Nutrient exchange fluxes in the dark and light, calculated in moles per hour per square metre, between sediment cores and overlying site water in salt marsh and intertidal mudflat locations in Essex and Morecombe Bay, Lancashire in January and August 2013. Net fluxes of nitrate, nitrate, ammonium, oxygen and dissolved organic carbon were measured in temperature controlled water baths over three hour periods. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. Full details about this dataset can be found at https://doi.org/10.5285/740348c5-796b-4a28-bc7f-b0eaf1ee3452
