Abstract The risk of hydrogen sulfide (H2S) production can be a challenge in marine land-based recirculating aquaculture systems (RAS). Hydrogen sulfide is a toxic gas that can cause massive fish mortality even at low concentrations, and in addition, serious odour problems in the surroundings. It is a bacterial by-product originating from the degradation of organic matter in sulfur-rich waters such as marine waters. In order to hinder H2S production in marine land-based RAS, more information on the H2S production conditions and the associated microbiology is needed. In this study, the production of H2S from rainbow trout (Oncorhynchus mykiss) organic waste was examined using a novel H2S measurement method under a range of salinities (0, 5, 10, 15, 25 and 35 g/L) in anaerobic mixed reactors, and the microbial communities as well as abundance of sulfate reducing bacteria (SRB) were characterized. The maximum H2S concentration increased from 23.1 ± 8.2 mg H2S/L at 0 g/L salinity to 153.9 ± 34.1 mg H2S/L at 35 g/L salinity. Similarly, the H2S production rate increased from 5.6 ± 0.2 at 0 g/L salinity to 26.4 ± 12.7 mg of H2S produced per day at 35 g/L salinity. The highest H2S production was recorded after increased availability of volatile fatty acids, which were produced by fermentative bacteria from phyla Firmicutes and Bacteroidetes that dominated the microbial communities after day 5. The traditional sulfate reducing bacteria (SRB) were found only at 0 and 5 g/L salinity, while at higher salinities, H2S production was carried out by novel unquantifiable SRB. The results demonstrate that H2S can be a pronounced problem in marine RAS, although it can be controlled through preventing anaerobic conditions within the system.

中文翻译：

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咸水中硫酸盐可用性的增加促进了鱼类有机废物中硫化氢的产生

摘要 硫化氢 (H2S) 产生的风险可能是海洋陆基再循环水产养殖系统 (RAS) 的一个挑战。硫化氢是一种有毒气体，即使在低浓度下也会导致大量鱼类死亡，此外，还会对周围环境造成严重的气味问题。它是一种细菌副产品，源于富含硫的水域（如海水）中有机物的降解。为了阻止海洋陆基 RAS 中 H2S 的产生，需要更多关于 H2S 产生条件和相关微生物学的信息。在这项研究中，在厌氧混合反应器中，在一系列盐度（0、5、10、15、25 和 35 克/升）下，使用新型 H2S 测量方法检查了虹鳟鱼 (Oncorhynchus mykiss) 有机废物的 H2S 生产, 并对微生物群落以及硫酸盐还原菌 (SRB) 的丰度进行了表征。最大 H2S 浓度从 0 g/L 盐度下的 23.1 ± 8.2 mg H2S/L 增加到 35 g/L 盐度下的 153.9 ± 34.1 mg H2S/L。同样，H2S 的产生率从 0 g/L 盐度下的 5.6 ± 0.2 增加到 35 g/L 盐度下每天产生的 H2S 26.4 ± 12.7 mg。在挥发性脂肪酸的可用性增加后记录了最高的 H2S 产量，挥发性脂肪酸是由厚壁菌门和拟杆菌门的发酵细菌产生的，它们在第 5 天后主导微生物群落。传统的硫酸盐还原菌 (SRB) 仅在 0 和 5 g 时被发现/L 盐度，而在较高盐度下，H2S 的产生是由新型的无法量化的 SRB 进行的。结果表明 H2S 可能是海洋 RAS 中的一个明显问题，