3 ms·

Water boils at 212F, melts at 32F. It is a sufficient model of evcaporation. For dicamaba to have a sufficient concentration to harm (even targeted plants) it m

Water boils at 212F, melts at 32F. It is a sufficient model of evcaporation. For dicamaba to have a sufficient concentration to harm (even targeted plants) it must be rather concentrated, compared to what one might find in concentrations produced by condensation (one field over). Having a degree in organic chemistry and thousands of hours of bench chemistry, I can speak with some authority on the matter.

logfromblammo 9y ago
Liquid water has a vapor pressure, dependent mostly on temperature. When this vapor pressure exceeds the partial pressure of the water in the gas phase, water crosses the phase barrier. This is how you can have trace measurements of water vapor in (1 bar) air that is cooler than 100 degC. Some volatile chemicals--such as the acetone in nail polish remover--are detectable as odors even when their temperature is well below their boiling point. This is the liquid phase establishing an equilibrium with the gas phase at that temperature. The most energetic molecules in the liquid escape into the gas (cooling the liquid in the process). Imagine a lake in a desert. The maximum daytime temperature in that desert is 40 degC, well below the boiling point of 100 degC. The lake has no outflows. Over the course of a month, the lake disappears. Where did the water go? It evaporated, and the water in the gas phase blew away and was replaced by dry air, thus allowing more of the liquid water to evaporate. If you put an airtight dome over it, the lake would stay put, and the air in the dome would get very humid. You would probably also be able to see condensation on its walls, as the vapor movement continuously transfers heat from the lake to the dome. The dicamba is likely evaporating from the soil into air with no gaseous dicamba in it, blowing to adjacent fields, and the plants are uptaking it as a gas via their normal respiration. No condensation is required, for the same reason that plants don't eat dry ice to get their CO2. Once inside the plant, the vapor dicamba is free to dissolve into the plant's own water. It is not necessary for it to dissolve in water outside the plant to be taken up by the roots. Those plant cells might not have a lot of water in them, or they might be filled to bursting with it. Plants have to deal with deluge and drought differently than we animals do. The questions everyone have to ask are what concentration of dicamba is damaging to the plant, and what is the exact relationship between wind, distance, ambient moisture, and concentration? By calculating from the vapor pressure vs temperature of the chemical, and solubility, you should be able to draw a plume-shaped area on a map that shows where dicamba-vulnerable plants will die after an application. If plants outside that area die, something in your model is wrong. And people are claiming that plants outside the area are dying. What part of the model is wrong? Based on the article, it seems like the volatility is off.
deleted 9y ago
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amigoingtodie 9y ago
Vacuum chamber much, you lovable absolutist?!?

logfromblammo 9y ago

Liquid water has a vapor pressure, dependent mostly on temperature. When this vapor pressure exceeds the partial pressure of the water in the gas phase, water crosses the phase barrier. This is how you can have trace measurements of water vapor in (1 bar) air that is cooler than 100 degC. Some volatile chemicals--such as the acetone in nail polish remover--are detectable as odors even when their temperature is well below their boiling point. This is the liquid phase establishing an equilibrium with the gas phase at that temperature. The most energetic molecules in the liquid escape into the gas (cooling the liquid in the process). Imagine a lake in a desert. The maximum daytime temperature in that desert is 40 degC, well below the boiling point of 100 degC. The lake has no outflows. Over the course of a month, the lake disappears. Where did the water go? It evaporated, and the water in the gas phase blew away and was replaced by dry air, thus allowing more of the liquid water to evaporate. If you put an airtight dome over it, the lake would stay put, and the air in the dome would get very humid. You would probably also be able to see condensation on its walls, as the vapor movement continuously transfers heat from the lake to the dome. The dicamba is likely evaporating from the soil into air with no gaseous dicamba in it, blowing to adjacent fields, and the plants are uptaking it as a gas via their normal respiration. No condensation is required, for the same reason that plants don't eat dry ice to get their CO2. Once inside the plant, the vapor dicamba is free to dissolve into the plant's own water. It is not necessary for it to dissolve in water outside the plant to be taken up by the roots. Those plant cells might not have a lot of water in them, or they might be filled to bursting with it. Plants have to deal with deluge and drought differently than we animals do. The questions everyone have to ask are what concentration of dicamba is damaging to the plant, and what is the exact relationship between wind, distance, ambient moisture, and concentration? By calculating from the vapor pressure vs temperature of the chemical, and solubility, you should be able to draw a plume-shaped area on a map that shows where dicamba-vulnerable plants will die after an application. If plants outside that area die, something in your model is wrong. And people are claiming that plants outside the area are dying. What part of the model is wrong? Based on the article, it seems like the volatility is off.

deleted 9y ago

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amigoingtodie 9y ago

Vacuum chamber much, you lovable absolutist?!?