Around the globe, the coastal ocean is of immense importance, as it provides critical functions for the environment, society and economy. Sediments play a fundamental role in the wellbeing of coastal ecosystems as they are able to convert, store and release chemical compounds that affect and control life. Especially sandy sediments are likely highly efficient bioreactors and essential for coastal ecosystem functions and services; they potentially stimulate chemical reactions and the metabolic activity of biota and enhance fluxes of biologically important reactive solutes, such as oxygen and nutrients. However, due to the specific geophysical characteristics of these sandy coastal sediments, measurements that quantify the nutrient exchange between the sediments and the water column are difficult and the recycling capacity of nutrients in these sediments is not well quantified. In this project we propose to develop a new capacity to quantify the exchanges of nutrients between different types of sandy sediments and the water column.