Thursday, September 23, 2010

A Very Simple Review of a Primary vs. Secondary Resource

In academics, literature is put into one of two categories, namely primary or secondary. Stated simply, primary literature is the findings of original research as written by the scientists themselves, whereas secondary literature can review and summarize original research, such as in literature reviews, newspaper articles and textbooks.

I reviewed an on-line news article authored by Harvard University entitled “’Archeologists of the Air’ Isolate Pristine Aersol Particles in the Amazon” which was based on a recent study, conducted on aerosols in the atmosphere. I then reviewed the original study authored by Poschl et al. (2010). There are distinct differences between the two articles which, I believe, stem from the parameters for each type of writing. These differences include; the audience, language and tone, as well as the style, layout, illustrations, and references.

Audience: Each article was written with a particular audience in mind. In the two pieces of literature I chose the titles alone demonstrate the divergence in the intended audience of the literature. The on-line news article reads “‘Archeologists of the Air’ Isolate Pristine Aerosol Particles in the Amazon”. Wow! I instantly had fantastical imagery run through my mind of a hot air balloon adventure over the rainforest canopy sucking up air with a vacuum complete with a safari hat. Putting aside the fact that I have no idea what pristine aerosol particles may be, this title holds a certain amount of excitement and promise. I for one have never heard of “Archeologists of the Air” and this catch phrase may entice me to read on. The primary research title reads “Rainforest Aerosols as Biogenic Nuclei of Clouds and Precipitation in the Amazon”. I will admit that this title peaks my interest but biogenic nuclei also alerts me to have my dictionary and google search at the ready. Although this title is accurate to the content of the article and indicates the who, what and where, it is less clear on what that all means.
Going back to the on-line news article’s title for a moment, what exactly did they mean by pristine aerosol particles? In the primary article, Poschl et al. (2010) uses terms such as “near-natural conditions”, “pristine tropical rainforest” and “pristine rainforest air” but never claims that the aerosol particles are themselves pristine.

Language: Secondary literature has a tendency to speak for a general audience. It may also flush out the main findings from original research and build a story around them which can potentially change the meaning or actual results published in the primary literature. For example, the primary article I reviewed explains that they were able to place the observed aerosol particles into five categories based on their origins, which are all named in the article. The secondary article focuses on the predominate source of the aerosol particles, namely secondary organic aerosol, and does not mention the other four sources. This omission does not necessarily change the meaning of the results but it does play into the articles earlier theme of pristine aerosol particles. The reality is that the aerosol particles were made up of more than the secondary organic aerosol so the reader of the secondary literature is not getting the full picture.

In the on-line news article the author communicates with common language though does use scientific terms where appropriate. When describing how the experiment was conducted they kept it very brief and said, “... using a range of techniques...”, in contrast, the primary article was more detailed in their description and said, “The measurement techniques applied include scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDX), atomic force microscopy (AFM), secondary ion mass spectrometry (NanoSIMS), aerosol mass spectrometry (AMS), differential mobility particle sizing (DMPS), ultraviolet aerodynamic particle sizing (UV-APS), and counting of cloud condensation nuclei (CCN) and ice nuclei (IN)...”. There is quite a dramatic difference in the information provided between the two articles. However, depending upon the audience, the message of the overall story is not necessarily lost by omitting the exact techniques used.

Tone: As a common reader who is not overly familiar with the topic of aerosol particles, through its tone, the on-line news article implied that this information is new, that it is something to get excited about and it has important consequences for our understanding of atmospheric processes and future understanding of climate change and the protection of the Amazon.
Where the on-line news article declares that “ “archeologists of the air” have, for the first time, isolated aerosol particles in near pristine pre-industrial conditions” the primary article states that “to our knowledge, this study provides the first comprehensive, detailed, and size-resolved account of the chemical composition, mixing state, CCN activity, and IN activity of particles in pristine rainforest air approximating pre-industrial conditions...”. The primary article is much more subdued in its approach, almost modest. As scientific research can never unequivocally prove anything, scientists are careful not to speak in terms of absolute truths when sharing their results for publication in scientific journals. The primary article takes a much more serious tone in the conclusion of the article “The feedback mechanisms involved may be important for stabilizing the Amazonian rainforest ecosystem and may also be generally relevant for the evolution of ecosystems and climate on global scales and in the Earth’s history.”

Layout and Style: For primary literature there is a certain layout and style you must adhere to depending on the literary journal you are submitting to. Some journals require a formal Abstract, Introduction, Materials/Methods, Results and Discussion, where others may include much of that information without clearly detailing the sections, and further, others may only make reference to supporting online material where you can find the materials and methods section as well as some of the more detailed results of the study. This is not necessarily the case for secondary literature. Though, there is an underlying framework and/or guidelines for the flow of the writing there can also be a greater degree of freedom when it comes to creative style in the writing.

Simple differences between the on-line article and the primary article are their use of illustrations and references. In secondary literature you can find images that are of general interest but in primary literature the only images seen are those directly related to the findings of the research. In the on-line news article an illustration of the observation tower used to collect atmospheric samples is displayed, whereas the illustrations in the primary article are of the types of particles observed and in the supplementary data there are tables of data collected. As well, in the on-line news article there are direct quotes from the scientists who conducted the research allowing for a simplified explanation, even a subjective perspective, of their research. Whereas, in the primary literature there are no direct quotes and the presenting of the findings is very objective.

In this particular case, although directed at two very different audiences, the two articles were indeed telling the same story adding or omitting some details.


Harvard University (2010, September 16). ‘Archeologists of the air’ isolate pristine aerosol particles in the Amazon. Science Daily. Retrieved September 17, 2010, from

International Global Atmospheric Chemistry Project. Image. Website accessed September 22, 2010.

Poschl, U., Martin, S.T., Sinha, B., Chen, Q., Gunthe, S.S., Huffman, J.A., Borrmann, S., Farmer, D.K., Garland, R.M., Helas, G., Jimenez, J.L., King, S.M., Manzi, A., Mikhailov, E., Pauliquevis, T., Petters, M.D., Prenni, A.J., Roldin, P., Rose, D., Schneider, J., Su, H., Zorn, S.R., Artaxo, P. and Andreae, M.O. 2010. Rainforest Aerosols as Biogenic Nuclei of Clouds and Precipitation in the Amazon. Science. 329:1513-1516.

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