The ability to detect a broad range of chemical species in the atmosphere, geosphere, and hydrosphere, over a wide range of ambient levels and conditions, is a key enabling technology both for environmental monitoring and for sensing the presence of hazardous materials such as explosives or chemical agents. In this paper we describe several recent developments in the area of high-sensitivity chemical monitoring, including Cavity RingDown Spectroscopy (CRDS) and Raman spectroscopy. Significant improvements in the sensitivity of both ultraviolet and infrared CRDS have been made in our laboratory during the past year. Infrared CRDS, employing tunable infrared optical parametric oscillators, multilayer dielectric high-reflectivity mirrors, and membrane preconcentrator technology, may have the potential for detecting vapors from concealed explosives as well as a wide variety of volatile organic compounds present at parts-per-billion levels or below. Sensitivity enhancement techniques for Raman spectroscopy, such as Surface-Enhanced Raman Spectroscopy, may achieve similar sensitivities for samples in ultra-dilute solutions. We also address the relationship of novel monitoring techniques, such as these high-sensitivity detection methods, to current and future regulatory issues.

Dioxins, which are already known to exist in the environment, are strongly carcinogenic, and, therefore, it is requested to develop a new analytical instrument for their trace analysis. There are many isomers in dioxins and their toxicities are very different, and, as a result, a selective analytical means is essential for analysis. At the same time, the concentrations of dioxins are generally very low, and it is needed to develop a sensitive analytical means as well. Gas chromatography combined with mass spectrometry is currently used for analysis of dioxins. It is, however, difficult to apply this method to on-line real-time monitoring of dioxins emitting from an incinerator. On the other hand, supersonic jet spectrometry combined with multiphoton ionization/mass spectrometry (SSJ/MPI/MS) is suitable for this purpose, because of its high selectivity given by optically-selective ionization, allowing on-line real-time monitoring of dioxins and their precursors. In this study, we developed SSJ/MPI/MS and used in the detection of chemical species formed in the chemical reaction of dioxin precursors in the presence and absence of a catalyst. It was found that chlorination and dimerization reactions occur efficiently in the presence of FeCl₃. Thus, this approach based on SSJ/MPI/MS provides a useful analytical means for continuous monitoring of dioxins and their precursors. We also developed several analytical techniques for the improvement of sensitivity, which include designs of a new type of picosecond dye laser and of ion focusing optics, and a digital counting technique.

Monitoring and control of industrial or biotechnological processes invariably require reliable and fast analytical systems. Two-dimensional spectral fluorescence allows real time automatic measurements directly inside the process and provides a continuous stream of information compared to discrete information available from repeated sampling and offline analysis. Normally, chromatographic molasses desugarization processes are typically monitored with a combination of an online-refractometer, polarimeter and the measurement of density and conductivity. Additional information of the separation profile could be obtained by multiple sampling during the separation cycle followed by offline laboratory analysis. An optical sensor (BioView^R) allows online fluorescence measurements for a continuous monitoring directly at the outlet of the separation columns. It was the aim to predict the amino acid serine during the chromatographic cycle. Based on fluorescence, it was possible to monitor a fluorophor, which eluted a few minutes before the serine fraction during molasses desugarization. The application of fluorescence measurements for monitoring and control of chromatographic separation process may improve yield and purity of the separating fractions and can lower the costs for the next downstream processing of by-products.

Electromagnetic Radiography (EMR)^TM provides direct, high- resolution images of low-level chemical contamination in the ground at concentration levels in the parts-per-billion range ((mu) g/kg). This new sensor system can distinguish between dense, non-aqueous phase liquids (DNAPLs) and light, non- aqueous phase liquids (LNAPLs). Ionic chemicals can be distinguished from non-ionic chemicals, and dissolved-phase chemicals in the water table can be distinguished from liquid- phase contaminants in the vadose zone trapped in the pore spaces of the soil. EMR^TM is derived from high-performance ground-penetrating radar (GPR). Like its predecessor, EMR^TM provides direct images of subsurface geologic structures, including faults, fracture zones, bedrock profiles, bedding planes, clay lenses and infiltration zones. The system employs electromagnetic impulses in the radio- frequency range of 30 MHz to 480 MHz. Specific chemicals have been found to produce unique responses in this frequency domain, leading to the discovery that discrete energy bands are being excited at the molecular level. Much work remains to be done on the characterization of specific chemicals in the radio-frequency (RF) domain. Meanwhile, conventional soil testing can be used to identify the chemicals and 'calibrate' the EMR^TM field data. It is now possible to use non- intrusive remote sensing techniques to map the lateral and vertical distribution of specific low-level chemical contaminants on a production basis. The EMR^TM system is currently capable of providing 100 percent volumetric inspection of 3 to 5 acres per day to a depth of several meters, including clay.

Pattern recognition (PR) and signal/image processing methods are among the most powerful tools currently available for noninvasively examining spectroscopic and other chemical data for environmental monitoring. Using spectral data, these systems have found a variety of applications employing analytical techniques for chemometrics such as gas chromatography, fluorescence spectroscopy, etc. An advantage of PR approaches is that they make no a prior assumption regarding the structure of the patterns. However, a majority of these systems rely on human judgment for parameter selection and classification. A PR problem is considered as a composite of four subproblems: pattern acquisition, feature extraction, feature selection, and pattern classification. One of the basic issues in PR approaches is to determine and measure the features useful for successful classification. Selection of features that contain the most discriminatory information is important because the cost of pattern classification is directly related to the number of features used in the decision rules. The state of the spectral techniques as applied to environmental monitoring is reviewed. A spectral pattern classification system combining the above components and automatic decision-theoretic approaches for classification is developed. It is shown how such a system can be used for analysis of large data sets, warehousing, and interpretation. In a preliminary test, the classifier was used to classify synchronous UV-vis fluorescence spectra of relatively similar petroleum oils with reasonable success.

In this paper we describe the detection of polychlorinated biphenyls (PCBs) which is based on the measurement of changes of optical absorption at 400 nm of the medium in an aerobic bioreactor with immobilized cells Pseudomonas species 2. The rate of production, composition and the concentration of yellow intermediates are influenced by concentration and composition of PCB mixtures, concentration of cells and by the methods of immobilization. The method was applied in the detection of commercial mixture D103. It was found that the advantageous carriers were inorganic or organic-inorganic matrices, which sorbed PCBs and a cell outgrowth from their surface was low. In water contaminated with transformer oil and chlorinated hydrocarbons the detection limit is 10^-2 g_D103/kg. In transformer oil the upper limit for degradation of D103 by sodium dehalogenation (1.5 g_D103 /kg_oil) was determined also in the presence of the same concentration of trichloroethylene. The employment to of a liquid core waveguide spectrophotometer instead of a diode array spectrophotometer increased the sensitivity of the measurement of yellow intermediates by a factor of 100. An extrinsic fiber-optic sensor was used for in-situ measurement during biodegradation of PCBs in bioreactors.

Polycyclic aromatic hydrocarbons (PAHs) have attracted spectroscopists, astrophysicts and environmentalist because of their importance in our day to day life. It is well known that epoxides are produced during the metabolism of PAHs and have the requisite chemical reactivity to qualify them for the role as an ultimate carcinogenic form of PAHs. Several carcinogenic PAHs such as 3.4-benzopyrene, 1.2,3.4-dibenzopyrene, 3.4,9.10- dibenzopyrene etc. are found to be present in tobacco smoke and among air pollutants. Although PAH molecules are being studied for last several years by using conventional spectroscopy but no systematic attempt has been made to study non-radiative transitions. In our laboratory, we have studied many PAH molecules by a non-destructive technique with unique capability and sensitivity, known as Photoacoustic (PA) spectroscopy. PA spectroscopy is an analytical and research tool to get information about non-radiative transitions and singlet-triplet electronic transitions, where the conventional spectroscopic technique fails. The study of electronic transitions of some carcinogenic molecules are reported using PA and optical absorption spectra in boric acid glass in the region 250 - 400 nm. The electronic transitions of these molecules observed experimentally, have been interpreted using the optimized geometries and CNDO/S-CI method. A good agreement is found between the experimental and calculated results. Assignments of observed electronic transitions are made on the basis of singlet-triplet electronic transitions. Vibrations attached to these electronic transitions are attributed to the ground state vibrational modes.

The aim of this paper is to outline the potential of remote sensing and GIS techniques as tools for the management of data rich environments, as complex coastal areas, exposed to industrial pollution phenomena. The area of study, Pianura Pontina is located in central Italy, 70 km south of Rome. In particular the possible patterns of surface and ground waters pollution have been considered. Furthermore the interactions between industrial installations, water resources, protected areas and urban settlements have been analyzed. Landsat TM satellite images have been processed in order to obtain a land-use map that has been inserted in a GIS database and integrated with further information like lithology, geological structure and stratigraphy, hydrogeological features, DEM, industrial plants location and characters. This allowed the creation and processing of different thematic maps: vulnerability, risk, impact. The methodology can be a reliable, sensible and easy to update support to competent Authorities in environmental management.

The need for high resolution spatial and temporal measurements of tropospheric ozone is discussed. Tropospheric ozone is globally increasing due to anthropogenic sources such as industrialization and biomass burning. In addition to its hazardous effects during pollution episodes, elevated levels of tropospheric ozone may have additional detrimental environmental effects due to ozone's crucial role in tropospheric chemistry and in global climate. Ground-based lidar instruments can play an important role in meeting this measurement need. We present test results for a prototype compact, minimal-cost ozone lidar. The instrument is designed to be as reliable and simple as possible but still be capable of routinely measuring ozone profiles with less than 10% relative error from the ground up into the lower stratosphere. In addition to local pollution monitoring, this lidar satisfies the basic requirements necessary for future global monitoring projects requiring multi-instrument networks, such as that proposed for the Global Tropospheric Ozone Project (GTOP). GTOP is currently being formulated by a scientific panel of the International Global Atmospheric Chemistry Project to meet its goal to better understand the processes that control the global sources, sinks, and transformation mechanisms of tropospheric ozone.

Global climate change depicts energy exchange balance between the earth and atmosphere and the space. The balance is affected by human activities -- burning of fuel -- fossil or biological generating carbon dioxide, nitrous oxide or trace gases. Accumulation of these gases in the atmosphere may follow intensification of green house effect and cause global sea warming. Warming may affect agriculture, forestry, water resources and rising or falling of levels. The burning of fuel is for the generation of commercial energy -- electricity, household energy -- cooking, heating or burning of bushes, waste product and biomass. The world population distribution reveals heavy tilt in terms of growth rate and the cumulative figure. Nearly 80% of the world population is in the developing economy with only 20% resource available to them. The energy demand in five major Asian developing economy for the year 1990 is summarized.

A commercially available, hand-held chemical vapor detector was modified to detect Gram-positive Bacillus subtilis var. globigii spores (BG) in outdoor field scenarios. An Airborne Vapor Monitor (AVM) ion mobility spectrometry (IMS) vapor detector was interfaced to a biological sample processing and transfer introduction system. The biological sample processing was accomplished by quartz tube pyrolysis (Py), and the resultant vapor was transferred by gas chromatography (GC) to the IMS detector. The Py-GC/IMS system can be described as a hyphenated device where two analytical dimensions, in series, allow the separation and isolation of individual components from the pyrolytic decomposition of biological analytes. Gram positive spores such as BG contain 5 - 15% by weight of dipicolinic acid (DPA), and picolinic acid is a pyrolysis product of DPA. Picolinic acid has a high proton affinity, and it is detected in a sensitive fashion by the atmospheric pressure-based IMS device. Picolinic acid occupies a unique region in the GC/IMS data domain with respect to other bacterial pyrolysis products. A 1000 to 1, air-to-air, aerosol concentrator was interfaced to the Py-GC/IMS instrument, and the system was placed in an open-air, Western United States desert environment. The system was tested with BG spore aerosol releases, and the instrument was remotely operated during a trial. A Met-One aerosol particle counter was placed next to the Py-GC/IMS so as to obtain a real-time record of the ambient and bacterial aerosol challenges. The presence/absence of an aerosol event, determined by an aerosol particle counter and a slit sampler-agar plate system, was compared to the presence/absence of a picolinic acid response in a GC/IMS data window at selected times in a trial with respect to a BG challenge. In the 21 BG trials, the Py-GC/IMS instrument experienced two true negatives, no false positives, and the instrument developed a software failure in one trial. The remaining 18 trials were true positive determinations for the presence of BG aerosol, and a limit of detection for the Py-GC/IMS instrument was estimated at approximately 3300 BG spore-containing particles.

We extend our previous work on two-dimensional angular optical scattering (TAOS) patterns to water droplets with inclusions and absorption studies at two different wavelengths. Using an acoustic levitator, the TAOS from water droplets containing polystyrene latex sphere inclusions is observed as the droplet evaporates leaving only a dry aggregate of spheres. Dramatic changes in the TAOS patterns occur even when the droplet still has a large volume fraction of water. Two wavelengths (266 nm and 532 nm) are used to examine the TAOS patterns from droplets containing tryptophan. The effect absorption has on the angular scattering peaks is presented. Such dual wavelength measurements can provide useful information to those working on the inverse problem.

Luciferin-Luciferase (L-L) luminescence techniques were used to successfully measure adenosine triphosphate (ATP) (pg/ml) in concentrated aerosol samples containing either vegetative bacterial cells or spores. Aerosols were collected with wet and dry sampling devices. Evaluation for the presence of total bio-mass from bacterial and non-bacterial sources of ATP was achieved by suspending the collected aerosol samples in phosphate buffered saline (PBS), pipeting a 50-(mu) l aliquot of the PBS suspension into a Filtravette^TM, and then adding bacterial releasing agent (BRA). The sample was then reacted with L-L, and the resulting Relative Luminescence Units (RLU's), indicative of ATP from all sources, were measured. Bacterial cells were enumerated with the additional application of a wash with somatic cell releasing agent (SRA) to remove any interferences and non-bacterial sources of ATP prior to BRA application. This step removes interfering substances and non-bacterial sources of ATP. For spore analysis, an equi-volume sample of the PBS suspension was added to an equi-volume of trypticase soy broth (TSB), incubated at 37 C for 15 minutes, and processed using methods identical to bacterial cell analysis. Using these technique we were able to detect Bacillus subtilin variation niger, formerly known as Bacillus globigii (BG), in aerosol samples at concentrations greater than or equal to 10⁵ colony forming units (CFU) per ml. Results of field and chamber trials show that one can detect the presence of bacterial and non-bacterial sources of ATP. One can also differentiate spore and vegetative bacterial cells. These techniques may be appropriate to situations where the measurement of bacterial aerosols is needed.

Under contract to the U.S. Air Force and Navy, Pacific Advanced Technology has developed a very sensitive infrared imaging spectrometer that can perform remote imaging and spectro-radiometry. One of the most exciting applications for this technology is in the remote monitoring of smoke stack emissions and fugitive leaks. To date remote continuous emission monitoring (CEM) systems have not been approved by the EPA, however, they are under consideration. If the remote sensing technology is available with the sensitivity to monitor emission at the required levels and man portable it can reduce the cost and improve the reliability of performing such measurements. Pacific Advanced Technology (PAT) believes that it currently has this technology available to industry. This paper will present results from a field test where gas vapors during a refueling process were imaged and identified. In addition images of propane from a leaking stove will be presented. We at PAT have developed a real time image processing board that enhances the signal to noise ratio of low contrast gases and makes them easily viewable using the Image Multispectral Sensing (IMSS) imaging spectrometer. The IMSS imaging spectrometer is the size of a camcorder. Currently the data is stored in a Notebook computer thus allowing the system to be easily carried into power plants to look for fugitive leaks. In the future the IMSS will have an embedded processor and DSP and will be able to transfer data over an Ethernet link.

The high toxicity of mercury species (elemental and compound) has prompted a demand for accurate, real-time inventory and control of their emissions. Our method of choice for mercury compound vapor is Photofragment Fluorescence spectroscopy. Target compound concentrations can be related to the fluorescence intensity from an excited fragment. Fragment identities and distributions, as revealed in the fluorescence spectrum provide information on the composition of the parent species. In the first experimental phase, a static cell (no flow) containing mercury compound (e.g. HgCl₂ vapor was probed with a deep ultraviolet (UV) laser to generate characteristic spectra. An atmospheric pressure flow cell was used in the second stage. Limits-of-detection have been estimated. Detection schemes have included both photomultiplier tube (with interference filter) and charge- coupled-device camera (with monochromator). To reduce fluorescence quenching, we have expanded an argon gas stream containing Hg vapor through a micro-jet into a vacuum. The jet is crossed with a laser beam at 253.7 nm to excite atomic fluorescence, which is distinguished from the background by time gating.

The ideal method for rapid, precise and accurate analyses of the chemical composition of microbial systems, both within biotechnology and for the identification of potentially pathogenic organisms, would have minimum sample preparation, would analyze samples directly, would be rapid, automated, accurate and (at least relatively) inexpensive. With recent developments in analytical instrumentation, these requirements are increasingly being fulfilled by the vibrational spectroscopic methods of Fourier transform-infrared spectroscopy (FT-IR) and dispersive Raman microscopy. Both techniques are extremely rapid, taking seconds rather than minutes to collect a spectrum from a sample and are fully automated. This paper gives an overview of some of the biotechnological and clinical studies that are currently in progress in 'The Aberystwyth Quantitative Biology' and 'Molecular and Spectroscopic Systematics' groups within the Institute of Biological Sciences, University of Wales, Aberystwyth.

The rapid detection of toxic contaminants released into the air by chemical processing facilities is a high priority for many manufacturers. This paper describes a novel biosensor for the remote monitoring of toxic sites. The proposed biosensor is a measurement system that employs immobilized luminescent Vibrio fisheri bacteria to detect airborne contaminants. The presence of toxic chemicals will lead to a detectable decrease in the intensity of light produced by the bacteria. Both cellular and environmental factors control the bioluminescence of these bacteria. Important design factors are the appropriate cell growth media, environmental toxicity, oxygen and cell concentrations. The luminescent bacteria are immobilized on polyvinyl alcohol (PVA) gels and placed inside a specially constructed, miniature flow cell which houses a transducer, power source, and transmitter to convert the light signal information into radio frequencies that are picked up by a receiver at a remote location. The biosensor prototype is designed to function either as a single unit mounted on an exploratory robot or numerous units spatially distributed throughout a contaminated environment for remote sensing applications.

Significant reductions in atmospheric emissions of volatile organic compounds (VOC) and greenhouse gases (such as SF₆) are being actively pursued by industrialized countries around the world. GasVue is a relatively new technology having the potential to locate the large leak sources responsible for the majority of these atmospheric emissions many times faster than is currently feasible. The rapid repair of these large leak sources offers the significant emission reductions sought by both industry and regulatory agencies. An overview of the GasVue development history and a brief description of the technology are presented. However, the primary purpose of this paper is to summarize technology evaluations and field test results conducted since 1997. Field test results involving SF₆ leaks in electrical substations, natural gas leaks from underground distribution systems, and VOC leaks from petroleum processing units are described and discussed. Plans for future field tests and improvements to the technology are outlined.

An air-inductively coupled plasma (air-ICP) system has been developed for continuous sampling and monitoring of metals as a continuous emission monitor (CEM). The plasma is contained in a metal enclosure to allow reduced-pressure operation. The enclosure and plasma are operated at a pressure slightly less than atmospheric using a Roots blower, so that sample gas is continuously drawn into the plasma. A Teflon sampling chamber, equipped with a sampling pump, is connected to the stack that is to be monitored to isokinetically sample gas from the exhaust line and introduce the sample into the air-ICP. Optical emission from metals in the sampled gas stream is detected and monitored using an acousto-optic tunable filter (AOTF)-echelle spectrometer system. A description of the continuous sampling air-ICP system is given, along with some preliminary laboratory data for continuous monitoring of metals.

Analysis of concentration different gases in a mixture is very important for many industrial processes on factories, thermal power stations, for control waste gases of factories and automobiles. The remote monitoring of temperature allows to control burning processes on power stations. Information about temperature of flame and concentration some gases (02, H₂, NO, and CO) in an exhaust gas mixture may be used for automation technological processes on power stations.

At monitoring from flying apparatus of impurity gases in atmosphere an opportunity of lidars use are limited by virtue of low of an energy level of a scattered laser signal. The certain advantages, in this sense, are kept for spectrometers working in solar light. For example, in a window 1400 - 1700 nm, spectral density of radiation from a surface of ground is 200 W/m²/mkm. At such measurements the level of radiation falling on the photoreceiver does not depend on height of flight, and is determined by product of squares of the linear and angular apertures on a spectrometer input. At the same time it is known, that, at the given requirement under the resolution, the spectrometer work effectiveness is reduced in accordance with increase of the angular aperture. In the article Fabry-Perot interferometer behavior, with conjugate convex-concave mirrors, is considered. For this purpose by the method of Green's functions, in spherical coordinates, it is solved the non-uniform wave equation for a source uniform -- distributed in the coordinates origin. Is received, that the field on a surface of interferometer mirrors is increased only at increase of the cross sizes of a source up to 2 - 3 lengths of radiation waves. From a kind of the decision follows, that introduction in source area of an amplitude or phase mask of determined frequency consisting of rings results in increase of a signal on the interferometer mirror in a wide increasing range of the source sizes. From results of the decision of this problem follows, that for a return course of beams with the large angular aperture, from interferometer to center of curvature there is the system of concentric rings with shifts on a phase on 180 degrees. Introduction of a phase or amplitude mask allows to compensate or to remove appropriate antiphase components and by that essentially to increase a signal power level, and, accordingly, sensitivity of the device.

The present paper describes an Electro-Optical Monitoring System developed for the real time in-situ monitoring of Ammonia (NH₃) emissions, at very low concentrations in air, well below the hazardous levels. Ammonia is the starting chemical for almost all industrially produced nitrogen compounds and is therefore one of the most important inorganic raw materials. Due to its unique chemical and physical characteristics, the Ammonia (NH₃) anhydrous gas is used in various industrial applications such as: Air Conditioning, Refrigeration (including space shuttles), Agriculture and Chemical Processing. NH₃ gas, being a highly irritant toxic and flammable gas with a pungent odor detectable by human perception at 53 ppm, has a TLV-TWA of 25 ppm (TLV-STEL of 35 ppm) and a lower explosive limit (LEL) of 15% in air. Being extremely corrosive and irritating to the skin, eyes, nose and respiratory tract, (irritation begins at 130 - 200 ppm), exposures to high concentrations (above 2500 ppm) are life threatening, thus early detection of Ammonia at concentrations up to 50 ppm is essential to prevent its toxic influence. Existing detection methods for NH₃ rely mainly on chemical sensors and analytical methods that require the gas to be sampled and introduced into the detection system via a probe, compared to various standards (for determining the concentration) and the result is not always reflecting the actual gas concentration. The emerging optical open path remote sensing technology that analyzes the specific 'finger print' absorption characteristics of NH₃ in various narrow spectral bands, specifically in the UV solar blind band, is discussed including the rationale of the detection algorithm and system design. The system offers warning and alarm signals set at the above low concentration detection sensitivity, (10 - 50 ppm(DOT)m) thus providing reliable Ammonia detection over an air path from 3 (including air-duct applications) to 400 ft (1 - 120 m). Typical installations of Ammonia Monitoring Systems, field and laboratory test data are discussed, including spectral cross sensitivity analysis with interfering chemicals and changing environmental conditions (heat, humidity).

In this work it is presented the design and the preliminary results of a new prototype of luminometer, that allows to distinguish the signals from the same analyte (dissolved O₂) in different places (multiposition analysis) by using room temperature phosphorescence (RTP) measurements. The system uses an Intensified Charge-Coupled Device (ICCD) as detector. CCD detectors can provide multichannel detection and this offers a very important potential to measure simultaneously and distinguish the signals from different optical fibers placed at different height at the monochromator entrance slit. Bifurcated optical fibers are used to carry the light from the excitation source (a Xe flash lamp) to the sensing region and to conduct the RTP emission to the monochromator entrance slit. The developed system is used with four bifurcated optical fibers in order to measure simultaneously the RTP emission from four sensing materials placed at the end of bifurcated optical fibers.

The presented mobile sensor system consists of a LIF spectrometer, a reflectance spectrometer and a temperature sensor. It is possible to connect more sensors for example a fiberoptic pH sensor or a fiberoptic oxygen sensor. The LIF spectrometer is suitable for measuring mineral oils, PAHs or herbicides directly from soils, waters and process streams with a fiber-optic multichannel setup. The LIF sensor consists of a low-cost nitrogen laser which can pump a dye laser. A spectral analyzer equipped with a CCD camera is used as detector. Reflectance spectroscopy measurements are made using a tungsten halogen light source. The same probe is used for both techniques, LIF and reflection spectroscopy. It is coupled into the system by an optical fiber. The device is controlled by a computer which is also used to analyze the measured data. The sensor system is installed in a small trolley. This set up is suitable for a rapid analysis of many samples, which is an advantage in comparison with standard chemical analytics. It can be used to screen larger contaminated areas for mineral oils and PAHs. Also in case of an emergency situation, for example after an accident, the device is useful to cut down the time of sampling and the time one has to wait for the results.

We describe solid state gas microsensor array technology for real-time, low-cost environmental and industrial monitoring. The four-element, surface-micromachined arrays are designed in CMOS technology and consist of multiple platforms called 'microhotplates.' Each microhotplate can be individually addressed, and includes functionality for rapid control and measurement of sensor temperature and gas-induced changes in a sensing film's electrical properties. The array elements can be tuned for specific analytes, by choice of sensing material and the temperature-programs applied, in order to better meet the needs of a particular application. Tin oxide was used as the base sensing material for microhotplates used in these studies. Tin oxide is grown selectively on each individual element within the arrays using a chemical vapor deposition process involving thermal decomposition of tetramethyltin in an argon and oxygen ambient. Catalytic additives, such as Pt, Pd and Cu are surface-dispersed to make the films more selective and sensitive. Detection capabilities for the low power microhotplate sensing technology are being established for target analytes in ambients that are relevant to process control, environmental measurements, and vapor-related remediation studies. We describe the use of these micromachined arrays to detect approximately ppm levels of methanol, benzene and hydrogen in ambient air and to produce analyte-specific signatures using temperature programs, T(t).

Conventional immersion aircraft thermometers suffer significant performance limitations, particularly for high- speed aircraft and at high angles-of-attack and side-slip. Moreover, immersion thermometers cannot perform through hot thick aircraft boundary layers and greatly increase the radar cross section of low observable aircraft. OPHIR Corporation has developed passive, remote-sensing thermometers which overcome these significant limitations. In addition, we have developed range-resolved radiometers to provide temperature profiles. Range resolved temperature profiles may enable Clear Air Turbulence, air density fluctuations and other flight hazards to be detected well ahead of the aircraft. A review of OPHIR's radiometer technology is presented. The fundamentals of radiant gas thermometry are introduced. Single wavelength 4.255 micrometer and 15 micrometer radiometers and range- resolved 15 micrometer radiometers are discussed as are data collected from numerous fight test programs. Finally, a laboratory demonstration of the multi-range capabilities of radiometers is discussed.

The toxicity of heavy metals is well documented today and legislation for their control in seawater continuously becomes more and more restrictive. In order to control and ensure the marine environment quality it is demanded an effort to develop new analytical tools, which allow the analysis of trace levels of heavy metals in seawater. The measurement of luminescence (phosphorescence and fluorescence) gives rise to high sensitive, selective and innovative approaches which could be used to develop new trace metal sensing methods. In this way, we have observed that the metal-chelates formed between different sulphonic-hydroxyquinolines with heavy metals, such as lead, or the metal-chelates between mercury and purines exhibit strong room temperature phosphorescence and fluorescence, respectively. Based on the formation of such quelates, two luminescence methods are investigated for sensing of lead and mercury in seawater. Optimum experimental conditions and the analytical performance characteristics of the methods are discussed. Relative standard deviations in the order of 4% are typical at 100 ng mL^-1 of Pb(II) and Hg (II). The detection limits are 0.1 and 1.4 ng mL^-1 for lead and mercury, respectively. Possible interferences present in seawater, including sea water cations and anions are evaluated in detail. Finally, the methods are applied to the determination de mercury and lead in seawater samples.

One of the strengths of laser-induced breakdown spectroscopy (LIBS) is the ability to acquire atomic emission spectra for a wide variety of samples non-invasively, with only optical access being required. The use of optical fibers makes the technique ideal for applications where the measurement area of interest is either not accessible or where it is not safe to take a sample. Fiber-optic LIBS probes have been described where a single laser pulse is delivered to the sampling region by one optical fiber and the emission is collected by another. One of the problems with this approach is fiber degradation from the high power laser pulses. To minimize this problem, we are investigating dual-pulse LIBS where the laser power is split between 2 different laser pulses that are separated by a short delay time. We have found in related studies that the use of dual laser pulses to obtain LIBS signals can lead to enhanced intensity and reproducibility for some types of samples. A natural extension of this result is to make dual- pulse measurements using optical fibers. Thus far, we have seen 1.5 to 2 fold enhancements for copper and lead using fiber-optics in various geometries to both deliver the dual laser pulses and collect the emission.

The goal of our research is to develop a sensitive, rugged, real time sensor for land mine detection. Our method relies upon detecting the change in color arising in an amine- containing poly(vinylchloride) (PVC) film when exposed to polynitroaromatics (the main components of charge in a land mine) in the vapor phase. This change is a result of formation of visible light absorbing complexes between primary or secondary amines and polynitroaromatics. The complex with 2,4,6-trinitrotoluene (TNT) absorbs in the visible domain at 500 nm and the complex with 2,4-dinitrotoluene (DNT), a common contaminant and a degradation product of military TNT, absorbs at 430 nm. Complex accumulates over time so that high sensitivity can be achieved by waiting. The rate of color formation for DNT is ca. 10^-5 absorbance units per minute in a saturated DNT vapor atmosphere, at 24 degrees Celsius, when the absorbance is measured through the membrane. Employing the membranes as waveguides would substantially improve sensitivity by increasing the pathlength.

Laser induced acoustic imaging as a prospective technique in landmine detection has been studied experimentally in our previous work. When a laser pulse impinges on the surface of a medium (solid or liquid), several processes occur in a short time, including reflection, absorption, heat conduction, medium expansion and contraction. Acoustic pulses will be generated during this period. Underground objects can be imaged by detecting the echoes of these sound pulses. In this paper, we developed a one-dimensional model for heat generation and sound pulse excitation. The acoustic pulse shape strongly depends on the medium properties and boundary conditions. Results for both a constrained surface and a free surface are given in this paper.

Microwave heating of soil offers the potential to enhance infrared signatures of buried objects such as landmines. In uniform soil, with no vegetation and a flat surface, images can be obtained showing the shape of the objects, to aid in their identification. Combined with other subsurface imaging modalities, this promises a reduced false alarm rate, leading to more effective demining operations. However, in the presence of rough ground, non-uniform soil, vegetation, and solar heating, the signatures become much more complicated. In this work, we examine some of these issues, based on outdoor experiments and a two-dimensional model.

In this paper, we develop a system to exploit sensor fusion for detecting and locating plastic A/P mines. We design and test the system using data from Monte Carlo electromagnetic induction spectroscopy (EMIS) and ground penetrating radar (GPR) simulations. We include the effects of both random soil surface variability and sensor noise. In the presence of a rough surface and a heterogeneous, multi-element clutter environment, we obtain good results fusing EMIS and GPR data using a statistical approach. More generally, we demonstrate a framework for simulating and testing sensor configurations and sensor fusion approaches for landmine and unexploded ordinance (UXO) detection systems. Taking advantage of high- fidelity electromagnetic simulation, we develop a controlled environment for testing sensor fusion concepts, from varied sensor arrangements to detection algorithms. In this environment, we can examine the effect of changing mine structure, soil parameters, and sensor geometry on the sensor fusion problem. We can then generalize these results to produce mine detectors robust to real-world variations.

Modeling of liquid-liquid-extraction processes involves the concentration of the extracted component directly at the interface. Currently, only very few and specialized methods are available for the direct measurement of these concentrations. Therefore a new, fluorescence based measurement system with a high spatial resolution and a broad application spectrum was developed and tested. The detection principle is based on the use of fluorescent dyes, excited by an argon ion laser. The intensity of the emitted light is dependent on the concentration of the extracted component in the very near surroundings of the dye. This intensity distribution is reproduced by an optical, microscope based system onto a highly sensitive camera with a spatial resolution of 1 micrometer. This distribution is converted into a concentration profile at the interface using a calibration function and digital image processing routines. Measurements were performed in a commonly used stirred two phase reactor modified to meet the requirements of an optical measurement system. It could be shown that the concentration profiles at mobile and immobile interfaces can be visualized with a resolution of 1 micrometer. The profiles formed at the interface differ significantly according to the kinetic of the used extraction system and the flow profiles in the reactor and can be used for further modeling of the extraction processes.

Despite considerable research effort put into characterizing environmental aspects of disposal and construction with high- volume 'non-hazardous' waste materials, there is still lack of satisfactory knowledge of their life cycle leaching behavior in the actual field conditions. This often results in false- negative errors in the long-term environment impact assessment (EIA) and severe damage to the renewable ground water resources in the area of the disposal sites either in the operational or post-closure period. This statement has been exemplified in two case studies: (1) Powerplant ash pond under operation sited in the Erai River basin (Maharastra, India), with open water circuit; (2) Reclaimed fly ash (FA) pond in a post-closure period at the dewatering stage sited in a sand quarry (Silesia, Poland). In the first case, EIA on the basis of the monitoring of entirely excess water discharged into the river, caused serious failure in preventing deterioration of usable ground water resources in several communities within and down-gradient of the FA pond. The second case study based on screening pore solution along the vertical profiles of the FA pond displayed deep transformation of FA properties in the post-closure period. At this stage, FA acidification and massive heavy metal release from its matrix due to the change of the saturation zone conditions into the vadose zone occurred. These examples clearly show a need of properly designed and operated life cycle screening/monitoring of the large-volume waste sites to provide an early alert to prevent degradation of recoverable ground water resources. Some concepts of cost-effective monitoring/screening for an early alert have been proposed.

The purpose of this work is the development of a method for the in-situ detection of chemicals in sea water. Raman scattering was chosen as it is a non-intrusive method yielding finger-printing spectra of the analytes. Surface-enhanced Raman scattering (SERS) is used to provide the sensitivity necessary for trace analysis in the environment. SERS active coatings are produced by encapsulating a silver colloid in sol-gel derived xerogel films. The sol is coated onto silicon plates, microscope slides, quartz windows or optical fibers allowing a variety of measurement configurations. Results are presented for a range of aromatic hydrocarbons in sea water measured with methyl triethoxy silane (MTEOS) and ethyl triethoxy silane (ETEOS) based substrates. The suitability for operation in the marine environment is discussed in terms of selectivity, response time, limits of detection, and long term stability. Two compact marinised optodes are presented with a lensed head and a fiber head allowing for in-situ measurements in sea water with exchangeable SERS substrates or coated fibers. The optode is linked via optical fibers to an underwater core instrument containing light source and spectrograph. This is discussed in the context of a multi- disciplinary field-operable measuring device intended for operation depths up to 300 m.

We propose the method of water quality monitoring on the base of resonance Raman and fluorescence spectroscopy. For exciting of second emission from the water samples we have used pulsed copper vapor laser, working at high frequency (10⁴Hz) repetition of short (20 ns) pulses of generation in visible (510,6 and 578,2 nm) region with the average power 1 - 10 W and peak power -- 10⁴ - 10⁵ W. With the help of nonlinear crystal the visible laser emission was transformed to ultraviolet region. In Raman spectra of water solutions we have observed a number of peaks, related to internal and external vibrations of water molecule and some additional peaks, connected with soluted aromatic substances. Our technique permitted to receive the spectra of secondary emission from water samples with different concentration (beginning from 1 ng/L) soluted aromatic compounds and the mixtures of H₂O-D₂O. We also present the results of analysis of the properties of a number of water filter, cleaning the water from imperfections.

The development of an optical-based dosimeter for neutrons and heavy charged particles is described. It is based on the use of three dimensional (3-D) optical memory materials, used in optical computing applications, and multiphoton fluorescence of photochromic dyes. Development and characterization of various types of dosimeter materials are described as well as the optical readout system. In addition, various excitation geometries for 'reading' and 'writing' to the optical memories are also discussed.

Laser-induced breakdown spectroscopy (LIBS) is a very attractive form of elemental analysis which holds much promise as a remote technique. LIBS, however, has problems with sensitivity and reproducibility compared to alternate forms of analysis. One way in which our laboratory is addressing these problems is through the use of dual-laser pulses which have been shown to produce enhanced LIBS signals. Our studies include a systematic approach to the factors affecting the dual-pulse LIBS signals and the mechanisms behind the enhancements observed. For optimizing emission signals, we have found that the laser beam geometry plays a large role. This paper focuses on results solely from a perpendicular beam orientation where a pre-spark is formed above the sample surface by a laser pulse before any material ablation occurs from a second laser pulse. Using this pre-ablation spark, enhancements in copper and lead signal to background ratios are found to be as high as 2 to 6 fold for copper and lead, respectively. The reason for this increase in sensitivity is still unclear but is related to an increase in the extent of sample ablation that occurs. Factors contributing to the LIBS signal are also being investigated by acquiring time-resolved plasma images of the dual-pulsed plasmas. These experiments show changes in the overall size and shape of the plume when using a pre-ablation spark. In addition, the enhancements in lead signal to background ratios appear to be highly region specific.

In the paper the actuality and potential for the IR-Remote Sensor and Lidar in Chines Aerospace are introduced. The IR- Remote Sensor is developed toward the multi-channel, narrow- band and high sensitive. The lidar is developed toward for the aerospace applied the entire solid state, the multi-function and the miniaturization. The Atmospheric Environment Monitoring Network for city is making up some IR-Remotes and small lidar. It can measure by 3-D environment monitor atmosphere with great area and real time.

Regional Groundwater Quality Monitoring (GQM) in the Upper Vistula River Basin (UVRB) is a pilot scale element of an Integrated Water Management System in SE Poland (about 50,000 km²). The system is currently in the implementation phase. The objectives of the regional GQM network are: (1) to provide data for quality control in regionally important groundwater basins, particularly Major Groundwater Basins (MGWB) in this area; (2) to establish the groundwater vulnerability to large scale diffuse sources of pollution; (3) to perform the prognosis and to identify trends of long time groundwater quality change; (4) to establish the extent of natural and anthropogenic processes impact on groundwater quality. During the sampling of the groundwater monitoring network the Quality Assurance/Quality Control (QA/QC) program for hydrogeochemical measurements was implemented in parallel. The QA/QC program included the collection (using the same equipment as for normal groundwater samples) and analysis (to the same extent as in the normal samples) of additional special samples. The duplicate samples taken from randomly selected GQM sites were used to assess the precision of hydrogeochemical measurements based upon the analysis of variance (ANOVA). The QA/QC program as applied to the GQM in the Upper Vistula River Basin is illustrated in this paper in the examples of two selected trace elements: fluoride (F) and zinc (Zn). Technical variance ((sigma) _tech²) values calculated by means of the classical and robust ANOVA are lower than 20% for the discussed trace elements. This confirms the satisfactory precision of hydrogeochemical measurements.

The Synchronous Scanning Luminoscope (SSL) is a field- portable, synchronous luminescence spectrofluorometer that was developed for on-site analysis of contaminated soil and ground water. The SSL is capable of quantitative analysis of pesticides and explosives using phosphorescence and fluorescence techniques with a high correlation to laboratory data as illustrated by these studies. These techniques allow for rapid field assessments for pesticides and explosives. The Luminoscope is capable of detecting pesticides and explosives to the parts per billion (ppb) range. This paper describes standard field methods for using the SSL and describes the results of field/laboratory testing of explosives and pesticides.

The pattern of responses from a four sensor array have been used for the classification of methanol, propanol, butanol, hexane, heptane and toluene using artificial intelligence (AI) based pattern recognition methods. A feedforward forward network with backpropagation was trained using sensor array data with approximately 300 training vectors and 100 test cases and covering a period of four months. The network consisting of four input nodes, six output nodes, learning rate of 0.1 and momentum of 0 was built using a commercial package (NeuroShell). A classification success rate of 75% was achieved. The bulk of the mis-classifications arose from propanol being classified as butanol and hexane being classified as heptane. These mis-classifications are rational since the respective compounds are very similar in nature. A fuzzy logic algorithm where class membership functions are developed using the mean frequency change and standard deviation of individual sensors was developed for classification of the vapors. In this particular case, classification using the developed fuzzy logic Gaussian algorithm was not as good as the feedforward network with backpropagation, but the Gaussian membership function offers a more rational approach than the previously published trapezoidal membership function.

A process based on a simulation of an industrial float line has been used for deposition of TiO₂ on glass slides. The process is operated at atmospheric pressure rather than under vacuum condition. A variety of organic pre-cursors can be used for TiO₂ formation and films of varying thickness can be produced. Illumination of the TiO₂ coated slides with UVc light had significant anti-microbial effects on Ps.aeruginosa cells in suspension.

Relative to a standard one-foot diameter globe of the Earth the thickness of the atmosphere is comparable to a sheet of plastic food warp covering the globe. Within this thin, fluid membrane long established balances in chemical and radiative processes are being altered by anthropogenic activities. For instance, each year about 50% of the carbon dioxide (CO₂) produced by the combustion of fossil fuels and burning of forests remains in the atmosphere. This 1% yr^-1 increase in CO₂ traps solar energy leading to a rise in atmospheric temperatures known popularly as 'greenhouse warming.' Halocarbons from escaped refrigerants and other sources are destroying the stratospheric ozone layer allowing increased levels of UV to reach the Earth's surface. To monitor these changes in the atmosphere, a global network of atmospheric baseline stations tracks the health of the atmosphere. Some manned stations are in weather challenged locations such as the South Pole, Spitzbergen, Ellesmere Island and the Tibetan Plateau; others are in more benign climates such as Hawaii, Samoa, Tasmania, Reunion, and Kenya. Data from these and others stations are presented and discussed.

The presence of elements even at trace levels can significantly modify the biological/toxicological properties of environmental materials. Among the most sensitive techniques for elemental analysis, ICP-atomic emission spectrometry and ICP-mass spectrometry are commonly used. They have been applied to environmental samples such as air, water, soils and sediments, biological materials, and radionuclides. When coupled with separation methods, they can also be used for the speciation of elements such as As and Se, because the toxicity of these elements depend on their chemical form. Moreover, ICP-AES can be used as an on-line technique for volatile species, e.g. stack monitoring, coal gasification and Be in plant atmosphere, and for liquid streams and solids.