The total amount and morphology of nitrogen and phosphorus in sediments have important environmental significance. The study of the ecological risk assessment of nitrogen and phosphorus in sediments is important to understand the environmental quality of water body in the basin. In this study, taking the Futunxi Basin of Fujian Province as an example, the single factor index and bioavailability coefficient method were used to evaluate the ecological risk of nitrogen and phosphorus in the sediments, and reveal the spatial change and environmental significance of the nitrogen and phosphorus forms. The results showed that different morphological components of the bio-available nitrogen were distributed as organic sulfide bound nitrogen (SOEF-N) > iron-manganese oxidized nitrogen (SAEF-N) > weak acid leached nitrogen (WAEF-N) > ion exchange nitrogen (IEF-N). The inorganic phosphorus included the highest proportion of metal oxide bound phosphorus (NaOH-P), followed by calcium bound phosphorus (HCl-P). The proportion of reduced phosphorus (BD-P) was even lower, and the proportion of weakly adsorbed phosphorus (NH4Cl-P) was the lowest. The results of single factor pollution index showed that the sediment nitrogen in the study area mainly caused moderate pollution and phosphorus mainly caused light pollution. By contrast, the results of the bioavailability index method indicated that nitrogen mainly caused light pollution, and phosphorus mainly caused clean pollution in sediments. Combined with the characteristics of social economy and environment in the study area, it can be inferred that the bioavailability index method based on comprehensive evaluation of total amount and morphology can better characterize the spatial change and ecological risk of nitrogen and phosphorus in sediments.

沉积物中氮和磷的总量和形态具有重要的环境意义。研究沉积物中氮，磷的生态风险评估对了解流域水体的环境质量具有重要意义。本研究以福建省富屯溪盆地为例，采用单因素指数和生物利用度系数法评价沉积物中氮，磷的生态风险，揭示氮，磷的空间变化及环境意义。磷的形式。结果表明，生物可利用氮的不同形态成分分布为：有机硫化物结合氮（SOEF-N）>铁锰氧化氮（SAEF-N）>弱酸浸出氮（WAEF-N）> 离子交换氮（IEF-N）。无机磷包括最高比例的金属氧化物结合磷（NaOH-P），其次是钙结合磷（HCl-P）。还原磷（BD-P）的比例更低，弱吸附磷（NH4Cl-P）的比例最低。单因素污染指数的结果表明，研究区的沉积物氮主要是中度污染，磷主要是轻度污染。相比之下，生物利用度指数法的结果表明，氮主要造成光污染，磷主要造成沉积物清洁污染。结合研究区域的社会经济和环境特征，