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1.
Ozonation of seawater from different locations: formation and decay of total residual oxidant--implications for ballast water treatment 总被引：3，自引：0，他引：3
Ballast water is a likely cause for worldwide transfer of non-indigenous aquatic species because of the large volumes and frequency of possible inoculations. Ozone is one treatment option being considered for eliminating non-indigenous species in ballast water. When ozone is applied to seawater, secondary disinfectants are formed, commonly measured and expressed as total residual oxidant (TRO). The goal of this study was to determine those variables most likely to affect the rate of TRO increase during ozonation and the subsequent TRO decline that occurs over time. These parameters strongly influence the efficacy of ozone treatments aimed to eliminate organisms present in ballast water. Seawater was obtained from Puget Sound, Washington; Cape Fear, North Carolina; and San Francisco Bay. Results indicated that seawater characteristics, including the organic content and ammonia, affect the amount of ozone required to achieve a desired TRO level and rate of TRO decay, and therefore need to be considered in determining ozone requirements for ballast water treatment. 相似文献
2.
Summary A steady-state mean meridional model of the stratosphere is used to investigate the effects of water vapour and nitrogen oxides on ozone and temperature distributions in the stratosphere. The Chapman classical photochemical scheme for ozone is extended to include the dominant reactions involving hydrogen compounds and nitrogen oxides. The ozone and temperature changes are studied under radiative-photochemical equilibrium conditions and in a model incorporating both transport and radiative-photochemical processes. It is found that both hydrogen and nitrogen reactions contribute to substantial decreases in ozone and temperature under photochemical equilibrium conditions, but the computed distribution do not resemble those observed. The effect of transport processes is to reduce the deviations in the ozone mixing ratio and temperature with the computed distributions having many features in common with the observations. It is found that the ozone and temperature respond more readily to the arbitrary increase of nitrogen oxides than to that of water vapour. 相似文献
3.
Craig L. Patterson Fernando Cadena Rajib Sinha Dzung Kim Ngo‐Kidd Abbas Ghassemi E. Radha Krishnan 《Ground Water Monitoring & Remediation》2013,33(2):44-52
Methyl‐tertiary butyl ether (MTBE) is often found in groundwater as a result of gasoline spills and leaking underground storage tanks. An extrapolation of occurrence data in 2008 estimated at least one detection of MTBE in approximately 165 small and large public water systems serving 896,000 people nationally (United States Environmental Protection Agency [U.S. EPA] 2008). The objective of this collaborative field study was to evaluate a small groundwater treatment system to determine the effectiveness of ultraviolet (UV)/ozone treatment in removing MTBE from contaminated drinking water wells. A pilot‐scale advanced oxidation process (AOP) system was tested to evaluate the oxidation efficiency of MTBE and intermediates under field conditions. This system used ozone as an oxidizer in the presence of UV light at hydraulic retention times varying from 1 to 3 min. MTBE removal efficiencies approaching 97% were possible with this system, even with low retention times. The intermediate t‐butyl alcohol (TBA) was removed to a lesser extent (71%) under the same test conditions. The main intermediate formed in the oxidation process of the contaminated groundwater in these studies was acetone. The concentrations of the other anticipated intermediates t‐butyl formate (TBF), isopropyl alcohol (IPA), methyl acetate (MAc), and possible co‐occurring aromatics (BTEX) in the effluent were negligible. 相似文献
4.
Summary The total ozone response to strong major geomagnetic storms (Ap≥60) in winter along the 50° N latitudinal circle is studied. The results add to the recent results of Laštovička et al. (1992)
obtained for European middle latitudes (∼50°N) and to the results of Mlch (1994). A significant response of total ozone is
only observed in winter under high solar activity/E-phase of QBO conditions (E-max) and seems to be caused by geomagnetic
storm-induced changes of atmospheric dynamics. There are two sectors along latitude 50°N, which are sensitive to forcing by
geomagnetic storms both in total ozone and the troposphere — north-eastern Atlantic-European and eastern Siberia-Aleutian
sectors. The total ozone response under E-max conditions manifests itself mainly as a large decrease in the longitudinal variation
of ozone after the storm, which means an increase of ozone in Europe. The observed effects in total ozone consist in redistribution,
not production or loss of ozone. 相似文献
5.
Elimination of Swimming Pool Water Disinfection By‐products with Advanced Oxidation Processes (AOPs)
Ozonation is a treatment step which was first applied in the 1960s in pool water treatment for disinfection as well as for oxidation of pool water contaminants. Contact time between ozone and pool water was identified to be of significance with an increased elimination efficiency regarding chloramines, trihalogenmethane formation potential and the permanganate index for longer reaction times. Oxidation via OH radicals might be the dominating pathway. In this study ozonation was compared with the ozone based advanced oxidation processes ozone/UV and ozone/hydrogen peroxide regarding the elimination efficiency of both disinfection by‐products (DBPs) and DBP precursors. It was observed that AOPs in comparison to ozonation showed an increased elimination efficiency regarding total organic carbon (TOC), the organically bound halogens adsorbable on activated carbon (AOX) and AOX formation potential. A contact time of 3 minutes between pool water and oxidant turned out to be practically sufficient. Just for the trihalomethane (THM) formation potential ozonation showed a slight advantage compared to the AOPs because ozonation is a highly selective oxidant and OH radical reactions are known to produce small reactive molecules which are easier transformed to THMs. Combination of membrane filtration and AOPs resulted in an elimination of 10 to 90 % of the DBPs and their precursors. The ozone/hydrogen peroxide process is suggested for pool water treatment because of the higher elimination rates compared to ozonation and of economic reasons compared to the ozone/UV process. 相似文献
6.
Accurate calculation of the solar radiation at the earth’s surface requires evaluation of the atmospheric ozone transmission. To use the existing methods one needs to know the atmospheric ozone amount. The serious lack of ozone data makes almost impossible the application of these methods in most of the world. In this paper a new method of estimating the overall ozone attenuation in the Northern Hemisphere is presented. Multiyear monthly latitudinal average ozone data are used. A daily ozone transmission function is proposed, and values of it are calculated for each latitudinal circle from 0° to 70°N at 10 longitude-degree intervals. By regression techniques parameterized expressions of the daily ozone transmission in the Northern Hemisphere are obtained as a function of the latitude. The model is applied to Athens, and the results are in excellent agreement with those obtained by extremely detailed calculations of the ozone transmission. The reliability of the model, under special regional ozone conditions, is investigated. Calculations for 67 locations in the Northern Hemisphere prove that the deviations do not exceed 1 percent. The influence of the year-by-year ozone variability is also examined, and the maximum deviation is found to be near 1.6 percent. The proposed model can be easily incoporated into solar radiation models in order to provide the ozone depletion at any place in the Northern Hemisphere where atmospheric ozone data are not available. 相似文献
7.
G. N. Kopylova E. M. Gorbunova S. V. Boldina D. V. Pavlov 《Izvestiya Physics of the Solid Earth》2009,45(10):905-913
Statically isolated conditions in the stratum-borehole hydrogeological system under consideration at periods of ≥ 3 h are
established on the basis of the investigation of barometric and tidal responses of the water level in a borehole located in
the territory of the Mikhnevo Geophysical Observatory, Institute of Geosphere Dynamics, Russian Academy of Sciences. The barometric
effectiveness, tidal sensitivity of the water level, elastic parameters, and porosity of water-bearing rocks are estimated.
A model of the inertial character of the water exchange in the stratum-borehole system is constructed depending on the period
of variations with allowance for the borehole design, as well as the water transmissibility and elastic capacity of the aquifer.
The results of modeling are in compliance with the dependence of the amplitude transfer function from variations in the atmospheric
pressure to variations in the water level. The results of processing the data of high-precision measurements made it possible
to refine the transmissibility of the aquifer obtained from the data of experimental filtration works. 相似文献
8.
A procedure for assessing errors, accompanying the assigning and implementing the standards for discharge of pollutants into
water bodies, is presented. It was found that, because of the poor reproduction of dose-effect relationship in laboratory
and natural environments, the standardization error may reach several tens of percent. A concept of standardization is proposed,
involving statistical control at the stages of assigning standards and wastewater transfer with testing hypotheses about the
adequacy of dose-effect relationships under laboratory and natural conditions. 相似文献
9.
Photosynthetically active radiation (PAR) is essential for plant photosynthesis and carbon cycle, and is also important for meteorological and environmental monitoring. To advance China’s disaster and environmental monitoring capabilities, the HJ-1A/B satellites have been placed in Earth orbit. One of their environmental monitoring objectives is the study of PAR. We simulated direct solar, scattered and environment radiation between 400 and 700 nm under different atmospheric parameters (solar zenith angle, atmospheric water vapor, atmospheric ozone, aerosol optical thickness, surface elevation and surface albedo), and then established a look-up table between these input parameters and PAR. Based on the look-up table, we used HJ-1A/B aerosol and surface albedo outputs to derive the corresponding PAR. Validation of inversed instantaneous and observed PAR values using HJ-1 Heihe experimental data had a root mean square error of 25.2 W m?2, with a relative error of 5.9%. The root mean square error for accumulated daily PAR and observed values was 0.49 MJ m?2, with a relative error of 3.5%. Our approach improved significantly the computational efficiency, compared with using directly radiation transfer equations. We also studied the sensitivity of various input parameters to photosynthetically active radiation, and found that solar zenith angle and atmospheric aerosols were sensitive PAR parameters. Surface albedo had some effect on PAR, but water vapor and ozone had minimal impact on PAR. 相似文献
10.
A method for the trace-level determination of bromate in raw and drinking water is reported. The procedure combines the quantitation of bromate by ion chromatography with a concentration step which in the main is composed of an unselective enrichment of all water constituents by means of a rotatory evaporator and a selective removal of the chloride ions. With this method, the reliable determination of bromate in raw and drinking waters is possible down to concentrations of at least 1 μg/L. The method is used for systematic examinations in several German waterworks which use ozone for the preparation of drinking water. The resulting data clearly prove that during the ozonation of bromide-containing waters, bromate is produced, whereby the concentration of bromate in the ozonated raw water can exceed 10 μg/L. Some correlations between the amount of bromate and the respective conditions of ozonation are pointed out. 相似文献
11.
Obtaining an accurate, value for total ozone under a cloudy sky, especially when the sun is not high, is a major remaining problem associated with total ozone measurements. The Toronto spectrophotometer has been designed with this in mind. It has been fitted with a polarizing prism, and measures light at four wavelengths simultaneous which makes it possible to obtain two independent double ratios. Clouds produce two effects on ozone measurements; the first is purely an optical effect which causes an apparent increase in ozone, the second is most likely a real increase in ozone associated with large cumulus-type clouds. By considering the three following points it is possible to distinguish between these two cloud effects and probably measure the true total ozone for solar zenith angles less than 80°: 1. The multiply scattered component of polarized light is used to reduce optical cloud variance. This makes all skies appear like thick coulds. 2. A double difference similar to the AD method is used but the two ratios of the double difference are weighted inversely with(=
1
-
2
for a pair). This further reduces the optical effects of clouds. 3. Real ozone increases due to large clouds are verified by comparing the increase of ozone obtained from one double difference to that of another. Differences between this multiply, polarized curve and the direct sun curve will be given, and a technique to obtain an accurate value of total ozone under all sky conditions, provided that the solar zenith angle is less than 80°, will be given. 相似文献
12.
A one-dimensional atmospheric photochemical model with an altitude grid of about 1.5 km was used to examine the structure of the global mean vertical ozone profile and its night-time-to-daytime variation in the upper atmosphere. Two distinct ozone layers are predicted, separated by a sharp drop in the ozone concentration near the mesopause. This naturally occurring mesopause ozone deep minimum is primarily produced by the rapid increase in the destruction of water vapour, and hence increase in HOx, at altitudes between 80 and 85 km, a region where water-vapour photodissociation by ultraviolet radiation of the solar Lyman-alpha line is significant, and where the supply of water vapour is maintained by methane oxidation even for very dry conditions at the tropospheric-stratospheric exchange region. The model indicates that the depth of the mesopause ozone minimum is limited by the efficiency with which inactive molecular hydrogen is produced, either by the conversion of atomic hydrogen to molecular hydrogen via one of the reaction channels of H with HO2, or by Lyman-alpha photodissociation of water vapour via the channel that leads to the production of molecular hydrogen. The ozone concentration rapidly recovers above 85 km due to the rapid increase in O produced by the photodissociation of O2 by absorption of ultraviolet solar radiation in the Schumann-Runge bands and continuum. Above 90 km, there is a decrease in ozone due to photolysis as the production of ozone through the three-body recombination of O2 and O becomes slower with decreasing pressure. The model also predicts two peaks in the night-time/daytime ozone ratio, one near 75 km and the other near 110 km, plus a strong peak in the night-time/daytime ratio of OH near 110 km. Recent observational evidence supports the predictions of the model. 相似文献
13.
A Na‐montmorillonite membrane wastewater renovation prototype system was developed to specifically treat an ionic azo dye. Efficiency of this prototype system was limited to membrane fouling. Fouling rates were not consistently uniform owing to steric effects and competition for exchange sites. The decrease in solute rejection with time can be attributed to the decrease in the relative permeability of the compacted Na‐montmorillonite membrane to the dye with time due to fouling. This decrease occurs probably as a two‐step nucleation–growth mechanism with the nucleation part dependent in part on solvent flux, number of nucleation sites on the membrane, and sorbed mass part that controls solute flux and organic polymerization. The effect of concentration polarization was significant since the flux was higher than the mass‐transfer coefficient. The low diffusion coefficient of the ionic azo dye resulted in low mass transfer coefficients. The most important macromolecular solution properties to be considered for pilot systems may include high concentration‐dependent viscosity, possible non‐Newtonian fluid behavior, and low and concentration‐dependent self‐diffusivity amongst other factors. For pilot systems, the greater the quantity of large macromolecules in the ambient water, the greater the necessity of reducing the permselectivity of the membrane to prevent significant polarization. 相似文献
14.
Processes of natural water ozonolysis are studied with the aim to determine the concentration of dissolved organic compounds
by intensity of chemoluminescence resulting from the interaction between ozone and organic molecules. Experimental results
are obtained with the use of an installation for recording ozone-chemoluminescence, which made it possible to study the potentialities
of the new method and the effect of factors that can have a negative effect on water quality. 相似文献
15.
Photosynthetically active radiation (PAR) is essential for plant photosynthesis and carbon cycle, and is also important for meteorological and environmental monitoring. To advance China’s disaster and environmental monitoring capabilities, the HJ-1A/B satellites have been placed in Earth orbit. One of their environmental monitoring objectives is the study of PAR. We simulated direct solar, scattered and environment radiation between 400 and 700 nm under different atmospheric parameters (solar zenith angle, atmospheric water vapor, atmospheric ozone, aerosol optical thickness, surface elevation and surface albedo), and then established a look-up table between these input parameters and PAR. Based on the look-up table, we used HJ-1A/B aerosol and surface albedo outputs to derive the corresponding PAR. Validation of inversed instantaneous and observed PAR values using HJ-1 Heihe experimental data had a root mean square error of 25.2 W m−2, with a relative error of 5.9%. The root mean square error for accumulated daily PAR and observed values was 0.49 MJ m−2, with a relative error of 3.5%. Our approach improved significantly the computational efficiency, compared with using directly radiation transfer equations. We also studied the sensitivity of various input parameters to photosynthetically active radiation, and found that solar zenith angle and atmospheric aerosols were sensitive PAR parameters. Surface albedo had some effect on PAR, but water vapor and ozone had minimal impact on PAR.
相似文献16.
P. Mlch 《Studia Geophysica et Geodaetica》1994,38(4):423-429
Summary This paper is a continuation of the recent studies of ozone response to major geomagnetic storms, now for the non-winter period.
No significant response was found under different solar cycle/QBO conditions due to a rather homogeneous distribution of ozone
during this period. Nevertheless, locations of the largest ozone variability are the same as the centers of meteorological
activity and closely related to the centers of quasi-persistent extremes in the geographical distribution of total ozone along
latitudinal circle 50 N. 相似文献
17.
Water repellency is a widespread property of Pinus pinaster and Eucalyptus globulus forest soils in NW Spain and is particularly severe during the summer dry conditions. The aim of this work was to compare actual water repellency at field‐moist samples with potential water repellency after drying at 25 and 105 °C in samples collected at different times of year under four forest soils. Also, we investigated whether drying at 25 or 105 °C led to repellency values comparable to the highest levels reached under field conditions in the summer with a view to developing an appropriate sampling protocol towards estimating the maximum possible water repellency of a given soil as a key to establishing its environmental effects. The actual and potential water repellency was determined by using the water drop penetration time (WDPT) and molarity of an ethanol drop (MED) tests. Clear seasonal patterns of water repellency were observed from the results for the four forest soils, peaking in the dry period and disappearing after prolonged wet periods. Water repellency lasts longer in sandy loam soils than in more finely textured soils, and also under eucalyptus than under pine forests. Drying soil samples at 25 or 105 °C increased water repellency, as measured with the WDPT method, in the four soils, but especially in the non‐repellent samples collected during the wet period. The increase was more marked in the sandy loam soils than in the more finely textured soils, and also after drying at 105 °C than at 25 °C. MED measurements exposed a common trait in the four soils; thus, the water repellency values obtained under field conditions in summer invariably exceeded those obtained after drying at 25 or 105 °C. In addition, the repellency values for dried samples collected in the wet period were never comparable to the maximum levels observed under field conditions in the summer. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
18.
An observation by UHF ST radar of a subsidence pattern on the right side of the exit region of a jet streak is reported. The onset of the subsidence pattern occurred at 23:30 UTC on the 29 November 1991, when a downward motion was initiated above 14 km. The injections of stratospheric air in this region seem to have an intermittent nature; they occur during at least three intervals during the lifetime of the subsidence pattern. Comparison of these results with an ECMWF analysis suggests that it is an unfolding case. However, observation of turbulent intensities w’ greater than 60 cm s−1 at the tropopause level also suggests the existence of a turbulent flux between the stratosphere and the troposphere. From the turbulence characteristics measured by the radar and the potential temperature profile obtained by radiosonde data, the eddy diffusivity at the tropopause level has been calculated. An eddy diffusion coefficient ranging between 5 and 7 m2 s−1 is found. From these values, and with the assumption of a climatological gradient of the volume mixing ratio of ozone in the lower stratosphere, it is possible to deduce a rough estimate of the amount of ozone injected from the stratosphere into the troposphere during this event. A rate of transfer of 1.5×1020 molecules of ozone per day and per square meter is found. 相似文献
19.
Francisco J. Moral Francisco J. Rebollo Francisco Méndez 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(3):455-465
Ground-level tropospheric ozone is one of the air pollutants of most concern. Ozone levels become particularly high in regions close to high ozone precursor emissions and during summer, when high insolation and high temperatures are common. Ozone levels continue to exceed both target values and the long-term objectives established in EU legislation to protect human health and prevent damage to ecosystems, agricultural crops and materials. Researchers or decision-makers frequently need information about atmospheric pollution patterns in urbanized areas. The preparation of this type of information is a complex task, due to the influence of several factors and their variability over time. In this work, some results of urban ozone distribution patterns in the city of Badajoz, which is the largest (140,000 inhabitants) and most industrialized city in Extremadura region (southwest Spain) are shown. Twelve sampling campaigns, one per month, were carried out to measure ambient air ozone concentrations, during periods that were selected according to favourable conditions to ozone production, using an automatic portable analyzer. Later, to evaluate the overall ozone level at each sampling location during the time interval considered, the measured ozone data were analysed using a new methodology based on the formulation of the Rasch model. As a result, a classification of all locations according to the ozone level, which was the value of the Rasch measure, was obtained. Moreover, information about unexpected behaviours of ozone patterns was generated. Finally, overall ozone level at locations where no measurements were available was estimated which can be used to generate hazard assessment maps. 相似文献
20.
浅型富营养湖泊的生态恢复——五里湖水生植被重建实验 总被引：30，自引：4，他引：26
依据浅型湖泊生态系统的多稳定态理论,在富营养湖泊治理过程中,当外来污染得到有效控制时,通过人工重建水生植被可以加速湖泊的生态恢复。在五里湖中,挺水植物和浮叶植物都能很好地生长,水底光照不足是沉水植物难以生长的主要原因。在自然条件下建成了永久性挺水植物群落和浮叶植物群落,在人工控制的围隔环境中改善了水底光照条件,建成了沉水植物群落。但这些沉水植物仍不能渡过夏季,主要原因是湖水过深和水温较高,降低水位和建造人工浅滩可为五里湖沉水植被恢复创造有利条件。本研究可为富营养水体的水质控制和植被恢复提供多种实用技术,但在水生植被的结构与环境功能等方面仍需开展深入的定量研究。 相似文献