ALBERT

Description: Concentrations of heme b were determined in a mesocosm experiment situated in Gullmar Fjord off Sweden. The mesocosm experiment lasted for ca. one hundred days and was characterised by the growth of a primary nutrient replete and a secondary nutrient deplete phytoplankton bloom. Heme b varied between 40 ± 10 pmol/l in the prebloom period up to a maximum of 700 ± 400 pmol/l just prior to the time of the primary chlorophyll a maximum. Thereafter, heme b concentrations decreased again to an average of 120 ± 60 pmol/l. When normalised to total particulate carbon, heme b was most abundant during the initiation of the nutrient replete spring bloom, when ratios reached 52 ± 24 µmol/mol; ten times higher than values observed both pre and post the primary bloom. Concentrations of heme b correlated with those of chlorophyll a. Nevertheless, differences were observed in the relative concentrations of the two parameters, with heme b concentrations increasing relative to chlorophyll a during the growth of the primary bloom, decreasing over the period of the secondary bloom and increasing again through the latter period of the experiment. Heme b abundance was therefore influenced by nutrient concentrations and also likely by changing community composition. In half of the mesocosms, pCO2 was elevated and maintained at ca.1000 µatm, however we observed no significant differences between heme b in plus or ambient pCO2 mesocosms, either in absolute terms, or relative to total particulate carbon and chlorophyll a. The results obtained in this study contribute to our understanding of the distribution of this significant component of the biogenic iron pool, and provide an iron replete coastal water end member that aids the interpretation of the distributions of heme b in more iron deplete open ocean waters.

Description: The file contains dissolved and total dissolvable trace metal concentrations (Fe, Co, Mn, Ni, Cd, Cu, Pb, Zn and V), hydrogen peroxide (H2O2), Fe(II), and iodide and iodate concentrations of surface water samples and station depth profiles. Trace metal concentrations were measured by ICP-MS after preconcentration (Rapp et al. 2017, Anal. Chim. Acta). Fe(II) and H2O2 were analyzed on-board using chemiluminescence flow injection analysis (Hopwood et al. 2017, Sci. Rep.). Iodide concentrations were analyzed by cathodic stripping square wave voltammetry (Luther et al. 1988, Anal. Chem.) and Iodate concentrations were measured spectrophotometrically (Chapman and Liss 1977, Mar. Chem.).

Description: The file contains dissolved and total dissolvable trace metal concentrations (Fe, Co, Mn, Ni, Cd, Cu, Pb, Zn and V), hydrogen peroxide (H2O2), Fe(II), and iodide and iodate concentrations of surface water samples and station depth profiles. Trace metal concentrations were measured by ICP-MS after preconcentration (Rapp et al. 2017, Anal. Chim. Acta). Fe(II) and H2O2 were analyzed on-board using chemiluminescence flow injection analysis (Hopwood et al. 2017, Sci. Rep.). Iodide concentrations were analyzed by cathodic stripping square wave voltammetry (Luther et al. 1988, Anal. Chem.) and Iodate concentrations were measured spectrophotometrically (Chapman and Liss 1977, Mar. Chem.).

Description: The file contains dissolved and total dissolvable trace metal concentrations (Fe, Co, Mn, Ni, Cd, Cu, Pb, Zn and V), hydrogen peroxide (H2O2), Fe(II), and iodide and iodate concentrations of surface water samples and station depth profiles. Trace metal concentrations were measured by ICP-MS after preconcentration (Rapp et al. 2017, Anal. Chim. Acta). Fe(II) and H2O2 were analyzed on-board using chemiluminescence flow injection analysis (Hopwood et al. 2017, Sci. Rep.). Iodide concentrations were analyzed by cathodic stripping square wave voltammetry (Luther et al. 1988, Anal. Chem.) and Iodate concentrations were measured spectrophotometrically (Chapman and Liss 1977, Mar. Chem.).

Description: The file contains dissolved and total dissolvable trace metal concentrations (Fe, Co, Mn, Ni, Cd, Cu, Pb, Zn and V), hydrogen peroxide (H2O2), Fe(II), and iodide and iodate concentrations of surface water samples and station depth profiles. Trace metal concentrations were measured by ICP-MS after preconcentration (Rapp et al. 2017, Anal. Chim. Acta). Fe(II) and H2O2 were analyzed on-board using chemiluminescence flow injection analysis (Hopwood et al. 2017, Sci. Rep.). Iodide concentrations were analyzed by cathodic stripping square wave voltammetry (Luther et al. 1988, Anal. Chem.) and Iodate concentrations were measured spectrophotometrically (Chapman and Liss 1977, Mar. Chem.).

Description: Surface ocean pH is declining due to anthropogenic atmospheric CO2 uptake with a global decline of ~0.3 possible by 2100. Extracellular pH influences a range of biological processes, including nutrient uptake, calcification and silicification. However, there are poor constraints on how pH levels in the extracellular microenvironment surrounding phytoplankton cells (the phycosphere) differ from bulk seawater. This adds uncertainty to biological impacts of environmental change. Furthermore, previous modelling work suggests that phycosphere pH of small cells is close to bulk seawater, and this has not been experimentally verified. Here we observe under 140 μmol photons/m**2/s the phycosphere pH of Chlamydomonas concordia (5 µm diameter), Emiliania huxleyi (5 µm), Coscinodiscus radiatus (50 µm) and C. wailesii (100 µm) are 0.11 ± 0.07, 0.20 ± 0.09, 0.41 ± 0.04 and 0.15 ± 0.20 (mean ± SD) higher than bulk seawater (pH 8.00), respectively. Thickness of the pH boundary layer of C. wailesii increases from 18 ± 4 to 122 ± 17 µm when bulk seawater pH decreases from 8.00 to 7.78. Phycosphere pH is regulated by photosynthesis and extracellular enzymatic transformation of bicarbonate, as well as being influenced by light intensity and seawater pH and buffering capacity. The pH change alters Fe speciation in the phycosphere, and hence Fe availability to phytoplankton is likely better predicted by the phycosphere, rather than bulk seawater. Overall, the precise quantification of chemical conditions in the phycosphere is crucial for assessing the sensitivity of marine phytoplankton to ongoing ocean acidification and Fe limitation in surface oceans.

Description: Sediment and pore water samples were collected during the M147 cruise of Research Vessel Meteor in April and May 2018. Additional sediment samples (GeoB 4417-5 and GeoB 4409-2) were collected during the M38-2 cruise in March 1997. Total element concentrations (Fe, Al, K) of the solid phase were measured after acid digestion (HF, HNO3 and HClO4) by inductively coupled plasma optical emission spectrometry (Varian ICP 720-ES). Solid phase iron speciation data were measured following single step sodium dithionite extraction (FeD) or sequential Fe extraction (FeAc, FeDith, FeOxal) by inductively coupled plasma optical emission spectrometry (Varian ICP 720-ES). Solid phase pyrite concentrations (FePy) were calculated stoichiometrically from photometrically measured S2- released via chromium(II) chloride reduction. Total organic carbon (TOC) of the sediment samples was measured in an Elemental Analyzer (Euro EA). Prior to analysis carbon bound to carbonate minerals was removed by leaching the sediment with 0.25 N HCl. Pore water nitrate concentrations were measured on board with a SEAL QuAAtro continuous flow auto analyzer. Pore water samples for dissolved element analysis were acidified with HCl to pH 〈 2 after sampling. Depending on the concentration range, pore water K and Fe was measured by inductively coupled plasma optical emission spectrometry (Varian 720 ES) or inductively coupled plasma mass spectrometry (Agilent 7500).

Description: Pore water nitrate concentrations were measured on board with a SEAL QuAAtro continuous flow auto analyzer. Pore water samples for dissolved element analysis were acidified with HCl to pH 〈 2 after sampling. Depending on the concentration range, pore water K and Fe was measured by inductively coupled plasma optical emission spectrometry (Varian 720 ES) or inductively coupled plasma mass spectrometry (Agilent 7500).

Description: Pore water nitrate concentrations were measured on board with a SEAL QuAAtro continuous flow auto analyzer. Pore water samples for dissolved element analysis were acidified with HCl to pH 〈 2 after sampling. Depending on the concentration range, pore water K and Fe was measured by inductively coupled plasma optical emission spectrometry (Varian 720 ES) or inductively coupled plasma mass spectrometry (Agilent 7500).

Description: Total element concentrations (Fe, Al, K) of the solid phase were measured after acid digestion (HF, HNO3 and HClO4) by inductively coupled plasma optical emission spectrometry (Varian ICP 720-ES). Solid phase iron speciation data were measured following single step sodium dithionite extraction (FeD) or sequential Fe extraction (FeAc, FeDith, FeOxal) by inductively coupled plasma optical emission spectrometry (Varian ICP 720-ES). Solid phase pyrite concentrations (FePy) were calculated stoichiometrically from photometrically measured S2- released via chromium(II) chloride reduction. Total organic carbon (TOC) of the sediment samples was measured in an Elemental Analyzer (Euro EA). Prior to analysis carbon bound to carbonate minerals was removed by leaching the sediment with 0.25 N HCl.