Abstract:

Soil carbon pool is an important component of total carbon pools in terrestrial ecosystems. Studying dynamical changes of soil carbon pool and its fractions are necessary to understand the effect of soil formation on CO₂ in the atmosphere. In this paper, the eastern Zhejiang marine plain with a single material source was selected, and the surface soil samples and profile layered soil samples were collected to study the effect of reclamation time on the soil carbon pool and composition of the marine plain. The results showed that enclosing of coastal tideland made soil separate from influence of sea water and improved plant growth, which increased accumulation of soil organic matter. Meanwhile inorganic carbon (CaCO₃) was gradually leached and moved downward from 1 m soil depth. As a consequence, contents of total organic carbon, particulate organic carbon, water-dissolved organic carbon, microbial biomass carbon and black carbon of the soils increased gradually with soil age, and inorganic carbon in the soils leached downward firstly, and finally disappeared from 1 m soil depth. Various fractions of organic carbon were found to be mainly accumulated in top layer of the soil profiles. It was also found that significant amount of dissolved organic carbon was moved downward and accumulated in deep soil. During soil development, organic carbon increased while inorganic carbon decreased, total carbon in the 1 m soil depth increased gradually in the first 86 year, and reached a relatively stable level, and then slightly decreased after 310 years of soil development.

Key words: coastal plain, organic carbon pool, inorganic carbon pool, long-term change, black carbon