Chemical Characteristics Of Precipitation Research Articles

Chemical Characteristics and Ionic Sources of Precipitation in the Source Region of the Yangtze River

Using 64 precipitation samples collected from June to September 2013 in the Dongkemadi Basin in the source region of the Yangtze River, the pH, conductivity, and main ionic concentration characteristics of precipitation were analyzed. The main ionic sources of precipitation and their relationships with atmospheric circulation were examined using factor analysis, correlation analysis, enrichment factor analysis, and backward trajectory analysis. The results showed that the range of precipitation pH values varied from 5.26 to 9.25 with a weighted average of 6.70, and conductivity ranged from 0.23 to 28.70 μS·cm-1 with a weighted average of 3.45 μS·cm-1. The conductivity of precipitation was lower than for the Mt. Waliguan basin (China Global Atmosphere Watch baseline observatory). The total ionic concentrations in the precipitation ranged from 7.0 to 376.9 μeq·L-1 with a weighted average of 40.8 μeq·L-1. The ranked order of ionic concentrations was HCO3- > NH4+ > Ca2+ > NO3- > SO42- > Na+ > Cl- > K+ > Mg2+. HCO3-, NH4+,Ca2+, and NO3- were the dominant ions, which accounted for 74.75% of the total ionic concentration. Fractional acidity (FA) analysis showed that 97.8% of the precipitation acidity was neutralized by alkaline constituents. Neutral factor (NF) analysis indicated that NH4+ and Ca2+ were the dominant neutralization constituents in the precipitation. The precipitation ions in this study area were mainly derived from terrestrial material, while input from marine sources was relatively low. Backward trajectory analysis revealed that the total ionic concentrations varied significantly between the different sources, which followed the order of local sources>westerly sources>monsoon sources. This indicates that different atmospheric circulation conditions and air mass sources have a significant influence on the chemical composition of precipitation in this area. To some extent, the chemical characteristics of precipitation could reflect the air quality and background values for remote areas due to the limited effect of human activities. The results of this study provide a scientific basis for the protection of water quality and the assessment of the impact of human activities on the atmospheric environment in the source region of the Yangtze River.

Stable isotopes and chemical characteristics of precipitation in Hangzhou and Huzhou, East China.

Atmospheric precipitation is a very important link in the water cycle. The characteristics of major ions (n= 341) and stable isotopes (δ2H, δ18O; n= 157) were analysed in Hangzhou and Huzhou, which are economically prosperous cities in East China. The δ2H and δ18O values of precipitation ranged from - 109.70 to 21.30‰ and from - 14.87 to - 0.95‰, respectively. Compared with the local meteoric water line (LMWL) of China, the slope and intercept of the LMWL were much higher in Hangzhou and Huzhou, which is related to the effects of the humid climate and less secondary evaporation. The δ2H and δ18O values were highest in spring because of the influence of air masses from the northern Asian continent and other nearby sources. In contrast, the air masses from the South China Sea and the western Pacific Ocean in the summer had the lowest δ2H and δ18O. The dominant ions in precipitation indicate that Ca2+, HCO3-, SO42-, NH4+ and NO3- are the main ions of precipitation in Hangzhou and Huzhou, and the dilution of precipitation leads to lower concentrations of ions in spring and summer, similar to the values found in most Chinese cities. The increase in motor vehicle use resulted in a lower [SO42-]/[NO3-] ratio (1.64) of precipitation, indicating mixed acid rain in Hangzhou and Huzhou (HZS). Based on a combination of the correlation analysis, enrichment factors and source contributions, we determined that SO42- and NO3- were introduced mainly from anthropogenic activities such as coal combustion and vehicle exhaust, accounting for 89% and 99%, respectively. The strong correlation between Cl- and Na+, as well as Ca2+, Mg2+ and K+, indicates that these ions commonly have marine and crustal origins, respectively, and 40% of Mg2+ comes from a marine source.

Chemical composition of precipitation in Shenzhen, a coastal mega-city in South China: Influence of urbanization and anthropogenic activities on acidity and ionic composition

Rainwater samples from Shenzhen in south China were collected over the period of a year, and the chemical compositions were measured with the main purpose of understanding the acidification of rainwater and the controlling factors. The pH value of precipitation ranged from 3.72 to 6.77, with a volume-weighted mean (VWM) value of 4.29, and the acid rain frequency was 97%. The VWM concentrations of anions and cations followed the order of SO42− > Cl− > NO3− and Na+ > Ca2+ > NH4+ > Mg2+ > K+, respectively. Air mass back-trajectory and positive matrix factorization analyses indicated that sources of ions in rainwater were mainly from sea salt, soil dust and anthropogenic activities. Compared with other areas in China, the rainwater of Shenzhen has the lowest values of the NP/AP, ∆pH and NF values of Ca2+ and NH4+, indicating that the lack of the capacity for neutralization could be the main reason for the severe acid rain problem. It is noteworthy that the rain acidification tendency is obvious, and the pH value has reduced by 1.0 units since the 1980s. Based on a comparison of the chemical compositions of the rainwater from different historical periods, the NO3− concentration was found to have increased consistently, whereas the NH4+ concentration maintained a decreasing trend since 1980. On the other hand, the nss-SO42− and nss-Ca2+ concentrations increased after 1980 and then decreased after 1994. Meanwhile, the decreasing pH was accompanied by a decreasing NP/AP ratio. These results suggest that the changes in human activities at different stages of urban development can lead to a synergistic change in the chemical characteristics of precipitation. Both an increase in the acidic species emissions (especially NOX) due to rapid economic development and a decrease in the alkaline ions concentration due to urbanization have resulted in the rain acidification tendency in Shenzhen.

Chemical Characteristics of Precipitation in a Typical Urban Site of the Hinterland in Three Gorges Reservoir, China

Major water-soluble ions were analyzed for two-year precipitation samples in Wanzhou, a typical urban site of the hinterland of Chinese Three Gorges Reservoir. The pH values of the precipitation were in the range of 4.0 to 8.3, and the volume-weighted mean (VWM) value was 5.0. The concentration order of anions and cations was as follows: SO42->NO3->Cl->F- and NH4+>Ca2+>Na+>K+>Mg2+, respectively. Good correlations were found between SO42- and NH4+, SO42- and Ca2+, NO3- and NH4+, and NO3- and Ca2+, implying their co-occurrence in the precipitation, most likely as (NH4)2SO4, (NH4)HSO4, NH4NO3, CaSO4, and Ca(NO3)2. The sum of all measured ions was 416.4 μeq L−1, indicating serious air pollution in Wanzhou. NH4+ and Ca2+ were the most important ions neutralizing the acidic compounds in the precipitation; their major sources included agricultural activity and crustal dust. Local anthropogenic activities, for example, coal burning and traffic related sources, contributed most of SO42- and NO3-. The equivalent concentration ratio of SO42-/NO3- was 4.5, indicating that excessive emission of sulfur was the main reason leading to the precipitation acidity in Wanzhou. However, this ratio was lower than the ratio (5.9) in 2000s in Wanzhou, indicating that the contribution of nitric acid to the acidity of precipitation was strengthening.

Chemical Characteristics of Precipitation during Winter Season over Delhi: Source Identification of Measured Species

Chemical Characteristics of Precipitation during Winter Season over Delhi: Source Identification of Measured Species

Chemical characteristics of precipitation and wet deposition of major ions in Liaozhong County of Liaoning Province, Northeast China

The chemical characteristics of precipitation were analyzed based on the chemical composition of principal ionic within acid rain (from February 2007 to January 2008) of Liaozhong Meteorological Station located in Malong Village in Liaozhong County of Northeast China, meteorological conditions on the corresponding period ground, and variation of several air pollutants concentration. The results indicated that: (1) The precipitation average pH value of all samples was 4.76; the frequency of acid rain during the observation period was 70.7%; the frequency was 82.8% in summer and autumn. (2) In the chemical composition of precipitation, the primary anions were SO42- and NO3-; the primary cations were NH4+ and Ca2+. (3) All concentration of anions was higher in summer and winter, but relatively low in spring and autumn. This showed that the relationship between regional rainfall acidification and pollution was not significant. (4) Rainwater acidity and nearly floor gaseous pollution concentration were differe...

Characteristics of inorganic ions in precipitation at different altitudes in the Yulong Snow Mountain, China

The present study investigated the chemical composition of summer precipitation at different altitudes in Yulong Snow Mountain, hoping to obtain some basic information about the chemical characteristics of precipitation. A couple of precipitation samples at different altitudes in the Yulong Snow Mountain area in southeastern China were collected from July 26 to July 31, 2005 for chemical analyses. Sea-salt tracer analysis showed that Cl- and Na+ had high proportion from marine sources, while the other ions mainly were from non-marine sources. Statistics showed that the cation concentrations ranged from 0.51 to 5.26 mg L-1 and anion concentrations ranged from 0.99 to 4.90 mg L-1. Further analysis showed that terrestrial ions, especially from the proximal terrestrial sources, largely affected the ion concentrations in precipitation. Ion concentrations of precipitation were correlated significantly with local atmospheric circulation at altitude 2,950-4,800 m, and also correlated closely with human activities at altitude 2,400-2,950 m. Limestone, the majority of local rocks, caused high cation concentrations in precipitation, such as Ca2+ and Mg2+. The majority of vapors in the region came from the Indian Ocean whereas parts came from the eastern Pacific. The inorganic ions in precipitation increased significantly in the Yulong Snow Mountain area during this century. Compared with most of the high altitude Mountains in China, the precipitations in the Yulong Snow Mountain area had higher concentrations of inorganic ions and low acidic ion concentrations. The conclusions can provide a basis for study of regional climate characteristics, environment and ecological characteristics of Yulong Snow Mountain area.

Chemical characteristics of precipitation in central Liaoning Province, Northeast China

The chemical characteristics of precipitation were analyzed based on the chemical composition of principal ionic within acid rain (from February 2007 to January 2008) of Liaozhong Meteorological Station (LMS) located in Malong Village in central Liaoning Province of Northeast China, meteorological conditions on the corresponding period ground, and variation of several air pollutants concentration. The results indicated that (1) the precipitation of LMS was acidic; average pH of all samples was 4.76; the frequency of acid rain during the observation period was 70.7%; the frequency was 82.8% in summer and autumn; and the acidity was stronger in larger rainfall season; (2) in the chemical composition of precipitation, the primary anions were SO42- and NO3-; the primary cations were NH4+ and Ca2+; the ratio of SO42-/ NO3- was 2.9; and the ratio of Na+/Cl- was larger than 1;(3) all concentration of anions was higher in summer and winter, but relatively low in spring and autumn. This showed that the relationship between regional rainfall acidification and pollution was not significant. The correlation between (∑ anionic / ∑ cationic) and pH was not obvious among the measured 9 kinds of main anions and cations, which explained the main 9 kinds of anions and cations in the current acid rain observation could not completely include precipitation ions composition; and (4) rainwater acidity and near floor gaseous pollution concentration were different from each other, and pH and NOx, CO, NO2 and O3 concentrations showed significant negative correlation, but was not obvious with SO2concentration. However, the pH and alkaline pollutants, such as particulate, was positively correlative. Key words: Precipitation, acid rain, chemical characteristics, central Liaoning Province of China.

Major Ionic Composition of Precipitation in the Shigatse Region, Southern Tibetan Plateau

Abstract. In order to investigate the chemical characteristics of precipitation on Tibetan Plateau, a total of 34 precipitation samples have been collected from individual precipitation events at the Shigatse Meteorological Station located in the south Tibetan Plateau in 2008. All samples were analyzed for major cations (NH4+, Na+, K+, Ca2+ and Mg2+) and anions (Cl−, NO3− and SO42−), conductivity and pH. The result showed that precipitation pH values ranged from 6.79 to 9.21 with an average value of 7.86. HCO3− and Ca2+ were the major ions detected in the samples, occupied 39% and 35% of the total ion mass, 80% of the total anion mass and 69% of the total cations mass, respectively. Factor analysis indicated that regional crustal dust, lake salt and local combustion products of residents were the main sources of the ionic compositions of precipitation of Shigatse region. Trajectory cluster analysis indicated that 97.1% of the air masses reaching Shigatse originated from the south, which passed through some pollution regions, as southeast Indian, Bangladesh.

Chemical characteristics of precipitation at Nanping Mangdang Mountain in eastern China during spring

To study the characteristics of precipitation in eastern China, an automatic sampler was used to collect rainwater samples from 19 precipitation events at Mangdang Mountain, Nanping City, Fujiang Province, in the spring of 2009. We used ion chromatography to analyze the ionic components and concentrations, and inductively coupled plasma mass spectrometry (ICP-MS) to analyze element compositions and contents. The results demonstrated remarkable acidic characteristics: in more than 80% of precipitation events the pH was less than 5.6, with an average of 4.81. Mass concentration results showed SO 4 2− was the main anionic component (36.2% of the total anion mass), while NH 4 + was the main cationic component (47.7% of the total cation mass) and main ion for acidity neutralization in the rainwater. Organic acid content accounted for 30.9% of total anion mass. The main trace metals were Ca, K, and Na. The SO 4 2−/NO 3 − ratio was 1.4, indicating that precipitation in this region was influenced by complex air pollution – the product of individual coal-burning combined with vehicle exhaust pollution. Correlation analysis of the chemical composition of the precipitation indicated that acidity in this region was determined by a combination of all acidic and neutralization ions rather than any single ion component. The results also showed that Na + and Cl − contributions were mainly by seawater; Mg 2+ by seawater and crustal materials; the NH 4 +, K +, Ca 2+, NO 3 − and SO 4 2− by anthropogenic sources; the trace metals were from the Earth's crust; and organic acids were potentially from combustion of biomass.

Chemical composition of precipitation and its sources in Hangzhou, China

To understand the origin and chemical characteristics of precipitation in Hangzhou, rainwater samples were collected from June 2006 to May 2008. All samples were analyzed for pH, electrical conductivity, and major ions (NH⁴⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺, SO₄²⁻, NO₃⁻, F⁻, and Cl⁻). Acidification of precipitation in Hangzhou was serious with volume-weighted mean pH value of 4.5, while frequency of acid rain was 95%. The calculated SO₄²⁻/NO₃⁻ ratio in Hangzhou precipitation was 2.87, which indicated that the precipitation of Hangzhou belonged to sulfate-based acid rain. The results of acid neutralization analysis showed that not all the acidity in the precipitation of Hangzhou was neutralized by alkaline constituents. The results of sea salt contribution analysis showed that nearly all SO₄²⁻, Ca²⁺, and Mg²⁺ and 33.7% of K⁺ were of non-sea origins, while all Na⁺ and Cl⁻ and 66.3% of K⁺ originated from sea sources. The principal component analysis which was used to analyze the sources of various ions indicated that chemical compositions of precipitation in Hangzhou mainly came from terrestrial sources, factory emissions, fuel wood burning, and marine sources.

Chemical Characteristics and Cause Analysis of Precipitation in the South of Liaodong Peninsula

Based on the acid rain observation data of 12 observation points from 2007 to 2009 in Dalian Environmental Monitoring Center and Dalian Meteorological Bureau, the paper analyzes the spatial and temporal distribution status of acid rain and the chemical characteristics of precipitation in the south of Liaodong Peninsula, makes an initial cause analysis, and does the Spearman rank correlation coefficient test of materials since 2004. The results show that, the frequency of acid rain shows a trend of significant increase while the pH value shows a clear downward trend, it has already been at medium level of acid rain. The equivalent concentration ratio of sulfate to nitrate ion in precipitation is 2.7. The acid rain is not entirely caused by the local pollutant emission but affected by a wide range of regional pollution. The enhancement of the acid rain is because that the control of pollutant emissions results in the decrease of neutralization of alkaline substances.

Chemical characteristics of precipitation at three Chinese regional background stations from 2006 to 2007

Studies on the chemical composition of wet precipitation were carried out from September 2005 to September 2007 at three Chinese regional background stations. All samples were analyzed for pH and major ions (F − , Cl − , NO − 3 , SO 4 2− , K + , Na + , Ca 2+ , Mg 2+ and NH 4 + ). Of the three stations, the lowest pH value was observed at Lin'an. The highest ion concentrations (SO 4 2− , NO 3 − and NH 4 + ) occurred at Shangdianzi. By referring to former studies and observations of reactive gases at the three stations, pH and chemical composition trends from 1985 to 2007 were analyzed. Compared to values from 1985 to 1997, the pH values in the precipitation of all three stations were significantly lower and [NO 3 − ] was higher. [SO 4 2− ] in the precipitation also increased at Shangdianzi and Longfengshan. Due to the neutralization of alkaline aerosols in northern China, precipitation at Shangdianzi and Longfengshan was not as severely acidified as at Lin'an. However, the neutralizing effects of the aerosols have decreased in recent years. Significant correlations between ions were found at each of the three stations. Principal component analysis was also performed to find possible sources of the major ionic species. Acid rain research in China has traditionally focused on urban sites, however the present study of background stations revealed significant effects of long-range transported air pollutants on rural areas in China.

Chemical characteristics of precipitation in Okinawa Island, Japan

This study examined the chemical composition and characteristics of precipitation collected from March 2003 to February 2005 in the central part of Okinawa Island, Japan. Chloride ions contributed most to the total ion equivalent concentration, and followed in order by Na +>Mg 2+, SO 4 2−>Ca 2+>H +, NH 4 +, K +>NO 3 −, HCO 3 −. Concentrations of Na +, K +, Ca 2+, Mg 2+, Cl −, and sea salt SO 4 2− (ss-SO 4 2−) increased from summer to autumn and decreased from winter to spring. In contrast, concentrations of NH 4 +, NO 3 − (except for July 2004), non-sea salt SO 4 2− (nss-SO 4 2−), and H + were lower in summer and higher in winter. During periods with typhoons, concentrations of sea salt components, such as Na + and Cl −, increased while NO 3 − and nss-SO 4 2− concentrations decreased. Wet deposition driven by typhoons accounted for about 77% of the total annual wet deposition. The pH values ranged from 3.89 to 7.61. Acid rain (pH<5.6) occurred in 72% of the collected samples, even though Okinawa Island is considered to be an unpolluted area. Principal component analysis indicated three main origins of the chemical components in precipitation: (1) sea salt generated from local surrounding ocean (Na +, K +, ss-Ca 2+, Mg 2+, Cl −, and ss-SO 4 2−), (2) soil generated from local land (nss-Ca 2+ and D-SiO 2), and (3) anthropogenic source of Asian Continent (NH 4 +, NO 3 −, and nss-SO 4 2−).

Effects of wet deposition on optical properties of the atmosphere over Bermuda and Barbados

Substantial spatial and temporal variabilities in chemical and physical properties of aerosols complicate attempts to model associated influences on global climate. Although wet deposition is the major mechanism by which most aerosols are removed from the atmosphere, direct effects of precipitation on radiative properties of the atmosphere are not well understood. To address this issue, attenuation coefficients for total insoluble constituents (ACt) and for nonvolatile (at 500°C) insoluble constituents (ACnv; primarily crustal dust) of precipitation at Bermuda and Barbados were measured at six wavelengths between 414 and 859 nm. Coefficients for volatile (at 500°C) insoluble constituents (ACv; primarily carbonaceous species) were calculated by difference. Between April and September, ACt at Bermuda was dominated by mineral constituents transported from North Africa, whereas carbonaceous species from North America were relatively low and exhibited no systematic seasonal variability. ACt and ACnv at Barbados were dominated by mineral dust, especially between April and September. Relative to ACv, ACnv decreased more rapidly with increasing wavelength. The wavelength dependencies of ACs for volatile and nonvolatile constituents at Bermuda were statistically indistinguishable from those at Barbados. The optical and chemical characteristics of precipitation were compared with scattering and absorption by ambient aerosols in associated air parcels to evaluate the influence of scavenging on the radiative properties of air. Although discernible relationships were evident, the small number of cases limited their applicability as reliable empirical predictors. However, these data do provide useful constraints for validating models of aerosol scavenging and wet removal on the optical properties of the troposphere.

山形県米沢市における降水の化学的特徴

山形県米沢市における降水の化学的特徴

Chemical characteristics of precipitation in NH 3-affected areas

Effects of gaseous ammonia (NH 3) on precipitation chemistry were studied in four areas with a significant emission density as a result of animal manure production by intensive stockbreeding activities. In these NH 3-affected areas the quantity of ammonium (NH 4 +) and sulphate (SO 4 2−) in atmospheric precipitation was 1.5–4 times higher than in relatively remote areas, whereas 70–90% of the deposition of nitrogen consisted of NH x compounds. Particularly within a distance of 1 km downwind point-sources of NH 3 emission bulk precipitation was less acidic and showed enhanced concentrations of NH 4 and SO 4 2− than at larger distances. NH 3 is the dominant agent which reacts with, and neutralizes, acid compounds in the atmosphere by forming (NH 4) 2SO 4. Annual mean volume-weighted concentrations of NH 4 + reached values of 179–369 μmol ℓ −1 those of SO 4 2− were 90–145 μmol ℓ −1. The highest measured total amount of NH x compounds deposited on an open water surface was 62 kg N ha −1 a −1. In the studied areas NH 4 + is the dominant form of N in atmospheric precipitation which, together with SO 4 2−, falls on and enters the biosphere.

Chemical characteristics of precipitation and hydrogen input in throughfall and stemflow under some eastern Canadian forest stands

At the Acadia Forest Experiment Station (AFES) in central New Brunswick chemical characteristics of rain samples collected at five different locations were determined during the 1977–1981 period. Throughfall and stemflow samples from six softwood and three hardwood stands were collected and chemically characterized starting from the early 70's. In 1976 two of four plots in each of the stands were treated with urea at a rate of 225 kg N•ha−1. Both the quantities of rain and their pH values varied considerably between collections, months, and years. The weighted mean pH of summer (May–October) rain collected intensively during the 1977–1981 period ranged from 4.5 to 5.1, with an overall weighted average value of 4.75 for the 5 years. Sulfur and nitrate N measured during May–October 1982 amounted to 6.18 and 1.52 kg•ha−1, respectively, for the 6-month period. The concentration of hydrogen ion in the throughfall was less than that in the rain. Hardwood throughfall had lower hydrogen levels (higher pH) than the softwood throughfall. The pH of the stemflow from softwoods was lower than that of rain in most cases. Although not significantly, the hydrogen ion concentration of both throughfall and stemflow on the fertilized plots was lower than on the untreated plots. The hydrogen load of rain was reduced by all tree species, but there was considerable variation between species in their abilities to decrease total hydrogen reaching the soil.