DOI: 10.5281/zenodo.6523780
title: Measurements of benzene and toluene in underway surface seawater and ambient air in the Atlantic sector of the Southern Ocean on cruise ANDREXII/JR18005 between February and April 2019.

description: Benzene and toluene cycling iin the unpolluted marine environment s poorly understood. Due to a paucity of measurements, the role of the ocean in the atmospheric budgets of atmospheric benzene and toluene is unknown. In order to quantify the air-sea fluxes of these gases and obtain insights to their biogeochemical cycling, we measured their seawater concentrations (surface and depth profiles) and air mixing ratios in the Atlantic sector of the Southern Ocean, along a ~11000 km long transect at approximately 60o S in Feb-Apr 2019. The measurements were made using a Proton Transfer Reaction Mass Spectrometer coupled to a Segmented Flow Coil Equilibrator. Concentrations, oceanic saturations and calculated fluxes benzene and toluene are presented here. The data is further presented and discussed in a manuscript: Marine biogenic benzene and toluene emissions and their impact on secondary organic aerosol in the polar regions. Charel Wohl, Qinyi Li, Carlos A. Cuevas, Rafael P. Fernandez, Mingxi Yang, Alfonso Saiz-Lopez, Rafel Simó, Submitted to Atmospheric Atmospheric Chemistry and Physics, 2022 Computation of the air-sea gas fluxes is explained in detail in the linked manuscript about benzene and toluene. <br> Positive values indicate oceanic outgassing, thus sea to air flux. Definitions of acronyms, site abbreviations, or other project-specific designations:<br> deg = degree <br> SW = seawater concentration ATM= atmosphere SAT = saturation flux= air-sea flux in (micro)umol_m^(2)_d^(-1)<br> nM = nano Molar seawater concentration defined as nmol dm^(-3) LAT, LONG = Latitude, Longitude. (negative indicates west and south) The timestamp indicates sampling time in UTC, expressed as DD/MM/YYYY_HH:MM Empty data cells/points are listed as an impossible number of -999. Interruptions in the measurements are due to calibrations and other instrument maintenance.Interruptions in the calculated flux are due to missing auxiliary data at those sampling points e.g. no wind speed or underway auxiliary data. Fluxes and saturations computed using the interpolated air mixing ratio (see linked manuscript) are indicated with the suffix "_2" Negative values correspond to readings below the blank and detection limit. <br> They are effectively zero and are included here as the computed negative concentration to avoid skewing the mean. Data last modified 06.05.2022. Version 1 uploaded on that date. No further maintenance planned. This is the final data.
description: Sampling protocol: For underway seawater measurements, the SFCE nominally sampled from the bottom a glass bottle, overflowing with seawater from the underway seawater supply. The ambient air measurements were made using an air inlet installed in front of the bridge and using a 90m PTFE sampling line. Sampling is further described in the following reference: Wohl, C., Capelle, D., Jones, A., Sturges, W. T., Nightingale, P. D., Else, B. G. T., and Yang, M.: Segmented flow coil equilibrator coupled to a proton-transfer-reaction mass spectrometer for measurements of a broad range of volatile organic compounds in seawater, Ocean Sci., 15, 925–940, https://doi.org/10.5194/os-15-925-2019, 2019. The SUMMIT project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 834162). With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S).