Real-time wet scavenging of major chemical constituents of aerosols and role of rain intensity in Indian region

Real-time simultaneous studies on chemical characteristics of rainwater and PM₁₀ aerosols were carried out to understand the scavenging of major chemical components in Indian region. The concentrations of Ca²⁺, NH₄⁺, SO₄²⁻ and NO₃⁻ were observed to be lower in the aerosol samples collected during rain as compared to before and after rain events. The most significant reduction was noticed for Ca²⁺ (74%) during rain which showed highest scavenging ratio (SR) and indicated that below-cloud scavenging is an effective removal process for Ca²⁺ in Indian region. Among non-sea salt components, Ca²⁺ had highest SR at Hyderabad indicating typical characteristics of crustal influence as abundance of calcium carbonate in soil dust has been reported in India. However, the levels of these major chemical components gradually got build-up in due course of time. After rain events, the levels of SO₄²⁻ aerosols were noticed to be substantially higher (more than double) within 24 h. In general, scavenging ratios for all components (except Ca²⁺, NH₄⁺ and K⁺) were higher over BOB as compared to Hyderabad. The maximum fall in aerosol levels (BR minus AR) was observed during continuous and low intensity rain events that did not allow building up of aerosol concentrations.     

Ionic composition of precipitation at the Central Anatolia (Turkey)

Concentrations of major ions, SO₄²⁻, NO₃⁻, Cl⁻, H⁺, Ca²⁺, K⁺, Mg²⁺, Ca²⁺ 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 NH₄⁺, SO₄²⁻ and NO₃⁻ 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 CaCO₃ and NH₃. Concentrations of crustal ions are higher in summer season due to enhanced resuspension of soil particles from dry surface soil. Concentrations of anthropogenic ions SO₄²⁻ and NO₃⁻ 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.     

On the Relationship between Acid Rain and Cloud Type

Abstract

Spanish European Monitoring and Evaluation Programme (EMEP) stations were selected to relate acid rain episodes with the meteorological structure that caused the rainfall during a 5-year period. A principal component analysis (PCA) was used to determine the origin of major ions (SO₄ ^2?, NO₃ ^?, Cl^?, Ca²⁺, K⁺, Mg²⁺, and Na⁺) in the rainwater. In addition, the meteorological origin of the rain was identified.

Previous works suggested a relationship between acid rain and storm convective clouds. However, statistical analyses of pH values show that only the short-lived con-vective phenomena may cause acid rain in Spain. In fact, rain generated by fronts and that related to long-lived convective systems is neutral or even slightly basic. Results suggest that the acid rain might be related to the meteorological time scale instead of to the cloud type.     

Chemical composition of rainwater in the northeastern Romania, Iasi region (2003–2006)

Chemical composition of rainwater was studied in the northeastern Romania, Iasi region, and the concentrations of major inorganic and organic ions were measured in samples collected between April 2003 and December 2006. The pH of the rainwater is 5.92 (volume weighted mean average, VWM) suggesting a sufficient load of alkaline components neutralizing its acidity. On average, 97% of the acidity in the collected samples is neutralized by CaCO₃ and NH₃. Clear seasonal variations were observed for some of the identified ions (e.g., SO₄²⁻, NO₃⁻, Ca²⁺, NH₄⁺). The data obtained during this work revealed that both concentrations and fluxes of anthropogenic source-related ions (e.g., SO₄²⁻, NO₃⁻ and NH₄⁺) are among the highest reported for European sites. It is shown that meteorology and long-range transport processes may concur to their high levels.     

Time Trends and Seasonal Variation of the Rainwater Chemical Composition in Spain

Abstract

A multiple regression model was used to describe temporal variations of the concentrations of H⁺, SO₄ ^{2 -}, NO₃ ^- and NH₄ ⁺ in Spanish rainwater. The model included the effects of linear trend, annual cycle, and precipitation quantity simultaneously.

The model fit very well for SO₄ ^{2 -} and NO₃ ^-, with statistical evidence of annual cycle and effect of precipitation quantity for these two ions and for NH₄ ⁺, but not for H⁺. There is no trend for any ion, with the single exception of a decreasing trend for H⁺ in one of the stations used.     

Chemical composition of rainwater and anthropogenic influences in the Piracicaba River Basin,Southeast Brazil

The influences of different kinds of anthropogenic activities on rainwater chemistry in a tropical area were studied during one uninterrupted year at Piracicaba River Basin (Southeast Brazil). A total of 272 rainwater samples collected continuously from August 1997 to July 1998 at four different sites were analyzed for F⁻, CH₃COO⁻, HCOO⁻, MSA, Cl⁻, NO₂⁻, Br⁻, NO₃⁻, SO₄²⁻, C₂O₄²⁻, PO₄³⁻, Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, DOC (dissolved organic carbon), DIC (dissolved inorganic carbon), pH and conductivity. The most abundant ion was H⁺ and rain acidity was significant at all sampling sites (average pH of 4.4–4.5). The sources of this free acidity differ among sites and appear to be correlated to the different land-uses. The composition of rainwater appeared to be controlled mostly by three sources: soil dust, sugar cane burning and industrial emissions.     

Water-soluble main ions in precipitation over the southeastern Adriatic region: chemical composition and long-range transport

Background, aim and scope  

Precipitation samples collected from 1995 to 2000 at meteorological station in the eastern outskirts of Herceg Novi (Montenegro) were analysed on Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^–, SO₄ ^2–, NO₃ ^– and NH₄ ⁺. Four-day backward trajectory simulations were conducted during the precipitation period to investigate the regional transport of main ions and their deposition in the region of the southeastern Adriatic Sea. The air mass trajectories were classified into six trajectory categories by the origin and direction of their approach to Herceg Novi.     

Influence of meteorological factors and polluting environment on rain chemistry and wet deposition in a rural area near Chimay,Belgium

This paper focuses on a detailed analysis of the effects of meteorological factors explaining the variability of rain composition.Inorganic composition of 113 individual rain events was measured from May 2002 to October 2005 at a rural site near Chimay, in the western part of the Belgian Ardennes. Original models were fitted for each studied ion (H⁺, Mg²⁺, Ca²⁺, K⁺, NH₄⁺, Na⁺, Cl⁻, NO₃⁻ and SO₄²⁻) to relate rain event concentration or wet deposition to the rainfall volume (R), the length of the antecedent dry period (ADP), the volume of the previous event (R_prev) as well as to the mean wind speed and the prevailing wind direction during both the dry and the rainy periods. These variables explained from 32% (H⁺) to 69% (NO₃⁻) of rain concentration variability. Concentrations decreased logarithmically with increasing R values except in case of H⁺ for which a positive effect of rain volume on rain concentration was observed. ADP affected positively rain concentrations of all ions excluding K⁺ and H⁺ for which, respectively, a nonsignificant and a negative effect of this variable was observed. Increasing R_prev strengthened the effect of the variable R on H⁺, Mg²⁺, Ca²⁺, Na⁺, NH₄⁺ and SO₄²⁻ concentrations while it softened the effect of ADP on NO₃⁻ concentrations. Wind speed and direction during dry and rainy periods explained together from 8% (K⁺) to 38% (Na⁺) of rain concentration total variability. R² coefficients of the wet deposition models ranged from 0.51 (K⁺) to 0.79 (SO₄²⁻). For all ions, wet deposition increased significantly with increasing R values while the effects of the other variables were similar to those on concentrations. Wind conditions during dry and rainy periods explained from 4% (H⁺) to 24% (Na⁺) of wet deposition total variability. On an annual scale, the total dry period duration, the total rainfall volume as well as the shape of the distributions of the length of the antecedent dry periods and of the rain event volume are important parameters that influence annual wet deposition.     

Atmospheric concentrations of ammonia and ammonium at an agricultural site in the southeast United States

In this study, we present ∼1 yr (October 1998–September 1999) of 12-hour mean ammonia (NH₃), ammonium (NH₄⁺), hydrochloric acid (HCl), chloride (Cl⁻), nitrate (NO₃⁻), nitric acid (HNO₃), nitrous acid (HONO), sulfate (SO₄²⁻), and sulfur dioxide (SO₂) concentrations measured at an agricultural site in North Carolina's Coastal Plain region. Mean gas concentrations were 0.46, 1.21, 0.54, 5.55, and 4.15 μg m⁻³ for HCl, HNO₃, HONO, NH₃, and SO₂, respectively. Mean aerosol concentrations were 1.44, 1.23, 0.08, and 3.37 μg m⁻³ for NH₄⁺, NO₃⁻, Cl⁻, and SO₄²⁻, respectively. Ammonia, NH₄⁺, HNO₃, and SO₄²⁻ exhibit higher concentrations during the summer, while higher SO₂ concentrations occur during winter. A meteorology-based multivariate regression model using temperature, wind speed, and wind direction explains 76% of the variation in 12-hour mean NH₃ concentrations (n=601). Ammonia concentration increases exponentially with temperature, which explains the majority of variation (54%) in 12-hour mean NH₃ concentrations. Dependence of NH₃ concentration on wind direction suggests a local source influence. Ammonia accounts for >70% of NH_x (NH_x=NH₃+NH₄⁺) during all seasons. Ammonium nitrate and sulfate aerosol formation does not appear to be NH₃ limited. Sulfate is primarily associated ammonium sulfate, rather than bisulfate, except during the winter when the ratio of NO₃⁻–NH₄⁺ is ∼0.66. The annual average NO₃⁻–NH₄⁺ ratio is ∼0.25.     

Ionic composition of TSP and PM2.5 during dust storms and air pollution episodes at Xi'an,China

TSP and PM_2.5 samples were collected at Xi'an, China during dust storms (DSs) and several types of pollution events, including haze, biomass burning, and firework displays. Aerosol mass concentrations were up to 2 times higher during the particulate matter (PM) events than on normal days (NDs), and all types of PM led to decreased visibility. Water-soluble ions (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, F^?, Cl^?, NO₃^?, and SO₄^2?). were major aerosol components during the pollution episodes, but their concentrations were lower during DSs. NH₄⁺, K⁺, F^?, Cl^?, NO₃^?, and SO₄^2? were more abundant in PM_2.5 than TSP but the opposite was true for Mg²⁺ and Ca²⁺. PM collected on hazy days was enriched with secondary species (NH₄⁺, NO₃^?, and SO₄²) while PM from straw combustion showed high K⁺ and Cl^?. Firework displays caused increases in K⁺ and also enrichments of NO₃^? relative to SO₄^2?. During DSs, the concentrations of secondary aerosol components were low, but Ca²⁺ was abundant. Ion balance calculations indicate that PM from haze and straw combustion was acidic while the DSs samples were alkaline and the fireworks' PM was close to neutral. Ion ratios (SO₄^2?/K⁺, NO₃^?/SO₄^2?, and Cl^?/K⁺) proved effective as indicators for different pollution episodes.     

Chemical and strontium isotope characterization of rainwater in karst virgin forest,Southwest China

Strontium isotope ratios and concentrations of Ca²⁺, NH₄⁺, Na⁺, K⁺, Mg²⁺, Cl^?, SO₄^2?, NO₃^? and Al³⁺, Sr²⁺ were measured for 52 rainwater samples collected in virgin forest in a rural region between May 2007 and Dec. 2008. The rainwater pH values vary from 4.1 to 7.2 with a volume weight mean (VWM) value of 5.40. 40 of 52 samples have pH value above 5.0, indicating that the regional rainwater was not acidic. Among anions and cations, sulphate concentration (40.4 μeq l^?1, VWM) is the highest in the rainwater, followed by ammonium and calcium (30.2 and 20.8 μeq l^?1, VWM). Rainwater quality is characterized by low salinity and neutralized pH.The chemical compositions and ⁸⁷Sr/⁸⁶Sr ratios of the rainwater samples vary considerably. Using Na⁺ concentration as an indicator of marine origin, the proportions of sea salt and crustal elements were estimated from elemental ratios. The ⁸⁷Sr/⁸⁶Sr ratios were used to characterize different sources base on the data sets of this study and those from literatures. Such sources include weathering of limestone (⁸⁷Sr/⁸⁶Sr = 0.7075), remote soil dust (⁸⁷Sr/⁸⁶Sr > 0.7135) and anthropogenic source (fertilizers: ⁸⁷Sr/⁸⁶Sr = 0.7079). The results of the present study suggest that one likely source for high ammonium and calcium concentration is local soil. Due to a large contribution of these cations to the sulphate neutralization action, the rainwater in this region displays non-acidity, and thus has not significant environmental impact. The wet precipitation in the karst virgin forest in Guizhou province is strongly influenced by natural sources rather than anthropogenic sources.     

Chemical characteristics of precipitation at metropolitan Newark in the US East Coast

To investigate the chemical characteristics of precipitation in the polluted coastal atmosphere, a total of 46 event-based precipitation samples were collected using a wet-only automatic precipitation collector from September 2006 to October 2007 at metropolitan Newark, New Jersey in the US East Coast. Samples were analyzed by ion chromatography for the concentrations of major inorganic ions (Cl⁻, NO₃⁻, SO₄²⁻, F⁻, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺) and organic acid species (CH₃COO⁻, HCOO⁻, CH₂(COO)₂²⁻, C₂O₄²⁻). Selected trace metals (Sb, Pb, Al, V, Fe, Cr, Co, Ni, Cu, Zn, Cd) in samples were determined by ICPMS. Mass concentration results show that SO₄²⁻ was the most dominant anion accounting for 51% of the total anions, controlling the acidity of the precipitation. NH₄⁺ accounted for 48.6% of the total cations, dominating the precipitation neutralization. CH₃COO⁻ and HCOO⁻ were the two dominant water-soluble organic acid species, accounting for 42% and 40% of the total organic acids analyzed, respectively. Al, Zn and Fe were the three major trace metals in precipitation, accounting for 34%, 27%, and 25% of the total mass of metals analyzed. The pH values in precipitation ranged from 4.4 to 4.9, indicating an acidic nature. Enrichment Factor (EF) Analysis showed that Na⁺, Cl⁻, Mg²⁺ and K⁺ in the precipitation were primarily of marine origin, while most of the Fe, Co and Al were from crust sources. Pb, V, Cr, Ni were moderately enriched with EFs ranging 43–410, while Zn, Sb, Cu, Cd and F⁻ were highly enriched with EFs > 700, indicating significant anthropogenic influences. Factor analysis suggests 6 major sources contributing to the observed composition of precipitation at this location: (1) nitrogen-enriched soil, (2) secondary pollution processes, (3) marine sources, (4) incinerations, (5) oil combustions, and (6) malonate–vanadium enriched sources. To further explore the source–precipitation event relationships and seasonality, cluster analysis was performed for all precipitation events. Results show that about half of the precipitation events were characterized by mixed sources. Significant influences of nitrogen-enriched soil and marine sources were associated with precipitation events in spring and autumn, while secondary pollution processes, incineration and oil combustion contributed greatly in summer.     

Deposition of sulphur,nitrogen and acidity in precipitation over Ireland: chemistry,spatial distribution and long-term trends

The chemical composition of pollutant species in precipitation sampled daily or weekly at 10 sites in Ireland for the five-year period, 1994–1998, is presented. Sea salts accounted for 81% of the total ionic concentration. Approximately 50% of the SO₄²⁻ in precipitation was from sea-salt sources. The proportion of sea salts in precipitation decreased sharply eastwards. In contrast, the concentration of NO₃⁻ and the proportion of non-sea-salt SO₄²⁻ increased eastwards reflecting the closer proximity to major emission sources. The mean (mol_c) ratio of SO₄²⁻:NO₃⁻ was 1.6 for all sites, indicating that SO₄²⁻ was the major acid anion.The spatial correlation between SO₄²⁻, NO₃⁻ and NH₄⁺ concentrations in precipitation was statistically significant. The regional trend in NO₃⁻ concentration was best described by linear regression against easting. SO₄²⁻ concentration followed a similar pattern. However, the regression was improved by inclusion of elevation. Inclusion of northing in the regression did not significantly improve any of the relationships except for NH₄⁺, indicating a significant increase in concentrations from northwest to southeast.The spatial distribution of deposition fluxes showed similar gradients increasing from west and southwest to east and northeast. However, the pattern of deposition shows the influence of precipitation volume in determining the overall input. Mean depositions of sulphur and nitrogen in precipitation were ≈30 ktonnes S yr⁻¹ and 48 ktonnes N yr⁻¹ over the five-year period, 1994–1998, for Ireland.Least-squares linear regression analysis indicated a slight decreasing trend in precipitation concentrations for SO₄²⁻ (20%), NO₃⁻ (13%) and H⁺ (24%) and a slight increasing trend for NH₄⁺ (15%), over the period 1991–1998.     

Seasonal variations of acidic air pollutants in Seoul,South Korea

The annular denuder system (ADS) was used to characterize seasonal variations of acidic air pollutants in Seoul, South Korea. Fifty- four 24 h samples were collected over four seasons from October 1996 to September 1997. The annual mean concentrations of HNO₃, HNO₂, SO₂ and NH₃ in the gas phase were 1.09, 4.51, 17.3 and 4.34 μg m^-3, respectively. The annual mean concentrations of PM_2.5(d_p≤2.5 μm in aerodynamic diameter, 50% cutoff), SO^2-₄, NO^-₃ and NH⁺₄ in the particulate phase were 56.9, 8.70, 5.97 and 4.19 μg m^-3, respectively. All chemical species monitored from this study showed statistical seasonal variations. Nitric acid (HNO₃) and ammonia (NH₃) exhibited substantially higher concentrations during the summer, while nitrous acid (HNO₂) and sulfur dioxide(SO₂) were higher during the winter. Concentrations of PM_2.5, SO^2-₄, NO^-₃ and NH⁺₄ in the particulate phase were higher during the winter months. SO^2-₄, NO^-₃ and NH⁺₄ accounted for 26–38% of PM_2.5. High correlations were found among PM_2.5, SO^2-₄, NO^-₃ and NH⁺₄. The mean H⁺ concentration measured only in the fall was 5.19 nmole m^-3.     

Study of aerosol transport through precipitation chemistry over Arabian Sea during winter and summer monsoons

Precipitation samples over the Arabian Sea collected during Arabian Sea Monsoon Experiment (ARMEX) in 2002–2003 were examined for major water soluble components and acidity of aerosols during the period of winter and summer monsoon seasons. The pH of rain water was alkaline during summer monsoon and acidic during winter monsoon. Summer monsoon precipitation showed dominance of sea-salt components (∼90%) and significant amounts of non-sea salt (nss) Ca²⁺ and SO₄²⁻. Winter monsoon precipitation samples showed higher concentration of NO₃⁻ and NH₄⁺ compared to that of summer monsoon, indicating more influence of anthropogenic sources. The rain water data is interpreted in terms of long-range transport and background pollution. In summer monsoon, air masses passing over the north African and Gulf continents which may be carrying nss components are advected towards the observational location. Also, prevailing strong southwesterly winds at surface level produced sea-salt aerosols which led to high sea-salt contribution in precipitation. While in winter monsoon, it was observed that, air masses coming from Asian region towards observational location carry more pollutants like NO₃⁻and nss SO₄²⁻ that acidify the precipitation.     

Quality of roof runoff waters from an urban region (Gda sk, Poland)

The paper presents the results of testing of roof runoff waters from buildings in the city of Gda sk (Poland), carried out as a part of a broader research project aimed at the determination of pollutant levels in precipitation. The analytes determined included volatile organohalogen compounds, petroleum hydrocarbons, Na⁺, K⁺, NH₄⁺, Mg²⁺, Ca²⁺, F⁻, Cl⁻, NO₂⁻, NO₃⁻, PO₄³⁻, SO₄²⁻ ions, as well as organonitrogen, organophosphorus and organochlorine pesticides. In addition, the toxicity and pH of the samples were examined. The samples were collected over a period of six months, during or immediately following precipitation events. More than half of the samples (25) were found to be toxic, with inhibition exceeding 20%. The toxicity was weakly correlated to the levels of organonitrogen and organophosphorus pesticides in runoff waters. It was established that at least in some cases the roofing material affected the levels of the pollutants found in the samples.     

Monsoon rain chemistry and source apportionment using receptor modeling in and around National Capital Region (NCR) of Delhi,India

Studies on monsoon precipitation chemistry were carried out to understand the nature of rainwater and sources of pollution at eight different locations in and around the National Capital Region (NCR) of Delhi during southwest monsoon in the years 2003–2005. These sites were Bulandshahr (BUL), Garhmuktesar (GAR), Muradnagar (MUR), Sardhana (SAR), Panipat (PAN), Charkhi Dadri (CHA), Hodal (HOD) and Bahror (BAH). The rainwater samples, collected at these locations, were analyzed for major anions, cations and pH. The data were assessed for its quality. In general, the order of concentrations of major ions was observed to be: Ca²⁺>SO₄²⁻>HCO₃⁻>NH₄⁺>Cl⁻>NO₃⁻>Na⁺>Mg²⁺>K⁺>F⁻. The average pH of rainwater at these stations was observed to be 6.39, ranging from 5.77 to 6.62, indicating alkaline nature. However, a few rain events, 31% at Panipat, 12% at Muradnagar and 29% at Sardhana, were observed to be acidic (pH<5.6). Acidity observed at Panipat and Muradnagar is attributed to industrial influence but at Sardhana to weak organic acids contributed by surrounding vegetation. No definite trends are found for most of the components at all the sites. However, concentrations of Cl⁻ at Bulandshahr; NO₃⁻ at Muradnagar and Hodal; F⁻ at Panipat and Bahror; Na⁺ at Bulandshahr; K⁺ at Bahror and Bulandshahr; Ca²⁺ at Bulandshahr, Muradnagar, Charkhi Dadri and Sardhana; Mg²⁺ at Panipat, Bahror, Bulandshahr, Hodal and Sardhana have increased from 2003 to 2005. For source identification, principal component analysis (PCA) was made, which showed that in general, at all the sites; suspended soil–dust and sea salts which are natural sources, were identified as the most dominating. Sources like agriculture including cattle, brick kilns and industries were reflected in third or fourth PC indicating moderate influence of anthropogenic activities in this region.     

Wet-deposition fluxes of soluble chemical species and the elements in insoluble materials

From March to June 1996, eight rain events were collected by sequential sampling on time and volume basis in Kyoto University, Uji, Japan. Soluble chemical species Cl⁻, NO₃⁻, SO₄²⁻, Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺ were measured by Ion Chromatography (IC); and the elements Si, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb in insoluble materials were measured by proton-induced X-ray emission (PIXE) technique. The wet-deposition flux of a soluble chemical species (or an element in insoluble materials) was calculated by the product of the chemical species (or the element) concentration and the corresponding rain intensity. The characteristics of sequential cumulative wet-deposition flux of the soluble chemical species and the elements in insoluble materials were examined. The factor controlling wet-deposition flux was discussed.     

Comparison of forest edge effects on throughfall deposition in different forest types

This study examined the influence of distance to the forest edge, forest type, and time on Cl⁻, SO₄²⁻, NO₃⁻, and NH₄⁺ throughfall deposition in forest edges. The forests were dominated by pedunculate oak, silver birch, or Corsican/Austrian pine, and were situated in two regions of Flanders (Belgium). Along transects, throughfall deposition was monitored at distances of 0-128 m from the forest edge. A repeated-measures analysis demonstrated that time, forest type, and distance to the forest edge significantly influenced throughfall deposition of the ions studied. The effect of distance to the forest edge depended significantly on forest type in the deposition of Cl⁻, SO₄²⁻, and NO₃⁻: the edge effect was significantly greater in pine stands than in deciduous birch and oak stands. This finding supports the possibility of converting pine plantations into oak or birch forests in order to mitigate the input of nitrogen and potentially acidifying deposition.     

Characteristics of precipitation chemistry at Lushan Mountain, East China: 1992–2009

Introduction

Trends in precipitation pH and conductivity during 1992?C2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35?C5.01 and showed a statistically very significant (P?P?Results and discussions Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO ₄ ^2? and NO ₃ ^? were the main anions, and NH ₄ ⁺ and Ca²⁺ the main cations. The anion to cation ratio was 0.8?C1.0, and that of [SO ₄ ^2? ] to [NO ₃ ^? ] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH ₄ ⁺ ] to [Ca²⁺] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl^?] to [Na⁺] was about 0.67, somewhat lower than that of natural precipitation.

Conclusions

Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry.