Study on the phase transformation mechanism and influencing factors of inorganic condensable particulate matter from coal-fired power plants.

In this study, the concentration of inorganic ions (SO42-, NH4+, NO3- and NO2-) and morphological characteristics of condensable particulate matter (CPM) were investigated to elucidate the formation mechanism of inorganic CPM from ultra-low emission coal-fired power plants. The concentration of inorganic ions increased with the increase of H2O content and concentration of inorganic gaseous contaminants (SO2, NOX and NH3), and decrease of condensation temperature, indicating the enhancement of heterogenous reaction in the saturated flue gas. Furthermore, NOX and SO2 could undergo redox reactions, leading to an elevation in the concentration of SO42- and NO3-. Additionally, the introduction of NH3 resulted in increased concentrations of SO42-, NO3-, and NO2-, highlighting the significant role of NH3 neutralization in CPM nucleation. The condensation of SO3/sulfuric acid aerosols was enhanced under saturation conditions, and SO2 and SO3/sulfuric acid aerosols could contribute synergistically to the formation of SO42-. Moreover, morphological analysis revealed the presence of both well-aggregated solid CPM and dispersed liquid CPM, confirming the formation of inorganic CPM during fast condensation. Furthermore, the detected CPM were composed of S and O, which identified the significant role of sulfates in the inorganic CPM. These findings provide valuable insights for the control of inorganic CPM in flue gas systems.

[Water-soluble Inorganic Ion Content of PM2.5 and Its Change Characteristics in Urban Area of Beijing in 2022].

To explore the content and variation characteristics of water-soluble ions of atmospheric fine particles (PM2.5) in a Beijing urban area and put forward the pollution prevention and control scheme, the water-soluble ions, gaseous precursors (SO2, NO2), and meteorological factors (temperature, RH) of PM2.5 in 2022 were analyzed and determined. The results showed that the water-soluble ions with the highest proportion in PM2.5 in the Beijing City urban area were NO3-, NH4+, and SO42-, accounting for 52.7% of PM2.5. The mass concentrations of PM2.5 and SNA were lower than the historical results, whereas the proportion of SNA, SOR, and NOR was higher than the historical results. This showed that the fine particulate matter pollution in Beijing has been significantly improved, but it still has strong secondary pollution characteristics. NO3-/SO42-(2.2) was higher than those of historical and nearby provinces and cities, reflecting the expanding influence of mobile sources. In terms of seasonal variation, PM2.5 showed the characteristic of high in autumn and low in summer. The proportion of NO3- was the highest in autumn, spring, and winter; the proportion of SO42- was the highest in summer; and the proportion of NH4+ changed little in each season. The seasonal variation rules of NOR and SOR were almost opposite, which reflected the difference in transformation factors between NOR and SOR. The main forms of SNA in the Beijing urban area were NH4NO3 and (NH4)2SO4. The neutralization degree of cations and anions was the highest in winter, the cation NH4+ was slightly insufficient in summer, and NH4+ was in excess in spring and autumn. The Beijing urban area was an ammonia-rich environment. In terms of pollution level, RH, particulate matter moisture, and water-soluble ions mass concentration all increased with the increase in pollution level, and SNA increased fastest, with its proportion in PM2.5 increasing first and then stabilizing, whereas the contribution rate of other water-soluble ions decreased gradually. In terms of spatial distribution, the mass concentration relationship of SNA at the central urban area and suburbs was NO3- > SO42- > NH4+, which reflected the pollution characteristics dominated by NO3-. The highest contribution rate of SNA to PM2.5 occurred in the eastern region, the central urban area, and the transmission point, indicating that the secondary reaction was relatively active in the central urban area and the eastern region, and the regional transport was also an important source of secondary ions.

Chemical characterization and source apportionment of PM2.5 in a Northeastern China city during the epidemic period.

To investigate the influence of COVID-19 lockdown measures on PM2.5 and its chemical components in Shenyang, PM2.5 samples were continuously collected from January 1 to May 31, 2020. The samples were then analyzed for water-soluble inorganic ions, metal elements, organic carbon, and elemental carbon. The findings indicated a significant decrease in PM2.5 and its various chemical components during the lockdown period, compared to pre-lockdown levels (p < 0.05), suggesting a substantial improvement in air quality. Water-soluble inorganic ions (WSIIs) were identified as the primary contributors to PM2.5, accounting for 47% before the lockdown, 46% during the lockdown, and 37% after the lockdown. Ionic balance analysis revealed that PM2.5 exhibited neutral, weakly alkaline, and alkaline characteristics before, during, and after the lockdown, respectively. NH4+ was identified as the main balancing cation and was predominantly present in the form of NH4NO3 in the absence of complete neutralization of SO42- and NO3-. Moreover, the higher sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR), along with the significant increase in PM2.5/EC, suggested intense secondary transformation during the lockdown period. The elevated OC/EC ratio during the lockdown period implied higher secondary organic carbon (SOC), and the notable increase in SOC/EC ratio indicated a significant secondary transformation of total carbon. The enrichment factor (EF) results revealed that during the lockdown, 9 metal elements (As, Sn, Pb, Zn, Cu, Sb, Ag, Cd, and Se) were substantially impacted by anthropogenic emissions. Source analysis of PMF was employed to identify the sources of PM2.5 in Shenyang during the study period, and the analysis identified six factors: secondary sulfate and vehicle emissions, catering fume sources, secondary nitrate and coal combustion emissions, dust sources, biomass combustion, and industrial emissions, with secondary sulfate and vehicle emissions and catering fume sources contributing the most to PM2.5.

Mapping nationwide concentrations of sulfate and nitrate in ambient PM2.5 in South Korea using machine learning with ground observation data.

Particulate matter (PM) is a major air pollutant in Northeast Asia, with frequent high PM episodes. To investigate the nationwide spatial distribution maps of PM2.5 and secondary inorganic aerosols in South Korea, prediction models for mapping SO42- and NO3- concentrations in PM2.5 were developed using machine learning with ground-based observation data. Specifically, the random forest algorithm was used in this study to predict the SO42- and NO3- concentrations at 548 air quality monitoring stations located within the representative radii of eight intensive air quality monitoring stations. The average concentrations of PM2.5, SO42-, and NO3- across the entire nation were 17.2 ± 2.8, 3.0 ± 0.6, and 3.4 ± 1.2 µg/m3, respectively. The spatial distributions of SO42- and NO3- concentrations in 2021 revealed elevated concentrations in both the western and central regions of South Korea. This result suggests that SO42- concentrations were primarily influenced by industrial activities rather than vehicle emissions, whereas NO3- concentrations were more associated with vehicle emissions. During a high PM2.5 event (November 19-21, 2021), the concentration of SO42- was primarily influenced by SOX emissions from China, while the concentration of NO3- was affected by NOX emissions from both China and Korea. The methodology developed in this study can be used to explore the chemical characteristics of PM2.5 with high spatiotemporal resolution. It can also provide valuable insights for the nationwide mitigation of secondary PM2.5 pollution.

[Pollution Characteristics, Source Apportionment, and Meteorological Response of Water-soluble Ions in PM2.5 in Xinxiang, North China].

Pollution variation, source characteristics, and meteorological effects of water-soluble inorganic ions (WSIIs) in PM2.5 were analyzed in Xinxiang city, Henan Province. PM2.5 samples and their chemical components were monitored online by using URG-9000 in four seasons:winter (January, 2022), spring (April, 2022), summer (July, 2022), and fall (October, 2022). The results showed that the TWSIIs had the same seasonal fluctuations as PM2.5. The average seasonal concentrations of WSIIs ranged from 19.62-72.15 µg·m-3, accounting for more than 60% of PM2.5, demonstrating that WSIIs were the major components of PM2.5. The annual concentration value of NO3-/SO42- was 2.11, which showed an increasing trend, suggesting predominantly mobile sources for secondary inorganic aerosols (SNA). Further, the molar concentration value [NH4+]/[NO3-] was 1.95, demonstrating that agriculture emissions were the dominant contributors to atmospheric nitrogen. Furthermore, the backward trajectory analysis showed that the concentrations of Ca2+ and Mg2+ were higher when the northeasterly wind prevailed and the wind speed was high. High values of SOR and NOR were correlated with low temperatures and high relative humidity (T < 8℃, RH > 60%), demonstrating that more gaseous precursors were converted into sulfate and nitrate. At high temperatures (T > 24℃), there was no apparent high NOR value like that for SOR, mainly due to the decomposition of NH4NO3 at high temperatures. Finally, backward trajectories associated with the PMF-resolved results were used to explore the regional transport characteristics. The results illustrated that dust sources in the study areas were mainly influenced by air trajectories originating from the northwest regions, whereas secondary sulfate, secondary nitrate, and biomass sources contributed more to WSIIs when wind speed and altitude air masses were low in the area surrounding the observation site.

Grape cultivars adapted to hotter, drier growing regions exhibit greater photosynthesis in hot conditions despite less drought-resistant leaves.

BACKGROUND AND AIMS: Many agricultural areas are expected to face hotter, drier conditions from climate change. Understanding the mechanisms that crops use to mitigate these stresses can guide breeding for more tolerant plant material. We tested relationships between traits, physiological function in hot conditions and historical climate associations to evaluate these mechanisms for winegrapes. We expected a more negative leaf osmotic potential at full hydration (πo), which reduces leaf turgor loss during drought, and either a metabolically cheaper or more osmoprotectant leaf chemical composition, to allow cultivars associated with hot, dry regions to maintain greater gas exchange in hot growing conditions. METHODS: We measured πo, gas exchange and leaf chemistry for seven commercially important winegrape cultivars that vary widely in historical climate associations. Vines were grown in common-garden field conditions in a hot wine-growing region (Davis, CA, USA) and measured over the hottest period of the growing season (July-September). KEY RESULTS: The value of πo varied significantly between cultivars, and all cultivars significantly reduced πo (osmotically adjusted) over the study period, although osmotic adjustment did not vary across cultivars. The value of πo was correlated with gas exchange and climate associations, but in the direction opposite to expected. Photosynthesis and πo were higher in the cultivars associated with hotter, less humid regions. Leaf chemical composition varied between cultivars but was not related to climate associations. CONCLUSIONS: These findings suggest that maintenance of leaf turgor is not a primary limitation on grapevine adaptation to hot or atmospherically dry growing conditions. Thus, selecting for a more negative πo or greater osmotic adjustment is not a promising strategy to develop more climate-resilient grape varieties, contrary to findings for other crops. Future work is needed to identify the mechanisms increasing photosynthesis in the cultivars associated with hot, dry regions.

Source apportionment of fine aerosol particles of water-soluble and carbonaceous species measured in semi-urban (Kharagpur) and megacity (Kolkata) atmospheres over the eastern Indo-Gangetic plain: Chemical characterisation, relative abundance and anthropogenic contributions.

We conducted the source apportionment of fine aerosol particles (aerodynamic diameter ≤1.6µm) collected with the indigenously designed-fabricated submicron aerosol sampler (SAS) in the eastern Indo-Gangetic plain (IGP) semi-urban (Kharagpur, KGP) and megacity (Kolkata, KOL) atmospheres, examining the chemical characteristics at KGP (January 2015-February 2016), and accentuating their abundance and the sources of anthropogenic pollution relative to KOL. The fine water-soluble inorganic ions (WSII) at KGP predominantly constituted Ca2+ (52 %) and equivalent amounts (12 % each) of Cl-, Mg2+ and secondary inorganic aerosols (sum of SO42-, NO3- and NH4+). The annual mean of SO42- at KGP was twice (thrice) larger than NO3- (NH4+); this of organic carbon (OC) was thrice elemental carbon (EC), with secondary OC being 37 % of the total OC. The concordance in peaks of OC with K+ concentrations was identified during the seasonal open biomass burning at KGP (November and May). While the annual mean of OC (EC) concentration at KGP was slightly lower than (nearly equivalent to) KOL; K+, NO3-, NH4+ and F- concentrations at KOL were twice larger than KGP. Source quantification using Positive Matrix Factorization (PMF) revealed the regional dust with crustal elements marked as clean (polluted) at KGP (KOL) constituted the largest fractional contribution among the six identified factors at both KGP and KOL. The combustion-derived anthropogenic pollution comprising about 60 % (50 %) of fine particles at KOL (KGP) was predominantly from the transportation sector (in vehicular emissions and regional dust), coal combustion (industries) and open biomass burning at KOL; it was from brick kilns, residential biofuel combustion, and open biomass burning at KGP. The source-wide distribution of measured aerosol species showed their emergence from largely different sources at KGP and KOL; thereby suggesting a prioritised strategy for sustainable emissions mitigation considering the prominent sources of combustion-derived anthropogenic pollution and aerosol species for megacity and semi-urban atmospheres.

Determination of inorganic ions and carbohydrates in cardioplegia and nephroplegia solutions by ion chromatography.

In this study, methods for analyzing inorganic ions and carbohydrates in cardioplegia and nephroplegia solutions were developed and validated using ion chromatography with both conductivity and pulsed amperometric detection. The inorganic ions such as sodium, potassium, and calcium were separated by a cation-exchange column with 27 mM methanesulfonic acid as mobile phase at 0.5 mL/min. The anion (chloride) and carbohydrates (mannitol and glucose) were analyzed by an anion-exchange column using a mobile phase of 20 mM sodium hydroxide at 1.0 mL/min. The methods showed a high sensitivity for all analytes, with quantification limits from 0.0002 to 0.06 mg/L. Good linearities between the peak areas and concentrations were found for all analytes within the selected concentration range (R2  > 0.999). Relative standard deviation values for repeatability and interday precision were 0.1%-1.0% and 0.7%-1.6%, respectively. The accuracy was validated by determining the percentage recovery, which was between 98.0% and 101.3% for all analytes, indicating good accuracy of the methods. The robustness was verified by using an experimental design. Finally, real samples were analyzed to determine the content of the analytes. All assay values were between 96.8% and 102.5%.

Chemical characteristics, distribution patterns, and source apportionment of particulate elements and inorganic ions in snowpack in Harbin, China.

Snowpack, which serves as a natural archive of atmospheric deposition of multiple pollutants, is a practical environmental media that can be used for assessing atmospheric records and input of the pollutants to the surface environments and ecosystems. A total of 29 snowpack samples were collected at 20 sampling sites covering three different functional areas of a major city (Harbin) in Northeast China. Two samples at the "snow layer" and one or two samples at the "particulate layer" were collected at each sampling site in the industrial areas characterized by multi-layer snowpack, and only one sample at the "snow layer" was collected at each sampling site in the cultural and recreational as well as agricultural areas. The snow contents of 31 elements (Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Y, Cd, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Pb) and six major water-soluble inorganic ions (WSIIs, NH4+, K+, Ca2+, NO2-, NO3-, and SO42-) were analyzed. The total mass of the measured elements is dominated (95.8%-99.2%) by crustal elements. Heavy metals only account for 0.77%-4.07% of the total mass of the elements, but are occasionally close to or even above the standard limit in the "Environmental Quality Standards for Surface Water" of China (GB3838-2002). SO42- and Ca2+ are the main anion and cation, accounting for 34.9%-81.1% and 1.43%-29.9%, respectively, of the measured total ions. Total atmospheric deposition of crustal elements and heavy metals is dominated by wet deposition in areas near the petrochemical plant and by dry deposition in areas near the cement plant. Coal combustion, industrial emissions, and traffic-related activities lead to the enrichment of heavy metals in the snowpacks of urban and suburban areas, while coal combustion and biomass burning contribute to pollution in rural areas. The cities and regions situated in the western, northwestern, northern, and northeastern directions from Harbin are potential source regions of these pollutant species.

[Characteristics and Generation Mechanism of Secondary Inorganic Ions in PM2.5 in Changsha-Zhuzhou-Xiangtan City Group].

Secondary inorganic ions, the main components of atmospheric PM2.5, are a dominant contributor to haze formation. The detailed characteristics and main generation mechanism of secondary inorganic ions in PM2.5 are still unclear in the Changsha-Zhuzhou-Xiangtan City Group, which is suffering from severe haze pollution, particularly in the autumn and winter seasons. For our study, we collected PM2.5 samples in November 2020 and January 2021 from four urban sites in the Changsha-Zhuzhou-Xiangtan City Group. Secondary inorganic components such as SO42-, NO3-, and NH4+ in PM2.5 were quantified. The average values(µg·m-3) of ρ(SO42-), ρ(NO3-), and ρ(NH4+) in autumn and winter were(5.2±2.5) and(7.9±4.8),(4.1±2.2) and(7.2±4.2), and(17.1±10.5) and(7.8±5.2), respectively. During the heavy haze pollution events in winter, the sum of ρ(SO42-), ρ(NO3-), and ρ(NH4+)(SNA) contributed 72.7% to the growth of PM2.5 mass concentration, and ρ(NO3-) accounted for 41.2%. This result suggested that the generation of NO3- was the key factor leading to the formation of winter haze pollution. In the polluted stage, high aerosol water content(AWC) promoted the rapid secondary generation of SNA, whereas adverse meteorological conditions also led to the accumulation of pollutants. The values of sulfur oxidation rate(SOR) and nitrogen oxidation rate(NOR) were still high in the dissipation stage. It indicated that the PM2.5 concentration fell due to the reduction in primary emissions and favorable weather conditions in dissipation, instead of the weakening of secondary generation of SNA. Compared to that in autumn, the higher AWC concentration, pH value, and lower temperature in winter were the main factors for the higher ρ(NO3-)/ρ(PM2.5) and NOR values in the Changsha-Zhuzhou-Xiangtan City Group. At the same time, the heterogeneous reaction was the main generation pathway of NO3-, when the AWC concentration was high in winter. Affected by aerosol pH value and generation rate, the liquid-phase oxidation reactions of H2O2 and SO2 were the main generation pathways of SO42- in autumn and winter in the Changsha-Zhuzhou-Xiangtan City Group. Compared to that in autumn, the higher AWC was more conducive to forming SO42-, which led to higher SOR in winter.

Role of inorganic ions in wound healing: an insight into the various approaches for localized delivery.

Recently, the role of inorganic ions has been explored for its wound-healing applications. Ions do play key role in the normal functioning of the skin, including the epidermal barrier property, maintaining redox balance, enzymatic activities, tissue remodeling, etc. The care of chronic wounds is a concern and new cost-effective therapeutic strategies that modulate the wound microenvironment and cell behaviour are needed. First, this review illustrates the ions that play a role in wound healing and their molecular mechanisms that are accountable for modifying the wound. Further, the emerging strategies using metal ions to modulate the healing will be discussed. In this direction, localized delivery of inorganic ions of importance using advanced wound care biomaterials for wound healing applications is discussed.

The wound repair and regeneration process is regarded as a highly complex biological process that involves multiple phases. Chronic wounds are those that get stalled at the initial phases of wound healing. This review discusses the role of inorganic ions in wound healing and its therapeutic potential that could improve healing outcomes in chronic wounds. Utilizing inorganic ions in innovative ways to modulate the wound-healing processes is an emerging field. In this regard, the review paper also encompasses a comprehensive overview of numerous delivery approaches for the localized release of metal ions to the wound site.

Comparison of chemical composition and acidity of size-resolved inorganic aerosols at the top and foot of Mt. Hua, Northwest China: The role of the gas-particle distribution of ammonia.

Aerosol pH is not only a diagnostic indicator of secondary aerosol formation, but also a key factor in the specific chemical reaction routes that produce sulfate and nitrate. To understand the characteristics of aerosol acidity in the Mt. Hua, the chemical fractions of water-soluble inorganic ions in the atmospheric PM2.5 and size-resolved particle at the top and foot of Mt. Hua in summer 2020 were studied. The results showed the mass concentrations of PM2.5 and water-soluble ions at the foot were 2.0-2.6 times higher than those at the top. The secondary inorganic ions, i.e., SO42-, NO3-, and NH4+ (SNA) were 56 %-61 % higher by day than by night. SO42- was mainly distributed in the fine particles (Dp < 2.1 µm). NO3- showed a unimodal size distribution (peaking at 0.7-1.1 µm) at the foot and a bimodal (0.7-1.1 µm and 4.7-5.8 µm) size distribution at the top. At the top site, the distribution of NO3- in coarse particles (> 2.1 µm) was mainly attributed to the gaseous HNO3 volatilized from fine particles reacting with cations in coarse particles to form non-volatile salts (such as Ca(NO3)2). The pH values of PM2.5 were 2.7 ± 1.3 and 3.3 ± 0.42 at the top and foot, respectively. NH4+/NH3(g) plays a decisive role in stabilizing aerosol acidity. In addition, the increase of the liquid water content (LWC) at the foot facilitates the gas-particle conversion of NH3, while the H+ concentration was diluted, resulting in a decrease in acidity at the foot. NH4+/NH3 had good linear correlations with SO42-, NO3-, and LWC during the daytime at both sites, indicating that SO42-, NO3-, and LWC together affect the gas-particle distribution of ammonia by day: however, the effect of LWC at night was not evident.

Environmental Applications of Electromembrane Extraction: A Review.

Electromembrane extraction (EME) is a miniaturized extraction technique that has been widely used in recent years for the analysis and removal of pollutants in the environment. It is based on electrokinetic migration across a supported liquid membrane (SLM) under the influence of an external electrical field between two aqueous compartments. Based on the features of the SLM and the electrical field, EME offers quick extraction, effective sample clean-up, and good selectivity, and limits the amount of organic solvent used per sample to a few microliters. In this paper, the basic devices (membrane materials and types of organic solvents) and influencing factors of EME are first introduced, and the applications of EME in the analysis and removal of environmental inorganic ions and organic pollutants are systematically reviewed. An outlook on the future development of EME for environmental applications is also given.

Residential combustion of coal: Effect of the fuel and combustion stage on emissions.

Worldwide coal is still used for household heating purposes not only because it is available and cheap but also due to behavioural issues. Regional variability in fuels and combustion appliances make accurate emission estimates from this source hard to achieve. In the present study, gaseous (CO, VOCs, SO2 and NOX) and particulate matter (TSP) emission factors (EFs) were determined for Spanish household coal combustion covering three commercial coals and distinct combustion stages and mimicking usage patterns in real households. TSP samples were analysed to determine water-soluble inorganic ions, metal(loid)s, and organic and elemental carbon (OC and EC). Additionally, the morphology of the emitted particles was also characterised. CO (3.43-169 g kg-1), NOX (1.29-6.00 g kg-1) and SO2 (8.96-22.3 g kg-1) EFs showed no trend regarding the combustion stage or coal type tested. On the other hand, VOC, TSP and EC EFs were higher for the ignition/devolatilisation combustion stage, regardless of the fuel tested. TSP EFs (0.085-1.08 g kg-1) increased with increasing coal volatile matter while the opposite trend was recorded for VOC emissions (0.045-3.39 gC kg-1). TSP carbonaceous matter was dominated by EC while OC represented a small fraction of the particulate mass emitted (less than 8 %wt.). Inorganic compounds composed an important fraction of the TSP samples. Sulphate particulate mass fractions (8.66-22.9 %wt.) appeared to increase with coal S-content. Coal combustion released particles with diverse morphologies, including silicate-rich particles, ferro- and glassy-spheres. This study provides novel emission factors to update emission inventories of residential coal combustion. Additionally, detailed chemical profiles were obtained for source apportionment.

Water-soluble inorganic ions (WSIs) in the aerosols from Central Asia via transboundary transport measured in Jimunai in 2020.

Air pollution is a global issue that often transcends national borders, leading to disputes over environmental concerns and climate-mitigation responsibilities. Between March and July 2020, we collected aerosol samples in Jimunai, a town in western China neighboring Kazakhstan, to assess transboundary air pollution in the region. Our analysis focused on major water-soluble inorganic ions (WSIs), with Ca2+ and SO42- accounting for almost 60% of the total ion loading. The ratio of cations to anions was greater than one (1.33 ± 0.27), indicating alkaline aerosols during the sampling period. Our results suggest that the pollutants measured were primarily sourced from Kazakhstan, as demonstrated by local meteorological data, air-mass trajectory analysis, and pollutant emission inventories in Kazakhstan. Correlation and primary component analysis indicated that NH4+ played an important role in neutralizing NO3- and SO42-, while Cl- was significantly depleted by the probable reaction HNO3↑ + NaCl = HCl↑ + NaNO3. These findings highlight the need for continued monitoring and regulation of air pollution sources in the region to address transboundary air pollution.

The effect of multiple factors on water-soluble inorganic ions in diesel particulate matter emissions.

The water-soluble inorganic ions (WSII) in diesel particulate matter (DPM) have a significant impact on ambient air quality and human health. In this study, the 12 groups of bench tests were conducted to analyze the emission characteristics of two diesel engines, taking into account the influence of engine parameters, test cycle, fuel types, and after-treatment measures. Compared to conventional diesel, a blend of diesel with 5 % biodiesel resulted in a reduction of the WSII emission factors by 23.7-48.0 %. The emission factors of WSII decreased by 8.4 % after installing selective catalytic reduction (SCR). Dummy variable regression analysis was used to analyze the relationship between WSII and influencing factors. The emission factors of Na+, K+, and Ca2+ were mostly affected by the engine, potentially due to the use of coolants and lubricants containing metal oxides in the engine. The emission factors of NO3- were mainly affected by the test cycle. Techniques for order preference by similarity to ideal solution (TOPSIS) were used to analyze the priority of emission reduction technologies. The results indicated that SCR, biodiesel, and low-sulfur diesel could effectively reduce WSII. This study aims to explore the influence of multiple factors on WSII, providing valuable insights for future research on WSII in DPM.

Changes of water-soluble inorganic sulfate and nitrate during severe dust storm episodes in a coastal city of North China.

Dust storms are one of the largest sources of non-exhaust emissions in China, which can adversely affect air quality and human health during long-distance transportation. To study the influence of dust storms on aerosol particle composition, samples of fine aerosol (PM2.5) were collected before, during, and after the severe dust storm episodes in a coastal city of North China. Then the water-soluble inorganic ions in the filters were analyzed. The results showed that the chemical composition varied significantly in different sampling periods. Before the dust storm periods (Phase 1), the weather was characterized by high relative humidity. NO3- was the main water-soluble inorganic ion, accounting for about 1/3 of the total mass of PM2.5, which is very different from the situation a few years ago when sulfate was the dominant. The results indicated that the chemical composition of the atmosphere in China has changed significantly after the implementation of strict air pollution control measures. During the severe dust storm periods (within a few hours after the dust invasion, Phase 2), the proportion of Ca2+ in PM2.5 was high; the sulfate formation was limited due to adiabatic air mass affected by the cold front, and the sulfate content might be mainly from desert soil. However, a small amount of nitrate can be formed during their long-distance transportation. After the dust storm periods (Phase 3), dust plums and local polluted air mass mixed well. The proportion of secondary inorganic ions increased, and nitrate formation was still the main. The changes in the chemical composition from a few years ago during Phase 1 and the sharp changes in different water-soluble inorganic ions during different Phases should be carefully considered to evaluate their implications for air quality and human health.

The chemistry of an insect ear: ionic composition of a liquid-filled ear and haemolymphs of Neotropical katydids.

The purpose of this study is to examine and to compare the ionic composition of the haemolymph and the ear fluid of seven species of katydids (Orthoptera: Tettigoniidae) with the aim of providing from a biochemical perspective a preliminary assessment for an insect liquid contained in the auditory organ of katydids with a hearing mechanism reminiscent of that found in vertebrates. A multi-element trace analysis by inductively coupled plasma optical-emission spectrometry was run for 16 elements for the ear liquid of seven species and the haemolymph of six of them. Based on the obtained results, it can be recognized that the ionic composition is variable among the studied insects, but sodium (Na+), potassium (K+), calcium (Ca2+) and magnesium (Mg2+) are the most prominent of the dissolved inorganic cations. However, the ion concentrations between the two fluids are considerably different and the absence or low concentration of Ca2+ is a noticeable feature in the inner ear liquid. A potential relationship between the male courtship song peak frequency and the total ion (Na+, K+, Mg2+ and Ca2+) concentration of the inner ear liquid is also reported.

Characterization of fine particulate matter water-soluble inorganic ions and estimation of aerosol acidity at three COALESCE network sites - Mysuru, Bhopal, and Mesra - in India.

The study was carried out to understand the chemical, spatiotemporal characteristics of water-soluble inorganic ions (WSIIs), their association with PM2.5 mass, and aerosol acidity in three COALESCE (carbonaceous aerosol emissions, source apportionment, and climate impacts) network sites of India (Mesra - Eastern India, Bhopal - Central India and Mysuru - Southern India). Alternate-day 24-h integrated bulk PM2.5 samples were collected during 2019 along with on-site meteorological parameters. Annual average PM2.5 concentrations were 67 ± 46 µg m-3, 54 ± 47 µg m-3, and 30 ± 24 µg m-3 at Mesra, Bhopal, and Mysuru, respectively. PM2.5 concentrations exceeded the annual mean (40 µg m-3) recommended by the National Ambient Air Quality Standards (NAAQS) at Mesra and Bhopal. WSIIs existed in PM2.5 mass at Mesra (50.5%), Bhopal (39.6%), and Mysuru (29.2%). SO42-, NO3-, and NH4+ (SNA) were major secondary inorganic ions in total WSIIs, with an annual average of 88.4% in Mesra and 82.0% in Bhopal 78.4% in Mysuru. Low NO3-/SO42- ratios annually at Mesra (0.41), Bhopal (0.44), and Mysuru (0.24) indicated that stationary sources dominated vehicular emissions (1.0). Aerosol acidity varied from region to region and season to season depending on the presence of NH4+, the dominant counter-ion to neutralize anions. Aerosols were near-neutral or alkaline at all three sites, except during the pre-monsoon season in Mysuru. An assessment of neutralization pathways for major anions [SO42- + NO3-] suggests that they mainly existed as sulfate and nitrate salts such as ammonium sulfate ((NH4)2SO4) and ammonium bisulfate (NH4HSO4) in conjunction with ammonium nitrate (NH4NO3).

[Pollution Characteristics and Sources of Water-soluble Ions in PM2.5 in Zhengzhou City].

In order to explore the pollution characteristics, seasonal variations, and sources of water-soluble inorganic ions (WSIIs) in PM2.5 in Zhengzhou, PM2.5 samples were seasonally collected from December 2020 to October 2021; then, combining gaseous pollutants (SO2, NO2, and O3) and meteorological parameters (temperature and relative humidity), nine WSIIs (NO3-, NH4+, SO42-, Ca2+, K+, Na+, Mg2+, F-, and Cl-) were analyzed. The results showed that the annual average concentration of the total water-soluble ions (TWSIIs) was (39.34±21.56) µg·m-3for the four seasons, showing obvious seasonal variations with the maximum value in winter and the minimum value in summer. Annual PM2.5 was slightly alkaline in Zhengzhou, and NH4+ most likely existed in the form of NH4NO3 and (NH4)2SO4. The average sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) were 0.35 and 0.19, respectively, indicating that SO42- and NO3- mainly derived from secondary formation. The main potential source regions of WSIIs obtained by the concentration weight trajectory (CWT) model showed temporal and spatial variations. The significant sources of WSIIs based on principal component analysis (PCA) were dust, secondary generation, combustion, and industrial activities, which were obviously influenced by wind direction and speed in Zhengzhou.