Phosphorus exchange in eutrophied coastal brackish water sediments - sorption pattern, potential and factors affecting them

Phosphorus (P) exchange in clayey mud sediments was investigated with desorption-sorption isotherms at 22 coastal sites in the eutrophied brackish Gulf of Finland, the Baltic Sea. The aim was to gain information on P sorption potential and pattern of oxygenated surface sediments and to elucidate factors explaining them. Modified Freundlich equation was fitted to the isotherm data and used for calculation of the P exchange parameters EPC0 (equilibrium P concentration at zero net sorption), k(E)(PC0), k(15) and k(100) (P buffering capacities at early, middle and high sorption stages, respectively). They were further used to assess the P sorption potential and pattern of the sediments. Sediment properties explaining the P sorption potential at different sorption stages were identified.The greatest sorption potentials were recorded in originally poorly oxic sediments in the inner archipelago with accumulated fine particulate material, high in adsorbents for P, transported from the watersheds. After oxygenation, they were high in amorphous Fe-oxyhydroxides, which explained their efficient P sorption (k(EPC0) > 1.32 I g(-1)). Poorer P sorption (k(EPC0) 0.45-0.84 I g(-1)) was recorded in fine sediments abundant in Al-oxyhydroxides, presumably due to their higher original P occupation degree. The lowest sorption potentials were found in the outer archipelago sediments. Their lowest specific surface areas and highest original P contents referred to scarcity of adsorbents and high occupation degree of the existing ones. These results suggest that the coastal clayey mud sediments investigated possess high P sorption potential, which can be markedly diminished by eutrophication-induced hypoxia but recovered if oxygen conditions improve.peerReviewe

Discovering Europe's seabed geology: the EMODnet concept of uniform collection and harmonization of marine data

Maritime spatial planning, management of marine resources, environmental assessments and forecasting all require good seabed maps. Similarly there is a need to support the objectives to achieve Good Environmental Status in Europe's seas by 2020, set up by the European Commission's Marine Strategy Framework Directive. Hence the European Commission established the European Marine Observation and Data Network (EMODnet) programme in 2009, which is now in its fourth phase (2019–21). The programme is designed to assemble existing, but fragmented and partly inaccessible, marine data and to create contiguous and publicly available information layers which are interoperable and free of restrictions on use, and which encompass whole marine basins. The EMODnet Geology project is delivering integrated geological map products that include seabed substrates, sedimentation rates, seafloor geology, Quaternary geology, geomorphology, coastal behaviour, geological events such as submarine landslides and earthquakes, and marine mineral occurrences. Additionally, as a new product during the ongoing and preceding phase of the project, map products on submerged landscapes of the European continental shelf have been compiled at various time frames. All new map products have a resolution of 1:100 000, although finer resolution is presented where the underlying data permit. A multi-scale approach is adopted whenever possible. Numerous national seabed mapping programmes worldwide have demonstrated the necessity for proper knowledge of the seafloor. Acting on this, the European Commission established the European Marine Observation and Data Network (EMODnet) programme in 2009. The national geological survey organizations of Europe have a strong network of marine geological teams through the Marine Geology Expert Group of the association of European geological surveys (Eurogeosurveys). This network was the foundation of the EMODnet Geology consortium which today consists of the national geological surveys of Finland, the UK, Sweden, Norway, Denmark, Estonia, Latvia, Lithuania, Poland, The Netherlands, Belgium, France, Ireland, Spain, Italy, Slovenia, Croatia, Albania, Greece, Cyprus, Malta, Russia, Germany, Montenegro and Iceland, as well as marine teams of research organizations in Portugal (IPMA), Bulgaria (IO-BAS), Romania (GeoEcoMar), the UK (CEFAS), Greece (HCMR) and Ukraine (PSRGE, replaced in the fourth phase by Institute of Geological Sciences, NAS of Ukraine). The consortium is further strengthened with experts from six universities: Edge Hill University (UK), Sapienza University of Rome (Italy), University of Tartu (Estonia), University of Crete through FORTH-ICS, Institute of Marine Science and Technology of Dokuz Eylul University (Turkey), and EMCOL Research Centre of Istanbul Technical University – altogether, 30 partners and nine subcontractors. The EMODnet Geology programme is now in its fourth phase, which started in September 2019. In addition to geological information, the wider EMODnet programme aims to also bring together information from European seas on seabed habitats, physical properties, chemistry, biology, human activities and hydrography. This paper describes the EMODnet Geology project and the different end products which were delivered in the end of the third phase and will be further developed during the recent fourth phase of the project