scholarly journals Sediment carbon sink in low-density temperate eelgrass meadows (Baltic Sea)

2016 ◽  
Vol 121 (12) ◽  
pp. 2918-2934 ◽  
Author(s):  
Emilia Jankowska ◽  
Loïc N. Michel ◽  
Agata Zaborska ◽  
Maria Włodarska-Kowalczuk
Keyword(s):  
Baltic Sea ◽  
Carbon Sink ◽  
Low Density ◽  
Sediment Carbon

scholarly journals Mangrove carbon sink. Do burrowing crabs contribute to sediment carbon storage? Evidence from a Kenyan mangrove system

2014 ◽  
Vol 85 ◽  
pp. 524-533 ◽  
Author(s):  
Anna Andreetta ◽  
Marco Fusi ◽  
Irene Cameldi ◽  
Filippo Cimò ◽  
Stefano Carnicelli ◽  
...  
Keyword(s):  
Carbon Storage ◽  
Carbon Sink ◽  
Mangrove System ◽  
Sediment Carbon

scholarly journals Microbial Organic Matter Degradation Potential in Baltic Sea Sediments Is Influenced by Depositional Conditions andIn SituGeochemistry

2018 ◽  
Vol 85 (4) ◽  
Author(s):  
Laura A. Zinke ◽  
Clemens Glombitza ◽  
Jordan T. Bird ◽  
Hans Røy ◽  
Bo Barker Jørgensen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Microbial Communities ◽  
Carbon Cycling ◽  
Marine Sediments ◽  
Abiotic Factors ◽  
Organic Matter Degradation ◽  
Sediment Types ◽  
Polymer Hydrolysis ◽  
Sediment Carbon

ABSTRACTGlobally, marine sediments are a vast repository of organic matter, which is degraded through various microbial pathways, including polymer hydrolysis and monomer fermentation. The sources, abundances, and quality (i.e., labile or recalcitrant) of the organic matter and the composition of the microbial assemblages vary between sediments. Here, we examine new and previously published sediment metagenomes from the Baltic Sea and the nearby Kattegat region to determine connections between geochemistry and the community potential to degrade organic carbon. Diverse organic matter hydrolysis encoding genes were present in sediments between 0.25 and 67 meters below seafloor and were in higher relative abundances in those sediments that contained more organic matter. New analysis of previously published metatranscriptomes demonstrated that many of these genes were transcribed in two organic-rich Holocene sediments. Some of the variation in deduced pathways in the metagenomes correlated with carbon content and depositional conditions. Fermentation-related genes were found in all samples and encoded multiple fermentation pathways. Notably, genes involved in alcohol metabolism were amongst the most abundant of these genes, indicating that this is an important but underappreciated aspect of sediment carbon cycling. This study is a step towards a more complete understanding of microbial food webs and the impacts of depositional facies on present sedimentary microbial communities.IMPORTANCESediments sequester organic matter over geologic time scales and impact global climate regulation. Microbial communities in marine sediments drive organic matter degradation, but the factors controlling their assemblages and activities, which in turn impact their role in organic matter degradation, are not well understood. Hence, determining the role of microbial communities in carbon cycling in various sediment types is necessary for predicting future sediment carbon cycling. We examined microbial communities in Baltic Sea sediments, which were deposited across various climatic and geographical regimes to determine the relationship between microbial potential for breakdown of organic matter and abiotic factors, including geochemistry and sediment lithology. The findings from this study will contribute to our understanding of carbon cycling in the deep biosphere and how microbial communities live in deeply buried environments.

scholarly journals Blue carbon stocks in Baltic Sea eelgrass (<i>Zostera marina</i>) meadows

2016 ◽  
Vol 13 (22) ◽  
pp. 6139-6153 ◽  
Author(s):  
Maria Emilia Röhr ◽  
Christoffer Boström ◽  
Paula Canal-Vergés ◽  
Marianne Holmer
Keyword(s):  
Baltic Sea ◽  
Carbon Storage ◽  
Zostera Marina ◽  
Carbon Sink ◽  
Carbon Stocks ◽  
Blue Carbon ◽  
Carbon Accumulation ◽  
Sediment Surface ◽  
Dry Density ◽  
Sink Capacity

Abstract. Although seagrasses cover only a minor fraction of the ocean seafloor, their carbon sink capacity accounts for nearly one-fifth of the total oceanic carbon burial and thus play a critical structural and functional role in many coastal ecosystems. We sampled 10 eelgrass (Zostera marina) meadows in Finland and 10 in Denmark to explore seagrass carbon stocks (Corg stock) and carbon accumulation rates (Corg accumulation) in the Baltic Sea area. The study sites represent a gradient from sheltered to exposed locations in both regions to reflect expected minimum and maximum stocks and accumulation. The Corg stock integrated over the top 25 cm of the sediment averaged 627 g C m−2 in Finland, while in Denmark the average Corg stock was over 6 times higher (4324 g C m−2). A conservative estimate of the total organic carbon pool in the regions ranged between 6.98 and 44.9 t C ha−1. Our results suggest that the Finnish eelgrass meadows are minor carbon sinks compared to the Danish meadows, and that majority of the Corg produced in the Finnish meadows is exported. Our analysis further showed that > 40 % of the variation in the Corg stocks was explained by sediment characteristics, i.e. dry density, porosity and silt content. In addition, our analysis show that the root : shoot ratio of Z. marina explained > 12 % and the contribution of Z. marina detritus to the sediment surface Corg pool explained > 10 % of the variation in the Corg stocks. The mean monetary value for the present carbon storage and carbon sink capacity of eelgrass meadows in Finland and Denmark, were 281 and 1809 EUR ha−1, respectively. For a more comprehensive picture of seagrass carbon storage capacity, we conclude that future blue carbon studies should, in a more integrative way, investigate the interactions between sediment biogeochemistry, seascape structure, plant species architecture and the hydrodynamic regime.

Large-scale static acoustic survey of a low-density population—Estimating the abundance of the Baltic Sea harbor porpoise

2014 ◽  
Vol 136 (4) ◽  
pp. 2248-2248 ◽  
Author(s):  
Jens C. Koblitz ◽  
Mats Amundin ◽  
Julia Carlström ◽  
Len Thomas ◽  
Ida Carlén ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Large Scale ◽  
Low Density ◽  
Acoustic Survey ◽  
Harbor Porpoise ◽  
The Baltic Sea ◽  
The Baltic ◽  
Density Population

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

1973 ◽  
Vol 31 ◽  
pp. 444-445
Author(s):  
P.J. Killingworth ◽  
M. Warren
Keyword(s):  
Electron Beam ◽  
Organic Materials ◽  
Operating Parameters ◽  
Low Density ◽  
Beam Diameter ◽  
Incident Electron Beam ◽  
Specimen Material ◽  
Voltage Compensation ◽  
Selection Of ◽  
Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

Intralysosomal Accumulation of Colloidal Gold-Low Density Lipoprotein Conjugates in Chloroquine-Treated Fibroblasts

1985 ◽  
Vol 43 ◽  
pp. 546-547 ◽  
Author(s):  
Dean A. Handley ◽  
Cynthia M. Arbeeny ◽  
Larry D. Witte
Keyword(s):  
Colloidal Gold ◽  
Cultured Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Coated Vesicle ◽  
Low Density ◽  
Cholesterol Esters ◽  
Cultured Fibroblasts ◽  
Surface Receptors ◽  
Ldl Particles

Low density lipoproteins (LDL) are the major cholesterol carrying particles in the blood. Using cultured cells, it has been shown that LDL particles interact with specific surface receptors and are internalized via a coated pit-coated vesicle pathway for lysosomal catabolism. This (Pathway has been visualized using LDL labeled to ferritin or colloidal gold. It is now recognized that certain lysomotropic agents, such as chloroquine, inhibit lysosomal enzymes that degrade protein and cholesterol esters. By interrupting cholesterol ester hydrolysis, chloroquine treatment results in lysosomal accumulation of cholesterol esters from internalized LDL. Using LDL conjugated to colloidal gold, we have examined the ultrastructural effects of chloroquine on lipoprotein uptake by normal cultured fibroblasts.

ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

1996 ◽  
Vol 54 ◽  
pp. 548-549
Author(s):  
Ian M. Anderson
Keyword(s):  
Room Temperature ◽  
Iron Aluminide ◽  
Low Density ◽  
Intermetallic Alloys ◽  
Practical Applications ◽  
Alloying Additions ◽  
Site Distribution ◽  
Good Corrosion Resistance ◽  
Room Temperature Ductility ◽  
The Matrix

B2-ordered iron aluminide intermetallic alloys exhibit a combination of attractive properties such as low density and good corrosion resistance. However, the practical applications of these alloys are limited by their poor fracture toughness and low room temperature ductility. One current strategy for overcoming these undesirable properties is to attempt to modify the basic chemistry of the materials with alloying additions. These changes in the chemistry of the material cannot be fully understood without a knowledge of the site-distribution of the alloying elements. In this paper, the site-distributions of a series of 3d-transition metal alloying additions in B2-ordered iron aluminides are studied with ALCHEMI.A series of seven alloys of stoichiometry Fe50AL45Me5, with Me = {Ti, V, Cr, Mn, Co, Ni, Cu}, were prepared with identical heating cycles. Microalloying additions of 0.2% B and 0.1% Zr were also incorporated to strengthen the grain boundaries, but these alloying additions have little influence on the matrix chemistry and are incidental to this study.

Characterization of machined polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 372-373
Author(s):  
C. W. Price ◽  
E. F. Lindsey ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Surface Finish ◽  
Cell Walls ◽  
Surface Structures ◽  
Efficient Technique ◽  
Low Density ◽  
Polystyrene Foam ◽  
Planar Surfaces ◽  
Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

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