Chemical Composition Of Precipitation Research Articles

Assessing the acidification risk in the Lake Baikal region

Data from 3-year-long observations on the chemical composition of precipitation, atmospheric gases, aerosols, soils, and surface waters at three monitoring stations in the Baikal region are presented. The stability of terrestrial ecosystems and surface waters to acidification has been estimated quantitatively. It has been shown that, unlike soils, surface waters of the Baikal watershed are more sensitive to acid deposition. The permissible acidity load for soils and surface waters of the territory varied from 0.30 to 20.00 keq ha−1 yr−1, whereas the maximal contemporary acidity load attains 0.50 keq ha−1 yr−1.

Sulphur atmospheric deposition in areas with different anthropogenic loads in Belarus

This article presents some results of an investigation of sulphur atmospheric deposition in areas with different anthropogenic loads in Belarus. Through sampling and chemical analysis of precipitation, new data about sulphate concentrations in precipitation and atmospheric deposition of sulphur in different conditions, including regional background conditions, a large industrial city and a zone affected by point source of sulphur emission, were obtained. Comparison of the chemical composition of precipitation at three sampling locations has shown that the local emission of sulphur compounds has a minor influence on local sulphur deposition. This data points to the dominant role of transboundary transfer of sulphur in contamination and acidification of the environment in Belarus.

Recharge mechanism and hydrochemistry evaluation of groundwater in the Nuaimeh area, Jordan, using environmental isotope techniques

The relationship between the stable isotopic and chemical composition of precipitation and groundwater was studied in the Nuaimeh area of the Ajloun Highlands in Jordan. The isotopic composition values of precipitation and groundwater are almost identical. The spatial variation of stable isotopes in precipitation is mainly due to the effect of seasonal temperature, altitude and amount. The groundwater reveals identical variation in isotopic composition to the precipitation due to direct recharge and the karstic nature of the outcropping Turonian aquifer. Tritium levels in wells are high and their content is similar to the weighted mean value of tritium content in precipitation, indicating local recharge and low residence time. The 14C activity in the tritiated groundwater is found to be about half of the 14C activity of precipitation in the region. A geochemical evolution through dissolution of carbonate by water–carbonate rock interactions reduced the atmospheric 14C activity from 114 to 61 pmc in the groundwater. A 14C of around 61 pmc and 7.6 TU values are considered the initial concentration for the recharge in the shallow carbonate aquifer in the Yarmouk Basin. The large fluctuation of water level in observation wells during the rainy season indicates the sensitivity and direct response of the aquifer to the recharge. The chemical composition of the groundwater (Ca2+–HCO3−) gives emphasis to the short duration of water–rock interaction and indicates dissolution of the carbonate aquifer. The elevated concentrations of Cl− and NO3− in groundwater are attributed to anthropogenic sources.

Chemical composition of precipitation during 1984–2002 at Pune, India

Since 1984, bulk precipitation samples have been collected at Pune, a tropical urban location in India, in the monsoon season. Data from these studies are used to analyze the long-term trends in the major chemical constituents of precipitation. Significantly increasing trends were observed for SO4 and NO3 which could be attributed to the rise in industrial and vehicular activities during this period. Also Ca, the chief neutralizing constituent, showed decreasing trend, mainly due to the rapid urbanization that reduced the availability of open land which is the major source for Ca. This has resulted in the overall decrease in trend of pH. However, the average pH value is still in the alkaline range due to the dominance of neutralizing potential of precipitation over the acidic potential.

Precipitation Chemistry in Semi-Arid Areas of Southern Africa: A Case Study of a Rural and an Industrial Site

Experimental data on the precipitation chemistry in the semi-arid savanna of South Africa is presented in this paper. A total of 901 rainwater samples were collected with automatic wet-only samplers at a rural site, Louis Trichardt, and at an industrial site, Amersfoort, from July 1986 to June 1999. The chemical composition of precipitation was analysed for seven inorganic and two organic ions, using ion chromatography. The most abundant ion was SO4 2 − and a large proportion of theprecipitation is acidic, with 98% of samples at Amersfoort and 94% at LouisTrichardt having a pH below 5.6 (average pH of 4.4 and 4.9, respectively). This acidity results from a mixture of mineral and organic acids, with mineral acids being the primary contributors to the precipitation acidity in Amersfoort, while at Louis Trichardt, organic and mineral acids contribute equal amounts of acidity. It was found that the composition of rainwater is controlled by five sources: marine, terrigenous, nitrogenous, biomass burning and anthropogenic sources. The relative contributions of these sources at the two sites were calculated. Anthropogenic sources dominate at Amersfoort and biomass burning at Louis Trichardt. Most ions exhibit a seasonal pattern at Louis Trichardt, with the highest concentrations occurring during the austral spring as a result of agricultural activities and biomass combustion, while at Amersfoort it is less pronounced due to the dominance of relatively constant industrial emissions. The results are compared to observations from other African regions.

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/NOx 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.

The Chemical Composition of Precipitation in Madrid

The present study examines the chemical characteristics of first-fraction precipitation samples collected over a period of one year in Madrid, and patterns of temporal and spatial variation observed in their composition. One hundred and sixty-four samples of wet precipitation collected on an event basis were analysed for anions, cations, pH and electrical conductivity. Precipitation in Madrid was neutral, with only 3% of samples showing pH < 5.6. Dominant ions were calcium and sulphates. Calcium was the principal neutralizing agent, explaining 64% of all nitrates and sulphates. The marine influence did not appear to be relevant, while the soil seemed to play an important role in the composition of precipitation. Precipitation chemistry displayed seasonal differences, with higher concentrations of sulphates and chloride in autumn and winter and of calcium and sodium in the summer. There was an inverse relationship between concentrations and sample volumes; while the correlation between concentrations and the time elapsed since the last rain event was positive, though poor for normalized concentrations. Four variables (sample volume, days elapsed since the last rain event, maximum wind gust direction and season) explained to a large extent (more than 90% for some sampling stations) the variability of certain chemical variables.

Annual and seasonal trends in chemical composition of precipitation in Japan during 1989–1998

Annual and seasonal trends were discussed for precipitation chemistry in Japan on the basis of a nationwide monitoring network by Japan Environment Agency. For this analysis, 17 sites, selected from the 23 network sites after evaluation of data completeness for the present purpose, were grouped into four areas in terms of the sea which could characterize each area: the Pacific Ocean, the Japan Sea, the Seto Inland Sea and the East China Sea areas. Major ion concentrations at each site were subjected to least-squares multiple regression analysis, and discussion was principally focused on the area-groups. Each area showed significant ( p<0.05) decreasing trends in non-sea-salt sulfate (nss-SO 4 2−) concentrations with the annual mean change rate of −3.0% yr −1, whereas no significant trends were detected for NO 3 − at 59% of the sites. Ammonium (NH 4 +) showed significant increasing trends for 35%, and decreasing trends for 18% of the sites; and, the maximum change rate of 3.8% yr −1 was recorded in the Pacific Ocean area. Non-sea-salt calcium (nss-Ca 2+) concentrations significantly decreased in northern and some industrialized areas. Both the annual cycle-amplitudes and effects of precipitation amounts were significant for the four ions at almost all sites. The maximum concentrations of nss-SO 4 2− and -Ca 2+ occurred from winter to spring at most sites. The seasons when the maximum concentrations of NO 3 − and NH 4 + occurred, were found to differ from area to area. Furthermore, the trends in precipitation nss-SO 4 2−, and NO 3 − were qualitatively consistent with those of anthropogenic emissions of SO 2, and NO x in Japan, respectively.

Ionic composition of precipitation at the Central Anatolia (Turkey)

Concentrations of major ions, SO 4 2−, NO 3 −, Cl −, H +, Ca 2+, K +, Mg 2+, Ca 2+ and conductivity were measured in approximately 300 daily, wet-only rain samples collected at a permanent rural station between 1993 and 1998. Concentrations of anthropogenic ions NH 4 +, SO 4 2− and NO 3 − were among the highest values reported in whole EMEP network, suggesting that the Anatolian plateau is under strong influence of distant emission sources. Although transport of pollutants have significant influence on the chemical composition of precipitation, average pH of the rainwater is 6.2 due to extensive neutralization of acidity. Approximately 95% of the acidity in collected samples is neutralized, particularly in summer season. The neutralizing agents are primarily CaCO 3 and NH 3. Concentrations of crustal ions are higher in summer season due to enhanced resuspension of soil particles from dry surface soil. Concentrations of anthropogenic ions SO 4 2− and NO 3 − do not change significantly between summer and winter due to higher intensity of rains in summer season. Although concentrations of ions measured in this study is among the highest reported in EMEP network, wet deposition fluxes are low compared to flux values reported for similar sites in Europe, due to low annual precipitation in the Anatolia. Wet deposition fluxes of all measured parameters are highly episodic. Source regions affecting chemical composition precipitation in the Central Anatolia is investigated using trajectory statistics.

Chemistry and mineralogy of high-temperature gas discharges from Colima volcano, Mexico. Implications for magmatic gas–atmosphere interaction

Gases, condensates and silica tube precipitates were collected from 400°C (Z2) and 800°C (Z3) fumaroles at Colima volcano, Mexico, in 1996–1998. Volcanic gases at Colima were very oxidized and contain up to 98% air due to mixing with air inside the dome interior, close to the hot magmatic body. An alkaline trap method was used to collect gas samples, therefore only acidic species were analysed. Colima volcanic gases are water-rich (95–98mol%) and have typical S/C/Cl/F ratios for a subduction type volcano. δD-values for the high-temperature Z3 fumarolic vapour vary from −26 to −57‰. A negative δD–Cl correlation for the Z3 high-temperature fumarole may result from magma degassing: enrichment in D and decrease in the Cl concentration in condensates are likely a consequence of input of “fresh” batches of magma and an increasing of volcanic activity, respectively.The trace element composition of Colima condensates generally does not differ from that of other volcanoes (e.g. Merapi, Kudryavy) except for some enrichment in V, Cu and Zn. Variations in chemical composition of precipitates along the silica tube from the high-temperature fumarole (Colima 1, fumarole Z3), in contrast to other volcanoes, are characterized by high concentrations of Ca and V, low concentration of Mo and a lack of Cd. Mineralogy of precipitates differs significantly from that described for silica tube experiments at other volcanoes with reduced volcanic gas. Thermochemical modelling was used to explain why very oxidized gas at Colima does not precipitate halite, sylvite, and Mo- and Cd-minerals, but does precipitate V-minerals and native gold, which have not been observed before in mineral precipitates from reduced volcanic gases.

Influence of air mass trajectories on the chemical composition of precipitation in India

Chemical composition of precipitation was measured with wet-only samplers at a rural site at Bhubaneswar in eastern India during 1997–1998. All rain events were compared with trajectories and precipitation fields from the ECMWF. The pH and ionic concentrations were found to vary systematically with the origin of air and the amount of rainfall along the trajectory. A seasonal cycle for pH was found with a monthly median pH below 5.0 during October–December. The highest monthly median concentration of Ca 2+ was found in May with 20 μmol l −1 and for SO 4 2− in January with 52 μmol l −1. Samples with trajectories within 400 km from Bhubaneswar during the last 5 days were found to have a median pH slightly below 5.0 as an average. These samples also had the highest concentration for all measured ions, indicating large pollution sources within the region. Samples with continental origin showed a decrease of ∼70% in concentration if there had been rain during >50% of the last 5 days compared to rain during <50% of the last 5 days. High concentrations of Na + and Cl − were also found in continental samples. Resuspension of previously deposited sea salt is believed to be the reason. The data were compared with data from three other sites in western India and higher concentrations of almost all ions (NH 4 + being the exception) compared to Bhubaneswar were found at the west coast in monsoon samples.

Rapid Time Variations in Chemical Composition of Precipitation in South Korea

Data from a monitoring program on precipitation at four sites in South Korea during the period from 1993 to 1998 were analyzed for determining a time trend relationship in chemical composition of precipitation. The concentrations of nss-sulphate, ammonium and calcium were found to have decreased over time at a statistically significant level in Seoul (p<0.05). The concentration of nss-sulphate had declined by a rate of 12% per year for the period from 1993 to 1998. The concentrations of ammonium and calcium decreased by 11% and 12% per year respectively for the same period. The concurrent reduction of cation offsets the change in strong acid anion, thus the annual mean pH of precipitation has been approximately constant. In contrast to the rapid change of sulphate, the second most abundant anion, nitrate, showed no statistically significant decrease. As a result, the nitrate to nss-sulphate ratio (N/S ratio) has increased rapidly; the N/S ratio in precipitation has increased from less than 0.1 in 1985 to nearly 0.5 in 1998 at Seoul. In spite of the short monitoring period, a significant upward trend in the N/S ratio was also observed at all of the other sites suggesting that the nitrogen species contribute more to precipitation acidity throughout Korea.

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-SO42−, concentrations did not change over the past 10 years. The ratio of NO3−/nss-SO42− in precipitation significantly increased, the ratio of NO3−/NH4+ showed no marked fluctuations, and the ratio of [nss-Ca2++NH4+]/[nss-SO42−+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.

Chemical Composition of Precipitation in Beijing Area, Northern China

Variations of anions (SO42-, NO3-,NO2-, Cl- and F-),cations (K+,Na+, Ca2+, Mg2+ and \({NH}_4^+\)+) and pH values in precipitation, througfall and stemflow samples collected overa four-year period (1995–1998) in Beijing (two sitesZhongguancun and Mangshan) are presented. The annualvolume-weighted range of pH values were 6.57–7.11 inprecipitation, 5.46–6.86 in thoughfall and 5.32–6.41 instemflow. The fominant anion was \({SO}_4^{2-}\), while Ca+and NH4+ were the main cations in precipitation,throughfall and stemflow. Most of ion concentrations with precipitation, throughfall and stemflow volume showed negative correlation, except for some ones. Significant correlationvalues were also found between ions (SO42-,NO3-, Cl-, F-, Ca2+,Mg2+ andNa+) in precipitation, throughfall and stemflow indicatedthe common sources of these ions such as coal combustion,automobile emission and fertilizers application. Compared toprecipitation, there was an increased ion concentration inthroughfall or in stemflow. Changes of ion concentrations werein Quercus liatungensis Koiz. and Pinus tabulaefornisCarr. throughfall (or stemflow) because of different crown andbark qualities of tree species.

Chemical composition of precipitation in a Mexican Maya region

The chemical characteristics of wet precipitation in Puerto Morelos, Quintana Roo State, Mexico, were measured from April 1994 to December 1995. Puerto Morelos is located in the Caribbean Mayan coastal region of the Peninsula of Yucatan, and is normally exposed to winds from the Caribbean region. Wetfall was analyzed for pH, conductivity and Cl −, NO 3 −, SO 4 2−, Na +, NH 4 +, K +, Mg 2+ and Ca 2+ ion concentrations. Volume–weighted mean pH for the whole sampling period was 5.35, although values as low as 4.6 were measured in several rain samples. Concentrations of all species correlated negatively with rain volume. Sea-salt aerosols contributed with most of the Na +, Cl −, Mg 2+, K + and SO 4 2− found in wet precipitation. The mean [SO 4 2− excess] was 9.7 μEq l −1, which agrees with the background hemispheric values of ≈10 μEq l −1 reported elsewhere. The mean [NO 3 −] was 11.4 μEq l −1, almost four times higher than the background hemispheric value of ≈2.5 μEq l −1 reported elsewhere. However, a major component causing the slight acidity character of rain in Puerto Morelos seems to be H 2SO 4.

Chemical composition of precipitation and wet deposition of major ions on the Korean peninsula

Daily wet precipitations were collected at nine stations in South Korea from May 1996 to April 1998 and analyzed for pH, electrical conductivity and major ions; SO 4 2−, NO 3 −, Cl −, NH 4 +, Ca 2+, Na +, Mg 2+ and K +. The volume-weighted mean concentrations of NO 3 − and non-seasalt SO 4 2− were 19.3 and 43.0 μeq l −1, respectively, which were comparable to Northeast America and Central Europe. However, the level of H + was found to be significantly lower as a result of neutralization by ammonia and calcium containing compounds. Although the pH of individual precipitations fluctuated excessively with a wide range from 3.4 to 8.0, the annual mean value ranged from 4.6 to 4.8 without area variation. With the exception of the seasalt ions, no distinct spacial variations in ion composition were observed. On the other hand, seasonal variations were evident. Annual wet deposition was estimated and compared to that in East Asian countries and other continents.

Precipitation chemistry in East Asia

The chemical composition of precipitation in East Asia was analyzed on the basis of the results of cooperative monitoring performed during the period from 1992 to 1993. The wet deposition of soluble ions was characterized by two major factors; the geographical distribution of precursor production through natural and anthropogenic activities, and the meteorological conditions such as wind system and rainfall pattern due to the Asian monsoon. Although northeastern China had the largest anthropogenic emission source, precipitation with relatively high pH value was observed. At islands in the northern Pacific far from major anthropogenic emission sources, precipitation with relatively low pH value was observed. It was suggested that ammonia and calcium were constantly produced in the continent, and that the higher concentrations of these bases in the atmosphere were incorporated into precipitation elements and neutralized the acidity due to H 2SO 4 and HNO 3 from fossil fuel combustion. The ratio of [nssCa 2++NH 4 +]/[nssSO 4 2−+NO 3 −] in precipitation was highest on the continent, moderate in the Korean Peninsula and the Japanese Islands, and lowest in the northern Pacific; in other words, this ratio decreased as the distance from the continent increased. In the central region of East Asia, which is affected by both continental cold, dry air masses and subtropical warm, humid air masses, the frequency distribution of pH of precipitation showed a bimodal pattern in which unimodal patterns of northern China and that of the Japanese Islands were superimposed. The wet deposition of nssSO 4 2−, NO 3 −, nssCa 2+, and NH 4 + showed relatively small differences between the sites, while that of Na + and Cl −, relatively large differences between the sites, reflecting the field of ionic concentration and amount of precipitation in East Asia.

Seasonal variations in the geochemistry of shallow groundwater hosted in granitic till

The groundwater chemistry in a small catchment in northern Sweden has been studied for a period of 15 months, including two snowmelt events. The groundwater was sampled from two wells in a slope facing a small stream. One well was placed at the top of the slope (28 m from the stream), and the other was placed closer to the stream (13 m from the stream). Both wells were completed to approximately the same elevation (1.5 m below the stream bed). In addition to groundwater compositions, the chemical composition of precipitation, soil water and stream water was investigated. The chemical composition of the groundwater in the well farther from the stream was fairly constant during the studied period. In the closer well the concentrations of Ca, Mg, Na, Sr, Si, and alkalinity decreased by approximately 10% during snowmelt in May. In contrast, the concentrations of Fe, Al, Ce and Cu increased. After the snowmelt, during June and July, the concentrations of Ca, Mg, Na, Sr, Si, and alkalinity in the closer well increased by a factor of 2–5 compared with the concentrations prior to the snowmelt. By August, the concentrations had decreased to the same levels as before the snowmelt and remained constant until next snowmelt. To explain these variations the Ca/Sr ratio was used as a natural chemical tracer for different water masses. It was found that the increased concentrations of Ca, Mg, Na, Sr, Si, and alkalinity during summer was caused by changes in the groundwater flow direction, which resulted in upwelling of deeper groundwater. At this time the area at the closer well acted as an unsaturated discharge area. The concentrations of Fe, Al, Ce and Cu decreased rapidly after the snowmelt and then remained constant except for two peaks in July and August. These variations were due to mixing with rapidly percolating soil water from the E-horizon and melt water or rain water, which is supported by increased content of dissolved oxygen.

Source identification and variation in the chemical composition of precipitation at two rural sites in France

A receptor-oriented model is developed to identify and locate the sources of the constituents present in precipitation collected at two rural French stations, namely Donon and Morvan. Firstly, factor analysis is applied to the chemical data sets. Three factors are identified reproducing the concentrations observed in precipitation. These factors represent the acid sources (characterized by the ionic combination between H +, SO 4 2− and NO 3 −), marine sources (Na +, Cl − and Mg 2+) and crustal sources (Ca 2+ and K +). Then, the factor scores of samples are combined with the air parcel back trajectories in the same scheme of model calculation to produce the probability maps of source locations. This approach, called potential source contribution function (PSCF) analysis, locates the acid sources in the industrial areas of Northeastern Europe and Great Britain, the marine sources in the Atlantic Ocean and the crustal sources around the Mediterranean Basin. The seasonal profiles of these factors are performed and contrasted with the atmospheric processes and meteorological conditions which prevail in each season. A classification of these daily samples is also made according to four origin sectors, to examine the variations in ionic composition of precipitations from one sector to another. The results of this classification are in agreement with the source locations found by the PSCF analysis.

Chemical composition of precipitation at two sampling sites in Mexico: A 7-year study

This paper describes the results of a study of the chemical composition of bulk and wet precipitation, collected for 7 years in a large urban area and a forested rural site in Central Mexico. In rain samples from both sites, sulfate was the most abundant ion followed by ammonium. Seasonal patterns of monthly volume-weighted concentration show that the highest values of SO 2− 4 NO 3 −, Ca 2+ and NH 4 +were measured in May, the beginning of the rainy season in Central Mexico. The lowest values were observed from July to September, the months when most thunderstorms occurred. Multiple regression correlation analysis was applied to all data and a hierarchical model was used to select the variables included in the final model. In Rancho Viejo the model showed that SO 2− 4 contributed with 41% in the H + concentration prediction. In Mexico City, despite the high SO 4 2− concentration in rain water, this ion only contributed 0.46% whereas Ca 2+ contributed in wet and bulk precipitation, 61 and 41%, respectively. Finally no long-term trends were noticed.