The database consists of hourly atmospheric DMS concentrations, daily SO2 and total sulfate concentrations and three-day concentrations of size segregated aerosol sulfate. Samples were taken on the top of the navigation bridge of the CCGS Amundsen as it cruised along Baffin Bay and the Northwest Passage. Hourly samples of DMS was obtained using a customized DMS sampler. Samples were analyzed using a gas chromatograph fitted with a sulfur chemiluminesence detector (GC-SCD) to obtain atmospheric DMS concentrations. SO2 and total aerosol samples were obtained daily using a high volume sampler fitted with a quartz microfiber filter and K2CO3 treated cellulouse filter. Size segragated aerosol samples were obtained using a highvolume sampler fitted with slotted quartz filters on a 5 stage cascade impactor run for three days each sample. Concentrations of SO2, sulfate and MSA as well as other ions from the filter papers were obtained using ion chromatography. Delta34S values of SO2 and sulfate were obtained using a continuous flow isotope ratio mass spectrometer. Delta34S is reported based on the Vienna Canyon Diablo Troillite (V-CDT) international standard.

We are seeking answers to two key questions regarding the influence of marine processes on Arctic climate: 1) How will the increased flow of Pacific waters through the Canadian Archipelago affect the dynamics of climate-active gases in the ocean, and 2) How will these gases be affected by a reduction of sea-ice cover, and increased areas of open water? These questions have been addressed by our multidisciplinary team during two expeditions on the Canadian research ice-breaker Amundsen as part of the International Polar Year. The expeditions took place during the fall of 2007 and 2008. Eleven (2007) and ten (2008) Arctic SOLAS scientists from 7 Canadian institutions participated to these expeditions which allowed a unique and extensive longitudinal survey of these trace gases and aerosols in the High Canadian Arctic, from Baffin Bay to the Beaufort Sea. The missions enabled us to collect new oceanographic and atmospheric data on the distribution and cycling of DMS, N2O, and VOCs across the Canadian Archipelago and to relate these measurements to the distribution and chemical characteristics of aerosol particles. Activities of this program where coordinated with those of the IPY programs CFL, the Canadian program ArcticNet, and the international programs OASIS and SOLAS.

The database consists of hourly atmospheric DMS concentration, daily SO2 and total sulfate concentrations and three-day concentrations of size segregated aerosol sulfate. Samples were taken on the top of the navigation bridge of the CCGS Amundsen as it cruised along Baffin Bay and Lancaster Sound. Hourly samples of dimethyl sulfide was obtained using a customized DMS sampler. Samples were analyzed using a gas chromatograph fitted with a sulfur chemiluminesence detector (GC-SCD) to obtain atmospheric DMS concentrations. SO2 and total aerosol samples were obtained daily using a high volume sampler fitted with a quartz microfiber filter and K2CO3 treated cellulouse filter. Size segragated aerosol samples were obtained using a highvolume sampler fitted with slotted quartz filters on a 5 stage cascade impactor run for three days each sample. Concentrations of SO2, sulfate and MSA as well as other ions from the filter papers were obtained using ion chromatography. Delta34S values of SO2 and sulfate were obtained using a continuous flow isotope ratio mass spectrometer. Delta34S is reported based on the Vienna Canyon Diablo Troillite (V-CDT) international standard.

Real-time atmospheric measurements were made on board the CCGS Amundsen. Sampling lines were placed on the forward mast of the ship, and instruments were housed in a sampling shed located on the top deck. Mixing ratios of volatile organic compounds (VOCs: dimethylsulfide, acetone, methanol, benzene, etc.) were measured using proton-transfer-reaction mass spectrometry. Aerosol size distributions between 10 and 500 nm were measured using a scanning mobility particle sizer and total aerosol number concentrations > 3 nm were measured using an ultrafine condensation particle counter. All data have time resolution of minutes.

DMSP and DMS water concentrations were determine at fixed depths and at selected stations (ArcticNet stations) along a transect beginning in the North Water Polynya, going through the Lancaster Sound and the Northwest Passage, and terminating in the Beaufort Sea. During transit time, near surface DMS measurements were conducted every 2 hours from the pumping system of the CCGS Amundsen. In all cases, DMSP and DMS measurements were done following the methods of Kiene and Slezak 2006 (Limnol. Oceanogr.: Methods 4: 80-95). At selected stations, DMSP and DMS microbial cycling was determined during onboard incubations following the 35S-DMSP protocol (Merzouk et al. 2006, Deep Sea Res. 53:2370-2383).