Ex situ sulphate reduction and methane oxidation rates of sediment at the rim of a vesicomyd clam colony in the Japan Deep Sea Trench (dive 956)

Sediment samples were collected from the rim of a large vesicomyid clam colony in the Japan Deep Sea Trench. Immediately after sample recovery onboard, the sediment core was sub-sampled for ex situ rate measurements. Sulfate reduction and anaerobic oxidation of methane were measured ex situ by the whole core injection method with three replicate measurements for each method. We incubated the samples at in situ temperature (1.5°C) for 48 hours with either 14C-methane (dissolved in water, 2.5 kBq) or carrier-free 35S-sulfate (dissolved in water, 50 kBq). Sediment was fixed in 25 ml sodium hydroxide (NaOH) solution (2.5%, w/v) or 20 ml ZnAc solution (20%, w/v) for AOM or SR, respectively. Turnover rates were measured as previously described (Kallmeyer et al., 2004; Treude et al., 2003).

本研究从日本海沟一处大型囊鳃蛤（vesicomyid clam）群落的边缘采集沉积物样品。样品在甲板回收后，即刻对沉积物岩芯进行分样以开展异位速率测定。本研究采用全岩芯注入法对硫酸盐还原（sulfate reduction, SR）与甲烷厌氧氧化（anaerobic oxidation of methane, AOM）进行异位测定，每种方法设置三次重复测量。将样品置于原位温度（1.5℃）下孵育48小时，分别添加溶于水的14C-甲烷（2.5 kBq）或无载体35S-硫酸盐（50 kBq）。分别使用25 mL质量体积分数为2.5%的氢氧化钠（NaOH）溶液、20 mL质量体积分数为20%的醋酸锌（ZnAc）溶液，对用于AOM与SR测定的沉积物进行固定。周转速率的测定方法参照已有文献报道（Kallmeyer等，2004；Treude等，2003）。