Concentrations Of Water-soluble Ions Research Articles

Composition, sources and potential source regions of aerosols under contrasting environment conditions of Lanzhou, a valley city of western China: Observations by means of topographic relief

Chemical composition in PM2.5 (particulate matter with a diameter less than 2.5 μm) is essential information for evaluating their climate, environment and health effects. Concentrations of carbonaceous components and water-soluble ions in PM2.5 and the differences under varying environmental conditions in western China are poorly understood. During the period from July 2021 to July 2022, we conducted synchronous offline sampling of PM2.5 by deploying four identical sampling devices at altitudes ranging from 1500 m to 3600 m along the unique topography of the Lanzhou River Valley in western China. The major chemical components in PM2.5 are carbonaceous aerosols, NO3− and SO42− with the average concentrations of 28.07, 8.66 and 6.01 μg m−3 for the urban and surrounding rural areas, and 9.94, 2.45 and 3.11 μg m−3 for background site of Lanzhou. The concentrations of OC (organic carbon) and EC (elemental carbon) gradually decrease from urban area to suburban sites with increasing elevation. Coal combustion, vehicle emissions, secondary formation, salted aerosols and surface dust resuspension are found to be the primary sources of PM2.5 in both urban and rural areas of Lanzhou. The contribution of vehicle emissions decreases from urban areas to mountainous rural areas, contrary to the coal combustion and biomass burning. The study is significant for taking targeted measures to solve air pollution problem at different environmental conditions (urban, rural and background) over complex terrain.

Composition, characteristics, and treatment technologies of condensable particulate matter present in flue gas emitted by coking plants in China

To study the total particulate matter (TPM) in flue gas emitted by coking plants, a sampling system that could be used to collect filterable particulate matter (FPM) and condensable particulate matter (CPM) was designed and developed based on Method 202 recommended by the U.S. Environmental Protection Agency in 2017 and HJ 836-2017 issued by China. Using this system, FPM and CPM in flue gas emitted by four coking furnaces named A, B, C, and D were tested in China. Further, 9 water-soluble ions, 20 elements, and organic matter present in the CPM were simultaneously examined to determine their formation mechanisms. Statistical data suggested that the FPM emission level in the coking flue gas was low and the average mass concentration was less than 10 mg/m3. However, with high CPM and TPM emission levels, the TPM mass concentrations of A, B, C, and D were 130 ± 11.1, 84.4 ± 6.36, 35.1 ± 17.0, and 63.8 ± 13.0 mg/m3, respectively. The main component of TPM was CPM, and the average mass concentration of CPM accounted for 98%, 95%, 68%, and 95% of TPM in furnaces A, B, C, and D, respectively. Water-soluble ions were the important components of CPM, and the total concentration of water-soluble ions accounted for 70%, 87%, 42%, and 66% of CPM in furnaces A, B, C, and D, respectively. Toxic and harmful heavy metals, such as Mn, Cr, Ni, Cu, Zn, As, Cd, and Pb, were detected in CPM. The formation mechanism of CPM was analyzed in combination with flue-gas treatment. It was shown that the treatment process “activated carbon– flue-gas countercurrent-integrated purification technology + ammonia spraying” used in furnaces A and B was less effective in removing CPM, water-soluble ions, metals, and compounds than that of “selective catalytic reduction denitrification + limestone–gypsum wet desulfurization (spraying NaOH solution)” in furnaces C and D. Hence, different flue-gas treatment technologies and operation levels played vital roles in the formation, transformation, and removal of CPM from flue-gas. Organic components in CPM discharged from furnace A were determined via gas chromatography–mass spectrometry, and the top 15 organic components in CPM were obtained using the area normalization method. N-alkanes accounted for the highest proportion, followed by esters and phenols, and most of them were toxic and harmful to humans and ecosystems. Therefore, advanced CPM treatment technologies should be developed to reduce atmospheric PM2.5 and its precursors to improve ambient air quality in China.

Snow chemical characteristics and meteorological controlling factors from three snowfalls of Gande in the Tibetan plateau

Water-soluble ions (Cl−, SO42−, NO3−, Ca2+, Mg2+, Na+, K+ and NH4+) and trace elements (Pb, Cd, Cr and As) in snow samples were analyzed from three different snowfall events (Ⅰ, Ⅱ, Ⅲ) in December 2019 at Gande Meteorological Station, located in the southeastern part of the Tibetan Plateau region. From event Ⅰ to Ⅲ, the total concentration of water-soluble ions presented an increasing trend of 0.92, 1.43 and 3.01 mg L−1, respectively. The dominant cation was Ca2+ for all the events, while the dominate anion was SO42−, SO42− and Cl− in the event Ⅰ, Ⅱ and Ⅲ, respectively. Meteorological field and backward trajectory cluster analysis presented three different large-scale predominant wind directions of northwest wind, southwest wind and west wind for each event, revealing different transport processes and sources for snow components. The total concentration of water-soluble ions was mainly related to PM10 as the in-situ PM10 observation showed a similar increasing trend. The dominant trace element was different Pb, Cr and Pb in each event. The mixed source of crustal and industrial inputs was the key factor in three snowfalls, and its contribution was consistent with the concentration of dominant trace element. Herein, high fractions of Pb and Ca2+ were appeared in the event Ⅰ and Ⅲ, but largest proportion to Cr was enhanced in the event Ⅱ.

Preliminary Indications on an Atmospheric Particulate Matter and Rainwater Chemistry in Colombo, Sri Lanka: A Study During Southwestern Monsoon

The atmospheric cleansing nature of rainfall, specifically in the removal of particulate matter, is a determinant of rainwater quality. This study investigated the relationship between atmospheric particulate matter (PM10) concentration and rainwater quality in Colombo during the southwest monsoon period in 2023. The rainwater samples were collected using a manually prepared high- density polyethylene collector and analysed for pH, electrical conductivity (EC), water-soluble cations (Na+, K+, Ca2+, Mg2+, and NH4+), and anions (Cl-, NO3–, and SO42–). The concentration of atmospheric PM10 was obtained from the ambient air quality monitoring station (AQMS) at Battaramulla. The measured data were analysed using multivariate statistical techniques, including principal component analysis and Pearson correlation analysis, to identify relationships between the concentration of atmospheric PM10 and rainwater quality. The atmospheric PM10 showed an insignificant positive correlation with southwest monsoon rainfall (r=0.14, p>0.05). The concentration of atmospheric PM10 increased the total concentration of water-soluble ions (r=0.30) and decreased the pH (r=-0.42) and electrical conductivity (r=0.07) of rainwater samples. The concentration of Na+, K+ and Ca2+ displayed moderate positive correlation, while Mg2+, NH4+, Cl-,
 NO3- and SO42- showed a weak positive correlation of rainwater samples in the atmospheric PM10.
 This study contributes valuable insights into the variations of PM10 in the atmosphere and its potential implications on rainwater quality in southwest monsoon, underscoring the importance of comprehensive analyses for a more nuanced understanding of the intricate relationships between atmospheric components and rainwater chemistry.
 
 Keywords: Atmospheric chemistry, Correlation analysis, Particulate matter, Rainwater quality, Southwest monsoon

Shipboard Observations of Aerosol Chemical Properties Over the Western Pacific Ocean in Winter 2018

AbstractBased on a shipboard observation conducted in winter 2018, we reported the aerosol chemical properties and their differences in offshore and remote oceans over the Western Pacific Ocean (WPO). It's found that the chemical compositions over the WPO have significant spatial heterogeneity due to the influences of regional transport of anthropogenic aerosols and long‐path transport of dust aerosols. The average concentration of water soluble ions during the whole sampling period followed Cl− > OC > Na+ > > > Ca2+ > Mg2+ > EC > K+ > . Crustal elements of Ca (980.41 ng/m3), Na (971.55 ng/m3), and Al (781.16 ng/m3) were uniformly distributed in offshore area, but high proportion of Na elements dominated in remote regions. The total concentration of heavy metals including Zn, Cu, Cr, Pb and others originating from anthropogenic sources were 208 ng/m3 along the coastal region, about 10 times higher than that of 20.2 ng/m3 in the offshore and remote seas. For the reconstructed components, we found an increase of sea‐salt aerosol ranged from 3% to 72%, and a decrease of black carbon, organic matter and secondary inorganic salts, indicating a transformation from anthropogenic influence to marine environment. The rapidly increased secondary organic matter during dust event revealed that the transport of dust serves as catalysts to promote multi‐phase reactions. Cl− photochemical reaction rate in offshore area was mainly affected by sulfate from anthropogenic emissions, with an average chlorine loss rate of 18%, whereas it was inverse Cl− excess in the remote oceans.

Outdoor PM2.5 and their water-soluble ions in the Northern part of the Persian Gulf

Background: The environmental conditions potentially predispose the northern part of the Persian Gulf to the occurrence of dust storms. Outdoor PM2.5 and their water-soluble ions in Bushehr port were studied from December 2016 to September 2017. Methods: A total of 46 outdoor PM2.5 samples were collected by high-volume air sampler and eight water-soluble ions, including Ca2+, Mg2+, Na+, K+, F- , Cl- , NO3 - , and SO4 2- in PM2.5 were also measured by ion chromatography (IC). Results: The 24-hour average concentration of PM2.5 was in the range of 22.09 to 292.45 µg/m3 . The mean concentration of water-soluble ions in PM2.5 was in the range of 0.10±0.14 to 6.76±4.63 µg/m3 . The major water-soluble ions were the secondary inorganic aerosols (SO4 2- and NO3 - ), which accounted for nearly 41% of total water-soluble ions in PM2.5. The total water-soluble ions level of PM2.5 in winter was higher than that in spring and summer. The positive matrix factorization (PMF) model showed that the source contributions of PM2.5 were in the order of dust (55.8%), sea salt (17.1%), secondary sulfate (11.8%), industries (7%), vehicular emission (4.7%), and secondary nitrate (3.7%). Conclusion: According to the results, dust and sea salt are the main sources of water-soluble ions in PM2.5 in Bushehr port, which should attract much attention.

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.

Water-Soluble Ions and Heavy Metal Levels, Source Apportionment, and Health Risk of Indoor Dust in the Mogao Grottoes of Dunhuang, China

The direct ingestion of indoor dust particles at historical heritage sites is a primary exposure pathway for employees to heavy metals. Water-soluble ions (WSIs) and heavy metal levels, sources, bioaccessibility, and health risks associated with indoor dust in the Mogao Grottoes were analyzed using comprehensive methods to determine the differences in the concentrations and distribution characteristics of WSIs and heavy metals between statue dust and floor dust. The concentrations of WSIs and heavy metals and the magnetic values of χ lf and SIRM in indoor dust were higher than those in street dust and topsoil. The mean χ lf and SIRM of statue dust particles were 100.3 × 10 − 8 m 3 k g − 1 and 1686.9 × 1 0 − 5 Am 2 k g − 1 . Specifically, the concentration of Pb was 277 mg k g − 1 , 15-fold higher than the background value, indicating the continual receipt of heavy metals with high magnetic minerals during dust deposition. WSIs mainly originate from the weathering of surrounding rocks and earthen plaster; Pb originates from the shedding of paint of murals and sculptures; and Zn, Cu, and magnetic minerals originate from traffic sources. The bioaccessibility of heavy metals is high in the gastrointestinal phases of indoor dust. Overall, the health risks posed by heavy metals in indoor dust were low, with moderate to high risks in individual caves. Ingestion presents the highest noncarcinogenic and carcinogenic risk to employees. These results provide essential knowledge on indoor dust characteristics in the Mogao Grottoes, facilitating strategies for dust pollution mitigation and employee health risk control.

Characteristics and Source Apportionment of PM2.5 in the Core Area of Ili River Valley in Spring

To explore the characteristics and sources of PM2.5 in the core area of Ili River Valley in spring, a total of 140 PM2.5 samples were collected at six sampling sites during April 20-29, 2021, and 51 chemical components including inorganic elements, water-soluble ions, and carbon components were analyzed. The results showed that ρ(PM2.5) was at a low level during sampling, ranging from 9 μg·m-3 to 35 μg·m-3. Si, Ca, Al, Na, Mg, Fe, and K were the most abundant elements, accounting for 12% of PM2.5, indicating that PM2.5 was affected by the dust sources in spring. The spatial distribution characteristics of elements depended on the surrounding environments of the sampling sites. The new government area was affected by coal-fired sources, so the value of As concentration was high. Yining Municipal Bureau and the Second Water Plant were greatly affected by motor vehicle sources, so the values of Sb and Sn concentration were higher. The enrichment factor results showed that Zn, Ni, Cr, Pb, Cu, and As were mainly emitted from fossil fuel combustion and motor vehicles. The concentration of water-soluble ions accounted for 33.2% of PM2.5. Among them, ρ(SO42-), ρ(NO3-), ρ(Ca2+), and ρ(NH4+) were (2.48±0.57), (1.22±0.75), (1.18±0.49), and (0.98±0.45) μg·m-3, respectively. The higher Ca2+ concentration also reflected the contribution of dust sources. The ratio of n(NO3-)/n(SO42-) was between 0.63 and 0.85, which indicated that the influence of stationary sources was more important than that of mobile sources. Both Yining Municipal Bureau and the Second Water Plant were affected by motor vehicle exhaust; therefore, their n(NO3-)/n(SO42-) ratios were high. Yining County was in a residential area, and therefore its n(NO3-)/n(SO42-) ratio was lower. The average ρ(OC) and ρ(EC) in PM2.5 were 5.12 μg·m-3(4.67-6.25 μg·m-3) and 0.75 μg·m-3(0.51-0.97 μg·m-3), respectively. Yining Municipal Bureau was significantly affected by motor vehicle exhaust from both sides, so the values of OC and EC concentration were slightly higher than those in other sampling sites. The SOC concentration was calculated by the minimum ratio method, and the results showed that the values of SOC concentration in the New Government Area, the Second Water Plant, and Yining Ecological Environment Bureau were higher than those in other sampling sites. The results of the CMB model showed that PM2.5 in this area mainly came from the contribution of secondary particulate matter and dust sources, which accounted for 33.3% and 17.5%, respectively. Secondary organic carbon (16.2%) was the main contribution source of secondary particulate matter.

Observational evidence for the non-suppression effect of atmospheric chemical modification on the ice nucleation activity of East Asian dust

Airborne mineral dust triggers ice formation in clouds and alters cloud microphysical properties by acting as ice-nucleating particles (INPs), potentially influencing weather and climate at regional and global scales. Anthropogenic pollution would modify natural mineral dust during the atmospheric transport process. However, the effects of anthropogenic pollution aging on the ice nucleation activity (INA) of mineral dust remain not well-understood. In this study, we investigated the immersion mode ice nucleation properties and particle chemical characterizations of collected size-resolved Asian dust samples (eight particle size classes ranging from 0.18 to 10.0 μm), and testified the chemical modification of aged dust particles via particle chemistry and morphology analyses including the mass concentrations of particulate matter, the water-soluble ion concentrations, the mental element concentrations, and single-particle morphology. The mass fraction of Ca2+ in element Ca and the mean relative mass proportions of supermicron Ca2+ increased by 67.0 % and 3.5–11.2 % in aged Asian dust particles, respectively, suggesting the occurrence of heterogeneous reactions. On the other hand, the total INP concentrations (total NINP) and total ice nucleation active site densities (total ns(T)) were consistent between aged and normal dust particles (0.62–1.18 times) without a statistically significant difference. And the NINP and ns(T) of chemically aged supermicron dust (1.0–10.0 μm) in each particle size class were nearly equal to or slightly higher than those of normal Asian dust, which were 0.70–2.45 times and 0.64–4.34 times at −18 °C, respectively. These results reveal that anthropogenic air pollution does not notably change the INP concentrations and does not impair the INA of Asian dust. Our work provides direct observational evidence and clarifies the non-suppression effect of anthropogenic air pollution on the INA of East Asian dust, advancing the understanding of the ice nucleation of airborne aged mineral dust.

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.

Concentrations of aerosol water-soluble ions(WSI)with high-time-resolution observation over Antarctic Ocean

Concentrations of aerosol water-soluble ions(WSI)with high-time-resolution observation over Antarctic Ocean

Ambient particle composition and toxicity in 31 major cities in China

Current assessment of air quality or control effectiveness is solely based on particulate matter (PM) mass levels, without considering their toxicity differences in terms of health benefits. Here, we collected a total of 465 automobile air conditioning filters from 31 major Chinese cities to study the composition and toxicity of PM at a national scale. Dithiothreitol assay showed that normalized PM toxicity (NIOG) in different Chinese cities varied greatly from the highest 4.99 × 10−3 for Changsha to the lowest 7.72 × 10−4 for Yinchuan. NIOG values were observed to have significant correlations with annual PM10 concentration (r = -0.416, p = 0.020) and some PM components (total fungi, SO42− and calcium element). The concentrations of different elements and water-soluble ions in PM also varied by several orders of magnitude for 31 cities in China. Endotoxin concentrations in PM analyzed using limulus amebocyte lysate assay ranged from 2.88 EU/mg PM (Hangzhou) to 62.82 EU/mg PM (Shijiazhuang) among 31 Chinese cities. Besides, real-time qPCR revealed 10∼100-fold differences in total bacterial and fungal levels among 31 Chinese cities. The concentrations of chemical (water soluble ions and trace elements) and biological (fungi, bacteria and endotoxin) components in PM were found to be significantly correlated with some meteorological factors and gaseous pollutants such as SO2. Our results have demonstrated that PM toxicity from 31 major cities varied greatly up to 6.5 times difference; and components such as fungi and SO42− in PM could play important roles in the observed PM toxicity. The city-specific air pollution control strategy that integrates toxicity factors should be enacted in order to maximize health and economic co-benefits. This work also provides a comprehensive view on the overall PM pollution situation in China.

Secondary inorganic aerosol chemistry and its impact on atmospheric visibility over an ammonia-rich urban area in Central Taiwan

This study investigated the hourly inorganic aerosol chemistry and its impact on atmospheric visibility over an urban area in Central Taiwan, by relying on measurements of aerosol light extinction, inorganic gases, and PM2.5 water-soluble ions (WSIs), and simulations from a thermodynamic equilibrium model. On average, the sulfate (SO42−), nitrate (NO3−), and ammonium (NH4+) components (SNA) contributed ∼90% of WSI concentrations, which in turn made up about 50% of the PM2.5 mass. During the entire observation period, PM2.5 and SNA concentrations, aerosol pH, aerosol liquid water content (ALWC), and sulfur and nitrogen conversion ratios all increased with decreasing visibility. In particular, the NO3− contribution to PM2.5 increased, whereas the SO42− contribution decreased, with decreasing visibility. The diurnal variations of the above parameters indicate that the interaction and likely mutual promotion between NO3− and ALWC enhanced the hygroscopicity and aqueous-phase reactions conducive for NO3− formation, thus led to severely impaired visibility. The high relative humidity (RH) at the study area (average 70.7%) was a necessary but not sole factor leading to enhanced NO3− formation, which was more directly associated with elevated ALWC and aerosol pH. Simulations from the thermodynamic model depict that the inorganic aerosol system in the study area was characterized by fully neutralized SO42− (i.e. a saturated factor in visibility reduction) and excess NH4+ amidst a NH3-rich environment. As a result, PM2.5 composition was most sensitive to gas-phase HNO3, and hence NOx, and relatively insensitive to NH3. Consequently, a reduction of NOx would result in instantaneous cuts of NO3−, PM2.5, and ALWC, and hence improved visibility. On the other hand, a substantial amount of NH3 reduction (>70%) would be required to lower the aerosol pH, driving more than 50% of the particulate phase NO3− to the gas phase, thereby making NH3 a limiting factor in shifting PM2.5 composition.

Spatial distributions of salt-based ions, a case study from the Hunshandake Sandy Land, China.

Soil water soluble base ion salt-based ion concentrations are critical parameters for estimating soil buffer capacity and vegetation productivity. Ionic content clearly covaries with the distribution of plant communities. Previous studies on salt-based ions in soils focused primarily on ion migration and its relationships with vegetation growth. Few studies have sought to characterize larger scale spatial distribution of salt-based ions or correlation with climatic and plant community characteristics. This study used ion chromatography to analyze the salt-based ion content (Ca2+, Mg2+, Na+ and K+) of surface soils from the Hunshandake sandy lands. Statistical methods were used interpret spatial variation. Results showed that the average content of salt-based ions in Hunshandake sandy land was 86.57 mg/kg. Average values ranked as Ca2+ > Na+ > K+ > Mg2+ but concentrations also exhibited uneven spatial distributions. Horizontal spatial variation in Ca2+, Mg2+ and Na+ ions showed these ions gradually decrease from northwest to southeast. Potassium ions (K+) showed no obvious spatial variation trends. Ions varied significantly across different soil layers but their average concentrations ranked as K+>Na+>Ca2+>Mg2+ (from shallow to deep). The 20–30 cm soil layer contained the highest salt ion concentrations. Of the four base ions, only K+ ions appeared in surface samples. In terms of water soluble base ion available salt-based ions, Ca2+ occurred in the highest concentrations along the north and west side of the study area. K+ ions occurred in the highest concentrations along the south and east sides of the study area. Na+ concentrations did not show a consistent spatial pattern. Statistical analysis detected significant correlations of normalized ion concentration parameters (Ca2+/CECT, K+/CEC, effective water soluble base ion salt-based ions) and the total species number, average species number and total biomass of the plant communities (P <0.05). This study can help inform understanding of soil water transport in sandy areas and provide a reference for interpreting ecosystems in arid regions.

Metals, PAHs and oxidative potential of size-segregated particulate matter and inhalational carcinogenic risk of cooking at a typical university canteen in Shanghai, China

Cooking is an important source of indoor emissions, and exposure to cooking emissions can instigate adverse health effects. Oxidative potential (OP) is a good indicator for assessing health risk, but studies detecting the OP of cooking emissions are rare. In this paper, size-segregated samples were collected at four sites in the canteen to study the chemical characteristics and OP of particulate matter (PM) emitted from cooking. The four sites were set to study the effects of different cooking styles and kitchen types. The results showed that the concentrations of most metals, water-soluble ions, PAHs, and OP at four sites followed the trend: deep-frying > stir-frying > second floor hall > first floor hall. And the concentration at the fine fraction (PM0.056-3.2) was much higher than that at coarse fraction (PM3.2-18). The PM OP at four sites were 1.1642 nmol m−3·min−1, 1.2088 nmol m−3·min−1, 0.8589 nmol m−3·min−1 and 0.9507 nmol m−3·min−1, respectively. The correlation between OP and other components showed that Zn (|r| = 0.444) and DBA (|r| = 0.507) were moderately related to OP, which suggested that heavy metals and PAHs might be contributed to PM OP. The carcinogenic risk assessments of heavy metals and PAHs showed that, there might be an increasing of potential carcinogenic risk if exposure to cooking environment for lifetime. Our results were firstly helpful for PM characteristics researches on cooking emissions, and also significant to public health protection, especially for people who usually cook.

Understanding aerosol composition in a tropical inter-Andean valley impacted by agro-industrial and urban emissions

Abstract. Agro-industrial areas are frequently affected by various sources of atmospheric pollutants that have a negative impact on public health and ecosystems. However, air quality in these areas is infrequently monitored because of their smaller population compared to large cities, especially in developing countries. The Cauca River valley (CRV) is an agro-industrial region in southwestern Colombia, where a large fraction of the area is devoted to sugarcane and livestock production. The CRV is also affected by road traffic and industrial emissions. This study aims to elucidate the chemical composition of particulate matter fine mode (PM2.5) and to identify the main pollutant sources before source attribution. A sampling campaign was carried out at a representative site in the CRV region, where daily averaged mass concentrations of PM2.5 and the concentrations of water-soluble ions, trace metals, organic and elemental carbon, and various fractions of organic compounds (carbohydrates, n alkanes, and polycyclic aromatic hydrocarbons – PAHs) were measured. The mean PM2.5 was 14.4±4.4 µg m−3, and the most abundant constituent was organic material (52.7 % ± 18.4 %), followed by sulfate (12.7 % ± 2.8 %), and elemental carbon (7.1 % ± 2.5 %), which indicates the presence of secondary aerosol formation and incomplete combustion. Levoglucosan was present in all samples, with a mean concentration of (113.8±147.2 ng m−3), revealing biomass burning as a persistent source. Mass closure using the elemental carbon (EC) tracer method explained 88.4 % on PM2.5, whereas the organic tracer method explained 70.9 % of PM2.5. We attribute this difference to the lack of information of specific organic tracers for some sources, both primary and secondary. Organic material and inorganic ions were the dominant groups of species (79 % of PM2.5). OMprim and OMsec contribute 24.2 % and 28.5 % to PM2.5. Inorganic ions as sulfate, nitrate, and ammonia constitute 19.0 %, EC 7.1 %, dust 3.5%, particle-bounded water (PBW) 5.3 %, and trace element oxides (TEOs), 0.9 % of PM2.5. The aerosol was acidic, with a pH of 2.5±0.4, mainly because of the abundance of organic and sulfur compounds. Diagnostic ratios and tracer concentrations indicate that most PM2.5 was emitted locally and had contributions of both pyrogenic and petrogenic sources, that biomass burning was ubiquitous during the sampling period and was the main source of PAHs, and that the relatively low PM2.5 concentrations and mutagenic potentials are consistent with low-intensity, year-long biomass burning (BB) and sugarcane pre-harvest burning in the CRV.

Chemical characterization of water-soluble ions in highly time-resolved atmospheric fine particles in Istanbul megacity.

The diurnal and seasonal variations of water-soluble ions (WSIs) in fine particles were investigated in an area predominantly affected by traffic emissions in Beşiktaş, Istanbul between 2017 and 2018. PM2.5 samples were collected at high time resolutions of 2 h during the daytime and 12 h during the nighttime for six sampling campaigns over all seasons. Five inorganic water-soluble ions (SO42-, NH4+, NO3-, PO4-3, and NO2-) were determined using ion chromatography. Source analysis was investigated with principal component analysis (PCA) and bivariate polar plots. In descending order, WSIs concentrations were SO42->NH4+> NO3-> PO4-3>NO2- during the different seasons. The high time-resolved concentrations ranged as follows: sulfate 1.2-1118.1, ammonium 0.3-289.9, phosphate 2.9-107.6, nitrate 4.6-179.7, and nitrite 0.8-9.0 ng/m3, with yearly averages of 226.5, 59.0, 58.4, 37.9, and 3.3 ng/m3, respectively. Except for phosphate, all WSIs had strong seasonal variations with high concentrations during the winter and low concentrations during the summer. Molar ratios revealed that the formation of ammonium sulfate was less likely than ammonium nitrate. Principal component analysis resolved secondary aerosols (43.9%), residential heating (34.6%), shipping emissions (8.7%), and vehicle emissions (6.7%) as the major sources of WSIs, OC, EC, and PM2.5 in Beşiktaş, Istanbul. Sulfate aerosol originated mainly from two nearby areas, SW and NE, of the sampling site tentatively due to residential heating and shipping emissions, respectively.

Combustion related ammonia promotes PM2.5 accumulation in autumn in Tianjin, China

Ammonium (NH4+) is one of the most important inorganic components in PM2.5, and plays key roles in increasing the concentration of PM2.5. Understanding the sources and formation processes of NH4+ is an effective way to control PM2.5. In this study, daily PM2.5 samples were collected from September 01 to November 30, 2017 in Tianjin, and water-soluble ion concentrations and δ15N-NH4+ in PM2.5 were analyzed. The results showed that (NH4)2SO4 and NH4NO3 were the major chemical forms of NH4+. In particular, NH4NO3 dominated the liquid water content (ALWC) increase on haze days, leading to more NH3 partitioning into the particle phase, and this formation mechanism of NH4NO3 might be self-amplified with an increase in ALWC concentrations. The mean values of δ15N-NH4+ were 14.7 ± 5.2‰, and the estimated initial ambient δ15N-NH3 was −15.6 ± 9.3‰. The mean fractional contributions of volatilization sources, fossil fuel-related sources and biomass burning were 31.9 ± 15.8%, 45.9 ± 12.6% and 22.2 ± 18.3%, respectively, which were estimated by the stable isotope mixing model. Obviously, the NH3 related to combustion emissions (68.1 ± 15.9%) dominated the source of aerosol NH4+ during autumn in Tianjin in this study. We also found that the fractional contributions of these sources have varied during different pollution periods, and the contributions of biomass burning emissions increased to 60% on haze days in November. Our results highlight that fossil fuel related source emissions of NH3 dominate the formation of NH4NO3 in autumn, leading to the occurrence of haze in autumn in Tianjin. Nevertheless, the biomass burning emissions were non-ignorable.

The optical properties and in-situ observational evidence for the formation of brown carbon in clouds

Abstract. Atmospheric brown carbon (BrC) makes a substantial contribution to aerosol light absorption and thus global radiative forcing. Although BrC may change the lifetime of the clouds and ultimately affect precipitation, little is known regarding the optical properties and formation of BrC in the clouds. In the present study, the light-absorption properties of cloud droplet residual (cloud RES) were measured by coupled a ground-based counterflow virtual impactor (GCVI) and an aethalometer (AE-33), in addition to the cloud interstitial (cloud INT) and ambient (cloud-free) particles by PM2.5 inlet-AE-33 at Mt. Tianjing (1690 m a.s.l.), a remote mountain site in southern China, from November to December 2020. Meanwhile, the light-absorption and fluorescence properties of water-soluble organic carbon (WSOC) in the collected cloud water and PM2.5 samples were also obtained, associated with the concentration of water-soluble ions. The mean light-absorption coefficient (Abs370) of the cloud RES, cloud INT, and cloud-free particles were 0.25 ± 0.15, 1.16 ± 1.14, and 1.47 ± 1.23 Mm−1, respectively. The Abs365 of WSOC was 0.11 ± 0.08 Mm−1 in cloud water and 0.40 ± 0.31 Mm−1 in PM2.5, and the corresponding mass absorption efficiency (MAE365) was 0.17 ± 0.07 and 0.31 ± 0.21 m2 g−1, respectively. A comparison of the light-absorption coefficient between BrC in cloud RES and cloud INT particles, and WSOC in cloud water and PM2.5 indicates a considerable contribution (48 %–75 %) of water-insoluble BrC to total BrC light absorption. Secondary BrC estimated by minimum R squared (MRS) method dominated the total BrC in cloud RES (67 %–85 %), rather than in the cloud-free (11 %–16 %) and cloud INT (9 %–23 %) particles. It may indicate the formation of secondary BrC during cloud processing. Supporting evidence includes the enhanced WSOC and dominant contribution of the secondary formation and biomass burning factor (&gt;80 %) to Abs365 in cloud water provided by positive matrix factorization (PMF) analysis. In addition, we showed that the light absorption of BrC in cloud water was closely related to humic-like substances and tyrosine-like and/or protein-like substances (r&gt;0.63, p&lt;0.01), whereas only humic-like substances for PM2.5, as identified by excitation-emission matrix fluorescence spectroscopy.