# Panta Rhei

## Organic Carbon Decomposition Correlated with WRT

##### BY CHUNLIN SONG

Nature Geoscience have published an interesting paper entitled Organic carbon decomposition rates controlled by water retention time across inland waters. The main conclusion of this paper is that the decomposition rates of organic carbon in water are negatively correlated with water retention time (WRT). The half-life of organic carbon in inland waters (2.5 ± 4.7 yr) is shorter than terrestrial soils and marine ecosystems. This work is very inspiring, which would be helpful to my Ph.D. work.

The organic carbon in terrestrial soils was transported to oceans through rivers, which is an important component of global carbon cycle. However, the decomposition rates of organic carbon are largely unknown. The quantity of organic carbon mineralized and released to the atmosphere during its transport is unclear. That’s why we need to investigate the factors that control organic carbon decomposition rates.

Catalán et al. compiled 315 measurements of organic carbon decay rates, which include filed studies from the globle scale and bioassay studies. With ordinary least squares correlation analysis, they obtained the relationship between WRT and organic carbon decomposition rates:

$$logk = -4.5 (\pm 0.08) log WRT − 0.96 (\pm 0.03) (r^{2} = 0.41; p < 0.001; n = 315)$$

where k is the organic carbon decomposition rates (sensitive to the effect of temperature), WRT is the WRT (the ratio of the mass of a scalar in a water body to the rate of renewal of the scalar). This model indicates that the longer the WRT, the lower the organic carbon decomposition rates.

In addition, the authors calculated the concomitant changes in WRT of water body in a 2 degrees warmer world. The estimated future redistribution of the organic carbon decay rates shows a decrease in the Mediterranean biome (around −13%) and an increase in the boreal and tundra biomes (around 10%).

More information: Núria Catalán et al. Organic carbon decomposition rates controlled by water retention time across inland waters. Nature Geoscience 9, 501–504 (2016), doi:10.1038/ngeo2720.

categories: CARBON