Pascal Tuarze
To General Public
ENVS*1020 F10 (01-06)
23/09/2010
Deep-Sea Oil Plume Enriches Indigenous Oil-degrading Bacteria (Primary)
Vs
Deepwater Oil Plume in Gulf Degraded by Microbes (Secondary)
I chose to do my blog on what is happening to the oil in the Gulf of Mexico. What I came up with was a news article that states that natural deep sea microbes degrade the hydrocarbons of oil. This is a great alternative to putting potentially harmful dispersants into the deep-sea where the effects have not been studied thoroughly.
First I will be determining the strength of claims in the report (primary source):
They claim: “Here, we report that the dispersed hydrocarbon plume stimulated deep-sea indigenous y-proteobacteria that are closely related to known petroleum-degraders.” (1)
To make this statement credible they would have to explain several aspects of their research such as what types of samples they tested, how they tested them and how they found they were similar. In the report, the researchers tested samples with the PhyloChip; a brand new technology. The PhyloChip is a DNA-based microarray which, according to researchers can detect up to 50 000 different types of bacteria. This is very crucial information that helps solidify their hypothesis. The direct quote taken from the report is: “In plume samples, PhyloChip analysis revealed 951 distinct bacterial taxa … but only 16 distinct taxa that were significantly enriched in the plume relative to non plume samples… nearly all these enriched taxa have representatives that are known to degrade hydrocarbons”. (1) This information I find incredibly important because the test shows us that microbes are indeed related to known petroleum degraders. In the given report, figures that are significant include the microbial cell densities and composition. The direct data from the report includes: “(5.51+or – 0.33*10^4 cells/ml) in the plume and (2.73+ or – 0.05*10^4 cells/ml) outside of the plume”.(1) These two densities are significantly different making their claim stronger; microbe’s densities and composition change when they come in contact with oil. This means that there is a reaction occurring when the microbes contact petroleum. I feel that the original claim has been supported with sufficient data to make it viable. I would choose not to reject this hypothesis, but there is a need for more samples and tests to be done to make it an even stronger claim.
There was an image portraying the microbe that changes when it comes in contact with hydrocarbons of the oil but would not load to blooger site. Description of picture found just below this paragraph.
Analysis with Berkeley Lab's phyloChip revealed the dominant microbe in the dispersed Gulf of Mexico oil plume was a new species, closely related to members of Oceanospirillales family. (Credit: Terry Hazen group) This Diagram shows that a new strain of microbe is formed when it comes in contact with oil
“At most locations where the plume was detected there was a slight decrease in oxygen concentration indicative of microbial respiration and oxygen consumption as would be expected if the hydrocarbons were being catabolised”. (1)
This statement is harder to “prove” because of variation of concentrations in the ocean. In the report the researchers discovered that the samples taken differed. “In the area of the oil plume the sample had a concentration of 59% of saturated oxygen, whereas they found a concentration of 67% outside of the plume area”. (1)This in itself is not a strong claim because there is the possibility that there is less oxygen in one part of the sea compared to another. The researchers back up their theory by mentioning that for these microbes to work at a fast rate, they need iron to catabolise hydrocarbons. Iron is not found in great quantity in salt water. I feel this is the reason there is not such a dramatic drop in oxygen concentration in the plume area. When there is a lack of a chemical in a reaction it slows down the reaction or limits it to a certain degree. According to the researchers, if there were an oil spill in deep fresh water the microbes would degrade hydrocarbons much quicker, due to the greater iron content. In the process they would also use a lot more oxygen. If these microbes use a great quantity of oxygen in the water it would create dead zones, where too much oxygen has been removed from the water to sustain life.
Secondly I will be determining the strength of claims in the News Article (secondary source):
“In addition, frequent episodic oil leaks from natural seeps in the Gulf seabed may have led to adaptations over long periods of time by the deep-sea microbial community that speed up hydrocarbon degradation rates in adaptations” (2)
This statement has not been tested in anyway; the researchers have just made a theory for the reason why the microbes are able to degrade oil. Their theory is that the microbes adapted over time because of previous contact to natural leaks. I feel this claim does make sense but does not have sufficient data to make it a strong claim.
“Results in the Science paper are based on the analysis of more than 200 samples collected from 17 deepwater sites between May 25 and June 2, 2010”(2)
In the news article they mention that the researchers are basing their calculations on samples from 17 deepwater sites across the Gulf of Mexico between 25 May 2010 and 2 June 2010. This holds true in the report it clearly states the same information that is presented in the news article, making the claim a strong one.
In conclusion about the strength of claims of both sources:
The Science News (secondary source) does not manipulate or seem to neglect facts from the report (primary source) so they are, in fact, quite similar. All the points that were described in detail in the report were condensed in the secondary source, but it still contained the important data. It seems as though there is no bias on the subject, which is uncommon in secondary sources due to emotion of the author rewriting the information to their own preference. In this case it seems as though the author of the news article is just duplicating and simplifying the information for the public.
The sources limitations:
The limitation of each source would be the lack of the research in the field of deep sea microbes degrading hydrocarbons. There has been a minimal amount of research done on the subject. In this particular research expedition they had approximately one week to take samples. They also had two teams on separate boats to collect data. I believe this not enough samples and could harm the validity of their research. Once they were at the lab they were able to take tests with top-of-the-line equipment such as the PhyloChip, thanks to the 500 million dollars “generously donated” by BP.
The format and language:
You could also compare the format and language between the primary source and the secondary source. The format alone of the news article makes it much more appealing to read due to the placement of the illustration and the font size. The report is very bland to look at with the illustrations in the middle of the document and with no font changes. The language is also different; in the news article the scientific terms are kept to a minimum, while in the report, all scientific terms and data are put in to solidify their hypothesis. It is apparent that they are written for two separate audiences. The news article is for the public who have an interest in what is going to happen to the oil in the Gulf. The report is for researchers in that field who accept that hypothesis and try to build on it or for those who try to reject it.
Conclusion
In conclusion, the claims are strong in both sources with very few exceptions in the news article. There is a limit to the source of information due to the lack of studies in that field; however they do have sufficient results to prove that microbes degrade hydrocarbons. Finally, the format and language between the two are, in turn, noticeably different. The report is meant for researchers who are up to date on all the terms and data and the news article is meant for the public.
Bibliography
Deepwater Oil Plume in Gulf Degraded by Microbes, Study Shows." Science Daily: News & Articles in Science, Health, Environment & Technology. Web. 24 Sept. 2010.
"Defining Primary and Secondary Sources - Toolkit - The Learning Centre - Library and Archives Canada." Defining Primary and Secondary Sources. Web. 20 Sept. 2010.
"Science Express." Deep-Sea Oil Plume Enriches Indigenous Oil-Degrading Bacteria. Web. 20 Sept. 2010.
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