We investigated sediment geochemistry, partitioning of organic carbon (Corg) oxidation by iron reduction (FeR) and sulfate reduction (SR), and benthic phosphorus (P) release, together with the P speciation in the sediments to elucidate the P dynamics in two contrasting sediments (i.e., estuarine vs. limnetic) separated by a large dyke in the Yeongsan River estuary of the Yellow Sea. In the sediments of the Yeongsan River estuary (St. YE), SR dominated the Corg oxidation pathway, accounting for 81.7% of total anaerobic Corg oxidation. Under the SR-dominated condition, H2S derived from SR reacts quickly with iron oxides to form iron sulfides, which ultimately release the P bound to Fe(III) into the pore water. The enhanced benthic P flux (0.24 mmol m-2 d-1) at the YE site accounted for 80% of the P required for primary production in the water column. In contrast, in the limnetic sediments of the Yeongsan Lake (St. YL), where high levels of CH4 accumulated, most P was bound to Fe and Al, which resulted in a low benthic P flux (0.03 mmol m-2 d-1). The results suggest that the frequent discharge of relatively P-depleted freshwater into the estuary via the artificial dyke may result in relatively P-limiting conditions in estuarine ecosystems. As a result, benthic P release from the SR-dominated estuarine sediment is a significant internal source of P in the coastal ecosystem. Our results indicate that the construction of a large dyke at a river mouth greatly alters Corg oxidation pathways and P dynamics in coastal ecosystems.
A large artificial dyke greatly alters partitioning of sulfate and iron reduction and resultant phosphorus dynamics in sediments of the Yeongsan River estuary, Yellow Sea.
Sung-Uk An,J. Mok,Sung-Han Kim,J. Choi,J. Hyun
Published 2019 in Science of the Total Environment
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- Publication year
2019
- Venue
Science of the Total Environment
- Publication date
2019-02-05
- Fields of study
Medicine, Chemistry, Environmental Science
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Semantic Scholar, PubMed
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