Water Water Everywhere

Walking up to the Hydraulics Lab for the start of each day of SeaSCAPE sampling is a truly awe-inspiring experience.  From the parking lot outside I have a breathtaking view over the endless misty extent of the Pacific Ocean; as soon as I walk through the doors I am greeted by the eerie breathing and hypnotic motion of the 30 m wave flume hard at work.  For a researcher who has previously focused on aerosols from forests, born and raised in the decidedly arid, landlocked state of Colorado, that is a disconcerting, and at times deeply frustrating, amount of water.  

My name is Emily and I am a graduate student researcher in the Goldstein Group at UC Berkeley.  I study the organic ‘goo’ that previous CAICE studies have observed coating salty sea spray particles during algal blooms.  Breaking waves cause tiny, salty droplets to be flung into the air, and in the presence of intense biological activity, many of these particles in the size range with the longest atmospheric lifetime become coated with an outer layer of carbon-based compounds from the microorganisms in the water.  The compounds in this coating can play a variety of different roles in aerosol fate and climate; they can alter how the aerosols interact with each other, how clouds form, and how light scatters from particles. My instrument is ‘offline’, meaning that instead of directly connecting to the wave tank itself, I collect particles on filters for analysis on an offsite instrument.  I do this by sucking air out of the wave flume just past the breaking wave, running it through a cyclone to screen out large droplets, then passing it through a filter which captures all of the tiny, salty, gooey particles. When I return to Berkeley, I will separate and identify the organic compounds in the particles using 2-D gas chromatography.

Being an offline sampler is an exercise in planning and delayed gratification- because my instrument is at home in Berkeley, I have no way to do preliminary checks on my samples and fine-tune my system.  All I can do is identify, mitigate, and document any potential sources of contamination, carefully design the sampling apparatus, and pay attention to any visual clues that something might be wrong. If I do everything right, the samples should, to the naked eye, be exquisitely boring.  Sea spray aerosols are generally white and so is the filter material, so they should look pretty much the same when I take them out as when I put them in. White is what I was hoping and expecting to see the first morning after the beginning of sampling- what I got was a sad and sodden grey.

The humid air coming off of the wave flume was condensing onto the insides of my metal sampling lines, collecting into droplets, and then hurtling through the sampler to soak my poor filters in a siege of tiny water balloons.  While I had anticipated that this was likely to be a problem and had built a short condenser, nothing I had tested it on prior to reaching CAICE was as humid as the wave flume and my system just wasn’t cutting it.  

In the grand scheme of things, a 47 cm water saturated filter is inconsequential.  In my world however, it spelled disaster. Wet filters do not collect aerosols in a uniform manner, and the compounds I am hoping to document can undergo reactions when they are dissolved in water.  What is more, my instrument back at Berkeley is quite sensitive (in both the scientific and, to my anthropomorphizing mind, emotional sense) and does not particularly appreciate having large amounts of salt water dumped into its internal workings. If I could not figure out a way to keep my filters dry, I would have no usable samples from the summer.   

Here I would like to take a moment to say thank you.  Thank you to my advisor Allen, our instrumentation consultant Nathan, and my mentor Lindsay for promptly answering my questions and guiding me from afar. With their advice, I swapped the 50 cm straight steel water condenser for a 3 m copper coil condenser, adjusted the slope of the collection area, added a heater to the lines, and achieved my first dry filters less than 48 hours into the campaign. Thank you to our lab manager Robin and my labmate Yutong for rushing to the rescue to overnight me the parts needed to put together the new system.  Thank you to Kathryn and Kathryn, to Jon, to Ryan, to Dan, to Brock, and to all of the others at CAICE who took time away from their own hectic schedules to offer advice, lend/look for equipment, or simply offer consolation and encouragement. When I imagined myself to be alone because I am the only CAICE student to call UC Berkeley home, I was very, very wrong.   

It would be nice to tie this anecdote up in a bow and say that with the addition of a big copper coil, all problems were solved.  However, that would be a lie. There have been a few more waterlogged filters, a few more late nights in the lab disconnecting, cleaning, drying, testing, and adjusting my setup.  As of this writing the filter collection has been successful with no water issues for nearly a week and I am cautiously confident that the current setup is ideal; then again, maybe I just jinxed myself.  What I do know for certain is that with each mishap I am learning more, panicking less, gaining confidence in myself, and deepening my appreciation for my collaborators, advisors, and H-lab friends. Most importantly, each dry filter sample collected is another tool to probe the composition of organics in sea spray aerosols in the months and years to come.

Written by: Emily Barnes, Graduate Student of Prof. Allen Goldstein at UC Berkeley

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).

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