This cruise is part of the UK science contribution to the international SOLAS project (Surface Ocean Lower Atmosphere Study www.uea.ac.uk/env/solas/) which aims to advance our understanding of environmentally important interactions between the ocean and the atmosphere. Data collected during the cruise will help to determine the influence of coastal/shelf regions (20-200 km offshore) on microbiological activity in the ocean and chemical interactions between the ocean and the atmosphere. Deep water containing high concentrations of nutrients such as nitrate, and gases such as nitrous oxide and methane, rises to the surface (upwells) at the Mauritanian shelf edge and moves offshore. These nutrients can be chemically altered by sunlight and used by bacteria and microscopic plants to grow. The gases escape to the atmosphere and contribute to global warming. This cruise will sample the upwelled water as it moves offshore measuring its temperature, salinity, nutrient and gas content and the impact this water has on microbiological growth and atmospheric composition in order to improve international global climate models. The cruise has three scientific objectives: 1. To determine the role of upwelling on the supply, loss and air-sea exchange of climatically important gases produced by plankton 2. To determine the role of light in breaking down upwelled and recently produced dissolved organic matter and in producing climatically important trace gases 3. To determine the impact of nutrient enriched upwelled water on the spatial and temporal variability of plankton community structure and activity and resultant influence on biogenic gas flux
The aims of this cruise were to elucidate the processes responsible for controlling iodocarbon concentrations and provide a dataset that can be used to develop modelled estimates of iodocarbon sea-air fluxes in tropical Atlantic waters.