湿地生态系统磷迁移转化机制研究进展

磷在湿地生态系统中的生物地球化学行为备受关注。湿地土壤以有机磷(OP)为主,无机磷(IP)为辅。铁铝结合态磷(Fe/Al-P)是IP的主要组分,钙镁结合态磷(Ca/Mg-P)惰性最强。OP因与土壤成分固定程度较低,更易在土壤中移动,而成为优于总磷(TP)可指示水体富营养化程度的指标。土壤酸碱度、温度、有机质含量、干湿交替和C∶N∶P是影响湿地生态系统磷生物地球化学循环过程的关键环境因素。耕地恢复为湿地后,湿地土壤TP含量基本呈升高趋势。速效磷(A-P)因对土壤理化性质的改变比较敏感,不同区域研究结果差异较大。随着退耕年限的延长,湿地土壤对磷的最大吸附量(Xm)、最大缓冲容量(MBC)和吸附常数(K)逐渐升高;但退耕初期,湿地土壤对磷的解吸率较高,可能会造成周边水域水体富营养化。

Research Progress on Phosphorus Migration and Transformation in Wetland Ecosystem

The ongoing process of exogenous resource purification and endogenous resource release during wetland restoration brings potential risk to surrounding water bodies. Investigating the biogeochemical behavior of phosphorus in wetland ecosystems is important for understanding the transformation of exogenous and endogenous resources as they are purified and released during ecological restoration of wetlands, and has received considerable attention. In this review, we summarize research advances on phosphorus biogeochemistry in wetland ecosystems. Organic phosphorus (OP) is the primary component of total phosphorus (TP) in wetland soil, supplemented with inorganic phosphorus (IP). Iron-aluminum bound phosphorus (Fe/Al-P) is the main component of IP, followed by calcium-magnesium bound phosphorus (Ca/Mg-P), a more stable component. OP is better than TP for indicating the degree of eutrophication in water bodies near a wetland being restored because it is less fixed to wetland soil and more mobile. The key environmental factors affecting phosphorus biogeochemistry in a wetland ecosystem are pH, temperature, soil organic matter (SOM), alternating dry and wet conditions, and the elemental ratio of C:N:P. After restoring farmland to wetland, the resulting TP content in the wetland soil tends to increase and available phosphorus (A-P) varies spatially due to the difference in soil physicochemical properties. When a wetland is restored, the maximum phosphorus uptake (Xm), maximum buffer capacity (MBC) and adsorption constant (K) of the wetland soil gradually increases. However, at the initial stage of reclamation, the desorption rate of phosphorus from wetland soils is high and may contribute to eutrophication of surrounding water bodies.