Diel variations of marine snow concentration in surface waters and implications for particle flux in the sea

Abstract One of the more fascinating phenomena in nature is animal mass migrations and in oceans and freshwaters, diel variations in depth distribution of zooplankton are a phenomenon that has intrigued scientists for more than a century. In our study, we show that zooplankton are able to assess the threat level of ultraviolet radiation and adjust their depth distribution to this level at a very fine tuned scale. Moreover, predation risk induces a size-structured depth separation, such that small individuals, which we show are less vulnerable to predation than larger, make a risk assessment and continue feeding in surface waters during day, offering a competitive release from down-migrating larger animals. Hence, we mechanistically show that such simple organisms as invertebrate zooplankton are able to make individual, size-specific decisions regarding how to compromise between threats from both predators and UV radiation, and adjust their diel migratory patterns accordingly.

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The formation of large marine snow and its sustained residence in surface waters

Limnology and Oceanography ◽

10.4319/lo.1992.37.1.0063 ◽

1992 ◽

Vol 37 (1) ◽

pp. 63-76 ◽

Cited By ~ 57

Author(s):

Ulf Riebesell

Keyword(s):

Surface Waters ◽

Marine Snow

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Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight:implications for the carbon cycle in the ocean

Marine Ecology Progress Series ◽

10.3354/meps179001 ◽

1999 ◽

Vol 179 ◽

pp. 1-11 ◽

Cited By ~ 88

Author(s):

H Ploug ◽

HP Grossart ◽

F Azam ◽

BB Jørgensen

Keyword(s):

Carbon Cycle ◽

Surface Waters ◽

Southern California ◽

Marine Snow ◽

Carbon Turnover

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Carbon Flux Explorer Optical Assessment of C, N and P Fluxes

10.5194/bg-2018-294 ◽

2018 ◽

Author(s):

Hannah L. Bourne ◽

James K. B. Bishop ◽

Todd J. Wood ◽

Timothy J. Loew ◽

Yizhuang Liu

Keyword(s):

Surface Waters ◽

Carbon Flux ◽

Particle Flux ◽

California Current ◽

Strongly Correlated ◽

Particulate Carbon ◽

Long Term Ecological Research ◽

3D Printed ◽

Regression Slopes

Abstract. The magnitude and controls of particulate carbon exported from surface waters and its remineralization at depth are poorly known. The Carbon Flux Explorer (CFE), a Lagrangian float-deployed imaging sediment trap, has been designed to optically measure the hourly variations of particle flux to kilometer depths for months to seasons while relaying data in near-real time to shore via satellite without attending ships. The main optical proxy of particle load recorded by the CFE, volume-attenuance (VA; units of mATN-cm2), while rigorously defined and highly precise, has not been robustly calibrated in terms of particulate organic carbon (POC), nitrogen (PN), and phosphorus (PP). In this study, a novel 3D printed particle sampler using cutting edge additive manufacturing was developed and integrated with the CFE. Two such modified floats (CFE-Cals) were deployed a total of 15 times for 18-24-hour periods to gain calibration imagery and samples at depths near 150 meters in four contrasting productivity environments during the June 2017 California Current Ecosystem – Long Term Ecological Research (LTER) process study. Regression slopes for VA : POC and VA : PN (units mATN-cm2 : mmol; R2 in parentheses) were 10.07 × 103 (0.86), 10.05 × 104 (0.87) respectively and was not sensitive to environment or classes of particles sampled. PP was not strongly correlated with VA.

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Habitat Association of Klebsiella Species

Infection Control ◽

10.1017/s0195941700062603 ◽

1985 ◽

Vol 6 (2) ◽

pp. 52-58 ◽

Cited By ~ 111

Author(s):

Susan T. Bagley

Keyword(s):

Drinking Water ◽

Gastrointestinal Tract ◽

Surface Waters ◽

Industrial Effluents ◽

Opportunistic Pathogen ◽

Habitat Associations ◽

Habitat Association ◽

Klebsiella Species ◽

Almost All ◽

Polluted Waters

AbstractThe genus Klebsiella is seemingly ubiquitous in terms of its habitat associations. Klebsiella is a common opportunistic pathogen for humans and other animals, as well as being resident or transient flora (particularly in the gastrointestinal tract). Other habitats include sewage, drinking water, soils, surface waters, industrial effluents, and vegetation. Until recently, almost all these Klebsiella have been identified as one species, ie, K. pneumoniae. However, phenotypic and genotypic studies have shown that “K. pneumoniae” actually consists of at least four species, all with distinct characteristics and habitats. General habitat associations of Klebsiella species are as follows: K. pneumoniae—humans, animals, sewage, and polluted waters and soils; K. oxytoca—frequent association with most habitats; K. terrigena— unpolluted surface waters and soils, drinking water, and vegetation; K. planticola—sewage, polluted surface waters, soils, and vegetation; and K. ozaenae/K. rhinoscleromatis—infrequently detected (primarily with humans).

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Radiation Damage, Contrast and Statistics in High Resolution Biological Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068291 ◽

1970 ◽

Vol 28 ◽

pp. 260-261

Author(s):

Robert M. Glaeser

Keyword(s):

High Resolution ◽

Particle Flux ◽

Unit Area ◽

Signal To Noise ◽

Resolution Image ◽

High Resolution Image ◽

Pass Through ◽

Counting Statistics ◽

The Relationship ◽

Picture Element

It is well known that a large flux of electrons must pass through a specimen in order to obtain a high resolution image while a smaller particle flux is satisfactory for a low resolution image. The minimum particle flux that is required depends upon the contrast in the image and the signal-to-noise (S/N) ratio at which the data are considered acceptable. For a given S/N associated with statistical fluxtuations, the relationship between contrast and “counting statistics” is s131_eqn1, where C = contrast; r2 is the area of a picture element corresponding to the resolution, r; N is the number of electrons incident per unit area of the specimen; f is the fraction of electrons that contribute to formation of the image, relative to the total number of electrons incident upon the object.

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In situ irradiation effects studies in medium- and high-voltage TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137549 ◽

1995 ◽

Vol 53 ◽

pp. 234-235

Author(s):

Charles W. Allen

Keyword(s):

Cross Section ◽

Particle Flux ◽

Threshold Value ◽

High Energy ◽

Irradiation Damage ◽

Defect Complexes ◽

Lattice Position ◽

Electrons And Ions ◽

The Masses

With respect to structural consequences within a material, energetic electrons, above a threshold value of energy characteristic of a particular material, produce vacancy-interstial pairs (Frenkel pairs) by displacement of individual atoms, as illustrated for several materials in Table 1. Ion projectiles produce cascades of Frenkel pairs. Such displacement cascades result from high energy primary knock-on atoms which produce many secondary defects. These defects rearrange to form a variety of defect complexes on the time scale of tens of picoseconds following the primary displacement. A convenient measure of the extent of irradiation damage, both for electrons and ions, is the number of displacements per atom (dpa). 1 dpa means, on average, each atom in the irradiated region of material has been displaced once from its original lattice position. Displacement rate (dpa/s) is proportional to particle flux (cm-2s-1), the proportionality factor being the “displacement cross-section” σD (cm2). The cross-section σD depends mainly on the masses of target and projectile and on the kinetic energy of the projectile particle.

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Identifying Sources of Sulfate Aerosols Reaching Whiteface Mountain, NY

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117546 ◽

1985 ◽

Vol 43 ◽

pp. 98-101

Author(s):

James S. Webber

Keyword(s):

Trace Metals ◽

Acid Deposition ◽

Surface Waters ◽

Dry Deposition ◽

Coal Combustion ◽

Public Awareness ◽

Sulfate Aerosols ◽

Wet And Dry Deposition ◽

Whiteface Mountain ◽

Toxic Trace Metals

INTRODUCTION“Acid rain” and “acid deposition” are terms no longer confined to the lexicon of atmospheric scientists and 1imnologists. Public awareness of and concern over this phenomenon, particularly as it affects acid-sensitive regions of North America, have increased dramatically in the last five years. Temperate ecosystems are suffering from decreased pH caused by acid deposition. Human health may be directly affected by respirable sulfates and by the increased solubility of toxic trace metals in acidified waters. Even man's monuments are deteriorating as airborne acids etch metal and stone features.Sulfates account for about two thirds of airborne acids with wet and dry deposition contributing equally to acids reaching surface waters or ground. The industrial Midwest is widely assumed to be the source of most sulfates reaching the acid-sensitive Northeast since S02 emitted as a byproduct of coal combustion in the Midwest dwarfs S02 emitted from all sources in the Northeast.

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