Effects of <i>Vallisneria natans</i> on sediment phosphorus fractions and transfer during the growth period

Abstract

模拟湖泊系统构建了沉积物-水-苦草(Vallisneria natans)系统, 研究了在苦草生长期沉积物、水和苦草三相中磷含量的变化.结果表明:苦草在生长期, 能显著降低沉积物中各形态磷的含量, 沉积物总磷(TP)、NaOH提取磷(NaOH-P)、HCl提取磷(HCl-P)、无机磷(IP)和有机磷(OP)含量分别降低了65.71、39.06、11.65、52.86和11.28mg/kg.苦草对沉积物磷中IP的吸收效率要大于OP, 对NaOH-P的吸收效率要大于HCl-P.水中总磷浓度下降至0.04mg/L.沉积物中氧化还原电位(Eh)显著升高, 而pH呈下降趋势.沉积物TP、NaOH-P、HCl-P、IP和OP之间呈极显著正相关, 沉积物各形态磷含量与Eh呈不同程度的负相关, 与pH呈显著正相关, 与苦草根系表面积呈显著负相关.实验结束时, 苦草富集的磷为292.24mg, 沉积物、苦草和水中磷总量百分比分别为92.04%, 7.85%和0.12%.实验结果表明:苦草在生长期通过对沉积物Eh升高和pH降低的方式影响沉积物中磷的含量, 将沉积物和水中磷聚集于植物体内, 以降低沉积物磷向上覆水释放的风险.苦草对沉积物各形态磷的吸收率排序为NaOH-P >HCl-P;IP >OP。;Sediment-Water-V.natans in a simulated lake system was built to study phosphorus concentrations in sediment, water and V.natans during the growth period of Vallisneria natans.Simulation results indicated that different phosphorus concentrations in sediment were reduced significantly during the growth period of V.natans.Total phosphorus (TP), NaOH extracted phosphorus (NaOH-P), HCl extracted phosphorus (HCl-P), inorganic phosphorus (IP) and organic phosphorus (OP) were decreased by 65.71, 39.06, 11.65, 52.86 and 11.28 mg/kg, respectively.The IP absorption efficiency of V.natans was higher than that of OP, and the NaOH-P absorption efficiency was higher than that of HCl-P.The concentration of TP in water was decreased to 0.04 mg/L.Redox potential (Eh) was increased significantly but pH was decreased in sediment.There were significantly positive correlations among TP, NaOH-P, HCl-P, IP and OP.Different phosphorus fractions were negatively correlated with Eh at different levels, significantly positive-correlated with pH, and significantly negative-correlated with V.natans root area.Phosphorus ab-sorbed by V.natans was 292.24 mg at the end of the experiment.The phosphorus in sediment, V.natans and water were 92.04%, 7.85% and 0.12%, respectively.The result indicated that V.natans affected the concentrations of phosphorus in sediment through increasing redox potential and decreasing pH.V.natans reduced phosphorus release risk through uptaking phosphorus from water and sediment.The rank from high to low order of phosphorus absorption ratio by V.natans was NaOH-P, HCl-P, IP, and OP.