The use of 7Be to identify event and seasonal sedimentation near the Po River delta, Adriatic Sea

Short-term dynamics of sedimentary organic matter in a littoral area of the North Adriatic Sea (Italy): Evidence from234Th and7Be

“…Particle reactive radiotracers such as 234 Th and 7 Be have been extensively used to help distinguish the varying sedimentary processes affecting coastal systems [1]. These radiotracers have been used in a number of applications including measuring sediment flux, resuspension events, event and seasonal deposition and sediment mixing [2][3][4][5][6]. Detectable 7 Be at dept is indicative of recently discharged fluvial sediment on the seabed, whereas detectable 234 Th indicates rapid deposition of any type of suspended sediment (i.e.…”

Sediments in the Tema Harbour (Ghana): chemical pollution and sedimentation rates

“…234 Th is produced from the decay of 238 U (half-life = 4.5 x 10 9 y), while 7 Be is a cosmogenic radionuclide produced from the interaction of cosmic rays with oxygen and nitrogen in the stratosphere and the troposphere (Sharma et al, 1987;Pfitzner et al, 2004;Palinkas et al, 2005). In marine environments,…”

“…Therefore, the activity profiles of 7 Be, 234 Th exc and 210 Pb exc were related to the mass-depth (mass of sediment per unit area, g.cm -2 ) instead of the linear-depth of the sediment . Inventories of 7 Be were determined for each core by integrating their downcore activities Mullenbach et al, 2004;Palinkas et al, 2005). The simplest SAR modelling approach, defined by the assumptions of constant flux and constant sedimentation rate (CF-CS) without any post-depositional redistribution , was applied to the sediment cores to derive very recent (3-8 months) SARs based on the measured 7 Be activity profiles.…”

“…For example, atmospheric 210 Pb and 137 Cs may first deposit onto soils and subsequently transported into aquatic systems (Abril and Garcia-Le6n, 1994;Mabit et al, 2014), in which case the flux of matter into the aquatic system will exert a greater control on the 210 Pb exc flux onto the bottom sediments than direct atmospheric 210 Pb exc deposition (Abril and Brunskill, 2014). Since the fluxes of matter is affected by storm runoff, floods and tidal events (Palinkas et al, 2005;Díaz-Asencio et al, 2009), which may be siteand time-specific, the application of a particular model at different sites would require a case by case assessment of sediment cores Abril and Brunskill, 2014). Moreover, the assumption of no post-depositional mobility of sediment-bound tracers under the application of 210 Pb dating models may also not hold in reality due to potential diffusion and advection of the tracers within the sediment pore water (Appleby and GarciaLe6n, 1997) under the influence of the sediment porosity ).…”

“…When 238 U decays to 234 Th, this high particle-reactive isotope is taken up by Suspended Particulate Matter (SPM) and surface sediments, where it can be found in excess with respect to the background levels, referred to as excess 234 Th ( 234 Th exc ). 7 Be and 234 Th exc profiles, when combined with 210 Pb and 137 Cs profiles in sediment cores, are useful for understanding sediment dynamics in aquatic systems (Sharma et al, 1987;Fuller et al, 1999;Palinkas et al, 2005;. In addition to radionuclide profiles in sediment cores, sediment traps are important tools for investigating short-term fluxes and dynamics of sediments in aquatic systems .…”