Acid deposition at the summit of Mt. Fuji: Observations of gases,aerosols and precipitation in summer,1993 and 1994

Intensive observations of chemical species in aerosols, gases and other samples at the summit of Mt. Fuji and at Tarobo (at 1300m on the mountain'ts southern slope) was performed from July 28 to Aug. 3, 1993 and from July 25 to 30,1994. The most interesting observation was the abrupt increase in the sulfate concentration in aerosol collected in July, 1993 just after the typhoon (number 9306) passed the Japanese archipelago and the wind direction shifted from south to west. Chemical analysis indicated this aerosol was acidic. In contrast, the summit aerosol observed in 1994 was not acidic following a less dramatic rise in sulfate content. Back trajectory analyses were used to extrapolate from these measurement to an inventory of polluted air over the Asian Continent. The concentrations of gaseous SO₂ and HCl remained low during both observation periods, with some higher concentrations of NH₃.     

Chemical deposition to a high elevation red spruce forest

A preliminary analysis of O₃, SO₂, SO _inf4 ^sup2? , and total NO _inf3 ^sup? deposition to the red spruce forest on the summit of Whitetop Mountain, Virginia, illustrates uncertainties in analysis methodologies, establishes the relative importance of three deposition pathways, and suggests areas for further research. Results are presented here for an analysis of the dry, wet (precipitation), and cloud water deposition pathways for the four chemical species during a 26-day period in April and May 1986. Dry and cloud water depositions are estimated using available models along with air and cloud water chemistry measurements made at the summit. For water soluble species, depositions by precipitation and cloud interception are found to be comparable in magnitude, while dry deposition appears to be about an order of magnitude less. High levels of atmospheric O₃ lead to a large estimate of 03 deposition (on a mass flux basis) when compared to the estimated deposition of gaseous SO₂. This is in spite of the fact that computed SO₂ dry deposition velocities exceed those for O₃. Model uncertainties are large for both dry deposition velocity and cloud water flux computations, and some bias in computations probably exists because of the application of the models to a complex terrain situation. Field evaluation of the cloud water deposition model is of greatest priority because of the apparent relative importance of that deposition pathway.     

Fog and Precipitation Chemistry at Mt. Rokko in Kobe, April 1997-March 1998

Fog water and precipitation were collected and analyzed to study fog and precipitation chemistry. The research was carried out through one year from April 1997 to March 1998 at Mt. Rokko in Kobe. Higher fog occurrence and larger volume of fog water were observed in summer, corresponding to the trend of seasonal variation in precipitation amount. The annual mean pH value of fog water (3.80) was lower by ca. one pH unit than that of precipitation (4.74). The concentration of chemical species in fog water was ca. 7 times that in precipitation. The highest anion and cation concentrations were SO₄ ^2? and NH₄ ⁺ in fog water and Cl^? and Na⁺ in precipitation, although the Cl^?/Na⁺ equivalent ratio in both fog water and precipitation was almost the same value as that in sea water. It is considered that in the longest fog event, NH₄ ⁺ and nss-SO₄ ^2? in fog water mainly scavenged as (NH₄)₂SO₄, mainly derived from (NH₄)₂SO₄ (aerosol) in the atmosphere, NH₃ was scavenged at the growing stage, and SO₂ was also scavenged after the mature stage. NO₃ ^? in this fog event was mainly absorbed as HNO₃.     

Elemental concentrations in fresh snowfall across a regional transect in the northeastern U.S.: Apparent sources and contribution to acidity

Fresh snowfall was collected on the surface of 8 lakes across a 350 km west-east transect from northeastern New York state to the coast of Maine after a single storm. In addition, every snowfall event during the winter of 1993 was collected on a single lake near the center of the transect. Across the transect, midwestern sources appear to dominate Pb and Cd concentrations, while Sb appears to be derived from midwestern sources as well as local and/or industrial East Coast sources. In all samples, the highest Na, Cl and Mg concentrations reflect a marine influence, but at some transect sites roadspray aerosol appears to contribute to Na and Cl concentrations. The regional pattern of Ca, K, Mn and Sr concentrations and Mn/Sr ratios indicate that woodsmoke may be an important winter source of these elements at some sites. In all samples, H⁺ is strongly correlated with NO₃ ^? (R² = 0.97) and mean NO₃ ^?/SO₄ ^2? molar ratios of 6.4 for transect samples, and 4.7 for temporal samples, are higher than mean NO₃ ^?/SO₄ ^2? reported for other precipitation studies in the same region. The contribution of NO₃ ^? to the snowpack greatly exceeds that of SO₄ ^2?, and may be a major source of acidity in aquatic ecosystems during snowmelt.     

Reactive Halogen Species in the Mid-Latitude Troposphere — Recent Discoveries

While the role of reactive halogen species (e.g., Cl, Br) in the destruction of the stratospheric ozone layer is well known, up to now it was assumed that these tropospheric halogen events were confined to the polar regions during springtime. However, during the last few years, significant amounts of BrO and Cl-atoms were also found in the Arctic and Antarctic boundary layer. Recently, even higher BrO mixing ratios (up to 90 ppt) were detected by optical absorption spectroscopy (DOAS) in the Dead Sea basin during summer. In addition, evidence is accumulating that BrO (at levels around 1–2 ppt) is also occurring in the free troposphere (in polar regions as well as at mid- latitudes). In contrast to the strategosphere, where halogens are released from species which are very long lived in the troposphere, likely sources of boundary layer Br and Cl are oxidation of sea-salt halides, while precursors of free tropospheric BrO probably are short-lived organo-halogen species. In addition, it is well possible that boundary layer halogens, in particular bromine, may 'leak out' to the free troposphere and thus could have a regional or even more widespread effect. At the levels suggested by the available measurements, reactive halogen species have a profound effect on tropospheric chemistry: In the boundary layer during 'halogen events' ozone is usually completely lost within hours or days — the 'Polar Tropospheric Ozone Hole'. In the free troposphere the effective O₃- losses due to halogens could be comparable to the known photochemical O₃ destruction. Further interesting consequences include the increase of OH levels and (at low NO_X) the decrease of the HO₂/OH ratio in the free troposphere.     

Investigating the Real Air Pollution Exchange at Urban Sites Based on Time Variation of Columnar Content of the Components

As a new approach, urban air pollution was characterised by the variation of columnar content of the pollutants. Columnar content (CC) was estimated as the product of the pollutant??s mixing ratio and the mixing height. Mixing ratio data of the Metropolitan Air Quality Monitoring Network of Budapest were used, whilst mixing height was calculated by the meteorological AERMET model code. Time variation of CC refers to the real pollution exchange in the atmosphere that allows direct investigation of the emissions as well as post-emission modifications of the pollutants (such as chemical degradation or production). The diurnal urban CO cycle was found to be determined by two or three main influx peaks according to the traffic pattern of the site. The diurnal variation of NO _x level was found to be driven by traffic emission as well. Variant ratios of NO _x to CO influxes obtained for the different locations of the city range from 0.12 to 0.23, probably according to the vehicle composition of the traffic. The daily balance of photochemical production, chemical degradation and deposition of ozone yielded negative or positive depending on the location. Negative balances imply that the polluted urban atmosphere is a net ozone neutraliser source. Entrainment from the free troposphere yielded the major contributor to the diurnal ozone level at each site. The diurnal urban PM₁₀ cycle was found to be determined by traffic emission during the morning and evening rush hours whilst secondary aerosol formation around noon. In the evening, high PM₁₀ level rise was observed due to direct traffic emission as well as rapid conversion of the fine aerosol fraction to the coarse fraction.     

Measurement of acid precipitation in Norway

Since January 1972, chemical analysis of daily precipitation samples from about 20 background stations in Norway has been carried out on a routine basis. Air monitoring is carried out at six stations. The chemical analysis program is: sulphate, pH and acidity in precipitation, sulphates and SO₂ in air. In addition, more detailed chemical analysis of aerosol and precipitation has been carried out at selected stations. Some results for the measurement period 1972 to 1974 are presented. Comparison of air and precipitation concentrations of S compounds show that the precipitation scavenging efficiency is very high under the conditions in southern Norway.     

Temporal and Elevation-Related Variability in Precipitation Chemistry from 1993 to 2002, Eastern Erzgebirge, Germany

The Erzgebirge, part of the so-called former “Black Triangle”, used to represent the strongest regional air pollution of Central Europe. To test the hypothesis of deposition enhancement with height, an altitudinal gradient along a N-S transect from the Elbe river lowlands to the Erzgebirge summit was chosen to investigate chemical composition, elevation-related variability, temporal changes, and seasonal patterns of ion concentrations from 1993 to 2002. The following questions were to be answered: (1) Which role does orography play on the composition of precipitation?, (2) Does fog occurrence overrule the orographic influence?, (3) Are there changes in the past 10 years, and if so, why?, (4) Do relevant seasonal changes occur and why? Air streams from westerly and to a lesser degree south-easterly directions prevail. The average precipitation was ion-poor (23 μS cm^?1 and acidic (pH 4.5). Sulphate still was the dominant anion (52.3–59.9 μeq L^?1, while NH⁺ ₄ determined the cations (41.9–62.2 μeq L^?1. Ion concentrations decreased with altitude to about 735 m a.s.l. and subsequently increased. The seeder-feeder effect largely explains the chemical composition of precipitation; enhanced in winter through snow crystals. Sub-cloud scavenging does not explain the observed patterns. Fog occurrence enhanced the observed effects at higher altitudes. Deposition amounts doubled from the lowlands to the Erzgebirge summit. From 1993 to 2002, acidity decreased by about 50%, mainly due to reduced SO₂ -emissions.     

Aerosol and precipitation chemistry relationships at big bend national park

Aerosol chemistry, precipitation and visibility parameters are currently being measured at Big Bend National Park in Texas. This is part of a large-scale air resource evaluation program which the National Park Service is sponsoring in several southwestern national parks and monuments to determine the potential impact of local and distant pollutant sources on the environmental quality within these areas. Analysis of aerosol samples collected at six sites in the Southwest indicates that soil-derived components, organic materials and the acid-base ions of sulfate, nitrate, and ammonium are the major constituents of suspended airborne particulate matter in the remote areas of the arid region. Comparison of particulate matter chemistry and precipitation chemistry data at Big Bend National Park shows consistent features which indicate that the airborne alkaline soil material and NH₃ largely neutralize the atmospheric acidic species of H₂SO₄ and HNO₃. Given the similarity of the particulate matter composition and loading at the other monitoring sites, it is suggested that the trace chemical composition of precipitation will be similar in many remote regions of the Southwest.     

Sea Ice Approach and Chemical Species in Precipitation at Abashiri, Japan

Abashiri is a rural city on Hokkaido Island, Japan. It lies directly to the south of the Okhotsk Sea, which is the lowest latitude sea to freeze. We collected daily deposition samples over two periods: from Jan. 1997 to Mar. 1998, and from Nov. 1998 to Mar. 1999. The average concentrations of anthropogenic chemical species (NO₃ ^?, non-seasalt(nss)-SO₄ ^2?) were relatively low and those of seasalt species (Na⁺, Cl^?, Mg²⁺) were high in Japanese precipitation samples. During the period of study, we found that, when sea ice forms and approaches the coast, concentrations of seasalt species become lower, while almost no changes are found in the anthropogenic chemical species.     

Concentration and Sources of PM10 and its Constituents in Alsasua, Spain

Ambient concentrations of PM₁₀ were measured every fifteen minutes from November 2002 to October 2003 at Alsasua (Northern Spain) using a laser particle counter. A high volume sampler was also used to collect 24-h integrated PM₁₀ samples at a frequency of three running days per week (i.e. three consecutive PM₁₀ samples followed by five days without sampling) for gravimetric determination of PM₁₀ mass concentrations followed by chemical analysis of its chemical components. The annual mean PM₁₀ concentration obtained using the laser particle counter with gravimetric correction was 22.7 μg m^?3 (365 days), while the mean for the gravimetric samples was 29.5 μg m^?3 (134 days). A total of 94 integrated PM₁₀ samples were analyzed for 60 chemical species using a combination of inductively coupled plasma spectrometry (ICP) and ion chromatography (IC). The concentrations of the main PM₁₀ components were found to be generally in agreement with the values reported for other Spanish cities. Bilinear Positive Matrix Factorization (PMF2) was used to study the sources of PM₁₀ and its constituents. Six main sources of PM₁₀ were identified (average contribution to total PM₁₀ mass in parentheses): crustal material (35%), secondary sulfate (21%), secondary nitrate (14%), motor vehicles (12%), sea-salt aerosol (12%) and metallurgical industries (3%).     

Nutrient content of precipitation over Iowa

Nutrient content and pH of precipitation samples collected at six sites during 1971–1973 were studied to determine the fraction of rainfall and snowmelt and the amounts of N, S, and P added by precipitation over Iowa The amount of NH₄-N ha^?1 added by precipitation annually at each site was about equal to that added as N0₃-N. The amounts of inorganic N ha^?1 yr^?1 added ranged from 10 kg in north-central to 14 kg in west-central Iowa, and the annual amounts of S0₄-S ha^?1 added ranged from 13 kg in northeastern to 17 kg in north-central Iowa. It is estimated that, on average, precipitation adds about 0.6 kg of NH₄-N, 0.6 kg of N0₃-N, and 1.5 kg of S0₄ -S ha^?1 monthly in Iowa. However, the data indicated that, on an annual basis, the contribution of precipitation to P in soil is very small; at the most, about 0.1 kg of water-soluble P0₄-P ha^?1 was added annually in Iowa. No N0₂-N could be detected in any of the precipitation samples analyzed. Average pH value of the rainfall and snowmelt samples collected at each site during each year was about 6, individual samples seldom reached as low as pH 4. The data indicate that the concentration of S0₄-S in precipitation in this region is seasonal, high during fall and winter and low during spring and summer.     

Aerosol and cloudwater properties at whiteface mountain,New York

A field program for the measurement of the physical and chemical properties of aerosols and clouds was conducted at Whiteface Mountain, N.Y., during an 8-week period in June, July, and August 1983. Analysis of two-stage Nuclepore filter samples by proton-induced X-ray emission (PIXE) spectroscopy showed that most (85 to 90%) of the aerosol sulfate was in the accumulation mode (modal radius r - 0.1 μm) and that ?90% of total sulfate originated southwest of the Whiteface Mountain site. During a typical pollution episode originating in the Midwest, the total aerosol sulfate concentration was 19 pg m ^?3, or 63 of total dry aerosol, which was - 30 gg m^? s. Scavenging of sulfate aerosol by clouds was found to be greater than 95% efficient in clouds of 0.5gm^?3 liquid water content. Measured pH values when the air mass trajectories were from the southwest were systematically lower than when the trajectories were from the northwest or northeast, i.e., 3.4 vs 4.4 and 4.8. In the southwest sector water samples, S0₄ ^?2 and N0₃ ^? were highly correlated to each other and to free H⁺, Ca₂ ^?, Cl^?, Pb, and Ba.     

Stoichiometry of rain across the U.S.A.: Evidence of independent neutralization of sulfate and nitrate acidities

Annual wet-deposition fluxes of ions in the rains for 1982–1984 at the NADP/NTN sites across the U.S.A. were corrected for contributions from sea salt and anomalous rains (∫cations/∫ anions ratios outside 0.85 to 1.15). The resulting fluxes of normal rains in gram equivalents/ha/yr were used to determine the flux ratios of (NH₄ ⁺ + H⁺)/SO₄ ^2? and (Ca²⁺ + Mgt+ + K+ + Na+)/N03 . The first ratio is 1 ± 0.15 over a large area including most sites west of the Mississippi River, except California. A smaller core of this area has the second ratio equal to 1 ± 0.15. These results are attributed to mineral carbonate aerosol from the Western Plains being distributed by the prevailing westerly winds. This aerosol acts as a sink for NO_x and forms mineral nitrates. When the supply of carbonate is limited, free HN0₃ occurs. The aerosol NH₄HSO₄ is the main sink for NH₃ and SO₂. Thus, a major conclusion is that sulfate and nitrate acidities are neutralized independently.     

Recent Atmospheric Deposition and its Effects on Sandstone Cliffs in Bohemian Switzerland National Park, Czech Republic

The protected area ??Bohemian Switzerland National Park?? with its characteristic sandstone landscape was influenced by the long-term air pollution and acidic deposition within the area known as Black Triangle (located where Germany, Poland, and the Czech Republic meet, is one of the Europe??s most polluted areas). The local Upper Cretaceous sandstone is subhorizontally stratified, fine- to coarse-grained, quartz dominated, with low content of clay minerals. One of the significant negative effects of the intensive acidic deposition on sandstone outcrops has been identified as chemical (salt) weathering, i.e., a process when the porous sandstone rock is except of chemical influence attacked also by force of crystallization of growing salts crystals. Anions NO ₃ ^? together with SO ₄ ^2? and cation NH ₄ ⁺ were the most abundant solutes in bulk precipitation samples. Current (2002 to 2009) bulk deposition fluxes of SO ₄ ^2? determined at three sites directly in the National Park indicate decline from 23 to 16 kg^?1 ha^?1 year^?1. Infiltration of bulk precipitation solutes into the sandstone mediates the weathering processes. Natural outflow of sandstone pore-water (sandstone percolates) can be sampled only during certain days of year when the sandstone becomes saturated with water and percolates drip out on small number of sites from roofs of overhangs. Under usual conditions percolation water evaporates at the sandstone surface producing salt efflorescences??the typical example is Prav?ická brána Arch locality. The average pH of the dripping sandstone percolates was 3.76. Concentration of SO ₄ ^2? and Al in sandstone percolates reached up to 46 and 10 mg L^?1. The concentration of Al in percolates has been 160-fold greater the one in the precipitation samples suggesting the sandstone as a source. The water O and H isotopic composition of percolates has been virtually identical to precipitation samples, indicating thus relatively short residence time of the solutions within the sandstone pore-spaces. Evaporation experiments with bulk precipitation and percolate samples proved possible origin of some Ca in bulk precipitation and the sandstone rock as the source of Al and possibly of K for the salt efflorescence identified on Rock Arch body.     

A characterization of the detroit wintertime aerosol

The physical characterization of winter-time aerosol in the Detroit area studied over a 7-week period (January–March, 1983) is presented. Total suspended particle levels (<15 μm) were 56 ± 29 μg m^?3, with 66% of the material in the fine (<2.5 μm) particle fraction. Coarse and fine particle masses were reasonably correlated, indicating that local sources, not long-range transport, influenced winter-time aerosol at the site. Mobile sources were responsible for a marked diurnal variation in the nuclei mode particle count and accounted for about 10% of the submicron aerosol mass. Decreases in submicron aerosol concentrations during precipitation appear to be associated with advection of clean air into the area during frontal passage rather than to precipitation scavenging.     

Chemical Characteristics of Fog Water at Mt. Tateyama, Near the Coast of the Japan Sea in Central Japan

Measurements of the chemical composition of fog water at Murododaira (altitude, 2,450 m), on the western slope of Mt. Tateyama near the coast of the Japan Sea, were performed each autumn from 2004 through 2007. Strong acidic fogs (pH?<?4) containing high concentrations of nssSO ₄ ^2? were frequently observed in the autumn of 2005, when the air mass at Mt. Tateyama originated mainly from the polluted regions of Asia. The ratio of NO ₃ ^? /nssSO ₄ ^2? in fog water was relatively high in 2004 and 2007. High concentrations of nssCa²⁺ derived from dust particles were detected in 2006. Background Kosa particles might have been predominant in the free troposphere and could have neutralized acidic fogs in the autumn of 2006. High concentrations of sea-salt components were also observed in October 2005. The sea-salt particles might have been transported from the Pacific Ocean by a strong typhoon, and significant Mg²⁺ loss was observed. Peroxides higher than 100 μM, which are seriously harmful to vegetation were sometimes detected.     

The composition of precipitation at Snoqualmie Pass and Stevens Pass in the Central Cascades of Washington state

Bulk precipitation samples were collected weekly during the winters of 1984 and 1985 at two high elevation sites in the Washington Cascades. The Puget basin, west and upwind of the Cascade sites, includes an urban industrialized region with a variety of area and point sources of acidic oxides. The precipitation was found to be low in contaminant content with SO₄ ⁼ and NO₃ ^? concentrations as low or lower than those reported for remote pristine stations in the US or elsewhere. It is suggested that the reduced contaminant levels result from an interplay of the meteorological and washout factors unique to the region.     

A Study on Rain Acidification Processes in Ten Cities of China

A physico-chemical sub-cloud rain acidification model is used to simulate the acidification processes of rainwater in ten cities of China, based on the observation data of the chemical components of cloud- and rainwater and the concentrations of gaseous and aerosol species. The results show that there are in-cloud process and below-cloud process in the formation of acid rain, but the relative importance of these two processes is different in various cities. The acidification of rainwater under cloud is very important in Guiyang, Shanghai, Jilin, Beijing, Changsha and Chongqing, and the in-cloud and below-cloud process contribute equally to the acidification in Guilin, however, the acidification of rainwater in cloud is more important in Nanchang and Guangzhou. Overall, the aerosol has an alkalization effect on the rain, about 11%–25% of H⁺ concentration in the rainwater is neutralized over Southern China and 60%–70% is neutralied over Northern China by aerosol species. The effect of atmospheric SO₂ on acidification of rainwater is nonlinear and is different in various regions. The effects of the variation of atmospheric NH₃, H₂O₂ and aerosol species on pH of rainwater are also discussed in detail.     

A method for the analysis of the δ18O of inorganic phosphate extracted from soils with HCl

The oxygen isotope composition of phosphate (δ¹⁸O‐PO₄) has successfully been used to study the biological cycling of phosphorus (P) in seawater and marine sediments. However, only a few studies have used this approach in soils. In order to analyse δ¹⁸O‐PO₄, phosphate must be extracted from the soil, purified and converted to silver phosphate (Ag₃PO₄). The published extraction methods, successfully applied to marine waters and sediments, lead to the precipitation of impure Ag₃PO₄when used with soils or organic‐rich samples. Here we present an improved purification protocol, designed for soils and other organic‐rich samples. After extraction with HCl, phosphate is purified with multiple mineral precipitations that do not require extreme pH adjustments of the solutions. We show that contaminant‐free Ag₃PO₄ can be produced from fertilizers and various soils with different chemical and physical characteristics. Our first isotopic results confirm that differences in P status and availability in soils are expressed in the δ¹⁸O‐PO₄ signal, indicating the potential of this isotopic tracer to understand P dynamics in soil systems.