Dominant Ion Research Articles

Characterization of Water-Soluble Ions in PM2.5 in Chongqing, a Megacity in Eastern Sichuan Basin, China

Samples of PM2.5 were collected at three urban sites and one rural site simultaneously in Chongqing, the only megacity in eastern Sichuan Basin, Southwest China, from October 15 to November 13, 2015. Water-soluble ions (WSIs, i.e., F–, Cl–, NO3–, SO42–, K+, Na+, NH4+, Mg2+ and Ca2+) in PM2.5 were measured to investigate their characteristics and formation pathways. The average concentrations of PM2.5 at the urban sites were 55.5–59.0 µg m–3, which was 62.8–73.0% higher than that at rural site. SO42–, NO3–, NH4+ were the dominant ions, contributing to more than 90% of total WSIs. The coefficients of divergence for SO42– between the urban and rural sites were 0.15–0.17, indicating its relatively uniform distribution across Chongqing. Analysis of the formation mechanisms of SO42– and NO3– in PM2.5 suggested that the heterogeneous reaction was responsible for the high concentrations of sulfate among the four sites, whereas nitrate was formed mainly through homogeneous reactions at the urban sites. Furthermore, the results of trajectory clustering showed that the air pollution were mainly from local sources within the basin. Our findings on PM2.5 composition in Chongqing help to advance the knowledge on PM2.5 pollution in Chinese megacities, and to provide more evidence for further pollution mitigation.

Physicochemical Model of Silver Behavior in a Weathering Profile

A weathering profile of phyllite shales with an original Ag concentration of 10–5 wt % (the average Ag concentration in the Earth’s crust is 7 × 10–6 wt %) was numerically simulated with the SELECTOR program package. Under oxidizing conditions, Ag occurs in the solutions dominantly in the form of the $${\text{Ag}}_{{({\text{aq}}{\text{.}})}}^{ + }$$ cation and a few percent of the anion , at a total Ag concentration of ×10–6.4 mol/L. Under reduced conditions, the dominant ion is $${\text{Ag}}_{{({\text{aq}}{\text{.}})}}^{0}$$, whose concentration is 10–8.19 mol/L. The mineral form of Ag throughout the whole vertical section is native silver.

Predictive multi-channel flux-driven modelling to optimise ICRH tungsten control and fusion performance in JET

The evolution of the JET high performance hybrid scenario, including central accumulation of the tungsten (W) impurity, is reproduced with predictive multi-channel integrated modelling over multiple confinement times using first-principle based core transport models. Eight transport channels () are modelled predictively, with self-consistent sources, radiation and magnetic equilibrium, yielding a system with multiple non-linearities: This system can reproduce the observed radiative temperature collapse after several confinement times. W is transported inward by neoclassical convection driven by the main ion density gradients and enhanced by poloidal asymmetries due to centrifugal acceleration. The slow evolution of the bulk density profile sets the timescale for W accumulation. Modelling this phenomenon requires a turbulent transport model capable of accurately predicting particle and momentum transport (QuaLiKiz) and a neoclassical transport model including the effects of poloidal asymmetries (NEO) coupled to an integrated plasma simulator (JINTRAC). The modelling capability is applied to optimise the available actuators to prevent W accumulation, and to extrapolate in power and pulse length. Central NBI heating is preferred for high performance, but gives central deposition of particles and torque which increase the risk of W accumulation by increasing density peaking and poloidal asymmetry. The primary mechanism for ICRH to control W in JET is via its impact through turbulence in reducing main ion density peaking (which drives inward neoclassical convection), increased temperature screening and turbulent W diffusion. The anisotropy from ICRH also reduces poloidal asymmetry, but this effect is negligible in high rotation JET discharges. High power ICRH near the axis can sensitively mitigate against W accumulation, and dominant ion heating (e.g. He-3 minority) is predicted to provide more resilience to W accumulation than dominant electron heating (e.g. H minority) in the JET hybrid scenario. Extrapolation to DT plasmas finds 17.5 MW of fusion power and improved confinement compared to DD, due to reduced ion-electron energy exchange, and increased Ti/Te stabilisation of ITG instabilities. The turbulence reduction in DT increases density peaking and accelerates the arrival of W on axis; this may be mitigated by reducing the penetration of the beam particle source with an increased pedestal density.

A Forty-Year Karstic Critical Zone Survey (Baget Catchment, Pyrenees-France): Lithologic and Hydroclimatic Controls on Seasonal and Inter-Annual Variations of Stream Water Chemical Composition, pCO2, and Carbonate Equilibrium

The long-term trends and seasonal patterns of stream water chemical composition in a small remote forested karst catchment, were investigated from 1978 to 2018. Calcium, magnesium, and bicarbonates, the dominant ions, increased over the period together with temperature, while sulfates decreased. Carbonate and sulfate mineral dissolution was the main source of these elements. These trends and the seasonal opposite patterns of discharge vs. temperature, calcite saturation index vs. pCO2 and bicarbonate vs. sulfates, suggested the influence of discharge, of reduced long-range atmospheric pollution, and of increasing air temperature on biological activity and carbonate dissolution. Furthermore, the hydrological regime controlled the seasonal stream water chemical composition and fluxes by: (i) a dilution during the high discharge period, (ii) a change in the contribution rate of the waters draining different lithological areas in the catchment, e.g., the increased sulfates to bicarbonates ratio during summer low flows, with a maximum alkalinity decrease of 24%, and (iii) a “piston” and a “flushing” effects of dissolved elements stored in soils and epikarst with the first autumn heavy rains. Long-term stream water hydrochemical surveys of karst system have proved to be powerful indicators of biogeochemical processes, water sources and pathways under variable natural and anthropogenic environmental pressure conditions.

Characterization of atmospheric trace gases and water soluble inorganic chemical ions of PM1 and PM2.5 at Indira Gandhi International Airport, New Delhi during 2017–18 winter

Water soluble inorganic chemical ions of PM1 and PM2.5 and atmospheric trace gases were monitored simultaneously on hourly resolution at Indira Gandhi International Airport (IGIA), Delhi during 8 December 2017–10 February 2018. Monitoring was made by MARGA (Monitoring AeRosol and Gases in ambient Air) under winter fog experiment (WIFEX) program of the Ministry of Earth Sciences (MoES), Government of India. The result based on the analysis of the data so generated reveals that Cl−, NH4+, NO3− and SO42− were dominant ions in order which collectively constituted 96.8 and 97.3% of the of the total measured ionic mass in PM1 and PM2.5 respectively. Their overall average concentrations in PM1 were 19.5 ± 19.7, 18.4 ± 10.5, 16.6 ± 8.7 and 10.3 ± 5.7 μg/m3 and in PM2.5 were 36.0 ± 33.9, 32.7 ± 17.2, 28.5 ± 13.6 and 19.9 ± 13.9 μg/m3. Average concentrations of HCl, HNO3, HNO2, SO2 and NH3 trace gases were 0.7 ± 0.3, 2.7 ± 1.1, 6.6 ± 4.7, 22.0 ± 12.3 and 25.7 ± 9.1 μg/m3 respectively. Weather parameters along with low mixing height played significant role in the occurrence of high concentration of these chemical species.NH4+ was the prime neutralizer of the acidic components and mostly occurred in (NH4)2SO4/NH4HSO4, NH4NO3 and NH4Cl molecular forms. Major sources of these chemical species were fossil fuel combustion in aviation activity and transportation, coal burning in thermal power plants, industrial processes and emissions from biomass burning and agro-based activity.The quality of air with respect to PM2.5 always remained deteriorated. It became alarming during low visibility period mainly due to high concentration of Cl−, NO3−, SO42− and NH4+. Both meteorological and chemical processes interactively fed each other which occasionally resulted in fog development and visibility degradation. The knowledge gained by this study will help in simulation of atmospheric processes which lead to fog development and dispersal in the Delhi region.

Induced Fit of Crown Cavity to Ammonium Ion Guests and Photoinduced Intracavity Reactions: Cold Gas-Phase Spectroscopy of Dibenzo-18-Crown-6 Complexes with NH4+, CH3NH3+, and CH3CH2NH3.

Ultraviolet photodissociation (UVPD) spectra of dibenzo-18-crown-6 (DB18C6) complexes with NH4+, CH3NH3+ (MeNH3+), and CH3CH2NH3+ (EtNH3+) [NH4+(DB18C6), MeNH3+(DB18C6), and EtNH3+(DB18C6), respectively] were observed under cold gas-phase conditions. We also measured the infrared (IR)-UV double-resonance spectra of these complexes in the NH stretching region to examine the encapsulation structure. The UVPD and IR-UV spectra were analyzed using quantum chemical calculations. All the ammonium complexes show sharp 0-0 bands at positions close to that of the K+(DB18C6) complex; the conformation of the DB18C6 component in the ammonium complexes is similar to that in K+(DB18C6). In addition, the ammonium complexes each have another type of isomer that the K+(DB18C6) complex does not show in the gas phase. In these isomers, the conformation of the DB18C6 cavity changes, and the strength of the NH···O hydrogen bond increases. During the UVPD, the NH4+(DB18C6) complex provides various photofragment species, such as the C8H9O2+ ion, resulting from cleavage of the DB18C6 component, whereas the dominant fragment ion for the MeNH3+(DB18C6) and EtNH3+(DB18C6) complexes is the ammonium ion itself. The UVPD investigation of deuterated systems suggests that after UV excitation of the NH4+(DB18C6) complex, the dissociation process is initiated by proton transfer from NH4+ to DB18C6, followed by the migration of hydrogen atoms in the crown cavity and the cleavage of the ether ring.

Ecophysiology of a successful phytoplankton competitor in the African flamingo lakes: the green alga Picocystis salinarum (Picocystophyceae)

Picocystis salinarum is a globally widespread picoplanktonic green alga of saline lakes. This tiny alga has been recorded in four continents, and in some cases, it has become the dominant phytoplankton species. We examined the ecophysiology of a Kenyan strain of P. salinarum, collected from Lake Nakuru. The photosynthetic activity of the species was measured in seventy-two combinations of light intensity and temperature. The photosynthetic activity was low along the temperature gradient with an optimum at 31.9 °C; it varied between 0.097 and 1.233 μg C μg−1 Chl a h−1. The ability of P. salinarum to utilize low light intensity (α varied between 0.0061 and 0.1 (μg C μg−1 Chl a h−1) (μmol photons m−2 s−1)−1) and its susceptibility to photoinhibition at different temperatures confirm the species’ preference for low light intensity, which is already shown by its Ik values (1.0–89.3 μmol photons m−2 s−1). The salinity tolerance of P. salinarum, more specifically the effect of changes in the concentration of chloride (NaCl) and carbonate forms (Na2CO3 and NaHCO3), was investigated in continuous cultures. The dominant ion of the medium greatly affected the growth of P. salinarum: significantly higher growth rates were recorded in carbonate form-dominated media as compared to chloride-dominated ones; the highest growth rate was observed at the highest concentration. The observed physiological properties (slow growth, low photosynthetic activity) are not typical of a dominant species; however, the high conductivity tolerance could be a key factor explaining the success of P. salinarum.

Water quality in a worldwide coal mining city: A scenario in water chemistry and health risks exploration

In the face of increasing influences of coal industries on the water environment and water security, a deeper understanding of the chemistry of water and the eco-environmental health risks to human is needed to contribute. One of largest coal capital city of Yulin (NW of China) was chosen a scenario and case for further investigation. The distribution levels of multi-ions (F−, Cl−, HCO3−, NO3−, SO42−, Li+, K+, Ca2+, Na+, Mg2+, NH4+) and potentially toxic metals (PTMs) (Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb and Zn) in drinking water, lake water and river water at the river catchment scale collected from study areas were determined by using ion chromatography and inductively coupled plasma mass spectrometer (ICP-MS). The water chemistry, health risks, sources and anthropogenic inputs were explored. The dominant ions in drinking, lake and river waters decreased as HCO3− > SO42− > Cl− in anions, and cations as Ca2+ > Na+ > Mg2+. The strong correlation between Na+ and Cl−, K+ and Cl−, Na+ and K+, Mg2+ and SO42− in surface waters (lake and river water) was controlled by rock weathering and with the hydrochemical type of SO42−·Cl−—Ca2+·Mg2+ illustrated by the Gibbs diagram. The concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb and Zn in drinking and surface waters were varied significantly, which was associated with coal mining and coal combustion activities. Although the non-carcinogenic risk of Cu, Mn, Ni, Pb, Sb and Zn in drinking water, lake and river water were acceptable, the carcinogenic risk caused by Cr in both drinking water and surface waters exceeded the values of 5.00E-05 and 1.00E-06 recommended by three international health organizations, respectively, which should be paid more attention to and monitored continuously in order to significantly understand the pollutants and the anthropogenic impact on water security and ecosystems, and also to ensure the sustainable clean energy and ecological coal exploitation in Yulin city.

Electron and negative ion dynamics in a pulsed 100 MHz capacitive discharge produced in an O2 and Ar/O2/C4F8 gas mixture

This paper presents an experimental study of electron and negative ion dynamics in a pulsed 100 MHz capacitive discharge. The plasma is produced in an O2 and Ar/O2/C4F8 gas mixture at 2 Pa gas pressure. Laser photo-detachment combined with a microwave resonance probe is used to diagnose the absolute densities of multiple negative ion species, F− and O−. In pure oxygen discharge, both the quasi-steady state electron and negative ion densities increase during the active glow with an increase in RF power level. In the afterglow plasma, the electron density decay rate is ∼10–15 μs, whereas the O− decays more slowly with a decay time constant in the range of 30–35 μs. At a low RF power, a peak in the O− density is observed in the early afterglow plasma. In the Ar/O2/C4F8 gas mixture, the quasi-steady state electron density in the active glow plasma increases with RF power, whereas the O− density decreases and F− density increases. In comparison to pure O2 discharge, in the Ar/O2/C4F8 gas mixture the electron density decay is faster. In the afterglow the F− density is ten times higher than the O− density. These results suggest a change in the dominant negative ion production mechanism within the discharge pulse from dissociative electron attachment of CxFy in the active on-phase to electron attachment to fluorine atoms in the afterglow plasma.

Naturally Occurring Potentially Harmful Elements in Groundwater in Makueni County, South-Eastern Kenya: Effects on Drinking Water Quality and Agriculture

Makueni County is located in the semi-arid south-eastern Kenya region characterized by unreliable rainfall and limited surface water resources. This necessitates a high reliance on groundwater for domestic and agricultural use. In this paper, we report on the physico-chemical characteristics of 20 drinking water sources (boreholes, shallow wells, streams, and tap water) collected during the dry season (November 2018), the geochemical processes controlling their composition, and their suitability for drinking water and irrigation. Of all the physico-chemical parameters analysed, the concentrations of total dissolved solids, hardness, electrical conductivity, magnesium, calcium, chloride, and fluoride exceeded the permissible drinking water limits set by both the World Health Organization (WHO) and Kenya Bureau of Standards (KEBS) in up to 55% of the samples. The dominant ions reflect the high salinity in the water that ranged from very high to extreme in up to 50% of samples. The northern region shows the highest concentrations of the dominant parameters. The water type is predominantly Ca-Mg-HCO3 with a trend to Ca-Mg-Cl-SO4. Rock weathering and evaporation are suggested to be the primary controls of groundwater geochemical characteristics. High salinity and fluoride, which are associated with reported undesirable taste and gastrointestinal upsets, as well as cases of dental fluorosis are some of the effects of consuming groundwater in the region. These two parameters can be attributed to the weathering of biotite gneisses, granitoid gneisses, migmatites, and basaltic rocks that occur in the area. The high salinity and alkalinity of most of the samples analysed, renders the water unsuitable for irrigation in the study area.

A novel contrast of the reactions of 2,4,6-trinitrotoluene (TNT) in atmospheric-pressure O2 and N2 plasma: Experimental and theoretical study

Negative-mode ion/molecule reactions of 2,4,6-trinitrotoluene (TNT) generated in atmospheric-pressure O2 and N2 corona discharge plasmas were studied. In the O2 plasma, charge transfer reaction, O2−• + TNT → O2 + TNT−•, was found as the major reaction channel. The proton abstraction reaction, O2−• + TNT → O2H• + [TNT − H+]−, was negligible, which is in sharp contrast to the formation of [DNT − H+] and [NT − H+] (DNT: 2,4-dinitrotoluene and NT: 2-nitrotoluene). TNT−• further reacts with O3 to form [TNT−NO•]− and [TNT−OH•]−. In atmospheric-pressure N2 plasma, TNT−• was detected as the dominant ion with no fragment ions.Adiabatic electron affinity (EA) of TNT was estimated by density functional theory (DFT) calculations as 2.08 eV. The precise mechanisms of the charge transfer, O2−• + TNT → TNT−• + O2, and TNT−• + O3 were examined by the frontier-orbital theory. The charge transfer may be attained by the specific O2−• coordination on the benzene ring of TNT. Reaction paths of [TNT + O3]−• leading to [TNT − OH•]− and [TNT − NO•]− were investigated by bimolecular reaction of TNT−• with O3. The formation of [TNT−NO•]− was found to be energetically more favorable than that of [TNT−OH•]−.

Suprathermal Fe in the Earth's Plasma Environment: Cluster RAPID Observations

AbstractBaryonic matter in geospace is almost exclusively in a plasma state, with protons (H ) and to some extent ionized helium (He) and oxygen (O) being the dominant ion species. But also other heavier ion species and even molecular ions are present in geospace. The Research with Adaptive Particle Imaging Detectors (RAPID) on board the Cluster satellites can identify and characterize some of these ions by utilizing their measured time of flight and energy. Usually, the measurements are then assigned into three discrete species channels; protons (H ), helium (He), and a common channel for carbon, nitrogen, and oxygen (CNO), each with flux, energy, and angular information. But RAPID also has a Direct Event (DE) diagnostic mode in which the full time of flight and energy information for a limited number of incident particles are stored. With knowledge about energy losses in the various detector parts, it is then possible to derive the atomic mass of the incident particle. In this paper we report on results from a study of Cluster DE events during the years 2001–2018, with a particular emphasis of iron (Fe) ions. We show that suprathermal Fe ions can be found all over geospace covered by Cluster, and that the time variation is consistent with modulation by geomagnetic disturbances and solar activity. We do not find any clear correlations between detection of suprathermal Fe and meteor showers or sputtering off the moon.

Sugar, amino acid and inorganic ion profiling of the honeydew from different hemipteran species feeding on Abies alba and Picea abies.

Several hemipteran species feed on the phloem sap of plants and produce large amounts of honeydew that is collected by bees to produce honeydew honey. Therefore, it is important to know whether it is predominantly the hemipteran species or the host plant to influence the honeydew composition. This is particularly relevant for those botanical and zoological species from which the majority of honeydew honey originates. To investigate this issue, honeydew from two Cinara species located on Abies alba as well as from two Cinara and two Physokermes species located on Picea abies were collected. Phloem exudates of the host plants were also analyzed. Honeydew of all species contained different proportions of hexoses, sucrose, melezitose, erlose, and further di- and trisaccharides, whereas the phloem exudates of the host trees contained no trisaccharides. Moreover, the proportions of sugars differed significantly between hemipteran species feeding on the same tree species. Sucrose hydrolysis and oligosaccharide formation was shown in whole-body homogenates of aphids. The type of the produced oligosaccharides in the aphid-extracts correlated with the oligosaccharide composition in the honeydew of the different aphid species. The total contents of amino acids and inorganic ions in the honeydew were much lower than the sugar content. Glutamine and glutamate were predominant amino acids in the honeydew of all six hemipteran species and also in the phloem exudates of both tree species. Potassium was the dominant inorganic ion in all honeydew samples and also in the phloem exudate. Statistical analyses reveal that the sugar composition of honeydew is determined more by the hemipteran species than by the host plant. Consequently, it can be assumed that the sugar composition of honeydew honey is also more influenced by the hemipteran species than by the host tree.

Pollution characteristics, sources, and health risk assessments of urban road dust in Kuala Lumpur City

Urban road dust contains anthropogenic components at toxic concentrations which can be hazardous to human health. A total of 36 road dust samples from five different urban areas, a commercial (CM), a high traffic (HT), a park (GR), a rail station (LRT), and a residential area (RD), were collected in Kuala Lumpur City followed by investigation into compositions, sources, and human health risks. The concentrations of trace metals in road dust and the bioaccessible fraction were determined using inductively couple plasma-mass spectrometry (ICP-MS) while ion concentrations were determined using ion chromatography (IC). The trace metal concentrations were dominated by Fe and Al with contributions of 53% and 21% to the total trace metal and ion concentrations in road dust. Another dominant metal was Zn while the dominant ion was Ca2+ with average concentrations of 314 ± 190μgg-1 and 3470 ± 1693μgg-1, respectively. The most bioaccessible fraction was Zn followed by the sequence Sr > Cd > Cr > Cu > Ni > Co > Mn > As > V > Pb > Fe > Al > U. The results revealed that the highest trace metal and ion concentrations in road dust and in the bioaccessible fraction were found at the LRT area. Based on the source apportionment analysis, the major source of road dust was vehicle emissions/traffic activity (47%), and for the bioaccessible fraction, the major source was soil dust (50%). For the health risk assessments, hazard quotient (HQ) and cancer risk (CR) values for each element were < 1 and in the tolerable range (1.0E-06 to 1.0E-04), except for As for the ingestion pathway. This result suggests a low risk from non-carcinogenic and probable risk from carcinogenic elements, with higher health risks for children compared to adults.

Interaction of (CCl4)n clusters with nanosecond and picosecond laser pulses at discrete wavelengths spanning from IR to UV region: A comparative study using TOFMS

Using time-of-flight mass spectrometer (TOFMS), photochemistry of carbon tetrachloride clusters ((CCl4)n) has been investigated upon interaction with nanosecond and picosecond Nd:YAG laser pulses (266, 355, 532 and 1064 nm) spanning over intensity range of ∼1.2 × 109 to 7.9 × 1012 W/cm2. At all the laser wavelengths upon interaction of (CCl4)n clusters with laser pulse, multiphoton excitation leads to excessive fragmentation of cluster constituents, which are subsequently ionized by multiphoton absorption process. Depending on laser wavelength and pulse duration, at 266 and 355 nm these clusters exhibit dominant ion signal corresponding to singly charged fragment ions i.e. Cl+, CCl+, CCl2+ and CCl3+ in the mass spectra. In addition, for studies carried out at 266 nm using picosecond laser pulses minor ion signal corresponding to C2Cl+ and C2Cl2+ were also observed. Generation of these ions has been ascribed to intra-cluster radical chemistry resulting in generation of neutral precursors, which subsequently are multiphoton ionized. At 532 and 1064 nm, dominant ion signal corresponding to multiply charged atomic ions of carbon (up to C4+/C5+) and chlorine (up to C11+) have been observed. Though multiphoton absorption is the primary process driving the photochemistry of (CCl4)n clusters, observation of multiply charged atomic ions at 532 and 1064 nm has been ascribed to dominant role played by quasi-free electrons which are confined within the ionized cluster, in efficient coupling of laser energy at longer laser wavelengths via inverse Bremsstrahlung process.

Groundwater quality evaluation for different uses in the lower Ketar Watershed, Ethiopia.

Groundwater quality samples from 33 wells were collected in the lower Ketar watershed (Ethiopia) to study its suitability for domestic and irrigation purposes. Samples were evaluated for major ions and physicochemical properties. In 58% of the samples analyzed, Ca2+ is the dominant cation and Na+ dominates the remaining 42% of the samples. Among the anions found during analyzation, HCO3- is the solo dominant ion in all the wells sampled. The order of the concentration of the major ions was Ca2+ > Na+ > Mg2+ > K+ for the cations and HCO3- > SO42- > Cl > NO3- for the anions. AquaChem analysis shows that Ca-HCO3 and Na-HCO3 are the major water types in the area. The analyses indicated that the dissolution of fluorite or fluorapatite is the possible source of the high fluoride concentration in the area. And, the interactions between water and rock and cation exchanges mainly determine the water quality. The suitability of the groundwater for use in irrigation was evaluated based on the salinity (EC), SAR, %Na, RSC, PI, KR, and the USSL Salinity diagram. The groundwater from most of the wells can be used for irrigation without any significant restriction except for a few of the wells downstream. Its suitability for domestic use was evaluated by comparing with the WHO standard limits. The parameters limiting the use of this groundwater for drinking purposes are F- (94%), HCO3- (45%), and Ca2+ (33%). All the remaining major cations and anions complied with the WHO standard limits for drinking.

The Amur River Water During the Winter Low-water Period: The Many-year dynamics of the Sulfates Content and Runoff

Sulfates are the dominant ions among the major ones in the Amur region’s sewage. Therefore, the purpose of the research is to study the long-term dynamics of the content and runoff of sulfates in the Amur River in the winter low-water, based on the materials of Roshydromet for 1943-1976 and the author’s data for 1999-2019.Significant variations in the main areas were found due to both the diversity of natural conditions and anthropogenic influence in the areas of large cities and localities. The impact of the construction of hydroelectric power plants, significant economic changes in the Chinese part of the Amur basin, as well as the closure of pulp and paper and microbiological industries in the Russian part of the Amur basin on the long-term dynamics of the content and flow of sulfates is estimated. The maximum content of sulfates in the Amur River was observed after the accident at the Jilin chemical plant in China in December 2005. The influence of major floods on the increase in the flow of sulphates in the winter low-water was established.

Многолетняя динамика содержания и стока сульфатов в воде реки Амур в зимнюю межень.

ulfates are the dominant ions among the major ones in the Amur region’s sewage. Therefore, the purpose of the research is to study the long-term dynamics of the content and runoff of sulfates in the Amur River in the winter low-water, based on the materials of Roshydromet for 1943-1976 and the author’s data for 1999-2019.Significant variations in the main areas were found due to both the diversity of natural conditions and anthropogenic influence in the areas of large cities and localities. The impact of the construction of hydroelectric power plants, significant economic changes in the Chinese part of the Amur basin, as well as the closure of pulp and paper and microbiological industries in the Russian part of the Amur basin on the long-term dynamics of the content and flow of sulfates is estimated. The maximum content of sulfates in the Amur River was observed after the accident at the Jilin chemical plant in China in December 2005. The influence of major floods on the increase in the flow of sulphates in the winter low-water was established.

Comparison of PM2.5 Chemical Compositions during Haze and Non-haze Days in a Heavy Industrial City in North China

This study aimed to determine the chemical composition, sources and contributing factors of airborne PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 µm) during a haze episode in Zibo, a heavy industrial city in China. Samples of PM2.5 were collected 8–27 January 2018 and analyzed for water-soluble inorganic ions (WSIs), trace elements (TEs), organic carbon (OC) and elemental carbon (EC). The PM2.5 concentration was 76.78% higher during the haze (mean ± standard deviation [SD] = 211 ± 39 µg m–3) than before it (49 ± 38 µg m–3), and the dominant ions were NO3–, SO42– and NH4+. Additionally, an elevated TE concentration was observed during the episode (exceeding the pre- and post-haze values by 54.70% and 31.98%, respectively), with crustal elements (K, Al, Ca, Si, Na, Fe and Mg), the most abundant elemental components, accounting for 88.64%. Carbonaceous species (OC and EC) contributed 15.45% of the PM2.5 on haze days and slightly more on non-haze days. The NO3–/SO42– and OC/EC ratios indicated that coal combustion and motor vehicle emission were the primary sources of pollution, and back-trajectory analysis revealed that the air masses over Zibo on haze days mainly originated in adjacent areas in Shandong Province and the Beijing-Tianjin-Hebei region (BTH). The haze episode was caused by a combination of unfavorable meteorological conditions, secondary formation, the accumulation of local pollutants, and peripheral transmission.

Current state of lakes in Northern Yakutia (diatom algae and abiotic parameters)

The review shows the definition of morphometric characteristics, water chemical parameters and diatom assemblages of lakes located in the Arctic zone of Yakutia, in catchments of Anabar, Olenek, Lena, Indigirka and Kolyma Rivers. Main amount of these lakes has small water areas and low depth. The lakes are ultra fresh and mainly with neutral pH, characterized by moderate transparency (on average 43 % of a maximum water depth) and increased concentrations of total iron, silicon, phosphate and ammonium ions. More than the half of the lakes are characterized by exceed of the fishery limits in total iron and phosphate concentrations. In most cases, the dominant major ions are hydrocarbonates and calcium. 502 species and subspecies of 92 genera of diatoms have been discovered in the studied lakes. The highest number of species are included in such genera as Eunotia (38 taxa), Pinnularia (33), Nitzschia (30), Navicula (29), Gomphonema (20) and Achnanthes (17). The most broadly occurred species Tabellaria flocculosa, T. fenestrata, Staurosirella pinnata, Staurosira venter, S. construens, Achnanthidium minutissimum and Eunotia praerupta. Diatom assemblages of the lakes are characterized by a rather high diversity and evenness. The Pantle-Buck saprobity index, calculated inferred from known values of indicative significance of diatoms, indicates that most of the lakes have clean water. Water of 16.9 % lakes is moderate polluted.