Geochemical behavior of iron-sulfur coupling in coastal wetland sediments and its impact on heavy metal speciation and migration

Abstract

Coastal wetlands play a vital role in energy flow and material cycling, holding irreplaceable significance for global ecological security. This paper provides a comprehensive review of the geochemical behaviors of key elements, particularly iron and sulfur, in coastal wetland sediments, as well as their influence on the speciation and mobility of heavy metals. The findings indicate that the redox processes of iron, driven by both biotic and abiotic factors, are tightly coupled with sulfur redox reactions, thereby continuously regulating the speciation and mobility of heavy metals. This interplay serves as a critical determinant in the “source-sink” dynamics of heavy metals within coastal wetland sediments. A deeper understanding of these intricate mechanisms is essential for elucidating the operational principles of wetland ecosystems, assessing their ecological and environmental quality, and developing effective protection and management strategies. Future research should prioritize a deeper exploration of iron-sulfur cycling mechanisms, enhance the monitoring and evaluation of heavy metal transformation and migration processes, and investigate the environmental effects of secondary iron-sulfur minerals on the behavior and storage of heavy metals. These efforts will provide robust theoretical support for the restoration and sustainable management of coastal wetland ecosystems.