Bradley said he believed Monsanto was not willing to discuss volatilization.
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The EPA's new limits focus on the application issues and do not address volatilization, herbicide experts and farmers said.
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Specialists, though, say the weed killer is risky because they can vaporize and drift across fields, a process called volatilization.
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Norsworthy, a University of Arkansas professor, has declined an invitation to speak about volatilization at Monsanto's meeting, according to the university.
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Monsanto recently upset U.S. weed scientists by questioning the objectivity of two Arkansas experts, Jason Norsworthy and Ford Baldwin, who said dicamba had problems with volatilization.
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"Anybody that sprays it, you have issues with the volatilization," CEO Sonny Beck said in an interview on Wednesday, referring to the chemical vaporizing and drifting.
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Farmers and weed experts say the products harm crops that cannot resist dicamba because the herbicides evaporate and drift away from where they are applied, a process known as volatilization.
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Farmers also will not be able to apply dicamba-based herbicides if temperatures top 85 degrees Fahrenheit because research shows high temperatures increase crop damage from volatilization, according to Minnesota.
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The company plans to present data at the summit that it says show user error was behind the damage, contrary to academics' findings that dicamba products can vaporize and move off target under certain conditions in a process known as volatilization.
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1,2-Difluoroethane can enter the environment various ways. One way is through volatilization from rivers and lakes. Henry’s Law estimates that the volatilization half life from a model river is about 2.4 hours and 3.2 days from a model lake. When 1,2-difluoroethane is released to the environment, it will end up in the atmosphere.
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2-methypyridine and 4-methypyridine are more readily degraded and exhibit less volatilization loss from environmental samples than does 3-methypyridine.
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Ammonia volatilization reduces the economic efficiency of agricultural cropping systems. Either yield will be reduced or additional costs will be incurred from additional nitrogen fertilizer. The amount of ammonia volatilization depends on several environmental factors, including temperature, pH, and the soil water content. Additionally, the amount of surface residue and time between urea application and precipitation are also critical.
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Volatilization methods can be either direct or indirect. Water eliminated in a quantitative manner from many inorganic substances by ignition is an example of a direct determination. It is collected on a solid desiccant and its mass determined by the gain in mass of the desiccant. Another direct volatilization method involves carbonates which generally decompose to release carbon dioxide when acids are used.
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Reactive flash volatilization (RFV) is a chemical process that rapidly converts nonvolatile solids and liquids to volatile compounds by thermal decomposition for integration with catalytic chemistries.
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Generally speaking, volatilization will be lower when urea is applied during the wetter and cooler conditions that generally occur in early spring (March and April). However, drying surface soil and rising temperatures as spring progresses increases the probability of ammonia volatilization. Ideally, a manager should attempt to apply nitrogen immediately before a moderate rain event (0.1 inch), allowing urea to dissolve and move into the soil. However, this is not always possible.
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This technique may be limited to screening libraries of size of less than around 106. The successful cleavage of X-gal also creates a noticeably foul odor due to the volatilization of indole.
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However, the overall distribution also suggested that the PAHs in London soils had undergone weathering and been modified by a variety of pre-and post-depositional processes such as volatilization and microbial biodegradation.
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Most of the methyl chloride present in the environment ends up being released to the atmosphere. After being released into the air, the life of this substance in the atmosphere varies from one to three years. On the other hand, when the methyl chloride emitted is released to water, it will be rapidly lost by volatilization. The [half-life] of this substance in terms of volatilization in the river, lagoon and lake is 2.1 h, 25 h and 18 days, respectively.
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Environmental Toxicology and Chemistry. 5:503-509. Estimated time for complete degradation was > 30 days. 2-Chloropyridine exhibits extensive volatilization losses from water, less so when present in soil.Sims, G. K. and L.E. Sommers. 1985.
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Encapsulation helps reduce volatility and therefore reduces off-target damage to sensitive plants.Mervosh, T. L., E.W. Stoller, T.R. Ellsworth, and G.K. Sims. 1995. Effects of starch encapsulation on clomazone and atrazine movement in soil and clomazone volatilization.
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Paul Dauenhauer was born in 1980 in Texas, USA, and was raised in Wisconsin Rapids, WI, attending Lincoln High School. He received his bachelor's degree in chemical engineering and chemistry at the University of Wisconsin, Madison in 2004. Working under the supervision of Lanny Schmidt at the University of Minnesota, Dauenhauer received his Ph.D. in chemical engineering in 2008 from the Department of Chemical Engineering & Materials Science. His dissertation described the development of reactive flash volatilization and was titled "Millisecond autothermal catalytic reforming of carbohydrates for synthetic fuels by reactive flash volatilization".
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The problem may be as simple as masking the taste or odor of the core, or as complex as increasing the selectivity of an adsorption or extraction process. In environmental science, a pesticide may be microencapsulated to minimize leaching or volatilization risks.
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Calcination reactions usually take place at or above the thermal decomposition temperature (for decomposition and volatilization reactions) or the transition temperature (for phase transitions). This temperature is usually defined as the temperature at which the standard Gibbs free energy for a particular calcination reaction is equal to zero.
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ISSN 1064-3389 The urea in urine naturally converts into ammonia through a process known as ammonia volatilization from urea. This process, which can take between 5 weeks to 6 months, increases the pH of the liquid to 9, thus sterilizing it.Sánchez, Henrique (2015). Lactuca sativa production in an anthroponics system.
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Pickleweed is used in Phytoextraction, it is highly effective at removing selenium from soil, which is absorbed by the plant and then released into the atmosphere to be dispersed by prevailing winds. Pickleweed (Salicornia bigelovii) has been found to have average volatilization rates 10-100 times higher than other species.
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Chlorides are likely to be easier than fluorides to later convert back to other compounds, such as oxides. Chlorides remaining after volatilization may also be separated by solubility in water. Chlorides of alkaline elements like americium, curium, lanthanides, strontium, caesium are more soluble than those of uranium, neptunium, plutonium, and zirconium.
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Urea as a Source of Fertilizer Nitrogen for Crops in Kentucky. Extension Report. Lexington, KY: University of Kentucky College of Agriculture, 1978. It is important that there is adequate moisture because up to thirty percent of the available nitrogen can be lost through atmospheric volatilization within seventy-two hours of application.
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Soils that have high organic matter content also tend to have higher urease concentrations. More urease results in greater hydrolysis of urea and ammonia volatilization, particularly if urea fails to move into the soil.Torello W.A. and Wehner D.J.. “Urease Activity in a Kentucky Bluegrass Turf.” Agronomy Journal (1983): 654-656.
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This refractory layer needs to be replaced from time to time. Movement of the cylinder on its axis facilitates movement of waste. In the primary chamber, there is conversion of solid fraction to gases, through volatilization, destructive distillation and partial combustion reactions. The secondary chamber is necessary to complete gas phase combustion reactions.
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Studies with several leaf types (bean - lettuce) showed that residues diminished rapidly on both types of surfaces. The primary mechanism by which leptophos was lost was presumed to be by volatilization. Qualitatively, leptophos was metabolized to products similar to those found with the mouse. Phenyl phosphonate derivatives were also recovered from plant surfaces.
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The use of inhibitors also decreases the localized zones of high pH common with untreated urea.Watson, C.J., et al. "Rate and mode of application of the urease inhibitor N-(n-butyl) thiophosphoric triamide on ammonia volatilization from surface-applied urea." Soil Use and Management, British Society of Soil Science (2008): 1-7.
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The soil's pH also has a strong effect on the amount of volatilization. Specifically, highly alkaline soils (pH~8.2 or higher) have proven to increase urea hydrolysis. One study has shown complete hydrolysis of urea within two days of application on such soils. In acidic soils (pH 5.2) the urea took twice as long to hydrolyze.
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PennWell Corporation. A wide range of wastewater treatment techniques are known, which includes biological processes for nitrification, denitrification and phosphorus removal, as well as a range of physico-chemical processes that require chemical addition. The commonly used physico-chemical treatment processes are filtration, air stripping, ion exchange, chemical precipitation, chemical oxidation, carbon adsorption, ultrafiltration (UF), reverse osmosis (RO), electrodialysis, volatilization, and gas stripping.
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Coal tar is an aromatic hydrocarbon and a by- product from the coking process of the coal industry. It is historically in abundance where coal is used in steel manufacturing. It ages very slowly through volatilization and is an excellent waterproofing and oil resistant product. Roofs are covered by heating the coal tar and applying it between layers of tar paper.
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PCP is released directly into the atmosphere via volatilization from treated wood products and during production. Finally, releases to the soil can be by leaching from treated wood products, atmospheric deposition in precipitation (such as rain and snow), spills at industrial facilities, and at hazardous waste sites. After PCP is released into the atmosphere, it decomposes through photolysis. The main biodegradative pathway for PCP is reductive dehalogenation.
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For steel, the first step will be the volatilization of the inhibitor into the airspace. This may entail simple evolution of the molecule or the chemical may disassociate first and then volatilize. (15) The molecules will then diffuse through the enclosed airspace until some of the molecules will reach the metallic surface to be protected. There are two likely paths once the molecules reach the metallic surface.
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Hummel and Waddington, 2001, found that a slow release nitrogen fertilizer application could provide nitrogen over a long duration and keep nitrogen leaching and volatilization losses to a minimum. A further study demonstrated that after fertilizer application, nitrogen losses exceeded EPA limits. Photoperiod (the length of daylight) affects overall plant uptake. When the length of daylight gets shorter, grass undergoes less photosynthesis and uptakes less nitrogen.
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Volatilization is the process whereby a dissolved sample is vaporised. In atomic spectroscopy this is usually a two-step process. The analyte is turned into small droplets in a nebuliser which are entrained in a gas flow which is in turn volatilised in a high temperature flame in the case of AAS or volatilised in a gas plasma torch in the case of ICP spectroscopy.
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The astatine-containing cyclotron target is heated to a temperature of around 650 °C. The astatine volatilizes and is condensed in (typically) a cold trap. Higher temperatures of up to around 850 °C may increase the yield, at the risk of bismuth contamination from concurrent volatilization. Redistilling the condensate may be required to minimize the presence of bismuth (as bismuth can interfere with astatine labeling reactions).
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The three type of medical waste incinerators are controlled air, excess air, and rotary kiln. Controlled air is also known as starved-air incineration, two-stage incineration, or modular combustion. This is the process of which waste is fed to a combustion chamber and combustion air begins to dry and facilitates volatilization of the waste. As a result, carbon dioxide and other excess gases are released into the atmosphere.
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Volatilization is the primary removal mechanism on most ERH sites. However, ERH can also be used to enhance other processes, some naturally occurring, to reduce the cost for treatment of a plume. ERH can be used to provide controlled low temperature heating for projects with remediation processes that do not involve steam stripping. "Low temperature heating" refers to the targeting of a subsurface temperature that is less than the boiling point of water.
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Lanny D. Schmidt (May 6, 1938 – March 27, 2020) was an American chemist, inventor, author, and Regents Professor of Chemical Engineering and Materials Science at the University of Minnesota. He is well known for his extensive work in surface science, detailed chemistry (microkinetics), chemical reaction engineering, catalysis, and renewable energy. He is also well known for mentoring over a hundred graduate students and his work on millisecond reactors and reactive flash volatilization.
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In volatilization methods, removal of the analyte involves separation by heating or chemically decomposing a volatile sample at a suitable temperature. In other words, thermal or chemical energy is used to precipitate a volatile species. For example, the water content of a compound can be determined by vaporizing the water using thermal energy (heat). Heat can also be used, if oxygen is present, for combustion to isolate the suspect species and obtain the desired results.
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During summer, urea is often spread just before or during rain to minimize losses from volatilization (a process wherein nitrogen is lost to the atmosphere as ammonia gas). Because of the high nitrogen concentration in urea, it is very important to achieve an even spread. The application equipment must be correctly calibrated and properly used. Drilling must not occur on contact with or close to seed, due to the risk of germination damage.
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Natural sources of mercury released to the atmosphere include volcanoes, forest fires, volatilization from the ocean and weathering of mercury-bearing rocks.Tewalt, S. J.; Bragg, L. J.; Finkelman, R. B., 2005, Mercury in U.S. coal -- Abundance, distribution, and modes of occurrence, U.S. Geological Survey Fact Sheet 095-01. Access-date=January 12, 2006. Anthropogenic sources of mercury include the burning of wastes containing inorganic mercury and from the burning of fossil fuels, particularly coal.
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Picolines exhibit greater volatility and are more slowly degraded than their carboxylic acid counterparts. Volatilization is much less extensive in soil than water, owing to sorption of the compounds to soil clays and organic matter. Picoline degradation appears to be mediated primarily by bacteria, with the majority of isolates belonging to the Actinobacteria. 3-Methylpyridine degrades more slowly than the other two isomers, likely due to the impact of resonance in the heterocyclic ring.
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The popularity of OPEs as flame retardants came as a substitution for the highly regulated brominated flame retardants. The low cost of production and compatibility to different polymers made OPEs to be widely used in different industries including textile, furniture, electronics as plasticizers and flame retardants. These compounds are added to the final product physically rather than by chemical bond. Due to this OPEs leak into the environment more readily through volatilization, leaching, as well as abrasion.
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On the other hand, because of its high adsorption capacity, biochar may reduce the efficacy of soil applied pesticides that are used for weed and pest control.Graber, E.R., Tsechansky, L., Gerstl, Z., Lew, B. (2011) High surface area biochar negatively impacts herbicide efficacy. Plant and Soil, 353:95-106Graber, E.R., Tsechansky, L., Khanukov, J., Oka, Y. (2011) Sorption, volatilization and efficacy of the fumigant 1,3-dichloropropene in a biochar-amended soil. Soil Science Society of America Journal.
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Some samples contained a small amount of metallic melt (less than 0.5%), composed of silver and indium (from the control rods). A secondary phase composed of chromium(III) oxide was found in one of the samples. Some metallic inclusions contained silver but not indium, suggesting a sufficiently high temperature to cause volatilization of both cadmium and indium. Almost all metallic components, with the exception of silver, were fully oxidized; however even silver was oxidized in some regions.
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When compounds in this oxidation state are formed, the outer shell s electrons are lost, yielding a bare zinc ion with the electronic configuration [Ar]3d10. In aqueous solution an octahedral complex, is the predominant species. The volatilization of zinc in combination with zinc chloride at temperatures above 285 °C indicates the formation of , a zinc compound with a +1 oxidation state. No compounds of zinc in oxidation states other than +1 or +2 are known.
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Thermal decomposition of concrete produces water vapor and carbon dioxide, which may further react with the metals in the melt, oxidizing the metals, and reducing the gases to hydrogen and carbon monoxide. The decomposition of the concrete and volatilization of its alkali components is an endothermic process. Aerosols released during this phase are primarily based on concrete-originating silicon compounds; otherwise volatile elements, for example, caesium, can be bound in nonvolatile insoluble silicates. Several reactions occur between the concrete and the corium melt.
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The two most common gravimetric methods using volatilization are those for water and carbon dioxide. An example of this method is the isolation of sodium hydrogen bicarbonate (the main ingredient in most antacid tablets) from a mixture of carbonate and bicarbonate. The total amount of this analyte, in whatever form, is obtained by addition of an excess of dilute sulfuric acid to the analyte in solution. In this reaction, nitrogen gas is introduced through a tube into the flask which contains the solution.
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New York: Prentice Hall, 2001. Additionally, the formation of the hydroxide ion may cause soils around the applied urea particle to have a pH around 9.0 which increases ammonia volatilization. This area is also highly toxic due to elevated ammonia concentration for several hours so it is recommended that urea based fertilizers not be applied or banded with planted seed at a rate that exceeds 10–20 kg/ha, depending on the crop species.Wells, K.L., L.W. Murdock and H.F. Miller.
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Triphenyl phosphate has been detected in the environment. Other triaryl phosphates have been known to enter aquatic environments through volatilization and leaching from plastics, through hydraulic fluid leakages, and, to a lesser degree, through manufacturing processes. TPhP, in particular, has been found to enter the environment through industrial use, as in the manufacturing process, and through indoor use, for example through paints and electronic equipment. As with many other phosphorus-containing flame retardants, TPhP has been found widely in sediment, soil, indoor dust, and air.
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These new paints are widely available and meet or exceed the old high-VOC products in performance and cost-effectiveness while having significantly less impact on human and environmental health. A polychlorinated biphenyl (PCB) was reported (published in 2009) in air samples collected in Chicago, Philadelphia, the Arctic, and several sites around the Great Lakes. PCB is a global pollutant and was measured in the wastewater effluent from paint production. The widespread distribution of PCB suggests volatilization of this compound from surfaces, roofs etc.
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Nitrogen is a limiting nutrient for growth in many soda lakes, making the internal nitrogen cycle very important for their ecological functioning. One possible source of bio-available nitrogen is diazotrophic cyanobacteria, which can fix nitrogen from the atmosphere during photosynthesis. However, many of the dominant cyanobacteria found in soda lakes such as Arthrospira are probably not able to fix nitrogen. Ammonia, a nitrogen-containing waste product from degradation of dead cells, can be lost from soda lakes through volatilization because of the high pH.
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A few other elements also form similarly volatile hexafluorides, pentafluorides, or heptafluorides. The volatile fluorides can be separated from excess fluorine by condensation, then separated from each other by fractional distillation or selective reduction. Uranium hexafluoride and technetium hexafluoride have very similar boiling points and vapor pressures, which makes complete separation more difficult. Many of the fission products volatilized are the same ones volatilized in non-fluorinated, higher-temperature volatilization, such as iodine, tellurium and molybdenum; notable differences are that technetium is volatilized, but caesium is not.
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Power density increased with the number of batteries in the system. Volatilization of ammonia from the spent anolyte by heating (simulating distillation), and re-addition of this ammonia to the spent catholyte chamber with subsequent operation of this chamber as the anode (to regenerate copper on the other electrode), produced a maximum power density of 60 ± 3 W m−2, with an average discharge energy efficiency of 29% (electrical energy captured versus chemical energy in the starting solutions). An acid added to the catholyte increased power 126 ± 5 W m−2.
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In maintenance and repair work, the process is commonly used to repair tools and dies, especially components made of aluminum and magnesium. Because the weld metal is not transferred directly across the electric arc like most open arc welding processes, a vast assortment of welding filler metal is available to the welding engineer. In fact, no other welding process permits the welding of so many alloys in so many product configurations. Filler metal alloys, such as elemental aluminum and chromium, can be lost through the electric arc from volatilization.
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The ecological complexity of marine life in this zone has been diminishing as a consequence. As well as bringing nitrogen into agroecosystems through biological nitrogen fixation, types of cover crops known as "catch crops" are used to retain and recycle soil nitrogen already present. The catch crops take up surplus nitrogen remaining from fertilization of the previous crop, preventing it from being lost through leaching, or gaseous denitrification or volatilization. Catch crops are typically fast-growing annual cereal species adapted to scavenge available nitrogen efficiently from the soil.
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Pigs kept on deep-litter material Deep litter is an animal housing system, based on the repeated spreading of straw or sawdust material in indoor booths. An initial layer of litter is spread for the animals to use for bedding material and to defecate in, and as the litter is soiled, new layers of litter are continuously added by the farmer. In this fashion, a deep litter bedding can build up to depths of 1–2 meters.Groenestein & Van Faassen, 1996 - Volatilization of Ammonia, Nitrous Oxide and Nitric Oxide in Deep-litter Systems for Fattening Pigs.
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For instance, it has been shown to accumulate in the air if there is a meteorological inversion and little wind. Because atmospheric radon concentrations are very low, radon-rich water exposed to air continually loses radon by volatilization. Hence, ground water generally has higher concentrations of 222Rn than surface water, because the radon is continuously produced by radioactive decay of 226Ra present in rocks. Likewise, the saturated zone of a soil frequently has a higher radon content than the unsaturated zone because of diffusional losses to the atmosphere.
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This is an example of allelopathy, which is the release of chemicals from plant parts by leaching, root exudation, volatilization, residue decomposition and other processes. Allelopathy can have beneficial, harmful, or neutral effects on surrounding organisms. Some allelochemicals even have selective effects on surrounding organisms; for example, the tree species Leucaena leucocephala exudes a chemical that inhibits the growth of other plants but not those of its own species, and thus can affect the distribution of specific rival species. Allelopathy usually results in uniform distributions, and its potential to suppress weeds is being researched.
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Contaminates are then broken down and the fragments are then subsequently transformed and volatilized into the atmosphere. Phytovolatilization is the removal of substances from soil or water with release into the air, sometimes as a result of phytotransformation to more volatile and/or less polluting substances. In this process, contaminants are taken up by the plant and through transpiration, evaporate into the atmosphere. This is the most studied form of phytovolatilization, where volatilization occurs at the stem and leaves of the plant, however indirect phytovolatilization occurs when contaminants are volatilized from the root zone.
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Selenium can be removed from the ecosystem and bound in sediment through natural processes of chemical and microbial reduction of the selenate form to the selenite form. The reduction is followed by adsorption to clay, reaction with iron species, and coprecipitation or settling. After selenium is in the sediment, other chemical and microbial reduction may occur, causing insoluble organic, mineral, elemental, or adsorbed selenium. Some organic forms may be released into the atmosphere from volatilization by chemical or microbial activity in the water and sediment or by direct release from plants.
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Monsanto has requested approval for a stacked strain that is tolerant of both glyphosate and dicamba. The request includes plans for avoiding herbicide drift to other crops. Significant damage to other non- resistant crops occurred from dicamba formulations intended to reduce volatilization drifting when sprayed on resistant soybeans in 2017. The newer dicamba formulation labels specify to not spray when average wind speeds are above to avoid particle drift, average wind speeds below to avoid temperature inversions, and rain or high temperatures are in the next day forecast.
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Polyethylene waxes produced by means of degradation or recovery from polyethylene resin streams contain very low molecular weight materials that must be removed to prevent volatilization and potential fire hazards during use. Polyethylene waxes manufactured by this method are usually stripped of low molecular weight fractions to yield a flash point > 500°F(> 260°C). Many polyethylene resin plants produce a low molecular weight stream often referred to as Low Polymer Wax (LPW). LPW is unrefined and contains volatile oligomers, corrosive catalyst and may contain other foreign material and water.
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Space satellites are under such conditions where liquid lubrication is useless as many liquid lubricants become prone to volatilization due to extremely low pressures - from nearly 100 kPa at launch, to 10 nPa in orbit. With the help of chameleon coating, the life expectancy of satellites range from 15 to about 30 years. Chameleon coatings are also often used on hypersonic and reusable launch vehicles that require lubrication in ambient atmosphere, vacuum (space), and during re-entry (high temperature). A typical multilayer coating may use a molybdenum disulfide or diamond-like carbon for low friction at ambient conditions.
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Waste-water nitrate has higher concentrations of 15N than the nitrate that is found in natural soils in near shore zones. For bacteria, it is more convenient for them to uptake 14N as opposed to 15N because it is a lighter element and easier to metabolize. Thus, due to bacteria's preference when performing biogeochemical processes such as denitrification and volatilization of ammonia, 14N is removed from the water at a faster rate than 15N, resulting in more 15N entering the aquifer. 15N is roughly 10-20‰ as opposed to the natural 15N values of 2-8‰.
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A conveyor furnace uses a flexible metal belt to convey soil through the primary heating chamber. A one-inch-deep layer of soil is spread evenly over the belt. As the belt moves through the system, soil agitators lift the belt and turn the soil to enhance heat transfer and volatilization of organics. The conveyor furnace can heat soils to temperatures from 300 to 800 degrees F. At the higher temperature range, the conveyor furnace is more effective in treating some heavier petroleum hydrocarbons than are oil- or steam-heated thermal screws, asphalt plant aggregate dryers, and carbon steel rotary dryers.
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Low-temperature thermal desorption (LTTD), also known as low-temperature thermal volatilization, thermal stripping, and soil roasting, is an ex-situ remedial technology that uses heat to physically separate petroleum hydrocarbons from excavated soils. Thermal desorbers are designed to heat soils to temperatures sufficient to cause constituents to volatilize and desorb (physically separate) from the soil. Although they are not designed to decompose organic constituents, thermal desorbers can, depending upon the specific organics present and the temperature of the desorber system, cause some organic constituents to completely or partially decompose. The vaporized hydrocarbons are generally treated in a secondary treatment unit (e.g.
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Schlesinger served as the co-principal investigator for the Jornada Basin Long Term Ecological Research (LTER) located in the Chihuahuan Desert in southern New Mexico. Research projects mainly focus on inorganic fluxes, including studies of ammonia volatilization from soils, hydrology natural runoff plots and transect soil water content. He has also worked extensively in arid ecosystems and landscapes, studying responses to resource redistribution and global change, which can lead to soil degradation and regional desertification. Schlesinger postulated that the patchy distribution of vegetation in desert regions controls many aspects of soil fertility and the response of deserts to overgrazing and climate change.
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In Milwaukee, an atmospheric concentration of 1.9 ng/m3 has been measured, and this source alone was estimated to account for 120 kg/year of PCBs entering Lake Michigan. In 2008, concentrations as high as 35 ng/m3, 10 times higher than the EPA guideline limit of 3.4 ng/m3, have been documented inside some houses in the U.S. Volatilization of PCBs in soil was thought to be the primary source of PCBs in the atmosphere, but research suggests ventilation of PCB-contaminated indoor air from buildings is the primary source of PCB contamination in the atmosphere.
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500px Reactive flash volatilization of solid particles composed of cellulose, starch, lignin, Quaking Aspen (Populus tremuloides) wood chips, and polyethylene was demonstrated in 2007 in the scientific journal Angewandte Chemie. Particles of cellulose were completely converted to syngas (H2 and CO) and combustion products (H2O and CO2) in as little as 30 milliseconds. Catalytic reforming of all materials occurred without the requirement of an external heat source while operating at 500–900 °C. Under optimal conditions, 50% of all atomic hydrogen and 50% of all atomic carbon can be converted to molecular H2 and carbon monoxide in as little time as 30 milliseconds.
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Reaction chemistry was demonstrated on both a Rh-Ce/alumina catalyst and a Ni- Ce/alumina catalyst. A publication in the scientific journal Green Chemistry demonstrated that the process of reactive flash volatilization can be considered a combination of several other global chemistries occurring through thermal and chemical integration. As shown in the diagram at the right, the initial pyrolysis chemistry occurs when the biomass particle (green) physically contacts the hot catalyst (orange). Volatile organic compounds (VOCs) flow into the catalyst with oxygen, adsorb on Rh atoms, and react to form combustion products (H2O and CO2) and syngas (H2 and CO).
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Natural radon concentrations in the Earth's atmosphere are so low that radon- rich water in contact with the atmosphere will continually lose radon by volatilization. Hence, ground water has a higher concentration of 222Rn than surface water, because radon is continuously produced by radioactive decay of 226Ra present in rocks. Likewise, the saturated zone of a soil frequently has a higher radon content than the unsaturated zone because of diffusional losses to the atmosphere. In 1971, Apollo 15 passed above the Aristarchus plateau on the Moon, and detected a significant rise in alpha particles thought to be caused by the decay of 222Rn.
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Her current research focuses on developing and improving trace gas flux measurement techniques to quantify greenhouse gas emissions (particularly N2O, CH4, and CO2) and other airborne contaminants, such as ammonia and particulate matter. She did pioneer work on the relaxed eddy accumulation technique to measure trace gas fluxes. She has contributed to international efforts for verifying process-based models for greenhouse gas emissions and ammonia volatilization from agricultural sources, and for assimilating biophysical descriptors using remote sensing data in soil and crop growth models. In her research, she evaluates the impact of beneficial management practices on air quality and the impact of climate variations on the sustainability of crop production.
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A thermal blanket is a device used in thermal desorption to clean soil contamination. The primary function of a thermal blanket is to heat the soil to the boiling point of the contaminants (usually 100 to 325 °C and as high as 900 °C) so that they break down. A vacuum pulls the resulting gas (along with volatilized contaminants) into a separate air cleaner that may use various methods, such as carbon filters and high-heat ovens, to completely destroy the contaminants. Aside from evaporation and volatilization, the contaminants may also be removed from the soil through other mechanisms such as steam distillation, pyrolysis, oxidation, and other chemical reactions.
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Air sparging, also known as in situ air stripping and in situ volatilization is an in situ remediation technique, used for the treatment of saturated soils and groundwater contaminated by volatile organic compounds (VOCs) like petroleum hydrocarbons which is a widespread problem for the ground water and soil health. The vapor extraction has manifested itself into becoming very successful and practical when it comes to disposing of VOCs. It was used as a new development when it came to saturated zone remediation when using air sparging. Being that the act of it was to inject a hydrocarbon-free gaseous medium into the ground where contamination was found.
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As noted above, treating metals-containing sediments with HCl liberates metal ions into the acid solution that were previously bound up with AVS. After treatment these are present in solution, along with any metals that were initially unbound to AVS (due to insufficient AVS in the sediment to "mop up" all the metal ions). The concentrations of metals in the acid solution can be measured by a number of analytical chemistry methods, including atomic emission spectrometry, atomic absorption spectrometry (AAS), or mass spectrometry. These are known as "simultaneously extracted metals" because they are the metals liberated from the sediment while the volatilization of sulfide is occurring.
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Mercury is a health hazard, especially when in gas form. To remove this hazard, before smelting, gold precipitates from electrowinning or Merrill- Crowe processes are usually heated in a retort to recover any mercury present, that would otherwise cause health and environmental problems due to its release (volatilization) during smelting. The mercury present is not usually from the mercury amalgamation process that is no longer used by formal gold mining companies, but from mercury in the ore that has followed gold through the leaching and precipitation processes. In the event that there are high levels of copper present, leaching of the precipitate using nitric or sulfuric acids may be required.
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For microscale particles, as particle size decreases and the specific surface area increases, the explosion severity increases. However, for dusts of organic materials such as coal, flour, methylcellulose, and polyethylene, severity ceases to increase as the particle size is reduced below ∼50 μm. This is because decreasing particle size primarily increases the volatilization rate, which becomes rapid enough that that gas phase combustion becomes the rate limiting step, and further decrease in particle size will not increase the overall combustion rate. While the minimum explosion concentration does not vary significantly with nanoparticle size, the minimum ignition energy and temperature have been found to decrease with particle size.
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A simple wildfire propagation model On a molecular scale, there are two main competing reaction processes involved in the degradation of cellulose, or wood fuels, in wildfires. When there is a low amount of moisture in a cellulose fiber, volatilization of the fuel occurs; this process will generate intermediate gaseous products that will ultimately be the source of combustion. When moisture is present—or when enough heat is being carried away from the fiber, charring occurs. The chemical kinetics of both reactions indicate that there is a point at which the level of moisture is low enough—and/or heating rates high enough—for combustion processes become self-sufficient.
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These smaller organic molecules begin to dissolve and move to the liquid phase, followed by hydrolysis of these organic molecules, and the hydrolyzed compounds then undergo transformation and volatilization as carbon dioxide (CO2) and methane (CH4), with rest of the waste remaining in solid and liquid phases. During the early phases, little material volume reaches the leachate, as the biodegradable organic matter of the waste undergoes a rapid decrease in volume. Meanwhile, the leachate's chemical oxygen demand increases with increasing concentrations of the more recalcitrant compounds compared to the more reactive compounds in the leachate. Successful conversion and stabilization of the waste depends on how well microbial populations function in syntrophy, i.e.
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The oxide layer produces heat primarily by decay heat, while the principal heat source in the metal layer is exothermic reaction with the water released from the concrete. Decomposition of concrete and volatilization of the alkali metal compounds consumes a substantial amount of heat. The fast erosion phase of the concrete basemat lasts for about an hour and progresses to about one meter in depth, then slows to several centimeters per hour, and stops completely when the melt cools below the decomposition temperature of concrete (about ). Complete melt-through can occur in several days even through several meters of concrete; the corium then penetrates several meters into the underlying soil, spreads around, cools and solidifies.
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Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte (the ion being analyzed) based on its mass. The principle of this type of analysis is that once an ion's mass has been determined as a unique compound, that known measurement can then be used to determine the same analyte's mass in a mixture, as long as the relative quantities of the other constituents are known. The four main types of this method of analysis are precipitation, volatilization, electro- analytical and miscellaneous physical method. The methods involve changing the phase of the analyte to separate it in its pure form from the original mixture and are quantitative measurements.
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Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication, in a manner not intended by the manufacturer. They are inhaled at room temperature through volatilization (in the case of gasoline or acetone) or from a pressurized container (e.g., nitrous oxide or butane), and do not include drugs that are sniffed after burning or heating. For example, amyl nitrite (poppers), nitrous oxide and toluene – a solvent widely used in contact cement, permanent markers, and certain types of glue – are considered inhalants, but smoking tobacco, cannabis, and crack are not, even though these drugs are inhaled as smoke.
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Fires can affect soils through heating and combustion processes. Depending on the temperatures of the soils caused by the combustion processes, different effects will happen- from evaporation of water at the lower temperature ranges, to the combustion of soil organic matter and formation of pyrogenic organic matter, otherwise known as charcoal. Fires can cause changes in soil nutrients through a variety of mechanisms, which include oxidation, volatilization, erosion, and leaching by water, but the event must usually be of high temperatures in order of significant loss of nutrients to occur. However, quantity of nutrients available in soils are usually increased due to the ash that is generated, and this is made quickly available, as opposed to the slow release of nutrients by decomposition.
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Degradation of DDT to form DDE (by elimination of HCl, left) and DDD (by reductive dechlorination, right) DDT is a persistent organic pollutant that is readily adsorbed to soils and sediments, which can act both as sinks and as long-term sources of exposure affecting organisms. Depending on conditions, its soil half-life can range from 22 days to 30 years. Routes of loss and degradation include runoff, volatilization, photolysis and aerobic and anaerobic biodegradation. Due to hydrophobic properties, in aquatic ecosystems DDT and its metabolites are absorbed by aquatic organisms and adsorbed on suspended particles, leaving little DDT dissolved in the water (however, its half-life in aquatic environments is listed by the National Pesticide Information Center as 150 years).
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With a high Koc of 3900, DCPA is presumably immobile in soil, and thus may strongly attach to inorganic material in soil and other environments In addition, its breakdown products, TPA (Tetrachloroterephthalic acid) and MTP (Monomethyl tetrachloroterephthalic acid), enter the environment after being formed through various processes. Studies have shown that DCPA can partially degrade through volatilization, as well as via photodegradation, but biodegradation is the primary route of DCPA degradation leading to MTP and TPA. Environmental Protection Agency testing in New York showed "measurable residues of DCPA and degradates" on land that had endured five years of treatment with DCPA, followed by three years of no treatment. DCPA is also prevalent in water and bioconcentration is seen in aquatic animals.
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VCl3 is prepared by heating VCl4 at 160–170 °C under a flowing stream of inert gas, which sweeps out the Cl2. The bright red liquid converts to a purple solid. Heating of VCl3 decomposes with volatilization of VCl4, leaving VCl2.Young, R. C.; Smith, M. E. "Vanadium(III) Chloride" Inorganic Syntheses volume IV, page 128–130, 1953. Upon heating under H2 at 675 °C (but less than 700 °C), VCl3 reduces to greenish VCl2. :: 2 VCl3 \+ H2 → 2 VCl2 \+ 2 HCl Comproportionation of vanadium trichloride and vanadium(V) oxides gives vanadium oxydichloride: :V2O5 \+ VOCl3 \+ 3 VCl3 → 6 VOCl2 Vanadium trichloride catalyses the pinacol coupling reaction of benzaldehyde (PhCHO) to 1,2-diphenyl-1,2-ethanediol by various reducing metals such as zinc:Vanadium-Catalyzed Pinacol Coupling Reaction in Water Xiaoliang Xu and Toshikazu Hirao J. Org. Chem.
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Corrosion inhibitors are chemical compounds that can decrease the corrosion rate of a material, typically a metal or an alloy. NACE International Standard TM0208 defines volatile corrosion inhibitor (VCI) as a chemical substance that acts to reduce corrosion by a combination of volatilization from a VCI material, vapor transport in the atmosphere of an enclosed environment, and condensation onto surface in the space, including absorption, dissolution, and hydrophobic effects on metal surfaces, where the rate of corrosion of metal surfaces is thereby inhibited; also called vapor-phase inhibitors, vapor-phase corrosion inhibitor, and vapor-transported corrosion inhibitor. VCIs come in various formulations that are dependent on the type of system they will be used in; for example, films, oils, coatings, cleaners, etc. There are also variety of formulations that provide protection in ferrous, nonferrous, or multi-metal applications.
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300px The utilization of heavy fossil fuels or biomass rich in carbohydrates, (C6H10O5)n, for fuels or chemicals requires an initial thermochemical process called pyrolysis which fractures large polymers to mixtures of small volatile organic compounds (VOCs). A specific method of pyrolysis of biomass, termed "fast pyrolysis," converts particles of biomass to about 10% carbon-rich solid called char, about 15% gases such as carbon dioxide, and about 70% a mixture of organic compounds commonly referred to as "bio-oil" at 500 °C in 1–2 seconds. Pyrolysis: Biomass + Heat → 0.70VOCs + 0.10Char + 0.15Gases The volatile organics can be collected as a brown, highly acidic liquid for further thermochemical conversion by traditional processes such as steam reforming, gasification, catalytic partial oxidation, catalytic cracking, combustion, or hydrotreating. Catalytic steam reforming: VOCs + H2O + Heat + Catalyst → H2 \+ CO + Catalyst Catalytic partial oxidation: VOCs + O2 \+ Catalyst → H2 \+ CO + Heat + Catalyst Catalytic combustion: VOCs + O2 \+ Catalyst → CO2 \+ H2O + Heat + Catalyst These two sets of chemistries, pyrolysis and catalytic processing, are combined to form the reactive flash volatilization process.
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