Ammonia volatilization

Ammonia loss through volatilization to the atmosphere is a complex process mediated by a combination of physical, chemical, and biological factors. The exchange of ammonia between water column, soils, and the atmosphere plays an important role in wetland nitrogen cycle. However, the significance of this process is not well established. 

---

Only one study specifically compared volatilization losses between organic and conventional soil. Ammonia volatilization is mainly caused by animal manure rather than by N fertilizers (Kirchmann et al. 1998). 

Figure 3. The general nitrogen model for illustrating the bio geochemical cycling in Forest ecosystems. Explanations for the fluxes 1, ammonia volatilization 2, forest fertilization 3, N2-fixation 4, denitrification 5, nitrate respiration 6, nitrification 7, immobilization 8, mineralization 9, assimilatory and dissimilatory nitrate reduction to ammonium 10, leaching 11, plant uptake 12, deposition N input 13, residue composition, exudation 14, soil erosion 15, ammonium fixation and release by clay minerals 16, biomass combustion 17, forest harvesting 18, litterfall (Bashkin, 2002).

Ammonia Volatility down to PPM Levels pH vs. Composition and Effect of Electrolytes on Ammonia Volatility... 

Sodium Hydroxide and Sodium Acetate Effect on NH Volatility. Ammonia volatility measurements at various concentrations of so-dium hydroxide and sodium acetate at 80°C are given in Tables 23 and 24 respectively. Data on the effect of sodium hydroxide were measured using an ammonia probe from Orion Research Company. 

TABLE 24. Effect of Sodium Acetate Electrolyte on Ammonia Volatility at 80°C from Flow Cell Data... 

At the low ionic concentrations encountered in sour water strippers, the effect of dissolved ions is probably small. Thus at a 1% concentration of sodium acetate the volatility of ammonia only increases about 2.5% due to the salt. This is within the prediction accuracy of the ammonia volatility data and no correction is therefore required. However significant ionic effects could exist in the condenser where high concentrations of the ionic components could exist. 

Ammonia partial pressure data have been determined at concentrations from 10 ppm up to 5 wt % in water at temperatures of 80 and 120°C. The pH of NH3-H2S-CO2-H2O mixtures have also been measured at 25 and 80°C. Also the effects of sodium hydroxide and sodium acetate on ammonia volatility data have been measured at 80°C. Various conclusions made from the data are as follows. 

Wilson, G. M. Owens, R. S. Roe, M. W. "Sour Water Equilibria Ammonia Volatility Down to ppm Levels, Effect of Electrolytes... 

WHY A COMBINATION OF ODOUR—MEASUREMENT AND MEASUREMENT OF AMMONIA VOLATILIZATION ... 

In general I should like to plead for an integration of research on ammonia volatilization and odour research. In many cases odour control can be combined with reduction of ammonia losses. This is for instance the case with storage systems, ventilation systems, bio-filters or air scrubbers and injection of slurry. This double effect gives more possibilities to make the cost of control paying. 

HUTCHINSON, G.L. and VIETS, F.G. (1969). Nitrogen enrichment of surface water by absorption of ammonia volatilized from cattle feedlots. Science 166, 514-515. 

Ammonia volatilization from fertilizers is a function of the type of fertilizer, soil conditions, meteorological conditions-temperature, wind speed, precipita-tion-and fertilizer management. Table 8.6 shows the global use of nitrogenous fertilizers and the corresponding NH3 emissions based on empirical emission factors for different fertilizer types in temperate and tropical conditions (Bouwman... 

Fillery IRP, Simpson JR, De Datta SK. 1986. Contribution of ammonia volatilization to total nitrogen loss after applications of urea to wetland rice fields. Fertiliser Research 8 193-202. 

Freney JR, Trevitt ACF, De Datta SK, Obcemea WN, Real JG. 1990. The relative importance of denitrification and ammonia volatilization as loss processes in flooded rice in the Philippines. Mitteilungen der Deutschen Bodenkundlichen Gesellschaft 60, 211-216. 

Mikkelsen DS, De Datta SK, Obcemea WN. 1978. Ammonia volatilization losses from flooded rice soils. Soil Science Society of America Journal 42 725-730. 

Ammonia volatilization illustrates the behavior of inorganic chemicals in the subsurface under aerobic or anaerobic conditions. It is recognized that ammonia volatilization is affected by the time and depth of release, pH, temperature, and moisture content as well as by the cation exchange capacity. 

A special case is given by ammonia volatilization from flooded land surfaces, which involves a more complex pathway. This is because the kinetics and extent of the volatilization are affected by water quality, type of land, and biological and environmental factors. In this particular case, the rate of NH3 volatilization is mainly a function of ammonia concentration in the flooding water (Jayaweera and Mikkelsen 1991). 

So far, only kinetic isotope effects have been considered, but isotopic fractionations associated with equilibrium exchange reactions have been demonstrated for the common inorganic nitrogen compounds (Letolle 1980). Of special importance in this respect is the ammonia volatilization reaction ... 

This mechanism could be demonstrated via nitrogen elemental analysis of polymers and copolymers treated with amine acid salts and thermally cured (Table II and Experimental). In a control experiment, ammonium acetate was added In excess to a vinyl acetate/ethylene emulsion copolymer without amlnoplast crosslinker to confirm that essentially all of the ammonia volatilized from the unfunctlonallzed polymer during cure (much poorer volatilization was observed If NH4CI was used In place of NH4OAC). 

Experiment 1. Effect of Carbon Catalyst on Oxidation of Cobalt(ll) to Cobalt (III) and Formation of Ethylenediamine and Effect of Cobalt on Formation of Ethylenediamine. Carbon dioxide-free air was bubbled through the reaction mixture. Nine determinations each of the amounts of ammonia volatilized, the ethylenediamine concentration, and the cobalt (II) concentration were made over a period of 18 hours. The results are shown in Figure 1. 

The amount of ammonia volatilized was determined from the amount of standard sulfuric acid consumed in the traps. Ethylenediamine was determined by the salicylaldehyde method (14). The sample for cobalt(II) determination was made slightly acidic with hydrochloric acid immediately upon removal of the sample from the reaction flask, in order to prevent further oxidation of the cobalt (18). The carbon was removed by filtration, and the cobalt (II) concentration was determined spectrophotometrically as the cobalt-ammonium thiocyanate complex, (NH4)2Co(NCS)4 (28). 

Experiment 3. Rates of Formation of Ethylenediamine and Ammonia vs. Rate of Disappearance of Cobalt (II). Carbon dioxide-free air was bubbled through the solution. Ammonia, ethylenediamine, and cobalt (II) were determined periodically over a total reaction time of 5 hours. The results of this experiment are collected in Table I and plotted in Figure 3. The ammonia measured was actually the ammonia volatilized during the reaction, but it was calculated as moles per liter of solution in order to be consistent with the ethylenediamine and cobalt (II) results. 

Olesen JE, Sommer SG (1993) Modeling effects of wind-speed and surface cover on ammonia volatilization from stored pig slurry. Atmos Environ Part A 27 2567-2574... 

Genermont S, Cellier P (1997) A mechanistic model for estimating ammonia volatilization from slurry applied to bare soil. Agr Forest Meteorol 88 145-167... 

Reddy et al. (1979a,b) Donigan and Crawford (1976) model extended to handle animal waste loadings. Modified mineralization simulation with considerations for potentially mineralized nitrogen and short-term rate kinetics. Added ammonia volatilization from animal wastes that is dependent on temperature, air flow rate, and CEC. Mineralization and volatilization validated with laboratory data. 

Reddy, K. R., Khaleel, R., Overcash, M. R., and Westerman, P. W. (1979b). A nonpoint source model for land areas receiving animal wastes. II. Ammonia volatilization. Trans. ASAE 22, 1398-1405. 

Volatilization of ammonia from aqueous solutions. When an aqueous solution of ammonia (ammonium hydroxide) is warmed, some of the dissolved ammonia volatilizes in the gaseous form. This result is to be anticipated in light of the manner in which the solubility of gases in liquids is generally influenced by an increase in temperature. In the use of this method, the quantity of heat supplied should be such that a minimum quantity of water is vaporized. 

Hexamethyldisilazane is a nonmo-tile liquid can be hydrolysed with water, releasing ammonia. Volatile, flammable. MAC=5 mg/m3. 

AN EQUILIBRIUM-BASED MODEL FOR PREDICTING POTENTIAL AMMONIA VOLATILIZATION FROM SOIL... 

Avnimelech, Y. and M. Laher. 1977. Ammonia volatilization from soils Equilibrium considerations. Soil Sci. Am. J. 41 1080-1084. 

Brock, B. R. and D. E. Kissel, Eds. 1988. Ammonia Volatilization from Urea Fertilizers. Tennessee Valley Authority, Muscle Shoals, AL. 

Ferguson, R. B., D. E. Kissel, J. K. Koelliker, and W. Basel. 1984. Ammonia volatilization from surface-applied urea Effects of hydrogen ion buffering capacity. Soil Sci. Soc. Am. J. 48 578-582. 

Urea undergoes microbial hydrolysis catalyzed by urease, leading to loss of as much as 30% of its nitrogen from ammonia volatilization. The reduced nitrogen availability in the soils appears particularly when urea is surface broadcast on soils. The factors that influence ammonia volatilization include levels of urease activity, moisture availability, nitrification rate, and soil texture (Bernard et al., 2009). 

Several alternatives are used to reduce ammonia elimination. Applied in relatively small quantities, urease inhibitors such as A-(n-butyl) thiophosphoric acid triamide reduce the rate of microbial hydrolysis of urea and increase its efficiency as a fertilizer (Manahan, 2005). Ammonia volatilization could also be reduced using a mixture of urea with tropical peat soil or free humic substances, such as humic and fulvic acids, isolated from peat soils (Bernard et al., 2009). Another application of green technologies is the use of thermal polyaspartate, a product formed by the condensation and base treatment of a natural compound, aspartic acid. This has been found to be effective in stimulating plant uptake of fertilizer thus reducing the amount of fertilizer required (Manahan, 2005). 

---