闽江口湿地沉积物各形态磷分布特征及风险评价

为探究湿地植被、理化性质等对沉积物磷的各赋存形态的影响,评价闽江口湿地污染程度和潜在环境风险。2017年在闽江河口湿地由陆向海选取4个采样点,用SMT法提取各形态磷,测定分析了闽江口湿地沉积物各形态磷变化规律并进行风险评价。结果表明:沉积物中有机磷含量为0.176～0.369mg/g,约占总磷的32.03%;而无机磷含量为0.308～0.666mg/g,占总磷66.49%;总磷含量为0.491～0.998mg/g,其污染指数为0.819～1.618,总体上为轻度污染。各形态磷在不同植被类型沉积物中含量分布不同,其中沉积物有机磷含量芦苇最高,扁穗莎草最低;无机磷中的钙磷含量则是互花米草最少,短叶茳芏和扁穗莎草明显高于其他植被类型;而铁铝磷含量是互花米草远高于其他植物;因总磷受无机磷影响较大,以致无机磷含量与总磷含量分布相似,均是扁穗莎草最高,芦苇最低。沉积物中钙磷与容重呈极显著负相关,与含水率呈极显著正相关,有机磷含量与有机质呈极显著正相关;总磷与含水率呈极显著正相关,与电导率呈显著负相关。以上现象可能由植被类型与生长阶段、理化性质、陆源物质、水文环境、凋落物、人类生产活动等多个因素的综合作用所导致。

Distribution Characteristics and Risk Assessment of Phosphorus Speciation in the Sediments of Min River Estuary Wetland

To evaluate the wetland pollution and potential environmental risks in Min River Estuary, the effects of wetland vegetations and physicochemical properties on the distribution of sediment phosphorus were explored. From land to sea in the research area, sediments of four sites with different wetland vegetation types (Spartina alterniflora, Phragmites australis, Cyperus malaccensis and Cyperus compressus respectively) were sampled in 2017, and then phosphorus speciations were analyzed using SMT method. In all four vegetation types wetlands, organic phosphorus (OP) accounted for averagely 32.03% of total phosphorus (TP), between 0.176~0.369 mg/g. Inorganic phosphorus (IP) accounted for averagely 66.49% of TP, between 0.308~0.666 mg/g. TP concentrations were from 0.491~0.998 mg/g, which were considered as moderate pollution level with the pollution index (moderate polluted 0.819~1.618). Results suggested that the distribution of phosphorus speciations varied from wetland vegetation types. The highest concentration of OP was found in the Phragmites australis wetland, and the lowest in Cyperus compressus. The Ca-P concentrations were obviously higher in Cyperus malaccensis and Cyperus compressus wetlands than in Spartina alterniflora. However, the Fe/Al-P concentrations were significantly higher in Spartina alterniflora wetland compared to other wetlands. Since TP was strongly related to IP, the trends of TP and IP were similar:The highest concentration in Cyperus compressus wetland and the lowest in Phragmites australis wetland. Finally, the Ca-P concentrations showed the significantly negative correlation with bulk density, and the positive correlation with water contents. TP concentrations were significantly negatively correlated to conductivity, and positively correlated to water contents. All these phenomenon described could relate to the comprehensive effects of vegetation types and growth stages, physicochemical properties, terrestrial materials, hydrological environment, litters, and human production activities.