Sediment simulation mathematical

Soil compartment chemical fate modeling has been traditionally performed for three distinct subcompartments the land surface (or watershed) the unsaturated soil (or soil) zone and the saturated (or groundwater) zone of a region. In general, the mathematical simulation is structured around two major cycles the hydrologic cycle and the pollutant cycle, each cycle being associated with a number of physicochemical processes. Watershed models account for a third cycle sedimentation. 

There are also several methods to determine patterns of fate and transport of pollutants in the environment. In some cases, microcosms and me-socosms are used to study fate, biodegradability, bioavailability, and transport within compartments. Field surveys may also be used to study fate and transport of pollutants in contaminated environments. Such studies involve collection and analysis of biota, water, air, soil, or sediment. In some cases, radioactively labeled contaminants ( tracers ) may be introduced in mesocosms or noncontaminated environments in order to determine their fate and patterns of transport. Finally, mathematical models are often used to produce computer simulations to... 

The characterization is based on the assumption that selected orientations for the major axes of magnetic resonance tensors exist. Another assumption is the random scattering of major axes with respect to this direction according to the Gauss law. The orientation and disordering parameters are optimised by simulation of theoretical ESR spectra and comparison with experimental spectra. The mathematical algorithm developed for the simulation program is also discussed. Results of this approach were applied to experimental data for films of copper phthalocyanine and dipivaloil methanate, obtained by sedimentation on quartz plates. 

Experimental and mathematical modeling studies were performed to evaluate the potential benefits and limitations associated with the use of nonionic surfactants to enhance the microbial transformation of hexachlorobenzene (HCB) by a dechlorinating mixed culture enriched from a contaminated sediment. In general. Tween series surfactants were shown to have little impact on methanogenesis, whereas, polyoxyethylene (POE) alcohols, Triton X-100 and SDS were found to strongly inhibit methanogenesis and HCB dechlorination. Subsequent experiments conducted with Tween 80 illustrated the ability of this surfactant to enhance the solubility of HCB and to reduce the HCB-soil distribution coefficient. Model simulations demonstrated, however, that the aqueous phase mass fraction of HCB was substantially reduced in micellar solutions, which corresponded with observed reductions in HCB dechlorination. These results indicate that the impacts of surfactants on both biological activity and contaminant phase distributions should be evaluated in order to accurately assess the potential for biotransformation of hydrophobic contaminants in the presence of surfactants. 

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