scholarly journals Determination of conversion factors for estimation of subantarctic marine bacterial production measured by 3H-thymidine incorporation methodology

1997 ◽  
Vol 13 ◽  
pp. 121-125 ◽  
Author(s):  
D Delille ◽  
G Cahet
Keyword(s):  
Bacterial Production ◽  
Thymidine Incorporation ◽  
Conversion Factors

Estimation of bacterial production in fresh waters by the simultaneous measurement of [35S]Sulphate and D-[3H]glucose uptake in the dark

1978 ◽  
Vol 24 (8) ◽  
pp. 939-946 ◽  
Author(s):  
P. G. C. Campbell ◽  
J. H. Baker
Keyword(s):  
Bacterial Production ◽  
Membrane Filter ◽  
Outer Edge ◽  
Size Fractionation ◽  
Sulphate Uptake ◽  
Uptake Rates ◽  
Chalk Stream ◽  
Glucose Assimilation ◽  
Heterotrophic Production

Sulphate uptake in the dark by phytoplankton constitutes a severe limitation to the determination of bacterial heterotrophic production from sulphate-uptake rates. Consequently a modification to the 35S-method has been developed involving size fractionation to separate the algae from the bacteria. Both the whole water sample and the algae-free filtrate are incubated in the dark with trace quantities of [3H]glucose, whereas the filtrate alone is incubated with 35SO4. The experimental determined ratio (whole sample glucose assimilation: filtrate glucose assimilation) is used to correct the measured sulphate uptake (filtrate) and yields an estimate of bacterial sulphate uptake in the whole sample.A potential filtration artefact has been demonstrated in the 35SO4 uptake methodology. Excision of the outer edge of the membrane filter and counting of the inner wetted circle alone eliminated this problem and significantly improved the analytical performance of the method: coefficient of variation ~ 5%, detection limit ~ 2 ng S ℓ−1 h−1. The modified [35SO4]–[3H]-glucose method was applied to samples from an English chalk stream: bacterial sulphate uptake was higher during the spring diatom maximum (10.6 ng S ℓ−1 h−1) than 3 weeks later when detritus dominated the seston (4.9 ng S ℓ−1 h−1). We estimate the corresponding rates of formation of particulate (bacterial) carbon to be 0.53 and 0.24 μg C ℓ−1 h−1 respectively.

Determination of conversion factors from air kerma to operational dose equivalent quantities for low-energy X-ray spectra

2006 ◽  
Vol 125 (1-4) ◽  
pp. 198-204 ◽  
Author(s):  
A. Hakanen ◽  
A. Kosunen ◽  
P. Poyry ◽  
M. Tapiovaara
Keyword(s):  
Low Energy ◽  
Dose Equivalent ◽  
Conversion Factors ◽  
X Ray ◽  
Air Kerma
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