Inorganic sulfur cycles in sediments of the Pearl River Estuary: Processes, mechanisms, and isotopic indicators

Yin, Xijie1; Lin, Yunpeng1,3; Li, Yunhai1,2; Wang, Liang1; Sun, Zhilei4; Li, Guogang5

2023-01-05

10.1016/j.ecss.2022.108185

ESTUARINE COASTAL AND SHELF SCIENCE   Impact Factor & Quartile

0272-7714

1096-0015

The burial of inorganic sulfur is one of the important components in the global sulfur cycle. In this study, the cycling of inorganic sulfide species and the underlying control mechanisms were examined in sediments found in distinct sub-regions of the Pearl River Estuary (PRE). Specifically, the content and isotopic composition of SO42- , acid-volatile sulfides (AVS), and pyrite were determined, along with sedimentary sulfate reduction rates (SRR). The results show that the formation of iron sulfides (such as AVS and pyrite) was mainly controlled by the content of available reactive iron in the sediments of the PRE, and therefore formed mainly in the shallow sediments, with little variation in the deeper parts of the sediments. The delta S-34 values of AVS and SO42- increased synchronously with depth in the middle and lower part of the sediment, indicating a closed diagenetic envi-ronment. In contrast, the delta S-34 value of pyrite only increased slowly with depth in the case of a small portion of AVS converted to pyrite, which was controlled by the burial time. There are obvious differences in the formation and burial of pyrite in sediments of different sub-regions of the PRE. The surface layer of stations QA and HQ in the upper estuary and brackish coast was an open environment due to sedimentary reworking, and the contents of AVS and pyrite in the sediment was extremely low due to re-oxidation, while the oxidation of S-32-rich H2S also resulted in lower delta S-34 values of sulfate in the sediment pore water than in the overlying seawater. Station GS in the estuarine mouth had a much higher percentage of AVS converted to pyrite in the sediments than that at stations QA and HQ due to the relatively long burial time. In addition, near the sulfate methane transition zone (SMT), only the estuarine mouth (station GS) produced iron sulfides (AVS) synchronously with the anaerobic oxidation of methane (AOM), and then converted to pyrite gradually; in contrast, the effect of AOM on the formation of iron sulfides in the sediments of the upper estuary and the brackish coast was almost negligible. The results show that the contribution of AOM processes to the final burial of inorganic sulfur is generally small in PRE.

Inorganic sulfur cycles Sediment Sulfur isotopes Pearl River Estuary (PRE)

SCI

English

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National Natural Science Foundation of China[41976050] ; Scientific Research Foundation of the Third Institute of Oceanography, MNR, China["TIO2016046","TIO2019028"]

Marine & Freshwater Biology ; Oceanography

Marine & Freshwater Biology ; Oceanography

WOS:000916176900002

ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

PLANT & ANIMAL SCIENCE

Web of Science

1.Minist Nat Resources, Inst Oceanog 3, Xiamen, Peoples R China
2.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Geol, Qingdao, Peoples R China
3.Southern Univ Sci & Technol, Dept Ocean Sci & Engn, Shenzhen, Peoples R China
4.Minist Nat Resources, Qingdao Inst Marine Geol, Key Lab Gas Hydrate, Qingdao, Peoples R China
5.Minist Nat Resources, North China Sea Adm, Xiamen, Peoples R China

Yin, Xijie,Lin, Yunpeng,Li, Yunhai,et al. Inorganic sulfur cycles in sediments of the Pearl River Estuary: Processes, mechanisms, and isotopic indicators[J]. ESTUARINE COASTAL AND SHELF SCIENCE,2023,280.

Yin, Xijie,Lin, Yunpeng,Li, Yunhai,Wang, Liang,Sun, Zhilei,&Li, Guogang.(2023).Inorganic sulfur cycles in sediments of the Pearl River Estuary: Processes, mechanisms, and isotopic indicators.ESTUARINE COASTAL AND SHELF SCIENCE,280.

Yin, Xijie,et al."Inorganic sulfur cycles in sediments of the Pearl River Estuary: Processes, mechanisms, and isotopic indicators".ESTUARINE COASTAL AND SHELF SCIENCE 280(2023).