The sulfate reduction process plays an important role in the early diagenesis of organic matter in the estuarine and coastal sediments. In this study, the sulfate reduction rates (SRR) were determined by the ³⁵SO₄²⁻ radioactive tracer method, and the SO₄²⁻, CH₄, Cl⁻ of sediment porewater and total organic carbon (TOC), temperature, and redox potential (Eh) of sediment were determined simultaneously at three stations (QA, HQ, and GS) in different sedimentary environments of the Pearl River Estuary to study the sulfate reduction process and its important role in organic matter mineralization. The results show that SRR was mainly controlled by the content and availability of organic matter in sediments of the Pearl River Estuary. The consumption of sulfate mainly included the organic matter mineralization on the upper sediments and the anaerobic oxidation of methane (AOM) driven by sulfate in the sulfate-methane transition zone (SMT), which formed two peaks in the SRR profile, respectively (stations HQ and GS). Affected by physical disturbance, there was only one SRR peak formed above the SMT at station QA. The results of flux calculations for AOM and sulfate reduction show that the contributions of AOM to total sulfate reduction were 7.04 %, 5.46 %, and 42.0 % at stations QA, HQ, and GS, respectively, which were also controlled by the content and availability of organic matter in sediments. The depths of SMT in sediments of stations QA, HQ, and GS were 25, 30, and 213 cm, respectively, which were controlled by the input of organic matter and sulfate concentration in sediments. The calculation results show that total fluxes of sulfate reduction were 22.7, 35.3, and 3.9 mmol m⁻² d^-l at stations QA, HQ, and GS, respectively, and the rates of organic carbon mineralization by sulfate reduction were 45.4, 70.6, and 7.8 mmol m⁻² d^-l. In the estuarine mouth (station GS) with relatively weak hydrodynamic force and deep water, the burying efficiency of organic matter in sediment was higher than that in the brackish coast (station HQ); whereas the burial efficiency of organic matter in sediment cannot be comprehensively estimate in the upper estuary (station QA) due to the existence of the fluid mud layer. These findings contribute to a comprehensive understanding of the biogeochemical cycling process of sulfate and methane in sediments of the Pearl River Estuary.

硫酸盐还原过程在河口和沿海沉积物中有机质的早期成岩作用中起着重要作用。在本研究中，硫酸盐还原率 (SRR) 由³⁵ SO ₄ ^2-放射性示踪剂法和 SO ₄ ^2-、CH ₄、Cl ^-测定。在珠江口不同沉积环境的三个站点（QA、HQ和GS）同时测定沉积物孔隙水和总有机碳（TOC）、温度和氧化还原电位（Eh），以研究硫酸盐还原过程及其在有机质矿化中的重要作用。结果表明，SRR主要受珠江口沉积物中有机质含量和有效性控制。硫酸盐的消耗主要包括上层沉积物的有机质矿化和硫酸盐-甲烷过渡带（SMT）中由硫酸盐驱动的甲烷（AOM）的厌氧氧化，分别在SRR剖面上形成了两个峰（站HQ和 GS）。受物理干扰的影响，在 QA 站的 SMT 上方仅形成了一个 SRR 峰值。AOM和硫酸盐还原的通量计算结果表明，QA、HQ和GS站的AOM对总硫酸盐还原的贡献分别为7.04%、5.46%和42.0%，这也受含量和可用性控制沉积物中的有机质。QA、HQ和GS站沉积物中SMT的深度分别为25、30和213 cm，受沉积物中有机质和硫酸盐浓度的输入控制。计算结果表明，硫酸盐还原的总通量分别为22.7、35.3和3.9 mmol·m 也受沉积物中有机物的含量和可利用性控制。QA、HQ和GS站沉积物中SMT的深度分别为25、30和213 cm，受沉积物中有机质和硫酸盐浓度的输入控制。计算结果表明，硫酸盐还原的总通量分别为22.7、35.3和3.9 mmol·m 也受沉积物中有机物的含量和可利用性控制。QA、HQ和GS站沉积物中SMT的深度分别为25、30和213 cm，受沉积物中有机质和硫酸盐浓度的输入控制。计算结果表明，硫酸盐还原的总通量分别为22.7、35.3和3.9 mmol·m^-2 d ^{-l 分别}在 QA、HQ 和 GS 站，硫酸盐还原的有机碳矿化速率分别为 45.4、70.6 和 7.8 mmol m ^-2 d ^-l。水动力较弱、水深的河口河口（GS站），沉积物中有机质埋藏效率高于咸水海岸（HQ站）；而上河口（QA站）由于泥浆层的存在，沉积物中有机质的埋藏效率无法综合估算。这些发现有助于全面了解珠江口沉积物中硫酸盐和甲烷的生物地球化学循环过程。