Moisture Carryover Research Articles

Effects of moisture on the cold vapour determination of mercury and its removal by use of membrane dryer tubes

Continuous-flow vapour generation is now a well-established sample-introduction technique for mercury and the hydride-forming elements. One of the problems associated with this technique is moisture carryover, which originates during the gas–liquid separation process. Excessive moisture carryover causes gradual loss in sensitivity and baseline drift for atomic absorption and atomic fluorescence spectrometry and inductively coupled plasma detection system. Chemical desiccants and physical moisture traps can be used to reduce moisture for short periods of time, although these may give rise to contamination and analyte losses. A more effective way to remove moisture carryover has been found by using a semi-permeable Nafion membrane dryer tube, which continuously desolvates the wet gaseous stream. This device improved the long-term stability and enhanced sensitivity. A relative standard deviation of 2% was achieved for 90 runs of a 1 µg l–1 standard, obtained over a period of 3 h.

Impact of Rainfall Enhancement on Hydrology

Three watersheds in Kansas were investigated to determine the hydrologic effects of a large-scale rainfall augmentation program. The Kansas Watershed Model was used to compare historical with augmented moisture budgets. The augmentation scheme involved 75% increase for rainfalls 1 in. The three watersheds yielded average increased rainfalls of more than 2 in. annually, of which greater than 20% became runoff and greater than 70% evapotranspired. The additional runoff was mostly a result of increased base flow and a major proportion of the increased evapotranspiration occurred during dry periods. Optimal benefits would accrue as a result of long-term seeding programs because of accumulated moisture carryover effects.