This research aims to analyse the sediment capacity to buffer free sulphide release in three coastal lagoons which differ in terms of eutrophication level, tide influence and primary producer communities . A preliminary estimate of soluble reactive phosphorus (SRP) regeneration coupled with sulphide fluxes is also made . Sediment profiles of ferrous and ferric iron and reduced sulphur pools were determined in three stations in the Bassin d'Arcachon (South West France), in one site in the Etang du Provost lagoon (Southern France), and in three stations in the Sacca di Goro lagoon (Northern Italy) . Laboratory experiments were also conducted by incubating sediment slurries . Slurries from the French lagoons were also enriched with about 2% d .w. of organic detritus obtained from the dominant macrophytes of each site, namely Zostera noltii and Ruppia cirrhosa (Bassin d'Arcachon), and Ulva rigida (Etang du Provost) . In the Sacca di Goro, slurry experiments were conducted at two sites with different salinity range, sediment composition and hydrodynamics .Field data showed that concentrations of available iron (Fe(II)+Fe(III)) ranged from a minimum of 28 .5 pmol cm -3 (Etang du Provost) to a maximum of 275 .7 µcool cm -3 (Sacca di Goro) . Moreover, in the French lagoons, acid volatile sulphide (AVS) accumulation in the superficial sediment was related to ferrous iron concentrations . Laboratory experiments showed that in spite of strong reducing conditions, sulphide and SRP release was weaker in iron-rich sediments and in those enriched with the most refractory organic matter . The highest fluxes were detected in sediment slurries from the Etang du Provost, which had the lowest iron content, supplied by 2% of the labile detritus from Ulva rigida. In this case, SRP release was directly related to sulphide production .Two factors seem significant to evaluate the buffer capacity against free sulphide and SRP release from anoxic sediment : organic matter biodegradability, which forces sediment toward reducing conditions, and iron availability, which can affect sulphide mobility as well as the ironhydroxide-phosphate-sulphide system .

No abstract

During 1994 net sediment-water fluxes of oxygen, ammonium and inorganic phosphorus as well as sediment profiles of organic matter, nitrogen, phosphorus and iron were determined in three shallow eutrophic environments . Investigations were conducted monthly from March to December at five stations in the Sacca di Goro (Po River Delta, Italy). In the late summer, samples were collected from a single site in the Prevost lagoon (French Mediterranean coast) and three stations in the Bassin d'Arcachon (French Atlantic coast) . In the Sacca di Goro, water-sediment exchanges of 02, NH4 and p03-were estimated by means of core incubation in the dark . Benthic fluxes for the French lagoons were in part determined experimentally using benthic chambers and in part from the literature .In general in the Sacca di Goro the highest oxygen uptake and nutrient release rates were found at the central sites, affected by macroalgal growth . At the sampling site adjacent to the freshwater inlet, sediment-water exchanges were principally influenced by tidal activity. In terms of organic matter and nutrient levels, sediments from the Sacca di Goro and from the Prevost lagoon, both colonised by the floating macroalga Ulva rigida C . Agardh, were similar. Sediments from the inner sheltered site in the Bassin d'Arcachon, invaded by the rooted macrophyte Ruppia cirrhosa (Pet .) Grande, showed the highest total N and P content (363 ± 157 pmol N cm -3 and 15 ± 2 pmol P cm -3as average values in the top 10 cm of sediment), but were low in pore water ammonium and orthophosphate probably due to the high sequestering capacity of the system and/or efficient coupling between bacterial nutrient regeneration and assimilation by the plant roots . In addition the outer tidal stations in the Bassin d'Arcachon, invaded by rooted macrophytes, were low in pore water nutrients . A different trend was evident in the Prevost lagoon where the concentrations of exchangeable inorganic phosphorus and ammonium were appreciable (0 .28 ± 0 .07,umol P cm -3 and 2 .4 ± 1 .4 tmol N cm -3 as average values in the top 10 cm of sediment) . High amounts of dissolved organic nitrogen were found in the pore water at all the sites investigated showing the key role of the organic nitrogen in the recycling of nitrogen in these systems . The hypothesis that iron is a key factor in controlling phosphorus release is discussed since the Sacca di Goro, which is subject to dystrophic crises, is richer in iron than the Bassin d'Arcachon, which is a more buffered system .

No abstract

The 4th International Polar Year featured a range of large international research projects and included a focus on Education and Public Outreach (EPO). ANDRILL (the ANtarctic geological DRILLing Project) was a large international (USA, New Zealand, Italy, Germany) multidisciplinary research project investigating the sedimentary record of Cenozoic ice sheet dynamics that brought approximately 160 scientists to McMurdo Station in the 2006 and 2007 field seasons, during which two > 1000 m sediment cores were successfully retrieved from the floor of the Ross Sea. ARISE (ANDRILL Research Immersion for Science Educators), the EPO arm of ANDRILL, deployed an international team of six to eight educators each season to Antarctica and embedded them with science teams. ARISE was unique in the EPO spectrum because it deployed a team of international educators together with an EPO coordinator, offered an on-ice geoscience course for the educators, and supported educator participation at both pre-ice and post-ice meetings. Conservative estimates indicate that at least 314,700 individuals have been reached directly through the wide range of ARISE EPO endeavours.Educator field research immersion is a small subset of educator professional development (PD) opportunities, with little quantitative or qualitative evaluation of polar immersion experiences having been reported. Here, surveys of ARISE educators and scientists are used to evaluate the efficacy of the ARISE program as PD in the context of research on educator PD. Persistent and recurring themes emerging from the surveys are: (1) the positive and reinforcing impact of deployment as a team; (2) the importance of access to scientists across an extended period of time and venues; (3) the importance of ‘doing science’ as a means of learning; and (4) recognition of the senses of excitement, engagement and inspiration displayed by both educators and scientists − about drilling progress, core interpretation, and outreach plans – and the EPO audience. Key components of the program are shown to be (1) deployment of a multi-educator team; and (2) guidance and support of the EPO coordinator at all phases of the ARISE experience.