because conditions, temperature and humidity in particular, vary with weather conditions.

Finally, a product is qualified as recyclable when it can, at the end of its life, be reintroduced into the production cycle in place of part or all of the new raw material, in principle useful for making a product. Glass is therefore typically not considered to be biodegradable. It is not compostable. However, glass is recyclable. As for whether it is recycled well in all circumstances, this is another question!