Benthic phosphorus cycling within the Eurasian marginal sea ice zone

Abstract

The Arctic Ocean region is currently undergoing dramatic changes, which will likely alter the nutrient cycles that underpin Arctic marine ecosystems. Phosphate is a key limiting nutrient for marine life but gaps in our understanding of the Arctic phosphorus (P) cycle persist. In this study, we investigate the benthic burial and recycling of phosphorus using sediments and pore waters from the Eurasian Arctic margin, including the Barents Sea slope and the Yermak Plateau. Our results highlight that P is generally lost from sediments with depth during organic matter respiration. On the Yermak Plateau, remobilization of P results in a diffusive flux of P to the seafloor of between 96 and 261 µmol m −2 yr −1 . On the Barents Sea slope, diffusive fluxes of P are much larger (1736–2449 µmol m −2 yr −1 ), but these fluxes are into near-surface sediments rather than to the bottom waters. The difference in cycling on the Barents Sea slope is controlled by higher fluxes of fresh organic matter and active iron cycling. As changes in primary productivity, ocean circulation and glacial melt continue, benthic P cycling is likely to be altered with implications for P imported into the Arctic Ocean Basin. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning’.

Benthic Carbon Remineralization and Iron Cycling in Relation to Sea Ice Cover Along the Eastern Continental Shelf of the Antarctic Peninsula

“…Below the iron reduction zone, lower DFe:PO 4 3− ratios were observed suggesting the presence of a DFe sink (FeS formation) and the continuing release of PO 4 3− from organic matter remineralization (Niewöhner et al., 1998; Schulz et al., 1994; Wunder et al., 2021) and/or desorption from Fe‐minerals. Similar trends of pore‐water profiles of PO 4 3− and DFe have previously been observed in the Arctic marginal sea ice zone (Tessin et al., 2020), in the Peruvian oxygen minimum zone (Noffke et al., 2012), in sediments off Namibia (Küster‐Heins, de Lange, et al., 2010; Küster‐Heins, Steinmetz, et al., 2010) and in shelf sediments of the sub‐Antarctic island of South Georgia (Wunder et al., 2021).…”

The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning

“…As the sea ice reduction will continue northward and modify the ocean primary production, patterns of the benthic-pelagic phosphorus cycle are also likely to change. By comparing sediments and porewaters from the Barents Sea slope and the Yermak Plateau, Tessin et al [45] conclude that increased delivery of labile organic matter in response to elevated surface productivity will increase the oxidant demand and Fe remobilization within sediments and cause the Yermak Plateau to shift towards the conditions observed in the Barents Sea slope. Increased organic carbon fluxes on the Barents Sea slope may result in large fluxes of P from sediments to bottom waters, as a large stock of P has been accumulated in surface sediments.…”

Arctic Continental Margin Sediments as Possible Fe and Mn Sources to Seawater as Sea Ice Retreats: Insights From the Eurasian Margin

“…After 24 hr, sediment was then centrifuged (3,000 rpm for 2 min) and analyzed using a Turner Designs AU‐10 fluorometer before and after acidification with 100 μl 0.3 M HCl. Results for most study locations are previously published in Oleszczuk et al (2019) and Tessin et al (2020).…”

“…Results for most study locations are previously published in Oleszczuk et al (2019) and Tessin et al (2020).…”