EFFECTS OF HERBICIDES ON CARBON DIOXIDE UPTAKE BY PINE SEEDLINGS

1967 ◽  
Vol 45 (7) ◽  
pp. 961-971 ◽  
Author(s):  
S. Sasaki ◽  
T. T. Kozlowski
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Soil Surface ◽  
Pinus Resinosa ◽  
Spray Application ◽  
Leaf Color ◽  
Carbon Dioxide Uptake ◽  
Chlorophyll Breakdown ◽  
Pine Seedlings ◽  
Steady Rate

Experiments were conducted on effects of herbicides applied to soil or sprayed on shoots on CO2 uptake of 3-year-old Pinus resinosa Ait. seedlings. When applied to the soil, atrazine, monuron, EPTC, and 2,4-D at 20 lb/ac (soil surface basis) or at 4000 p.p.m. variously decreased absorption of CO2. Monuron checked gas exchange most rapidly, with no CO2 uptake measurable after 10 days. Atrazine and 2,4-D inhibited absorption of CO2 at a steady rate. EPTC caused a delayed inhibition of CO2 uptake. DCPA, CDAA, CDEC, and NPA did not affect gas exchange significantly. Monuron applied as a spray depressed CO2 uptake somewhat faster than the soil-applied herbicide. Very rapid inhibition of CO2 uptake was observed after spray application of 2,4-D or EPTC. Atrazine affected gas exchange similarly when applied as a spray or incorporated in the soil. DCPA, applied as a spray, did not affect absorption of CO2 significantly. Possible reasons for differences in CO2 uptake after spray and soil-application of certain herbicides are discussed. Inert ingredients of EPTC applied as sprays at a concentration of 4000 p.p.m. greatly reduced CO2 absorption 3 days after treatment. However, the rapid early depression of gas exchange was followed by recovery, with no obvious deleterious effects on growth up to 3 months after treatment. Some herbicides checked CO2 absorption without chlorophyll breakdown whereas others did not. Monuron completely inhibited CO2 uptake long before any changes in leaf color were evident. In contrast, depression of CO2 absorption by atrazine and 2,4-D rather closely paralleled development of toxicity symptoms, especially chlorosis. These observations suggested that some herbicides such as monuron affected the photosynthetic mechanism more directly than others such as atrazine, 2,4-D, and EPTC.

Responses to Humidity by Stomata of Nicotiana glauca L. And Corylus avellana L. Are Consistent With the Optimization of Carbon Dioxide Uptake With Respect to Water Loss

1980 ◽  
Vol 7 (3) ◽  
pp. 315 ◽  
Author(s):  
GD Farquhar ◽  
ED Schulze ◽  
M Kuppers
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Gas Exchange ◽  
Water Loss ◽  
Corylus Avellana ◽  
Carbon Gain ◽  
Nicotiana Glauca ◽  
Carbon Dioxide Uptake ◽  
Total Conductance ◽  
Corylus Avellana L

Intact leaves of N. glauca and C. avellana were exposed to a range of humidities and their gas exchange monitored. Rates of transpiration and assimilation of carbon dioxide, and their sensitivities to changes in total conductance (leaf and boundary layer) were determined. The ratio of these sensitivities, δE/δA, remained substantially constant over the range of humidities. The results represent the first experimental support for a recent hypothesis that stomata vary their apertures in such a manner as to keep δE/δA constant, which optimizes carbon gain with respect to water loss.

scholarly journals NITRATE REDUCTION AND ASSIMILATION IN CHLORELLA

1948 ◽  
Vol 32 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Marian Cramer ◽  
Jack Myers
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Nitrate Reduction ◽  
Relative Rate ◽  
Chlorella Pyrenoidosa ◽  
Carbon Dioxide Production ◽  
Growth Conditions ◽  
Low Light ◽  
Carbon Dioxide Uptake ◽  
Elementary Analysis

1. Nitrate reduction and assimilation have been studied in Chlorella pyrenoidosa under growth conditions by observing effects on the CO2/O2 gas exchange quotient. 2. During assimilation of glucose in the dark, nitrate reduction is noted as an increase in the R.Q. to about 1.6 caused by an increased rate of carbon dioxide production. 3. During photosynthesis at low light intensity nitrate reduction is evidenced by a reduction in the CO2O2 quotient to about 0.7 caused by a decreased rate of carbon dioxide uptake. 4. Chlorella will assimilate nitrogen from either nitrate or ammonia. When both sources are supplied, only ammonia is utilized and no nitrate reduction occurs. It is inferred that under the usual conditions of growth nitrate is reduced only at a rate required for subsequent cellular syntheses. The effect of nitrate reduction on the CO2O2 quotient therefore provides a measure of the relative rate of nitrogen assimilation. 5. Over-all photosynthetic metabolism may be described from elementary analysis of the cells since excretory products are negligible. The gas exchange predicted in this way is in good agreement with the observed CO2/O2 quotients.

The Exchange of Oxygen and Carbon Dioxide Across the Gills of Rainbow Trout

1967 ◽  
Vol 46 (2) ◽  
pp. 339-348 ◽  
Author(s):  
D. J. RANDALL ◽  
G. F. HOLETON ◽  
E. DON STEVENS
Keyword(s):  
Carbon Dioxide ◽  
Rainbow Trout ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Transfer Factor ◽  
Rate Ratio ◽  
High Capacity ◽  
Salmo Gairdneri ◽  
Moderate Exercise ◽  
Carbon Dioxide Uptake

1. The effectiveness of oxygen uptake by the blood of rainbow trout (Salmo gairdneri) approaches 100%, whereas that for the removal of oxygen from water was only 11-30%. 2. Most of the carbon dioxide is removed from the blood as it passes through the gills, but the effectiveness of carbon dioxide uptake by water is very low, because of the high capacity of water for carbon dioxide compared with oxygen. 3. Moderate exercise had little effect on the effectiveness of gas exchange across the gills. The increased oxygen uptake was facilitated by an increase in the transfer factor of the gills for oxygen. There were small increases in the capacity-rate ratio of blood to water at the gills during moderate exercise. 4. Hypoxia resulted in a marked decrease in the effectiveness of oxygen uptake by the blood, but had little effect on oxygen removal from the water. Gas exchange was facilitated during hypoxia by an increase in transfer factor of the gills, but hindered by an increasing capacity-rate ratio of blood to water at the gills. 5. Gas exchange in an aquatic environment was compared with that in an aerial environment.

Eddy covariance flux measurements of momentum, heat and carbon dioxide in Hudson Bay at the onset of sea ice melt 

2021 ◽  
Author(s):  
Richard Sims ◽  
Brian Butterworth ◽  
Tim Papakyriakou ◽  
Mohamed Ahmed ◽  
Brent Else
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Sea Ice ◽  
Eddy Covariance ◽  
Open Water ◽  
The Arctic ◽  
Gas Transfer ◽  
Hudson Bay ◽  
Flux Measurements ◽  
Ice Fraction

<p>Remoteness and tough conditions have made the Arctic Ocean historically difficult to access; until recently this has resulted in an undersampling of trace gas and gas exchange measurements. The seasonal cycle of sea ice completely transforms the air sea interface and the dynamics of gas exchange. To make estimates of gas exchange in the presence of sea ice, sea ice fraction is frequently used to scale open water gas transfer parametrisations. It remains unclear whether this scaling is appropriate for all sea ice regions. Ship based eddy covariance measurements were made in Hudson Bay during the summer of 2018 from the icebreaker CCGS Amundsen. We will present fluxes of carbon dioxide (CO<sub>2</sub>), heat and momentum and will show how they change around the Hudson Bay polynya under varying sea ice conditions. We will explore how these fluxes change with wind speed and sea ice fraction. As freshwater stratification was encountered during the cruise, we will compare our measurements with other recent eddy covariance flux measurements made from icebreakers and also will compare our turbulent CO<sub>2 </sub>fluxes with bulk fluxes calculated using underway and surface bottle pCO<sub>2</sub> data. </p><p> </p>

Respiration in man during metabolic alkalosis

1962 ◽  
Vol 17 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Daniel J. Stone
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Lung Function ◽  
Gas Exchange ◽  
Metabolic Alkalosis ◽  
Time Lag ◽  
Respiratory Compensation ◽  
Arterial Ph ◽  
Oral Sodium ◽  
Ventilation Response

A steady state metabolic alkalosis was induced in two subjects over a period of several days utilizing oral sodium bicarbonate in dosages of 50 g/day. The purpose of inducing steady state metabolic alkalosis was to study the effects of such a state on the respiratory center responses to inspired gas mixtures, containing carbon dioxide, and to contrast these results with the control studies. The experiment was so designed that the arterial pH in both subjects tended to return toward normal in the presence of significant increases in blood bicarbonate. Repeated study of ventilation responses with room air and 4% and 6% carbon dioxide in inspired air revealed a definite and significant decrease in ventilation response to carbon dioxide during the periods of steady state alkalosis as compared to the control periods. Normal responses returned after some time lag. A consistent rise in paCOCO2 occurred with alkalosis, thus demonstrating respiratory compensation. In neither subject was total lung function or gas exchange affected by the alkalosis. The experiment was confirmed on several occasions with reproducible results. Note: (With the Research Assistance of Mary Di Lieto) Submitted on May 22, 1961

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