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Relevant concentrations of dimethyl- and diethylammonium salts (DMA+ and DEA+) were measured in submicrometer marine aerosol collected over the North Atlantic during periods of high biological activity (HBA) in clean air masses (median concentration (minimum-maximum) = 26(6-56) ng m-3). Much lower concentrations were measured during periods of low biological activity (LBA): 1 (<0.4-20) ng m-3 and when polluted air masses were advected to the sampling site: 2 (<0.2-24) ng m-3. DMA+ and DEA+ are the most abundant organic species, second only to MSA, detected in fine marine particles representing on average 11% of the secondary organic aerosol (SOA) fraction and a dominant part (35% on average) of the water-soluble organic nitrogen (WSON). Several observations support the hypothesis that DMA+ and DEA+ have a biogenic oceanic source and are produced through the reaction of gaseous amines with sulfuric acid or acidic sulfates. Moreover, the water-soluble fraction of nascent marine aerosol particles produced by bubble-bursting experiments carried out in parallel to ambient aerosol sampling over the open ocean showed WSON, DMA+, and DEA+ concentrations always below the detection limit, thus excluding an important primary sea spray source. [ABSTRACT FROM AUTHOR]

This study presents the changes in dissolved sulfate concentration and isotope composition of Icelandic river waters between the peak of SO2 emissions in the United States and Europe and the present. Chloride concentration in Icelandic rivers has not changed much since 1972. The overall average change from 1972-1973 to 1996-2004 was -3%, indicating insignificant sea-salt contribution changes. More than 99% of the river-dissolved sulfur was in the form of sulfate. There are three main sources for dissolved sulfate in the rivers: rocks, sea-salts, and anthropogenic. Total dissolved sulfate, tdSO42-, and non-sea-salt sulfate, nssSO42-, decreased in all of the rivers from the early 1970s to 1996-2004. The percentage decrease varies from 13% to 65%. The decrease is smallest in rivers were there is considerable rock-derived dissolved SO42-. The overall average decrease was 39% for tdSO42- and 46% for nssSO42-. The anthropogenic sulfate fraction has declined making most of the river waters δ34S values of sulfate higher through time. The overall decline in river sulfate and increase in δ34S, while SO2 emissions from Iceland has been increasing, demonstrates the response of river chemistry in the remote North Atlantic to the decline in manmade emissions of SO2 in North America and Europe. [ABSTRACT FROM AUTHOR]