Forms of organic phosphorus in wetland soils

[摘要] Phosphorus (P) cycling in freshwater wetlands is dominated bybiological mechanisms, yet there has been no comprehensiveexamination of the forms of biogenic P (i.e., forms derived frombiological activity) in wetland soils.We used solution³¹P NMR spectroscopy to identify and quantify P forms insurface soils of 28 palustrine wetlands spanning a range ofclimatic, hydrogeomorphic, and vegetation types. Total Pconcentrations ranged between 51 and 3516 μg P g^-1,of which an average of 58% was extracted in a single-stepNaOH–EDTA procedure. The extracts contained a broadrange of P forms, including phosphomonoesters (averaging 24% ofthe total soil P), phosphodiesters (averaging 10% of total P),phosphonates (up to 4% of total P), and both pyrophosphate andlong-chain polyphosphates (together averaging 6% of totalP). Soil P composition was found to be dependant upon two keybiogeochemical properties: organic matter content and pH. For example,stereoisomers of inositol hexakisphosphate were detected exclusivelyin acidic soils with high mineral content, while phosphonates weredetected in soils from a broad range of vegetation andhydrogeomorphic types but only under acidic conditions. Converselyinorganic polyphosphates occurred in a broad range of wetland soils,and their abundance appears to reflect more broadly that of a"substantial" and presumably active microbial community witha significant relationship between total inorganic polyphosphatesand microbial biomass P. We conclude that soil P composition variesmarkedly among freshwater wetlands but can be predicted byfundamental soil properties.

[学科分类] 地球化学与岩石