1st International Congress on Environmental Modelling and Software - Lugano, Switzerland - June 2002
Keywords
weathering, carbon sink
Start Date
1-7-2002 12:00 AM
Abstract
In the framework of "active planetary cover" concept the influence of weathering on the atmosphere carbon and, as a consequence, on the climate is considered. The relatively slow process of chemical weathering, which is accompanied by an uptake of carbon from the atmosphere and its transportation to the intercontinental and epicontinental seas, is significantly amplified by terrestrial ecosystems. The mechanism of amplification is explained by an increase in CO2 concentration in the "soil" atmosphere caused by root respiration and the metabolism of micro-organisms, the so-called "respiration of soil". In accordance with Zavarzin’s estimation, the concentration of CO2 in the soil air is 60-80 times larger than in the atmosphere. All this leads to a significant acceleration of weathering in soil. It seems that such a concentration gradient cannot be maintained and it will be eroded by diffusion. It is true if we consider bare soil. But in real ecosystems the litter covers soils, so that molecular diffusion becomes prevalent. In other words, the litter can be considered as a semi-permeable membrane for CO2. The second stage is to describe the chemical transformations of carbon within the system. However here we deal with an open system, and therefore we were compelled to develop some partial case of the theory of chemical equilibrium in open systems.
Weathering in Terrestrial Ecosystems: Carbon Sink
In the framework of "active planetary cover" concept the influence of weathering on the atmosphere carbon and, as a consequence, on the climate is considered. The relatively slow process of chemical weathering, which is accompanied by an uptake of carbon from the atmosphere and its transportation to the intercontinental and epicontinental seas, is significantly amplified by terrestrial ecosystems. The mechanism of amplification is explained by an increase in CO2 concentration in the "soil" atmosphere caused by root respiration and the metabolism of micro-organisms, the so-called "respiration of soil". In accordance with Zavarzin’s estimation, the concentration of CO2 in the soil air is 60-80 times larger than in the atmosphere. All this leads to a significant acceleration of weathering in soil. It seems that such a concentration gradient cannot be maintained and it will be eroded by diffusion. It is true if we consider bare soil. But in real ecosystems the litter covers soils, so that molecular diffusion becomes prevalent. In other words, the litter can be considered as a semi-permeable membrane for CO2. The second stage is to describe the chemical transformations of carbon within the system. However here we deal with an open system, and therefore we were compelled to develop some partial case of the theory of chemical equilibrium in open systems.
