BASS Mesocosm Study: trace gas processes during a phytoplankton bloom with extreme slick formation

Short- and long-lived trace gases impact atmospheric chemistry and climate, via processes like hydroxyl radical chemistry, aerosol formation, cloud condensation nuclei formation, or the greenhouse effect. As the oceans serve as sources and sinks for atmospheric trace gases, understanding the drivers of trace gas cycling in surface waters and their release to the atmosphere is crucial for climate predictions. Furthermore, there is a serious lack of information related to trace gas cycling in the uppermost ocean, the Sea surface microlayer (SML). Production and consumption of trace gases was investigated in a five-week mesocosm study with North Sea water at the SURF facility (Wilhelmshaven, Germany), during which an extreme slick formed under a combined diatom and coccolith bloom. In addition to bulk sampling, the glass plate method was used successfully to sample trace gases in the SML. Findings are supported by an extensive set of parameters from other BASS subprojects.