Sink function

This means that the observed change in M mainly reflects a change in the source flux Q or the sink function. As an example we may take the methane concentration in the atmosphere, which in recent years has been increasing by about 0.5% per year. The turnover time is estimated to be about 10 years, i.e., much less than Tobs (200 years). Consequently, the observed rate of increase in atmospheric methane is a direct consequence of a similar rate of increase of emissions into the atmosphere. (In fact, this is not quite true. A fraction of the observed increase is probably due to a decrease in sink strength caused by a decrease in the concentration of hydroxyl radicals responsible for the decomposition of methane in the atmosphere.)... 

The complex interactions amongst geological, biological, and geochemical processes at the land-sea margin control the delivery and fate of radionuclides, contaminants, and other natural elements in coastal environments (Swarzenski et al. 2003). For many such constituents, there is at least a fundamental understanding of major source and sink functions and their potential estuarine transformation reactions. For example, rivers can be monitored quite easily for discharge rates into estuaries as well as for elemental... 

Friedel, J.K., Gabel, D. and Stahr, K. 2001. Nitrogen pools and turnover in arable soils under different durations of organic farming II Source-and-sink function of the soil microbial biomass or competition with growing plants Journal of Plant Nutrition and Soil Science-Zeitschriftfur Pflanzenernahrung und Bodenkunde 164 421-429. 

An interesting extension of this example is to consider two stationary sinks located at rt and r2, each with a sink function given by the Heaviside expressions... 

On the other hand the environment receives the wastes or pollutants from production processes. It is put under stress by utilization and consumption of resources as well as the destruction of the products. Overloading of the supply and sink function of the environment influences its control function, i.e. the preservation of the ecological equilibrium is threatened. This is shown in Figure 1 [1], [2]. 

VIII Survey of Ts/LU parameters Contiguity, source/sink, functional role, disturbance incorporation, geophys. instability, fauna interest, transformation, etc ... 

When the solvent dynamics are faster than those of ET, the population on the donor state has enough time to maintain the thermal distribution during ET. Thus, TST can be used to calculate the ET rate. This rate can be also used as the sink function to describe the fast vibrational modes in the treatment of solvent-controlled ET reactions. 

For organic molecules in solution, both the molecular vibrational motions and the solvent relaxation play important roles in ET. Usually, the vibrational motions are much faster than the solvent polarization motion because the vibrational motions have much higher frequencies. Thus, the thermal equilibrium may be maintained for those vibrational modes during the course of ET. In this case, one may separately consider the intramolecular vibrational motions and solvent motions. Along the directions of the high-frequency modes, ET can still be described by NA-TST, but the solvent motion has to be treated with the dynamic equations. Sumi and Marcus proposed a method to describe such a kind of ET, where the solvent motion satisfies the dififusion reaction equation and intramolecular ET is incorporated with a sink function in the diffusion equation. In the original SM theory, the sink function is obtained from the... 

Here k x) is the sink function that invokes the contribution from the fast modes. The generalized Smoluchowski operator L,- is given by ... 

Note that the sink function represents the local reaction rate along the intramolecular vibrational coordinate g at a given solvent coordinate x. It can be obtained from eqn (12.4) or eqn (12.19) together with the ZN formula or R-matrix approach for wide electronic coupling strengths. 

ET rate as a function of the relaxation time Tj with T = 300 K and 7/ 5 = 800 cm . Solid line, dashed line and dotted line correspond to Ifa, 1/t and long time rates, respectively, obtained from the R-matrix theory as the sink function. Filled circles with dotted line, filled triangles with dotted line and filled squares with dotted line are those obtained from the local FGR as the sink function. 

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