Tracers volatile

The radioactive isotopes available for use as precursors for radioactive tracer manufacturing include barium [ C]-carbonate [1882-53-7], tritium gas, p2p] phosphoric acid or pP]-phosphoric acid [15364-02-0], p S]-sulfuric acid [13770-01 -9], and sodium [ I]-iodide [24359-64-6]. It is from these chemical forms that the corresponding radioactive tracer chemicals are synthesized. [ C]-Carbon dioxide, [ C]-benzene, and [ C]-methyl iodide require vacuum-line handling in weU-ventilated fume hoods. Tritium gas, pH]-methyl iodide, sodium borotritide, and [ I]-iodine, which are the most difficult forms of these isotopes to contain, must be handled in specialized closed systems. Sodium p S]-sulfate and sodium [ I]-iodide must be handled similarly in closed systems to avoid the Uberation of volatile p S]-sulfur oxides and [ I]-iodine. Adequate shielding must be provided when handling P P]-phosphoric acid to minimize exposure to external radiation. 

The existence of bismuthine was first demonstrated by using a radioactive tracer, Bi (8). Acid treatment of a magnesium plate coated with Bi resulted in the hberation of a volatile radioactive compound. In subsequent experiments, magnesium bismuthide [12048-46-3], Mg Bi, was treated with acid the yield, however, was only one part of bismuthine for every 20,000 parts of bismuth dissolved. Attempts to prepare bismuthine by reduction of bismuth trichloride with a borohydride have not been particularly successful. Experimental quantities ate best prepared by disproportionation of either methylbismuthine [66172-95-0], CH Bi, or dimethylbismuthine [14381-45-4], C2H. Bi (7) ... 

Applications that have been tested with good results are cases where nitrous oxide has been the air contaminant of current interest or used as a tracer gas. Other applications have been carbon disulfide in a rayon factory and styrene vapor, one of the volatile components from a surface-coating material. 

Note that the chemical dimensions do not yield such robust "markers", or tracers, as the isotopic dimensions. For a given combustion source, for example, one is apt to find chemical--but not isotopic—fractionation varying significantly with time, particle size, particle history (differential volatilization or reaction), etc. The ratio K/Fe, for example, was quite different in the fine and coarse fractions from a slash burn (1.5 vs. 0.3) [33] and Pb/Br, which has been popular as an automobile exhaust tracer, varies with the "age" of urban particles [22]. 

Comba ME, Palabrica VS, Kaiser KLE. 1994. Volatile halocarbons as tracers of pulp mill effluent plumes. Environmental Toxicology and Chemistry 13(7) 1065-1074. 

Step 1. Leak testing is performed by adding a small amount of a special volatile chemical tracer to the contents of a tank or pipeline these chemicals are selected for their compatibility with tank and pipeline systems, as well as the lack of their presence in the environment around the tank the tracer is added at a concentration of only a few PPM, and thus has no impact on the physical properties of tank and pipeline contents. 

The evaporation of water and transfer of SFe (a volatile gas tracer) across an air-water interface is measured for three systems ... 

Rivers are generally considered as a plug flow reactor with dispersion. Determination of the dispersion coefficient for rivers was covered in Chapter 6, and determination of the gas transfer coefficient is a slight addition to that process. We will be measuring the concentration of two tracers a volatile tracer that is generally a gas (termed a gas tracer, C) and a conservative tracer of concentration (Cc). The transported quantity... 

Batch Technique. As with river reaeration measurements, tracers can also be put into lakes, estuaries, and oceans to measure the influence of wind on liquid film coefficient. If we have a volatile tracer in a lake with a well-established mixed layer, for example, we can apply the same batch reactor equation from Section 6.A, as though we had a well-mixed tank ... 

Dual Tracer Technique. The dual tracer measurement technique utilizes two gas tracers with diffusion coefficients that are substantially different, such as He and SFe. This technique can also be utilized with one volatile (gas) tracer and one nonvolatile tracer. We will derive the relevant equations to determine hquid film coefficient from the diffusion equation for both cases, beginning with the two gas tracers. 

Equation (9.17) applies to two volatile tracers and equation (9.18) to one volatile and one nonvolatile tracer. 

Zweidinger, R. B., R. K. Stevens, C. W. Lewis, and H. Westburg, Identification of Volatile Hydrocarbons as Mobile Source Tracers for Fine-Particulate Organics, Environ. Sci. Technol., 24, 538-542 (1990). 

P 24.3 Using a Volatile Organic Compound as Tracer for Quantifying Oxygen Demand in a Polluted River... 

CARRIER. (I) A neutral material such as dialomaceous earth used to support a catalyst in a large-scale reaction system. (2) A gas used in chromatography to convey the volatilized mixture to be analyzed over the bed of packing that separates the components. (3) An atomic tracer carrier a stable isotope or a natural element lo which radioactive atoms of the same element has been added for purposes of chemical or biological research. 

Wiedemeier and coworkers (1996) have suggested two methods to approximate biodegradation rates in groundwater field studies (a) use a biologically recalcitrant tracer (e.g., three isomers of trimethylbenzene) in the groundwater to correct for dilution, sorption, and/or volatilization and calculate the rate constant by using the downgradient travel time or (b) assume that the plume has evolved to a dynamic steady-state equilibrium and develop a one-dimensional analytical solution to the advection-dispersion equation. 

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