Acid Fog Research Articles

Features of a rare advection-radiation fog event

To investigate effects of atmospheric pollutants on fog nature, a comprehensive in situ observation project was implemented in the northern suburb of Nanjing, in December of 2006. For December 24–27 there occurred a heavy fog lasting 4 d in succession. This event is of rare characteristics, namely long persistence, high concentration, tall fog top, acid fog water and explosive growth. Detailed analysis along with the causes of the fog was presented. The evidence suggests that the fog was generated by nighttime radiative cooling, maintained and developed under effects of warm, wet advection. As a result, it is an advection-radiation fog event.

Leaching of cell wall components caused by acid deposition on fir needles and trees

Virgin fir forests have been declining since the 1960s at Mt. Oyama, which is located at the eastern edge of the Tanzawa Mountains and adjacent to the Kanto plain in Japan. An acid fog frequently occurs in the mountains. We collected throughfall and stemflow under fir trees and rainfall every week during January–December 2004 at Mt. Oyama to clarify the influence of acid fog on the decline of fir ( Abies firma) needles. In relation to throughfall and stemflow, d-mannose, d-galactose, and d-glucose are the major neutral sugar components; only d-glucose is a major component of rainfall. The correlation coefficient between the total neutral sugars and uronic acid (as d-galacturonic acid), which is a key component of the cross-linking between pectic polysaccharides, was high except for rainfall. The leached amount of calcium ion, neutral sugars, uronic acid, and boron is related to the nitrate ion concentration in throughfall. Results of a laboratory exposure experiment using artificial fog water simulating the average composition of fog water observed at Mt. Oyama (simulated acid fog: SAF) on the fir seedling needles also shows a large leaching of these components from the cell walls of fir needles. The leaching amount increased concomitantly with decreasing pH of the SAF solution. We also observed that a dimeric rhamnogalacturonan II-borate complex (dRG-II-B) that exists in the cell wall as pectic polysaccharide was converted to monomeric RG-II (mRG-II) by the leaching of calcium ion and boron. Results not only of field observations but also those of laboratory experiments indicate a large effect of acid depositions on fir needles.

무도장 교량에 사용되는 내후성강재의 부식 및 피로거동에 미치는 산성안개의 영향

The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in un-coated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

Growth and physiological responses of beech seedlings to long-term exposure of acid fog

Seven-year-old beech seedlings ( Fagus crenata) were exposed to simulated acid fog (SAF) at pH 3 or pH 5 (as control) prepared by adding a 2:1:1 mixture (molar ratio) of nitric acid, ammonium sulfate, and sodium chloride to ultrapure water from September 2004 to July 2006 in a mobile fog chamber. In comparison to control seedlings, seedlings from the pH 3 treatment displayed inferior plant height, stem diameter, number of leaves, and dry matter production, but greater leaf area. Furthermore, exposure to SAF induced early falling of leaves with a nearly two-times-greater normalized leaf number index than control. The starch levels in the stems of seedlings of the pH 3 treatment were much lower than those of control at the harvest. The acid fog-induced reduction of the starch accumulation is considered to occur mainly because of fewer leaves during the growth phase. Results of laboratory experiments demonstrate that the amount of base cations leached from the beech leaves increased with decreasing pH of SAF; the leaching amount of calcium ion from the beech was high relative to that of conifers such as fir and cedar. These results imply that chronic acid fog exposure suppresses growth and physiological activity of beech seedlings.

A case of acute pulmonary edema induced by inhalation of acid fog of nitric acid

硝酸吸入可导致急性呼吸道损伤,临床上可以表现为轻微的上呼吸道刺激症状、非心源性肺水肿,甚至死亡.硝酸吸人性肺水肿为极其罕见的病例,目前还未发现治疗硝酸吸入性肺水肿的有效方法[1-2]。

An Analysis on the Environmental Regulation Policy Instrument Affecting on the Air Environment: Focused on the Policy Instrument for the Acid Fog

An Analysis on the Environmental Regulation Policy Instrument Affecting on the Air Environment: Focused on the Policy Instrument for the Acid Fog

Chemistry of fogs at Agra, India: Influence of soil particulates and atmospheric gases

Fog water samples were collected in the months of December and January during 1998-2000 at Agra, India. The samples were analyzed for pH, major anions (F(-), Cl(-), SO(4) (2-), NO(3) (-), HCOO(-) and CH(3)COO(-)), major cations (Ca(2+), Mg(2+), Na(+) and K(+)) and NH(4) (+) using ion chromatography, ICP-AES and spectrophotometer methods, respectively. pH of fog water samples ranged between 7.0 and 7.6 with a volume weighted mean of 7.2, indicating its alkaline characteristic. NH(4) (+) contributed 40%, SO(4) (2-) and NO(3) (-) accounted for 28%, while Ca(2+), Mg(2+), Na(+) and K(+) accounted for 16% of the total ionic concentration. The ratios of Mg(2+)/Ca(2+) and Na(+)/Ca(2+) in fog water indicates that 50-75% of fog water samples correspond to the respective ratios in local soil. Significant correlation between Ca(2+), Mg(2+), Na(+) and K(+) suggests their soil origin. The order of neutralization, NH(4) (+) (1.4) > Ca(2+) (0.28) > Mg(2+) (0.12), indicates that NH(4) (+) is the major neutralizing species. Fog water and atmospheric alkalinity were also computed and were found to be 873 and 903 neqm(-3), respectively. Both of these values are higher than values reported from temperate sites and thus indicate that at the present level of pollutants, there is no risk of acid fog problem. The study also shows that the alkaline nature of fog water is due to dissolution of ammonia gas and partly due to interaction of fog water with soil derived aerosols.

Mars and mine dumps

Abundant sulfates appear to exist on the surface of Mars and have commonly been attributed to a planet‐wide volcanogenic ‘acid fog’—where clouds of acid mist react directly with surface rocks or acidify surface waters—from which the sulfates precipitated [e.g., Clark and Baird, 1979]. In particular, Meridiani Planum, a plain located just south of the Martian equator, hosts many sulfate minerals.Squyres et al. [2004, 2006] and Squyres and Knoll [2005] hypothesized that the sulfate minerals there, particularly acid sulfates such as jarosite, precipitated from high concentrations of sulfuric acid in flowing and standing water and groundwater. However, such explanations are problematic, because magnesia and alkali‐bearing minerals in the basaltic regolith should have been able to neutralize sulfuric acid rapidly, making precipitation of acid sulfates such as jarosite impossible.

Mineralogy and evolution of the surface of Mars: A review

We review the mineralogy of the surface of Mars, using data from various sources, including in situ characterisations performed by landers, remote observations from orbit, and studies of the SNC meteorites. We also discuss the possible alteration processes and the factor controlling them, and try to relate the mineralogical observations to the chemical evolution of the surface materials on Mars in order to identify the dominant process(es). Then we try to describe a possible chemical and mineralogical evolution of the surface materials, resulting from weathering driven by the abundance and activity of water. Even if weathering is the dominant process responsible for the surface evolution, all observations suggest that it is strongly affected locally in time and space by various other processes including hydrothermalism, volcanism, evaporites, meteoritic impacts and aeolian erosion. Nevertheless, the observed phases on the surface of Mars globally depend on the evolution of the weathering conditions. This hypothesis, if confirmed, could give a new view of the evolution of the martian surface, roughly in three steps. The first would correspond to clay-type weathering process in the Noachian, under a probable thick H 2O/CO 2-rich atmosphere. Then, during the Hesperian when water became scarcer and its activity sporadic, linked to volcanic activity, sulfate-type acidic weathering process would have been predominant. The third period would be like today, a very slow weathering by strongly oxidising agents (H 2O 2, O 2) in cold and dry conditions, through solid-gas or solid-films of water resulting frost-thaw and/or acid fog. This would favour poorly crystalline phases, mainly iron (oxy) hydroxides. But in this scenario many questions remain about the transition between these processes, and about the factors affecting the evolution of the weathering process.

Long-Term Observation of Fogwater Composition at two Mountainous Sites in Gunma Prefecture, Japan

We made serial observations on acid fog at Mt. Akagi and Mt. Haruna, Japan for 5 years. The altitudes of the sampling sites were 1500 m (Mt. Akagi) and 1200 m (Mt. Haruna) above sea level, and the sites were approximately 30 km apart. The average liquid water content (LWC) at Mt. Akagi and Mt. Haruna was 74 mg m−3 and 63 mg m−3, respectively. The pH of fogwater was 2.72–7.14 (mean 3.71) at Mt. Akagi and 2.94–6.58 (mean 3.73) at Mt. Haruna. Our long-term observations indicate that there was no significant difference in the chemical components in fogwater at both sites except for ammonium ion. However, there were some cases where the chemical components of fogwater at each site were differed remarkably even in the concurrent fog event. Nitrate and sulfate ions contributed to acidification of fogwater at Mts. Akagi and Haruna and 95% of sulfate ion in the fogwater originated from air pollution. Ammonia gas in the air was the main neutralizer of acidity in fogwater. When absorption of excessive nitric acid gas over ammonia gas in the air occurred, the pH of fogwater was lowered. Our back trajectory analysis indicated that the fogwater at Mt. Akagi was mainly affected by an air mass from the Kanto Plain, including Tokyo, while the fogwater at Mt. Haruna was influenced by an air mass from large, western cities, such as Nagoya and Osaka, as well as Tokyo.

Fog and rain water chemistry at Mt. Fuji: A case study during the September 2002 campaign

Measurements of fog and rain water chemistry at the summit of Mt. Fuji, the highest peak in Japan, as well as at Tarobo, the ESE slope of Mt. Fuji in September 2002. The pH of fog and rain water sampled at Mt. Fuji varied over a range of 4.0–6.8. Acidic fogs (pH < 5.0) were observed at the summit when the air mass came from the industrial regions on the Asian continent. The ratio of [SO 4 2−]/[NO 3 −] in the fog water was lower at Tarobo than at the summit. High concentrations of Na + and Cl − were determined in the rain water sampled at the summit, possibly because of the long-range transport of sea-salt particles raised by a typhoon through the middle troposphere. The vertical transport of sea-salt particles would influence the cloud microphysical properties in the middle troposphere. Significant loss of Mg 2+ was seen in the rain water at the summit. The concentrations of peroxides in the fog and rain water were relatively large (10–105 μM). The potential capacity for SO 2 oxidation seems to be strong from summer to early autumn at Mt. Fuji. The fog water peroxide concentrations displayed diurnal variability. The peroxide concentrations in the nighttime were significantly higher than those in the daytime.

Acid-fog deposition at Kilauea volcano: A possible mechanism for the formation of siliceous-sulfate rock coatings on Mars

On the summit of Kilauea volcano, sulfur dioxide, which is continuously emitted from Halemaumau crater and rapidly sequestered into sulfuric-acid–rich aerosol entrained in the prevailing trade winds, is subsequently precipitated as acid fog immediately downwind from Kilauea caldera in the Kau Desert. The characteristic pH of surface tephra deposits is <4.0 in Sand Wash, a region of nearly continuous, acidic aerosol fallout immediately southwest of the caldera. Vertical exposures of unconsolidated tephras of the Keanakakoi Ash found within fissures and small, dry gullies are coated with thin rock coatings of amorphous silica and jarosite. These rock coatings are formed via an evaporative mechanism whereby acidic pore fluids, circulating in the upper few meters within the highly porous tephra, are wicked toward the walls of the gullies. Geochemical modeling of the rock coating formation process implies that the sulfate formation via evaporation occurs subsequent to minimal interaction of acidic pore fluids with the basaltic tephra. This also suggests that the cycle from acid-fog fallout to precipitation of the siliceous-sulfate rock coatings must occur quite rapidly. Acid-fog deposition of sulfate and silica at Kilauea may provide one mechanism for the origin of jarosite-bearing outcrops on Mars.

Laboratory‐simulated acid‐sulfate weathering of basaltic materials: Implications for formation of sulfates at Meridiani Planum and Gusev crater, Mars

Acid‐sulfate weathering of basaltic materials is a candidate formation process for the sulfate‐rich outcrops and rocks at the MER rover Opportunity and Spirit landing sites. To determine the style of acid‐sulfate weathering on Mars, we weathered basaltic materials (olivine‐rich glassy basaltic sand and plagioclase feldspar‐rich basaltic tephra) in the laboratory under different oxidative, acid‐sulfate conditions and characterized the alteration products. We investigated alteration by (1) sulfuric‐acid vapor (acid fog), (2) three‐step hydrothermal leaching treatment approximating an “open system,” and (3) single‐step hydrothermal batch treatment approximating a “closed system.” In acid fog experiments, Al‐, Fe‐, and Ca‐sulfates and amorphous silica formed from plagioclase‐rich tephra, and Mg‐ and Ca‐sulfates and amorphous silica formed from the olivine‐rich sands. In three‐step leaching experiments, only amorphous Si formed from the plagioclase‐rich basaltic tephra, and jarosite, Mg‐, and Ca‐sulfates and amorphous silica formed from olivine‐rich basaltic sand. Amorphous silica formed under single‐step experiments for both starting materials. On the basis of our experiments, jarosite formation in Meridiani outcrop is potential evidence for an open system acid‐sulfate weathering regime. Waters rich in sulfuric acid percolated through basaltic sediment, dissolving basaltic phases (e.g., olivine) and forming jarosite, other sulfates, and iron oxides. Aqueous alteration of outcrops and rocks on the West Spur of the Columbia Hills may have occurred when vapors rich in SO2 from volcanic sources reacted with basaltic materials. Soluble ions from the host rock (e.g., olivine) reacted with S to form Ca‐, Mg‐, and other sulfates along with iron oxides and oxyhydroxides.

Effects of complex stress of chronic acid fog exposure with rhizosphere aluminum on nutrient status in Abies firma seedlings

We exposed momi fir (Abies firma Sieb. et Zucc.) seedlings to simulated acid fog of pH 3.0 for about 3 years (from July 1999). During the last year of acid fog exposure, half of the seedlings were subjected to rhizosphere Al stress (complex stress) and the nutrient status of seedlings was determined. Chronic acid fog exposure decreased Fe and Zn concentrations in current-year and 1-year needles, and Al in 1-year needles, but had little effect on major element concentrations. Aluminum treatment had a broad impact on nutrient status in fine roots and needles. In fine roots, increases in Al and Cu concentrations and decreases in B, Mn, and Zn concentrations were observed. In 1-year needles, Al treatment increased Al, B, and Mn concentrations and decreased Cu concentration. The complex effect of acid fog with aluminum on nutrient status was relatively slight. These results show that changes in nutrient status under chronic acid fog exposure and/or Al stress are induced before the decline of photosynthesis in momi fir seedlings, mainly due to Al stress.

Modelling massive sulphate aerosol pollution, following the large 1783 Laki basaltic eruption

The climatic impact of volcanic eruptions depends mainly on the amount of sulphur-rich gases released into the stratosphere. These are rapidly converted to sulphate aerosols, which result in cooling of the lower troposphere and warming of the lower stratosphere. These gases are retained in the stratosphere and then concentrated by atmospheric processes, forming acid fog near the Earth's surface, with potentially dramatic environmental consequences on plants, animals and humans. We have modelled such emissions in the case of the unusually large 1783–1784 basaltic fissure eruption of Laki (Iceland), using an Atmospheric General Circulation Model. Results show good agreement with historical observations, such as typical time taken by individual pulses to reach continental Europe or geographical extent of the deadly haze that covered much of the northern hemisphere. The model could be adjusted to predict the climatic consequences of very large eruptions, up to the scale of massive flood basalts, and test the proposal that these are the main agent in most mass extinctions of life on Earth.

Effects of chronic acid fog exposure with soil acidification or nitrogen loading on nutrient status in Abies firma seedlings

To clarify the nutrient status in momi fir (Abies firma Sieb. et Zucc.) seedlings under complex stress conditions of acid fog with soil acidification or nitrogen loading, we exposed seedling shoots to simulated acid fog (pH 3) and simultaneously loaded the soil with acid or excess nitrogen for 17 months. Proton and nitrogen loading reduced K concentration in soil, but these treatments had little effect on the nutrient status of fine roots in momi fir seedlings. Acid fog exposure resulted in reduced concentrations of Mg, Al, and Fe in current-year needles and Mg, Al, Cu, Fe, and Zn in 1-year-old needles. The complex effects of acid fog exposure with proton or nitrogen loading on nutrient status were relatively slight. However, elements such as Al and Cu notably reflect the effects of proton loading. These results show that the nutrient status of trace elements, rather than major elements, in needles of momi fir seedlings is sensitive to exposure to acid fog or proton loading.

人工曝露装置を用いた酸性霧，ガス及びエアロゾルによる金属溶出及び各イオン表面挙動

人工曝露装置を用いた酸性霧，ガス及びエアロゾルによる金属溶出及び各イオン表面挙動

Response of gas exchange rates in Abies firma seedlings to various additional stresses under chronic acid fog stress

In order to clarify the chronic influence of acid fog on the gas exchange rates of momi fir (Abies firma Sieb. et Zucc.) trees, we exposed them to simulated acid fog (pH 3) for 3 years. The composition of the acid fog was similar to that observed in a region where momi fir trees have been declining, and it contained organic acids. We then treated the firs with various additional stresses, such as drought, low temperature, fine root cutting, ozone exposure, soil acidification, nitrogen load, and rhizosphere aluminum stress. Under chronic exposure to acid fog, the momi fir seedlings exhibited a pattern of stomatal behavior whereby they excessively opened in summer and closed in winter. Furthermore, the stomata of these seedlings tended to open during drought stress, and their needles were visibly injured after ozone exposure. The net photosynthesis rates of the seedlings exposed to acid fog were regulated by their stomatal aperture, rather than directly by acid fog. These results suggest that acid fog exposure disturbs the control of stomatal function in the momi fir seedlings. In addition, we found that chronic acid fog exposure suppressed the decrease in net photosynthesis rate, due to its nitrogen load.

Acid‐sulfate weathering of synthetic Martian basalt: The acid fog model revisited

The acid fog model has received considerable attention as a model of soil formation on Mars. Previous evaluations of this model have focused on experimental weathering of terrestrial basalt samples. However, these samples differ significantly from what now is thought to be typical of Martian basalt. The acid fog model is tested here using synthetic basaltic analogs derived from Mars Pathfinder soil and rock compositions. Reaction of synthetic basalt with various acidic solutions and subsequent evaporation has led to the formation of several putative secondary mineral phases. Many of these phases were not produced in prior experimental studies aimed at aqueous interactions on Mars. Of these alteration phases, Mg, Fe, Ca, and Al sulfates were identified. In addition, secondary ferric oxide phases formed via rapid Fe oxidation under relatively high pH levels buffered by basalt dissolution. Amorphous silica is a ubiquitous product in these experiments and has formed by precipitation from solution and by the dissolution of minerals and glasses leaving behind leached surface layers composed of residual silica. The secondary products formed in these experiments demonstrate the importance of primary mineralogy when testing models of aqueous interactions on Mars. New constraints are placed on both the reactivity of primary basalt and the secondary mineralogy present at the Martian surface.

Effects of Acid Fog on Tree Physiology.

Effects of Acid Fog on Tree Physiology.