洱海河口湿地沉积物环境因子对磷形态空间分异的影响

研究不同深度沉积物磷形态的分布规律，探讨沉积物的理化性质及可提取态Fe、Al、Mn和Ca浓度对磷形态分布的影响，为深入理解沉积物内源磷的迁移转化过程和释放机理提供支持。在洱海罗时江湿地入口、湿地内部和湿地出口设置6个样点，采用柱状沉积物采样器采集每个样点20 cm以上的沉积柱样品，应用连续分级提取分析了湿地沉积物无机磷形态在水平和垂直方向的空间分异规律，讨论了理化指标、可提取态金属元素浓度等沉积物环境因子对无机磷形态空间分异的影响。结果表明:(1)洱海入湖河口湿地沉积物总无机磷(TIP)含量变化范围为1 360.24～2 093.66 mg/kg，其中残渣态磷(RP)含量最高，占比62.94%～85.18%，铁/铝结合态磷(Fe/Al-P)和钙结合态磷(Ca-P)占比分别为9.37%～25.97%和0.54%～11.42%，可交换态磷(EP)和水溶态磷(DP)含量最低，占比分别为0.94%～3.91%和0.22%～0.65%;(2)水平方向上TIP和各形态磷含量总体上均呈现沿水流方向逐渐递减的规律，其中TIP、EP、Fe/Al-P和Ca-P在出口位置含量稍高于湿地内部，垂直方向上DP、...

Effects of Environmental Factors on the Spatial Distribution of Phosphorus Fractions in the Estuarine Wetland Sediments of Erhai Lake

We investigated the Luoshijiang River wetland, located upstream of Erhai Lake, and analyzed the horizontal and vertical distribution of inorganic phosphorus fractions in the wetland sediments. Additionally, we examined the effects of environmental factors, including physicochemical indicators and concentrations of extractable metal elements on the spatial distribution of phosphorus fractions. The aim was to provide data to better understand the migration and release of endogenous phosphorus from the sediments. In July 2019, sediment samples were collected at six sites, representing the wetland entrance, interior and exit. The continuous stepwise extraction method was used to determine the different fractions of inorganic phosphorus in wetland sediments. The overlying water was also collected for determination of physiochemical parameters. Results show that: (1) The range of total inorganic phosphorus (TIP) in the sediments was 1360.24 - 2093.66 mg/kg, and residual phosphorus (RP) was highest (62.94% - 85.18%). The content of iron/aluminum combined phosphorus (Fe/Al-P) and calcium combined phosphorus (Ca-P) accounted, respectively, for 9.37%-25.97% and 0.54%-11.42% of the total TIP. The content of exchangeable phosphorus (EP) and water-soluble phosphorus (DP) were lowest, accounting, respectively, for 0.94%-3.91% and 0.22%-0.65% of the total TIP content. (2) Horizontally, the contents of TIP and various phosphorus fractions trended downward along the direction of water flow. The contents of TIP, EP, Fe/Al-P, and Ca-P at the outlet were slightly higher than those within the wetland. Vertically, the contents of DP, EP, Fe/Al-P, and RP were enriched in the surface layer and decreased with sediment depth, while the content of Ca-P was lower in the surface layer and enriched in the middle and bottom layers. (3) Redundancy analysis showed that extractable Mn, with the lowest content, was most explanatory (12.7%) for the distribution of phosphorus fractions (P<0.05). The influence of extractable Al and Mn, pH and ORP on the distribution of phosphorus fractions strengthened with sediment depth, whereas the effect of extractable Ca content on Ca-P distribution decreased with sediment depth.