Trends with water depth for key characteristics of the sediment.

<p>Values are averages for the total analyzed Unit I section per multicore. The grey area indicates the part of the water column that is oxic.</p

Sediment profiles of total P, CaCO₃, Mn, C_org (organic C), S, Fe, Mo, Al and C_org/P_tot.

<p>The sediments at stations 10, 7617, 8, 7620 and 5 are Unit I sediments unless indicated otherwise. Note the difference in sampling resolution. Water depth is given in meters below sea surface (mbss).</p

Solid phase phosphorus fractions for all stations (in µmol/g).

<p>The fractions are exchangeable P (Ex-P), detrital P (Detr-P), authigenic Ca-P (Auth-P), Organic P (Org-P) and Fe-bound P (Fe-P), as determined with the SEDEX extraction procedure <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101139#pone.0101139-Ruttenberg3" target="_blank">[10]</a>. All sediments were Unit I sediments except the turbidite and Unit II sediments at station 5. Note the differences in depth scale for each station. Water depth is given in meters below the sea surface (mbss).</p

The P mass balance of the Black Sea with values in x 10⁷ mol P/yr.

<p>The fluxes related to the Sea of Marmara are excluded as their effect is minimal <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101139#pone.0101139-Teodoru1" target="_blank">[35]</a>. The Black Sea is divided into two areas: the shelf with generally oxic bottom waters (<200 m water depth) and the basin with anoxic bottom waters (>200 m water depth). The relative P fractions are based on values below 5 cm depth to limit the effect of short-term burial on total P burial. Based on this balance, 11×10⁷ mol P is added to the water column on a yearly basis.</p

Data_Sheet_1_Impact of the Major Baltic Inflow in 2014 on Manganese Cycling in the Gotland Deep (Baltic Sea).PDF

<p>The deep basins of the Baltic Sea, including the Gotland and Landsort Deeps, are well-known for the exceptional occurrence of sedimentary Mn carbonate. Although the details of the mechanisms of Mn carbonate formation are still under debate, a close relationship with episodic major Baltic inflows (MBIs) is generally assumed, at least for the Gotland Basin. However, the few studies on Mn cycling during MBIs suffer from a limited temporal resolution. Here we report on Mn dynamics in the water column and sediments of the Gotland Deep following an MBI that entered the Baltic Sea in December 2014. Water column profiles of dissolved Mn were obtained at a monthly to bi-monthly resolution between February 2015 and March 2017 and revealed an impact of the MBI on the Gotland Deep bottom waters beginning in March 2015. Water column profiles and budget estimates provided evidence for remarkable losses of dissolved Mn associated with the enhanced deposition of Mn oxide particles, as documented in sediment trap samples and surface sediments. In July 2015, subsequent to the nearly full oxygenation of the water column, clear signals of the re-establishment of bottom water anoxia appeared, interrupted by a second inflow pulse around February 2016. However, dissolved Mn concentrations of up to 40 μM in the bottom waters in June 2016 again indicated a pronounced reduction of Mn oxide and the escape of dissolved Mn back into the open water column. The absence of substantial amounts of Mn carbonate in the surface sediments at the end of the observation period suggested that the duration of bottom water oxygenation plays an important role in the formation of this mineral. Data from both an instrumental time series and a dated sediment core from the Gotland Deep supported this conclusion. Enhanced Mn carbonate formation occurred especially between the 1960s and mid-1970s, when several MBIs caused a long-lasting oxygenation of the water column. By contrast, Mn carbonate layers were much less pronounced or even missing after single MBIs in 1993, 2003, and 2014, each of which provided a comparatively short-term supply of O₂ to the deeper water column.</p

Key characteristics of the sampled stations.

<p>*: At station 5, the assignment of the interval from 33–35 cm to unit II is tentative and is based on visual observations.</p

Sources of data for the P budget for the Black Sea in x 10⁷ mol/yr, unless noted differently.

<p>Mean values for the relative P fractions were calculated from the P fractionation data (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101139#pone-0101139-g005" target="_blank">Fig 5</a>).</p><p>*: based on sediments from 5 cm sediment depth downwards.</p

Pore water profiles of Fe²⁺, Mn²⁺, SO₄²⁻, PO₄, NH₄⁺, H₂S and alkalinity for three stations.

<p>Note the differences in depth resolution. Water depth is given in meters below sea surface (mbss). Bottom water samples are indicated with open symbols.</p

Black Sea map including the station locations and bathymetry in m below sea surface (mbss).

<p>Black Sea map including the station locations and bathymetry in m below sea surface (mbss).</p

Solid phase iron fractions for all stations (in µmol/g).

<p>The fractions, as determined with the sequential extraction procedure of Poulton and Canfield <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101139#pone.0101139-Poulton1" target="_blank">[29]</a>, are carbonate-associated Fe (Fe-Carb) magnetite (Fe-Mag), Fe extracted with a hydroxylamine-HCl extraction (Fe-Ox1, targets amorphous Fe-oxides) and Fe extracted in the dithionite extraction (Fe-Ox2, targets crystalline Fe-oxides). All sediments were Unit I sediments except for the Unit II sediments at station 7620 and the turbidite and Unit II sediments at station 5. Note the differences in depth scale for each station. Water depth is given in meters below sea surface (mbss).</p