Measurements of Methanethiol (MeSH) and dimethyl sulfide (DMS) in surface seawater during 2022 at the monthly sampling observatory of Blanes Bay Microbial Observatory.

Global emissions of methanethiol are highly uncertain and the drivers influencing its seawater concentrations are quasi unexplored. Here we try to address this gap in our understanding by contributing new seasonally resolved seawater measurements. Mediterranean surface seawater sampling at the Blanes Bay Microbial Observatory was carried out monthly during 2022. January, March and April were not sampled due to technical difficulties. Seawater was hand-collected in glass sampling bottles around 11:00 am each day. The samples were kept in the dark and analysed at the ICM-CSIC for MeSH and DMS with the Vocus-PTR coupled to SFCE within 3 h of sample collection. This dataset contains MeSH and DMS surface seawater concentrations and relevant auxiliary data (chlorophyll a, sea surface temperature and sea surface salinity). Sea surface temperature and salinity were determined using a CTD profiler Model SD204 (SAIV A/S). The chlorophyll from the Blanes 2022 timeseries was measured on a fluorometer (10AU Turner fluorometer).

Details on the measurement methodology can be found here:

Wohl, C.; Güell-Bujons, Q.; Castillo, Y.M.; Calbet, A.; Simó, R. Volatile Organic Compounds Released by Oxyrrhis marina Grazing on Isochrysis galbana. Oceans 2023, 4, 151-169. https://doi.org/10.3390/oceans4020011

Definitions of acronyms, site abbreviations, or other project-specific designations:

Lat=latitude (negative indicates south)

Lon=longitude (negative indicates west )

Hourlybin = The mean measured concentration during each hour is shown, 30 min either side of the listed time. The timestamp indicates sampling time in UTC, expressed as  DD/MM/YYYY HH:MM

MeSH_nM= methanethiol surface seawater concentration in nM, defined as nmol dm^(-3)

DMS_nM= dimethyl sulfide surface seawater concentration in nM, defined as nmol dm^(-3)

fluo = chlorophyll a concentration in mg m^(-3)

SST= sea surface temperature in degrees Celsius

SSS= sea surface salinity in practical salinity units (PSU)