Size range [µm]

3. Mass fraction Size range [µm] WSOC CHEMICAL CHARACTERIZATION Org. < DL

4. Distinguishing characteristics of primary and secondary organic components in marine aerosol • Leading authors: Stefano Decesari / Matteo Rinaldi • Participants: • ISAC • UoC • NUIG • UMIST? • UoB? • ???

5. WIOC Colloids SOA POA WSOC Outline POA: WIOC + WSOC WSOC MAILY SOA ISAC-1HNMR: MSA, amines, short chain aliphatic carbonyls and carboxyls ISAC-HPLC: Mono and di-carboxylic acids relevant, few HULIS UoC-1HNMR: short chain aliphatic carbonyls and carboxyls UoC-LC-MS: sulphate esters of hydroxycarboxylic acids PRIMARY CONTRIBUTION Less polar fraction of WSOC UoC-LC-MS: long-chain mono and poly-unsaturated fatty acids (of phytoplanktonic origin) similarities with WIOC NMR spectra Sugars? SOA from isoprene (under low NOx conditions) or POA (bubble bursting experiment)

6. Other contributions?

7. ISAC – 1HNMR in D2O Marine aerosol WSOC Seasonal evolution of WSOC functional group distribution Relevant contribution from oxigenated groups (H-C-C=): carbonyls and carboxyls Features attributable mainly to a SOA • Signals from heteroatom-bearing molecules: • MSA dominant during spring-summer • Alkylammonium ions (DMA+ e DEA+) H-C-O: signals from aliphatic alcohols (possibly carbohydrates) POA contribution?

8. UoC – 1HNMR in D2O Chemical characterization of the same extract injected in LC-MS Main contribution from short chain aliphatic acids (max C5), more consistent with the SOA evidenced by LC-MS than with POA. Secondary compounds dominate in the water soluble fraction.

9. ISAC – HPLC-TOC Main contributing species: Neutral-Basic compounds and low-molecular weight carboxylic acids (mono or di-acids); 20-30% of N-B are alkylammonium salts, a relevant fraction of the rest is alcohols (sugar-like compounds) Scarce contribution from HULIS

10. UoC – LC-MS • Two main peaks were identified: the first (Rt = 3.19) containing more polar compounds than the second (Rt = 6.14): Peak at Rt 3.19: sulphate esters of hydroxycarboxylic acids (from C6 to C11). These components are attributable to secondary sources (SOA). Peak at Rt 6.14: • C12-C30 alkanoic acids; • long chain mono and poly-unsaturated fatty acids (myristoleic acid (C14:1ω5), dehydroarachidonic acid) likely of phytoplanktonic origin (Cloern, 1996); • ω-oxo-C8-carboxylic acid, α,ω-C8-dicarboxylic acid and α,ω-C9-dicarboxylic acid (oxidation of unsaturated fatty acids); This peak contains compound that can be attributed to POA and processed POA.

11. ISAC – 1HNMR in TFA WIOC1HNMR spectrum: signals due to long hydrophobic aliphatic chains, that are consistent with the second class of compounds evidenced by the LC-MS: long chain mono- and poly-unsaturated fatty acids (POA). Similarities also with BB WIOCand sea-waterfine POC spectra;

12. Marine organics combined characterization technique 1HNMR in TFA WIOC Marine aerosol OC WSOC 1HNMR in D2O HPLC (anion exc.) -TOC Acidification (pH 2) Selective extraction of weak organic acids and polar compounds Retained and eluted with meOH 1HNMR in D2O COSY 2D 1H-NMR Lost: Strong acids (MSA) & amines LC-MS ISAC contribution UoC contribution

13. HPLC speciation of WSOC Main contributing species were neutral-basic compounds and low-molecular weight carboxylic acids (mono or di-acids) N-B can partially been explained with the presence of alkylammonium salts (~30%) and aliphatic alcohols Scarce contribution from HULIS