Mass Concentrations Of Water-soluble Ions Research Articles

Main Chemical Components in Atmospheric Precipitation and Their Sources in Xi'an

In order to understand the current status of main chemical components of atmospheric precipitation in Xi'an, the pH, electrical conductivity, mass concentration of water-soluble ions and heavy metals, wet deposition fluxes, and their sources in precipitation samples in urban and suburban areas of Xi'an in 2019 were studied. The results showed that the pH, conductivity, water-soluble ions, and heavy metals in precipitation in Xi'an in winter were higher than those in other seasons. The main water-soluble ions in precipitation were Ca2+, NH+4, SO2-4, and NO-3, and the sum of these ions accounted for (88.5%±2.8)% of the total ion concentration in urban and suburban areas. The main heavy metals were Zn, Fe, and Zn and Mn; their sum accounted for (54.0%±3)% and (47.0%±8)% of the total metal concentration. The wet deposition fluxes of water-soluble ions in precipitation in urban and suburban areas were (253.2±58.4) mg·(m2·month)-1 and (241.9±61.1) mg·(m2·month)-1, respectively. They showed higher values in winter than those in other seasons. The wet deposition fluxes of heavy metals were (86.2±37.5) mg·(m2·month)-1 and (88.1±37.4) mg·(m2·month)-1, respectively, with little seasonal difference. The source analysis using PMF showed that the water-soluble ions in urban and suburban precipitation mainly came from combustion sources (57.5% and 32.32%), followed by motor vehicles (24.4% and 17.2%) and dust sources (18.1% and 27.0%). The ions in suburban precipitation were also affected by local agriculture (11.1%). Heavy metals in precipitation in urban and suburban areas mainly came from industrial sources (51.8% and 46.7%), and the contribution rate of coal and motor vehicle mixed sources in winter was 10.7% and 6.1% higher than that in summer, respectively.

Sulfate and nitrate elevation in reverse-transport dust plumes over coastal areas of China

Sulfate and nitrate formed on dust aerosols can considerably affect particles' physicochemical properties due to their high hygroscopicity. Dust reverse-transport (DRT) events can occur in eastern China when dust plumes undergo a distinct turn caused by Asian highs or cyclones, resulting in the re-appearance of the dust plume in one place but with anthropogenic pollutants mixed in. In this study, three DRT events were identified at a coastal city, Qingdao. The secondary sulfate and nitrate in PM2.5 collected during the DRT events were estimated according to the mass concentration of water-soluble ions and dust tracer metal. Several key factors, including heterogeneous reactions on aerosols, photochemical conversions in the air, and precursors’ abundance in dust plumes, affected the aging of dust plumes. In the presence of adequate ammonium and high-level oxidants in the air, sulfate and nitrate were efficiently produced under moderate/high humidity conditions when DRT events occurred to the south of Qingdao. The proportions of the secondary sulfate/nitrate in total concentrations exceeded 90%, in which 20.8%–43.1% of secondary nitrate was formed on dust particles. In contrast, when the DRT occurred to the north of Qingdao with low relative humidity and low [NH4+]/[SO42−] ratio, the growth of sulfate and nitrate was small. This study reveals a manner of efficient sulfate and nitrate formation in dust plumes in the continental atmosphere.

Measurement report: Firework impacts on air quality in Metro Manila, Philippines, during the 2019 New Year revelry

Abstract. Fireworks degrade air quality, reduce visibility, alter atmospheric chemistry, and cause short-term adverse health effects. However, there have not been any comprehensive physicochemical and optical measurements of fireworks and their associated impacts in a Southeast Asia megacity, where fireworks are a regular part of the culture. Size-resolved particulate matter (PM) measurements were made before, during, and after New Year 2019 at the Manila Observatory in Quezon City, Philippines, as part of the Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex). A high-spectral-resolution lidar (HSRL) recorded a substantial increase in backscattered signal associated with high aerosol loading ∼440 m above the surface during the peak of firework activities around 00:00 (local time). This was accompanied by PM2.5 concentrations peaking at 383.9 µg m−3. During the firework event, water-soluble ions and elements, which affect particle formation, growth, and fate, were mostly in the submicrometer diameter range. Total (>0.056 µm) water-soluble bulk particle mass concentrations were enriched by 5.7 times during the fireworks relative to the background (i.e., average of before and after the firework). The water-soluble mass fraction of PM2.5 increased by 18.5 % above that of background values. This corresponded to increased volume fractions of inorganics which increased bulk particle hygroscopicity, kappa (κ), from 0.11 (background) to 0.18 (fireworks). Potassium and non-sea-salt (nss) SO42- contributed the most (70.9 %) to the water-soluble mass, with their mass size distributions shifting from a smaller to a larger submicrometer mode during the firework event. On the other hand, mass size distributions for NO3-, Cl−, and Mg2+ (21.1 % mass contribution) shifted from a supermicrometer mode to a submicrometer mode. Being both uninfluenced by secondary aerosol formation and constituents of firework materials, a subset of species were identified as the best firework tracer species (Cu, Ba, Sr, K+, Al, and Pb). Although these species (excluding K+) only contributed 2.1 % of the total mass concentration of water-soluble ions and elements, they exhibited the highest enrichments (6.1 to 65.2) during the fireworks. Surface microscopy analysis confirmed the presence of potassium/chloride-rich cubic particles along with capsule-shaped particles in firework samples. The results of this study highlight how firework emissions change the physicochemical and optical properties of water-soluble particles (e.g., mass size distribution, composition, hygroscopicity, and aerosol backscatter), which subsequently alters the background aerosol's respirability, influence on surroundings, ability to uptake gases, and viability as cloud condensation nuclei (CCN).

Formation of marine secondary aerosols in the Southern Ocean, Antarctica

Environmental context Water soluble ions (WSIs) in aerosols, especially in marine secondary aerosols, can participate in the formation of cloud condensation nuclei (CCN) in the marine boundary layer, which can affect global climate. In our study, in-situ gas and aerosol compositions were analysed to explore the formation paths and forms of secondary aerosols in the Southern Ocean (SO) in summer. Our study provided novel data on these formation mechanisms of secondary aerosols in the SO, with potential impacts on our understanding of global climate change. Abstract Water-soluble ions (WSIs) in aerosols, especially marine secondary aerosols, may participate in the formation of cloud condensation nuclei (CCN) in the marine boundary layer and affect the global climate. However, there is still a lack of studies on the background concentrations and the formation mechanisms of marine secondary aerosols in polar areas. High time resolution concentrations of WSIs in aerosols were analysed by an in situ gas and aerosol composition monitoring system in the Southern Ocean (SO) to identify the formation of marine secondary aerosols including methanesulfonic acid (MSA), SO42− and NO3−. The average hourly mass concentration of WSIs was 663 ng m−3 and secondary aerosols accounted for 49.8 ± 20.2 % of the WSIs. SO42− and NO3− were mainly formed by homogeneous reaction, whereas homogeneous and heterogeneous reactions together contributed to the formation of MSA− in aerosols in the SO. The melting of sea ice and the increase of chlorophyll-a (Chl-a) concentration contributed to the formation of MSA−. MSA-Na, MSA-NH4+, MSA-SO42−, MSA-Mg, MSA-K and MSA-Cl existed in marine aerosols. Secondary inorganic aerosols existed mainly in the forms of NH4NO3, (NH4)2SO4, Na2SO4 and MgSO4. The results enrich the data of WSI concentrations and formation mechanisms of secondary aerosols in the SO.

Chemical Characteristics and Source Apportionment of Water-Soluble Ions in Atmosphere Aerosols over the East China Sea Island During Winter and Summer

A total of 70 total suspended particulate (TSP) samples were collected from December 2017 to February 2018 and June to August 2018 in Shengsi Islet, East China Sea. In this study, the mass concentrations of water-soluble ions in the TSP (including Na+, K+, NH4+, Mg2+, Ca2+, Cl-, SO42-, NO3-, and MSA) samplers were determined by ion chromatography. The chemical characteristics, seasonal differences, and main sources of water-soluble ions in this background aerosol site were investigated by a multiple-technique analysis combining a HYSPLIT model, correlation analysis of water-soluble ions, and primary component analysis. The results showed that the average mass concentrations of TSP and the main water-soluble inorganic ions (WSIIs) were both high in winter and low in summer; the average mass concentration of total WSIIs in winter was (26.5±16.3) μg·m-3, and in summer was (8.8±3.8) μg·m-3. Secondary inorganic ions (NO3-, SO42-, and NH4+) are the most important ionic components in TSP, which accounted for 86.2% and 74.9% of TWSIIs in winter and summer, respectively. Meanwhile, the study site was affected by seasonal temperature change, long-distance transmission, and summer biogenic sulfates. The mass concentration of nitrate was highest in winter, and the mass concentration of sulfate was highest in summer. Anthropogenic sources were the main source of nss-SO42- in atmospheric aerosols. The analysis of sulfate sources showed that contributions of biogenic sulfates to nss-SO42- were 28.1% and 5.9% in summer and winter, respectively. The results of principal component analysis indicated that the main sources of aerosol chemical composition were marine and anthropogenic sources in summer and winter, respectively. In winter, Cl- showed a certain degree of enrichment due to the influence of human activities, and the average value of the enrichment factor was 38.5%.

Diurnal Variations and Source Apportionment of Water-soluble Ions in PM2.5During Winter in Nanjing Jiangbei New Area

To gain a better understanding of the day-night variation characteristics of water-soluble ions, PM2.5 samples were continuously collected for two months in the Nanjing Jiangbei New Area during winter. The diurnal variation and sources of water-soluble ions were studied. Results showed that the mass concentration of water-soluble ions ranged from 17.07 μg·m-3 to 168.43 μg·m-3 with a mean value of (59.01±30.75) μg·m-3. The average mass concentration of water-soluble ions in daytime was higher than that in the nighttime. The concentration ratio of NO3- and NH4+ to total ion concentrations was higher at night, while SO42- and Cl- were higher during daytime. SO42-, NO3-, and NH4+ (SNA) were the dominant species of water-soluble ions in PM2.5 in Nanjing. The mass concentration of SNA on polluted days was higher than that on clean days. The ratio of the anion-cation balance (AE/CE) was larger than 1, indicating that the PM2.5 was acidic. There was a significant linear correlation between NH4+ with NO3- and SO42-, indicating that it occurred mainly in the form of NH4NO3 and (NH4)2SO4 in PM2.5. The PMF source apportionment indicated that water-soluble ions of PM2.5 were mainly derived from motor vehicle emissions, fossil fuel combustion, biomass burning, and dust in the Nanjing Jiangbei New Area.

On the characteristics of solar radiative transfer and participating media in Harbin, China

The ultimate solar radiation received by solar systems is the result of being absorbed and scattered by aerosols, and it is mainly influenced by the geometric structure and composition of the aerosol particles, which can be determined by the formation process. Samples of atmospheric aerosol particles were collected in Harbin from February to April 2019. Gravimetric analysis, transmission electron microscopy, and liquid phase ion chromatography were used to analyze the morphology, mixed structure, and water-soluble ion physicochemical properties of particulate samples. The results showed that the average concentration of particulate matter in dust weather was 648.31 μg / m³. The main mixed structure was an external mixed structure, accounting for 58%, and the mass concentration of water-soluble ions accounted for ∼3.6 % of the total suspended particles. In haze weather, the average concentration of particulate matter was 319.90 μg / m³ and the main mixed structure was a core–shell structure, accounting for 60%. The mass concentration of water-soluble ions accounted for ∼11.9 % of the total suspended particles.

Analysis of Pollution Characteristics and Sources of PM2.5 Chemical Components in Chengdu in Winter

Day-night PM2.5 samples were continuously collected in Chengdu from January 1 to 20, 2017, and the concentrations of major chemical components (water-soluble ions and carbonaceous components) were measured in the laboratory. During the observation period, the average mass concentration of PM2.5 was (127.1±59.9) μg·m-3. The mass concentration of water-soluble ions was (56.5±25.7) μg·m-3 and SO42-, NO3-, and NH4+ were the most dominant ions with a concentration of (13.6±5.5), (21.4±12.0), and (13.3±5.7) μg·m-3, respectively, accounting for 85.6% of the water-soluble ions. The average mass concentrations of organic carbon (OC) and elemental carbon (EC) were 34.0 and 6.1 μg·m-3, respectively, accounting for 26.8% and 4.8% of the PM2.5 mass concentration, respectively. The comparison of the average day-night concentration shows that the daytime and nighttime mass concentrations of PM2.5 are (120.4±56.4) and (133.8±64.0) μg·m-3, respectively, and that the nighttime pollution is more serious. The SO42-, NO3-, and NH4+ concentrations are higher during the day than at night, which is related to daytime light, which promotes the formation of secondary ions. The Cl-, K+, OC, and EC concentrations increase significantly, which may be affected by increased emissions from coal and material combustion. Based on the literature review and comparison of the winter chemical composition of PM2.5 in Chengdu in recent years, the SO42- concentration significantly decreases from 50.6 μg·m-3 in 2010 to 13.6 μg·m-3 in 2017. The NO3- concentration changes little; it is maintained at~20 μg·m-3. The analysis of the acid-alkali ion balance shows that PM2.5 in Chengdu is alkaline due to the relative overgrowth of NH4+, which is different from previous partially acidic results. The average value of NO3-/SO42- is 1.57. Mobile sources have a greater impact on the PM2.5 pollution in Chengdu in winter. The correlation coefficients of OC and EC between daytime and nighttime are 0.82 and 0.90, respectively (P<0.01), which indicates that the OC and EC sources are consistent. The SOC estimation shows that the SOC concentrations during the day and night are 8.5 μg·m-3 and 11.9 μg·m-3, respectively, accounting for 28.1% and 30.8% of the OC, respectively. The K+/EC average value is 0.31 and the correlation coefficient between K+ and OC is 0.87 (P<0.01), indicating that biomass combustion has a certain influence on the carbonaceous aerosol in Chengdu in winter. The principal component analysis shows that the winter PM2.5 in Chengdu mainly originates from combustion sources (coal burning, biomass burning, etc.), secondary inorganic sources, and soil and dust sources. The contribution rates are 32.8%, 34.5%, and 21.5%, respectively.

Concentrations and Size Distributions of Water-soluble Inorganic Ions in Aerosol Particles in Taiyuan, Shanxi

Size-resolved filter samples were collected in Taiyuan every other week from June 2012 to May 2014. The mass concentrations of water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO3- and SO42-) were measured by ion chromatography. The results showed that the total concentrations of measured water-soluble ions were (15.39±9.91), (21.10±15.49) and (36.34±18.51) μg·m-3 in PM1.1, PM2.1 and PM9, respectively. In PM1.1 and PM2.1, secondary water-soluble ions (SO42-, NO3- and NH4+) comprised 87.59% and 86.30% of all water-soluble ions, respectively, while in PM9, SO42- and Ca2+ comprised 32.78% and 28.54% of all water-soluble ions, respectively. SO42- and NH4+ had higher concentrations in winter and summer, and lower in spring and autumn. NO3-, K+and Cl- presented similar seasonal variation with a descending order of winter >autumn >spring >summer, and Ca2+ and Mg2+ followed the sequence of spring >winter >autumn >summer. SO42- and NH4+ showed a unimodal size distribution and the peak in the fine mode shifted from 0.43-0.65 μm in spring and autumn to 0.65-1.1 μm in summer. NO3- showed a bimodal size distribution. NO3- and NH4+ were dominated by the fine mode peaking at 0.43-2.1 μm in winter, and NO3- was dominated by the coarse mode peaking at 4.7-5.8 μm in summer. K+, Na+and Cl- also showed a bimodal size distribution with the fine mode at 0.43-1.1 μm and the coarse mode at 4.7-5.8 μm. Ca2+, Mg2+ and F- were unimodal with the peak in the coarse mode of 4.7-5.8 μm. On heavily polluted days, the mass concentrations of secondary water-soluble ions and Cl- accumulated, and secondary water-soluble ions were unimodal with the peak in the fine mode of 1.1-2.1 μm. However, on clear days, secondary water-soluble ions showed a bimodal size distribution with the fine mode at 0.43-0.65 μm and the coarse mode at 4.7-5.8 μm. The peak of secondary water-soluble ions in the fine mode shifted. PCA analysis showed that the sources of water-soluble ions were dominated by the secondary formation, coal combustion, industrial emission, biomass burning, and soil particles or falling dust.

The Water Soluble Ionic Composition of PM2.5 at 1,100 m-Highland of Mt. Hallasan on Jeju Island, Korea

The ambient mass concentration and chemical composition of the were determined at the highland site with 1,100 m above sea level on Jeju Island from June 2013 to November 2014. Yearly averaged mass concentration of was . concentrations were highest during the spring, while they tended to be lowest during the summer. Eight water soluble ionic species attributed 45.5% to mass. , and were major ions, which occupied to 27.9%, 3.7% and 12.3%, respectively. The greatest contributors to total mass concentration of water-soluble ions contained in were sulfate, ammonium and nitrate. These three ions accounted for 96.6% in total ions mass concentration of . We could infer that these three secondary ions exist mostly in the form of and . and had a good relationship and with r=0.9. The molar ratio of in this study was lower than the value observed in sea water and higher than that in soil dust, indicating that these two ions originated from other sources rather than ocean and soil dust in this study.

Chemical characteristics of size-resolved aerosols in winter in Beijing

Size-resolved aerosols were continuously collected by a Nano Sampler for 13days at an urban site in Beijing during winter 2012 to measure the chemical composition of ambient aerosol particles. Data collected by the Nano Sampler and an ACSM (Aerodyne Aerosol Chemical Speciation Monitor) were compared. Between the data sets, similar trends and strong correlations were observed, demonstrating the validity of the Nano Sampler. PM10 and PM2.5 concentrations during the measurement were 150.5±96.0μg/m3 (mean±standard variation) and 106.9±71.6μg/m3, respectively. The PM2.5/PM10 ratio was 0.70±0.10, indicating that PM2.5 dominated PM10. The aerosol size distributions showed that three size bins of 0.5–1, 1–2.5 and 2.5–10μm contributed 21.8%, 23.3% and 26.0% to the total mass concentration (TMC), respectively. OM (organic matter) and SIA (secondary ionic aerosol, mainly SO42−, NO3− and NH4+) were major components of PM2.5. Secondary compounds (SIA and secondary organic carbon) accounted for half of TMC (about 49.8%) in PM2.5, and suggested that secondary aerosols significantly contributed to the serious particulate matter pollution observed in winter. Coal burning, biomass combustion, vehicle emissions and SIA were found to be the main sources of PM2.5. Mass concentrations of water-soluble ions and undetected materials, as well as their fractions in TMC, strikingly increased with deteriorating particle pollution conditions, while OM and EC (elemental carbon) exhibited different variations, with mass concentrations slightly increasing but fractions in TMC decreasing.

Airborne submicron particulate (PM1) pollution in Shanghai, China: Chemical variability, formation/dissociation of associated semi-volatile components and the impacts on visibility

Hourly mass concentrations of water-soluble ions in PM1 and gasses (NH3, HNO3, HCl) were on-line measured with a Monitor for AeRosols and Gases Analyzer (MARGA) in Shanghai from Oct. 1 to Nov. 16, 2012. During the field campaign, 7 haze episodes (total 157h) were identified. 845h were identified as non-haze periods, excluding fog events and wet precipitation. The average mass concentration of PM1 and total water-soluble ions (TWSI) in PM1 in haze episodes were 78.9±29.9μg/m3 and 47.2±17.2μg/m3, 3.11 times (from 1.49 to 4.06 times) and 3.28 times (1.96 to 4.34 times) as those in non-haze periods, respectively. TWSI accounted for 60.4±18.8% of PM1 mass loading in the whole campaign. With the ascending PM1 mass concentration from 2.5 to 125.0μg/m3 from non-haze periods to haze episodes, average contribution of TWSI to PM1 mass loading decreased from 86.1% to 54.2%, while different species altered. Contribution of NO3− increased from 14.0% to 26.8%, while SO42− decreased from 39.5% to 15.0% and NH4+ remained around 13.7%. Relationship of visibility with PM1 and TWSI was addressed in specific RH ranges. It was found that hourly TWSI mass concentration showed better correlation with visibility. Formation/dissociation of semi-volatiles (NH4NO3 and NH4Cl) was also investigated and demonstrated. NH4NO3 and NH4Cl tended to partition into gas phase in non-haze periods. Particularly, strong dissociation from 11:00 LT to 17:00 LT was observed. In haze episodes, HNO3 and HCl tended to react with NH3 to form particulate matters. Interestingly, we found that formation/dissociation of NH4NO3 and NH4Cl exerted great impacts on visibility. Excluding the strong dissociation hours (11:00 LT to 17:00 LT) in correlation analysis of PM1 and visibility, correlation coefficients (R2) increased from 0.5762 to 0.7738 at RH<50%. No significant difference was observed in other RH ranges. In addition, Strong NH3 and HNO3 reaction resulted in the enhancement of NH4NO3 mass fraction, therefore increased associated water content in PM1 under high RH condition and contributed to visibility degradation.