The Accumulation of Fluorine by Plants

The accumulation and distribution of fluorine (F) in -plant leaves have been studied to better understand the response of plants to concentrations of atmospheric fluoride (F) that are similar to those found in urban or industrial areas. The results indicate that F from the air can be adsorbed to the surface of leaves as well as accumulated internally and that F in leaves can be translocated outward to the surface as well as upward to the tips. F injury and accumulation can be induced in any desired location on a gladiolus blade by restricting gas exchange of the blade, indicating that all parts of a blade are sensitive to F-induced injury. It is, therefore, suggested that the wide differences often found between plant species and varieties with respect to both susceptibility to injury and degree of F accumulation may be explained by differences in the means of accumulation, trans-location, and distribution of F. F remains in a soluble form in plant leaves and maintains the chemical properties of free, inorganic F. The solubility and mobility of F and the ease of removal from plant tissues indicate that irreversible binding to cellular components does not occur.     

The role of a steel plant in north-west Italy to the local air concentrations of PCDD/Fs

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are ubiquitous contaminants, mainly released into the environment during combustion processes (point sources), but also from other sources (traffic, uncontrolled combustion).This study aims at investigating the contribution of a steel plant in NW Italy (700 000 tons of steel year⁻¹) to the air concentrations of PCDDs/PCDFs at local level, through the analysis of measured, modelled and literature data. The study was carried out in an area of 600 km², using air quality data measured by the institutional monitoring network, data obtained from AERMOD simulations and literature data.The measured air concentrations were consistent with literature values for similar areas, and both the homologue profiles and PCA analyses showed a clear distinction between the monitoring stations and the source profiles.All the previous results were confirmed by the air dispersion model (AERMOD), that predicted PCDD/F air concentrations due to the steel plant from four to two orders of magnitude lower than those measured in the monitoring stations, highlighting the presence of other sources.This study outlines the limited influence of the source in the local PCDD/F air concentrations and at the same time the usefulness of a joint analysis of measured, literature and calculated data to correctly evaluate the role of a source to the local pollution. The study also highlights the usefulness of AERMOD as a complementary tool to define the correct placement of monitoring stations and to locate those areas expected to have the highest air concentrations deriving from a source.     

南京市区植物叶片氮、硫、铅含量与大气污染评价

通过对南京市区的各功能区植物叶片中的氮、硫、铅元素含量的分析，研究了植物大气环境污染指数，探讨了植物叶片的氮、硫、铅元素含量的季节变化，以及与城市大气环境污染之间的关系。结果表明，植物叶片中，硫、铅元素的含量随季节变化不断增加，而氮元素含量相应减少；各功能区的硫、铅元素含量明显高于清洁对照区；用植物污染指数可以综合评价大气环境的质量状况。     

Public Health Service National Fallout Surveillance Program

A semi-automated method for determination of fluorine in biological materials has been developed incorporating the Technicon AutoAnalyzer. One-half gram of dried, ground plant material is ashed, alkali-fused, diluted with water, and the suspension is pumped, along with H₂SO₄, at controlled rates, into the hot revolving glass helix of a digestor unit. As the acid-digest mixture passes through the heated coil, volatile fluoride and water vapor are evolved. The volatile fluoride and water vapor are pulled from the helix under reduced pressure through a tube which projects into the helix. The tube, in turn, is connected to a water-jacketed condenser and then to an impinger where the sample is continuously mixed. An aliquot of the impinger liquid is being constantly withdrawn. This sample is then air-segmented and mixed with a reagent containing alizarin complexone, pH 4 acetate buffer, lanthanum nitrate, acetone, and water. The sample-reagent combination passes through 4 full-length mixing coils where color development takes place. Upon reacting with fluoride, the wine-red alizarin complexone-La(III) reagent forms a lilac blue fluoride complex. The solution is pumped from the mixing coils through the tubular flow cell of the colorimeter. The absorbence of the solution is measured at 624 mμ, and the signal is transmitted to a recorder where the results are plotted on absorbency paper. The absorbence at the apex of the peak is proportional to the amount of fluoride in the sample between the range of 2.5-80 μg °F. Samples are analyzed at a rate of 12 per hour. Results compare favorably with those obtained by Willard-Winter distillation. Recent studies indicate that the F content of plant tissues can be estimated without prior ashing and fusion     

Limitations of the Lead Acetate Impregnated Paper Tape Method for Hydrogen Sulfide

Field experience with the lead acetate impregnated paper tape sampler has indicated that large errors may arise in this method due to fading of the color of the precipitated lead sulfide spots. This fading is due to the action of light, sulfur dioxide, ozone, on other substances capable of oxidizing lead sulfide. The moisture content or relative humidity of the air sample must be maintained at an appropriate level to ensure reaction with the impregnated paper tape. The effects of the factors have been investigated in laboratory experiments with known concentrations of H₂S. A number of antioxidants were studied in relation to the stability of the resultant spots to light and oxidation Orthophenyl phenol was found to be the most effective antioxidant for this purpose. A number of necessary precautions to be employed in the use of the lead acetate method are recommended and the limitations are discussed.     

Evaluation of Probes Used for Source Sampling of Hydrogen Fluoride

The body of information presented in this paper is directed to those individuals concerned with methods for the sampling and measurement of fluorides contained in stack gases produced during the manufacture of phosphate fertilizer or aluminum. An air stream containing gaseous hydrogen fluoride (HF), at concentrations of from 87 to 1700 µg F m^-3, was generated and passed through 193 to 198 cm lengths of Pyrex glass, type 316 stainless steel, TFE Teflon, and methyl methacrylate-coated aluminum probes at flow rates of 28 I min^-1. HF passing through the probes was collected in deionized water contained in a Greenburg-Smith impinger. The Teflon probe exhibited no loss of HF and no trend toward increased passage of HF with time. Significant amounts of fluoride were lost in 18 out of 20 tests with the methacrylate probe and in 4 out of 20 tests with the Pyrex and stainless steel probes. Trends toward increased passage of HF with time occurred with the latter three probe materials. The selective ion electrode and semiautomated methods gave equivalent results when samples were made alkaline to avoid sorption of fluoride by Tygon tubing used in the semiautomated method. These results demonstrated that a Teflon probe gave the most representative sample of gaseous HF. However, additional tests are needed before a final recommendation is made for a probe to sample fluorides in stack gases.     

Significance of the long-term biomonitoring studies for understanding the impact of pollutants on the environment based on a synthesis of 25-year biomonitoring in the Holy Cross Mountains,Poland

This review presents compiled results of complex biomonitoring studies that have been conducted in the Holy Cross Mountains, south-central part of Poland, since the 1990s. The significance of these studies results from several aspects: (i) a number and a variety of plant organisms used, e.g., mosses, lichens, coniferous and deciduous trees, and their tissues (wood, bark, needles, leaves, the aboveground parts of several vascular plants); (ii) applications of a broad scope of instrumental methods aiming at determining major and trace elements (including rare earth elements), organic compounds (PAHs, PCBs, phenols), and stable sulfur isotopes (δ³⁴S); and (iii) different methodological and environmental issues addressed. The comparison and interpretation of results derived from seventeen sampling campaigns carried out between 1994 and 2017 are a valuable source of information on the following: (i) bioaccumulative properties of organisms used in air quality monitoring, (ii) identification and variations of local and regional pollution sources and geochemical landscape patterns and processes over years, and (iii) establishing environmental factors that variously affected chemical composition of plants growing under physiological stress, including roadside vegetation and plants from acid mine drainage areas.

     

Relating error bounds for maximum concentration estimates to diffusion meteorology uncertainty

The intent of this paper is to relate the magnitude of the error bounds of data, used as inputs to a Gaussian dispersion model, to the magnitude of the error bounds of the model output, which include the estimates of the maximum concentration and the distance to that maximum. The research specifically addresses the uncertainty in estimating the maximum concentrations from elevated buoyant sources during unstable atmospheric conditions, as these are most often of practical concern in regulatory decision making. A direct and quantitative link between the nature and magnitude of the input uncertainty and modeling results has not been previously investigated extensively. The ability to develop specific error bounds, tailored to the modeling situation, allows more informed application of the model estimates to the air quality issues.In this study, a numerical uncertainty analysis is performed using the Monte-Carlo technique to propagate the uncertainties associated with the model input. Uncertainties were assumed to exist in four model input parameters: (1) wind speed, (2) standard deviation of lateral wind direction fluctuations, (3) standard deviation of vertical wind direction fluctuations, and (4) plume rise. For each simulation, results were summarized characterizing the uncertainty in four features of the ground-level concentration pattern predicted by the model: (1) the magnitude of the maximum concentration, (2) the distance to the maximum concentration, and (3) and (4) the areas enclosed within the isopleths of 50% and 25% of the error-free estimate of maximum concentration.The authors conclude that the error bounds for the estimated maximum concentration and the distance to the maximum can be double that of the error bounds for individual model input parameters. The model output error bounds for the areas enclosed within isopleth values can be triple the error bounds of the input. It was not our intent to cover all possible combinations for the error in the input parameters. Ours was a much more limited goal of providing a lower bound estimate of model uncertainty in which we assume the input is reasonably well characterized and there is no bias in the input. These results allow estimation of minimum bounds on errors in model output when considering reasonable input error bounds.     

Air Quality Model Evaluation and Uncertainty

The many advances made in air quality model evaluation procedures during the past ten years are discussed and some components of model uncertainty presented. Simplified statistical procedures for operational model evaluation are suggested. The fundamental model performance measures are the mean bias, the mean square error, and the correlation. The bootstrap resampling technique is used to estimate confidence limits on the performance measures, In order to determine if a model agrees satisfactorily with data or if one model is significantly different from another model. Applications to two tracer experiments are described.

It is emphasized that review and evaluation of the scientific components of models are often of greater Importance than the strictly statistical evaluation. A necessary condition for acceptance Of a model should be that it is scientifically correct. It Is shown that even in research-grade tracer experiments, data Input errors can cause errors In hourly-average model predictions of point concentrations almost as large as the predictions themselves. The turbulent or stochastic component of model uncertainty has a similar magnitude. These components of the uncertainty decrease as averaging time increases.     

PCDD/Fs and PCBs in ambient air in a highly industrialized city in Northern Italy

Ambient air samples were collected in five locations around a polychlorobiphenyl (PCB) production plant in a highly industrialized city in the north of Italy, for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and PCBs.PCDD/F atmospheric concentrations were lower than those generally detected in urban areas, while PCB concentrations were higher than in urban and industrialized areas in other countries, especially in the locations closest to the plant. To identify source emissions responsible for air pollution we used principal component analysis (PCA) to compare the “fingerprint” of the air in Brescia with some source-related experimental and published data. This analysis showed that the PCDD/F fingerprints were more similar to steel plant emission data, while none of the PCB air patterns were comparable to emission profiles, indicating that different sources are responsible for the concentration of these two pollutants. The highest PCB concentrations detected in the areas closest to the chemical plant are indicative of its impact on the surrounding environment.     

Performance of the annular denuder system with different arrangements for HNO3 and HNO2 measurements in Taiwan

Experiments on different annular denuder system (ADS) arrangements for sampling nitrous acid (HNO2) and nitric acid (HNO3) gases were conducted in this study to evaluate their sampling artifacts. The evaluation basis is the one that employed one sodium chloride denuder for sampling HNO3 gas and two sodium carbonate (Na2CO3) denuders for sampling HNO2 gas, which is a commonly employed ADS arrangement in many field applications in the United States. A field study was conducted in Hsinchu, Taiwan, and the results indicated that this ADS arrangement may yield over 80% relative errors for HNO3 gas. It also showed that the relative errors for HNO2 gas can be less than 10% as sampled with only one Na2CO3 denuder. This is attributed to the fact that the ambient HNO3 concentration measured in this study was relatively low while the HNO2 concentration was high, as compared to typical concentrations of these two gases measured in the United States. The sampling error of HNO3 gas may be due to high concentrations of N-containing interfering species present in Taiwan's atmosphere. Because the relative sampling errors of HNO3 and HNO2 gases depend mainly on their concentrations in the atmosphere as well as concentrations caused by interfering species, the risk for high error while measuring low HNO2 concentrations by only one Na2CO3 denuder is also possible. As a result, it is suggested that pretests are necessary to evaluate possible sources and degrees of sampling errors before field sampling of HNO2 and HNO3 gases. The sampling errors of these two gases can, therefore, be minimized with a better arrangement of the ADS.     

Assessing the impact of differential measurement error on estimates of fine particle mortality

In air pollution epidemiology, error in measurements of correlated pollutants has been advanced as a reason to distrust regressions that find statistically significant weak associations. Much of the related debate in the literature and elsewhere has been qualitative. To promote quantitative evaluation of such errors, this paper develops an air pollution time-series model based on correlations among unit-normal variables. Assuming there are no other sources of bias present, the model shows the expected amount of relative bias in the regression coefficients of a bivariate regression of coarse and fine particulate matter measurements on daily mortality. The model only requires information on instrumental error and spatial variability, along with the observed regression coefficients and information on the true fine-course correlation. Analytical results show that if one pollutant is truly more harmful than the other, then it must be measured more precisely than the other in order not to bias the ratio of the fine and course regression coefficients. Utilizing published data, a case study of the Harvard Six-Cities study illustrates use of the model and emphasizes the need for data on spatial variability across the study area. Current epidemiology time-series regressions can use this model to address the general concern of correlated pollutants with differing measurement errors.     

Splitting error estimation for micro-physical–multiphase chemical systems in meso-scale air quality models

Operator splitting applied to cloud micro-physical and multiphase chemical process causes the so-called operator splitting errors in addition to other numerical errors when used in numerical models. Operator splitting is mainly used due to limited computer resources or for historical reasons. Unfortunately, it is impossible so far to theoretically estimate either the order of magnitude or the tendency of the splitting errors in complex non-linear systems such as mutually interacting cloud chemical and micro-physical processes.The present study systematically investigates the splitting error mentioned above, by numerical means to define valid ranges of the applicability of the method of operator splitting to those systems. Results of the current study show that de-coupling intervals larger than 100 s cause an underestimation of the total liquid water content as well as the particle radius of the order of 10% for simulation periods of 1000 s. The maximum overprediction of the total content of dissolved material in the particles is of the order of about 20% for de-coupling intervals of 10–15 min. The error in the sulphate production contributes about 50% to the discrepancy in total aerosol content. Since the de-coupling intervals between dynamical, micro-physical, and chemical processes in most recent air quality models are considerably longer than 15 min, the consequences of the application of operator splitting requires further investigation with respect to predicted aerosol formation, cloud water content, deposition rates, photo-chemistry, cloud optical properties, etc.     

Butyltins in muscle and liver of fish collected from certain Asian and Oceanian countries

Concentrations of butyltin residues were determined in muscle tissue of fish collected from local markets and sea food shops in India, Bangladesh, Thailand, Indonesia, Vietnam, Taiwan, Australia, Papua New Guinea and the Solomon Islands. Contamination levels were determined in the Asia-Pacific region and human exposure was estimated. Similarly, corresponding liver samples of fish muscle collected in Australia, Papua New Guinea and the Solomon Islands were analyzed to obtain information on partitioning of butyltin compounds between muscle and liver tissues. Butyltin compounds were detected in most of the samples which suggested widespread contamination in Asia and Oceania. The concentrations of butyltin compounds were, on average, an order of magnitude higher in liver than in muscle. Residue concentration of Sigmabutyltin in liver was found to be correlated significantly (p < 0.02) with those in muscle. Intensive ship-scrapping activities, sewage disposal and antifouling paints are considered the major sources of butyltins in this region. Increased proportions of MBT over DBT and TBT in samples from most locations indicated degradation of TBT to MBT in fish tissues during storage at 4 degrees C in the dark over 1-2 years. The possibility that fish have been subject to increased exposure to MBT and that TBT degrades to MBT quite rapidly in tropical environments are also considered. Butyltin concentrations in fish from Asia and Oceania were lower than those reported for Japan, Canada and the USA. Although the number of samples analyzed from each country was small, it is tentatively suggested that intake of butyltins by humans via consumption of fish in these countries was < 25% of the tolerable daily intake of 250 ng kg bw(-1) day(-1). To our knowledge, this is the first study reporting on butyltin pollution in developing Asian countries.     

Measurement of Opacity and Particulate Emissions with an On-Stack Transmissometer

An on-stack transmissometer system which is designed to provide a precision measurement of the opacity of visible emissions is described. The sources of error in opacity measurements with regard to recent EPA emission monitoring requirements and planned specifications are discussed. Sources of error are voltage changes, temperature changes, light source and detector aging and effects of ambient light. Other major operational errors are caused by alignment drift and soiling drift. The methods employed to minimize these errors achieve an accuracy of ±3% of span and a maintenance free operational period of 3 months. The relationships between optical density, opacity and transmittance are described. The instrument measurement can be correlated with dust loading provided the particle size distribution is constant. Examples are given of correlations obtained between optical density and particulate concentration in the gas on various types of emission sources and the observed error margins are summarized.     

Effects of scrubber by-product-stabilized dairy lagoon sludge on growth and physiological responses of sunflower (Helianthus annuus L.)

Brick manufacturing industries are challenged to comply with clean air mandates. Dry air scrubbers have been used to remove acid gases from the exhaust air from brick manufacturing plants. The use of dry air scrubbers results in the production of large quantities of an alkaline powder by-product. A greenhouse experiment was conducted to evaluate the potential of using dairy lagoon sludge stabilized with the scrubber by-product as a soil amendment. Lagoon sludge was stabilized with scrubber by-product at an application rate of 20 gl(-1). The sludge-scrubber by-product mixture was applied to a sandy loam soil to provide amendments ranging between 28 and 168 kg of plant available nitrogen (PAN)/ha for the growth of Helianthus annuus (sunflower). Use of the sludge-scrubber by-product mixture as a nitrogen fertilizer did not adversely affect sunflower seedling emergence; however, significantly higher (p<0.05) plant volume indices, leaf area, dry shoot and root masses, and seed yields were obtained for mature plants grown in sludge-treated soil relative to the control or fertilizer treatment. The sludge amendment did not severely impact gas exchange or chlorophyll a fluorescence of the plants and nutrient content of the sunflower tissues was generally within a sufficient range. The increased growth and yield of sunflower plants indicated the potential of the sludge-scrubber by-product mixture as a soil amendment in agricultural crop production.     

Fiber Glass Fabric Filters for High Temperature Dust and Fume Control

Foliar markings on vegetation have proven a highly sensitive criterion for the presence of many air pollutants; proper evaluation of such effects can serve as a valuable and inexpensive tool for delineating an air pollution condition. Injury symptoms from fluoridt, sulfur dioxide, photochemical oxidants and other pollutants have been described and can be recognized by experienced observers. Field studies provide a valuable technique for appraising an air pollution problem when diagnosis is not confused by other factors. Careful inspection can avert difficulties arising in diagnosis where similar symptoms are produced by agents other than air pollutants. Several factors must be considered in appraising injury. These include a knowledge of the relative sensitivity of plant species to various pollutants, the syndrome of injury on a number of plants and species, and distribution and geographic relation of affected plants to the suspected source. Background information on cultural, environmental, disease and insect conditions which might be responsible for, or modify, foliar markings or chronic effects in question must also be understood. For some pollutants a chemical analysis of foliage and air may prove helpful. When these factors are studied, the presence, distribution and magnitude of an air pollution situation can be evaluated, thus providing a sensitive criterion of air quality.     

Exposure of oats, Avena sativa L., to filtered and unfiltered air in open-top chambers: effects on grain yield and quality

Field grown oats, Avena sativa L. cv Vital, were exposed to filtered and unfiltered air from anthesis until harvest in open-top chambers at a site in south-west Sweden. Ambient plots were used to study the influence of the chamber itself. With the exception of the number of grains per panicle, which was significantly higher in the charcoal-filtered treatment, no significant filtration effects were obtained for any of the plant growth parameters studied), i.e. grain yield, number of panicles per square metre, 1000-grain weight, straw yield and harvest index.) The chamber had a significant negative effect on grain yield, 1000-grain weight and straw yield. None of the yield quality parameters that were measured, such as crude protein content, crude fibre content, fat content, volume weight of the grain and water content of the grain at harvest, were significantly influenced by either air filtration, or the presence of the chamber. The chlorophyll content of the flag leaves was higher in the charcoal-filtered treatment than in the non-filtered and ambient air treatments towards the end of the experiment, indicating that filtering of the air delayed senescence. The decline of the shoot area after the onset of plant senescence proceeded faster in both chamber treatments. The faster development in the chamber was explained by the faster accumulation of thermal time in the chamber.     

Sources of dioxins in the United Kingdom: the steel industry and other sources

Several countries have compiled national inventories of dioxin (polychlorinated dibenzo-p-dioxin [PCDD] and polychlorinated dibenzofuran [PCDF]) releases that detail annual mass emission estimates for regulated sources. High temperature processes, such as commercial waste incineration and iron ore sintering used in the production of iron and steel, have been identified as point sources of dioxins. Other important releases of dioxins are from various diffuse sources such as bonfire burning and domestic heating. The PCDD/F inventory for emissions to air in the UK has decreased significantly from 1995 to 1998 because of reduced emissions from waste incinerators which now generally operate at waste gas stack emissions of 1 ng I-TEQ/Nm3 or below. The iron ore sintering process is the only noteworthy source of PCDD/Fs at integrated iron and steelworks operated by Corus (formerly British Steel plc) in the UK. The mean waste gas stack PCDD/F concentration for this process is 1,2 ng I-TEQ/Nm3 based on 94 measurements and it has been estimated that this results in an annual mass release of approximately 38 g I-TEQ per annum. Diffuse sources now form a major contribution to the UK inventory as PCDD/Fs from regulated sources have decreased, for example, the annual celebration of Bonfire Night on 5th November in the UK causes an estimated release of 30 g I-TEQ, similar to that emitted by five sinter plants in the UK.     

Remediation of MTBE from drinking water: air stripping followed by off-gas adsorption

The widespread use of methyl tertiary butyl ether (MTBE) as an oxygenate in gasoline has resulted in the contamination of a large number of ground and surface water sources. Even though air stripping has been proven to be an effective treatment technology for MTBE removal, off-gas treatment often is required in conjunction with it. This study evaluated the combined treatment technologies of air stripping followed by off-gas adsorption on a pilot scale for the treatment of MTBE-contaminated water. The effect of air/water ratios on the treatment efficiency was studied, and the mass transfer coefficient was determined. Air/water ratios of 105:1, 151:1, 177:1, 190:1, 202:1, and 206:1 were used, and a treatment efficiency of >99% was achieved for all the runs conducted. The depth of packing required to achieve maximum treatment efficiency decreased with increasing air/water ratio. Relative humidity (RH) impacts on the MTBE adsorption capacity of a granular activated carbon (GAC) and carbonaceous resin were determined from pilot plant studies. Breakthrough profiles obtained from the pilot plant studies conducted at 20, 30, and 50% RH indicated that GAC has a higher adsorptive capacity than resin. The adsorptive capacity of GAC decreased with increasing RH, whereas RH did not impact the resin adsorptive capacity.