Geochemical responses of iron and sulfur in coastal soils to sea level rise: A simulation study

LI Sha; WANG Mingjun; GOU Zhihao; SUI Jiawei; LI Tie; ZHU Maoxu

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LI Sha，WANG Mingjun，GOU Zhihao, et al. Geochemical responses of iron and sulfur in coastal soils to sea level rise: A simulation study[J]. Haiyang Xuebao，2026, 48(x)：1–10

Citation:

LI Sha，WANG Mingjun，GOU Zhihao, et al. Geochemical responses of iron and sulfur in coastal soils to sea level rise: A simulation study[J]. Haiyang Xuebao，2026, 48(x)：1–10

Citation:

LI Sha，WANG Mingjun，GOU Zhihao, et al. Geochemical responses of iron and sulfur in coastal soils to sea level rise: A simulation study[J]. Haiyang Xuebao，2026, 48(x)：1–10

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Geochemical responses of iron and sulfur in coastal soils to sea level rise: A simulation study

Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China

Received Date: 2026-04-19
Rev Recd Date: 2026-05-07

Available Online: 2026-05-27

Abstract

Abstract

Seawater immersion caused by sea-level rise can significantly alter the redox conditions of coastal soils and affect the geochemical processes of iron (Fe) and sulfur (S). To investigate the geochemical response of Fe and S in soils under progressive seawater immersion, a 160-d soil column incubation experiment was conducted using soils with different reactive Fe and organic carbon contents. Seawater table was progressively raised to simulate sea-level rise, and the changes in pore water dissolved Fe (DFe), dissolved sulfide, and solid-phase reactive Fe and sulfide species were analyzed. The results showed that after seawater immersion, DFe concentrations in pore water significantly increased in all soil treatments, while dissolved sulfide remained at relatively low levels overall. In soils with low reactive Fe content, only minor accumulation of total reduced inorganic sulfur (TRIS) occurred in the deeper layers. In contrast, reactive Fe-rich red soil exhibited faster and higher DFe accumulation, as well as more pronounced TRIS accumulation. Higher organic matter content further promoted dissimilatory iron reduction and sulfate reduction, and shortened the initiation time of sulfate reduction. Distinct vertical distributions of DFe and TRIS were observed: DFe concentrations in the middle layer were generally higher than those in the bottom and top layers. TRIS was dominated by elemental sulfur (S⁰) and acid-volatile sulfide (AVS) in all treatments, with limited formation of pyrite. The different response times of dissimilatory iron reduction and sulfate reduction to seawater immersion, together with the contents of reactive Fe and organic matter, jointly control the transformation and vertical differentiation of Fe and S in soils. Long-term progressive seawater inundation not only shifts the sulfide accumulation layer upward but also weakens the “rusty sink” effect of reactive Fe on organic carbon protection, while simultaneously affecting the chemistry of both groundwater and surface water.
- Sea-level rise,
- iron dissimilatory reduction,
- sulfate reduction,
- sulfide,
- dissolved iron,
- organic carbon

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References(34)

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