Fog Samples Research Articles

Ion chromatographic determination of major ions in fog samples

An ion chromatographic configuration including column switching and gradient elution was used for the determination of major cations (Na +, Ca 2+, Mg 2+, K +, NH 4 +) and anions (Cl −, NO 2 −, NO 3 −, SO 4 2−) in fog water samples. The results showed that ion-exchange chromatography compares very well with the more generally used spectroscopic techniques for cation determinations. Detection limits range from 6 μg/l (Na +) to 40 μg/l (K +). Precise and accurate analysis of natural fog water samples can be performed with cost and time savings in comparison with other techniques.

Detection of Infectious Tomato Mosaic Tobamovirus in Fog and Clouds

Tomato mosaic tobamovirus (ToMV) was detected by enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction-blot hybridization (RT-PCR-BH) in cloud samples collected from the summit of Whiteface Mountain, NY, and in fog samples from two collection sites along the coast of Maine. The virus was subsequently transmitted to Chenopodium quinoa from a composite of RT-PCR-BH-positive concentrates. There was no apparent relationship between the presence of ToMV and sample collection date, volume, or pH. The RT-PCR products of three cloud and fog samples and one deionized water sample were identical to one another and to a stream water isolate of ToMV from Whiteface Mountain based on nucleotide sequencing of a 347-bp fragment within the coat protein gene and 99.1 and 72.9% similarity to ToMV-L and tobacco mosaic virus-vulgare, respectivelv.

Fogwater Chemistry at a Mountainside in Japan

Abstract Fogwater had been observed for 4.5 years from July 1988 to December 1992 at the midslope of Mt. Oyama at the southwest of the Kanto plains. Rainwater, aerosol, and gases had been also collected and analyzed at the fog sampling station to investigate the characteristics and acidification mechanism of fogwater. The pH of fogwater ranged from 2.61 to 7.00 and the fog with very low pH values and high ion and aldehyde concentrations were frequently observed in spring and summer. The fogwater at the site was acidified primarily by nitric acid gas absorbed in fogwater and the acid fraction of most of the fogwater ranged from 0.3 to 0.01. The acidity of fogwater is controlled by the amount of the acidic pollutants in the atmosphere, the concentrations of the neutralizing components for the acidic fogwater, primarily NH3 gas concentration, the liquid water content in air, and the distance between the sampling station and the lowest altitude of the fog in upslope fog.

Sulfur dioxide oxidation in atmospheric water: role of iron(II) and effect of ligands

Laboratory experiments were conducted with fogwater collected in the urban area of Dubendorf, Switzerland, and with synthetic solutions designed to simulate some of the chemical features of fogwater. In fogwater that contained higher concentrations of organic pollutants (i.e., DOC), S(IV) oxidation rates were significantly lower than those expected for Fe-catalyzed S(IV) oxidation by oxygen. It is suggested that organic species that can scavenge radical intermediates (e.g., acetate, formate), form complexes with Fe(III) (e.g., oxalate), or form adducts with S(IV) (e.g., formaldehyde) are responsible for the observed inhibition. Fe(III) reduction was also observed in filtered fog samples in the dark

Studies on the occurrence and distribution of wood smoke marker compounds in foggy atmospheres

AbstractFog water and interstitial air samples were collected simultaneously and analyzed for methoxylated phenols, which have been previously reported as incomplete combustion products from wood lignin. The purposes of this study were to ascertain if these methoxylated phenols could be detected in fog sampled in residential areas and to determine the distribution of the compounds between fog droplets and interstitial air. The fog water was collected with a Teflon® filament fog collector and filtered through a 0.2‐μm filter before extraction and GC analysis. Vapor samples were collected using a dichotomous sampler to separate fog droplets from interstitial air; the organic vapors were collected on polyurethane foam. Guaiacol, 4‐methylguaiacol, and syringol were the most commonly found among the 16 methoxylated phenols confirmed in fog samples. The distributions between air and water approximately followed Henry's law, suggesting that previously reported enrichments into fog water are related to analyte hydrophobicity, described by either the octanol/water partition coefficient or the water solubility.

Predator: non-predator ratios in beetle assemblages.

In common with samples from less taxonomically constrained studies, significant correlations exist between the numbers of predatory and non-predatory species in assemblages of terrestrial beetles. Under logarithmic transformation the relationship can be described reasonably well by a straight line. Explanations for predator: non-predator relationships based on the dynamics of trophic interactions (e.g. competition for prey types or enemy-free space) seem insufficient to explain this pattern, because within beetle assemblages the necessary interactions are so few. Of other proposed determinants, those based on the relationship of local and regional species pools, on energetics, or on non-trophic factors seem the most plausible candidates for explaining proportionality amongst beetles. Much of the deviation from the overall pattern can be accounted for by sampling method and latitude. Temperate samples have a higher proportion of predatory species than tropical, whilst litter and pitfall trap samples have higher proportions of predatory species than Malaise trap and fogging samples.

The Quality of Fog Water Collected for Domestic and Agricultural Use in Chile

Abstract One exciting new application of meteorology is the prospect of using high-elevation fogs as an and land's water resource. This has now become reality in northern Chile where a pilot project has used 50 fog collectors to generate an average of 7200 1 of water per day during three drought years. The chemical composition of the fog water is of primary importance and is examined in this paper. A small, carefully cleaned fog-water collector was used at the site (elevation 780 m) to study the incoming fog (cloud). The ion and trace-element concentrations met Chilean and the World Health Organization's (WHO) drinking-water standards. The pH values, however, were at times extremely low. Samples from 1987 and 1988 were consistent with those from the larger dataset in 1989. The lowest observed pH was 3.46. The acidity was associated with high concentrations (89%) of excess sulfate in the 15 fog-water samples (based on Cl− as the seawater tracer element). The NO3−/SO4− equivalents ratio for the fog samples ...

A field study on chemistry, S(IV) oxidation rates and vertical transport during fog conditions

An extensive fog study was carried out in the central plateu of Switzerland. Ninety-seven fog samples were collected along with aerosol filter and cascade impactor samples, and measurements of O 3, SO 2, NO, NO x , PAN, temperature, and wind speed and direction. Maximum levels in fogwater were 4.3, 4.4., 0.033, 1.7, 0.5, 0.024 and 9.2 mmol ℓ −1 for Cl −, NO 3 −, NO 2 −, SO 4 2−, S(IV), oxalate and NH 4 +, respectively. pH varied between 2.9 and 7.1. Sixteen additional elements were determined in the fog samples by ICP. The sum of the concentrations of SO 4 2− and S(IV) agreed very with the total sulfur concentration as determined by ICP. A substantial excess of S(IV) (up to 0.2 mmol ℓ −1) compared to Henry and acid-base equilibrium calculations was found, which can probably be attributed to complex formations with aldehydes. S(IV) oxidation rates of up to 650 nmol ℓ −1 s −1 with ozone and of up to 100 nmol ℓ −1 s −1 with NO 2 were calculated. S(IV) oxidation due to PAN, NO 2 − and Fe(III) was of minor importance. A substantial fraction of the major ions was present in the intersitial aerosol (aerosol particles < 4 μm) even during fog conditions. High correlations were found for NH 4 +, NO 3 2−. From their ratios in the fog water and the aerosol (< 4 μm) it could be concluded that at least 40% of NO 3 − and 20% of NH 4 + in fog water was due to gas phase scavenging. Increasing concentrations in fog water were found during fog dissipation. Concentrations decreased with increasing height. A vertical transport model including turbulent diffusion and droplet sedimentation is introduced, which matches the experimental data of this vertical profile.

An automatic station for fog water collection

An automatic fog sampling station is presented in this paper which is suited for unattended operation. This system, designed to meet the requirements of our particular sampling protocol, is comprised of an optical fog detector which senses the light backscattered by the droplets, a rotating string collector, a sampling storage/fractionation unit and a computer which drives the operations of the station and acquires the sampling information. The sampling operational problems are discussed, and the results from an extended fog sampling period are reported.

Analysis of fog samples for PCDD and PCDF

Trace levels of PCDD and PCDF were detected in fog samples collected in Dübendorf, Switzerland. The more chlorinated, less toxic isomers predominated. Octachlorodibenzodioxin (OCDD) was the most abundant congener at 0.3-3 1 ng/L. No 2,3,7,8- TCDD or TCDF were detected. Congener class profiles were similar to those reported for air and rain samples, suggesting similar sources. Higher PCDD/PCDF levels in fog compared with reported levels in rain may be due to enhanced particle scavenging by fog.

Determination of mono- and divalent cations and anions in small fog samples by ion chromatography

The application of ion chromatography to the determination of inorganic and organic anions and mono- and divalent cations in fog samples with a total volume of 1 ml is described. After filtration, the samples were split for four different ion chromatographic injections, all by autosampler. Detection limits were below 20 ppb for all ions. The pH was determined by means of a micro pH meter. The calculated ion balances agreed to within 16% or better in all instances. Adding glycerine did not enhance the stability of sulphite during sampling but enhanced the stability of sulphite in fog samples against oxidation by hydrogen peroxide in laboratory experiments.

Aliphatic and polycyclic aromatic hydrocarbons in urban rain, snow and fog

Rain, snow and fog samples have been collected at an urban site in Switzerland. Concentrations of n-alkanes and polycyclic aromatic hydrocarbons (PAH) were determined in the particulate (⩾ 0.2 μm) and filterable phases. The n-alkanes in the particulate phase were characterized by a carbon preference index (CPI), in the range of C 21–C 33, of 7.1 in summer rain compared to 2.1 in winter rain. n-Alkanes with a CPI of 1.2 occurred in the filtrate of several samples. The presence of these highly water-insoluble n-alkanes in the filterable fraction suggests the formation of intermolecular associations (clusters, aggregates). The PAH patterns in the particulate phases resemble each other in snow, summer and winter rain, indicating similar sources and scavenging mechanisms. Variations in the concentrations of n-alkanes and PAH between seasons and between rain, snow and fog can be explained by the size of the associated particles and hydrometeors (rain droplet, snow flake, fog droplet) and the related scavenging efficiencies. The distribution coefficients obtained by field measurements have been applied to a scavenging model and to an equilibrium model taking hydrophobic partitioning into account.

Problems of fog sampling

Problems of fog sampling

Fog Chemistry at an Urban Midwestern Site

The Holcomb Research Institute is monitoring fog chemistry in Indianapolis, Indiana and at sites in and near the heavily industrialized Ohio River Valley. Results reported here indicate that fogs in this area can be strongly acidic, and that further studies are warranted. We report 1) the ionic composition of three fog events, samples collected in Indianapolis between December 1985 and February 1986, and 2) the pH of three additional events, samples collected between November 1985 and February 1986. (The volume of fog collected during the latter three events was insufficient for chemical analysis other than pH.) The pH of the fog samples ranged from 2.85 to 4.06; some of this fell within the range known to damage foliage and yield of some plant species. It has been demonstrated that even one exposure to highly acidic mists (pH par. delta 2.5) can damage certain crop species; hence, it is important to document the occurrence of any events having acidity near this level.

On the acidity of dew

Nightly dew samples were collected on Allegheny Mountain in southwest Pennsylvania in August 1983. The dew was found to be acidic, with meanpH∼4.0. Free H+comprised &gt;80% of the total acidity, and the composition approximated an H2SO4/HNO3mixture with average SO42−/NO3−mol ratio ∼1.3. The chemistry of the dew resembled that of rain at Allegheny, though the dew was generally more dilute. Atmospheric HNO3(g) was chiefly responsible for the dew NO3−. SO2was the source of ∼80% of the dew SO42−. The allocation of dew H+among atmospheric precursors was HNO3∼30%, SO2≥ 60%, aerosol H+≤ 10%. The most acidic dews were associated with wind from the west. Average deposition velocities (stated in centimeters per second) to dew were HNO3, 0.24; NO2, &lt;0.02; SO2, ∼0.04; aerosol SO42−, ∼0.02; aerosol NH4+, 0.024; and aerosol species, 0.02–1. Comparison of the HNO3deposition velocity with ten‐fold higher summer daytime values reveals a pronounced diurnal variation. The 0.24 cm/s value for HNO3may represent a maximum for any gas or submicron aerosol species whenever the atmosphere is strongly stable. Not all of the S(IV) in dew had been converted to SO42−by morning; thus the rate of oxidation must have been on a time scale of hours at nighttime ambient temperatures. In contrast, S(IV) in rain and fog samples was not evident. Deposition fluxes and cumulative deposition totals involving dew, rain, and settled fog water were compared. Rain proved by far the most important for deposition of all solute species, including acid.

Capillary gas chromatography determination of volatile organic acids in rain and fog samples

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCapillary gas chromatography determination of volatile organic acids in rain and fog samplesKimitaka. Kawamura and Isaac R. KaplanCite this: Anal. Chem. 1984, 56, 9, 1616–1620Publication Date (Print):August 1, 1984Publication History Published online1 May 2002Published inissue 1 August 1984https://doi.org/10.1021/ac00273a018RIGHTS & PERMISSIONSArticle Views584Altmetric-Citations106LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (570 KB) Get e-Alerts Get e-Alerts

Chemistry of mist and fog from the Los Angeles urban area

The incorporation of acids and other pollutants in mist and fog has been studied by collecting samples at ground level. The median concentration of H + for 20 mist samples was 248 μM, and for 10 fog samples, 478 μM. The corresponding two medians for other major ions were: NH + 4, 518 μM and 1580 μM; NO 3 −, 887 μM and 1110 μM; SO 4 2−, 219 μM and 292 μM. The mist and fog samples are NO 3 −-dominated (NO − 3/SO 2− 4 equivalents ⋍ 2) in contrast to Los Angeles rain data where NO − 3/SO 2− 4 equivalents ⋍ 0.6. These findings are in accord with the known high concentrations of gaseous nitrogen oxides and aerosol nitrate near ground level, and the nitrogen oxide and sulfur oxide emission patterns in this area.

Carbonyls in urban fog, ice fog, cloudwater and rainwater

Formaldehyde, acetaldehyde, propanal, acetone + acrolein, n-butanal, 2-butanone, n- pentanal, n-hexanal and benzaldehyde have been identified in fog, ice fog, mist, cloudwater and rainwater samples collected at urban locations in California (Los Angeles) and Alaska (Fairbanks). Formaldehyde concentrations, up to ~ 2 mg ℓ −1, were highest in urban fog and ice fog samples. Concentrations of other carbonyls occasionally approached or exceeded that of formaldehyde. The results are briefly discussed in terms of scavenging of gas-phase atmospheric carbonyls.

Measurements of temperature and degradation of pyrethroids in two thermal fogging machines, the swingfog and TIFA

AbstractThe losses of natural pyrethrins, bioallethrin, bioresmethrin and tetramethrin have been measured during thermal fogging using the Swingfog Model SN6 and the Lightweight TIFA. Fogs produced from kerosene solutions of the insecticides containing an internal standard were analysed by gas chromatography. Losses of natural pyrethrins, bioresmethrin and tetramethrin were less than the experimental error showing that these compounds did not degrade in either machine. Losses of bioallethrin were 3.1 and 5.5% in the Swingfog and TIFA respectively but these figures were possibly exaggerated slightly by inefficiencies in the fog sampling technique and it is doubtful if losses of this magnitude would be detected under field conditions.Whilst operating with odourless kerosene, the maximum temperatures recorded within the fogging heads were 120°C in the Swingfog with a flow rate of 351/h and 265°C in the TIFA with a flow rate of 951/h.

ON THE CHEMICAL COMPOSITION OF FOG AND CLOUD WATER

Abstract The partial chemical analysis of some ninety samples of fog and cloud water is reported. The fog samples were collected at four locations along the northeast coast of North America, and the cloud samples were obtained on Mount Washington, New Hampshire. It is found that the soluble nuclei are predominantly chlorides and sulfates. The chlorides are dominant in air with a recent trajectory over the sea, while the sulfate is always present. In many cases it appears that much of the sulfate is in the form of sulfuric acid.