Arxiu d'etiquetes: oil

Nature in times of war

The actual world  is in turmoil. News related to terrorism, drug trafficking, coups d’état,  refugees crisis or the numerous wars still present flood our screens day after day. And, in a completely understandable bias, the focus is almost exclusively on the people and countries involved. But (and it’s something I ask every time I watch the news) what happens to nature in these regions punished by violence? In this entry we review the most important armed conflicts nowadays and their consequences for the nature surrounding them.

INTRODUCTION

Any human action has repercussions on natural life, and even more wars, intrinsically destructive. A series of damages on the wildlife are associated with them such as deforestation, soil degradation, pollution or hunting, among many others. The first time we really became aware of the great impact of the wars on nature was in the Vietnam War. The US army, in its fight against an invisible enemy, threw more than 75 million liters of herbicides into the jungles, in order to defoliate the trees to find their enemies. However, despite partially achieving its objective (we all know how that war ended) nature was seriously damaged. A study carried out in Vietnam in the mid-1980s found that there were only 24 birds and 5 mammals in an area where there were previously between 145 and 170 birds and between 30 and 55 mammals.

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A Huey helicopter from the US military overhangs the jungles of Vietnam while ‘bathing’ them with orange agent. Agent Orange was a potent herbicide and defoliant used by the United States during the war to make more visible enemies hidden in the jungle. A single plane could defoliate tens of hectares in a single flight. The US government spent $ 60 million a year on Agent Orange. Source: Zmescience.

Other wars, such as the Civil War in Rwanda, apart from causing more than 500,000 deads and displacing more than 2 million of people, left the nature of the country in a state of absolute crisis. In the Akagera National Park, one of the most emblematic environments in the country, deforestation wreaked havoc: 200,000 of the 300,000 hectares of forest were lost in just 3 years, as well as 90% of large mammals.

But what is happening today? How are the wars of today affecting the survival of nature? Here we review the most important current conflicts and their difficult coexistence with the wildlife of the region.

Israeli-Palestinian Conflict (1948-present)

Although the last war between Israel and Palestine began in 2005, violence between the two countries has been present since the creation of the state of Israel. Thousands of people have been dead for decades, and millions have been displaced against their will. And, of course, nature has not come out unscathed.

One of the most famous cases occurred in 2006. The Israeli army bombarded two oil tanks near a power station in Jieh, Lebanon (where a terrorist group called Hezbollah was emplaced) causing a spill of 10,0000 and 15,000 cubic meters of oil in the Mediterranean sea. This black tide spread along 90 km of the coast of Lebanon, carrying the death with it. In addition, this phenomenon severely affected the habitat of the green turtle (Chelonia mydas) in one of the last well-preserved places that this species still had in the Mediterranean basis.

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The bombing of two oil tanks by the Israeli army left 80 km of the Lebanese coast as can be seen in the image. In 2014, the United Nations Assembly urged Israel to compensate Lebanon with $ 856.4 million for this environmental catastrophe. Source: hispantv.

However, in early 2016, images that would call even more international attention came to light: dozens of animals from the Gaza zoo appeared completely mummified after suffering a terrible agony and starving. It happened twice since the zoo opened in 2007, but the strongest famine took place in 2014, following a conflict between Israel and Hamas’s Palestinian forces. It is estimated that about 80 animals died because of famine, including crocodiles, tigers, baboons or porcupines. When rescue services were able to reach the zoo, only 15 animals remained alive, many of them with severe symptoms of malnutrition.

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The Gaza zoo became the World’s Worst Zoo due to the shocking images of mummified bodies as a result of the famine that caused the war. According to Abu Diab Oweida, the owner of the zoo, the bodies were mummified so that everyone could see that even the animals were affected by the war. Source: Dailymail.
caballos-muertos
The continuous bombing in the Gaza Strip cause numerous casualties, such as those of the horses in the picture. Unfortunately, the end of the conflict is still so far. Source: helpinganimalsingaza.

Second Congo War (1998-2003)

This war, also known as the Great War of Africa or the African World War, has caused the death of more than 5 million people since then, which has given it the dubious honor of being the deadliest armed conflict since The Second World War. Although the war officially ended in 2003 and there is an elected government since 2006, the Democratic Republic of the Congo lives in a state of instability typical of a country at war.

The guerrillas use the country’s many natural resources to obtain money so they can continue the war. And ivory is the most precious commodity, the one that produces the most benefits. That is why African elephant populations (Loxodonta africana) have been reduced by 90% since the beginning of the conflicts. Something worse has occurred to the northern white rhinoceros (Ceratotherium simum cottoni) a subspecies of the white rhinoceros. Its last specimens, 2 males and 2 females living in the Garamba National Park, are believed to have died between 2006 and 2008 at the hands of the guerrillas, causing the extinction of this subspecies.

gorila-de-montana
The mountain gorilla (Gorilla beringei beringei), with an estimated population of  only 700 individuals, lives almost exclusively in the Virunga Mountains, a territory shared by the Democratic Republic of Congo, Rwanda and Uganda. In the picture, a mountain gorilla killed by unknown causes in 2007. It is believed that the rangers were involved in his death. Source: The Guardian.

Bushmeat, or the food coming from wild animals, is another major problem stemming from the numerous military conflicts in the country. In the wake of extreme poverty, many villagers have been forced to hunt to survive. And the primates has been one of the most harmed groups. The populations of the great primates, once counted by millions, have been drastically reduced. It is believed that there are only 200,000 lowland gorillas, 100,000 chimpanzees and 10,000 bonobos in freedom.

bonobo-killed
Bonobos (Pan paniscus) are our closest relatives, and one of the most threatened animals in the Congo. It is endemic to this country, but is being heavily hunted for food and, more recently, to serve as a delicacy to the Asian market. Specimens such as it appears in the image can easily be found in the markets of Kinshasa and Brazzaville. Source. National Geographic.

Syrian Civil War (2011-present)

Undoubtedly, the most famous war at the moment. This conflict has killed more than 500,000 people and has caused one of the most important humanitarian crises of our time: it is estimated that there are more than 10 million of refugees because of the war. Those who have remained in Syria, have been displaced from the interior to the coastal zone, becoming a great threat to the forests of the region. According to Aroub Almasri, a Syrian government environmentalist, most people need food, electricity and fuel to cook and warm up, which has lead to clear the area’s forests, mostly in protected areas. Apart from the severe impact of deforestation, there are also a large number of fires that have been spreading throughout the region in recent times. A particularly affected area is the Fronlok forest on the border with Turkey. In these mountains the degree of endemism is high, and many species are at a serious risk of disappearing from the area, especially a type of oak, Quercus cerris, native to the region and which would begin to be threatened.

Due to the fragmentation of the habitat, it is believed that an iconic species of the Mediterranean zone and classified as critically endangered by IUCN has become extinct in Syria. It is the bald ibis (Geronticus eremita), a bird of which only 500 individuals remain and is present only in three countries: Morocco, Turkey and Syria. In spite of Syria‘s enormous effort to maintain a stable population in its territory, the war wiped out the last individuals of this species in the region. Only one individual of the species remains, a female named Zenobia, who was seen for the last time in Palmyra before ISIS troops entered the city.

ibis-eremita
It seems that the numerous efforts made by the Syrian government in the early years of the twenty-first century have been insufficient to save this iconic species from extinction. Formerly present in large parts of Europe (from Austria to the Iberian Peninsula) the bald ibis has the most important populations in Morocco, its last redoubt in the natural state. Source: New Scientist.

Second Libyan Civil War (2014-present)

After the first Libyan civil war, which ended with the fall of Colonel Gaddafi, the country entered into a spiral of violence sponsored by the numerous armed groups that control the country. The importation of meat from abroad has stopped, and the owners of sheep, goats and camels keep their animals as if they were gold because of shortages. Because of this, armed groups are heading to the south of the country, where anarchy prevails and there are a lot of wild animals to take advantage of.

One of the most harmed species has been the rhim gazelle (Gazella leptoceros), classified as threatened by IUCN and with its populations in decline. Ten years ago the population did not exceed several hundred individuals, and it is believed that today the situation is much worse.

slender-horned_gazelle_cincinnati_zoo
Rhim gazelle is native to North Africa, where there are less than 2,500 individuals. The militias use their meat to feed or sell it in the Libyan market, where it is scarce. Source: Creative Commons.

But the gazelles are not the only ones harmed by the banditry and impunity reigning in Libya. Large numbers of migratory birds, which have to cross the African country on their way to Europe, are slaughtered by hunters. In addition, the oases that they use to rest are being opened by the hunters, which causes that hundreds of cranes, ducks, herons and flamingos are annihilated without anyone can do anything.

In addition, the effect of the Libyan war on nature does not remain within its borders. In 2015, weapons from Libya were found near elephant corpses in Mali, a heavily threatened elephant subspecies. It is believed that the ivory of the Mali elephants is serving to finance the Libyan militias.

A slaughtered elephant is seen in Bambara-Maoude
Mali’s elephants are one of the only two populations of elephants living in the desert. The last air census (2007) revealed the presence of only 350 individuals in the country. In 2015, 80 elephant were hunted, so the forecasts are not at all flattering: scientists believe that the population will die out in 3 years. Source: Reuters.

The Colombian government against the FARC and other guerrillas (1964-2016)

Despite the peace agreement reached few months ago between the Colombian government and the FARC, both social and environmental wounds will take a long time to be closed. For a long time the militias have been financed largely from the money generated by illegal cocaine crops. Placed deep in the Colombian jungle, thousands of hectares of pristine forest have been cleared for the construction of laboratories and coca plantations. In addition, in an attempt to stop this type of illegal crops, the government fumigated extensive forest areas with glyphosate, a herbicide that, despite being considered harmless, caused the death of birds, small mammals and insects, what in turn left without sustenance the people who live on hunt. Another added problem is that illicit crops have spread to protected areas. Thus, according to a report by the National Parks of Colombia, FARC were present in 37 protected areas of the country, and 3791 hectares of coca plantations were also detected in there.

However, the illicit activity that most threatens Colombia’s nature is illegal mining, one of the most lucrative activities for armed groups. Not for less, since while 1 kg of coca is sold at about 4.3 million pesos, 1kg of gold is sold at 85 million pesos, about 20 times more. For this reason, large areas of jungle have been destroyed by backhoes to open gold (60%), coltan (25%), charcoal (10%) and tungsten (5%) mines. Deforestation resulting from illegal mining reaches unimaginable numbers: between 1990 and 2010, an average of 310,349 hectares of forest per year were deforested, that is, 6206.000 hectares in all that time, or what is the same, 5.4% of the Colombian surface.

mineria-ilegal2
Mercury and cyanide, highly contaminating metals, are used for the extraction of gold. It is estimated that about 200 tons of mercury go to Colombian rivers each year. This has caused, at least, the contamination oh 90 rivers, affecting the local fauna and flora. Source: Semana.

Finally, FARC actions against oil extraction have caused serious oil spills in areas of high environmental value. This is the case, for example, of the 492-liter oil spill in Puerto Asis, Putumayo, in June 2015. The FARC intercepted a convoy containing tanks with oil and spilled them, affecting 9 wetlands and spreading oil along the Putumayo River.

petroleo-derramado
In 2013, the FARC’s systematic attacks against the oil industry accounted for 132 only in the province of Putumayo. Hydrocarbons contaminate the soil and remain there for years. In water, oil, due to its oxygen consumption, creates anoxic conditions that causes the death of fish. Source: elcolombiano.

War in Afghanistan (2001-2014)

Either the last war and the previous one had a strong impact on the region’s wildlife. It is estimated that between 1990 and 2007, more than one-third of Afghanistan’s forests were cleared, either by refugees to use wood for cooking, fuel or construction, or by logging industries, which cut down the forests of the region with impunity.

Nevertheless, the news are more optimistic than would be expected of a country plunged into war for decades. Between 2006 and 2009, the first censuses since the 1970s were carried out in the province of Nuritán, with the help of trap cameras, the study of faeces and the realization of transects. The results were encouraging: 18 black bears, 280 porcupines and many red foxes, gray wolves, golden jackals, wildcats, palm civets and rhesus macaques were observed, and even the elusive snow leopard (Panthera uncia), concretely 3 distinct individuals.

leopardo-de-las-nieves
Photo-trapping cameras captured images of the elusive snow leopard in the rugged Afghan mountains. With no doubt, they are encouraging news for its conservation. Source: James Nava.

However, there are still threats for Afghan wildlife. The large number of bombs thrown during the years made a dent in the abundance of migratory birds. Many birds died directly from the impact of the bombs or poisoned when they came into contact with contaminated water. Others, however, varied their rute due to the bombing and no longer cross the country. This is the case of the Siberian crane (Grus leucogeranus), a species critically endangered by IUCN that has not been seen in Afghanistan since 1999. In addition, due to the war and the incipient Afghan economy, hundreds of hunters Are forced to catch live birds for subsequent smuggling into rich Arab countries. This has led to the fact that, in some regions of Afghanistan, migratory bird watching has declined by 85% since the start of the war.

afganistan-pajaros
According to the Afghanistan Environmental Protection director, every year around 5000 birds are hunted for contraband, especially in the regions of Syed Khel and Kohistan. Many of the Houwa bustards (Chlamydotes undulata) and different types of hawks are sent to rich Gulf countries to serve as pets. In the picture, Afghan hunters near their rudimentary cages. Source: focusingonwildlife.

Korean Conflict (1950-present)

The Korean Demilitarized Zone is the proof that even something as tragic as a war can bring positive consequences. In 1953, following the peace agreement by both countries, the Korean Demilitarized Zone, a strip of land 4 km wide and 250 km long that separates both countries, was created. The area, which has a strong military presence of about 2 million soldiers, has remained virtually unchanged and sparsely populated since then.

separacion-corea
The Demilitarized Zone of Korea, or DMZ, separates both countries thanks to a buffer zone 4 km wide. In this place, the leaders of both countries usually hold the infrequent and tense meetings. Source: Creative Commons.

The area is characterized by a great topographic richness and high variety of ecosystems, which allows it to contain a great diversity. Some scientific expeditions have documented more than 1,100 species of plants, 80 species of fish, 50 of mammals and hundreds of birds. In addition, it is a frequent stop for many species of migratory birds that head towards Mongolia, the Philippines or Australia.

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The area has a great diversity of flora and fauna. Deer, bears, wild boars and large numbers of birds inhabit the territory. It is even believed that it could contain some individuals of the siberian tiger, habitual inhabitant of the zone before the Japanese occupation of Korea. Source: BBC.

Recently, thanks to improved relations between the two countries, the area can be visited for only about 43 euros. In addition, due to its exceptional conservation status and high diversity, some campaigns are under way to turn the area into a protected area. One of these campaigns, the DMZ Forum, proposes to declare the area as World Heritage Site and World Park for Peace, in order to be able to protect it from a possible urban development on the day that peace between the two countries is reached.

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The area has received numerous supports to convert it into a nature reserve in order to protect it from a possible future exploitation. Among the personalities who have supported the plan are the former US President Bill Clinton and the CNN founder Ted Turner. Source: BBC.

REFERENCES

DeWeerdt, Sarah (January 2008). “War and the Environment”. World Wide Watch. 21
King, Jessie (8 July 2006). “Vietnamese wildlife still paying a high price for chemical warfare”. The Independent.
Kanyamibwa S (1998). Impact of war on conservation: Rwandan environment and wildlife in agony. Biodiversity and Conservation, 7: 1399-1406.
Cover picture: Earth in transition.

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Knowing fossils and their age

In All You Need Is Biology we often make reference to fossils to explain the past of living beings. But what is exactly a fossil and how is it formed? Which is the utility of fossils? Have you ever wondered how science knows the age of a fossil? Read on to find out!

WHAT IS A FOSSIL?

If you think of a fossil, surely the first thing that comes to your mind is a dinosaur bone or a petrified shell that you found in the forest, but a fossil is much more. Fossils are remnants (complete or partial) of  living beings that have lived in the past (thousands, millions of years) or traces of their activity that are preserved generally in sedimentary rocks. So, there are different types of fossils:

  • Petrified and permineralized fossils: are those corresponding to the classical definition of fossil in which organic or hollow parts are replaced with minerals (see next section). Its formation can leave internal or external molds in which the original material may disappear.

    cangrejo herradura, fósil, cosmocaixa, mireia querol rovira, horseshoe crab
    Petrified fossil of horseshoe crab and its footsteps. CosmoCaixa. Photo: Mireia Querol Rovira
  • Ichnofossils (trace fossils): traces of the activity of a living being that are recorded in the rock and give information about the behavior of the species. They may be changes in the environment (nests and other structures), traces (footprints), stools (coprolites -excrements-, eggs …) and other traces such as scratches, bites…
    Cosmocaixa, huevos, dinosaurio, nido, mireia querol rovira
    Dinosaur eggs (nest). CosmoCaixa. Photo: Mireia Querol Rovira

    coprolitos, cosmocaixa, excrementos fósiles, mireia querol rovira
    Coprolites, CosmoCaixa. Photo: Mireia Querol Rovira
  • Amber: fossilized resin of more than 20 million years old. The intermediate state of amber is called copal (less than 20 million years) old. The resin, before becoming amber can trap insects, arachnids, pollen… in this case is considered a double fossil.

    Pieza de ámbar a la lupa con insectos en su interior. CosmoCaixa. Foto: Mireia Querol Rovira
    Piece of amber with insects inside, CosmoCaixa. Photo: Mireia Querol Rovira
  • Chemical fossils: are fossil fuels like oil and coal, which are formed by the accumulation of organic matter at high pressures and temperatures along with the action of anaerobic bacteria (bacteria that don’t use oxygen for metabolism).
  • Subfossil: when the fossilization process is not completed the remains are known as subfossils. They don’t have more than 11,000 years old. This is the case of our recent ancestors (Chalcolithic).

    Ötzi a subfossil. It is Europe’s oldest natural mummy. He lived during the Chalcolithic (Copper Age) and died 5300 years ago. Photo: Wikimedia Commons
  • Living fossils: name given to today’s living organisms very similar to species extinct. The most famous case is the coelacanth, it was believed extinct for 65 million years until it was rediscovered in 1938, but there are other examples such as nautilus.

    ammonites, nautilus, cosmocaixa, fósil, mireia querol rovira
    Comparison between the shell of a current nautilus (left) with an ammonite of millions of years old (right). CosmoCaixa. Photo: Mireia Rovira Querol
  • Pseudofossils: are rock formations that seem remains of living beings, but in reality they are formed by geological processes. The best known case is pyrolusite dendrites that seem plants. 
Infiltraciones de priolusita en piedra calcárea. CosmoCaixa. Foto: Mireia Querol
Pirolusita infiltrations in limestone. CosmoCaixa. Photo: Mireia Querol

Obviously fossils became more common after the appearance of hard parts (shells, teeth, bones …), 543 million years ago (Cambrian Explosion). The fossil record prior to this period is very scarce. The oldes tknown fossils are stromatolites, rocks that still they exist today formed by the precipitation of calcium carbonate because of the activity of photosynthetic bacteria.

The science of fossils is Paleontology.

stromatolite, estromatòli, estromatolito, mireia querol rovira, fossil, fósil
Stromatolite 2,800 million years old, Australian Museum. Photo: Mireia Querol Rovira

HOW A FOSSIL IS FORMED?

The fossilization can occur in five ways:

  • Petrifaction: is the replacement of organic material by minerals from the remains of a living being buried. An exact copy of the body is obtained in stone. The first step of petrificationis  permineralizationthe pores of the body are filled with mineral but organic tissue is unchanged. It is the most common method of fossilized bones).
  • Gelling: the body becomes embedded in the ice and don’t suffer transformations .
  • Compression : the dead body is on a soft layer of soil, such as clay, and is covered by layers of sediment .
  • Inclusion : organisms trapped in amber, or petroleum .
  • Impression: organisms leave impressions in the mud and the trace is preserved until the clay hardens.
    Fossilization processes and resulting fossils. Unknown author

    UTILITY OF FOSSILS

  • Fossils give us information on how living things were in the past, resulting in evidence of the biological evolution and help to establish the lineages of living things today.
  • Allow analyzing of cyclical phenomena such as climate change, atmosphere-ocean dynamics and even orbital perturbations of the planets.
  • Those who are of a certain age can be use to date the rocks in where they are found (guide fossils).
  • They give information of geological processes such as the movement of the continents, the presence of ancient oceans, formation of mountains…
  • The chemical fossils are our main source of energy .
  • They give climate information from the past, for example, studying the growth of rings in fossilized trunks or deposition of organic matter in the glacial varves.
    mireia querol rovira, tronco fósil, xilópalo, AMNH
    Fossil trunks where growth rings are observed. American Museum of Natural History. Photo: Mireia Querol Rovira

    DATING FOSSILS

    To determine the age of fossils there are indirect methods (relative dating) and direct (absolute dating). As there is no perfect method and accuracy decreases with age, the sites are often dated with more than one technique.

    RELATIVE DATING

    The fossils are dated according to the context in which they are found, if they are associated with other fossils (guide fossils) or objects of known age and it depends on the stratum they are found.

    In geology, stratums are different levels of rocks that are ordered by their depth: according to stratigraphy, the oldest ones are found at greater depths, while the modern ones are more superficial, as the sediments have not had much time to deposit on the substrate. Obviously if there are geological disturbances dating would be wrong if there were only this method.

    stratigraphic chart fossils
    Stratigraphic timescale. Picture: Ray Troll

    ABSOLUTE DATING

    This methods are more accurate and are based on the physical characteristics of matter.

    RADIOMETRIC DATING

    They are based on the rate of decay of radioactive isotopes in rocks and fossils. Isotopes are atoms of the same element but with different number of neutrons in their nuclei. Radioactive isotopes are unstable, so they are transformed into a more stable ones at a rate known to scientists emitting radiation. Comparing the amount of unstable isotopes to stable in a sample, scientits can estimate the time that has elapsed since the fossil or rock formed.

    Carbon 14 cycle. Unknown author
    Carbon-14 cycle. Unknown author
  • Radiocarbon (Carbon-14): in living organisms, the relationship between C12 and C14 is constant, but when they die, this relationship changes: the uptake of C14 stops and decay with a descomposing rate of 5730 years. Knowing the difference between C12 and C14 of the sample, we can date when the organism died. The maximum limit of this method are 60,000 years, therefore only applies to recent fossils.
  • Aluminum 26-Beryllium 10: it has the same application as the C14, but has a much greater decaying period, allowing  datings up to 10 datings millions of years, and even up to 15 million years.
  • Potassium-Argon (40K/40Ar): is used to date rocks and volcanic ash older than than 10,000 years old. This was the method used to date the Laetoli footprints, the first traces of bipedalism of our lineage left by Australopithecus afarensis.
  • Uranium Series (Uranium-Thorium): various techniques with uranium isotopes. They are sed in mineral deposits in caves (speleothems) and in calcium carbonate materials (such as corals).
  • Calcium 41: allows to date bones in a time interval from 50,000 to 1,000,000 years .

PALEOMAGNETIC DATING

The magnetic north pole has changed throughout the history of Earth and its geographical coordinates are known in different geological eras.

Some minerals have magnetic properties and are directed towards the north magnetic pole when in aqueous suspension, for example clays. But when laid on the ground, they are fixed to the position that the north magnetic pole was at the time. If we look at what coordinates are oriented such minerals at the site, we can associate it with a particular time.

Deposición de partículas magnéticas orientadas hacia el polo norte magnético. Fuente: Understanding Earth, Press and Seiver, W.H. Freeman and Co.
Deposition of magnetic particles oriented towards the magnetic north pole. Source: Understanding Earth, Press and Seiver, W.H. Freeman and Co.

This dating is used on clay remains and as the magnetic north pole has been several times in the same geographical coordinates, you get more than one date. Depending on the context of the site, you may discard some dates to reach a final dating.

THERMOLUMINESCENCE DATING AND  OPTICALLY STIMULATED LUMINESCENCE (OSL)

Certain minerals (quartz, feldspar, calcite …) accumulate in its crystal structure changes due to radioactive decay of the environment. These changes are cumulative, continuous and time dependent to radiation exposure. When subjected to external stimuli, mineral emits light due to these changes. This luminescence is weak and distinct as apply heat (TL), visible light (OSL) or infrared (IRSL).

Fluorite's thermoluminescence. Photo: Mauswiesel
Fluorite’s thermoluminescence. Photo: Mauswiesel

Can be dated samples that were protected from sunlight and heat to more than 500 ° C, otherwise the “clock” is reset as the energy naturally releases.

ELECTRON PARAMAGNETIC RESONANCE (ESR)

The ESR (electro spin resonance) involves irradiating the sample and measuring the energy absorbed by the sample depending on the amount of natural radiation which it has been subjected during its history. It is a complex method which you can get more information here.

REFERENCES

Oil spill effects on marine environment

Oh the occasion of the accident of the Russian fishing boat called Oleg Naydenov close to Grand Canary (Spain), the article of this week is about the effects of petroleum on marine environment. Here, I am going to talk about the origin of the petroleum in the sea, which are the transformations that suffer and the effects on marine fauna and flora. 

INTRODUCTION

The accident of the Russian fishing boat called Oleg Naydenov off of Grand Canary, which has finished with its sinking, is causing the appearance of oil in an area of 12 square km. The reason is that it sank with more than 1,400 tonnes of oil, 30 of diesel oil and 65 more of lubricant.

ORIGIN OF HYDROCARBONS IN THE SEA

Despite oil tanker accidents have a huge impact in the media, they represent a small portion of the amount of hydrocarbons that get in the sea. In general terms, these are the main sources of petroleum in the sea:

  • Industrial discharges and urban dredging: 37%.
  • Boat’s operations: 33%.
  • Oil tanker accidents: 12%.
  • Atmosphere: 9%.
  • Natural sources: 7%.
  • Exploration and production of hydrocarbons: 2%.

Although this values can vary depending of the sources, in general they represent quite good the proportions. It has been estimated that, each year, are poured into the sea 3,800 millions of litres of hydrocarbon, equivalent to 1,500 Olympic pools.

HYDROCARBON TRANSFORMATIONS IN THE SEA

When hydrocarbons are spilled into the sea (accidentally or deliberately), their features and shape change. This changes are physical, chemical and biological. This are the mechanisms:

  1. Evaporation: it allows that certain substances of the hydrocarbons go to the atmosphere, reducing about 40% its volume just in the first day. In any case, the surrounding atmosphere will be flammable.
  2. Dispersion: it consists on the fragmentation of the oil patch into small drops. When these drops are small enough, they remain in suspension and they mix with water and favours the biodegradation and sedimentation.

    La dispersió del petroli té un efecte positiu, doncs (Foto extreta de Ecosfera)
    Oil dispersion is positive because it allows the biodegradation (Picture from Ecosfera)
  3. Emulsification: consists on the absorption of water so the hydrocarbon’s volume increases between 3 and 4 times. This hampers the oxidation and biodegradation.
  4. Solution: depending on the product’s composition, the water temperature and its agitation. Only the more volatile components can be dissolved.
  5. Oxidation: the effect of the oxidation can produce a compound that is easier or more difficult to degrade.
  6. Sedimentation: consists on the down vertical displacement of the hydrocarbon’s particles. Depending on its density (with respect to water), the size and the agitation of the sea.
  7. Biodegradation: consists on the elimination of hydrocarbons by living beings, like bacteria and fungus.

PETROLEUM’S EFFECTS ON MARINE ENVIRONMENT

As we have said in the beginning of the post, the main goal of this is to comment which are the effects of petroleum (and other hydrocarbons) on marine fauna and flora. Let’s start!

The effects of petroleum on fauna are wide due to the high diversity of marine organisms. The main effects on the marine biodiversity are:

  1. Direct contamination: petroleum sticks on feathers, fur and scales, what make difficult the thermal isolation, movements and other important functions. As a consequence, this kills fishes, marine mammals and birds.

    Els mamífers marins es veuen efectats per la contaminació per petroli (Foto de Channel Island)
    Marine mammals are effected by petroleum pollution (Picture from Channel Island)
  2. Modification of gas exchange: the petroleum sheet reduces the content of oxygen in the water, what produce the dead of the plankton and fishes, what produce the dead of the organisms that feed on them.
  3. Alteration of seafloor: when petroleum is placed over the seafloor kills and produce sublethal effects on benthonic flora and fauna.
  4. Intoxication: petroleum poisons marine fauna, soaking into its digestive system and its skin and mucosa. The result is, on the one hand, the dead for suffocation and genetic disruptions on fishes, molluscs, marine mammals, reptiles and birds; and, on the other hand, the intoxification of other organisms like humans when they feed on them.

    Només una quarta part de les aus marines contaminades arriben a terra, la resta moren (Foto de Marine Photobank, Creative Commons).
    Only a quarter part of the contaminated marine birds achieve the earth, the rest dead (Photo: Marine Photobank, Creative Commons).
  5. Increase of the infections: because petroleum produces a reduction of the resistance to infections. This is specially important in birds because when they clean the feathers theirself, they swallow petroleum, so they present sublethal concentrations.
  6. Negative effects on fertility, reproduction and propagation of fauna and flora.
  7. Modification of the behaviour.
  8. Destruction of food sources.
  9. Incorporation of cancerous substances on food webs. 
  10. Effects on the availability of light: we cannot forget that the petroleum patch in the sea surface produce an important reduction of light in the water column. This causes a reduction or elimination of photosynthesis, essential process for the maintenance of food webs because the algae growth depends on light, which is consumed by herbivorous (and so on) and produce an oxygen input into the water. Moreover, we have to take in consideration that algae communities are shelter for many larvae and youthful fishes.
  11. Marine communities alteration: at community level, there is a gradient of vulnerability of oil spills. From less to more vulnerability, the communities are: exposed cliffs, exposed rock platforms, fine sand beaches, middle to big sand beaches, exposed tidal planes, big sand beaches, gravel beaches, protected rocky beaches, protected tidal planes, marshlands and mangroves, subtidal seafloors of sand and gravel, mud subtidal seafloors, batial and abyssal seafloors, infralittoral and circalittoral seafloors and reef corals.

REFERENCES

  • Notes of the subject Ecotoxicology and marine pollution of the Master in Oceanography and Marine Environment Management of the University of Barcelona.
  • EmerCoast Coast. “Training on marine pollution risks. Environmental risks in the littoral and marine environments”.
  • Course”Marine Pollution” from EuroInnova.
  • Greenpeace (2012). Environmental impact of petroleum (Brochuere).

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