HEADLINE 50 OCEAN & COASTAL WATERS BONUS research expedition team members. Photos: Dr. Martin Hassellöv SonTek CastAway CTD deployed via a fishing rod at regular intervals. Check out more information on the Hrimfare af Ranrike at hrimfare.com Charting a Course A significant portion of SHEBA focuses on gaining a better understanding of pollution. Last year, a 20m (67ft) long, former long distance race yacht was converted into a mobile science lab on water and has served in the SHEBA project to sample for water and air quality conditions in heavily travelled ship lanes. Using the Hrimfare af Ranrike, a sailing vessel with no engine emissions, removed the potential problem of self- contamination and possible impacts on the accuracy of the measurements. During the 2016 summer expedition, the boat was packed with equipment to measure and collect samples in the atmosphere and in the water as it roamed the Baltic Sea, crossing ship lanes perpendicularly. A cluster of surface skimming sensors were attached to a stainless steel pole and mounted about 1m below the surface in the stern of the boat such that measurements were undisturbed by the boat itself as it advanced. The sensors collected data on dissolved oxygen, salinity, temperature, pH, pCO2 (carbon dioxide partial pressure; the partial pressure of carbon dioxide, a measure of the relative concentration of the gas in air or in a fluid) and oil. A SmartGuard sensor hub was placed in the forward sail locker to record data from the sensors and the ship’s GPS every 20 seconds. As the Hrimfare crossed ship lanes, changes in most of the measured parameters could be clearly detected. Differences in the surface water inside and outside the shipping areas lanes could be attributed to the mixing of the upper ocean by the large vessels. These ships also expel engine cooling and scrubber water, as well as wastewater from the crew living onboard, which affect the water quality of the sea. To gain a better understanding of the mixing occurring in deeper layers, caused by the ships traffic, Hrimfare stopped at regular intervals to deploy a SonTek CastAway CTD. This hand-operated device has built-in GPS for geospatial mapping of salinity, temperature and depth measurements. Each stop included two to three consecutive profiles and took less than five minutes. Two self-recording acoustic profiling instruments were also dropped below the ship lanes to measure currents in thin layers from the bottom to the surface. The instruments also measure salinity, temperature, dissolved oxygen and suspended particles (turbidity) and are typically deployed for 6-12 months, recording data at least every hour. Continuous air measurements were done by mounting a sampling tube in the mast through which air was pumped into a set of instruments installed below the deck. The measured parameters included CO2 , NOx , SO2 , size-resolved particulate matter (PM) and soot (black carbon). Initial analysis of the data showed that signatures of exhaust plumes from individual ships could be identified for the measured gases and particles. For example, when passing a scrubber- equipped ship, clear signals for NOx , CO2 and PM could be detected. The air pollution from nearby land regions could also be detected. These measurements are similar to those done in urban areas when studying air pollution from traffic and industry.