Department of Marine Science and Convergence Technology, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea.
Department of Marine Science and Convergence Technology, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea; Marine Environmental Research Center, Korea Institute of Ocean Science & Technology, 385 Haeyang-ro, Yengdo-gu, Busan Metropolitan City 49111, Republic of Korea.
Sci Total Environ. 2019 May 15;665:752-761. doi: 10.1016/j.scitotenv.2019.02.058. Epub 2019 Feb 5.
We investigated sediment geochemistry, partitioning of organic carbon (C) 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 C oxidation pathway, accounting for 81.7% of total anaerobic C oxidation. Under the SR-dominated condition, HS 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 d) 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 CH accumulated, most P was bound to Fe and Al, which resulted in a low benthic P flux (0.03 mmol m d). 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 C oxidation pathways and P dynamics in coastal ecosystems.
我们研究了沉积物地球化学、铁还原（FeR）和硫酸盐还原（SR）氧化有机碳（C）的分配以及底栖磷（P）的释放，并结合沉积物中磷的形态，以阐明黄海Yeongsan 河口两个截然不同沉积物（即河口与湖沼）中的磷动态。在 Yeongsan 河河口的沉积物（St. YE）中，SR 主导着 C 氧化途径，占总厌氧 C 氧化的 81.7%。在 SR 主导的条件下，源自 SR 的 HS 会迅速与氧化铁反应，形成硫化铁，最终将与 Fe(III)结合的 P 释放到孔隙水中。YE 点增强的底栖 P 通量（0.24 mmol m d）占水柱初级生产力所需 P 的 80%。相比之下，在 Yeongsan 湖的湖沼沉积物（St. YL）中，由于 CH 积累水平较高，大部分 P 与 Fe 和 Al 结合，导致底栖 P 通量较低（0.03 mmol m d）。结果表明，通过人工堤坝频繁向河口排放相对贫磷的淡水可能导致河口生态系统中相对磷限制条件。因此，SR 主导的河口沉积物中底栖 P 的释放是沿海生态系统中 P 的重要内部来源。我们的结果表明，在河口建造大型堤坝会极大地改变沿海生态系统中的 C 氧化途径和 P 动态。
