scholarly journals The ecological half-life of radiocesium in surficial bottom sediments of five ponds in Fukushima based on in situ measurements with plastic scintillation fibers

2020 ◽  
Vol 22 (7) ◽  
pp. 1566-1576
Author(s):  
Estiner Walusungu Katengeza ◽  
Yukihisa Sanada ◽  
Kazuya Yoshimura ◽  
Kotaro Ochi ◽  
Takeshi Iimoto
Keyword(s):  
Bottom Sediments ◽  
Half Life ◽  
Surface Sediments ◽  
In Situ Measurements ◽  
Plastic Scintillation

Ecological half-life (Teco) of 137Cs concentration over wide pond areas of surface sediments was evaluated from in situ monitoring with plastic scintillation fibers (PSF) between 2013 and 2019.

Distribution of oxygen in surface sediments from central Sagami Bay, Japan: In situ measurements by microelectrodes and planar optodes

2005 ◽  
Vol 52 (10) ◽  
pp. 1974-1987 ◽  
Author(s):  
Ronnie N Glud ◽  
Frank Wenzhöfer ◽  
Anders Tengberg ◽  
Mathias Middelboe ◽  
Kazumasa Oguri ◽  
...  
Keyword(s):  
Surface Sediments ◽  
In Situ Measurements ◽  
Sagami Bay

Sedimentation and Digestion on Pond Bottoms – An Attempt to Establish a Short-Term Material Balance

1987 ◽  
Vol 19 (12) ◽  
pp. 153-159 ◽  
Author(s):  
A. Iwema ◽  
J. Carré ◽  
D. Minot
Keyword(s):  
Bottom Sediments ◽  
Material Balance ◽  
Gas Production ◽  
In Situ Measurements ◽  
Short Term ◽  
Stabilization Pond ◽  
Pond System ◽  
Origin Identification

Sedimentation and digestion have been measured in situ on the bottom of the first (facultative) and the last (maturation) pond of a wastewater stabilization pond system during six periods of one week. Calculated dry solids balances of the ponds bottoms showed that most of the collected solids would have an endogenous origin. Identification of the collected solids by digestion in the laboratory and supplemental in situ measurements in winter, when gas production was low, allowed the conclusion that the collected solids actually were fairly stabilized bottom sediments which are resuspended by the vigorous gas production. The establishment of a short term sedimentation-digestion balance appears to be a practical impossibility on an actively fermenting pond bottom.

The English–Wabigoon River System: II. Suppression of Mercury and Selenium Bioaccumulation by Suspended and Bottom Sediments

1983 ◽  
Vol 40 (12) ◽  
pp. 2218-2227 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner
Keyword(s):  
Bottom Sediments ◽  
Food Chain ◽  
Organic Material ◽  
Aquatic Ecosystems ◽  
Surface Sediments ◽  
River System ◽  
Fine Particulates ◽  
Mercury Bioaccumulation ◽  
Presence And Absence

Bioaccumulation of 203Hg and 75Se by several members of the food chain, including fish, was followed in large in situ enclosures in the presence and absence of organic-poor sediment. When the sediment was absent, 203Hg was bioaccumulated 8- to 16-fold faster than when it was either suspended in the water or present on the bottom of the enclosures. Mercury-contaminated and uncontaminated sediments were equally effective at reducing the rate of radiolabeled mercury bioaccumulation, apparently by binding the mercury to fine particulates making it less available for methylation and/or bioaccumulation. Based on these results, a mercury ameliorating procedure involving semicontinuous resuspension of organic-poor sediments with downstream deposition onto surface sediments is suggested. The presence of sediments, in the water or on the bottom of enclosures, also reduced radiolabeled selenium bioaccumulation. The degree of inhibition (2- to 10-fold) may have been related to the concentration of organic material in the predominantly inorganic sediments. Implications of this research with respect to mercury–selenium interactions in aquatic ecosystems are discussed.

The Carbon:²³⁴Thorium ratios of sinking particles in the California Current Ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model

2019 ◽  
Author(s):  
Michael Stukel ◽  
Thomas Kelly
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Particulate Organic Carbon ◽  
Transport Model ◽  
California Current ◽  
In Situ Measurements ◽  
Power Law Distribution ◽  
Sinking Particles ◽  
Organic Carbon Concentration

Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon:thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U-234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.

Evaluation of reanalysis and satellite-based sea surface winds using in situ measurements from Chinese Antarctic Expeditions

2013 ◽  
Vol 24 (3) ◽  
pp. 147
Author(s):  
Ming LI ◽  
Qinghua YANG ◽  
Jiechen ZHAO ◽  
Lin ZHANG ◽  
Chunhua LI ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Sea Surface ◽  
Surface Winds ◽  
Sea Surface Winds
Sign in / Sign up

Export Citation Format

Share Document