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At least 919 records · Page 51Linked to original sources
PubMed2002

The midgut epithelium of aquatic arthropods: a critical target organ in environmental toxicology.

The midgut epithelium of aquatic arthropods is emerging as an important and toxicologically relevant organ system for monitoring environmental pollution. The peritrophic matrix of aquatic arthropods, which is secreted by the midgut epithelium cells, is perturbed by copper or cadmium. Molecular biological studies have identified and characterized two midgut genes induced by heavy metals in the midgut epithelium. Many other metal-responsive genes (MRGs) await characterization. One of the MRGs codes for an intestinal mucin, which is critical for protecting the midgut from toxins and pathogens. Another codes for a tubulin gene, which is critical for structure and function of the midgut epithelial cells. Perturbation of expression of either gene could condition aquatic arthropod survivorship. Induction of these MRGs is a more sensitive and rapid indicator of heavy-metal pollution than biological assays. Characterization of genes induced by pollutants could provide mechanistic understanding of fundamental cellular responses to pollutants and insight into determinants of aquatic arthropod population genetic structure and survivorship in nature.

Aedes↗
PubMed1975

Respiratory effects in toluene diisocyanate manufacture: a multidisciplinary approach.

A new plant manufacturing toluene diisocyanate (TDI) has provided a unique opportunity to investigate the effects of TDI vapor inhalation on respiratory health in a group of exposed workers who have been studied prior to the start of plant operation. In order to establish dose-response relationships and determine host factors, complete biologic monitoring, including pulmonary function and immunologic studies, has been performed concurrently with a comprehensive environmental monitoring program including continuous sampling for atmospheric concentrations of TDI. Study groups include workers with regular exposure to TDI in production jobs (83), workers with intermittent contact with this vapor, usually in maintenance (28), and a control group of workers employed outside the TDI area (55). This population is being followed for a period of 5 yr. The plant began operations in August 1973 with start-up procedures completed by the end of October. TDI spills occurred for numerous reasons, usually attributed to pump failure and resultant line blockage. Significant exposures also occurred in the drumming operation. The influence of these malfunctions is noted in the continuous monitoring data on atmospheric TDI concentrations which continue to reveal frequent excursions above the threshold limit value (TLV) of 0.02 ppm ceiling. These data are presented in relation to time and plant location. Although the first full year follow-up following initial exposure was not complete, certain preliminary clinical observations were made. A number of workers had episodes of acute respiratory symptoms related to single exposure to an irritant gas at work, usually either TDI or phosgene. It appears that two or three workers in the study population have become "clinically sensitized" to TDI and have been removed from regular TDI exposure. To date, the total number of workers who report the presence of recurring respiratory symptoms has not increased in comparison with the pre-exposure survey. Pulmonary function data after one full year of TDI exposure are not yet available. Pre- and post-shift ventilatory function studies do not indicate significant differences between the exposed and control groups. Selected individuals had carefully controlled inhalation challenge tests to monitored concentrations of TDI vapor under laboratory conditions. In workers suspected of having become "sensitized", immediate and/or late air flow obstruction was demonstrated and could be related to dose of inhaled TDI.

Air Pollutants, Occupational↗
PubMed1997

Specimen banking of marine organisms in the United States: current status and long-term prospective.

A major part of the activities conducted over the last decade by the National Biomonitoring Specimen Bank (NBSB) has involved the archival of marine specimens collected by ongoing environmental monitoring programs. These archived specimens include bivalves, marine sediments, and fish tissues collected by the National Status and Trends and the Exxon Valdez Oil Spill Damage Assessment programs, and marine mammal tissues collected by the Marine Mammal Health and Stranding, Response Program and the Alaska Marine Mammal Tissue Archival Project. In addition to supporting these programs, the specimens have been used to investigate circumpolar patterns of chlorinated hydrocarbon concentrations, genetic separation of marine animal stocks, baseline levels of essential and nonessential elements in marine mammals, and the potential risk to human consumers in the Arctic from anthropogenic contaminants found in local subsistence foods. The NBSB specimens represent a resource that has the potential for addressing future issues of marine environmental quality and ecosystem changes through retrospective analysis; however, an ecosystem-based food web approach would maximize this potential. The current status of the NBSB activities related to the banking of marine organisms is presented and discussed, the long-term prospective of these activities is presented, and the importance of an ecosystem-based food web monitoring approach to the value of specimen banking is discussed.

Animals↗
PubMed2004

Experimental and numerical test of the micrometeorological mass difference technique for the measurement of trace gas emissions from small plots.

Micrometeorological methods for measuring fluxes of gases between the land surface and the atmosphere are non-invasive: in fact, they do not interfere with natural processes of gas exchange. The Micrometeorological Mass Difference (MMD) approach can be used for many environmental monitoring purposes, such as to measure methane and carbon dioxide emission from landfills, methane production by grazing animals, trace gas emission from waste products and from agricultural soils, photosynthesis, and transpiration of plant canopies. The purpose of this study is to adapt the MMD technique, originally developed in Australia, to monitor CO2 and trace gases exchange rate at the plot level. Comparison of different treatments in replicated experiments requires plots of few rather than tens of meters. The tests reported here were performed on a square area (4 m x 4 m) in the meteorological field of the experimental farm of CNR-ISAFOM located in Vitulazio, province of Caserta, Italy (40 degrees 07' N, 14 degrees 50' E, 25 m above sea level) and consisted of the release of pure CO2 at different rates (1.7, 1.3, 0.6 L min(-1)) from a single source on the ground in the center of the experimental area and the consequent measurement of the environmental variables (wind speed and direction, CO2 concentration) at different times at four heights (up to 1.2 m) in order to compute the mass balance according to MMD technique. Measured flow rates well accounted for the mass of CO2 released. A flow underestimation occurred when wind speed dropped below 1.5 m s(-1), in accord with the previous findings obtained in Australia: this happened because anemometers can stall at low speeds, and their measurements are unreliable and because of significant loss of mass from the top of the apparatus. The experimental results were compared with outputs of Computational Fluid Dynamic (CFD) simulations. The commercial CFD package Fluent was used to evaluate performances and sources of errors. According to the experimental and numerical results, the MMD apparatus in our present configuration is suitable to be used for the monitoring of trace gas emissions of experimental plots. Advantages and limits of the present approach are discussed.

Air Pollutants↗
PubMed1999

Estimating maximum concentrations for open path monitoring along a fixed beam path.

Researchers have applied open path optical sensing techniques to a variety of workplace and environmental monitoring problems. Usually these data are reported in terms of a path-average (or path-integrated) concentration. When assessing potential human exposures along a beam path, this path-average value is not always informative, since concentrations along the path can vary substantially from the beam average. The focus of this research is to arrive at a method for estimating the upper-bound in contaminant concentrations over a fixed open beam path. The approach taken here uses a statistical model to estimate an upper-bound concentration based on a combination of the path-average and a measure of the spatial variability computed from point samples along the beam path. Results of computer simulations and experimental testing in a controlled ventilation chamber indicate that the model produced conservative estimates for the maximum concentration along the beam path. This approach may have many applications for open path monitoring in workplaces or wherever maximum concentrations are a concern.

Humans↗
PubMed2007

Climate change affects marine fishes through the oxygen limitation of thermal tolerance.

A cause-and-effect understanding of climate influences on ecosystems requires evaluation of thermal limits of member species and of their ability to cope with changing temperatures. Laboratory data available for marine fish and invertebrates from various climatic regions led to the hypothesis that, as a unifying principle, a mismatch between the demand for oxygen and the capacity of oxygen supply to tissues is the first mechanism to restrict whole-animal tolerance to thermal extremes. We show in the eelpout, Zoarces viviparus, a bioindicator fish species for environmental monitoring from North and Baltic Seas (Helcom), that thermally limited oxygen delivery closely matches environmental temperatures beyond which growth performance and abundance decrease. Decrements in aerobic performance in warming seas will thus be the first process to cause extinction or relocation to cooler waters.

Acclimatization↗
PubMed2004

Recent developments, characteristics, and potential applications of electrochemical biosensors.

The objective of this study is to analyze the technical importance, performance, techniques, advantages, and disadvantages of the biosensors in general and of the electrochemical biosensors in particular. A product of reaction diffuses to the transducer in the first generation biosensors (based on Clark biosensors). The mediated biosensors or second generation biosensors use specific mediators between the reaction and the transducer to improve sensitivity. The second generation biosensors involve two steps: first, there is a redox reaction between enzyme and substrate that is reoxidized by the mediator, and eventually the mediator is oxidized by the electrode. No normal product or mediator diffusion is directly involved in the third generation biosensors, direct biosensors. Based on the type of transducer, current biosensors are divided into optical, mass, thermal, and electrochemical sensors. They are used in medical diagnostics, food quality controls, environmental monitoring, and other applications. These biosensors are also grouped under two broad categories of sensors: direct and indirect detection systems. Moreover, these systems could be further grouped into continuous or batch operation. Therefore, amperometric biosensors and their current applications are focused on more in detail since they are the most commonly used biosensors in monitoring and diagnosing tests in clinical analysis. Problems related to the commercialization of medical, environmental, and industrial biosensors as well as their performance characteristics, their competitiveness in comparison to the conventional analytical tools, and their costs determine the future development of these biosensors.

Biosensing Techniques↗
PubMed1994

The radioanalytical laboratory at Pelindaba. Some applications for environmental and health monitoring.

This article deals with the radioanalytical work performed at Pelindaba, Atomic Energy Corporation of South Africa. It reports on the activities of a commercial laboratory, employing analytical techniques, such as total alpha/beta counting, alpha spectrometry, liquid scintillation counting, gamma spectrometry, and neutron activation analysis. Techniques discussed in more detail include semicyclic activation analysis for the determination of fluorine in vitamin mixes, as well as the determination of uranium and radium in urine samples for personnel monitoring.

Environmental Monitoring↗
PubMed1997

EROD and CYP1A protein in channel catfish (Ictalurus punctatus) from an urban estuary relative to that in benzo[a]pyrene-exposed hatchery specimens.

Bottom-feeding fish such as flounder and killifish have been widely used in monitoring hepatic monooxygenase induction in polluted water bodies. While channel catfish are often utilized in tissue monitoring of fresh and estuarine water bodies, few data are available on their use in environmental monitoring of hepatic monooxygenase activity. In this project, the presence of CYP1A protein was verified in channel catfish through recognition by Mab 1-12-3, an antibody which recognizes the CYP1A homologue in a variety of teleost species. CYP1A protein levels and 7-ethoxyresorufin-o-deethylase (EROD) activity in laboratory control and benzo-a-pyrene (BaP)-challenged channel catfish were compared to those in feral channel catfish from Back River, an urban estuarine tributary to Chesapeake Bay. Though more variable, mean CYP1A protein levels in the field-collected fish were similar to those of the BaP-induced laboratory fish. However, EROD activity of the Back River fish was less than one half that observed in the BaP-induced laboratory fish. When normalized to CYP1A protein levels, EROD activity was slightly lower in the Back River fish than either the laboratory control or BaP-treated fish. This finding may indicate possible inhibition or inactivation of the CYP1A protein in the feral fish.

Journal Article↗
PubMed1999

Determination of chemical warfare agent degradation products at low-part-per-billion levels in aqueous samples and sub-part-per-million levels in soils using capillary electrophoresis.

A significant enhancement in the method detection limits is observed in the analysis of chemical warfare agent (CWA) degradation products in environmental samples by capillary electrophoresis (CE) using electrokinetic injection. The CE method uses indirect UV detection of the nonderivitized acidic analyte and a cationic surfactant, didodecyldimethylammonium hydroxide, for reversal of the electroosmotic flow. Analytes studied include the dibasic acid methylphosphonic acid (MPA) and its monoacid/monoalkyl esters, RMPA, where R = ethyl, isopropyl, and pinacolyl (2-(3,3-dimethylbutyl)). The CE method uses an attractive buffer system which is highly stable and inexpensive, and, in addition to reversing the electroosmotic flow, provides excellent separation efficiencies within a 3-min run. This CE method is also free from interference caused by carbonate, humic acids, and fluoride. Compared to pressure injection, electrokinetic injection with this CE buffer system provided substantially lower detection limits, up to 100-fold lower for samples in reagent water. However, to best realize the benefits of the electrokinetic injection enhancement for environmental samples, a prior cleanup of the sample using standard ion-exchange cartridges is necessary. This cleanup step uses sequential cartridges to remove sulfate (barium cartridge), chloride (silver cartridge), and cations (H+ cartridge). Using this approach, detection limits for these four acids were as low as 1-2 micrograms/L for water samples and 25-50 micrograms/L for aqueous leachates of soil samples (10 mL of leachate/1.5 g of soil). The utility of this method for separation of CWA degradation products by CE is discussed in terms of pressure injection versus electokinetic injection. The effects of voltage and time of injection on the separation were investigated. Results from three types of soils and four types of water (groundwater, artificial seawater, tap water, bay water) indicated that the method has potential for environmental monitoring. Quantitative CE analysis with electrokinetic injection enhancement of detection limits of these types of environmental samples requires the use of an appropriate internal standard approach. The data presented here indicate that an internal standard-based approach could be expected to give analysis results in the sub-part-per-million concentration range of 90-110% of the true value.

Biodegradation, Environmental↗
PubMed1996

Identification and screening evaluation of key historical materials and emission sources at the Oak Ridge Reservation.

In 1991, the State of Tennessee initiated a Health Studies Agreement with the U.S. Department of Energy. It included independent studies of possible adverse health effects in people living near the Oak Ridge Reservation resulting from releases of chemicals and radionuclides since 1942. A Dose Reconstruction Feasibility, the first of a planned sequence of initiatives to evaluate the potential for health effects, included application of screening methods to focus subsequent dose reconstruction and epidemiologic efforts on the materials and emission sources that have historically been most important. The feasibility study produced a history of operations that likely generated off-site releases from the X-10, K-25, Y-12, and S-50 plants, based on reviews of classified and unclassified records and interviews of active and retired workers. The availability of environmental monitoring and research data that would support dose reconstruction was also characterized. Quantitative emission and environmental contamination data were used to identify those materials and plant activities that should receive the highest priority in further health studies. Plausible exposure pathways were identified, and screening methods were used to identify the most important pathways and past activities that appear to be associated with the greatest health hazards. The materials and activities shown to have the highest potential for public health hazards are as follows: 1) The release of radioiodine [likely over 3.7 PBq (100,000 Ci)] to the air from radioactive lanthanum ("RaLa") processing at X-10 (now Oak Ridge National Laboratory) from 1944 through 1956; 2) The release of 137Cs and other radionuclides in liquid wastes from chemical separation activities at X-10; 3) The release of mercury to the air, soil, and surface waters from Y-12 lithium enrichment operations between 1950 and 1963. About 11,000,000 kg of mercury were handled at Y-12, and 910,000 kg were reported lost or unaccounted for; and 4) The release of polychlorinated biphenyls (PCBs) from machining oils, electrical equipment, and other sources in the Oak Ridge area. Based on the findings of the study, the Oak Ridge Health Agreement Steering Panel called for a dose reconstruction for radioiodine, mercury, PCBs, and radionuclides released from White Oak Creek and research into opportunities for analytic epidemiologic studies to identify adverse health effects in exposed populations.

Air Pollutants, Radioactive↗
PubMed2001

Environmental and biological monitoring of occupational exposure to organic micropollutants in gasoline.

An exposure risk assessment of workers in a refinery production unit was undertaken. Gasoline and its main components were investigated through environmental and biological monitoring. Measured variables were environmental benzene, toluene, pentane and hexane; benzene and toluene in blood and urine; tt-MA (metabolite of benzene) in urine. Multivariate statistical analysis of the data showed that worker's exposure to the above substances fell within the limits specified by organisations such as ACGIH. Also, biological values complied with reference values (RV) for non-occupationally-exposed population. Different values of biological variables were determined by separating smokers from non-smokers: smokers had hematic and urinary benzene values significantly higher than non-smokers. During a 3-yr sampling, it was possible to identify a significant decrease of benzene in the workplace air and of hematic benzene for non-smokers. The most exposed department, one in which tank-lorries were loaded, needs further investigation and extended monitoring.

Adult↗
PubMed2004

Rapid assessment of polycyclic aromatic hydrocarbon (PAH) exposure in decapod crustaceans by fluorimetric analysis of urine and haemolymph.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous and potentially harmful contaminants of the coastal and marine environment. Studies of their bioavailability, disposition and metabolism in marine organisms are therefore important for environmental monitoring purposes. Detecting PAH compounds in the biological fluids of marine organisms provides a measure of their environmental exposure to PAHs. In the present study, the shore crab Carcinus maenas was exposed to waterborne pyrene for 48h. Urine and haemolymph samples were analysed by direct fluorimetry utilising both fixed wavelength (FF) and synchronous scanning fluorescence (SFS) techniques. Samples from exposed crabs exhibited fluorescence due to 1-OH pyrene equivalents, whilst samples from control crabs did not. Levels of equivalents were exposure dependent. Urine was shown to be a more suitable medium for the analysis of PAH equivalents. In a separate experiment, depuration of pyrene equivalents in urine was monitored over time. Urinary levels reached a maximum 2-4 days after initial exposure and decreased steadily thereafter. No unchanged parent pyrene was detected in samples from exposed crabs. While fluorimetric techniques could discriminate between 1-OH pyrene equivalents and parent pyrene, identification of specific metabolites was only possible with HPLC/F analysis. This revealed crabs had bio-transformed pyrene into 3 major conjugates of 1-OH pyrene, which were excreted in the urine. While such biotransformation of PAH is well documented in fish and several crustaceans, this is the first study to use direct fluorimetry to detect PAH equivalents in exposed crustacean urine. Fluorimetric results correlated well with those obtained by HPLC/F and ELISA techniques. The technique has great potential as a rapid, inexpensive and non-destructive technique for field biomonitoring of PAH exposure in crustaceans.

Analysis of Variance↗
PubMed2000

Activation of the hsp70 promoter by environmental inorganic and organic chemicals: relationships with cytotoxicity and lipophilicity.

Stress proteins (heat shock proteins, HSPs) have been proposed as general markers of cellular aggression and their use for environmental monitoring is often suggested. The aim of this work was to study the potency of various environmentally relevant organic and inorganic chemicals to induce the expression of the HSP70 marker. For this purpose, we used an established HeLa cell line containing the chloramphenicol acetyl transferase (CAT) gene under the control of the hsp70 promoter. The screening of three metallic and 15 organic chemicals revealed differences in their capacities to induce the hsp70 promoter. The three metals tested (cadmium, zinc and mercury) were able to induce a stress response. Some organochlorine compounds (chlorophenol derivatives, tetrachlorohydroquinone, 3, 4-dichloroaniline, ethyl parathion and 1-chloro-2,4-dinitrobenzene) induced a response, whereas other common halogenated pesticides or aromatic hydrocarbons (e.g. benzo(a)pyrene, 2, 4-dichlorophenoxyacetic acid, endosulfan, diuron, 4-nonylphenol) did not. The potency to induce hsp70 was significantly correlated to the octanol-water partition coefficient (log K(ow)) of the inducing chemicals, except for 1-chloro-2,4-dinitrobenzene and ethyl parathion. Cytotoxicity assays run in parallel to the induction measurements revealed that the three metals were effective at non cytotoxic doses whereas all organic compounds, except tetrachlorohydroquinone and 1-chloro-2,4-dinitrobenzene, induced the promoter at cytotoxic doses. These results suggest that hsp70 is induced by different mechanisms of toxicity. We propose that this model can be used in mechanistic studies for the detection of toxic effects of certain pollutants.

Cadmium↗
PubMedDate not supplied

[Ontogenesis and population: evaluation of developmental stability in natural populations].

Ontogenetic and population studies traditionally develop independently. At the same time, the relevance of specific analysis of a specimen as ontogenesis for both correct assessment of populations and their dynamics in time and space and understanding the mechanisms underlying population processes is becoming more and more clear. Developmental stability serves as the most general description of the developing organism status. The level of developmental noise commonly evaluated by fluctuating asymmetry is the main index of developmental stability. High developmental stability is maintained on the basis of genetic coadaptation under optimal developmental conditions. Coordinated changes in developmental stability and other homeostatic indices, including genetic, physiological, biochemical, and immune indices suggest that we consider the general status of the organism by evaluating its developmental stability. Evaluation of developmental stability as a measure of environmental stress, apparently, is the most promising. In practical terms, this allows us to evaluate and monitor environmental health under both natural and various anthropogenic conditions. Outlooks of this approach as relates to studies of developmental stability are discussed.

Adaptation, Physiological↗
PubMedDate not supplied

[The importance of monitoring legionellosis in hospital setting: the case of a Sicilian Hospital].

Hospital-acquired legionellosis is a major problem. In Italy this issue is still underestimated because the reported figures are lower than the actual cases. This is probably due to a lack of diagnosis and monitoring. In Sicily, no cases of hospital-acquired legionellosis were reported in the last few years. In the year 2001, a reference laboratory was set up to help health authorities monitor and prevent hospital-acquired legionellosis. The authors report the data concerning a measure of environmental monitoring and water treatment carried out in a hospital where no legionellosis was ever detected before.

English Abstract↗
PubMed2004

Monitoring ground-level air for trace analysis: methods and results.

Trace analysis enables the sensitive detection of radionuclide concentrations in ground-level air in the range of microbecquerel per cubic meter (microBq m(-3)). Typical sampling intervals of less than one day up to a few days can be used in routine operation. Trace analysis measurements are performed in the framework of the German Integrated Measuring and Information system (IMIS) and the International Monitoring System (IMS) used for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Within the environmental monitoring programmes of the German IMIS the Federal Office for Radiation Protection (BfS) performs measurements of aerosol-bound radionuclides and of radioactive noble gases in the atmosphere. Aerosols are collected on filters with high-volume air samplers and analysed by gamma-spectrometry, alpha-spectrometry, and integral measurements of beta-activity, with preceding radiochemical separation. Noble gas samples from 15 sites world-wide are analysed to observe the (85)Kr-release from nuclear fuel reprocessing plants and from seven sites in Germany to monitor the (133)Xe emitted from nuclear power plants. As part of the International Monitoring System (IMS) of the CTBT an automatic aerosol sampling and measuring system and an automatic noble gas sampling and measuring system will be operated by the BfS at Mount Schauinsland near Freiburg. Because of its expertise in noble gas measurements the BfS had been chosen to perform an intercomparison experiment in the BfS laboratory in Freiburg with several automatic noble gas sampling and measurement systems before their installation at IMS sites. To establish quality-assurance programmes for trace analysis performed for the German IMIS close collaboration between the involved German institutions has been established. First steps have been taken to expand cooperation to other European laboratories. Informal data exchange already occurs between trace-analysis laboratories in Europe (Ring of Five) and helps in cases of enhanced activity concentrations to get a rapid overview of the radiological situation and to identify possible sources.

Journal Article↗
PubMed2002

Direct mass spectrometric measurement of gases in soil monoliths.

An integrated approach to gas analysis in soil cores was conducted to provide a novel method for observing the gas dynamics associated with upland soil ecosystems. Depth profiles of the O(2), Ar, CO(2), CH(4), N(2) and NO(x) concentrations in intact soil monoliths were obtained simultaneously using membrane inlet mass spectrometry (MIMS). This technique enables the direct measurement of multiple gas species throughout the soil core with minimal disturbance. Depth profiles provided data on the vertical heterogeneity of gas concentrations, while horizontal heterogeneity was monitored by comparison between profiles. Detailed descriptions of the modifications to current MIMS methods for in situ environmental monitoring of terrestrial soils are provided. These included a thorough examination of calibration of the MIMS probe in gas phase, stirred and unstirred H(2)O, or between glass beads immersed in H(2)O. Calibration was also carried out in sterile (autoclaved) soil. The mean concentrations of CO(2) and CH(4) in the soil monoliths increased from 27 microM and undetectable levels respectively at the surface, to maximum values of 3.6 mM and 4.3 microM at 12-cm depth. These changes corresponded with decreases in mean O(2), Ar and N(2) concentration from 300, 20 and 720 microM respectively to 0-6, 10 and 574 microM at 12-cm depth. These data indicated the presence of a gradient within the core from an aerobic environment to an O(2)-depleted, but not in all cases a completely anaerobic, one. This transition corresponded, to some extent, with that between the upper and lower soil horizons. The increased methane and CO(2) concentrations observed at depth are indicative of anaerobic environments. General trends associated with the gradually changing vertical heterogeneity of these gas profiles and the transition towards anaerobiosis did not provide evidence for the existence of localised microsites. Some evidence for microsite-specific microbial communities was however, provided by observation of broad zones of accumulation of NO(x) species, but only at concentrations close to the limit of detection of the method. The ratio of each gas, to argon was calculated at each depth. This was done to correct for physical parameters, which influence inert and biologically active gases, equally. The amount of di-nitrogen as a ratio to Ar was seen to increase with depth. This could be evidence for denitrification in the lower horizon. An example of the dynamic 'online' data collection capabilities is provided for diurnal oscillations in subsurface (5 cm) soil gas concentrations.

Gases↗