In the general sense of the term, pollution is a degradation of the environment through the introduction of materials not naturally present in this environment into the air, water or soil. Pollution generates imbalances.
By causing a more or less irreversible disruption of ecosystems, the pollutant phenomenon mainly results in the migration or extinction of endemic living species, the latter being too often unable to adapt to their new biophysical environment.
On a larger scale, pollution can have a direct impact on human health and the biosphere, as demonstrated by the global warming process, which causes profound climatic changes and results in previously unknown diseases.
Mostly anthropogenic, i.e. directly or indirectly related to human activities, pollution can occasionally result from natural phenomena, such as geological phenomena, under which we find volcanic eruptions or earthquakes.
In the maritime sense, the concept of pollution has been defined by UNESCO's International Oceanographic Commission as "the direct or indirect introduction of waste, substances or energies, including underwater sources of origin which has or may have adverse effects on living resources and marine ecosystems, with consequent loss of biodiversity, risks to human health, obstacles to maritime activities, including fishing, tourism and recreation, as well as other uses of the sea, alteration of water quality from the point of view of their use and reduction of the marine environment's amenity value ".
The man's progressive appropriation of the sea has become a major risk for the maritime environment, because all human activities are potentially liable to generate accidental or chronic pollution.
Commercial and recreational vessels, as well as offshore oil exploration or exploitation platforms, underwater gravel pits, dredging or construction sites, but also aquaculture facilities are without exception, are the sources of polluting discharges.
The valorization of marine activities, as a source of economic, energy or food wealth, therefore passes through the preservation of this particularly sensitive environment.
Examples of pollution or polluting sources:
- Increased transnational pollution such as oil spills.
- The exponential increase in sea freight.
- Over-fishing and pressure on fisheries' resources.
- Coastal industrial spills.
- The exponential development of seaside tourism and boating.
- The multiplication of offshore exploration programs.
The urgency of a concerted and homogenized international awareness and response is now of a vital concern, as demonstrated by the United Nations Global Assessment of the State of the Marine Environment and the Global International Waters Assessment Program.
– CHRONIC POLLUTION
Chronic pollution is directly related to human activities. Very little publicized, this type of pollution is particularly damaging to our environment. This may include the release of chemicals, toxic gases, or any non-degradable material or substance into the environment. These releases come from human consumption, industrialization, agriculture, research, tourism, land, air or water transport and urbanization among others.
According to the United Nations environmental program, more than 80% of marine pollution can be classified as terrigenous (from land erosion) and anthropogenic (from human activities). This observation results from the fact that these pollutants originate from a so-called drainage basin, ending in the marine environment via rivers, canals, rivers and lagoons.
A. Pollution by toxic waste
This is waste classified as hazardous and having a direct negative impact on the environment and human health. This waste includes some household waste, industrial or agricultural waste, radioactive waste and health care waste (biomedical waste). Whatever their origin and specificity, these must be entrusted to approved structures that can ensure their treatment and recycling.
Note that by extension, the packaging of these products even when they are empty is considered to be dangerous.
Toxic waste and polluting substances have four main origins.
- Polluting substances of industrial origin (dangerous industrial waste) correspond in a non-exhaustive way, with hydrocarbons, oils, heavy metals, solvents, acids, bases, ionic solutions and radionuclides.
- Pollutants of agricultural origin correspond to fertilizers, nutrients and pesticides widely used by intensive agriculture.
- Pollutants of urban origin come from runoff and chemical residues not retained by the treatment plants' filters.
- Pollutants of household origin include asbestos, solvents, batteries, neon lights, batteries, spray cans, drugs, paints, glues and varnishes.
According to UNESCO, every year between 300 and 500 million kilograms of heavy metals, toxic sludges, solvents and other waste are dumped into the seas of the world by industrial and agricultural activities alone.
B. Pollution by macro-waste
It is all the solid and non-biodegradable pollutants generated by human activities.
These pollutants come from rivers, rivers, coastal emissaries, maritime traffic and the incivility of so many earthlings.
Among these macro-wastes are plastics, glass bottles, aluminum cans, cigarette butts, synthetic fabrics, rubber objects and fishing net residues; among others.
It should be noted that plastic waste, which accounts for more than 90% of the macro-waste recorded at the observation sites, is classified as one of the least biodegradable waste products, i.e. it takes between 100 and 500 years to decompose.
Ecological nuisances resulting from this type of pollution are particularly important on coastal and littoral ecosystems. Drifting plastics cause the death of large marine mammals by smothering (net residues) or intestinal obstruction (plastic packaging).
For man pollution's nature is mainly visual, with the coastline and tourist sites' aesthetic depreciation.
C. Pollution by non-toxic substances
The massive introduction of non-toxic substances into the marine environment may eventually constitute pollution, since these quantities exceed the capacity of assimilation of this environment. These may be large-scale coastal or offshore projects.
Thus, a massive concentration of suspended mineral particles, by abnormally increasing the turbidity of the water, can compromise or stop the complex process of photosynthesis essential for the development of aquatic flora and fauna and ultimately threaten the concerned area's global ecosystem.
In addition, the deposit of these mineral particles in thick layers on the seabed causes a phenomenon of depletion and desertification which is sometimes irreversible.
In another area, the massive indirect discharge of nitrates and phosphates at sea, can originate from deep imbalances generating complex phenomena including eutrophication. This phenomenon causes the appearance of algae or invasive microalgae, often toxic that destroy or entails the migration of endemic marine organisms and destabilize coastal tourism economies.
D. Pollution caused by plastic micro-fragments.
If all the seas of the world are exposed to the problem of visible macro-waste such as plastics (polyethylene, polypropylene), in July 2010 the MED (Mediterranean in danger) expedition, made up of a collective of European scientists and environmentalists, highlighted a worrying phenomenon of pollution which has gone unnoticed until now because of being virtually invisible.
The MED expedition carried out in the Mediterranean Sea (the phenomenon also concerns oceanic seas such as the Atlantic and the North Pacific) has been able to demonstrate by means of various samples, that under the combined action of natural factors which are the following: erosion, the salinity of seawater and the ultra-violet bombardment of the sun (which photo degrades the chains of polymers) the plastic macro-waste floating a few centimeters from the surface of the water eventually split up into thousands of micro-fragments.
From the samples taken in the neuston by the members of the expedition, it was established that the surface of the Mediterranean Sea would contain more than 250 billion of these micro-fragments resulting from the degradation of plastic bags and polystyrene-type waste. Measuring from a few microns to a few millimeters, the latter cannot be collected depending on their chemical composition and adjuvants used in their manufacturing process, rejected during the harmful toxic substances' fragmentation process.
At this stage, their environmental consequences are already considered to be objectively irreversible by experts:
- Ingested by turtles, birds or marine mammals, they can cause bowel obstruction or behavioral imbalances with fatal consequences.
- Their colonization by micro-organisms such as certain algae favor the development and proliferation of invasive species.
- Confused with plankton they are ingested indiscriminately by fish that are predation or fished, end up eventually consumed by humans at the end of the food chain.