The measurement of primary production and its relation to inorganic phosphate absorption in a freshwater Lake

Hydrobiologia ◽  
1969 ◽  
Vol 34 (3-4) ◽  
pp. 378-391 ◽  
Author(s):  
S. L. Wong
Keyword(s):  
Primary Production ◽  
Inorganic Phosphate ◽  
Freshwater Lake ◽  
Phosphate Absorption

Absorption of Inorganic Phosphate in the Human Small Intestine

1979 ◽  
Vol 56 (5) ◽  
pp. 407-412 ◽  
Author(s):  
J. Walton ◽  
T. K. Gray
Keyword(s):  
Small Intestine ◽  
Inorganic Phosphate ◽  
Water Movement ◽  
Human Subjects ◽  
Sodium Concentration ◽  
Phosphate Concentration ◽  
Phosphate Absorption ◽  
Human Small Intestine ◽  
Intestinal Phosphate Absorption

1. Intestinal phosphate absorption in human subjects was studied by the technique of triple lumen intestinal perfusion in vivo. 2. Ileal phosphate absorption increased as the intraluminal phosphate concentration was increased. 3. Ileal rates of phosphate absorption were lower at any given intraluminal phosphate concentration than previously described jejunal rates. Acidification of the ileal lumen did not increase phosphate absorption. 4. Phosphate absorption was shown in the jejunum to be dependent on the intraluminal sodium concentration. 5. Phosphate absorption in the human small intestine consists of at least two components, one directly proportional to water movement and the second apparently independent of water movement.

scholarly journals Photoheterotrophy by aerobic anoxygenic bacteria modulates carbon fluxes in a freshwater lake

2021 ◽  
Author(s):  
Kasia Piwosz ◽  
Cristian Villena-Alemany ◽  
Izabela Mujakić
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Carbon Fluxes ◽  
Photochemical Reactions ◽  
Freshwater Lake ◽  
Infrared Light ◽  
Community Respiration ◽  
New Paradigm ◽  
Heterotrophic Microorganisms ◽  
Global Carbon

AbstractLakes are a significant component of the global carbon cycle. Respiration exceeds net primary production in most freshwater lakes, making them a source of CO2 to the atmosphere. Driven by heterotrophic microorganisms, respiration is assumed to be unaffected by light, thus it is measured in the dark. However, photoheterotrophs, such as aerobic anoxygenic photoheterotrophic (AAP) bacteria that produce ATP via photochemical reactions, substantially reduce respiration in the light. They are an abundant and active component of bacterioplankton, but their photoheterotrophic contribution to microbial community metabolism remains unquantified. We showed that the community respiration rate in a freshwater lake was reduced by 15.2% (95% confidence interval (CI): 6.6–23.8%) in infrared light that is usable by AAP bacteria but not by primary producers. Moreover, significantly higher assimilation rates of glucose (18.1%; 7.8–28.4%), pyruvate (9.5%; 4.2–14.8%), and leucine (5.9%; 0.1–11.6%) were measured in infrared light. At the ecosystem scale, the amount of CO2 from respiration unbalanced by net primary production was by 3.69 × 109 g CO2 lower over these two sampling seasons when measured in the infrared light. Our results demonstrate that dark measurements of microbial activity significantly bias the carbon fluxes, providing a new paradigm for their quantification in aquatic environments.

Temporal patterns of primary production in a large ultra-oligotrophic Antarctic freshwater lake

Polar Biology ◽  
1997 ◽  
Vol 18 (6) ◽  
pp. 363-370 ◽  
Author(s):  
Peter Bayliss ◽  
J. Cynan Ellis-Evans ◽  
Johanna Laybourn-Parry
Keyword(s):  
Primary Production ◽  
Temporal Patterns ◽  
Freshwater Lake ◽  
Antarctic Freshwater Lake

Research on Nitrogen and Phosphorus Release from Sediments in Small Inland Freshwater Lakes

2013 ◽  
Vol 864-867 ◽  
pp. 248-255 ◽  
Author(s):  
Cheng Rui Xu
Keyword(s):  
Inorganic Phosphate ◽  
Ph Value ◽  
Sedimentary Environment ◽  
Simulation Method ◽  
Phosphorus Release ◽  
Freshwater Lake ◽  
Determination Method ◽  
Freshwater Lakes ◽  
Nitrogen And Phosphorus ◽  
Existing Form

Indoor simulation method was applied to study the characteristics of nitrogen and phosphorus release from sediments in small freshwater lake Huangjia Lake. Meanwhile, the grading determination method of inorganic phosphate was applied to study the existing form of inorganic phosphate in sediments. The results showed that sedimentary environment in various areas of Huangjia Lake would have influence on release of nitrogen and phosphorus. At the same time, the temperature and pH value were proved to have obvious influence on release of nitrogen and phosphorus.

Characteristics of phosphate transport in isolated proximal tubule

1976 ◽  
Vol 231 (3) ◽  
pp. 979-985 ◽  
Author(s):  
VW Dennis ◽  
PB Woodhall ◽  
RR Robinson
Keyword(s):  
Proximal Tubule ◽  
Inorganic Phosphate ◽  
Phosphate Transport ◽  
Phosphate Concentration ◽  
Proximal Tubules ◽  
Rabbit Serum ◽  
Phosphate Absorption ◽  
Glomerular Filtrate ◽  
Straight Portion ◽  
The Mean

The characteristics of inorganic phosphate transport in isolated perfused proximal tubules of the rabbit were examined using radioisotopic techniques. When tubules were perfused with an ultrafiltrate of rabbit serum, the mean lumen-to-bath flux of phosphate in the convoluted segment was 6.60 +/- 1.41 (SE) pmol/mm-min with a simultaneous back-to-lumen flux of 0.45 +/- 0.08. In the straight portion of the proximal tubule, the lumen-to-bath flux was significantly lower (P less than 0.01) at 2.22 +/- 0.48 pmol/min-min with a bath-to-lumen flux of 0.31 +/- 0.05. The lumen-to-bath flux was not affected by increases in the intraluminal phosphate concentration from 2.00 +/- 0.19 to 3.12 +/- 0.34 mM or by the isohydric replacement of bicarbonate in the ambient fluids with chloride. However, phosphate absorption was completely inhibited by ouabain 10(-5) M in the bath. These data indicate that phosphate absorption in these segments occurs by a mechanism other than independent diffusion and is saturated at phosphate concentrations characteristic of normal glomerular filtrate. There is no evidence for significant phosphate transport from bath to lumen.

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