典型岩溶湿地表层沉积物中磷的形态及分布特征研究

Occurrence Form and Distribution Characteristics of Phosphorus in Surface Sediments of Typical Karst Wetlands

为探析普者黑岩溶流域不同类型湿地表层沉积物中各形态磷的含量特征及风险,以普者黑岩溶流域为研究区,运用抓斗式底泥采样器在枯、丰、平3个水期对流域内4种湿地的表层沉积物进行采样。采用国家标准方法及四步连续提取法对沉积物中全磷(S−TP)及磷形态的含量进行测定,分析弱吸附态磷(NH_(4)Cl−P)、可还原态磷(BD−P)、铁铝结合态磷(NaOH−P)、钙结合态磷(HCl−P)及残渣磷之间的相关性。结果表明:普者黑岩溶流域表层沉积物S−TP的分布情况在506~846 mg/kg,对于不同类型湿地表现为河流湿地>沼泽湿地>湖泊湿地>库塘湿地。普者黑岩溶流域除库塘湿地外的其他3种湿地表层沉积物中不同形态磷含量分布情况为NaOH−P>残渣磷>BD−P>HCl−P>NH_(4)Cl−P,而库塘湿地中的残渣磷含量大于NaOH−P。Pearson相关系数表明,沉积物中S−TP含量的增加主要来自NaOH−P;其次是HCl−P,部分来自于残渣磷,水体中总磷(W−TP)和正磷酸盐(SRP)含量主要来自于残渣磷、S−TP和BD−P。残渣磷与NH_(4)Cl−P、BD−P、NaOH−P、HCl−P之间相关性较小,说明其来源具有差异性。

To explore the characteristics and risks of various forms of phosphorus in surface sediments of different wetlands in Puzhehei karst watershed.Taking Puzhehei karst watershed as the research area,surface sediments of 4 wetlands in the watershed were sampled by grab-type sediment sampler in dry,rich and flat water periods.The contents of total phosphorus(S−TP)and phosphorus forms in sediments were determined by national standard method and four-step continuous extraction method.The correlations among weakly adsorbed phosphorus(NH_(4)Cl−P),reducible phosphorus(BD−P),iron-aluminium bound phosphorus(NaOH−P),calcium bound phosphorus(HCl−P)and residual phosphorus were analyzed.The results showed that the distribution of S−TP in the surface sediment of Puzhehei karst basin is 506 mg/kg–846 mg/kg.For different types of wetlands,it is river wetland>swamp wetland>lake wetland>reservoir wetland.Distribution of different forms of phosphorus in surface sediments of 3 wetlands in Puzhehei karst basin except reservoir wetland was NaOH−P>residual phosphorus>BD−P>HCl−P>NH_(4)Cl−P,while the residual phosphorus content in reservoir wetland was higher than NaOH−P.Pearson correlation coefficient shows that the increase of S−TP content in sediment mainly comes from NaOH−P,followed by HCl−P,part of which comes from residual phosphorus.The content of total phosphorus(W−TP)and orthophosphate(SRP)in water mainly comes from residual phosphorus,S−TP and BD−P.There is little correlation between residual phosphorus and NH_(4)Cl−P,BD−P,NaOH−P,HCl−P,which indicates that the source of residual phosphorus is different.