Time Variation Of Concentration Research Articles

Diurnal variations of gaseous and particulate nitrophenol isomers in the atmosphere monitored by using wet scrubbing online preconcentration

Gas- and particle-phase nitrophenols are collected separately and preconcentrated for HPLC analysis. Time variations in concentrations and partitioning into particles of nitrophenols are obtained with a resolution of 2 h.

A finite element method for environmental and pollutant transport prediction

In the last decades, significant researches were dedicated to model the water-quality trends, soil erosion and material losses, contaminant transport, and their ecological impacts. The present paper investigates theoretically and presents a numerical model with finite elements of the pollutant transport and diffusion in 2-D environmental flow. It is a general model based on the physical groundwater flow equations presented into a new approach, in quantity structure. The mathematical model is based on mass conservation, including the main flow of the fluid and existing pollutants. The fluid mass conservation includes the changes in the groundwater volume flow in a selected time interval and the appeared modifications in the aquifer characteristics due to the pollutant presence are used in the numerical model. Some supplementary considerations concerning mathematical modeling are briefly presented. This model can be used to simulate the groundwater behavior in different situations, with a concentrated source of the pollutant, or with 2 sources of pollution. In the present paper are simulated only the aquifers with mainly horizontal groundwater flow and with a relatively known aquifer’s structure. The model is tested for a landfill near the Dambovita River, to predict the groundwater contamination and the time variation of concentration. Finally, some conclusions and references are presented.

2005–2017 ozone trends and potential benefits of local measures as deduced from air quality measurements in the north of the Barcelona metropolitan area

Abstract. We analyzed 2005–2017 data sets on ozone (O3) concentrations in an area (the Vic Plain) frequently affected by the atmospheric plume northward transport of the Barcelona metropolitan area (BMA), the atmospheric basin of Spain recording the highest number of exceedances of the hourly O3 information threshold (180 µg m−3). We aimed at evaluating the potential benefits of implementing local-BMA short-term measures to abate emissions of precursors. To this end, we analyzed in detail spatial and time variations of concentration of O3 and nitrogen oxides (NO and NO2, including OMI remote sensing data for the latter). Subsequently, a sensitivity analysis is done with the air quality (AQ) data to evaluate potential O3 reductions in the north of the BMA on Sundays compared with weekdays as a consequence of the reduction in regional emissions of precursors. The results showed a generalized decreasing trend for regional background O3 as well as the well-known increase in urban O3 and higher urban NO decreasing slopes compared with those of NO2. The most intensive O3 episodes in the Vic Plain are caused by (i) a relatively high regional background O3 (due to a mix of continental, hemispheric–tropospheric and stratospheric contributions); by (ii) intensive surface fumigation from mid-troposphere high O3 upper layers arising from the concatenation of the vertical recirculation of air masses; but also by (iii) an important O3 contribution from the northward transport/channeling of the pollution plume from the BMA. The high relevance of the local-daily O3 contribution during the most intense pollution episodes is clearly supported by the O3 (surface concentration) and NO2 (OMI data) data analysis. A maximum decrease potential (by applying short-term measures to abate emissions of O3 precursors) of 49 µg O3 m−3 (32 %) of the average diurnal concentrations was determined. Structurally implemented measures, instead of episodically, could result in important additional O3 decreases because not only the local O3 coming from the BMA plume would be reduced, but also the recirculated O3 and thus the intensity of O3 fumigation in the plain. Therefore, it is highly probable that both structural and episodic measures to abate NOx and volatile organic compound (VOC) emissions in the BMA would result in evident reductions of O3 in the Vic Plain.

Hydrogeochemical earthquake precursor in the southern Baikal region

This paper presents the results of study of seismically induced variations in helium concentration in groundwater in the southern Baikal region. Unlike previous studies, data were obtained not only in Baikal deepwater but also in artesian wells in the southern Baikal region. The correlation coefficients between the data obtained at these observation stations, indicator functions, and an integrated indicator functions were calculated. They provide an objective assessment of time variations in concentrations due to changes in the stress-strain state of the Earth’s crust related to earthquake preparation and hence permit one to predict the time of an earthquake.

Study of boundaries equilibrium in a shallow solar pond

Abstract. One-dimensional mass and heat transfer models have been provided to find salinity and temperature gradients in a gradient layer of a solar pond. Using finite difference method (FDM), heat and mass transfer differential equations were discretized by Crank - Nicolson scheme. The present study is based on the experimental data of a solar pond in Ferdowsi University of Mashhad, obtained in a period of 126 days from May to September 1999. Increase in concentration and temperature gradient, cause increase and decrease in stability, respectively. Time variations of concentration and temperature gradients are affect the dynamic stability and equilibrium of upper and lower boundaries of the solar pond. The equilibrium of the upper and lower boundaries has been compared using Neilson equilibrium boundary criterion. The numerical data of the lower boundary were far from dynamic instability. Those data had good agreement with the Neilson equilibrium boundary criterion. The dynamic stability of the upper boundary was maintained with time, but the numerical data of the upper boundary were not in keeping with the Neilson equilibrium boundary criterion. Therefore the lower boundary has with time, behaved with more equilibrium towards the upper boundary.

One-year time variations of anthropogenic radionuclides in aerosols in Tokyo after the Fukushima Dai-ichi Nuclear Power Plant reactor failures

We report on the results of monitoring of environmental radiation for one year (13 March 2011 to 12 March 2012), including air dose rates and the concentrations of radionuclides in aerosols in Tokyo, after the reactor failures at the Fukushima Dai-ichi Nuclear Power Plant. The air dose rates began to increase at 4:00–5:00 JST on 15 March 2011, and the maximum rate was observed at 10:00–11:00 JST. Two peaks were observed before 23 March 2011, and then the air dose rates decreased until March 2012. The time variations of concentrations of radionuclides in aerosols showed tendencies similar to those of air dose rates. Short-lived radionuclides (99Mo (99mTc), 129mTe (129Te), 131mTe, 132Te (132I), 133I and 136Cs) were under the detection limit during April 2011. Iodine-131 was detected until early June 2011, and long-lived radionuclides (134Cs and 137Cs) were detected intermittently for one year. Based on our results, gamma doses and committed effective doses resulting from inhalation were estimated.

Variation of charge in acoustoplasma during the period of modulation of the discharge current

We investigate dynamic parameters of acoustoplasmic discharge associated with the time variation of concentration of charge carriers. Instantaneous values of the difference in currents measured by the anode and cathode are determined depending on the frequency of modulation of the discharge current. The volt-coulomb characteristics of acoustoplasmic discharge are also measured. The observed jump of the charge at gradual variation of the voltage on the discharge tube can be considered as a phase transition in acoustoplasma.

Space and time variations in concentrations of biogenic and organic matter and phytoplankton in the water of the Selenga River and its delta branches

Specific features of the concentration dynamics of biogenic substances, organic C, and phytoplankton in the lower reaches of the Selenga and its delta branch are identified. The quantitative and qualitative changes in these components are demonstrated for the conditions of extremely low water abundance. High correlation was shown to exist between variations of the concentrations of nitrate N, mineral P, and phytoplankton biomass.

Data assimilation in meteorological pre-processors: Effects on atmospheric dispersion simulations

In previous work [Kovalets, I., Andronopoulos, S., Bartzis, J.G., Gounaris, N., Kushchan, A., 2004. Introduction of data assimilation procedures in the meteorological pre-processor of atmospheric dispersion models used in emergency response systems. Atmospheric Environment 38, 457–467.] the authors have developed data assimilation (DA) procedures and implemented them in the frames of a diagnostic meteorological pre-processor (MPP) to enable simultaneous use of meteorological measurements with numerical weather prediction (NWP) data. The DA techniques were directly validated showing a clear improvement of the MPP output quality in comparison with meteorological measurement data. In the current paper it is demonstrated that the application of DA procedures in the MPP, to combine meteorological measurements with NWP data, has a noticeable positive effect on the performance of an atmospheric dispersion model (ADM) driven by the MPP output. This result is particularly important for emergency response systems used for accidental releases of pollutants, because it provides the possibility to combine meteorological measurements with NWP data in order to achieve more reliable dispersion predictions. This is also an indirect way to validate the DA procedures applied in the MPP. The above goal is achieved by applying the Lagrangian ADM DIPCOT driven by meteorological data calculated by the MPP code both with and without the use of DA procedures to simulate the first European tracer experiment (ETEX I). The performance of the ADM in each case was evaluated by comparing the predicted and the experimental concentrations with the use of statistical indices and concentration plots. The comparison of resulting concentrations using the different sets of meteorological data showed that the activation of DA in the MPP code clearly improves the performance of dispersion calculations in terms of plume shape and dimensions, location of maximum concentrations, statistical indices and time variation of concentration at the detectors locations.

RUNOFF OF METALS FROM ALUM‐TREATED HORSE MANURE AND MUNICIPAL SLUDGE1

ABSTRACT: Land application of organic soil amendments can increase runoff concentrations of metals such as Fe and Zn, metalbids such as B and As, and non‐metals such as P and S that have the potential for causing adverse environmental impacts. Aluminum sulfate, or alum (Al2(SO4)3*(14H2O), can reduce concentrations of some materials in runoff from sites treated with organic amendments. The objectives of this study were to (a) quantify concentrations of selected constituents (Al, As, B, Ca, Cd, Co, Fe, K, Mg, Mn, Mo, Na, P, Pb, 5, Se, Ti, and Zn) in runoff from plots treated with horse manure (mixed with stall bedding) and municipal sludge, (b) assess runoff quality effects of alum addition to those treatments, and (c) determine time variations in concentrations of the constituents. Horse manure and municipal sludge were applied to twelve 2.4 by 6.1 m fescue plots (six each for the manure and sludge). Alum was added to three of the manure‐treated and three of the sludge‐treated plots. Simulated rainfall (64 mm/h) was applied to the 12 treated plots and to three control (no treatment) plots. The first 0.5 h runoff was sampled and analyzed for the constituents described above. Addition of manure or sludge had no effect on runoff concentrations of the majority of constituents. In some cases (e.g., Al, As, Fe, Zn), however, concentrations were near or in excess of threshold values recommended for marine wildlife protection. Alum addition increased runoff of Al, Ca, K, and 5, due likely to its composition and by the addition of lime to counteract the acidity of alum. Concentration decreases of more than 50 percent were noted for P for the horse manure treatment. No alum effect was detected for P in runoff from the sludge‐treated plots, possibly due to relatively stable P forms in the sludge. Runoff concentrations of Al, As, Fe, K, Mn, and P followed an approximately first‐order decline with respect to time. Runoff concentrations of Ca and 5, however, peaked during the second runoff sample (four minutes following initiation of runoff), suggesting that differences in mobility and/or transport mechanisms exist among the materials investigated.

QUALITY OF RUNOFF FROM PLOTS TREATED WITH MUNICIPAL SLUDGE AND HORSE BEDDING

Land application of horse stall bedding and municipal sludge can increase runoff concentrations of nutrients,organic matter, and bacteria as well as steroidal hormones such as estrogen. Concentrations of materials in runoff fromsites treated with animal manure can be reduced by aluminum sulfate, or alum [Al2(SO4)314H2O] treatment. Theobjectives of this study were to assess plots treated with horse stall bedding or municipal sludge for: (a) runoff quality[concentrations of nitrate nitrogen (NO3-N), ammonia nitrogen (NH3-N), orthophosphate-phosphorus (PO4-P), fecalcoliform (FC), chemical oxygen demand (COD) and 17- estradiol (17 -E, a form of estrogen)]; (b) changes in runoffquality caused by alum treatment; and (c) time variations in concentrations of the analysis parameters. Horse beddingand municipal sludge were applied to twelve 2.4 6.1 m fescue plots (six each for the bedding and sludge). Three of thebedding-treated and three of the sludge-treated plots were also treated with alum. Simulated rainfall (64 mm/h) wasapplied to the 12 treated plots and to three control (no treatment) plots. The data were analyzed as originating fromseparate completely randomized, one-way designs with three replications of each treatment. The first design had treatmentlevels of bedding, bedding and sludge, and control, while the second design had treatment levels of sludge, sludge andalum, and control. The control data were common to both designs. The first 0.5 h runoff was sampled and analyzed for theparameters described above. Analysis parameter concentrations for the waste treated plots were generally lower thanthose previously reported for runoff after organic treatments. In some cases, concentrations were no different from thecontrols. Mass losses of all parameters were low and agronomically insignificant. Alum addition decreased runoff PO4-Pconcentrations and increased NO3-N concentrations but had no effect on concentrations of other parameters. Asignificant effect of alum addition on 17 -E and COD concentrations was anticipated on the basis of previous studies; itsabsence might have been due to inadequate mixing or interval between addition and simulated rainfall. Relationshipsbetween concentration and collection time followed two patterns: (a) highest concentrations occurring during the firstsample (two minutes following runoff initiation; NO3-N, COD, FC and 17 -E) and (b) delay in peak concentration untilfour minutes following runoff initiation (NH3-N and PO4-P). The detection of different general relationships betweenconcentration and time suggests that different mechanisms are dominant in transport of the parameters analyzed.

Polychlorinated biphenyl equilibria in an estuarine system

The stability of the partition of polychlorinated biphenyl (PCB) congeners between water and the compartments of particulate matter (seston), surface sediment, net-plankton and mussels has been investigated for 1.5 years. Samples were regularly obtained from four stations, representing River Rhine, brackish and saline estuarine and stagnant saline conditions. In spite of the PCB gradients, from freshwater to seawater, and time variations in concentrations, the partition coefficients K d (distribution coefficients) were very stable for each of the congeners. This demonstrates that the partition between water and the other compartments is due to processes which reach their equilibrium within weeks, independent of the local variations in concentrations. This confirms the non-foodchain accumulation concept of Schneider [1] for aquatic organisms.

The along-wind diffusion of the tracer cloud in finite release experiments.

The along-wind elongation of the tracer plume was observed in the medium-range atmospheric diffusion experiments with finite release time of air tracer substance. Since the elongated portion of a detached plume pursues the same course in the treatment of along-wind diffusion as an instantaneous puff, the along-wind diffusion parameter σx was estimated from the time variation of concentration in the elongated portion of the detached plume. This was compared with σx from other equivalent range experiments after grouping under stable, near neutral, and unstable classifications of atmospheric stability. In stable condition, a slight tendency to smaller σx values was recognized, but distinct dependency of σx growth on stability was not observed. Furthermore, consideration was taken of the valuation of time average concentration relating to the tracer release time, sampling time, and total time of tracer cloud passage. The method of evaluating the average concentration was considered, and it was made clear that the method was available for any sampling mode.

Fine particle residential indoor air pollution

Indoor-generated elemental constituents of fine aerosol particulate matter may be distinguished from constituents infiltrating from the outdoors by comparing time variation in concentrations on an hourly basis. Measurements within three residential buildings indicate that sulfur and lead-bromine aerosols are predominantly of outdoor origin, although a secondary indoor lead source was detected. Potassium is, to a significant degree, of indoor origin. Indoor-outdoor exchange times inferred for fine particle constituents are in agreement with those estimated for gas exchange and with model calculations, suggesting conservative fine aerosol transport. However, coarse particle constituents e.g., iron, exhibit time variability complicated by nonconservative behavior, such as removal by filtration and settling. The experimental techniques used in this study, time sequence filter sampling of aerosols and elemental analysis by PIXE, are generally applicable to studies of the indoor working, as well as living, environments.

Application of Proton Induced X-Ray Emission Analysis to the St. Louis Regional Air Pollution Study

AbstractThe St. Louis aerosol was sampled during the period 16-22 August 1973 simultaneously at two locations using cascade impactors for sequential 12-hour samples. The six particle size fractions of each sampling were individually analyzed using PIXE for elements from S to Br and beyond and for heavy elements including Pb which permitted time variations of concentrations and particle size distributions to be followed and related to meteorological changes during the sampling period. In addition, the data were compared with average levels of the elements in coastal north Florida and maritime Bermuda as well as at a third St. Louis site. From this it appeared that some of the concentrations in St. Louis were at natural levels whereas others appeared to be higher and linked to air pollution sources. These relationships and others in this study may lead to criteria for distinguishing between pollutants and natural background in urban aerosols.

Preferential uptake of sulphone by affected skin tissue of leprosy patients as detected by a tracer method.

DIAMINO-DIPHENYL-SULPHONE and a number of its derivatives have been found to be very effective in the treatment of leprosy ; but the exact mode of their action on the affected tissue and invading Mycobacterium has not yet been definitely established1–3. In the present work, diamino-diphenyl-sulphone labelled with sulphur-35 was used for studying the time variation of concentration of the drug in blood and healthy and diseased skin tissues of the leprosy patients. An interesting observation was that the drug was found to be localized to a greater extent in the affected tissues compared to healthy ones. Such studies were not possible with the help of earlier colorimetric techniques4, as these required tissues in bulk. The method used here was found to be ten times more sensitive than the colorimetric techniques.