Trace pollutants

K. K. Vemia, A. J. H. Louter, A. Jain, E. Pocumll, J. J. Vreuls and U. A. Th Brinkman, On-line solid-phase exti action-gas chromatography-ion cap tandem mass spectro-metiic detection for the nanogram per litre analysis of trace pollutants in aqueous samples , Chromatogmphia44 372-380 (1997). 

Models of chemical reactions of trace pollutants in groundwater must be based on experimental analysis of the kinetics of possible pollutant interactions with earth materials, much the same as smog chamber studies considered atmospheric photochemistry. Fundamental research could determine the surface chemistry of soil components and processes such as adsorption and desorption, pore diffusion, and biodegradation of contaminants. Hydrodynamic pollutant transport models should be upgraded to take into account chemical reactions at surfaces. 

DNA analysis, performance of polymerase chain reactions, clinical assays for pH, enzymes, proteins, oxygen etc., trace pollution monitoring and other sorts of biological analyzes are at the focus of recent developments [5]. Another reference lists environmental monitoring (including speciation), clinical monitoring, and quality control in production processes as applications of pTAS equipment in chemical analysis [30]. 

An essential step in the analysis of trace pollutants in environmental matrices is the pretreatment procedure. Methods that are more efficient have been developed in the last few years, facilitating subsequent chromatographic analysis. Because of the complexity of the matrices, the sample pretreatment procedure includes both extraction and purification of the target analytes. 

For sufficiently low coverages (such as those expected for low bulk concentrations, e.g. trace pollutants), the adsorption isotherms, equation (2), revert to linear ones ... 

Further studies are needed to give better dose-response information and to provide a frequency distribution of the population response to oxidants alone and in combination with other pollutants at various concentrations. Such studies should include the effects of mixed pollutants over ranges corresponding to the ambient atmosphere. The mixtures should be carefully characterized to be sure of the effects of trace pollutants on sulfate aerosol formation. The design of such studies should... 

One of the central problems in air pollution research and control is to determine the quantitative relationship between ambient air quality and emission of pollutants from sources. Effective strategies to control pollutants can not be devised without this information. This question has been mainly addressed in the past with source-oriented techniques such as emission inventories and predictive diffusion models with which one traces pollutants from source to receptor. More recently, much effort has been directed toward developing receptor-oriented models that start with the receptor and reconstruct the source contributions. As is the case with much of air pollutant research, improvements in pollutant chemical analysis techniques have greatly enhanced the results of receptor modeling. 

FIGURE 2.22 Maximum concentrations of some trace pollutants and the percentage of the peak ozone they form when summed. Also shown is the California Air Quality Standard for O, and the various alert levels (from Tuazon et at., 1981). 

Tuazon, E. C., A. M. Winer, and J. N. Pitts, Jr., Trace Pollutant Concentrations in a Multiday Smog Episode in the California South Coast Air Basin by Long Path Length Fourier Transform Infrared Spectroscopy, Environ. Sci. Technol., 15, 1232-1237 (1981). 

Clearly, such adsorption-desorption processes on the surfaces of chambers potentially can have substantial effects on the observed levels of 03 and other trace pollutants and on their rates of formation. While such effects can be minimized using bake-out while pumping if the chamber is evacuable, relatively few smog chambers have such capabilities at present. Even for evacuable chambers, contamination from adsorption on, and desorption from, the walls occurs. How to correct the results for this and reliably extrapolate the data to real atmospheres remains problematical. 

Hankemeier TH, Louter AJH, Rinkema FD, et al. 1995. On-line coupling of solid-phase extraction and gas chromatography with atomic emission detection for analysis of trace pollutants in aqueous samples. Chromatographia 40(3-4) 119-124. 

In many instances, radiotracers are the cheapest method of tracing pollutant flow. 

Viet, P.H., Hoai, P.M., Ha, N.P., Lieu, T.T., Dung, H.M., Tuyen, L.H., 2002. Distribution and behavior of endocrine disrupting chemicals in River and estuary environment from Vietnam. In Proceedings of the UNU International Symposium on Tracing Pollutants from Agrochemical Use Focus on EDC Pollution. Hanoi, Vietnam, April 15-16, 2002. 

Muller, S.R., Wehrli, B., Wiiest, A., Xue, H. and Sigg, L. (1997) The fate of trace pollutants in natural waters - lakes as real-world test tubes . Chimia, 51, 935-940. 

Tuazon EC, Winer AM, Graham RA, et al. 1981a. Atmospheric measurement of trace pollutants Long path fourier transform infrared spectroscopy. EPA- 600/S3-81-026. US EPA Research Triangle Park, NC. 

Many chemists depend on instruments known as mass spectrometers. Mass spectrometers can detect trace pollutants in the atmosphere, provide information about the composition of large molecules, and help to determine the age of Earth s oldest rocks. 

Electrochemistry is important in other less obvious ways. For example, the corrosion of iron, which has tremendous economic implications, is an electrochemical process. In addition, many important industrial materials such as aluminum, chlorine, and sodium hydroxide are prepared by electrolytic processes. In analytical chemistry, electrochemical techniques use electrodes that are specific for a given molecule or ion, including H+ (pH meters), F, Cl , and many others. These increasingly important methods are used to analyze for trace pollutants in natural waters or for the tiny quantities of chemicals in human blood that may signal the development of a specific disease. 

Lead is present at high concentration in emissions from oil combustion, iron and steel production, primary non-ferrous metal production and waste incineration (13). Often complications of identifying sources by their isotopic composition arise when the emission are mixtures of Pb from different primary origins with different isotopic compositions. The importance of Pb as an isotopic tracer was demonstrated by Chow and Johnstone (14) more than three decades ago when they showed that petrol was the major source of pollution in the Los Angeles Basin. It has also been used since, but not extensively. Mating et al. (15) used it to trace polluted air masses through western Europe, while Sturges and Barrie (16) followed pollution across the Canada-USA border. Hopper et al. (17) successfully... 

Hydrogen peroxide (H202) and 03 are the natural strong oxidants present in rainwater. These oxidants can potentially oxidize nearly all the S02 in a parcel of air. Box 3.8 shows that under such conditions rainfall may well have pH values lower than 3. This illustrates the high acid concentrations possible in the atmosphere as trace pollutants are transferred from the gas phase to droplets. Liquid water in the atmosphere has a volume about a million times smaller than the gas phase thus a substantial increase in concentration results from dissolution. 

Thomas W. 1986. Accumulation of airborne trace pollutants by arctic plants and soil. Water Sci Technol 18 47-57. 

Polynuclear aromatic hydrocarbons (PAH) are formed by pyrosynthesis during the combustion of organic matter and have widespread occurrence in the environment. PAHs are found as trace pollutants in soil, air particulate matter, water, tobacco tar, coal tar, used engine oil, and foodstuffs such as barbequed meat. Many PAHs are carcinogenic in experimental animals (e.g., benzo(a)pyrene) and are implicated as causative agents in human cancers. Analytical techniques include HPLC and GC. Advantages of HPLC are the ability to resolve isomeric PAHs, and the selective and sensitive quantitation by UV and fluorescence detection. U.S. EPA methods for PAH are 550.1,610, and 8310. 

In order to control combustion efficiency, intensity, flame signatures, emissions of trace pollutants, and combustion instability, the flame structure must be controlled. Combustion characteristics can be controlled using either active or passive techniques. Even though the active control techniques may be more effective than passive, the active techniques are more expensive, complicated, and... 

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