Particle size versus Particle mass. (by Diego Fdez-Sevilla)


Particle size versus Particle mass. (by Diego Fdez-Sevilla)

“Hollow particles are common in the atmosphere, then instruments that measure particle size cannot be used to obtain particle mass (TSP)” was the comment by Roger J CHENG in a Linkedin discussion group “Air quality professionals”.

I have worked with airborne particle sampling methods and what I can share about it is that in Germany they used Glass fibre filters for two different analyses. One to measure Total Suspended Matter based on the weight of the filter, and the other one to measure Black Carbon concentrations based on measuring the optical absorption and scattering of light by the particles collected on the filter tape. Also, I worked for a while at the DWD in Freiburg looking for the best filter material suitable to perform these two methods plus, to use fluorescence and white light in order to identify pollen grains due to their synergistic effects on allergenic reactions when combined with pollutants (SO2, NO2, NH3 and VOCs). When using filters for particle sampling there is always a factor affecting the original state of the particles from when they were airborne which is the effect of having a constant current of air passing through the sample throughout the whole sampling period (which might be 24 hours). A combination of measuring particle size and particle weight might be closer to identify the role of each particle type in the total weight of the sample. When talking about reactivity, I believe that the method applied has to be defined based on the technique selected to analyze the sample. The process of particle sampling has to keep unaffected the properties in the particle that you want to measure, and I believe that is the challenge.

Just to add a little bit more, the challenges that I identified in my research about particle sampling started not only with the fact that the process of particle sampling has to keep unaffected the properties in the particle that you want to measure, but also, in order to have an accurate sample of particle concentration from your atmosphere it is very common to have a deviation from the real concentration due to sampling efficiency inaccuracies. The devices applied to capture by suction at the same time airborne particles of different sizes and shapes tend to overestimate or underestimate concentrations due to the different aerodynamic behaviour of the particles under the lack of isokinetic conditions (meaning that the air carrying particles into the sampling inlet has a different velocity of that the air carrying the particles in your environment). In my case, I studied those effects in sampling pollen grains. Pollen grains can take or release water when they are airborne (harmomegathy) so their aerodynamic behaviour changes with the environmental conditions which, altogether with the outdoors changing wind speed, affect the sampling efficiency of the instruments (also wind direction might become an issue if the device is not facing into the wind during sampling). With pollutants which might become part of crystals I suppose that parameters like humidity could also affect the measurements by the size of the crystal. Same with those particles which might react with others creating bigger or smaller structures. But that is just a guess.

Matters of discussion on LinkedIn are limited of participation to LinkedIn members or even just members of groups so, in order to reach as much contributors as I possible can I will share my take on those discussions I join in LinkedIn  also in this blog to enhance participation aiming to “fill in” or to “find out” relevant gaps.

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About Diego Fdez-Sevilla, PhD.

Citing This Site "Title", published online "Month"+"Year", retrieved on "Month""Day", "Year" from http://www.diegofdezsevilla.wordpress.com. By Diego Fdez-Sevilla, PhD. More guidance on citing this web as a source can be found at NASA webpage: http://solarsystem.nasa.gov/bibliography/citations#! DOIs can be generated on demand by request by email: d.fdezsevilla(at)gmail.com for those publications missing at the ResearchGate profile vinculated with this project. Author´s profile: Bachelor in General Biology, Masters degree "Licenciado" in Environmental Sciences (2001, Spain). PhD in Aerobiology (2007, UK). Lived, acquired training and worked in Spain, UK, Germany and Poland. I have shared the outcome from my previous work as scientific speaker in events held in those countries as well as in Switzerland and Finland. After couple of years performing research and working in institutions linked with environmental research and management, I find myself in a period of transition searching for a new position or funding to support my research. In the present competitive scenario, instead of just moving my cv and wait for my next opportunity to arrive, I have decided to invest also my energy and time in opening my own line of research showing what I am capable of. The value of the data and the original nature of the research presented in this blog has proved to be worthy of consideration by the scientific community as well as for publication in scientific journals. However, without a position as member of an institution, it becomes very challenging to be published. I hope that this handicap do not overshadow the value of my work and the intellectual rights represented by the license of attribution attached are respected and considered by the scientist involved in this line of research. Any comment and feedback aimed to be constructive is welcome. In this blog I publish pieces of research focused on addressing relevant environmental questions. Furthermore, I try to break the barrier that academic publications very often offer isolating scientific findings from the general public. In that way I address those topics which I am familiar with, thanks to my training in environmental research, making them available throughout my posts. (see "Framework and Timeline" for a complete index). At this moment, 2017, I am living in Spain with no affiliation attachments. Free to relocate geographically worldwide. If you feel that I could be a contribution to your institution, team and projects don´t hesitate in contact me at d.fdezsevilla (at) gmail.com or consult my profile at LinkedIn, ResearchGate and Academia.edu. Also, I'd appreciate information about any opportunity that you might know and believe it could match with my aptitudes. The conclusions and ideas expressed in each post as part of my own creativity are part of my Intellectual Portfolio and are protected by Intellectual Property Laws. Licensed under Creative Commons Attribution-NonCommercial conditions. In citing my work from this website, be sure to include the date of access. (c)Diego Fdez-Sevilla, PhD, 2017. Filling in or Finding Out the gaps around. Publication accessed 20YY-MM-DD at http://www.diegofdezsevilla.wordpress.com/
This entry was posted in Aerobiology, Aerosols, Filling in, Opinion, Polar vortex and Jet Stream, Water vapour and tagged , , , , , , , . Bookmark the permalink.

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