δ18O of water vapour, evapotranspiration and the sites of leaf water evaporation in a soybean canopy

Porous membranes find natural application in various fields and industries. Water condensation on membranes can block pores, reduce vapour transmissibility, and diminish the porous membranes' performance. This research investigates the rate of water vapour transmission through microporous nylon and nanofibrous Gore-Tex membranes. Testing consisted of placing the membrane at the intersection of two chambers with varied initial humidity conditions. One compartment is initially set to a high ([Formula: see text]water vapour concentration and the other low ([Formula: see text], with changes in humidity recorded as a function of time. The impact of pore blockage was explored by pre-wetting the membranes with water or interposing glycerine onto the membrane pores before testing. Pore blockage was measured using image analysis for the nylon membrane. The mass flow rate of water vapour ( ṁv) diffusing through a porous membrane is proportional to both its area (A) and the difference in vapour concentration across its two faces ([Formula: see text], such that [Formula: see text] where K is defined as the moisture diffusion coefficient. Correlations are presented for the variation of K as a function of [Formula: see text]. Liquid contamination on the porous membrane has been shown to reduce the moisture diffusion rate through the membrane due to pore blockage and the subsequent reduced open area available for vapour diffusion. Water evaporation from the membrane's surface was observed to add to the mass of vapour diffusing through the membrane. A model was developed to predict the effect of membrane wetting on vapour diffusion and showed good agreement with experimental data.

Download Full-text

Leaf water δ18O reflects water vapour exchange and uptake by C3 and CAM epiphytic bromeliads in Panama

Functional Plant Biology ◽

10.1071/fp21087 ◽

2021 ◽

Author(s):

Monica Mejia-Chang ◽

Casandra Reyes-Garcia ◽

Ulli Seibt ◽

Jessica Royles ◽

Moritz T. Meyer ◽

...

Keyword(s):

Water Vapour ◽

Leaf Water ◽

Epiphytic Bromeliads

Download Full-text

Influence of leaf water potential on diurnal changes in CO2 and water vapour fluxes

Boundary-Layer Meteorology ◽

10.1007/s10546-007-9164-y ◽

2007 ◽

Vol 124 (2) ◽

pp. 161-181 ◽

Cited By ~ 7

Author(s):

Qiang Yu ◽

Shouhua Xu ◽

Jing Wang ◽

Xuhui Lee

Keyword(s):

Water Potential ◽

Water Vapour ◽

Leaf Water Potential ◽

Leaf Water ◽

Diurnal Changes ◽

Water Vapour Fluxes

Download Full-text

The 18 O‐signal transfer from water vapour to leaf water and assimilates varies among plant species and growth forms

Plant Cell & Environment ◽

10.1111/pce.13682 ◽

2019 ◽

Vol 43 (2) ◽

pp. 510-523

Author(s):

Marco M. Lehmann ◽

Gregory R. Goldsmith ◽

Cathleen Mirande‐Ney ◽

Rosemarie B. Weigt ◽

Leonie Schönbeck ◽

...

Keyword(s):

Water Vapour ◽

Plant Species ◽

Leaf Water ◽

Growth Forms ◽

Signal Transfer

Download Full-text

The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations

10.5194/bg-2017-471 ◽

2017 ◽

Author(s):

Anne Alexandre ◽

Amarelle Landais ◽

Christine Vallet-Coulomb ◽

Clément Piel ◽

Sébastien Devidal ◽

...

Keyword(s):

Water Vapor ◽

Relative Humidity ◽

Oxygen Isotope ◽

Soil Water ◽

Isotope Composition ◽

Leaf Water ◽

Growth Chamber ◽

Water Evaporation ◽

Atmospheric Humidity ◽

Oxygen Isotope Fractionation

Abstract. Continental atmospheric relative humidity (RH) is a key climate-parameter. Combined with atmospheric temperature, it allows us to estimate the concentration of atmospheric water vapor which is one of the main components of the global water cycle and the most important gas contributing to the natural greenhouse effect. However, there is a lack of proxies suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility to make model-data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess (17O-excess = ln (δ17O + 1) − 0.528 × ln (δ18O + 1)), in water, water vapor and minerals. The 17O-excess represents an alternative to deuterium-excess for investigating relative humidity conditions that prevail during water evaporation. Phytoliths are micrometric amorphous silica particles that form continuously in living plants. Phytolith morphological assemblages from soils and sediments are commonly used as past vegetation and hydrous stress indicators. In the present study, we examine whether changes in atmospheric RH imprint the 17O-excess of phytoliths in a measurable way and whether this imprint offers a potential for reconstructing past RH. For that purpose, we first monitored the 17O-excess evolution of soil water, grass leaf water and grass phytoliths in response to changes in RH (from 40 to 100 %) in a growth chamber experiment where transpiration reached a steady state. Decreasing RH decreases the 17O-excess of phytoliths by 4.1 per meg / % as a result of kinetic fractionation of the leaf water subject to evaporation. In order to model with accuracy the triple oxygen isotope fractionation in play in plant water and in phytoliths we recommend direct and continuous measurements of the triple isotope composition of water vapor. Then, we measured the 17O-excess of 57 phytolith assemblages collected from top soils along a RH and vegetation transect in inter-tropical West and Central Africa. Although scattered, the 17O-excess of phytoliths decreases with RH by 3.4 per meg / %. The similarity of the trends observed in the growth chamber and nature supports that RH is an important control of 17O-excess of phytoliths in the natural environment. However, other parameters such as changes in the triple isotope composition of the soil water or phytolith origin in the leaf tissue may come into play. Assessment of these parameters through additional growth chambers experiments and field campaigns will bring us closer to an accurate proxy of changes in relative humidity.

Download Full-text

The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations

Biogeosciences ◽

10.5194/bg-15-3223-2018 ◽

2018 ◽

Vol 15 (10) ◽

pp. 3223-3241 ◽

Cited By ~ 7

Author(s):

Anne Alexandre ◽

Amarelle Landais ◽

Christine Vallet-Coulomb ◽

Clément Piel ◽

Sébastien Devidal ◽

...

Keyword(s):

Water Vapor ◽

Relative Humidity ◽

Oxygen Isotope ◽

Soil Water ◽

Isotope Composition ◽

Leaf Water ◽

Growth Chamber ◽

Water Evaporation ◽

Atmospheric Humidity ◽

Oxygen Isotope Fractionation

Abstract. Continental atmospheric relative humidity (RH) is a key climate parameter. Combined with atmospheric temperature, it allows us to estimate the concentration of atmospheric water vapor, which is one of the main components of the global water cycle and the most important gas contributing to the natural greenhouse effect. However, there is a lack of proxies suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility of making model–data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess (17O-excess = ln (δ17O + 1) – 0.528 × ln (δ18O + 1)), in water, water vapor and minerals. The 17O-excess represents an alternative to deuterium-excess for investigating relative humidity conditions that prevail during water evaporation. Phytoliths are micrometric amorphous silica particles that form continuously in living plants. Phytolith morphological assemblages from soils and sediments are commonly used as past vegetation and hydrous stress indicators. In the present study, we examine whether changes in atmospheric RH imprint the 17O-excess of phytoliths in a measurable way and whether this imprint offers a potential for reconstructing past RH. For that purpose, we first monitored the 17O-excess evolution of soil water, grass leaf water and grass phytoliths in response to changes in RH (from 40 to 100 %) in a growth chamber experiment where transpiration reached a steady state. Decreasing RH from 80 to 40 % decreases the 17O-excess of phytoliths by 4.1 per meg/% as a result of kinetic fractionation of the leaf water subject to evaporation. In order to model with accuracy the triple oxygen isotope fractionation in play in plant water and in phytoliths we recommend direct and continuous measurements of the triple isotope composition of water vapor. Then, we measured the 17O-excess of 57 phytolith assemblages collected from top soils along a RH and vegetation transect in inter-tropical West and Central Africa. Although scattered, the 17O-excess of phytoliths decreases with RH by 3.4 per meg/%. The similarity of the trends observed in the growth chamber and nature supports that RH is an important control of 17O-excess of phytoliths in the natural environment. However, other parameters such as changes in the triple isotope composition of the soil water or phytolith origin in the plant may come into play. Assessment of these parameters through additional growth chambers experiments and field campaigns will bring us closer to an accurate proxy of changes in relative humidity.

Download Full-text

Leaf Wax Extracted from Cauliflower Waste Shows Antitranspirant Efficacy

10.21203/rs.3.rs-210747/v1 ◽

2021 ◽

Author(s):

Gee-Sian Leung ◽

Ray Marriott ◽

Michele Faralli ◽

Minuka Weerasinghe ◽

Fiona Corke ◽

...

Keyword(s):

Stomatal Conductance ◽

Economic Analysis ◽

Water Vapour ◽

Crop Productivity ◽

Leaf Water ◽

Plant Leaves ◽

Biological Efficacy ◽

Leaf Wax ◽

Cost Of Production ◽

Main Component

Abstract Purpose : Excessive transpiration of water from plant leaves can damage crop productivity during droughts, but commercial antitranspirants are expensive. The aim of this research was to characterise extracted wax from brassica leaf waste, and determine its antitranspirant efficacy and economics. Methods : Yield of wax extracted with dichloromethane from six types of brassica waste was measured and the highest yielding waste was selected for bulk extraction with supercritical CO 2 . Wax was compared with a commercially-available terpene antitranspirant (di-1- p -menthene) for efficacy in reducing leaf water vapour loss, measured as stomatal conductance, in three experiments on rapeseed and in one experiment on wheat. Cost of wax under different production scenarios was calculated. Results : Cauliflower leaf waste gave the highest wax yield, with the concentration varying from 1.31% (m/m) to 5.85% (m/m) in different batches of dried leaves. Nonacosane was the main component of the wax. In two of the three rapeseed experiments and in the wheat experiment, stomatal conductance was significantly reduced to similar extents by wax and by di-1- p -menthene, despite the wax being formulated and applied at a much lower concentration. Economic analysis showed that a high wax concentration in the cauliflower leaves would be needed to produce a commercially-viable leaf wax antitranspirant. Conclusion : The results demonstrate biological efficacy as an antitranspirant of extracted cauliflower leaf wax. Further research is needed on variation in wax yield to reliably source high wax concentration leaves and reduce cost of production, and also to understand the greater efficacy of wax than di-1- p -menthene.

Download Full-text