Water balance study

Nyhan, J.W., A seven-year water balance study of an evapotranspiration landfill cover varying in slope for semiarid regions, Vadose Zone Journal, 4, 466-480, 2005. 

Nyhan, J., Hakonson T., and Drennon, B., A water balance study of two landfill cover designs for semi-arid regions, Journal of Environmental Quality, 19, 281-288, 1990. 

Much of what we know about the nutrient stocks of secondary forests is based on soil measurements made to depths of only 0.1 to 1.0 m (Uhl and Jordan, 1984, Buschbacher et al., 1988, Koutika et al. 1997, Neill et al. 1997). However, water balance studies and direct measurements of deep soil moisture and roots provide evidence that forests across much of seasonally dry Amazonia depend upon root systems that extend well beyond this conventional sampling depth to absorb water during the dry season (Nepstad et al. 1994, Jipp et al. 1998, Hodnett et al. 1997, Holscher et al. 1997). The occurrence of root systems extending to 18 m depth in Amazonian forests (Nepstad et al. 1994) demands a re-examination of our thinking about the nutrient stocks of these ecosystems, and the recovery of these nutrient stocks in secondary forests. If the rooting zone of Amazonian forests extends to several meters depth, instead of several centimeters depth, are these forests less vulnerable than previously believed to nutri-... 

The problem with most of the water balance studies of the Aral Sea is that for several decades there were no continuous observations of the sea level, and the few data that do exist are fragmentary or unavailable. Because the historical sea volume cannot be determined accurately, there are large uncertainties in the water... 

The very first studies with radiation crosslinked polyethylene oxide (PEO) have shown that SAH is able to substantially reduce the sensitivity of plants to water shortage [7], to promote their growth, particularly, under conditions of water deficiency [8], to improve seedling survival and the final crop [9], These results stimulated a more detailed analysis of the effects of SAH in the water balance of... 

Weather station/ weather data requirements A On-site weather station is preferred and may be mandatory for certain studies. Minimally, a station must be located within 10 km of test site In certain cases, a weather station located within 10 km of the test site may be sufficient. If water balances are to be determined, an on-site weather station is necessary to measure, at a minimum, precipitation, solar radiation, wind speed, relative humidity, and air temperature... 

Data on weather conditions, especially temperature and rainfall (temporal distribution and intensity) in the study area are essential for the evaluation of the dissipation data. It is very important to understand the water balance in the paddy field as accurately as possible when calculating the rate of outflow. Records of changes in water temperature and sediment temperature are also helpful for modeling the behavior of a chemical in the rice paddy field. 

Water balance. Before an existing system can be studied from the point of view of water consumption and effluent treatment, the first step must be to establish a water balance. For a new design, this is a question simply of extracting the information relating to water streams from the flowsheets... 

Krupa, J. (1964). Studies on the physiology of germination of spores of Funaria hygrometrica (Sibth.). I. The influence of light on germination with respect to water balance and respiratory processes. Acta Societatis Botanicorum Poloniae 33 177-192. 

The microscopic approach looks at heterogeneous properties of the tissue and has been developed for plant material on the basis of plant physiology studies on the effect of osmosis on water balance and transport in growing plants. 

Effect of CCI4 Intoxication on Water Balance in Rainbow Trout. In studies of water balance the urinary bladder of treated and control animals was catheterized (PE 50 tubing) and individual fish were placed in plexiglass restraining chambers for 24 h to allow urine flow rates to stabilize. 

In another study, Nakajima, Konomi, and Kitahara [144] studied the water accumulation in different components of the fuel cell at simulated start-up cycles. Each component was weighed before and after each test once a test was completed, water balance analysis was performed. Through this analysis, the effect of different diffusion layers was probed in detail, and it was concluded that the DLs with higher gas permeability were able to remove water more efficiently. It was also observed that the MPL was effective in improving start-up performance of the fuel cell by suppressing water accumulation at the CL and within the DL. 

In DMFCs, the water balance analytical method has been used as a tool to study the fuel (methanol) and water crossover from the anode toward the cathode. Xu, Zhao, and He [120] and Xu and Zhao [180] performed a thorough investigation of how different cathode DLs and MPLs affected the total water crossover from the anode side. In order to be able to perform the water balance equations, they also collected the water at both outlets of the cell. This analysis technique was vital for them to be able to observe how different characteristics for fhe cafhode DL affect not only the overall performance of the fuel cell buf also fhe nef wafer drag coefficient and water crossover in DMFCs. 

Distributions of water and reactants are of high interest for PEFCs as the membrane conductivity is strongly dependent on water content. The information of water distribution is instrumental for designing innovative water management schemes in a PEFC. A few authors have studied overall water balance by collection of the fuel cell effluent and condensation of the gas-phase water vapor. However, determination of the in situ distribution of water vapor is desirable at various locations within the anode and cathode gas channel flow paths. Mench et al. pioneered the use of a gas chromatograph for water distribution measurements. The technique can be used to directly map water distribution in the anode and cathode of an operating fuel cell with a time resolution of approximately 2 min and a spatial resolution limited only by the proximity of sample extraction ports located in gas channels. 

It has become Increasingly obvious to us that regulation of water balance In Insects Is one of the keys to the success of these animals In their adaptation to such a wide variety of habitats. The complexities Involved In undertaking studies of such systems may require expansion of our Interdisciplinary approach so as to Include such diverse fields as biophysics, ecology, and cell biology. The subject Is a fascinating one, perhaps all the more so due to Its complexity, and promises to open up new areas In which Interdisciplinary research will play a role. 

Isotopes of oxygen and hydrogen are useful tracers of water sources because they are constituents of the water molecule itself and because they are conservative in aquifers at near-surface temperatures. Isotopic techniques take advantage of the fact that lakes and their surrounding ground-water systems are usually isotopically distinct. Applications of stable isotopes for the study of lakes were first described by Dincer (10) and were discussed in several subsequent review articles (11-14). Most applications of isotopic techniques to lake systems are designed for the determination of water balances, nutrient-uptake studies, and paleotemperature reconstructions. 

The increased input of nutrients and other pollutants to rivers and estuaries may have been exacerbated by the destruction of large areas of fresh and salt water wetlands, often for agriculture (Figs 2 and 3). For example, in the United States, in 1950 there were over 100,000,000 acres (over tOx I0 > hectares) of wetlands being drained (Shaw and Fredine, 1956). The impact of wetlands on water quality is difficult to quantify (Nixon, 1980), but the few annual mass balance studies that are available indicate that these environments serve as sinks (though of widely varying strength) for nutrients (Fig. 4) and a number of... 

Fig. 4. The results of annual mass balance studies for a number of fresh and salt water wetland areas receiving different levels of nutrient input. From Nixon and Lee (in press).

S. Kjelleberg, B. Norkrans, H. Lofgren and K. Larsson, Surface balance study of interaction between microorganisms and a lipid monolayer at the air-water interface, Appl. Environmental Microbiol. 31 (1976) 609-611. 

Alekin O.A. (1978) Water erosion of land surface. In U.S.S.R. Committee for the Internatl. Hydrol. Decade World Water Balance and Water Resources of the Earth, Studies and Reports in Hydrology, 25, UNESCO Press, Paris, 663 pp. 

Mean daily balances (excluding loss via hair and sweat) determined from long- term balance studies of four adult subjects ranged from a negative balance of 800 pg to a positive balance of 890 pg (Tipton et al. 1966, 1969). Based on data from these studies, Schroeder (1970) estimated that human daily intake from food (1,160 pg), water (80 pg), and air (10 pg) would be approximately 1,250p... 

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