BEGIN:VCALENDAR VERSION:2.0 PRODID:-//wp-events-plugin.com//6.4.4//EN TZID:Asia/Jerusalem X-WR-TIMEZONE:Asia/Jerusalem BEGIN:VEVENT UID:7@cee.technion.ac.il DTSTART;TZID=Asia/Jerusalem:20210812T123000 DTEND;TZID=Asia/Jerusalem:20210812T133000 DTSTAMP:20210715T072959Z URL:https://cee.technion.ac.il/en/seminars/nir-marom-a-method-for-estimati ng-biological-resuspension-fluxes-from-the-seabed/ SUMMARY:A method for estimating biological resuspension fluxes from the sea bed [No Categories] DESCRIPTION:Location: Civil and Environmental Engineering Speaker: Nir Mar om\n \n The talk will be given in Hebrew\n Abstract\n\nResuspension ofse diments in marine environments affects the exchange of water\, nutrients\, and organiccarbon between the seabed and the water column. Thus\, it has a strong influenceon the biology and geochemistry of the benthic ecosystem and the overlyingwater. Resuspension results from physical stresses impos ed by currents andwaves that form a nepheloid layer\, and from the benthic activity of organisms (hereafter“biological resuspension”) such as fi sh that borrow for food\, which typically generatesdistinct particle puffs . While physical resuspension is dominant in highcurrents and wavy coastal regions\, biological resuspension is the dominant mechanismin low-energy environments. While low-energy environments are predominant inthe deep sea they are also common in closed basins. Despite its importance\, lessthan a handful of estimates of the average fluxes that stem from biologicalresu spension are available. The main reason is the lack of methodologies thatc an quantify biological resuspension. In my research\, I have developed afo otprint model that estimates the vertical resuspension flux from measureme ntsof the horizontal advective flux. The footprint model is based on the i ntegralmass conservation law and considers advection and settling of the s edimentparticles. A rigorous derivation of the model was followed by a the oretical sensitivityanalysis that was performed to identify which environm ental parameters influencethe model accuracy. It was found that the grain size distribution\, the medianheight of the particles within the puff\, an d the puffs’ median height arecrucial to accurately estimate the resuspe nsion flux. To test the footprintmodel performance\, a Lagrangian stochast ic simulation program was developed.The program generates random puffs\, f ollows the particles locations as they areadvected and settle\, and measur es their concentration at simulated detectors. Usingthe simulated concentr ations\, the resuspension flux calculated by the footprintmodel was compar ed to the flux generated by the simulation. While the resultsshow high acc uracy for all the tested parameters\, we found that the model’sprecision is influenced by the number of puffs in each measurement\, thevariance of the vertical distribution of mass within the puff at the moment of resusp ension\,and by the variance of the puffs’ height. While the footprint mo del did not explicitlyaccount for the effect of turbulent dispersion\, I f ound that for the commonturbulence intensity value of 10% the results were still accurate (mean error<\;15%) for particles with settling velocity greater than 1.9 cm/sec. Thus\, itis concluded that the footprint model is highly accurate in areas of coarse sedimentor negligible turbulent disper sion.\n\n \; \n Link to Zoom invitation:https://technion.zoom.us/j/867 5790728 END:VEVENT BEGIN:VTIMEZONE TZID:Asia/Jerusalem X-LIC-LOCATION:Asia/Jerusalem BEGIN:DAYLIGHT DTSTART:20210326T030000 TZOFFSETFROM:+0200 TZOFFSETTO:+0300 TZNAME:IDT END:DAYLIGHT END:VTIMEZONE END:VCALENDAR