[Sediment and pore water nutrient characteristics in growing zones of Alternanthera philoxeroides in the Shiwuli River, Chaohu Lake].

In order to investigate the nitrogen and phosphorus characteristics of sediments and pore water in growing zones of aquatic macrophytes (Alternanthera philoxeroides), three classic representative sampling points in the planted Alternanthera philoxeroides fields (i. e. SP1, SP2 and SP3) and one reference site in the seldom vegetation (i. e. SP4) were chosen along the Shiwuli River, pouring into Chaohu Lake. Fifteen sediment cores were collected and sliced in-situ with a thickness of 2 cm, and a total of 80 samples were obtained. In the laboratory, both the contents of TN, TP, NH4(+) -N, NO3(-) -N, Fe/Al-P, Ca-P, organic matter in sediments and the concentrations of TN, TP, NH4(+) -N, NO3(-) -N and PO4(3-) -P in pore water were measured. And then, the vertical distribution profiles were illustrated and explored, and the correlations were also analyzed for the growing zones of Alternanthera philoxeroides. Through the comparison of profiles, it found that both nitrogen and phosphorus concentrations in pore water showed a rough similarity for three vegetation fields. At the surface sediment-overlying water interface, in general, there was a good agreement on the source-sink relationship for nitrogen and phosphorus corresponding to the SP1, SP2 and SP3. Study results showed that the vertical distribution of NH4(+) -N and NO3(-) -N in pore water within the depth of 0-18 cm could be characterized by using exponential functions such as Exp2PMod2 or Exp3P2 provided by OriginLab software, but PO4(3-) -P hardly ever did, implying that PO4(3-)-P might have a weaker regularity in solute diffusion than that of NH4(+) -N and NO3(-) -N.