Phosphorus (P) is an important nutrient and has an important impact on global primary productivity. Presently, the dynamics of the P cycle in low sulfate, anoxic settings are largely unknown. In this study, the adsorption–desorption behavior of Fe-bound P, organic-P, loosely-bund P, detrital apatite P, and refractory P was described in the sulfate and methane transition zone (SMTZ) at site 973–4 in the cold-seep area of the Taixinan Basin, South China Sea. Results showed that the Fe-bound P and organic-P were influenced by sulfate-driven anaerobic oxidation of methane (SD-AOM) and metal-driven anaerobic oxidation of methane (MD-AOM), and subsequently, the Fe-bound P and organic-P were released as HPO₄²⁻ into the pore water. Meanwhile, significant increases were detected in authigenic carbonate fluorapatite (P_CFA) and vivianite within the MD-AOM zone, which indicate that this zone is an important P-sink area. The MD-AOM plays an important role in the formation of P_CFA and vivianite because MD-AOM provide the necessary HPO₄²⁻ and Fe²⁺ for the formation of these minerals. Our findings have major implications for understanding the P cycle in low sulfate, anoxic settings and are important for understanding the influence of MD-AOM on the phosphate cycle.

磷（P）是重要的营养素，对全球初级生产力具有重要影响。目前，在低硫酸盐，缺氧环境中P循环的动力学很大程度上未知。在这项研究中，Fe结合的P，有机P，松散的P，碎屑的磷灰石P和难熔的P在硫酸盐和甲烷过渡区（SMTZ）973-4处的吸附-解吸行为被描述。南海泰新南盆地的寒区。结果表明，Fe结合的P和有机P受硫酸盐驱动的甲烷厌氧氧化（SD-AOM）和金属驱动的甲烷厌氧氧化（MD-AOM）以及随后的Fe结合的P和有机磷的影响。有机-P被释放为HPO ₄ ^2-进入毛孔水。同时，在MD-AOM区域内发现自生碳酸盐氟磷灰石（P _CFA）和云母明显增加，这表明该区域是重要的P汇区。MD-AOM在P _CFA和堇青石的形成中起着重要作用，因为MD-AOM提供了这些矿物的形成所必需的HPO ₄ ^2-和Fe ²⁺。我们的发现对于理解低硫酸盐，缺氧环境中的P循环具有重要意义，对于理解MD-AOM对磷酸盐循环的影响也很重要。