The effect of alkaline dust decline on the precipitation chemistry in northern Japan

The precipitation chemistry in northern Japan, especially Hokkaido, has been investigated since 1982. This area has often been found to have high concentrations of alkaline road dust (asphalt dust) in the air, caused by the use of studded tires during the winter. It is well known that the composition of precipitation in these areas is often dominated by asphalt dust including calcium bicarbonate. However, recently the concentration of asphalt dust in the air has decreased owing to a ban on the use of studded tires. Simultaneously, in precipitation, the lowering of pH values and the increase of hydrogen ion depositions have been occurring owing to the decrease of non-sea-salt calcium ions (nss-Ca²⁺) concentrations and depositions derived from asphalt dust. In addition, we found that a decrease of nss-Ca²⁺ firstly leads to a decrease of bicarbonate ions (HCO₃ ^?), the counter ion to nss-Ca²⁺ in asphalt dust. Therefore, the increase of H⁺ concentrations and depositions was great in comparison with the decrease of nss-Ca²⁺ concentrations and depositions in areas where the HCO₃ ^?concentrations, varied by pH, and depositions had been low. Furthermore, this variation was mainly observed in the ionic composition of snow cover and snowfall at sites along the Japan Sea in northern Japan during winter. In this area, the Acid Shock effect may become a serious problem from the decline of pH values in melting snow. Moreover, we found that ammonium ions and non-sea-salt sulfate ions depositions have also been decreasing in response to a decrease of nss-Ca²⁺ depositions, derived from asphalt dust. It seems that this phenomenon is caused by the decrease of asphalt dust concentrations in the air.     

Long-Term Trends in the Chemical Composition of Precipitation over Western Japan

Wet deposition monitoring was conducted at six rural stations in western Japan, during the period from 1987 through 1996. Long-term trends in the concentration of non-sea salt ions were analyzed on the basis of the data obtained. The monitoring results indicated that annual average concentrations of NO₃ ^? and NH₄ ⁺ in precipitation significantly increased on the order of 45%, and that of nss-Ca²⁺ and nss-SO₄ ^2?, concentrations did not change over the past 10 years. The ratio of NO₃ ^?/nss-SO₄ ^2? in precipitation significantly increased, the ratio of NO₃ ^?/NH₄ ⁺ showed no marked fluctuations, and the ratio of [nss-Ca²⁺+NH₄ ⁺]/[nss-SO₄ ^2?+NO₃ ^?] slightly increased during the period. These findings suggested that the wet deposition of NO₃ ^? and NH₄ ⁺ in western Japan, particularly that in the winter season, was influenced by the long-range transport of nitrogen oxides and ammonia from the Asian continent.     

Characteristics in Concentration of Chemical Species in Ambient Air Based on Three-Year Monitoring by Filter Pack Method

Continuous monitoring of concentrations of particulate matter and gaseous compounds for three years by a four-stage filter-pack method clarified the characteristics in the concentrations of chemical species in particulate matter and gaseous compounds in ambient air in Kobe, Japan. The amount of materials in blank filters was low enough for this method to be used for the monitoring of ambient air. Little or none of the hydrogen chloride was derived anthropogenically. The concentrations of both particulate sulfate and sulfur dioxide in spring and summer were significantly higher than those in autumn and winter. The concentration of gaseous nitric acid was high in summer, which suggests that active photochemical reactions in the atmosphere provided more nitrogen species in summer. The measured concentration products [HNO₃][NH₃] showed good agreement with the theoretical predictions with some exceptions. The total concentration of ammonium species showed no significant seasonal variation except that the concentration in winter was low. The concentration of nss-Ca²⁺ in spring was significantly higher than that in the other seasons, which is most likely associated with the so-called yellow-sand events. The concentrations of nss-K⁺ and nss-Ca²⁺ accounted for most of K⁺ and Ca²⁺, respectively, whereas that of nss-Mg²⁺ accounted for only 5% of Mg²⁺     

Background pollution in the Arctic air mass and its relevance to North American acid rain studies

The Arctic air mass is a unique meteorological feature of the northern hemispheric atmosphere. Possessing well-defined meteorological characteristics, it occupies not only the polar region but also a large fraction of the Canadian and Eurasian land masses during the period November to April. Poor pollutant removal by precipitation and dry deposition within the air mass and a strong transport pathway between Eurasian mid-latitudinal sources and the north, result in elevated levels of acidic anthropogenic aerosols and gases in the air mass during winter. In summer, weak north/south transport and strong pollutant removal between the Arctic and mid-latitudes and within the Arctic, results in lower airborne concentrations of acidic pollutants. Due to the presence of the relatively polluted Arctic air mass, ‘background’ air concentrations of SO₄ ⁼, SO₂ and total NO₃ ^? are elevated in western Canada during winter. Typical mean monthly concentrations from December to March are 0.8 to 2.1, 1.0 to 2.4 and 0.1 ? 0.6 μg m^?3, respectively. In the absence of the neutralizing influence of alkaline soil dust, the acidity of snow forming in western Canada during winter is expected to range from 5 to 20 μeq l ^?1.     

Precipitation Composition in the Ohio River Valley: Spatial Variability and Temporal Trends

Sulfate (SO₄ ^2?), nitrate (NO₃ ^?) and ammonium (NH₄ ⁺) concentrations in precipitation as measured at NADP sites within the Ohio River Valley of the Midwestern USA between 1985 and 2002 are quantified and temporal trends attributed to changes/ variations in (i) the precipitation regime, (ii) emission patterns and (iii) air mass trajectories. The results indicate that mean SO₄ ^2? concentrations in precipitation declined by 37–43% between 1985 and 2002, while NO₃ ^? concentrations decreased by 1–32%, and NH₄ ⁺ concentrations exhibited declining concentrations at some sites and increasing concentrations at others. The change in SO₄ ^2? concentrations is in broad agreement with estimated reductions in sulfur dioxide emissions. Changes in NO₃ ^? concentrations appear to be less closely related to variations in emissions of oxides of nitrogen and exhibit a stronger dependence on weekly precipitation volume. Up to one quarter of the variability in log-transformed weekly NO₃ ^? concentrations in precipitation is explicable by variations in precipitation volume. Trends in annual average log-transformed SO₄ ^2? concentrations exhibit only a relatively small influence of variability in weekly precipitation amount but at each of the sites considered the variance explanation of annual average log-transformed SO₄ ^2? by sampling year was increased by removing the influence of precipitation volume. Annual mean log-transformed ion concentrations detrended for precipitation volume (by week) and emission changes (by year) exhibit positive correlations at all sites, indicating that the residual variability of SO₄ ^2?, NO₃ ^? and NH₄ ⁺ may have a common source which is postulated to be linked to synoptic scale variability and air mass trajectories.     

Comparison of the Chemical Composition of Precipitation on the Western and Eastern Coasts of Korea

Precipitation samples were collected at two coastal sites on the Korean Peninsula, Kangwha on the western coast and Yangyang on the eastern coast, from September 1991 to February 1997. The samples were analyzed for concentrations of major ions, in addition to pH and electrical conductivity. The annual volume-weighted mean pH values were 4.89 and 5.05 at Kangwha and Yangyang, respectively. The pH was generally lower at Kangwha than that at Yangyang, especially during the winter, because of reduced neutralizing inputs and greater acid inputs in winter. Dominant ions were different with NH₄ ⁺ and SO₄ ^2- most important at Kangwha and Na⁺ and Cl^- at Yangyang. Neglecting sea salt components, nss-SO₄ ^2- and NO₃ ^- were important anions and nss-Ca²⁺ and NH₄ ⁺ were important cations at both sites. Concentrations of these ions were 1.2–1.6 times higher at Kangwha than at Yangyang. Annual mean concentrations of these ions varied little during the study, while larger seasonal variations were observed. Annual mean nss-SO₄ ^2-/NO₃ ^- ratios at Kangwha and Yangyang were 2.8 and 2.6. The 5 yr annual mean values of nss-SO₄ ^2-/NO₃ ^- showed no trend at Kangwha but a decreasing tendency at Yangyang. The decreasing trend is similar to the decreasing trend in emissions of SO₂/NO_x in South Korea. Regional differences in chemical composition between Kangwha and Yangyang appear to be associated with long-range transport of acidic gases and alkaline dust originated from other regions.     

Geochemical Distribution of Selected Heavy Metals in Stream Sediments Affected by Tannery Activities

Bayesian regularized back-propagation neural network (BRBPNN) was developed for trend analysis, acidity and chemical composition of precipitation in North Carolina using precipitation chemistry data in NADP. This study included two BRBPNN application problems: (i) the relationship between precipitation acidity (pH) and other ions (NH₄ ⁺, NO₃ ^?, SO₄ ^2?, Ca²⁺, Mg²⁺, K⁺, Cl^? and Na⁺) was performed by BRBPNN and the achieved optimal network structure was 8-15-1. Then the relative importance index, obtained through the sum of square weights between each input neuron and the hidden layer of BRBPNN(8-15-1), indicated that the ions' contribution to the acidity declined in the order of NH₄ ⁺ > SO₄ ^2? > NO₃ ^?; and (ii) investigations were also carried out using BRBPNN with respect to temporal variation of monthly mean NH₄ ⁺, SO₄ ^2? and NO₃ ^? concentrations and their optimal architectures for the 1990–2003 data were 4-6-1, 4-6-1 and 4-4-1, respectively. All the estimated results of the optimal BRBPNNs showed that the relationship between the acidity and other ions or that between NH₄ ⁺, SO₄ ^2?, NO₃ ^? concentrations with regard to precipitation amount and time variable was obviously nonlinear, since in contrast to multiple linear regression (MLR), BRBPNN was clearly better with less error in prediction and of higher correlation coefficients. Meanwhile, results also exhibited that BRBPNN was of automated regularization parameter selection capability and may ensure the excellent fitting and robustness. Thus, this study laid the foundation for the application of BRBPNN in the analysis of acid precipitation.     

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.     

Source Identification of Rural Precipitation Chemistry in Japan

Precipitation chemistry was discussed from the viewpoint of potential sources for four rural sites where wet-only daily-basis measurement data sets were available during the period from April 1996 to March 1997 in Japan. Annual volume-weighted mean concentrations of nss-SO₄ ^2? and NO₃ ^? ranged from 18.0 to 34.6 µeq L^?1, and from 9.3 to 23.1 µeq L^?1, respectively. The degree of neutralization of input acidity in terms of the concentration ratio, [H⁺] / ([nss-SO₄ ^2?] + [NO₃ ^?]), ranged from 0.46 to 0.63. This suggests that about half of the input acidity due to H₂SO₄ and HNO₃ was neutralized by NH₄ ⁺ and nss-Ca²⁺ to produce the pH values of 4.46 to 4.82 for these sites. Maximum likelihood factor analysis was then performed on the logarithmically transformed daily wet deposition of major ions. Two factors successfully explained a total of about 80% of the variance in the data for each site. Interpreting varimax rotated factor loadings, we could identify two source types: (1) acid source with large loadings on ln(H⁺), ln(nss-SO₄ ^2?), ln(NO₃ ^?) and ln(NH₄ ⁺), (2) sea-salt source with large loadings on ln(Na⁺), ln(Cl^?), ln(Mg²⁺) and ln(K⁺). The rural wet deposition over Japan appears to have a similar structure in terms of the kinds of sources and their relative location.     

Chemical Composition of Precipitation, Throughfall and Soil Solutions at Two Forested Sites in Guangzhou, South China

Rain water at two forested sites in Guangzhou (south China) show high concentrations of SO₄ ^2?, NO₃ ^? and Ca²⁺ and display a remarkable seasonal variation, with acid rain being more important during the spring and summer than during the autumn and winter. The amount of acid rain represents about 95% of total precipitation. The sources of pollutants from which acid rain developed includes both locally derived and long-middle distance transferred atmosphere pollutants. The seasonal variation in precipitation chemistry was largely related to the increasing neutralizing capacity of base cations in rainwater in winter. Soil acidification is highlighted by high H⁺ and Al³⁺ concentrations in soil solutions. The variation in elemental concentration in soil solution was related to nitrification (H⁺, NH₄ ⁺ and NO₃ ^?) and cation exchange reaction (H⁺, Al³⁺) in soil. The negative effect of soil acidification is partly dampened by substantial deposition of base cations (Ca²⁺, Mg²⁺ and K⁺) in this area.     

The Effect of Changes in European Anthropogenic Emissions on the Concentrations of Sulphur and Nitrogen Components in Air and Precipitation in Lithuania

Sulphur (S) and nitrogen (N) components are of great concern because acidification and eutrophication still remain an important environmental issue in many regions of the world. Continuous monitoring (1981–1999) of S and N components both in air and precipitation in Lithuania (LT) has allowed us to evaluate the regional and temporal variations in relation to the pollutant emission changes. Despite of inter-site variability in concentration of pollutants within the regional scale, data showed a marked decrease in S concentrations both in air and precipitation over the Lithuania as a whole. Non-seasalt sulphate (nssSO₄ ^2?) concentrations in precipitation and air decreased from 2.06 to 0.52 mgS/l and from 3.97 to 1.07 µgS/m³, respectively. The number of acidic (pH<5) precipitation did not exceed 50 % during 1995–1999. The observed trends for S species are consistent with those for sulphur dioxide (SO₂) emission in Europe and Lithuania. Although nitrogen dioxide (NO₂) concentration in air decreased by 17 %, significant changes in nitrate (NO₃ ^?) concentrations neither in precipitation nor in air have been observed. Three-day backward air isobaric trajectories were used for the identification of the source region of air pollutants     

Regional Differences in the Relation Between Monthly Precipitation and Bulk Concentration in France (Renecofor)

Bulk precipitation was sampled weekly from 1993 to 1994 at 27 sites, covering the whole country. In this paper the relations between decreasing concentrations of 4-weekly mean weighted samples with increasing 4-weekly precipitation are studied using two types of equations: (i) y = a+b/x; (ii) y+1= ax^b, where y = concentration of an ion and x = 4-weekly precipitation quantity. Relationships were studied for the major ions. H⁺ did not show any relationship with the rainfall amount. From the 216 regressions (27 sites × 8 ions) for all the other ions, 55.6% showed a good fit (r equal or above 0.6) and 16.2% a very good fit (r equal or above 0.85). Good fits were found for 85% of the regressions for N-NO₃ ^-, 81% for S-SO₄ ^2-, 63% for Ca²⁺, 59% for K⁺, 55% for N-NH₄ ⁺, 37% for Mg²⁺, 33% for Cl^- and 29% for Na⁺. The comparison between sites for the same ions showed: (i) the ranking of the sites after the regressions from lower to higher concentration levels does not necessarily correspond to the ranking of the sites bi-annual mean weighted concentrations; (ii) sites showed similar behaviour for certain ions for which an explanation could be found, based on local or regional emission characteristics or air mass influences, and for others this was not possible; (iii) for certain ions and pairs of sites, comparable annual precipitation led to comparable behaviour, for others precipitation was not an explanatory factor at all, (iv) local and regional influences seem to have a much greater impact on decreasing concentrations than the gradient from the Atlantic coast to the eastern French border.     

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.     

Trends of Major Inorganic Species at the Small Watershed Ecosystem in Northern Tama Hills, the Western Tokyo Metropolitan Area, Japan

Acid rain impacts on the small forested watershed in northern Tama Hills in the western Tokyo metropolitan area Japan were investigated by surveying the trends of major inorganic species in rain and spring water during the years from 1991 to 1997. The ecosystem had been stressed by the annual H⁺-deposition of around 0.43 kmol/ha. The spring water outflow corresponded to ca. 27% of the precipitation. Budgets for the precipitation input and spring water output gave good balance for Cl^?,?0.01 ±0.09 kmol/ha, net gains for H⁺, NO₃ ^? and SO₄ ^2?, and to the contrary, relatively large net losses for Na⁺, Mg²⁺, Ca²⁺, Si(as H₄SiO₄) and HCO₃ ^?, thus suggesting the dissolution of chemical weathered products of silicate minerals. Further, in spring water, some concentration relationships were found: CNa⁺ = 376.5?2.05CCl^? (R²=0.748), CNa⁺=12.69+0.5556CHCO₃ ^? (R²=0.872) and CH₄SiO₄=130.0 + 1.108CHCO₃ ^? (R²=0.816). Evidently, the spring water chemistry reflected probable geochemical changes in the soil layer of the watershed. Mass balance in the ecosystem and estimation of the spring water output of chemical weathered products were investigated     

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.     

Changes in the Chemistry of Precipitation in the United States, 1981–1998

Regulatory measures in the United States, such as Title IV of the Clean Air Act Amendments of 1990, have primarily restricted sulfur dioxide emissions as a way to control acidic deposition. These restrictions, coupled with increasing concentrations of NH₄ ⁺ in wet deposition in some regions of the U.S. and continued high emissions of nitrogen oxides have generated a significant shift in the chemistry of precipitation as measured at National Atmospheric Deposition Program/National Trends Network sites. Trends in precipitation chemistry at NADP/NTN sites were evaluated for statistical significance for the period 1981–1998 using a Seasonal Mann-Kendall Test, a robust non-parametric test for detection of monotonic trends. SO₄ ^2? declines were detected at 100 of the 147 sites examined while no sites exhibited increasing SO₄ ^2? trends. On average, SO₄ ^2? declined 35% over the period 1981–1998 with downward SO₄ ^2? trends being most pronounced in the north-eastern United States. In contrast, no consistent trends in NO₃ ^? concentrations were observed in precipitation in any major region of the United States. Although the majority of sites did not exhibit significant trends in NH₄ ⁺ concentration, 30 sites exhibited upward trends. For Ca²⁺ concentration in precipitation, 64 sites exhibited a significant decreasing trend and no sites exhibited an upward trend.     

Ion elution and release sequence from deep snowpacks in the central Sierra Nevada,California

Elution of Cl^?, SO₄ ^2?, NO₃ ^?, and H⁺ often occurred in that order at a site in the central Sierra Nevada, California, that receives an annual average of 1000 cm of snowfall which is low in acidic components. During eight winter periods of above-base level snowpack outflow, and one spring melt period, on the average 25% of the ions were discharged at the following percentages of outflow volumes: Cl^? at 11%, NO₃ ^? at 13%, SO₄ ^2? at 18%, and H⁺ at 20%. Seven of eight winter outflows were associated with low ionic strength rainfall onto the snowpack. Mean solute concentrations during the first 25% and first 50% of the total outflow were significantly greater than during the last 75% and last 50% of the total outflow for Cl^?, NO₃ ^?, and SO₄ ^2?, but not for H⁺. Maximum solute concentrations were up to 2.9 times the overall event volume-weighted mean concentrations for Cl^?, 3.7 times for NO₃ ^?, 3.0 times for SO₄ ^2?, and 2.9 times for H⁺.     

Sulphur and nitrogen deposition in Norway,status and trends

The total deposition of sulphur (S) and nitrogen (N) components in Norway during the period 1988–1992 has been estimated on the basis of measurement data of air- and precipitation chemistry from the national monitoring network. There are large regional variations in depositions with highest values in the southwestern part of Norway. Time series analysis of annual mean concentrations of sulphur dioxide (SO₂) and sulphate (SO₄ ^––) in air, non marine SO₄ ^––, nitrate (NO₃ ^–) and ammonium (NH₄ ⁺) in precipitation, shows a significant reduction in the S concentrations both in air and precipitation. In precipitation the concentrations are reduced by 30–45 percent in Southern Norway and 45–55 percent in Central and Northern Norway. Even larger reductions are observed in air concentrations with 50–65 percent reduction in Southern Norway and 65–88 percent reduction further north. For N components there are generally no significant trends in concentration levels nor in precipitation or air. The observed trends are comparable with reported trends in emission.     

recent lake acidification and recovery trends in southern quebec,canada

A total of 51 lakes in southern Quebec, Canada, were sampled between 1985 and 1993 to study changes in water chemistry following reductions in SO₂ emissions (main precursor of acid precipitation). Time series analysis of precipitation chemistry revealed significant reductions in concentrations and deposition of SO₄ ^2- from 1981 to 1992 in southern Quebec as well as reductions in concentrations and deposition of base cations (Ca²⁺, Mg²⁺), NO₃ ^- and H⁺ in the western section of the study area. Reductions in atmospheric inputs of SO₄ ^2- have resulted in decreased lakewater SO₄ ^2- concentrations in the majority of the lakes in our study, although only a small fraction (9 of 37 lakes used in the temporal analysis) have improved significantly in terms of acidity status (pH, acid neutralizing capacity – ANC). The main response of the lakes to decreased SO₄ ^2- is a decrease in base cations (Ca²⁺+Mg²⁺), which was observed in 17 of 37 lakes. Seventeen lakes also showed significant increases in dissolved organic carbon (DOC) over the period of study. The resulting increases in organic acidity as well as the decrease in base cations could both play a role in delaying the recovery of our lakes.     

Changes of Some Components of Precipitation in East Germany after the Unification

A network of 15 sites of precipitation monitoring was built-up to characterize the spatial and temporal changes of pollutants over East Germany. Rain water samples were analysed and characterized regarding their acidity, conductivity, main water soluble components (Cl^-, NO₃ ^-, SO₄ ^2-, Na⁺, NH₄ ⁺, K⁺, Ca²⁺, Mg²⁺), volume and the meteorological parameters. Dependent on the changes of emission of pollutants, resulting from the reformation of industry, the decrease of stock farming, and increase of traffic (by the factor of ≈1.5) in East Germany, a drop could be observed with the sulphate and calcium concentrations in the precipitation by 20 to 50 and 30 to 70%, respectively. An increase could not be ascertained with the nitrate concentration and the acidity.