SO4 Concentrations Research Articles

Evaluation of Ionic Osmotica in Succulent and Non-succulent Xero-halophytes Inhabiting Hot Oases

This research was carried out at Kharga and Dakhla, in the western Egyptian desert. The species investigated include basically those of different ecological affiliations as well as different life forms, in order to have comparative indications in the ionic means of adjustment. During winter and summer, the water soluble ions in both soil and plants were analyzed. Also, the total osmotic water potential and the share of ionic radicals of plants were calculated. The data revealed that, halophytic species maintain osmotic adjustment due to accumulation of ions depending on seasonal and species variation and ionic osmotic potential which were related to chlorides, sodium and potassium. The seasonality or location has the dominant effect on Na+, K+, Cl- and SO4-2 concentrations in halophytes Suaeda and Cressa and affected by the interaction (S x L) in case of Z.coccenium. The ionic osmotic potential of Na+/K+ and Cl- / SO4-2 ratios for salt tolerance in studied species were discussed.

Evaluation of Ionic Osmotica in Succulent and Non-succulent Xero-halophytes Inhabiting Hot Oases

This research was carried out at Kharga and Dakhla, in the western Egyptian desert. The species investigated include basically those of different ecological affiliations as well as different life forms, in order to have comparative indications in the ionic means of adjustment. During winter and summer, the water soluble ions in both soil and plants were analyzed. Also, the total osmotic water potential and the share of ionic radicals of plants were calculated. The data revealed that, halophytic species maintain osmotic adjustment due to accumulation of ions depending on seasonal and species variation and ionic osmotic potential which were related to chlorides, sodium and potassium. The seasonality or location has the dominant effect on Na+, K+, Cl- and SO4-2 concentrations in halophytes Suaeda and Cressa and affected by the interaction (S x L) in case of Z.coccenium. The ionic osmotic potential of Na+/K+ and Cl- / SO4-2 ratios for salt tolerance in studied species were discussed.

Predictive modeling for U and Th concentrations in mineral and thermal waters, Serbia

The objective of this paper was to determine background values (BV) and anomalous values (AV) of U and Th in groundwater and to establish hydrogeochemical conditions which lead to the elevated concentrations of these elements in groundwater. The methodology included planning and collecting of water samples, laboratory work, and assessment of BV and AV concentrations in accordance with the dataset distribution, based on consideration of hydrogeochemical conditions in the hydrogeological system. Groundwater sampling included 144 occurrences of mineral and thermal water from Serbian territory, belonging to different hydrogeological systems. Field parameters were measured for temperature (T), pH, electrical conductivity (EC), oxidation–reduction potential (ORP), dissolved oxygen (DO), and carbon dioxide (CO2). Standard laboratory measurements were applied for the determination of major chemical components (Ca, Mg, Na, K, Cl, HCO3, and SO4) and U and Th concentrations were measured by ICP-MS. The first step for obtaining U and Th threshold values was based on non-parametric statistical analysis on the data sets. Further analysis of threshold values enabled establishing hydrogeochemical conditions influencing elevated concentrations of U and Th and setting up the logistic regression (LR) model. Differences in the hydrochemical properties of U and Th can be observed based on predictor variables from LR models. Physico-chemical parameters Eh and pH, groundwater type, and geochemical environment (cretaceous igneous rocks) were significant predictors for elevated uranium concentrations, while significant predictors in the thorium LR model were the pH value, the concentration of SO4 in the solution, and the water-bearing rocks (tertiary igneous rocks).

Source apportionment of PM2.5 using online and offline measurements of chemical components in Tianjin, China

PM2.5 and chemical species of water-soluble inorganic ions, carbon components as well as elements were simultaneously measured by online and offline methods in Tianjin, China. Online measured PM2.5, total carbon, and major ions showed good agreement with offline results (r > 0.7), while obvious differences were found for most elements with correlation coefficients lower than 0.6. Online measured ions and most elements (except As, Ca, Ni) showed higher or comparable estimated annual average concentrations than offline results. Sources of PM2.5 were identified by using Positive Matrix Factorization (PMF) model respectively with online and offline data. Higher contributions of secondary source (38%) and secondary sulfate (11%) for online method could be partly caused by higher concentrations of SO42− and NO3− compared to offline method (30%, 10%). Lower source contribution of dust for online (4%) method might partly relate to lower concentration of Ca compared to offline measurement (7%). Different source contribution estimates of vehicle emission and coal combustion between online (18%, 24%) and offline (21%, 25%) may be partly linked to variation of concentrations of OC and EC resulted from different analytical methods. Industrial source, and sea salt & biomass burning showed lower source contributions both online (4%, 1%) and offline (5%, 2%).

Hydrochemical Characteristics and Possible Controls of the Surface Water in Ranwu Lake Basin

To study the chemistry of surface water and potential control measures in the Ranwu Lake basin, 19 samples were collected from Ranwu Lake in 2019. Conventional hydrochemical techniques and statistical analysis methods (descriptive statistics, the Gibbs figure, ion ratio, Piper triangular diagrams) were applied to better understand the solute geochemistry and surface water hydrochemistry in the Ranwu Lake catchment. Surface water in the Ranwu catchment is slightly alkaline (pH of the samples ranged from 7.54 to 8.48 with an average value of 8.06). The concentrations of total dissolved solids (TDS) in the water range from 59.89 to 96.75 mg ·L-1 with an average of 79.98 mg ·L-1, the total dissolved solids of all samples are less than 100 mg ·L-1 and belong to fresh water. The TDS are dominated by Ca2+, Mg2+, HCO3-, and SO42- in the Ranwu Lake. The ion concentrations in the lake water samples are in the order of Ca2+ > Mg2+ > Na+ > K+. The concentrations of Na+and K+are very low. Ranging from 0.5 to 1.21 mg ·L-1, with an average value of 0.58 mg ·L-1, the equivalent concentration of Ca2+ accounts for 63.3% to 76.2% of total cations with an average value of 67.2%. The equivalent concentration of Mg2+ accounts for 23.4% to 36.2% of total cations with an average value of 31.4%. Ca2+ and Mg2+ account for 98.5% of total cations. The main anions were HCO3- and SO42-. The equivalent concentration of HCO3- accounts for 74.31% to 84.29% of total anions with an average value of 78.21%. The equivalent concentration of SO42- accounts for 9.59% to 19.37% of total anions with an average value of 15.34%. HCO3- and SO42- together account for 93.55% of total anions on average. All the water samples fall in the water-rock interaction field, which suggests that the weathering of rocks primarily controls the major ion chemistry of groundwater in this area. Solutes are mainly derived from carbonate weathering and silicate weathering. The role of cation exchange in the geochemical process of the lake and the influence of human activities on the lake are found to be weak.

Groundwater quality assessment of Domiz refugee camp in Duhok governorate, Kurdistan region, Iraq.

Groundwater is considered the fundamental source of drinking uses in Domiz refugee camp, Duhok governorate. Water quality investigation is critical component for determining water consumption. A field assessment was performed on August 2019 in order to examine the groundwater quality used for the refugees in Domiz camp. Groundwater samples were collected from 8 observation wells, 5 wells inside the camp and 3 wells outside the camp limits, and water samples investigated for basic physico-chemical parameters, major elements, as well as certain toxic metals to find out the suitability of groundwater sources for drinking purposes. The analytical out comes display high concentrations of TDS, EC, TH, SO4, and NO3 ions which refers to signs of contamination. Groundwater facies via piper diagram in the study area was primarily of Ca-Mg-Na-HCO3 water type. Heavy metals show high concentration levels in some groundwater samples above drinking water permissible standard prescribed by World Health Organization. These high contents of major elements beside heavy metals in groundwater were probably due to the seepage of unprocessed waste waters from the camp. WQI method were performed to assess the current condition of groundwater samples, then the result revealed variation in water quality classes ranging from very poor to excellent water class

Heavy metal contamination in groundwater and surface water due to active Pb-Zn-Cu mine tails and water-rock interactions: A case study from the Küre mine area (Turkey)

This study aimed at elucidating the groundwater and surface water pollution resulting from water-rock interaction, mine tailings, and mining activities at Küre (Kastamonu) sulfidic Pb-Zn-Cu mine area and its vicinity. The study area has a surface area of approximately 2990 km2. The Küre River drainage site covering the study area is approximately 440 km2. The concentrations of SO4, Al, As, Ba, Mn, Ni, Sb, and Pb in some groundwater (K10, K20, K21, K27, K28, K29, K30), and surface water (KR3) exceed the maximum limit values with respect to the Turkish Standards for Water Intended For Human Consumption and World Health Organization Standards. The most polluted waters were K10, K27, and KR3. The K10 well was drilled for observation at the edge of the liquid mine tailing pond of the Küre Pb-Zn-Cu mine area. The K27 well was opened in alluvium outside of the study area and it cuts the clastic units and Mesozoic ophiolites. The KR3 measurement point is located on the Ersizler River, which drains the Küre Pb-Zn-Cu mining site and its dumps. The SO4, Al, As, Pb, and Sb concentrations of the K10, K27, and KR3 waters were 29.3, 0.8, and 15.1 meq/L; 1135, 1112, and 1186 ppb; 284, 255, and 271 ppb; 19.1, 19, and 18.5 ppb; and 18.7, 17.4, and 19.3 ppb, respectively, in the dry period. As revealed by the analysis, the study area had dual pollution source natural pollution caused by water-rock interactions (K27 and others) and anthropogenic pollution (K10 and KR3) caused by the mine tailings. Furthermore, the K10 water had high tritium (3H)-high electrical conductivity (EC) values that likely indicated anthropogenic contamination. The K27 water had low 3H-high EC values, presumably referring to geogenic contamination. The current study also demonstrated that there was leakage from the liquid mine tailing pond into the groundwater (K10), possibly implying discharge of the liquid mine tailings into the river (KR3).

Characteristics of sulfate-reducing bacteria and organic bactericides and their potential to mitigate pollution caused by coal gangue acidification

High-salinity acid drainage and spontaneous combustion caused by the oxidation of coal gangue piles are one of the pollution sources that seriously harm the environment in coal mine areas. Using sulfate-reducing bacteria, Bacillus subtilis S-19, isolated and identified in the laboratory, a bactericide, which can be used in cooperation with S-19, was screened from sodium dodecyl sulfate (SDS), Kathon (isothiazolinones), and triclosan. Subsequently, the degradation rate of S-19 with respect to organic bactericides was analyzed and a column leaching experiment was conducted to determine the effect of the cooperative repair by organic bactericides and S-19 of the acidification of weathered coal gangue and the inhibition effect on the oxidation of newly generated gangue The results show that: (1) At the minimum inhibitory concentration of Thiobacillus ferrooxidans, the use of only SDS has no inhibitory effect on the growth of S-19. The S-19 strain uses SDS as the carbon source and the degradation rate of SDS reaches 86.90% after 7 d; (2) The SO42− concentration in the leaching solution decreases by 72.19% and the pH increases from 3.15 to 5.21 after 21 d of adding 50 mg⋅ L−1 SDS and S-19 to the weathered gangue filling column, representing a significantly better effect than the treatment with S-19 alone; and (3) S-19 inoculation reduces the concentration of SO42− and soluble salts in the newly produced gangue leaching solution, but it does not increase the pH. There is no significant difference between the effects of the treatments with the combination of S-19 and SDS and S-19 alone.

Effects of forest belt in park on the chemical composition for PM2.5

This paper represents results on the effects of forest belt on seasonal variation on the main chemical components for PM2.5 in the park environment in Beijing. PM2.5 samples were collected inside and outside a conifer forest simultaneously for 1 year in Beijing Olympic Forest Park. Chemical components including organic carbon (OC), elemental carbon (EC), water-soluble ions and elements in PM2.5 were measured. Results indicated that forest belt had significant impacts on PM2.5 chemical compositions of park. Organic matter, SO4 2-, NO3 −, NH4+, and crustal matter were the dominant components of PM2.5. The measured OC was divided into primary OC (POC) and second OC (SOC) parts following the method of EC tracer. Concentrations of OC, SOC, as well as SO4 2-, NO3 −, NH4+ and K+ in PM2.5 inside of forest were markedly higher than those outside of forest. The highest concentrations of OC, EC, and SO4 2- were observed in winter and the lowest values were found in summer. In contrast, the highest concentrations of most crustal elements were observed in spring, and the highest levels of pollutant elements were found in winter. Among these elements, annual mean concentrations of As and Cr exceeded WHO standard during monitoring period.

Abiotic Mixing‐Dependent Reaction in a Laboratory Simulated Hyporheic Zone

AbstractGroundwater (GW) contaminants upwelling toward surface water (SW) can attenuate in the hyporheic zone, with dissolved oxygen (DO) frequently controlling the attenuation. In a laboratory mesocosm, we induced downwelling of SW into the sediments to create a hyporheic flow cell (HFC). We added DO to downwelling SW and sodium sulfite (Na2SO3) to anoxic upwelling GW to induce an abiotic mixing‐dependent reaction along the mixing zone between the HFC and upwelling GW. Using planar optodes and SO4measurements, we observed movement of the DO mixing zone (oxic front position), extent of DO mixing (mixing zone thickness), and location of MD reaction (SO4peak concentration). Oxic front position and mixing zone thickness were stable during nonreactive control experiments, indicating that dispersion of DO across the mixing zone had come into equilibrium with supply of DO to the mixing zone. By contrast, mixing zone thickness shrank over time during the reaction experiments, as MD reaction consumed DO in the mixing zone. The decrease in mixing zone thickness for the reaction experiments indicates steeper DO gradients and greater dispersion (transport) limitation, quantified by Damköhler numbers farther above unity. Maximum SO4concentrations always occurred further from the center of the HFC (i.e., more toward surrounding upwelling GW) than did the oxic front. In most riverbeds, transport and mixing dynamics are thus superimposed upon existing hydraulic dynamics, with implications for monitoring and attenuation of contaminants.

Removal of 2,6-dichlorophenol in water by CuO activated peroxymonosulfate: Efficiency, mechanism and degradation pathway

CuO as a heterogeneous catalyst was synthesized by calcination method and characterized via various technologies. A series of metal oxides were synthesized by the same process to compare the catalytic performance. The CuO activated peroxymonosulfate (PMS) catalytic system can effectively degrade 2, 6-dichlorophenol (2,6-DCP). The effect of the calcination temperature on CuO performance was investigated, which showed that the catalytic performance was the highest at a calcination temperature of 400 °C. The effect of various factors such as catalyst dose, PMS dose, solution pH, NOM concentration and inorganic ions (Cl−, NO3−, SO42− and HCO3−) on the removal of 2, 6-DCP were probed. SO4− and OH play the predominant role for the degradation of 2, 6-DCP. According to the kinetic calculation of the quantitive experiment by nitrobenzene and benzoic acid, the generation concentrations of OH and SO4− can reach 5.92 × 10−13 mol/L and 7.92 × 10−13 mol/L, respectively. The degradation mechanism of 2, 6-DCP main including OH substitution for Cl atom, ring-opening and mineralization.

Heterogeneous catalytic oxidation degradation of BPAF by peroxymonosulfate active with manganic manganous oxide: Mineralization, mechanism and degradation pathways

In this study, the catalytic ability and mechanisms involved in activating peroxymonosulfate (PMS) with Mn3O4 and the degradation pathways of bisphenol-AF (BPAF) removal was investigated. SO4−• and ·OH which were explored by and scavenging tests were the major reactive radicals in the Mn3O4/PMS system. A simple simulation algorithm was also used to calculate the relative concentrations of SO4−• ([SO4−•]) and ·OH ([·OH]) which were 8.39 × 10 −15 M and 6.96 × 10 −13 M, respectively. The mechanism for the electron transfer between the Mn (II) and Mn (III) species was discussed. Three degradation pathways of BPAF were determined by the GC/MS and LC/MS technology, including chemical mechanism of oxidation, hydroxylation, electron transfer, polymerization, and ring-cleavage. In addition, the results suggested that the Mn3O4/PMS system had an efficient total organic carbon (TOC) removal rate and excellent environmental adaptability, the removal rate of TOC being as high as 73.2% in the control condition. Furthermore, the reuse experiments and the comparison on the structural and componential changes of Mn3O4 powder before and after reaction demonstrated that the Mn3O4 catalyst possessed excellent stability and reusability. Finally, a maximum BPAF degradation of approximately 90.0% was achieved on the optimal conditions for 500 mg/L Mn3O4 dosage, 4 mM PMS concentration, 7.0 ± 0.2 initial pH, and 5 mg/L BPAF concentration respectively. And the effect of the coexisting anions and natural environmental water quality were also considered. This study demonstrated the Mn3O4/PMS system can be considered as a green approach for the removal of environmental reluctant pollutants.

Wheat growth and nutrient uptake after phosphorus and potassium applications in saline-sodic field of semi-arid region

Nutrient deficiency is important limiting factor of saline-sodic soils which results in declining crop production in arid climates. The study investigated wheat response to phosphorus and potassium in saline-sodic field of Kohat, Pakistan. The K2O was applied at 0(K0), 75(K1), 150 (K2) kg ha-1 as K2S04 and P2O5 at (0(P0), 60(P1), 120(P2) kg ha-1 as (NH4)2HPO4 in three replications under two-factorial randomized complete block (RCB) design. Both treatments significantly enhanced wheat grain (118%) and dry matter yield (60%) at P2K2 compared to control. The P treatments significantly affected leaf P, Mg, SO4, Ca:P, SO4:P ratios and soil P, Ca:P, Cl:P and SO4:P ratios, while K on leaf K, Na, Ca, SO4concentration, K:Na, K:Ca, SO4:P,Ca:P ratios and soil pH, Na, K, Ca, SO4 concentrations, SAR, Na:K, Ca:K and Na:Ca ratios. Leaf Na was decreased to 85.3 mmol (+) kg-1 at K2 compared to 105.3 mmol (+) kg-1at P2K0. Negative correlation (R2=0.906) of leaf K:Na was found with Leaf Na concentration. Correlation of dry matter was more positive (R2=0.851) with leaf K:Na than grain yield (R2=0.392). It is concluded that K and P addition might be beneficial for improving crop nutrition and wheat yield in saline-sodic soils.

Identification of hydrogeochemical processes and transport paths of a multi-aquifer system in closed mining regions

The water quality evolution of surface water and groundwater by mining activities and closed or abandoned mines is a grave public concern around the world. To understand the characteristics of hydrogeochemical processes controlling the water quality evolution after the closure of mines, a multi-aquifer system in a closed coalfield in Huainan eastern of China was investigated as an example. Based on the results of mineral characterizations, hydrogeochemistry, and stable isotopes, carbonates minerals, gypsum, and clay minerals as well as atmosphere gases-O2, CO2, and H2O were recognized as major reactants, and evaporation, dissolution/precipitation of minerals and cation exchange were potential reactions. Using inverse geochemical modeling, three major hydrogeochemical paths in the closed mines were identified. Path1 shows that water in the closed mines is mainly recharged by the overlying Quaternary aquifer and the underlying limestone aquifers through faults and fractures, accompanied by cation exchange and sulfate reduction, making the concentrations of Na+ + K+ and HCO3− increase and the concentration of SO42− decreases along the groundwater flow path. Path 2 shows that the karst groundwater flows from the shallow (recharge) zone to the deep (circulation) zone and then flows upwards to recharge the closed mine and the Permian aquifer through faults and fractures. Along Path 2, dolomite precipitates, ion exchange, and halite dissolution mainly take place, making the concentrations of Na+ + K+ and Cl− increase and the concentration of Ca2+ and HCO3− decrease and the water chemistry type change from Ca–HCO3 type to Na + K–Cl type. Path 3 shows that waters in the mining subsidence ponds (MSPs), Huai River and Quaternary loose aquifer (QLA) are connected. Although the major elements of water in QLA still meet the drinking water guidelines of World Health Organization (WHO) and U.S. Environmental Protection Agency (USEPA), considering the fact that water in QLA is a vital drinking water source for local communities, proactive measurements should be undertaken to lower the risk of contamination of QLA by MSPs through minimizing the hydraulic connection between them. Results of this study could benefit water quality prediction and management for these complex and vulnerable systems in the study area as well as other regions of the world.

Highly efficient removal of As(III) from aqueous solutions using goethite/graphene oxide/chitosan nanocomposite

A goethite/graphene oxide/chitosan (α-FeO(OH)/GO/CS) nanocomposite adsorbent was prepared and firstly used to remove As(III) from aqueous solution. The composite was characterized by FTIR, XPS, XRD, and EDS techniques. Batch experiments were conducted to investigate the effects of several factors (initial concentration, pH, m/v, contact time, co-existing ions, and temperature) on As(III) adsorption and to evaluate adsorption kinetic, equilibrium isotherm, and thermodynamics. Results showed that As(III) adsorption increased with the increasing initial concentration, contact time, and temperature, but decreased with the increasing m/v and co-existing ions concentrations of SO42−, PO43− and Fe3+. As(III) adsorption remained high at a wide pH range of 3–10. The adsorption was well fitted to a pseudo-second-order kinetic model and was endothermic and spontaneous. The best fit of As(III) adsorption with the Freundlich and Sips models indicated that it was monolayer adsorption, and the maximum adsorption capacity was 289.42 mg/g. As(III) removal was related to -NHCO-, CO, OH, and FeO groups, but the complexation between As(III) ions and hydroxyl iron oxide was the major contributor. After the fifth desorption, the removal efficiency was still as high as 79.6%, indicating excellent reusability. Thus, this composite had great potential for removing As(III) from aqueous solutions.

Determination methods for steady-state concentrations of HO• and SO4•− in electrochemical advanced oxidation processes

Competitive kinetics and scavenging assay are commonly used for radical quantification. However, the accuracy of the two methods has been challenged in electrochemical advanced oxidation processes (EAOPs) since the strong reactivity of electrode against organic indicators may disrupt the quantitative relationship between indicator consumption and radical concentration. The present study focused on screening suitable indicators and developing suitable methods for determining the steady-state concentrations of SO4•− and HO• ([SO4•−]ss and [HO•]ss) in several EAOPs for water treatment based on competitive kinetics and scavenging assay. The applicability of the modified methods and available indicators were investigated through experimental and kinetic analysis. In anode alone process, the competitive kinetics was more appropriate than scavenging assay and benzoic acid (BA) met the basic requirement of being a competitor to determine the [HO•]ss. In cathode alone process, BA was more resistant to interfering factors than other competitors (ibuprofen, atrazine and nitrobenzene) and its reaction rate involved only the radical oxidation even when the reaction conditions varied over a wide range. Therefore, the [HO•]ss could be obtained by the competitive kinetic equation of BA when HO• existed alone. When HO• coexisted with SO4•−, a two-step method combining scavenging assay and competitive kinetics was proposed to measure [SO4•−]ss and [HO•]ss, in which tert-butyl alcohol and BA were added as scavenger and competitor, respectively. Furthermore, the reliability of each approach was verified by the experimental results and kinetic analysis.

충남 서산에서 가을에 측정한 초미세먼지의 오염 특성 조사

In this study, chemical characteristics of PM2.5 collected between October 1 and November 4, 2019 at Chungcheong region air quality research center in Seosan, were studied to understand reasons leading to PM2.5 increases. 24-hr integrated PM2.5 samples were analysed for organic and elemental carbon (OC and EC), water-soluble OC (WSOC), and eight water-soluble inorganic ions. Over the study period, increase in PM2.5 concentration was attributed to enhancement of organic mass (OM=1.8×OC) and NO₃- concentrations. Relationships of OC and WSOC with EC, K+, Cl-, and secondary NO₃- showed good-to-strong correlations, suggesting primary emissions (e.g., traffic and biomass burning sources) and secondary organic aerosol (OA) formation contributed to WSOC and OC concentrations. Moreover, high WSOC/OC (mean: 0.54) and OC/EC (mean: 9.0) ratios support the existence of various OA sources at the site. Four PM2.5 pollution episodes (October, 10 (event I), 17 (event II), 20~22 (event III), and November 02 (event IV)), which exceeded 24-hr PM2.5 Korean standard of 35 μg/m³, occurred and were related to concentration increases in OM and secondary ionic species. Based on synoptic weather patterns, PM2.5 forecast results, and air mass transport pathways, it was concluded that events I, II, and IV were significantly influenced by locally produced pollutions, while event III was impacted by both long-range transport of air pollutants and local emissions, with the highest concentration of SO₄2- (7.3 μg/m³). Among the four events, highest OM and NO₃- concentrations were found in the events IV and III, respectively. Results from this study suggest that strategies to reduce nitrogen oxides and organic aerosols in the study region are formulated to control PM2.5 levels.

Why do models perform differently on particulate matter over East Asia? A multi-model intercomparison study for MICS-Asia III

Abstract. This study compares the performance of 12 regional chemical transport models (CTMs) from the third phase of the Model Inter-Comparison Study for Asia (MICS-Asia III) on simulating the particulate matter (PM) over East Asia (EA) in 2010. The participating models include the Weather Research and Forecasting model coupled with Community Multiscale Air Quality (WRF-CMAQ; v4.7.1 and v5.0.2), the Regional Atmospheric Modeling System coupled with CMAQ (RAMS-CMAQ; v4.7.1 and v5.0.2), the Weather Research and Forecasting model coupled with chemistry (WRF-Chem; v3.6.1 and v3.7.1), Goddard Earth Observing System coupled with chemistry (GEOS-Chem), a non-hydrostatic model coupled with chemistry (NHM-Chem), the Nested Air Quality Prediction Modeling System (NAQPMS) and the NASA-Unified WRF (NU-WRF). This study investigates three model processes as the possible reasons for different model performances on PM. (1) Models perform very differently in the gas–particle conversion of sulfur (S) and oxidized nitrogen (N). The model differences in sulfur oxidation ratio (50 %) are of the same magnitude as that in SO42- concentrations. The gas–particle conversion is one of the main reasons for different model performances on fine mode PM. (2) Models without dust emission modules can perform well on PM10 at non-dust-affected sites but largely underestimate (up to 50 %) the PM10 concentrations at dust sites. The implementation of dust emission modules in the models has largely improved the model accuracies at dust sites (reduce model bias to −20 %). However, both the magnitude and distribution of dust pollution are not fully captured. (3) The amounts of modeled depositions vary among models by 75 %, 39 %, 21 % and 38 % for S wet, S dry, N wet and N dry depositions, respectively. Large inter-model differences are found in the washout ratios of wet deposition (at most 170 % in India) and dry deposition velocities (generally 0.3–2 cm s−1 differences over inland regions).

Multiple‐indicator study of the response of groundwater recharge sources to highly turbid river water after a landslide in the Tedori River alluvial fan, Japan

AbstractThe large volume of groundwater stored in the Tedori River alluvial fan, Ishikawa Prefecture, Japan, is an important source of local drinking and industrial water. The Tedori River was observed to be highly turbid from the beginning of May 2015 to at least November 2017 due to a landslide in the upper reach of the river. After the landslide, the groundwater level was drawn down by several to 10 m near the middle river section during paddy irrigation periods in 2015 and 2016. This study addresses the impacts of the highly turbid water on groundwater recharge from the river and paddy fields. In 2016, we sampled groundwater, river water, paddy irrigation water, paddy ponding water, and precipitation five times at 2‐month intervals. We analysed the H, O, and Sr stable isotopic compositions and major dissolved ion (and Sr) concentrations and compared our data to previous data obtained in June 2011. Ca, Sr, Cl, SO4, and TN concentrations and δ18O values were higher in June 2016 than in June 2011; these increases were more extreme along the left bank of the Tedori River than along the right bank. We explored the mixing of Tedori River water with groundwater using a two‐endmember mixing model based on their Sr concentrations and isotopic compositions. Compared to June 2011, mixing ratios were decreased near the Tedori River in 2016, and larger decreases were observed along the left bank and in the middle stream area. These results confirm that the contribution to groundwater recharge from the river decreased during the turbidity event, particularly along the left bank.

A novel combined treatment for pyridine waste gas using liquid absorption, catalytic ozonation, and sulfur autotrophic denitrification (LA-CO-SAD)

A novel technology, combining liquid-phase absorption, catalytic ozonation, and sulfur autotrophic denitrification (LA-CO-SAD), was proposed for the treatment of pyridine waste gas. The LA process was used to quickly fix the pyridine waste gas to attain a 500 mg/L pyridine solution. Then, catalytic ozonation was used to break the heterocyclic structure of pyridine in solution to form organic by-products and NO3−-N. After 150 min of catalytic ozonation including a MnxCu1-xO2-δ/γ-Al2O3 (x = 0.66) catalyst, pyridine was completely removed and the concentrations of total organic carbon and total nitrogen were 0 and 42.4 mg/L, respectively. All the nitrogen was in the form of NO3−-N. Long-term experiments of the catalytic ozonation process verified process stability and showed that it could completely remove biological toxicity in the solution. The remaining NO3−-N was completely removed by the SAD process within a hydraulic residence time of 2.5 h. When the experiment had run for 308 h, concentrations of SO42− in the effluent were close to 600 mg/L. Then, the effluent was discharged and the experiment was injected with fresh deionized water to start a new cycle. Compared with traditional methods, the combined technology proposed in this study has the advantages of high efficiency, stability, no secondary pollutants, and a recyclable absorbent liquid.