Just the beginning in our quest to understand complex chemistry impacts on climate……

24 11 2011

As I sit here on Thanksgiving morning thinking of all I am thankful for, I think of many things but the CAICE intensive, just completed a little more than one week ago, keeps springing to mind.  We ran a few days longer than we expected, but on November 15, we officially stopped sampling with all instruments.

Due to the dedication of the team of scientists involved in this project, we took full advantage of the suite of measurements to run experiments 24/7 for the final 10 days.  In the final 5 days, thanks to input (and samples) from our biology colleagues, we ran a complete mesocosm experiment, studying how a mixture of bacteria, viruses, and other ocean critters affect the chemistry of the seawater and in turn, these changes affect the chemistry of sea spray.  Our experiments went from “simple” filtered seawater to single “critter” additions covering a range of properties to the full complexity of a real mesocosm bloom. We did all that we set out to do and more with many exciting surprises along the way.  I will say that the one thing that sticks out in my mind is how much easier it is to see instantaneous changes and make sense of the chemical complexity when you know for a fact you are looking at one source, in this case, sea spray.  This study has already helped our group explain critical observations we have seen countless times in field studies but never been able to explain.  It reinforces exactly why we moved the real world to the lab to perform complex chemistry experiments.  I think

Chemical complexity...the soup of bacteria, viruses, protozoa, organics, salts...formed some very interesting aerosols...

we will be able to clearly show how this represents a new approach for  “integrating reductionist and complexity approaches to solve complicated problems”, one of the grand NSF challenges we set out to address.

Everyone is recovering now, but feeling extremely rewarded by all we have accomplished as a collective group.  The fruits of all of our labor will become evident in the coming weeks and months, as we merge all we have found into one set of stories.  I want to personally thank everyone who has been involved in this study, Hlab staff, grad, undergrad, postdocs, faculty, and advisors, for your dedication to this CAICE project.

It has been a wonderful experience, one of the best of my 20 year career, working with everyone involved and I look forward to digging more deeply into the results together.  Today, I am thankful for all we were able to accomplish together–but I can’t help feeling that this is just the beginning of a long and productive scientific journey….

Here’s to hoping everyone has a wonderful Thanksgiving…

Kimberly A. Prather, Director of CAICE (http://caice.ucsd.edu)





A Unique Experience…

17 11 2011

As I sit down to write this I have just started draining the water from the tank one final time…what an experience the last few weeks have been.  I feel privileged to be the last non-professor to be able to write about my experience during the CAICE intensive for this blog, as in my opinion it is an honor to be able to write the concluding remarks for the group of fantastic undergraduates, graduates and postdocs that took part in this amazing study.  As such though, it is difficult trying to narrow in on one topic to write about from the countless possibilities that have arisen over the intensive.

The author, postdoc Tim Guasco (back, UCSD), is examining single particle mass spectra as they are produced in real time by ATOFMS.

Some of these include:

-What it was like being a postdoc in a field of science that is different from my PhD and trying to learn on the fly, while also teaching about things in which I have more experience than the rest of the group.

- I could also write about how enriching it was to not only be taking part in my first “field” campaign, but also to be part of the group who was tasked with getting the logistics right before the intensive started and be part of the day-to-day running of the experiments.

-Another potential topic might be how amazing it was to be able to take part in such an awesome study with people from not just around the country, but around the world.  There are few chances in most young scientific careers to be able to work in one place with such a diverse group of people.  I was able to learn quite a bit in a rather short amount of time because of the discussions I had with people who all approach the same problem with a slightly different mindset.

The list of topics could go on, however, I am going to focus on how a unique a collaboration this truly was.  In my opinion, large scale collaborations of this type are often overrated.  The idea generally put forth is that big problems in science are now too vast for a scientist from just one field to be tackling on his or her own.  To overcome this, a lot of really great scientists from all different areas and work to conquer the dilemma together.   While this seems like the perfect solution, often times it fails for a variety of different reasons.  These might be difficulty in finding the perfect person for the task at hand, or maybe finding that person but at an institution that is across the country, or also that sometimes other people are just hard to work with.  That might seem like a strange thing to read on a blog that is about a large collaboration, but these feelings of mine are precisely why I feel like the intensive campaign, and CAICE in general, are so unique.

It is very rare to be at a place where there are wonderful atmospheric chemists, physical oceanographers, amazing marine microbiologists, etc.  Also, let us not forget the  40 meter long wave channel that made this all possible.  At a place like this, you can literally walk down the street, see someone from a different field and talk to them about what is going on.  That person might then be able to provide a whole new perspective on the experimental setup and change things drastically for the better.  I know, because a chance encounter just like this happened when our fearless leader, Prof. Kim Prather, happened upon Prof. Farooq Azam from the Marine Biology division at SIO.  Prof. Azam was able to attend one of our daily meetings and his keen and unique insight set us on a completely different and far better course than was originally planned.  Given the one-of-a-kind setting and resources, the only thing that could have doomed us to failure would be conflicts of personality.  Luckily, everyone involved was so excited and proud to be a part of this intensive study that each and every person was willing to help out their fellow colleagues.  Therefore, I am calling this one of those rare large scale collaborations that is actually a success.  And the fact is, what people tend to say is true, the big problems in science in general are too vast for just one field, as such, when large scale collaborations of this type are successful, the knowledge gained is plentiful.  This study made me realize why people hold these collaborations in such high regards, the rare times they work, they are fantastic.

Tim Guasco, Postdoctoral Researcher, Prather Research Group, UC San Diego





Thoughts on Education in the Pursuit of ‘Big Science’

12 11 2011

Skip Pomeroy is taking the lead on the educational efforts of CAICE and organizing seawater analysis during the Intensive Campaign.

As the Intensive data collection period finishes its second week, I am struck by the dedication of the researchers and the interdisciplinary nature of the work.  Long hours are being logged.  The range of the instrumentation and techniques, both online and offline, is quite impressive as one enters the Hydraulics Lab.  I have yet to speak to anyone that doesn’t marvel at it a bit.  The interaction between the atmospheric scientists with the physical and biological oceanographers, the algae greenhouse staff, and the undergraduates and graduate students involved in the ocean water chemical analysis indicates the necessity of an interdisciplinary approach to solve complex chemical problems.  This observation then makes me reflect on a trend in our educational system of narrowing the breadth of the curriculum.  Starting with the query, do biologists need all that math or physics, or do biochemists need all of the physical chemistry, do atmospheric chemists need all of that wet chemistry — we have started to tailor the curriculum.  I think this works for some, but when I see the breadth of knowledge brought to bear by this group, I believe that a broad fundamental education creates the foundation upon which scientific inquiries like this can be supported.  I think the students and faculty engaged in this research have to be fearless when it comes to expanding their knowledge or skill sets.  Engineering, computer programming, electronics, fabrication (machining) are just some of the skills that these workers possess or are learning, over and above their expertise in their specific disciplines and areas of instrumental expertise. I am concluding it takes a broad range of people with a broad range of talents and the ability of these groups to successfully interact and communicate that leads to success in the pursuit of big science.

Skip Pomeroy, Department of Chemistry and Biochemistry, UC San Diego





It’s time to grow up!

12 11 2011

The author poses with the DASH-SP, which measures particle growth factors at different relative humidities in parallel.

I’m a second-year graduate student on my first field mission and this experience has definitely made me realize how intense the CAICE “Intensive” mission is! I’m in charge of operating the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP). The DASH-SP selects aerosol particles by size, splits the aerosol particles into several different channels, and exposes each channel to a different relative humidity. As a result of the humidification, the particles grow due to water uptake onto the particles, and their sizes are measured when they leave the channel. In summary, same-size particles go in, different-size particles come out (due to different relative humidities). The ratio between the size coming out after humidification and the size going in is called the growth factor. Growth factors can tell us how hydrophilic or hydrophobic particles are.

We’re interested in learning more about the properties of sea spray aerosol particles, especially when they are chemically affected by biology. Does the biology’s chemical influence make the sea spray aerosol particles more or less hydrophobic? As a result, do sea spray aerosol particles grow a lot or a little when the air is humid? The answer to these questions can help us in answering other questions about sea spray aerosol particles: How big do they get? How long do they stay in the atmosphere? How much light do they scatter? What does this mean for cloud formation? Ultimately, what does this mean for the Earth’s climate? Are there any feedbacks in the climate from our findings?

Growth factors for NaCl particles determined by the DASH-SP as a function of relative humidity. It’s expected that the sea spray aerosol particles will show similar growth factors to NaCl, but you never know! [Figure from Sorooshian et al. 2008, Aerosol Sci. and Technol.

I spent the previous month learning about the operation and troubleshooting of the DASH-SP. My research mentor and I had repaired and calibrated the instrument so that it was in perfect condition for the CAICE Intensive mission. When I learned I was going on my first field mission without my research mentor, I was afraid – very afraid! My only source of solace was that the instrument was in tip-top shape and that the field mission only involved turning the DASH-SP on and off every few hours. Little did I know that Murphy’s Law would be in full force for the DASH-SP – after a brief harrowing period of repair, the DASH-SP was back up and running again!

I’m very excited about what my measurements reveal about how sea spray aerosol particles, especially when chemically affected by biology, grow in response to different relative humidities. The true-to-life wave flume and the questions posed by the mission make it unique and will yield important insights on sea spray aerosol.

Wilton Mui, Graduate Student, Environmental Science and Engineering, Seinfeld Research Group, Caltech

The SIO Hydraulics Lab amidst the CAICE Intensive campaign.





What can we learn about atmospheric aerosols from this “Ocean in a Lab”?

11 11 2011

The author, Vicki Grassian, with postdoc Andy Ault, conferring about their sampling setup.

It is great to be here as part of the Center for Aerosol Impacts on Climate and the Environment (CAICE) intensive.  I visited this summer when some of the first measurements of the size distribution and size-resolved composition of sea spray aerosol were being made from the wave flume.  At that time, I was excited about the “ocean in the lab” setup to measure aerosol production from sea spray that Kim, Tim and their research groups along with experienced SIO scientists had achieved.  Now coming back for the intensive, I am even MORE excited about the possibilities of what can be learned from this highly unique opportunity for realistic measurements of the physicochemical properties of sea spray aerosol.  It is amazing to see all the different research groups and instruments that are involved in the intensive.  Some of these initial measurements show that the ocean generates a chemically diverse and complex mixture of components that depend on size and marine biogeochemistry.  This ocean mesocosm truly provides for an unprecedented opportunity to better understand the chemistry of sea spray aerosol.

Currently, there are on-line measurements being made of aerosol properties and off-line measurements of substrate deposited aerosols.  These off-line measurements allow us to further explore the chemistry and properties of sea spray aerosol with a wide variety of spectroscopic and microscopic probes.  Some of these off-line measurements are being done during the intensive, while others will be done after the intensive is over.  Dr. Defeng Zhao, postdoc at UCSD, has looked at some of these particles with Raman spectroscopy.  Some of the analysis of his data are straightforward for some inorganic components (e.g. the presence of CaSO4) but other data are more complex (e.g. some of the organics show very interesting spectra –perhaps amino acids?).  Today we will get together to brainstorm some more in analyzing some of these initial vibrational spectra of single particles generated from the wave flume. But even more is planned as Dr. Andrew Ault, a postdoc at the University of Iowa, has been part of setting up the intensive and will be bringing some of these samples back to Iowa for further analysis.

So after the last wave breaks and all the data are collected, assembled and further analyzed, I expect there to be MANY publications that arise providing insights into the chemistry of aerosols and their impact on climate and the environment that were not hitherto possible.

Vicki H. Grassian, F. Wendell Miller Professor of Chemistry, University of Iowa





Single Particle Microscopy and Spectroscopy

9 11 2011

The author (back) and Carly Ebben prepare to collect aerosols on microscopy substrates

Many of us can remember looking through a microscope at a young age and being amazed. All sorts of objects and biological “critters” jumped to life when tiny images that were blown up that we had no clue existed when viewing with the naked eye. This feeling is no doubt similar to what physicist Robert Hooke felt in 1665 when he first identified cells with a microscope. At the University of Iowa we use state-of-the-art microscopes and spectroscopic measurements to analyze aerosols at magnifications far beyond what Robert Hooke could have imagined, and we feel a similar sense of awe as we observe the structure and properties of aerosols with these extremely powerful and sensitive techniques.

A scanning electron microscope (SEM) image of a salt particle generated in our ocean-atmosphere chamber this summer.

The microscopy and spectroscopy measurements that we specialize in in the laboratory of Prof. Vicki Grassian at the University of Iowa are providing a unique view of the aerosols being generated during the intensive measurements at CAICE. Techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive x-ray spectrometry (EDX), Raman microscopy, atomic force microscopy, and x-ray photoelectron microscopy, are allowing use to probe the chemical and physical properties of these marine aerosols in extraordinary detail. For example, our TEM measurements can observe details on the scale of less than 1 nm (for reference that is 40,000 times smaller the diameter of a human hair). The black and what image of a particle from preliminary measurements this summer shows the fine detail that can be obtained for our marine particles (in this case a sea spray particle).

In addition to information on the structure of sea spray particles, we can also learn about the chemical composition from EDX combined with both SEM and TEM. The image on the left shows an image of a particle from SEM and on the right we have mapped out the chemical composition of different features with EDX. From this we can see that a sea salt particle isn’t just NaCl, but that the rods and other features contain mixed cation sulfates. This structure of primary NaCl cube and rods of sulfate species has been shown previously by Wise et al. 2007 for samples of resuspended sea water and field collected aerosols. The similarity of our wave flume generated sea spray during background measurements with previous field measurements shows that we are recreating the ocean well in the wave flume. With the background looking good we are excited to see what the biological species we are adding do to the chemical composition of the aerosols we are seeing!

At left, a traditional image of a salt particle as observed using electron microscopy. At right, the same image, with an overlay of chemical composition obtained using an x-ray spectroscopy technique.

Beyond electron microscopy, we are also excited to be working with ambient characterization techniques that don’t rely on introducing the aerosols to vacuum. Confocal Raman microscopy is one such tool we are utilizing to study aerosol properties as they exist in the atmosphere. The Raman spectra will give us information on organic carbon, sulfate, and other species with characteristic vibrations. Taken together the detailed morphology and chemistry of single particles from microscopy, Raman, and other will provide a great complement to many of the online measurements, in particular single particle size and chemistry from the aerosol time-of-flight mass spectrometer (ATOFMS).

Of course, this is just a sneak peek of the analysis we will be doing on aerosols from the wave flume. Expect more exciting results as soon as we get the samples back to Iowa!

Andrew Ault, Postdoctoral Scholar, Department of Chemistry, University of Iowa





Biological Material and Ice in the Atmosphere

8 11 2011

Paul DeMott (the author, Colorado State Univ.) had brought along his Continuous Flow Diffusion Chamber which measures how aerosol particles make ice crystals.

The few, the relatively unknown, but the powerful… I am talking about ice nuclei. These particles are special. How special? In air anywhere at any time, these can be the 1 in 100,000 to the 1 in 1 million of all particles. Ten ice nuclei in a liter of air is a relatively large number active particles at supercooled cloud temperatures. Measuring them is a special challenge, but that is what we are here to do – Ryan Sullivan (arrived yesterday to take over for me this week) and I.

Why do we care about particles present in such small numbers? Because it takes only a few ice nuclei per liter of air to initiate an ice-phase precipitation process efficient enough to lead to snow or rain at the surface.  If they transported in sufficient abundance to the upper troposphere, ice nuclei can alter the microphysical and optical properties of cirrus clouds. These particles are associated with some of the most uncertain indirect effects of aerosols on climate.

We know of the strong contribution of mineral and soil dusts as atmospheric ice nuclei. What about direct sources from the massive surfaces of Earth’s oceans? Sparse past data collected over oceans offer intriguing evidence that the oceanic source of ice nuclei can vary by orders of magnitude and may be linked closely to biological processes and biological organisms. The wave flume studies offer the opportunity to directly isolate the source of ice nuclei from sea spray particles (inorganic, organic, biological organisms?) as compared to air of unknown origin present in the oceanic boundary layer at any time, or as compared to what we know is in seawater.

Consequently, we are introducing particles into a flow through chamber that exposes them to conditions that they would encounter in clouds below 0 C, to measure their number concentrations in real-time. I have been surprised at the strength of the source from filtered seawater. We are collecting the activated nuclei onto electron microscopy grids for offline analyses of their elemental composition and morphology. Finally, we are collecting large volumes of air containing the particles for offline analyses of particle freezing spectra at the warmest temperatures below 0C where the real-time method loses sensitivity. My colleagues from the biological sciences, Drs. Tom Hill and Gary Franc of the University of Wyoming, will perform these measurements, as well as chemical and environmental sensitivity experiments to attempt to determine the relative contributions of bacteria, versus all biological, versus all organic particles to ice formation during the offline studies.

Who knows what other great ideas and collaborations will be spawned by the wonderful opportunity presented at this wave flume study?! We look forward to discussions with experimentalists and theoreticians alike.

Paul J. DeMott, Department of Atmospheric Science, Colorado State University








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