%0 PDF %T Sediment Flux Modeling of Nutrients and Organic Pollutants %A WANG, Yuan. %8 2017-04-18 %R http://localhost/files/3x817037s %X Abstract: Excess nutrients and persistent organic pollutants (POPs) in water systems destroy ecosystem balance and prevent the beneficial use of water bodies. One important but often neglected and sometimes underestimated source is the internal loadings from the sediments. As such, accurate estimation of sediment-water flux is critically important to surface water quality modeling. In this thesis, the importance of the water side and sediment side controlling mechanisms on sediment-water flux was evaluated using a steady-state analytical model. It was found that diffusive boundary layer (DBL) poses big resistance to the transport of highly adsorptive chemicals such as PCBs. In view of the importance of DBL in controlling mass transfer, I zoomed in to study the impact of periodic flows (i.e., seiches and tides) on DBL and proposed a method using effective DBL thickness corresponding to the time averaged friction velocity to estimate the mean sediment-water fluxes of both organic pollutants and nutrients. In addition, a widely used Sediment Oxygen Demand (SOD) model was modified to incorporate the effect of DBL. The modified SOD model was capable describing the correlation between flow velocity and SOD seen in experimental datasets. Finally, a comprehensive diagenesis model named Huni2K (湖泥2K) was developed to numerically simulate nutrient fluxes. The software can produce steady-state and transient concentration profiles of 14 state variables in the sediments, including particulate organic matters (carbon, nitrogen and phosphorus) and dissolved constituents (oxygen, ammonium, nitrate, phosphate, and methane). The nutrient fluxes are calculated incorporating both sediment side kinetics and water side DBL effect. In addition, the flux of the methane gas can be obtained. The model can accurately simulate the inhibition of methane formation by overlying water sulfate concentration, which was a phenomenon poorly characterized in existing models.; Thesis (Ph.D.)--Tufts University, 2017.; Submitted to the Dept. of Civil Engineering.; Advisors: Steve Chapra, and Eric Adams.; Committee: Wayne Chudyk, and Andrew Ramsburg.; Keywords: Environmental engineering, and Water resources management. %[ 2022-10-11 %9 Text %~ Tufts Digital Library %W Institution