Climate warming affects the development and distribution of sea ice, but at present the evidence of polar ecosystem feedbacks on climate through changes in the atmosphere is sparse. By means of synergistic atmospheric and oceanic measurements in the Southern Ocean near Antarctica, we present evidence that the microbiota of sea ice and sea ice-influenced ocean are a previously unknown significant source of atmospheric organic nitrogen, including low molecular weight alkyl-amines. Given the keystone role of nitrogen compounds in aerosol formation, growth and neutralization, our findings call for greater chemical and source diversity in the modelling efforts linking the marine ecosystem to aerosol-mediated climate effects in the Southern Ocean.

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The methylamines form part of the marine organic nitrogen pool. Although they are ubiquitous in marine systems, little is known about their distribution, production, and fate in the marine environment. Analytical methods have been developed for their analysis in marine waters, but these have employed custom‐made apparatus, limiting data to a few studies. Here, we report a method developed for the determination of methylamines in seawater which combines headspace solid phase microextraction (SPME) and gas chromatography with selective nitrogen detection. Gaseous methylamines were pre‐concentrated from water samples (∼ 1 L) heated to 60 °C, onto a polydimethylsiloxane/divinylbenzene SPME fiber located in the headspace of the extraction flask. The analytes were then thermally desorbed from the fiber in a gas chromatograph containing a CP‐Volamine column and a nitrogen–phosphorus detector. The method was routinely calibrated down to 1 nM for all three analytes using matrix‐matched external standards. Limits of detection were determined operationally and ranged from 0.4 nM to 2.9 nM during two sampling campaigns. The analytes were detected in seawater samples from the English Channel and Southern Ocean where concentrations up to 20 nM and 5.6 nM were measured, respectively, consistent with previously reported levels. We propose this method for the analysis of methylamines, and other low‐molecular weight amines, as it is sensitive, robust, and the necessary equipment is widely available.

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