Co-effect of phosphorus and cadmium interaction on fraction distribution and accumulation of phosphorus in mangrove-sediment system

ABSTRACT

Mangrove [Kandelia obovata (S. L.)] seedlings were cultivated in rhizoboxes under different rates of phosphorus (P) and cadmium (Cd) level. The speciation distributions of P both in the rhizosphere and non-rhizosphere sediments were examined using sequential extraction procedures. P contents in different K. obovata (S.L.) tissues were also determined. Results showed that considerable differences existed in P speciation distribution between rhizosphere and bulk sediments. A higher proportion of iron-bound phosphate (Fe-P) was found in the rhizosphere sediments, while a relatively higher concentration of exchangeable phosphate (Ex-P) and Aluminum-bound phosphate was found in the bulk sediments. P accumulation in plant tissues was significantly positively correlated to Ex-P and Fe-P. Results indicated that root activities play an important role in the P cycling. And the coexistence of P and Cd induced higher P accumulation in mangrove plants. It is suggested that the root-induced chemical and biological changes in the rhizosphere environment play an important role in enhancing the bioavailability of soil P.

KEYWORDS:

• phosphorus
• speciation
• mangrove
• rhizosphere

Acknowledgment

The authors would like to thank Prof. John Merefield for his assistance with English grammar.

Funding

This work was jointly supported by the Guizhou Province Scientific Research Program numbered [2016]1102 and the Guizhou Normal University Scientific Research Foundation.