12 April 2019 nicolas

Engine Oil, what a pollution !

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A sea of soil – “Une mer d’huile”

Even without being a sailor, everyone knows the expression “a sea of oil”: One thus characterizes the surface of the water of a sea, a lake or a pond which is perfectly flat, smooth as a mirror, because nothing disturbs its surface. This pictorial expression comes in fact from a very concrete observation known since the dawn of time by all the sailors of the world: The oil calms the sea.

mer d'huile

This immemorial knowledge is attested in the stories of Plutarch and Pline. The polymath Benjamin Franklin did not fail to make the link between these stories and his findings during a few boat trips during which he realized by himself the apparent calm of the sea surface stained by oil. He thus decided to carry out an experiment in 1763 in Clapham: he poured into a pond a teaspoon of oil which spread instantaneously on the 1/4 of the surface of this one. He repeated the experiment several times always with the same success as he poured the oil “downwind” and not “in the wind”. Emboldened by these successes and by some testimonies, he even imagined to develop the technique of spilling oil to the bow of the boats to enable them to face more easily strong seas and in particular to dock more easily. Nevertheless his experiments proved to be fruitless which will explain it himself because the oil simply makes it possible to reduce the effect of the wind on the water but does not have a significant impact on a wave already formed. Curiously he will miss a remarkable physical result that his compatriot Rayleigh will highlight a century later by reproducing the experience: the thickness of a layer of oil is 1nm! (1 nanometer).

Oil pollutes a lot … for a long long time

huile environnement

By taking up the data from Benjamin Franklin’s experiment we come to ¹:

" 1 liter of oil pollutes 1 km² of water "

This figure in itself is impressive but it becomes frankly frightening when we take into account the data of annual consumption of engine oil in France: 280 000 000 L (²)


" 1% non-recycled oil ~ 2,800,000 L in nature ~ 5x France size "

But even in a country quite “virtuous”, especially in times of crisis for the recycling sector due to the collapse of oil prices which undermines the economic model of the sector and taking into account the many drainages made off-grid, it is more likely to be 10% to 15% of the oil that escapes recycling, which corresponds to ( France data ) a volume of

28,000,000 L of non-recycled oil

hence, an area of 28 000 000 km² will be polluted! If we compare this to the surface of metropolitan France – 551 500 km², this amounts to saying that the annual pollution due to drain covers

50x France’s area

You tell me, not completely wrong, that no country is not covered with water and therefore the oil will not directly spread so on such a surface … yes but in practice the effect will nevertheless be profoundly disastrous: In fact, the oil will first percolate through our floors, soiling them irreparably, asphyxiating³ flora and fauna on its way in epic proportions

1 L of oil pollutes 1 m³ of soil

eau pure

And since the oil is very weakly biodegradable, pollution is likely to reach the water table (… if there is a water table and depending on the type of soil, the oil may remain stuck in the soil). Although the oil and the water are not miscible, there is always a little diffusion of the one in the other, or even in a minute dose (1 part for 1 000 000 000 – 1 billion!) it changes the taste and flavor of water and makes the water table unusable for very long years. So even with a much higher threshold of 1 part for 100,000 to 500,000, we come to

1 L of oil contaminated between 1,000 m³ to 5,000 m³ of water


" 1 L of oil pollutes 1,000,000 L of drinking water"

Since the oil is hardly oxidizable or biodegradable, this pollution will remain for hundreds of years! And diffusion through the soil is not immediate (from 1m per year to 10m depending on the soil), we will “pay” the cost for a long time …

1. ↑ A teaspoon ~ 2.5 cm³ – the polluted surface ~ 2 500 m² so we have 1 cm³ ⇔ 1 000m² hence 1 000cm³ = 1 l ⇔  1 km² = 1 000*1 000m²
2. ↑ Centre Professionnel des Lubrifiants, données 2016 – It is curious, moreover, that the data are published in tons and not in liters for a liquid!
3. ↑ used oils contain many toxicants for health, especially heavy metals, organic acids, phenols, phthalates and aromatic compounds including polycyclic aromatic hydrocarbons
4. ↑ Université de Picardie, DESS Qualité et Gestion de l’Eau – “Pollution et Dépollution des nappes d’eau souterraine, §3.6 Hydrocarbure”

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