scholarly journals The role of iron species on the competition of two coastal diatoms, <i>Skeletonema costatum</i> and <i>Thalassosira weissflogii</i>

2013 ◽  
Vol 10 (12) ◽  
pp. 19603-19631 ◽  
Author(s):  
S.-X. Li ◽  
F.-J. Liu ◽  
F.-Y. Zheng ◽  
Y.-G. Zuo ◽  
X.-G. Huang
Keyword(s):  
Interspecific Competition ◽  
Cell Density ◽  
Skeletonema Costatum ◽  
Density Ratio ◽  
Iron Species ◽  
Colloidal Iron ◽  
Dissolved Iron ◽  
Fe Species ◽  
Particulate Iron ◽  
Algal Exudates

Abstract. Coastal diatoms are often exposed to macronutrient (N and P) and Fe enrichment. However, how these exposures influence on Fe biogeochemical cycle and then on diatom interspecific competition is unknown. In this study, two non-toxic coastal diatoms, Skeletonema costatum and Thalassosira weissflogii were exposed to N, P, and Fe enrichment for four-day. The growth of algae was co-controlled by macronutrient and Fe species (Fe (III)-EDTA, Fe(OH)3, dissolved, colloidal, and particulate Fe from culture medium). The influence of Fe species on algal cell density was more significant than macronutrient. When S. costatum coexisted with T. weissflogii, their cell density ratios were ranged between 5.57–7.03 times, indicating that S. costatum was more competitive than T. weissflogii. There were not significant correlation between cell density ratio and iron requirement, including iron adsorption and absorption per cell, iron adsorption and absorption by all algal cells. As Fe complexing ligands, algal exudates can promote diatom growth itself and such promotion on S. costatum was more obvious than that on T. weissflogii. Iron species was a key determinant on interspecific competition of coastal diatom, and the degree of bioavailability was described as follows: dissolved iron from own exudates > colloidal iron from own exudates > particulate iron from own exudates > particulate iron from another algal exudates > colloidal iron from another algal exudates > dissolved iron from another algal exudates > Fe (III)-EDTA> Fe (OH)3.

scholarly journals Iron stable isotopes track pelagic iron cycling during a subtropical phytoplankton bloom

2014 ◽  
Vol 112 (1) ◽  
pp. E15-E20 ◽  
Author(s):  
Michael J. Ellwood ◽  
David A. Hutchins ◽  
Maeve C. Lohan ◽  
Angela Milne ◽  
Philipp Nasemann ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Mixed Layer ◽  
Phytoplankton Bloom ◽  
Iron Bioavailability ◽  
Global Ocean ◽  
Minor Role ◽  
Surface Mixed Layer ◽  
Spring Phytoplankton Bloom ◽  
Dissolved Iron ◽  
Particulate Iron

The supply and bioavailability of dissolved iron sets the magnitude of surface productivity for ∼40% of the global ocean. The redox state, organic complexation, and phase (dissolved versus particulate) of iron are key determinants of iron bioavailability in the marine realm, although the mechanisms facilitating exchange between iron species (inorganic and organic) and phases are poorly constrained. Here we use the isotope fingerprint of dissolved and particulate iron to reveal distinct isotopic signatures for biological uptake of iron during a GEOTRACES process study focused on a temperate spring phytoplankton bloom in subtropical waters. At the onset of the bloom, dissolved iron within the mixed layer was isotopically light relative to particulate iron. The isotopically light dissolved iron pool likely results from the reduction of particulate iron via photochemical and (to a lesser extent) biologically mediated reduction processes. As the bloom develops, dissolved iron within the surface mixed layer becomes isotopically heavy, reflecting the dominance of biological processing of iron as it is removed from solution, while scavenging appears to play a minor role. As stable isotopes have shown for major elements like nitrogen, iron isotopes offer a new window into our understanding of the biogeochemical cycling of iron, thereby allowing us to disentangle a suite of concurrent biotic and abiotic transformations of this key biolimiting element.

scholarly journals Resupply of mesopelagic dissolved iron controlled by particulate iron composition

2019 ◽  
Vol 12 (12) ◽  
pp. 995-1000 ◽  
Author(s):  
M. Bressac ◽  
C. Guieu ◽  
M. J. Ellwood ◽  
A. Tagliabue ◽  
T. Wagener ◽  
...  
Keyword(s):  
Dissolved Iron ◽  
Iron Composition ◽  
Particulate Iron

Intensified-Fenton process for the treatment of phenol aqueous solutions

2014 ◽  
Vol 71 (3) ◽  
pp. 359-365 ◽  
Author(s):  
M. Isabel Pariente ◽  
Raúl Molina ◽  
Juan Antonio Melero ◽  
Juan Ángel Botas ◽  
Fernando Martínez
Keyword(s):  
Hydrogen Peroxide ◽  
Aqueous Solutions ◽  
Heterogeneous Catalyst ◽  
Reaction Temperature ◽  
Catalytic Performance ◽  
Fenton Process ◽  
Iron Species ◽  
Iron Extraction ◽  
Dissolved Iron ◽  
Iron Leaching

An intensified-Fenton process for the treatment of phenol aqueous solutions has been studied as a continuous catalytic wet hydrogen peroxide oxidation system. This process consists of coupling the catalytic activity of a heterogeneous Fenton-like catalyst with the homogeneous contribution of its dissolved iron species. Agglomerated mesoporous SBA-15 silica-supported iron oxide (Fe2O3/SBA-15) material was used as heterogeneous catalyst. The influence of the reaction temperature and the initial hydrogen peroxide dosages was studied in order to minimize the operation cost of the process. The catalytic performance of the process was assessed in terms of total organic carbon (TOC) and hydrogen peroxide conversions. Likewise, the stability of the solid Fenton-like catalyst was also evaluated in terms of the dissolved iron species. The increase of the reaction temperature enhanced the TOC conversion and reduced the iron leaching from the heterogeneous catalyst. These results were related to the degradation of oxalic acid as responsible for iron extraction by formation of soluble stable iron complexes into the aqueous medium. Finally, the use of a moderate hydrogen peroxide concentration (2.6 g/L) and milder temperatures (80–120 °C) has led to remarkable results of TOC and phenol reductions as well as oxidant efficiency through the intensified-Fenton process.

scholarly journals An iron budget during the natural iron fertilisation experiment KEOPS (Kerguelen Islands, Southern Ocean)

2009 ◽  
Vol 6 (4) ◽  
pp. 6803-6837 ◽  
Author(s):  
F. Chever ◽  
G. Sarthou ◽  
E. Bucciarelli ◽  
S. Blain ◽  
A. R. Bowie
Keyword(s):  
Southern Ocean ◽  
Dissolved Iron ◽  
Heard Island ◽  
Natural Iron ◽  
Particulate Iron ◽  
The Difference ◽  
The One ◽  
Iron Pool ◽  
Lateral Advection ◽  
Very High

Abstract. Total dissolvable iron (TDFe) was measured in the water column above and in the surrounding of the Kerguelen Plateau (Indian sector of the Southern Ocean) during the KErguelen Ocean Plateau compared Study (KEOPS) cruise. TDFe concentrations ranged from 0.90 to 65.6 nmol L−1 above the plateau and from 0.34 to 2.23 nmol L−1 offshore of the plateau. Station C1 located south of the plateau, near Heard Island, exhibited very high values (329–770 nmol L−1). Apparent particulate iron (Feapp), calculated as the difference between the TDFe and the dissolved iron measured on board (DFe) represented 95±5% of the TDFe above the plateau, suggesting that particles and refractory colloids largely dominated the iron pool. This paper presents a budget of DFe and Feapp above the plateau. Lateral advection of water that had been in contact with the continental shelf of Heard Island seems to be the predominant source of Feapp and DFe above the plateau, with a supply of 9.7±2.3×106 and 8.3±6.7×103 mol d−1, respectively. The residence times of 1.7 and 48 days estimated for Feapp and DFe, respectively, indicate a rapid turnover in the surface water. A comparison between Feapp and total particulate iron (TPFe) suggests that the total dissolved fraction is mainly constituted of small refractory colloids. This fraction does not seem to be a potential source of iron to the phytoplankton in our study. Finally, when taking into account the lateral supply of dissolved iron, the seasonal carbon sequestration efficiency was estimated at 154 000 mol C (mol Fe)−1, which is 4-fold lower than the previously estimated value in this area but still 18-fold higher than the one estimated during the other study of a natural iron fertilisation experiment, CROZEX.

A Methodology for Quantifying Cell Density and Distribution in Multidimensional Bioprinted Gelatin-Alginate Constructs

2017 ◽  
Author(s):  
Houzhu Ding ◽  
Enyan Dai ◽  
Filippos Tourlomousis ◽  
Robert C. Chang
Keyword(s):  
Cell Density ◽  
Time Course ◽  
Density Ratio ◽  
Time Dependent ◽  
Control Group ◽  
3D Analysis ◽  
Cell Distribution ◽  
The Cross ◽  
Time Course Study ◽  
Cell Densities

Bioprinted tissue constructs are enabled by microextrusion-based co-printing of cells and hydrogel materials. In this paper, a gelatin-alginate hydrogel material formulation is implemented as the bio-ink towards a 3D cell-laden tissue construct. However, of fundamental importance during the printing process is the interplay between the various parameters that yield the final cell distribution and cell density at different dimensional scales. To investigate these effects, this study advances a multidimensional analytical framework to determine the spatial variations and temporal evolution of cell distribution and cell density within a bioprinted cell-laden construct. In the one dimensional (1D) analysis, the cell distribution and cross-sectional shape for a single printed fiber are observed to be dependent on the process temperature and material concentration parameters. This is illustrated by the reliable fabrication and image line profile analysis of the fiber prints. Round fiber prints with a measured width of 809.5±52.3 μm maintain dispersive cells with a degree of dispersion (Dd) at 96.8 % that can be achieved at high relative material viscosities under low temperature conditions (21 °C) or high material concentrations (10 % w/v gelatin). On the other hand, flat fiber prints with a measured width of 1102.2±63.6 μm coalesce cells towards the fiber midline with Dd = 76.3% that can be fabricated at low relative material viscosities under high temperature (24 °C) or low material concentrations (7.5 % w/v gelatin). In the 2D analysis, a printed grid structure yields differential cell distribution whereby differences in localized cell densities are observed between the strut and cross regions within the printed structure. At low relative viscosities, cells aggregate at the cross regions where two overlapping filaments fuse together, yielding a cell density ratio of 2.06±0.44 between the cross region and strut region. However, at high relative viscosities, the cell density ratio decreases to 0.96±0.03. In the 3D analysis, the cell density attributed to the different layers is studied as a function of printing time elapsed from the initial bio-ink formulation. Due to identifiable gravity and extrusion process-induced effects, the cell distribution within the original bio-ink cartridge or material reservoir is altered over time to yield initial quantitative increases in the cell density over the first several printed layers, followed by quantitative decreases in the subsequent printed layers. Finally, in the time-dependent analysis, the evolution of cell density and the emergence of material degradation effects is studied over a time course study. Variable initial cell densities (0.6 × 106 cells/ml, 1.0 × 106 cells/ml, and acellular control group) printed and cross-linked into cell-laden constructs for the 48 hr time course study exhibit a time-dependent increase in cell density owing to proliferation within the constructs that are presumed to accelerate the degradation rate.

Pola Pertumbuhan, Biomassa Dan Kandungan Protein Kasar Kultur Skeletonema costatum Skala Massal Dengan Konsentrasi Kalium Nitrat Berbeda

2018 ◽  
Vol 7 (2) ◽  
pp. 75
Author(s):  
Diyah Putri Ambarwati ◽  
Ervia Yudiati ◽  
Endang Supriyantini ◽  
Lilik Maslukah
Keyword(s):  
Stationary Phase ◽  
Protein Content ◽  
Cell Density ◽  
Growth Pattern ◽  
Crude Protein ◽  
Culture Media ◽  
Skeletonema Costatum ◽  
Potassium Nitrate ◽  
Mass Scale ◽  
Crude Protein Content

Mikroalga Skeletonema costatum merupakan pakan alami yang mengandung nutrisi yang diperlukan untuk budidaya perikanan. Modifikasi media kultur merupakan salah satu upaya optimalisasi produktivitas sekaligus meningkatkan kadar proteinnya. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian KNO3 dengan berbagai konsentrasi terhadap pola pertumbuhan, biomassa dan kandungan protein kasar. Metode penelitian yang digunakan adalah metode eksperimen Rancangan Acak Lengkap, dengan lima konsentrasi KNO3 (A: 25; B:50; C:75; D:100 dan E:125 ppm) yang diulang sebanyak tiga kali. Inokulum awal adalah satu ton,103 sel/mL. Saat mencapai fase stasioner, kultur massal S. costatum dipanen dan dikeringkan. Kandungan protein kasar dianalisis menggunakan metode Kjeldahl. Hasil penelitian terhadap kepadatan menunjukkan bahwa perlakuan terbaik dicapai pada konsentrasi KNO3 125 ppm (498,88. 103 sel/mL) diikuti D (316,94. 10³ sel/mL), C (313,81.10³ sel/mL), B (246,56. 10³ sel/mL) dan A (195,60. 10³ sel/mL). Terdapat perbedaan fase stasioner pada masing-masing perlakuan yaitu A:32; B:28; C: 37; D:32; E:36 jam. Biomass rata-rata yang dihasilkan pada tiap perlakuan sesuai dengan pola kepadatan sel yaitu E: 8,60, D:7,85, C:6,43, B:5,91 dan A:5,44 g. Analisa terhadap kandungan protein kasar menunjukkan tidak adanya perbedaan antar perlakuan (P>0,05). Pemberian KNO3 terbukti dapat meningkatkan kepadatan sel dan berpengaruh terhadap pola pertumbuhan dan biomassa, namun kandungan protein kasar tidak meningkat. Growth, Biomass and Rough Protein Content of Skeletonema costatum Mass Scale with Different Concentration of Potassium Nitrate (KNO3) Skeletonema costatum is natural microalgae which rich in nutrient. An effort to optimize the protein content was done by modifying the culture media. This research is aimed to find out the effect of various concentration of KNO3 addition to the growth pattern, biomass and crude protein content. The Completely Randomized Design with five treatment KNO3 (A: 25; B:50; C:75; D:100 dan E:125 ppm) in three replication were applied. The starting innoculum was one tonne, 103 cel/mL. The microalgae was harvested at stationary phase and the dried. The crude protein was analised by Kjeldahl methods. The results of cell density showed that the best concentration was E (498,88. 103 cells/mL), D (316,94. 10³ cells/mL), C (313,81.10³ cells/mL), B (246,56. 10³ cells/mL) and A (195,60. 10³ cells/mL) respectively. The stationary phase in every treatment was reached at different time A:32; B:28; C: 37; D:32; E:36 hr. The average biomass were at similar pattern to the cell density (E:8,60, D:7,85, C:6,43, B:5,91 and A:5,44 g). On the other hand, the crude protein content were not significantly different (P>0,05). It is concluded that the KNO3 addition enhanced the cell density, growth pattern, biomass. The protein content was remain similar. 

scholarly journals Temporal variability of dissolved iron species in the mesopelagic zone at Ocean Station PAPA

2017 ◽  
Vol 172 ◽  
pp. 128-136 ◽  
Author(s):  
Christina Schallenberg ◽  
Andrew R.S. Ross ◽  
Ashley B. Davidson ◽  
Gillian M. Stewart ◽  
Jay T. Cullen
Keyword(s):  
Temporal Variability ◽  
Iron Species ◽  
Dissolved Iron ◽  
Mesopelagic Zone ◽  
Ocean Station Papa
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