Atmosphere-Ocean-Islands-Biogeochemical interactions in the Macaronesian Archipelagos of Cabo Verde, the Canaries and Madeira POS533: 28. February 2019- 22. March 2019 Mindelo (Cabo Verdes) – Las Palmas (Spain) AIMAC

• Main Author: Quack, Birgit
• Format: Report
• Language: English
• Published: GEOMAR 2019
• Subjects: Las Palmas; North East Atlantic; Ocean Island
• Online Access: https://oceanrep.geomar.de/id/eprint/48193/; https://oceanrep.geomar.de/id/eprint/48193/1/cr_pos533.pdf; https://doi.org/10.2312/cr_pos533

Poseidon 533 – AIMAC (Atmosphere–ocean–island-biogeochemical interactions in the Macaronesian Archipelagos) investigated the influence of the Cape Verdes, the Canary Islands, and Madeira on the physics, chemistry and biology of the surrounding subtropical North- East Atlantic ocean. The air – sea exchange of halocarbons from marine sources impact tropospheric and stratospheric chemistry, and therewith air quality and human health. High oceanic and atmospheric concentrations of iodinated, brominated and chlorinated methanes are often found near coastlines. In particular, bromoform (CHBr3) was recently detected at unexpectedly high concentrations in seawater of subtropical coasts, e.g. at Miami and Tenerife beaches. Bromoform is produced naturally from macro algae and phytoplankton and is the major marine vector of organic bromine to the atmosphere. Together with dibromomethane (CH2Br2), it is the main contributor to natural stratospheric bromine, involved in ozone depletion. Bromoform is also a major product during disinfection of seawater for many industrial and recreational purposes and during desalination processes. While the bromoform production from phytoplankton generally leads to picomolar concentrations in seawater, macroalgal production yields nanomolar concentrations and disinfection processes involving seawater can increase concentrations to micromolar levels. The latter has led to the occasional application of this compound as tracer for the effluents of power plants and wastewater discharges. Other disinfection by-products (DBP) in the effluents can lead to unfavorable effects on the environment and human health. As bromoform shows large concentrations in urbanized and industrialized regions, the elevated concentrations at many coasts may have a major and increasing contribution to the global budget. We hypothesize, that populated coastlines show elevated bromoform concentrations from disinfection activities, related to the amount of population and industrial activities. Coastal alongshore currents ...