International Journal of Water Resources and Environmental Engineering Vol. 4(8), pp. 270-274, August 2012 Available online at http://www.academicjournals.org/IJWREE DOI: 10.5897/IJWREE12.025 ISSN 1991-637X ©2012 Academic Journals Full Length Research Paper Assessment of atmospheric moisture using hygroscopic salts in dry-and-wet climate of Nigeria A. O. Eruola 1,2 *, G. C. Ufoegbune 1 , A. A. Amori 1 and I. O. Ogunyemi 2 1 University of Agriculture, Abeokuta, Ogun State, Nigeria. 2 Yaba College of Technology, Yaba, Lagos, Nigeria. Accepted 19 July, 2012 Atmospheric moisture content plays an important role in climate changes studies. Atmospheric moisture content was determined using four different hygroscopic salts, viz Sodium chloride (NaCl), Potassium chloride (KCl), Zinc sulphate (ZnSO 4 ) and Magnesium chloride (MgCl 2 ) salts and hygrometer. Evaluation of different hygroscopic salts for the determination of humidity was based on the ability of the salts to absorb atmospheric moisture. The affinity of salts for atmospheric water from measured value was compared with the hygrometer measured value. Data were subjected to one-way ANOVA using the Genstat statistical package (Release 4.24 Discovery Edition) to determine the weekly average of the moisture content and bulb depression. Duncan Multiple Range Test (DMRT), T-test and a linear regression model equation was generated with the fitness within 95%. The model of the regression was tested to determine the accuracy of equation compared with wet and dry bulb thermometer depression value. Magnesium chloride (MgCl 2 ) offers the best result with significant coefficient (P = 0.01 and 0.05) and depression value of wet and dry bulb thermometer. The relative reliability of the use of hygroscopic salts in terms of accuracy of both measured and extrapolated humidity data utilization showed that these salts could be used in place of the usual hygrometer. Key words: Hygroscopic salts, hygrometer, atmospheric moisture, humidity. INTRODUCTION Most studies on climate change focus on changes in temperature and precipitation neglecting the atmospheric moisture (relative humidity) which is equally very important not only because of its effect on human comfort but also because either excessively moist or excessively dry conditions can be detrimental to equipment, furniture, buildings and the like (Mitchell et al., 1995). Atmospheric water vapor is one of the most important factors in determining earth's weather and climate. It play a vital role as a greenhouse gas, as an environmental condition which influences the growth of the plants, health of man, pollution of environment (Nieuwolt, 1972) and also transpiration rate which is determined by a balance between the amount of energy available to convert water from the liquid to vapor phase and the moisture gradient. Studies have shown that humidity measurement is among the more difficult problems in basic meteorology. *Corresponding author. E-mail: layosky@yahoo.com. In particular, the most widely used hygrometer (psychrometer) in Nigeria is not reliable (Smadi, 2006). One major problem in the use of hygrometer (psychrometer) is the use of water rather than air (which is a much less effective heat transfer medium) for hygrometers calibration (Murray, 1967). The use of water causes hygrometer to be subjected to drift consequently requiring regular recalibration. A further difficulty is that most hygrometers sense relative humidity rather than the absolute amount of water present. However, research has shown that some hygrometer works on the principle of absorbed moisture in which a known volume of gas passes over a hygroscopic or moisture-absorbing material. The use of moisture-absorbing materials has been acclaimed to be the most accurate way of mea- suring humidity (Jackson, 1986b). Research into the application of humidity have been extensive in nearly all the eco-climatic zones of Nigeria; however, in contrast research endeavor in humidity measurement particularly the use of hygroscopic or moisture-absorbing materials is rare. It is therefore not surprising that humidity