贵州草海沉积物中磷的形态分布及释放通量研究

Formation distribution and release fluxes of phosphorus in sediments of Caohai Lake,Guizhou Province

磷是湖泊水体富营养化关键性限制因子之一,为了解草型湖泊沉积物中磷形态的赋存特征及其释放风险,以典型草型湖泊——贵州草海为研究对象,运用化学连续提取法和孔隙水扩散模型分析了草海沉积物中磷的形态及释放通量。结果表明:草海沉积物TP含量为563.75~982.40 mg/kg,平均含量为(722.97±71.38)mg/kg,为3级污染,沉积物TP具有明显的空间差异,人类活动强度大的区域TP含量较高;磷形态含量依次为NaOH-NRP>Res-P>NaOH-SRP>BD-P>HCl-P>NH 4Cl-P,其中活性磷(NaOH-NRP、BD-P和NH 4Cl-P)是草海磷的主要存在形态,占沉积物TP的58.05%;释放通量为0.03~0.08 mg/(m^(2)·d),表明草海的磷自沉积物向上覆水扩散,表现为“源”。研究发现草海有机磷的占比较高,潜在释放风险大;草海沉积物磷含量和释放通量均较藻型湖泊的低。研究成果对草型湖泊的保护管理具有重要意义。

Phosphorus is one of the limited factors for eutrophication of lakes.In order to understand the occurrence characteristics and release risks of phosphorus forms in sediment of the grass-type lakes,the phosphorus forms and release fluxes in sediments of Caohai Lake of Guizhou Province were analyzed by sequential extraction and pore water diffusion model.The results showed that the content of TP in Caohai Lake sediments was 563.75~982.40 mg/kg,and the average content was(722.97±71.38)mg/kg,which was a third-order pollution.TP has significant spatial differences,with higher TP content in areas with high human activity intensity.The rank of different phosphorus forms content was NaOH-NRP>Res-P>NaOH-SRP>BD-P>HCl-P>NH 4Cl-P.The active phosphorus(NaOH-NRP,BD-P and NH 4Cl-P),which accounts for 58.05%of TP in sediments,was the main form of phosphorus in Caohai Lake.And the release fluxes were 0.03~0.08 mg/(m^( 2)·d).It indicated that the phosphorus in Caohai Lake spread from the sediment to the overlying water,showing as"source".In this study,we found that the proportion of organic phosphorus in Caohai Lake was relatively high,and the potential release risk was high.The phosphorus content and release flux in the sediments in Caohai Lake were lower than those of the algae-type lakes.The results have great significance for the conservation and management of the grass-type lakes.