Simulated Effects of Atmospheric Deposition and Species Change on Nutrient Cycling in Loblolly Pine and Mixed Deciduous Forests

Johnson, Dale W.; Susfalk, R. B.; Swank, Wayne T.

doi:10.1007/978-1-4612-2178-4_27

Cited by 4 publications

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“…In the soil compartment, sorption and cation exchange are closely connected; see the paper of Johnson et al (1998), which is concerned with forest eco-systems for an example study. Cations as Ca 2+ , Na + , NH 4 + , Sr +2 , Al +3 exchange sorption places if the equilibrium is disturbed when water of different composition enters.…”

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Transport and Sorption

Holzbecher

2011

Environmental Modeling

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Aside from advection, diffusion and dispersion, which can be formulated separately for the solid and the fluid phases, the interaction between the phases is another process which is relevant in many environmental systems. Under certain conditions, particles in the pore space are attracted by the surface of the porous medium where some chemical processes tend to bind them in various ways. Different processes like electrical attraction and repulsion, complexation or chemical reaction can be distinguished in a detailed look, gathered under the general term sorption.In multiphase environments, sorption denotes processes that affect an exchange of components between phases. One can speak of interphase exchange. In porous media there is the exchange between solid and fluid phase, i.e. between the water in the pore space and the solid matrix. Adsorption denotes fluxes from the fluid to the solid phase, while desorption is the opposite process, in which there is a flux from the solid to the fluid phase. In the following the term mobilization is used frequently. A pollutant particle which has been fixed at the surface of the solid matrix in a first time period, may be re-mobilized and freed for dispersion and advection processes in a second time period.A schematic view on adsorption and desorption in the pore space of a porous medium is given in Fig. 6.1. In the remainder of this chapter, we will mostly refer to that multi-phase set-up as it is the standard concept for environmental models concerning groundwater, seepage water and pore water in aquatic sediments.In a first fundamental distinction, the speed of the processes governing interphase exchange in relation to the transport processes is of concern. One speaks of fast sorption if sorption is faster than the transport processes; and of slow sorption if sorption is slower than transport. Thus the characterization of sorption depends on the specific situation.Let c denote the fluid phase concentration and c s the solid phase concentration. Normally c and c s are not independent but connected. High or low concentrations in E. Holzbecher, Environmental Modeling,

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