杭州湾滨海湿地不同植被类型沉积物磷形态变化特征

研究了杭州湾滨海湿地不同植被类型下0-5 cm和10-20 cm沉积物总磷(TP)、无机磷(IP)、有机磷(OP)及其形态变化特征,揭示湿地植被演替对沉积物磷形态的影响.结果表明,沉积物TP,互花米草(MC)显著高于其他植被类型.在IP中,可溶性松散态磷(Soluble and loosely bound P,SL-Pi)含量光滩(CK)最小、MC最大;还原态可溶性磷(Reductant soluble P,RS-Pi)含量芦苇(LW)和MC显著高于CK和海三棱藤草(BC);钙磷(Ca-Pi)含量CK和BC显著大于LW和MC.在OP中,活性有机磷( Labile Po,L-Po)含量最低、中等活性有机磷(Moderately labile Po,ML-Po)含量最高、非活性有机磷(Nonlabile Po,NL-Po)处于中间水平.IP是磷素的主要形态、占TP的74％ -89％,而Ca-Pi又是IP的主要形态、于湿地沉积物淤积初期通过吸附沉淀作用存留.杭州湾湿地植被自然演替过程中不同植物生物量积累和营养物质循环过程的变化导致沉积物中磷形态的差异.植被演替初期,BC显著改变0-5 cm沉积物磷形态,对10-20 cm沉积物无显著影响;植物演替后期的LW和MC促使0-5 cm沉积物有机磷快速积累、10-20 cm沉积物有机磷小幅增加,同时促进Ca-Pi向可溶性、活性态磷转变.

Phosphorus fraction in the sediments from different vegetation type in hangzhou bay coastal wetlands

The effects of saltmarsh vegetation on phosphorus fractions in the sediments were studied in this paper. Phosphorus fractions in the two layer (0-5cm,10-20cm) sediments from four saltmarsh vegetation types(Bare flat, Scirpus mariqueter, Phragmites australis, Spartina alterniflora) were analyzed. The results indicated the impacts of vegetation succession on P fractions. The content of total phosphorus (TP) in the sediments from S.alterniflora(MC) habitats was higher than from the other vegetaion. The content of soluble and loosely bound P(SL-Pi) in was the lowest in bare flat(CK) and highest in sediments from MC haibitats. Similarly, the content of reductant soluble P(RS-Pi) in the sediments from P.australis(LW) and MC habitats were obviously higher than CK and S.mariqueter(BC). Adversely, the content of Ca-Pi in CK and BC habitatas sediments were significantly higher than LW and MC. The content of different organic P fractions was significantly different. In all vegetation types, the content of labile P(L-Po) was the lowest; the content of moderately labile P(ML-Po) was the highest; the content of nonlabile P(NL-Po) was at an intermediate level. Inorganic P covered up about 74%-89% of TP Ca-Pi,which was the main form of inorganic P, was retained by adsorbing and precipitating in the time of sediment deposition. The results suggested that biomass production and nutrient cycling processes with vegetation succession led to the difference of phosphorus forms. In early stage of succession, BC changed the P fractions of surface sediments significantly; but it imposed no obvious impact on subsurface sediments. In the later period, LW and MC promoted rapid accumulation of organic P in surface sediments but a litter less increase in subsurface sediments. At the same time, vegetation succession promoted Ca-Pi transforming to soluble and active P.