scholarly journals Senescence as the main driver of iodide release from a diverse range of marine phytoplankton

2020 ◽  
Vol 17 (9) ◽  
pp. 2453-2471 ◽  
Author(s):  
Helmke Hepach ◽  
Claire Hughes ◽  
Karen Hogg ◽  
Susannah Collings ◽  
Rosie Chance
Keyword(s):  
Sea Surface ◽  
Marine Phytoplankton ◽  
Phase Cell ◽  
Diverse Range ◽  
Biogeochemical Models ◽  
Cell Mortality ◽  
Significant Difference ◽  
Main Driver ◽  
Inorganic Iodine ◽  
Iodine Release

Abstract. The reaction between ozone and iodide at the sea surface is now known to be an important part of atmospheric ozone cycling, causing ozone deposition and the release of ozone-depleting reactive iodine to the atmosphere. The importance of this reaction is reflected by its inclusion in chemical transport models (CTMs). Such models depend on accurate sea surface iodide fields, but measurements are spatially and temporally limited. Hence, the ability to predict current and future sea surface iodide fields, i.e. sea surface iodide concentration on a narrow global grid, requires the development of process-based models. These models require a thorough understanding of the key processes that control sea surface iodide. The aim of this study was to explore if there are common features of iodate-to-iodide reduction amongst diverse marine phytoplankton in order to develop models that focus on sea surface iodine and iodine release to the troposphere. In order to achieve this, rates and patterns of changes in inorganic iodine speciation were determined in 10 phytoplankton cultures grown at ambient iodate concentrations. Where possible these data were analysed alongside results from previous studies. Iodate loss and some iodide production were observed in all cultures studied, confirming that this is a widespread feature amongst marine phytoplankton. We found no significant difference in log-phase, cell-normalised iodide production rates between key phytoplankton groups (diatoms, prymnesiophytes including coccolithophores and phaeocystales), suggesting that a phytoplankton functional type (PFT) approach would not be appropriate for building an ocean iodine cycling model. Iodate loss was greater than iodide formation in the majority of the cultures studied, indicating the presence of an as-yet-unidentified “missing iodine” fraction. Iodide yield at the end of the experiment was significantly greater in cultures that had reached a later senescence stage. This suggests that models should incorporate a lag between peak phytoplankton biomass and maximum iodide production and that cell mortality terms in biogeochemical models could be used to parameterise iodide production.

scholarly journals Common features of iodate to iodide reduction amongst a diverse range of marine phytoplankton

2019 ◽  
Author(s):  
Helmke Hepach ◽  
Claire Hughes ◽  
Karen Hogg ◽  
Susannah Collings ◽  
Rosie Chance
Keyword(s):  
Sea Surface ◽  
Marine Phytoplankton ◽  
Phase Cell ◽  
Transport Models ◽  
Diverse Range ◽  
Common Features ◽  
Biogeochemical Models ◽  
Cell Mortality ◽  
Significant Difference ◽  
Inorganic Iodine

Abstract. The reaction between ozone and iodide at the sea surface is now known to be an important part of atmospheric ozone cycling, causing ozone deposition and the release of ozone-depleting reactive iodine to the atmosphere. The importance of this reaction is reflected by its inclusion in chemical transport models (CTMs). Such models depend on accurate sea surface iodide fields but measurements are spatially and temporally limited. The ability to predict current and future sea surface iodide fields requires the development of process-based models which in turn require a thorough understanding of the key processes controlling inorganic iodine cycling. The aim of this study was to inform the development of ocean iodine cycling models by exploring if there are common features of iodate to iodide reduction amongst diverse marine phytoplankton. In order to achieve this, rates and patterns of changes in inorganic iodine speciation were determined in 10 phytoplankton cultures grown at ambient iodate concentrations. Where possible these data were analysed alongside results from previous studies. Iodate loss and some iodide production was observed in all cultures studied, confirming that this is a widespread feature amongst marine phytoplankton. We found no significant difference in log-phase, cell-normalised iodide production rates between key phytoplankton groups (diatoms, prymesiophytes including coccolithophores and phaeocystales) suggesting that a Phytoplankton Functional Type (PFT) approach would not be appropriate for building an ocean iodine cycling model. Iodate loss was greater than iodide formation in the majority of the cultures studied, indicating the presence of an as yet unidentified missing iodine fraction. Iodide yield at the end of the experiment was significantly greater in cultures that had reached a later senescence stage. This suggests that models should incorporate a lag between peak phytoplankton biomass and maximum iodide production, and that cell mortality terms in biogeochemical models could be used to parameterize iodide production.

scholarly journals New insights into aerosol and climate in the Arctic

2018 ◽  
Author(s):  
Jonathan P. D. Abbatt ◽  
W. Richard Leaitch ◽  
Amir A. Aliabadi ◽  
Alan K. Bertram ◽  
Jean-Pierre Blanchet ◽  
...  
Keyword(s):  
Long Range ◽  
Mineral Dust ◽  
Sea Surface ◽  
The Arctic ◽  
Long Range Transport ◽  
Surface Microlayer ◽  
Biogeochemical Models ◽  
Sea Surface Microlayer ◽  
Range Transport ◽  
Warming World

Abstract. Motivated by the need to predict how the Arctic atmosphere will change in a warming world, this article summarizes recent advances made by the research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) that contribute to our fundamental understanding of Arctic aerosol particles as they relate to climate forcing. The overall goal of NETCARE research has been to use an interdisciplinary approach encompassing extensive field observations and a range of chemical transport, earth system, and biogeochemical models. Several major findings and advances have emerged from NETCARE since its formation in 2013 . (1) Unexpectedly high summertime dimethyl sulfide (DMS) levels were identified in ocean water and the overlying atmosphere in the Canadian Arctic Archipelago (CAA). Furthermore, melt ponds, which are widely prevalent, were identified as an important DMS source. (2) Evidence was found of widespread particle nucleation and growth in the marine boundary layer in the CAA in the summertime. DMS-oxidation-driven nucleation is facilitated by the presence of atmospheric ammonia arising from sea bird colony emissions, and potentially also from coastal regions, tundra, and biomass burning. Via accumulation of secondary organic material (SOA), a significant fraction of the new particles grow to sizes that are active in cloud droplet formation. Although the gaseous precursors to Arctic marine SOA remain poorly defined, the measured levels of common continental SOA precursors (isoprene and monoterpenes) were low, whereas elevated mixing ratios of oxygenated volatile organic compounds were inferred to arise via processes involving the sea surface microlayer. (3) The variability in the vertical distribution of black carbon (BC) under both springtime Arctic haze and more pristine summertime aerosol conditions was observed. Measured particle size distributions and mixing states were used to constrain, for the first time, calculations of aerosol–climate interactions under Arctic conditions. Aircraft- and ground-based measurements were used to better establish the BC source regions that supply the Arctic via long-range transport mechanisms. (4) Measurements of ice nucleating particles (INPs) in the Arctic indicate that a major source of these particles is mineral dust, likely derived from local sources in the summer and long-range transport in the spring. In addition, INPs are abundant in the sea surface microlayer in the Arctic, and possibly play a role in ice nucleation in the atmosphere when mineral dust concentrations are low. (5) Amongst multiple aerosol components, BC was observed to have the smallest effective deposition velocities to high Arctic snow.

Electrospun regenerated silk fibroin is a promising biomaterial for the maintenance of inner ear progenitors in vitro

2021 ◽  
pp. 088532822110515
Author(s):  
Guangfei Li ◽  
Yanbo Yin ◽  
Yaopeng Zhang ◽  
Jingfang Wu ◽  
Shan Sun
Keyword(s):  
Inner Ear ◽  
Silk Fibroin ◽  
Hair Cells ◽  
Engineering Research ◽  
Cell Mortality ◽  
Regenerated Silk Fibroin ◽  
Significant Difference ◽  
Student’S T ◽  
New Strategies

Objective We sought to determine the biocompatibility of electrospun regenerated silk fibroin (RSF) mats with inner ear progenitors, especially their effect on the differentiation of inner ear progenitors into hair cells. Methods Neonatal mouse cochleae (n = 20) were collected and digested and allowed to form spheres over several days. Cells digested from the spheres were then seeded onto aligned or random RSF mats, with laminin-coated coverslips serving as controls. The inner ear progenitor cell mortality was examined by TUNEL labeling, and the adhesion of cells to the RSF mats or coverslip was determined by scanning electron microscopy. Finally, the number of hair cells that differentiated from inner ear progenitors was determined by Myosin7a expression. Unpaired Student’s t-tests and one-way ANOVA followed by a Dunnett’s multiple comparisons test were used in this study ( p < 0.05). Results After 5 days of culture, the inner ear progenitors had good adhesion to both the aligned and random RSF mats and there was no significant difference in TUNEL+ cells between the mats compared to the coverslip ( p > 0.05). After 7 days of in vitro differentiation culture, the percentage of differentiated hair cells on the control, aligned, and random RSF mats was 2.5 ± 0.5%, 2.7 ± 0.4%, and 2.4 ± 0.2%, respectively, and there was no significant difference between Myosin7a+ cells on either RSF mat compared to controls ( p > 0.05). Conclusion The aligned and random RSF mats had excellent biocompatibility with inner ear progenitors and helped the inner ear progenitors maintain their stemness. Our results thus indicate that RSF mats represent a useful scaffold for the development of new strategies for inner ear tissue engineering research.

scholarly journals P016: Junior and senior clinician educators rank key medical education articles differently depending on topic

CJEM ◽  
2018 ◽  
Vol 20 (S1) ◽  
pp. S62-S62
Author(s):  
K. Lam ◽  
T.M. Chan ◽  
M. Gottlieb ◽  
S. Shamshoon
Keyword(s):  
Medical Education ◽  
Multilevel Regression ◽  
Diverse Range ◽  
Clinical Educators ◽  
Clinician Educators ◽  
Building Process ◽  
Senior Clinician ◽  
Significant Difference ◽  
Significant Divergence ◽  
Selection Of

Introduction: Medical education includes a diverse range of topics and disciplines. For junior clinician educators, it may be difficult to get a grasp of pertinent literature. Our study aims to retrospectively identify whether senior clinician educators (SCEs) and junior clinician educators (JCEs) differ in their selection of what they perceive as key medical education articles. Methods: As a part of the Academic Life in Emergency Medicine (ALiEM) Faculty Incubator program, we developed a series of primer articles for JCEs over the preceding year, designed to enhance their educational growth by identifying and discussing key articles within specific medical education arenas. Each set of articles within the primer series were selected based on data collected from JCEs and SCEs, who ranked the specific articles with respect to their perceived relevancy to the JCEs. ANOVA analysis was performed for each of the nine primer series to determine whether there was a statistically significant difference between senior and junior CEs ratings of articles. Results: 216 total articles were evaluated within the nine different primer topics. Through a multilevel regression analysis of the data, no statistically significant difference was found between the rankings of papers by SCEs and JCEs (95%CI: -0.27, 0.40). However, a subgroup analysis of the data found that 3 of the 9 primers showed statistically significant divergence based on seniority (p<0.05). Conclusion: Based on this data, involvement of JCEs in the consensus-building process was important in identifying divergence in views between JCEs and SCEs in one-third of cases. To our knowledge, no other group have compared whether junior and senior clinical educators may have divergent opinions about the relevance of medical education literature. Our findings suggest that it may be important to involve JCEs in selecting articles that are worthwhile for their learning, since SCEs may not fully understand their needs.

scholarly journals Overview paper: New insights into aerosol and climate in the Arctic

2019 ◽  
Vol 19 (4) ◽  
pp. 2527-2560 ◽  
Author(s):  
Jonathan P. D. Abbatt ◽  
W. Richard Leaitch ◽  
Amir A. Aliabadi ◽  
Allan K. Bertram ◽  
Jean-Pierre Blanchet ◽  
...  
Keyword(s):  
Long Range ◽  
Mineral Dust ◽  
Sea Surface ◽  
The Arctic ◽  
Long Range Transport ◽  
Surface Microlayer ◽  
Biogeochemical Models ◽  
Sea Surface Microlayer ◽  
Range Transport ◽  
Warming World

Abstract. Motivated by the need to predict how the Arctic atmosphere will change in a warming world, this article summarizes recent advances made by the research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) that contribute to our fundamental understanding of Arctic aerosol particles as they relate to climate forcing. The overall goal of NETCARE research has been to use an interdisciplinary approach encompassing extensive field observations and a range of chemical transport, earth system, and biogeochemical models. Several major findings and advances have emerged from NETCARE since its formation in 2013. (1) Unexpectedly high summertime dimethyl sulfide (DMS) levels were identified in ocean water (up to 75 nM) and the overlying atmosphere (up to 1 ppbv) in the Canadian Arctic Archipelago (CAA). Furthermore, melt ponds, which are widely prevalent, were identified as an important DMS source (with DMS concentrations of up to 6 nM and a potential contribution to atmospheric DMS of 20 % in the study area). (2) Evidence of widespread particle nucleation and growth in the marine boundary layer was found in the CAA in the summertime, with these events observed on 41 % of days in a 2016 cruise. As well, at Alert, Nunavut, particles that are newly formed and grown under conditions of minimal anthropogenic influence during the months of July and August are estimated to contribute 20 % to 80 % of the 30–50 nm particle number density. DMS-oxidation-driven nucleation is facilitated by the presence of atmospheric ammonia arising from seabird-colony emissions, and potentially also from coastal regions, tundra, and biomass burning. Via accumulation of secondary organic aerosol (SOA), a significant fraction of the new particles grow to sizes that are active in cloud droplet formation. Although the gaseous precursors to Arctic marine SOA remain poorly defined, the measured levels of common continental SOA precursors (isoprene and monoterpenes) were low, whereas elevated mixing ratios of oxygenated volatile organic compounds (OVOCs) were inferred to arise via processes involving the sea surface microlayer. (3) The variability in the vertical distribution of black carbon (BC) under both springtime Arctic haze and more pristine summertime aerosol conditions was observed. Measured particle size distributions and mixing states were used to constrain, for the first time, calculations of aerosol–climate interactions under Arctic conditions. Aircraft- and ground-based measurements were used to better establish the BC source regions that supply the Arctic via long-range transport mechanisms, with evidence for a dominant springtime contribution from eastern and southern Asia to the middle troposphere, and a major contribution from northern Asia to the surface. (4) Measurements of ice nucleating particles (INPs) in the Arctic indicate that a major source of these particles is mineral dust, likely derived from local sources in the summer and long-range transport in the spring. In addition, INPs are abundant in the sea surface microlayer in the Arctic, and possibly play a role in ice nucleation in the atmosphere when mineral dust concentrations are low. (5) Amongst multiple aerosol components, BC was observed to have the smallest effective deposition velocities to high Arctic snow (0.03 cm s−1).

Relationship between spectral reflected irradiance at the sea surface and optical properties of marine phytoplankton

1994 ◽  
Author(s):  
Bogdan Wozniak ◽  
Witold von Smekot-Wensierksi ◽  
Roland Doerffer ◽  
Hartmut Grassl
Keyword(s):  
Optical Properties ◽  
Sea Surface ◽  
Marine Phytoplankton

scholarly journals Restructuring of genomic provinces of surface ocean plankton under climate change

2020 ◽  
Author(s):  
Paul Frémont ◽  
Marion Gehlen ◽  
Mathieu Vrac ◽  
Jade Leconte ◽  
Patrick Wincker ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Surface ◽  
Niche Theory ◽  
Surface Ocean ◽  
Warming Scenario ◽  
Scale Modeling ◽  
Scientific Issue ◽  
Physico Chemical ◽  
Main Driver ◽  
The Impact

AbstractThe impact of climate change on diversity, functioning and biogeography of marine plankton is a major unresolved scientific issue. Here, niche theory is applied on plankton metagenomes sampled during the Tara Oceans expedition to derive pan-ocean geographical structuring in climato-genomic provinces characterized by signature genomes for 6 size fractions, from viruses to meso-zooplankton. Assuming a high warming scenario (RCP8.5), the identified tropical provinces would expand and temperate provinces would shrink. Poleward shifts are projected for 96% of provinces in five major basins leading to their reorganization over ~50% of the surface ocean south of 60°N, of which 3% correspond to novel assemblages of provinces. Sea surface temperature is identified as the main driver and accounts only for ~51 % of the changes followed by phosphate (11%) and salinity (10.3%). These results demonstrate the potential of integration of genomics with physico-chemical data for higher scale modeling and understanding of ocean ecosystems.

scholarly journals Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models

2013 ◽  
Vol 10 (2) ◽  
pp. 3627-3676 ◽  
Author(s):  
L. Bopp ◽  
L. Resplandy ◽  
J. C. Orr ◽  
S. C. Doney ◽  
J. P. Dunne ◽  
...  
Keyword(s):  
21St Century ◽  
Primary Productivity ◽  
Multiple Stressors ◽  
Sea Surface ◽  
Marine Phytoplankton ◽  
Global Ocean ◽  
Cmip5 Models ◽  
Regional Patterns ◽  
Ocean Ecosystems ◽  
The Tropics

Abstract. Ocean ecosystems are increasingly stressed by human-induced changes of their physical, chemical and biological environment. Among these changes, warming, acidification, deoxygenation and changes in primary productivity by marine phytoplankton can be considered as four of the major stressors of open ocean ecosystems. Due to rising atmospheric CO2 in the coming decades, these changes will be amplified. Here, we use the most recent simulations performed in the framework of the Coupled Model Intercomparison Project 5 to assess how these stressors may evolve over the course of the 21st century. The 10 Earth System Models used here project similar trends in ocean warming, acidification, deoxygenation and reduced primary productivity for each of the IPCC's representative concentration parthways (RCP) over the 21st century. For the "business-as-usual" scenario RCP8.5, the model-mean changes in 2090s (compared to 1990s) for sea surface temperature, sea surface pH, global O2 content and integrated primary productivity amount to +2.73 °C, −0.33 pH unit, −3.45% and −8.6%, respectively. For the high mitigation scenario RCP2.6, corresponding changes are +0.71 °C, −0.07 pH unit, −1.81% and −2.0% respectively, illustrating the effectiveness of extreme mitigation strategies. Although these stressors operate globally, they display distinct regional patterns. Large decreases in O2 and in pH are simulated in global ocean intermediate and mode waters, whereas large reductions in primary production are simulated in the tropics and in the North Atlantic. Although temperature and pH projections are robust across models, the same does not hold for projections of sub-surface O2 concentrations in the tropics and global and regional changes in net primary productivity.

scholarly journals Evolution of primary production and its drivers on the Lebanese coast between 1986 and 2013

2020 ◽  
Vol 20 (4) ◽  
pp. 207-217
Author(s):  
Ali Fadel ◽  
Lama Salameh ◽  
Malak Kanj ◽  
Ahmad Kobaissi
Keyword(s):  
Primary Production ◽  
Phytoplankton Community ◽  
Controlling Factors ◽  
Sea Surface ◽  
Biogeochemical Model ◽  
Average Temperature ◽  
Biogeochemical Models ◽  
Increasing Trend ◽  
Production Dynamics ◽  
Lebanese Coast

AbstractPhysical-biogeochemical models help us to understand the dynamics and the controlling factors of primary production. In this study, the outputs of a validated hydrodynamic and biogeochemical model were used to elucidate the primary production dynamics between 1992 and 2012 for three studied sites on the Lebanese coast: Naqoura, Beirut, and Tripoli. The results showed that primary production presents a homogeneous spatial distribution along the Lebanese coastline. The phytoplankton community has a low optimal temperature. The thermocline develops in March, with maximum stratification in August and fades in October. Chlorophyll, dissolved oxygen and salinity were positively correlated throughout the water column. A significant increasing trend of sea surface temperature was found on the Lebanese coast over 27 years, between 1986 and 2013. Annual averages increased from 22°C in 1986 to 23.1°C in 2013 with the highest recorded average temperature of 23.7 °C in 2010.

scholarly journals A laboratory characterisation of inorganic iodine emissions from the sea surface: dependence on oceanic variables and parameterisation for global modelling

2013 ◽  
Vol 13 (12) ◽  
pp. 31445-31477 ◽  
Author(s):  
S. M. MacDonald ◽  
J. C. Gómez Martín ◽  
R. Chance ◽  
S. Warriner ◽  
A. Saiz-Lopez ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Chemistry ◽  
Marine Boundary Layer ◽  
Environmental Parameters ◽  
Sea Surface ◽  
Total Iodine ◽  
Iodide Ions ◽  
Iodine Compounds ◽  
Halogen Chemistry ◽  
Inorganic Iodine

Abstract. Reactive iodine compounds play a~significant role in the atmospheric chemistry of the oceanic boundary layer by influencing the oxidising capacity through catalytically removing O3 and altering the HOx and NOx balance. The sea-to-air flux of iodine over the open ocean is therefore an important quantity in assessing these impacts on a global scale. This paper examines the effect of a number of relevant environmental parameters, including water temperature, salinity and organic compounds, on the magnitude of the HOI and I2 fluxes produced from the uptake of O3 and its reaction with iodide ions in aqueous solution. The results of these laboratory experiments and those reported previously (Carpenter et al., 2013), along with sea surface iodide concentrations measured or inferred from measurements of dissolved total iodine and iodate reported in the literature, were then used to produce parameterised expressions for the HOI and I2 fluxes as a function of wind speed, sea-surface temperature and O3. These expressions were used in the Tropospheric HAlogen chemistry MOdel (THAMO) to compare with MAX-DOAS measurements of iodine monoxide (IO) performed during the HaloCAST-P cruise in the Eastern Pacific ocean (Mahajan et al., 2012). The modelled IO agrees reasonably with the field observations, although significant discrepancies are found during a period of low wind speeds (<3 m s−1), when the model overpredicts IO by up to a factor of three. The inorganic iodine flux contributions to IO are found to be comparable to, or even greater than, the contribution of organo-iodine compounds and therefore its inclusion in atmospheric models is important to improve predictions of the influence of halogen chemistry in the marine boundary layer.

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