Thursday, September 23, 2010

Water Fleas can Convert Nitrates and Nitrites to Toxic Nitric Oxide


Toxicologists from the North Carolina State University recently released the results of a study that they conducted that alters many common beliefs about nitrates and nitrites. The Nation Science Foundation has posted a secondary source article in order to create interest and consciousness about the issue within the public. The secondary source article is based of the original primary source article that was posted on PLos One on August 27, 2010. The basis of the sources is that the toxicologists preformed a study that found that water fleas could convert nitrites and nitrates into toxic nitric oxide. The effects of nitric oxide have thus far been found to be extremely negative in the water fleas. This creates further questions about what are the implications of this for humans, other organisms, and ecosystems? There are many similarities and differences in the articles, which are due mainly to the restrictions created based on the type of source that they are, primary and secondary.

The two sources vary in many ways such as tone, structure, thoroughness and scientific language. First of all, the tones of the two sources were dissimilar due to the different purposes that each source was meant for. The scientific primary article is meant to alert the scientific community of the specific findings resulting from the study preformed. It leaves any opinions about what should be done with the subject matter up to the reader. In contrast the secondary source can be much less formal in their approach. This means that they can include opinions and stress certain subject matter to their liking to convey the point they wish to make to the reader. For instance, I could deduce that the author of the secondary source believes that fertilizers are the biggest concern, when talking about things that introduce nitrates and nitrites into water systems because fertilizers are the only source they mention (and include in their title). However, the primary source reveals that there are actually many other sources for the nitrates and nitrites to come from such as the manure from concentrated animal feed operations. Secondary sources can also include opinions from interviews with the author of the primary source. My secondary source did include quotations from one of the authors of the primary source, which clearly created a tone of genuine concern for the environment.

The structures of the two sources were also very different in that the primary source was strictly organized with multiple titles and subtitles to create a more lab format for the journal. The secondary source was much shorter and did not contain any subheadings. These differences are because the actual journal and the article written about it contained vastly different amounts of information. The journal is required to be extremely detailed and thorough in order to have credibility in the scientific community. There are countless differences in thoroughness between the two sources but one that I feel would have been beneficial to include in the secondary source is that the study was carried out on Drosophila S2 (which are insect cells from a fly) as well as the water fleas. I feel that including that the second test subject would make the public feel it is a greater issue if it is proven in two subjects rather than just one. Also, the secondary source lumps nitrates and nitrite completely as one, when in actual fact the study found that nitrites had significantly more severe consequences than nitrates. This doesn’t mean that nitrates aren’t bad, it would simply clarify for the reader that nitrites are a bigger problem that need to be dealt with. Lastly, I believe that the secondary source should have elaborated more on the negative reproduction effects found in the water fleas instead of mostly just the developmental effects. I believe they should have included the information from the primary study that less offspring were produced from female water fleas that were exposed to the nitric oxide. I think that this is important because it shows the reader that not only do underdeveloped features reduce the life expectancy of an organism and thus endangering the population, but also that there are less in the population to begin with making the survival of the few all the more important.

Lastly, the two sources vary in language, meaning that the primary source is displayed in much more scientific words than the secondary source. The difference makes the secondary source easy to read and understand. In contrast however, the primary source is extremely difficult to read and understand completely what is being said.

The two sources are also similar in a few ways. They both do a good job at presenting the severity of the problem by comparing the concentrations of nitrates and nitrites in actual water bodies (1 to 2 milligrams per litre of water) to the concentrations that effects were recorded at in the fleas (roughly .3 milligrams per litre). The primary source uses exact values from the tests and the secondary source uses rougher estimates from the interview but both show the reader that our current concentrations are high enough to do significant damage to populations that are effected by nitric oxide.

The conclusions of both sources leave the reader with different ideas about what the next step of action should be. The course of action suggested for each source is very appropriate for whom each source is directing their ideas to. The primary source suggests that the next step is to discover the mechanism by which nitrates and nitrites are converted to nitric oxide within the water flea’s body. This is very appropriate because it is directed at the scientific community and they are the ones with the capabilities to pursue this course of action. The secondary source’s conclusion attempts to lead the reader’s thoughts and actions towards ways to keep the chemicals out of the water system. This is also very suitable because, the readers have the possibility to look for things in their lifestyles they could change, which could set examples to possibly reduce the problem in the long run.

Refrence List:

Secondary Source:
"Fertilizer Chemicals Linked to Animal Developmental Woes." Us News. 2010. National Science Foundation. Web.22 September 2010.
from http://www.usnews.com/science/articles/2010/08/31/fertilizer-chemicals-linked-to-animal-developmental-woes.html

Primary Source:
Hannas BR, Das PC, Li H, LeBlanc GA (2010) Intracellular Conversion of Environmental Nitrate and Nitrite to Nitric Oxide with Resulting Developmental Toxicity to the Crustacean Daphnia magna. PLoS ONE 5(8): e12453.
doi:10.1371/journal.pone.0012453
from http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0012453

Photo:
Daphnia. Photograph. Encyclopædia Britannica Online. Web. 23 Sep. 2010
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By: Kate Robinson 0719523

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