Vapour-pressure deficit the plant may dry out and die. For this reason the ideal range for VPD in a greenhouse is from 0.45 kPa to 1.25 kPa, ideally sitting at around 0.85 kPa. As a general rule, most plants grow well at VPDs of between 0.8 and 0.95 kPa. In ecology, it is the difference between the actual water vapour pressure and the saturation water vapour pressure at a particular temperature. Unlike relative humidity, vapour-pressure deficit has a simple nearly straight-line relationship to the rate of evapotranspiration and other measures of evaporation. To compute the VPD, we need the ambient (greenhouse) air
Cold vapour atomic fluorescence spectroscopy Protection Agency (EPA) for measuring mercury in wastewater are in common use. EPA Methods 245.7 and 1631 are commonly used for measurement of industrial wastewater using CVAFS. Other analytical techniques suitable for analyzing heavy metals in air or water: Cold vapour atomic fluorescence spectroscopy Cold vapour atomic fluorescence spectroscopy (CVAFS) is a subset of the analytical technique known as atomic fluorescence spectroscopy (AFS). Used in the measurement of trace amounts of volatile heavy metals such as mercury, cold vapour AFS makes use of the unique characteristic of mercury that allows vapour measurement at room temperature. Free mercury atoms in a