Hydrogen Fluoride Concentration Research Articles

Relationship of concentration of gaseous hydrogen fluoride to incidence and severity of foliar lesions in black spruce and white spruce

Quantitative estimates of the variation in response to air pollutants in natural populations of trees must be considered in predicting the magnitude of an effect or the risk of an effect's occurrence. This subject was investigated in 2-year-old black spruce (Piceamariana (Mill.) B.S.P.) exposed for 78 continuous hours to gaseous hydrogen fluoride at concentrations of 2.3, 4.2, or 8.1 μg% F•m−3 and with 3-year-old white spruce (Piceaglauca (Moench) Voss) exposed for 50 continuous hours to hydrogen fluoride at 2.6, 5.2, or 11.1 μg F•m−3 in open-top, field exposure chambers. Tolerances to hydrogen fluoride induced foliar injury followed a lognormal distribution for black spruce and white spruce with, respectively, estimated median tolerances of 3.45 and 13.24 μg F•m−3 and standard deviations corresponding to 1.70- and 2.14-fold changes in concentration of hydrogen fluoride. The curves for the occurrence of moderate and severe degrees of injury in black spruce paralleled that for the occurrence of any hydrogen fluoride induced injury but were displaced towards greater exposures (1.29-fold for moderate and 1.77-fold for severe injury). The distribution of foliar injury on shoots indicated that a portion of the variation in tolerance might be attributed to phenologic differences among the trees. A knowledge of the sources of variation and their magnitudes is necessary to recognize both incidence and severity of pollutant-induced injury in dose-response relationships.

Some chemical characteristics of the brines in Bannock and Tyro Basins: salinity, sulphur compounds, Ca 2+, F −, pH, At, PO 3−4, SiO 2, NH 3

Results of the chemical investigation on the Bannock and Tyro Basins are reported. Both basins were found to be hypersaline (∼ 10 times higher than salinity of normal seawater) and anoxic. In all investigated basins a region of transition, a few meters thick, was identified at depths > 3327 dbar. It is characterized by a sharp gradient of salinity, and all concentrations of analysed species increase strongly except for dissolved oxygen and nitrate, which immediately drop to zero. This region appears as a sharp boundary that prevents mixing. As a result, in the presence of organic matter, an anoxic condition developed with the complete depletion of dissolved oxygen. At the same time, hydrogen sulphide and ammonium accumulated within the brine. Between the Bannock and the Tyro brines differences occur in the measured concentrations of H 2S, SO 2− 4, Ca 2+ and NH 3. There are some differences also within the Bannock area sub-basins. The Libeccio sub-basin, in the Bannock area, contains a double-layered brine: the upper layer is ∼ 140 dbar thick and the lower layer is ∼300 dbar thick. A second interface between upper and lower brines develops at a depth of ∼3500 dbar. Nearly all of the measured concentrations vs. depth show the double layer, with the exception of ammonium, the concentration of which remains nearly constant throughout the anoxic column. Profiles of the other species analyzed show remarkable differences on passing from the upper to the lower brine. Hydrogen sulphide, sulphate and fluoride concentrations appear constant and then increase at the second interface. The calcium concentration is also constant in the upper brine, but decreases at the second interface. Total alkalinity and phosphate concentrations show a maximum peak just below the first interface. However, after passing through the second interface all the chemical parameters exhibit an almost constant behaviour down to the bottom. Hypersaline conditions are attributed to the dissolution of Messinian evaporite, and anoxia is suggested to originate from the oxidation of organic matter present in sediments and from the absence of bottom water circulation in such a deep and enclosed environment. The chemical conditions can be summarized as follows: in the Libeccio Basin the values for the species analysed have the ranges: 39–321 psu for ‘salinity’, 8.2−6.5 for pH, 2.7–4.0 mM for total alkalinity, 0.2-0 mM for dissolved oxygen, 0–1669 μM for hydrogen sulphide, 0–198 μM for thiol, 31–99 mM for sulphate, 11–21 mM for calcium, 7–100 μM for fluoride, 0.2–3080 μM for ammonium, 5.8-0 μM for nitrite, 0.2–12 μM for phosphate and 8–130 μM for silicate.

Analysis of vapor barrier experiments to evaluate their effectiveness as a means to mitigate HF cloud concentrations

Accidental release of Hydrogen Fluoride (HF) can result in initially dense, highly reactive and corrosive gas clouds. These clouds will typically contain a mixture of gases, aerosols and droplets which can be transported significant distances before lower hazard levels of HF concentration are reached. Previous related field and laboratory experiments have been analyzed to estimate the effectiveness of barrier devices. The experiments were examined to determine their relevance to Hydrogen Fluoride spill scenarios. Wind tunnel and field data were compared where possible to validate the laboratory experiments. Barrier influence on peak concentrations, cloud arrival time, peak concentration arrival time, and cloud departure time were determined. These data were used to develop entrainment models to incorporate into integral and depth averaged numerical models. The models were then run to examine barrier performance for a typical Hydrogen Fluoride spill for a wide range of vapor barrier heights, spill sizes, meteorological conditions and release configurations. Finally the results of the data analysis and numerical sensitivity study were interpreted and expressed in a form useful to evaluate the efficiency of vapor barrier mitigation devices.

Fluoride-induced enhancement and inhibition of shoot growth in four taxa of Pinus.

Pinus elliottii Englem. Var. elliottii (PEE) and three varieties of Pinus caribaca morelet [var. caribaca barr. Et Golf. (PCC), var bahamensisi Barr. et Golf. (PCB) and var. hondurensis (PCH)] were grown at gaseous hydrogen fluoride concentrations of 0.0, 1.2, 1.8 and 4.3 μ F m-3 during a period of 200 d. Extension growth of the mainstem and lateral branches was not significantly affected by fluoride in any taxon. Overbark diameter increment at the stem base was signicantly greater at 1.2 μg F m-3 than at 0, 1.8 or 4.3 μ F m-3 in all taxa, and also near the stem apex in PEE. Only in PEE was the stem base diameter increment lower at 4.3 μ F m-3 than in control plants. Lateral branch diameter increments were not signicantly affected by ambient fluoride concentration. Stem base diameter increments in all taxa linearly related to the rates of photosynthesis I needles 4-8 weeks old.

Fluorosilicate equilibria in acid solution

The reaction between silicic acid and the fluoride ion in aqueous solution has been investigated at 25°C in a 3 m (Li)ClO4 medium, by potentiometric methods employing a fluoride ion-selective electrode to observe the free hydrogen fluoride concentration. The acidity varied between 0.3 and 3 m, while the concentration of silicic acid was maintained below 2.5 x 10−3 m which is thought to be the saturation level of amorphous silica. The experimental data have been explained in terms of Si(OH)3F, SiF4, SiF62−, HSiF6− and a minor species to which the composition Si(OH)2F+ has been tentatively assigned.

Concentrations of hydrogen chloride and hydrogen fluoride measured during the MAP/GLOBUS campaign of September 1983

Within the context of the MAP/GLOBUS campaign of September 1983, several trace species have been observed by absorption spectroscopy at the two ground stations of the Jungfraujoch, Switzerland (3580 m altitude) and the Observatoire de Haute-Provence, France (1905 m altitude). The results obtained for HCl and for HF, expressed in terms of mean integrated columns above these sites are: Jungfraujoch: (2.1 ± 0.2) E15 mol cm −2 HCl (4.8 ± 0.2) E14 mol cm −2 HF Haute-Provence: (2.6 ± 0.2) E15 mol cm −2 HCl. Taking into account the difference in the altitude of the two stations, the reported HC1 results are in agreement to within their respective uncertainties. The integrated column density of HCl and HF above 11 km altitude, deduced from airplane observations on 9 September 1983, are: (1.65 ± 0.25) E15 mol cm −2 HCl above 11 km (3.7 ± 1.7) E14 mol cm −2 HF above 10 km supporting satisfactorily the ground measurements.

Fluoride-induced suture red spot in ‘Elberta’ peach

Suture red spot (SRS) is a serious physiological disorder of the peach fruit. Tissues at or near the suture ripen prematurely and the affected becomes soft or overripe before the remainder of the fruit ripens, rendering it unmarketable. SRS may be induced by several agents, including fluorine (F)-containing compounds. Different kinds of exposures of ‘Elberta’ peach trees to hydrogen fluoride (HF) in the field revealed that the concentrations of HF for the induction of this disorder were extremely low: 0.3 μgF m −3 in continuous exposures of 80 days; 1.0 μgF m −3 in intermittent exposures for three 6-hr periods each week for 9 weeks. Fruits were more susceptible to HF-induced SRS at the later stages of fruit development than at the pit-hardening stage. Exposure to HF induced a localized deficiency of calcium (Ca) in suture tissues. It is postulated that this could have resulted in loss of membrane integrity leading to premature ripening and the development of SRS.

Investigation of ion-selective electrodes based on quanternary phosphonium salts: Part 3. An Ion-Selective Electrode for Hexafluorophosphate

A hexafluorophosphate-selective electrode based on the tetradecylphosphonium hexafluorophosphate(V) ion-pair complex in a PVC membrane is described. The active material is a white powder; its solution in dibutyl phthalate was used for the electrode membranes. The composition of the tetradecylphosphonium hexafluorophosphate was identified as its infrared and 31P-n.m.r. spectra. The calibration curves for the elelctrode were investigated and interpreted with respect to the hydrogen fluoride concentration of the sample solution. It is shown that the hydrolysis of hexafluorophosphate depends on the hydrofluoric acid content of the solution. The lifetime of the electrodes is about one month and the limits of detection vary from aobut 10 −7 mol 1 −1 to 10 −6 mol 1 −1 with 0–1 mol 1 −1 hydrofluoric acid present.

Growth and yield of wheat and sorghum after sequential exposures to hydrogen fluoride

Wheat Triticum aestivum L. cv. Chris and two sorghum hybrids ( Sorghum sp. DeKalb C44C (DK) and Northrup King 222A (NK)) were exposed to hydrogen fluoride (HF) during three successive 3-day periods. The average concentrations of HF in each period were about 1·6 or 3·3 μ gFm −3 , and eight permutations of these levels were used in addition to a control (no HF). Measures of growth and yield and of fluoride (F) in the plant were taken immediately after the exposure period and again at harvest maturity to determine whether successive exposures to HF acted independently. Accumulation of F was related to the average concentration of HF over the entire exposure period by a second degree equation for wheat and the DK sorghum hybrid and a first degree equation for the NK hybrid. Growth and yield of wheat were not related to the mean concentration of HF in all exposures but to a weighted contrast between the first period and later two periods. Yield of the DK hybrid (the more resistant with reference to foliar injury) was not affected by HF, but yield of the NK hybrid was related to concentration of HF by a weighted mean of the second and third exposures. Exposures during anthesis were most effective with respect to HF-induced effects on yield. Anthesis occurred during the first exposure period in wheat and during the third exposure period in sorghum. The concentrations of HF during these periods, for the respective species, were most heavily weighted with reference to effects on yield.

Patterns of Fluoride accumulation and growth reduction exhibited by Douglas Fir in the vicinity of an aluminum reduction plant

Observed injury to vegetation in the vicinity of an aluminum reduction plant prompted an extensive quantitative analysis of fluoride accumulation in needles of Douglas fir and the associated effect on annual growth. Experimental trees were systematically selected using a grid system, 1- to 4-year old needles were collected for fluoride analysis, and tree corings were made. Correlations were then established between fluoride concentrations in needles and annual growth increments, wind pattern, distance from the fluoride source, and hydrogen fluoride concentrations in aerial effluents. Fluoride concentrations in leaves ranged from background levels in sheltered sites to over 500 mg kg −1 in a critical area where growth reduction coincidentally reached 72%. In some sites visible fluoride symptoms and over 40% growth reduction occurred in trees which were accumulating fluorides below ‘injury threshold levels’. This suggests a need to reconsider safe levels or that a case of synergism between HF and SO 2 exists in the study area.

Identification of two forms of fluorine in tissues of rats inhaling hydrogen fluoride

Nonionizable fluorine has been detected in the plasma of several species including the human, however, the exact nature and source of this fluorocompound(s) remain unknown. In the current investigation, the fluoride ion sensitive electrode was employed to determine the fluoride content of ashed (total F) and unashed (ionic F−) tissues of rats exposed to hydrogen fluoride (HF). Total fluorine concentration consistently exceeded ionic fluoride concentration in tissues of HF-exposed rats, suggesting the presence of fluorine in unashed tissue which did not respond to the F− ion sensitive electrode. The concentration of this nonresponding fluorine fraction, termed the ΔF fraction, was estimated by subtracting the ionic F− from the total F concentration of each sample. Pulmonary and plasma ΔF concentrations increased with time following whole body inhalation exposure to HF. It was possible to separate ΔF from ionic F− by calcium phosphate adsorption, indicating that the ΔF fraction consists of nonionizable fluorine. Upon Sephadex G-25 gel chromatography, plasma ΔF migrated near the bed volume, providing evidence that it is of low molecular weight. Finally, a strong correlation ( r = 0.99, p < 0.01) between plasma ΔF concentration and airborne HF concentration was observed, indicating that inorganic fluoride (as HF) is the ultimate source of the low-molecular-weight, nonionizable fluorine species present in tissues of HF-exposed rats.

Dry Scrubbing of Aluminum Cell Gases: An Index for System Performance

To evaluate the effectiveness of HF/alumina contact in a dry scrubber, the conventional scrubbing efficiency is inadequate because of its dependency on many parameters, including alumina feed rate. A semi-empirical expression called the “scrubbing index” is shown to be an appropriate measure. The scrubbing index expresses the extent of scrubbing achieved per unit of alumina feed rate. For a given alumina type and scrubber contacting design, the index appears to be constant and independent of alumina feed rate and hydrogen fluoride concentration in the raw cell gas. It can thus be used to characterize a given scrubbing system and predict its performance with a given alumina type. The derivation of the index and its application to a vertical-stud Soderberg dry scrubbing system is described.

The uptake of hydrogen fluoride by a forest

A mathematical model of hydrogen fluoride (HF) deposition and accumulation of fluoride in a Eucalyptus rostrata forest has been developed. The model is based on tree physiology and meteorological principles. The data base for the model was derived from a literature survey of the physiological characteristics of E. rostrata and similar eucalyptus species and from current knowledge of meteorological processes in plant canopies. Comparison of the mathematical simulations with measurements in the vicinity of a source of HF (an aluminium reduction plant) shows that (1) the pattern of seasonal fluoride accumulation in leaves agrees with that seen in the field, and (2) the vertical pattern of accumulation inside tree leaves agrees with field observations. The simulations indicate that 50% of the released HF was deposited within 81 km of the source and that the concentration of HF in the air 81 km from the source was reduced to 2% of the concentration 1 km from the source. However, a very large forest area (20 600 km 2) was required to achieve these reductions.

Regional deposition and absorption of inhaled hydrogen fluoride in the rat

The regional deposition of inhaled hydrogen fluoride (HF) was investigated by drawing known amounts of this irritant gas through the surgically isolated upper respiratory tract of anesthetized rats, while each animal respired HF-free room air through an endotracheal tube. At HF concentrations ranging from 30 to 176 mg F/m 3, greater than 99.7% of the HF drawn into the upper respiratory tract was removed from the airstream during passage through that site. Plasma fluoride concentrations were significantly elevated by this upper respiratory tract exposure to HF and were highly correlated with airborne HF concentrations ( r (8) = 0.98, p < 0.01). For comparative purposes, intact anesthetized rats were subjected to nose-only exposure to 63 mg F/m 3 HF for 1 hr. Both pulmonary and plasma fluoride concentrations were significantly elevated over control levels by nose-only exposure; however, pulmonary fluoride concentrations in these rats were no higher than plasma fluoride concentrations, providing little evidence that airborne HF penetrates to the lungs of rats respiring normally. These results indicate that in the anesthetized rat virtually all inhaled HF deposits in the upper respiratory tract from which it may be absorbed and/or translocated to other sites, e.g., the gastrointestinal tract, where systemic absorption may occur.

Application of a CW helium neon laser for measurement of gaseous hydrogen fluoride concentration

The concentration of gaseous hydrogen fluoride in air can be measured by the use of a close coincidence between the 3P4−2s2 cascade cw helium neon laser line and the 1R5 hydrogen fluoride absorption line. A nearby cw HeNe laser line (3p2–2s2) is not absorbed by hydrogen fluoride and may be used to compensate for transmission losses in a long-path measurement system. Most of the HFv=0 tov=1 absorption lines lie in a region in which there is strong attenuation caused by atmospheric water vapour, but the 1R5 line is almost free of interference from H2O, CO2 or CO.

Accumulation of fluoride by the soybean (Glycine maxL. Merrill var Dare) part I: Visible injury and related effects on seed yield

Abstract Soybeans (Glycine max L. Merrill var Dare) showed moderate resistance to leaf chlorosis and necrosis following extended exposures (109 days) to hydrogen fluoride concentrations of 2.0 μgHFm‐3 to 16. 1μg HF m‐3, inclusive (ECt2 = 400μg HF m‐3‐d ECt50 = 1500 μg HF m‐3‐d. Seed production was reduced at the lowest level of exposure and occurred with negligible visible injury to leaves. Pack and Sulzbach (1976) have suggested that the latter may result from effects on pollen production or germination, which is supported by these findings. In addition to reduced yields, seed production in fumigated plants was significantly retarded. Delays in maturityranged from an estimated one to two weeks (at 1.0 μg HF m‐3) to 6 weeks (at 16 μg HF m‐3).

Application of a CW chemical laser for remote pollution monitoring and process control

The measurement of the concentration of gaseous hydrogen fluoride in the exhaust of an aluminum plant by resonance absorption of the radiation of a cw chemical HF laser is reported. The HF concentration has been evaluated taking into account the simultaneous absorption of water vapor and carbon dioxide at the HF laser frequencies. The absorption cross sections for H2O and CO2 at the HF laser lines have been determined in laboratory experiments.

Effect of Hydrogen Fluoride and Hydrogen Chloride on Pollen Tube Growth and Sodium Fluoride on Pollen Germination in ‘Tilton’ Apricot1

Abstract Fumigations with hydrogen fluoride (HF) decreased in vivo pollen tube growth of ‘Tilton’ apricot (Prunus armeniaca L.). Both tube lengths and percent of styles with pollen tubes that reached the base of the style were adversely affected more by high HF concentration for a short time than by low concentration for a longer time. Pollen germination was unaffected on agar containing sodium fluoride. Fumigations with hydrogen chloride had no effect on pollen tube growth at concentrations from 0.05 to 0.75 mg Cl/m3 and durations of exposure from 8.5 to 72 hours.

Fluoride Susceptibility of Tomato Plants as Affected by Magnesium Nutrition1

Abstract Tomato plants (Lycopersicon esculentum Mill. cv. Bonny Best) grown in sand culture and provided with a complete nutrient solution or solutions containing sub- or supraoptimal Mg concentrations were fumigated with hydrogen fluoride (HF) at 5.0 or 9.7 μg F/m3 for 7 days. The severity of HF-induced chlorosis on apical and medial leaves was enhanced in Mg-deficient plants and suppressed in plants grown at the highest level of Mg. Foliar accumulation of fluoride (F) from exposure to the highest HF concentration was inhibited in plants provided the lowest and highest Mg levels. The presence of necrotic tissue probably suppressed the accumulation of F in Mg-deficient plants; however, it was not a factor in plants given supraoptimal Mg. The interactive effects of HF and Mg on foliar injury and F accumulation revealed that Mg-deficient plants were more susceptible and plants given excess Mg were more tolerant to HF than plants cultured on complete nutrient medium.

Development of gas-blending systems for calibration: application to hydrogen fluoride, arsine and phosgene in air.

Preparation of samples of known concentration of hydrogen fluoride, arsine and phosgene in air from 0.5 to 10 times the TLV is described. These are required to evaluate and calibrate analytical monitoring devices used for measuring these gases in work atmospheres. Dynamic gas-blending systems have been constructed and evaluated at the National Bureau of Standards for preparing these samples. Measurements to estimate the long term concentration stability of these gases are also included.