# Possible Missing Sources of Atmospheric Glyoxal Part I: Phospholipid Oxidation from Marine Algae
## 2 Experimental Design  
### Investigation into Marine Aerosol Chemistry and Transfer Science (IMPACTS)  
A natural phytoplankton bloom was initiated on 3 July 2014, in a highly collaborative, month long wave channel experiment, Investigation into Marine Aerosol Chemistry and Transfer Science (IMPACTS). Approximately 13,000 L of seawater was transported from the pumping station approximately 5 m below the sea surface at the Scripps Institution of Oceanography (SIO) pier in La Jolla, CA, USA (32\({}^{\circ}\)51\({}^{\prime}\)56.8\({}^{\prime\prime}\) N: 117\({}^{\circ}\)15\({}^{\prime}\)38.48\({}^{\prime\prime}\) W), filtered with a 50 \(\mu\)m mesh to remove debris and zooplankton, and added to a 33 m \(\times\) 0.5 m channel. Nutrients (Proline A and B, Aquatic Eco-Systems, Apopka, FL, USA) in an F/2 concentration and solutions of sodium metasilicate were added to the channel simultaneously with the seawater to ensure a well-mixed environment. A total of 9 \(\mu\)M sodium phosphate was also added on 25 July 2014. The channel was continuously illuminated in order to promote eukaryotic growth. Chlorophyll \(a\) measurements recorded by the Southern California Coastal Ocean Observing System's (SCCOOS, [[http://www.sccoos.org/](http://www.sccoos.org/)]([http://www.sccoos.org/](http://www.sccoos.org/))) (accessed on 30 June 2014) automated shore station located at the SIO pier confirms that the observed blooms within the wave channel (Figure S1a) were comparable in magnitude to those of the natural environment (Figure S1b). The open wave channel was retrofitted with an air filtration system to create a low background environment (Figure S2). The system can provide particle-free air to the headspace of the channel at an airflow velocity of 12.2 cm\(\cdot\)s\({}^{-1}\). In addition to removing the particulates, the air was scrubbed free of volatile organic compounds (VOCs), nitrogen, and sulfur oxides by passing the air through a four-stage filtration system (Hydrosil International). The filter system consisted of a prefilter, a 4-mm coal-based filter, a pellet-activated charcoal filter, and a potassium permanganate (KMnO\({}_{4}\)) filter (see [48] Supplemental Information). Nascent SSA were generated through the action of breaking waves [48], which, for the purpose of this manuscript, were collected daily for two 2-h periods (4 h total) at \(\sim\)1 L/min into an impinger containing \(\sim\)10 mL of 60 mg/mL \(o\)-phenylenediamine (\(o\)-PDA, Sigma P23938, St Louis, MI, USA) in 60% tetrahydrofuran (THF)/H\({}_{2}\)O (Figure S2).  
Derivatization of glyoxal to quinoxaline at room temperature (Figure 1a) stabilizes the molecule for analysis, which is an established technique for glyoxal as well as other dicarbonyls [49; 50; 51]. The mass collected in the impinger from the SSA was concentrated using manual solid phase extraction (Supelco Superclean ENVI-18 SPE, Sigma Aldrich57064, St Louis, MI, USA) in triplicate, washed with THF/H\({}_{2}\)O to remove unreacted derivativizing agent (because _o_-PDA and quinoxaline co-elute), and then eluted with several column volumes of acetonitrile (ACN). The ACN was removed under vacuum and the samples reconstituted in 500 \(\upmu\)L of ACN in preparation for gas chromatography mass spectrometry (GC/MS) analysis. Controls samples within the wave flume at the start of IMPACTS were not possible, given that the timing of the water collection that was pumped into the wave channel corresponded with a stage of the pre-existing natural phytoplankton bloom that was later understood and postulated to be the initiator of algae-derived glyoxal (see Section 3 Results and Discussion). As a substitute, a daily _o_-PDA-doped solid phase microextraction (SPME) fiber was exposed to the room where the sample preparation took place and was transported with the analysis fibers as a control. Additionally, a suite of SSA, SSML, and bulk measurements were made daily by collaborators to monitor the physical, chemical, and biological changes that occurred throughout the course of the channel experiment.