Archive for September, 2016

Science Makes Sense-Week 44:Chemistry and Social Justice-The story of Deepwater Horizon and BP:the legacy of oil

September 13, 2016

I look at Hillsborough Bay in Florida to see a placid water body and the seagulls screeching while the brown pelicans sit on the wooden pole perches. And I wonder…… if they could talk to me would they tell me what really happened to their families and the humans around them six years ago during that oil rig explosion?  What really lurks beneath the calm blue waters?

The Gulf of Mexico is known for its rich variety of flora and fauna and also a long coral reef.  Pulley Ridge, 150 miles west of Cape Sable, Florida,has the deepest coral reef in the U.S.  There is another coral reef 110 miles south of the Texas- Loiusiana border.  The whooping crane, the peregrine falcon,piping plover, brown pelican and even the bald eagle make their home here in the gulf.  The shrimp and  fish industry supplies most of our sea food.   There are also a variety of endangered species of whales found in these waters.(Ref.1)  The area is at the same time, also rich in fossil fuel deposits under water.  Off- shore oil rigs have become the way to keep drilling for more oil by those not willing to look for alternative/green sources for our energy needs.

Deepwater Horizon was the name of an ultra-deepwater semi-submersible off-shore oil rig owned by a company called Transocean and leased to BP from 2001.  On 20th April, 2010, while drilling at the Macondo Prospect, an explosion on the rig caused by a blowout killed 11 crew members, ignited a fireball visible from 40 miles away.  The resulting fire could not be extinguished and in the process of doing that, the rig sank, leaving the well gushing and causing the biggest oil spill in U.S. waters.(Ref.2)

Drilling for oil, especially oil that is deep under water, is considered an acrobatic feat.  The crew drills the pipe to hit the oil level and the deeper one goes, the greater is the pressure of oil and mostly methane gas.  The comparison is made with a giant bag of popcorn taken out of the microwave ready to be opened buried under 5,000 feet of ocean and 13,500 feet of earth.  Instead of ripping the bag open, you insert an 18,500- foot straw, actually a pipe and then place a thumb over the straw, so the contents do not explode.  The air in the bag contains methane, the popcorn is the crude oil while the thumb is the cement used to seal the hole. (Ref.3)  Managing the pressure at such depths to bring up the oil and gas mixture in a controlled manner is called well- control. Problems managing the pressures is called a kick , whereas, loss of well- control is called a blowout.(Ref.3)

Why did the blowout occur?  It was later learned that there had been no regular check-ups on backup switches to close the flow of  gas in case of any mal functions.  The oil rig was equipped with visual and auditory alarms to shut off gas which was methane,CH4. Unfortunately, since these alarms make too much noise in the early morning  they were deliberately shut off!(Ref.4)

Following the blowout, the oil kept gushing and BP tried to deal with it by the addition of a dispersant called Corexit so the oil could be dispersed over a larger area.(Ref.5) 

Having somewhat understood the way this disaster occurred and the steps taken by BP, let us look at the chemistry of the chemicals present in the oil rigs during the blowout and later the effects on the species living in and around the gulf area. The burning of the oil rig was due to the methane gas, CH4 that was present which is highly inflammable.  The release of such a large amount of methane gas also leads to the depletion of oxygen in the water and the consequent acidification of the water.   This results in the killing of marine life and all other life dependent on it.  In addition, crude oil contains VOCs which are volatile organic compounds like benzene, toluene and xylene.  Benzene is a known human carcinogen, while toluene and xylene cause nausea, vomiting and fatigue to name a few problems that can ultimately lead to long term health hazards like cancer and birth defects.   Crude oil also contains mercury, lead that are known toxins.  Polycyclic hydrocarbons, also known as PAHs are present in crude oil which contains over a hundred different forms of these hydrocarbons.  Again, they are very toxic and cause cancers in mammals and humans.  When crude oil sits on water or shore, its harmful effects can be carried by the wind and air as a toxic aerosol.  When oil coats the body of the animals in the water, including many birds, it limits its ability to feed, move or even reproduce.  It also harms the external and internal organs of the animals adversely.  In addition, the roots of plants and trees along the marshy grasslands near the gulf shore are killed by the presence of oil.  These plants and trees actually protect those coastal regions to a certain extent from strong hurricanes.  Add to that the immense loss in tourism due to oil washing up on the shores of the sandy beaches dotted all over this area.(Ref.6)

To try to counter the presence of oil, as already noted, BP added the dispersant, Corexit.  This may have hidden the presence of oil to observers, but the dispersing only spread it over a larger area.  The excessive amounts used were unprecedented and its effects are well documented 5 years after the spill in a GAP (Government Accountability Project)report.  More than a dozen whistle blowers were interviewed by GAP.  Here is a summary of the first-hand effect of the devastating impacts of the oil in the water and the subsequent Corexit usage.  The witnesses range from cleanup workers, fishermen, scientists, residents and a physician.

  1. BP syndrome: all GAP witnesses experienced severe health problems, starting with blood in urine, heart palpitations, skin lesions and skin burning leading to kidney and liver damage and respiratory and nervous system damage.
  2. Interviewees were very concerned about long-term results including reproductive damage, endocrine disruption and cancer.
  3. Blood test results revealed high levels of chemical exposure to Corexit and oil; the chemicals here are known to be carcinogens.
  4. Ecological problems: there is evidence of oil and oil debris even after the cleanup was done.  The oil-Corexit mixture has coated the Gulf seafloor and permeated the rich ecological web leading to barren seafloor, widespread damage to the coral reefs.
  5. Majority of fishermen reported that their fish/ sea species had deformities and their catch had decreased substantially after the spill in 2010.(Ref.7)

In conclusion, I have to state that this is a much bigger problem than just BP’s bottom line on profits and gross negligence.  So long as we are dependent on big oil and continue to obtain our energy resources from the fossil fuel industry,we shall go along this slippery slope and destroy our fragile ecosystem and ultimately our lovely planet.

Activities for Middle School Teachers:

VOCs are present in all oil fields.  Students can look at VOCs and its usage in other industries besides oil rigs, e.g., in the paint/ varnish industry.  What safeguards are taken by workers when working with these aromatic compounds?

Students can do simple experiments adding oil to water and seeing how much detergent needs to be added to disperse it. What happens to the oil?  How does a detergent help disperse grease? (Instructor can introduce terms like hydrophilic and hydrophobic here, studying the structures of oil and detergents.) As the ratio of oil to water increases is there a critical point where the detergent is not effective? What other side effects would occur if the detergent is strong like Corexit?

Nuggets of Information:

The Gulf of Mexico has the most methane-rich production area and is also one of the most dangerous places to drill.(Ref.3)

Gas kicks are routine during oil drilling; even blowouts happen a lot of times.  From 1993-1998 there were 11 blowouts, and from 1999-2004 there were 20 blowouts in the Gulf of Mexico!(Ref.3)

Kemp’s Ridley Turtles were ready to be removed from the endangered species list, but thanks to the Deepwater Horizon disaster, they now are facing near extinction.(Ref.8)

Oil kills marshland directly and also poisons the complex mixture of algae, microbes in the soil.(Ref.8)

40% of the Gulf of Mexico’s federal waters were closed to fishing by early June 2010.(Ref.8)

Louisiana is the largest producer of shrimp and oysters in the nation and the second largest producer of crabs.  As a result of this oil rig disaster, the cost to the Louisiana fishing industry could total 2.5 billion dollars.(Ref.9)

A movie about this disaster called “Deepwater Horizon” is set to release soon.(Ref.10)

References:

1.Juhasz,Antonia, Black Tide,p.138 (John Wiley and Sons,2011)

2.deepwaterhorizon.com

3.Juhasz,Antonia, Black Tide,pp.10 ,11(John Wiley and Sons,2011)

4.Juhasz,Antonia, Black Tide,p.24 (John Wiley and Sons,2011)

5.Juhasz,Antonia, Black Tide,p.100 (John Wiley and Sons,2011)

6.Juhasz,Antonia, Black Tide,p.90 (John Wiley and Sons,2011)

7.whistleblower.org/gulftruth

8.Juhasz,Antonia, Black Tide,pp.143-5 (John Wiley and Sons,2011)

9.Juhasz,Antonia, Black Tide,p.163 (John Wiley and Sons,2011)

10.m.imdb.com/title/tt1860357/

Science Makes Sense-Week43:Organic Chemistry-Starches, sugars, cellulose

September 7, 2016

As children, we were fascinated by travel and far-off destinations. We would implore our parents to take a trip around the world and the answer would invariably be:” We cannot afford it, money does not grow on trees!”  If I had studied science then, I could have smartly retorted,” Oh but it does! Money is made from paper and paper comes from trees!”

Starch and cellulose molecules are polysaccharides,which literally means ‘many sugars’. (Ref.1). Cellulose is a long chain of linked sugar molecules that gives wood its strength and is the main component of plant cell walls and the starting point for textiles and paper.(Ref.2)  Cellulose is a poly saccharide polymer with many glucose mono saccharide units (Ref.3) and so is starch.   What is the difference?  Now each glucose unit is joined by acetal linkages.   These acetal linkages are actually an oxygen atom, connecting each glucose unit, left after a reaction between an alcohol group,-OH,with an aldehyde ,CH=O group where the water molecule is removed. (Ref.1)  In cellulose the acetal linkages are beta linkages (acetal group in the upper position) while in starch these are alpha linkages (acetal group in the lower position).  This interesting variation in acetal linkages between starch and cellulose  results in major difference in digestibility in humans.  Humans cannot digest cellulose since they lack the enzymes needed to break the beta linkages, while they can easily  digest starch.  Animals such as cows,sheep, goats and termites  have symbiotic bacteria in their intestinal tract that breakdown cellulose.(Ref.3)

The structure of cellulose and starch vary because of the different acetal linkages as well.  The angles in the beta linkages makes the polysaccharide cellulose a linear chain.  Meanwhile the angles of the alpha acetal linkages in starch form a spiral like a coiled spring.(Ref.3)

These polysaccharides are abundant in nature and their main function is energy storage and are the components of cell walls. They are called mono-polymers because they yield only one type of monosaccharide,namely glucose, after hydrolysis. Hetero-polymers also exist in nature (namely those polysaccharides which yield many kinds of mono-saccharides upon hydrolysis) and include gum, pectin.(Ref.4)  

Polysaccharides are not sweet-tasting like mono or disaccharides. They are non- reducing carbohydrates and do not undergo mutarotation.(Ref.4)  What is mutarotation?  A monosaccharide like D- glucose has two stereo isomers that can co-exist because of change in specific rotation of the chiral compound (a compound that does not superimpose on its mirror image).  The two isomers are called alpha D-glucose and beta D- glucose respectively.  Both are cyclic compounds with one acetal group, 5 carbons, 5 hydroxyl groups (-OH).   In the alpha form, one of the -OH is in the lower position whereas in the beta form it is in the upper position.(Ref.5)

Uses of sugars, cellulose and starch:  these mono/ di and polysaccharides can also be broadly classified as carbohydrates, sources of energy.  Green plants manufacture sugars and most of it is used for plant metabolism and very little accumulates.  However many vegetables and trees are sources of commercial sugar.(SeeNuggets)  Cellulose is a complex carbohydrate and cotton, pure cellulose, is the starting point for artificial fibers.  When wood, also cellulose, is treated with concentrated acids and alkalis, the bond between wood fibers and the lignin ( which holds them together tightly) is broken.  These can be reorganized to form paper.  Treated with more chemicals this can lead to the production of artificial fibers and cellulose plastics.  If you further break it down to the individual elements of carbon, C, hydrogen,H, and oxygen,O, (which is the fundamental elements in cellulose) these elements  can be recombined to form wood sugar, yeast and alcohol.  These are the raw materials for many industrial products.(Ref.6)

From time immemorial, we humans have depended on starch, cellulose and sugar for our energy intake, today we have broadened its usage considerably.

Activities for Middle School Teachers:

Construct molecules with acetal or hydroxyl linkages.  What changes in structures are observed with alpha or beta linkages? Where do you see stereo isomerism? Why or why not? (Remember the lack of rotation in the poly saccharides like cellulose and starch)

Students will look at the timeline for cotton production in the U.S. and other countries.  What was the impact of slavery on cotton productions?  How long did the production of cotton depend on African American labor even after slavery was dismantled?  As students study the structure of cellulose, let them study the history of  cotton production here in the US.

Look at potato, a common starch source for the western world. How were the Irish affected by the potato blight?  How did it change the demographics in the U.S.?

Nuggets of Information:

Cotton is the purest form of cellulose.  In the laboratory, ashless filter paper is, for all practical purposes,a source of pure cellulose.(Ref.2) 

Sucrose or table sugar is the most familiar disaccharide made by linking fructose and glucose.(Ref.2)

The length of the cellulose chain varies greatly: a few 100 sugar units in wood pulp to 6000 units  for cotton! (Ref.3)

Linking just two sugars produces a disaccharide called cellobiose, whereas cellulose is a polysaccharide produced by linking additional sugars in the same way.(Ref.3)

Storage sugars are found in roots of plants like beets, carrots and in stems of plants like sugar cane, sorghum and in flowers such as palm sugar and sugar maple.(Ref.6)

Maize/Indian corn is the source of 80% of the starch made in the U.S., while Europe is the principal producer of potato starch.(Ref.6)

References:

1.education.seattlepi.com/chemical-composition-starch

2.antoine.frostburg.edu/chem/Sienese/101/consumer/far/what-is-cellulose

3. chemistryelmhurst.edu/vchembook/547cellulose.html

4.chemwiki.ucdavis.edu/Textbook_Maps/Organic_Chemistry_Textbook_html

5. ochempal.org/index.php/alphabetical/m-n/mutarotation/

6.faculty.ucr.edu ( look for sugars,starch and cellulose)