Carbon travel, destination: Soil

The general flow of the carbon to be transferred from the air to the soil is illustrated bellow:

The photosynthesis is a vital procedure for the plants that ensures a carbon sequestration in the terrestrial and aquatic environment up to 60 Pg-C for both (Cramer et al. 2001).

The plants capture CO₂ from the atmosphere using the mechanism of photosynthesis. This procedure secures the food supply for the plant and reduces the carbon dioxide as we saw in the previous post.

Photosynthesis 

Following the life cycle of the plants, the dead plant material in the soil gives organic matter that stats to decompose. This biological process is affected by (Bot & Benites, 2005):

1. Soil organisms,
2. The physical environment, and
3. The quality of the organic matter

The decomposition of the organic matter is a biochemical process that soil organisms use to produce food by converting the plant residues into humus (giving a black colour in the soil as illustrated below) with the process called humification. That releases useful nutrients in a form that the plants can absorb back. Other product of the decomposition is the carbon dioxide that goes back to the atmosphere(Bot & Benites, 2005).

Soil rich in humus (left) and no humus rich soil (right)

The following figure illustrate the carbon cycle in the soil:

Soil Carbon Cycle

The humus produced by the metabolism of the soil organisms is the most common carbon compound in the terrestrial ecosystem and it is very stable as it cannot be used further by the micro-organisms (Bot & Benites, 2005). 

Thus, the carbon starts to be sequestrated in the soil, reducing the CO₂ concentration in the atmosphere. 

Next in our trip we will examine where the carbon in the soil is and what it is doing there!

See you!

An unknown 'fight'

Hi everyone! Today I will show you a natural continuous conflict that all people depend on:

The whole system of the carbon cycle “fights back” the anthropogenic CO₂ (one important greenhouse effect) using the fluxes illustrated in the 2nd post.

• The oceans:

The oceans uptake large amount of CO₂ derived from the difference between the carbon concentrations in the atmosphere and the surface of the oceans. The limitation of this absorption is that the increase of the CO₂ emissions in the air reduces the uptake from the oceans because of the:

1.   Reduction of the buffer capacity of the oceans

1.   Mixing rate between the surface and the deep water

The result of the carbon dissolved in the sea is the lower pH that effect the marine life (Prentice et al., 2003).

• The terrestrial system:

The terrestrial system absorbs the CO₂ from the atmosphere with the help of the vegetation. The carbon sinks in the terrace is connected with the photosynthesis. More carbon dioxide in the atmosphere means more production by the plants. On the other hand, high concentration of atmospheric CO₂, does not benefit the production at the same scale. Thus, the ability of the terrestrial ecosystem to sink carbon from the atmosphere is limited. (Prentice et al., 2003)

The following video illustrates the human impact in the carbon fluxes and the result of the increasing CO₂ in the atmosphere (greenhouse effect).

 human impact in thecarbon fluxes

Next time we will continue our trip in Carbonland examining the terrestrial mechanisms.

See you!