Photochemistry of toluene under high NOx, NH3 and humid conditions in the presence of inorganic seed particles: a smog chamber study for urban haze formation at East Asia

2020 ◽  
Author(s):  
Yong Lim ◽  
Duong Do ◽  
Hyun Jin ◽  
Jiwon Lee ◽  
Jin Young Kim
Keyword(s):  
East Asia ◽  
Ammonium Sulfate ◽  
Aqueous Phase ◽  
Thermodynamic Model ◽  
Large Fraction ◽  
Water System ◽  
Smog Chamber ◽  
High Concentration ◽  
Seed Particles ◽  
Inorganic Species

<p>High–concentration particulate matter (PM) at East Asia threatens human health and potentially alters climate. High levels of SO<sub>2</sub>, NO<sub>x</sub> and NH<sub>3</sub> emissions attribute the formation of inorganics including sulfates, nitrates and ammoniums in PM. Consequently, PM contains a large fraction of these inorganics, and aerosol liquid water (ALW) is considered to promote inorganic PM formation. A thermodynamic model has been used to estimate inorganic concentrations and a pH of PM because PM can be viewed as an ammonium-sulfate-nitrate-water system, which maintains thermodynamic equilibriums between the gas and particle phase and in the aqueous phase within particles. However, gas–particle partitioning of semivolatile inorganic species (i.e., NH<sub>3</sub>–NH<sub>4 </sub><sup>+ </sup>and HNO<sub>3</sub>–NO<sub>3</sub><sup>-</sup>) particularly influenced by organics and aqueous-phase secondary organic aerosol (aqSOA) formation in PM through multiphase chemistry are not well understood.</p><p>We conducted smog chamber experiments for OH-radical initiated reactions of toluene in the presence of ammonium sulfate seed particles under high NO<sub>x</sub>, NH<sub>3</sub> and humid conditions, which were similar to high-concentration haze conditions at Seoul, Korea. Measurements of inorganic concentrations in particles agree well with outputs of thermodynamic model simulations. The nitrate increase in seed particles is most prominent because ALW enhances the uptake of total HNO<sub>3</sub> photochemically formed from NO<sub>x</sub>. We identified methylglyoxal as a precursor for aqSOA formation. It appears that organics attribute ALW formation under deliquescence relative humidity for inorganic salts. We further investigated the response of particle mass concentrations to various NO<sub>x</sub> concentrations, which can be useful for NO<sub>x</sub> controls for PM reduction.</p>

scholarly journals Comparison of secondary organic aerosol formation from toluene on initially wet and dry ammonium sulfate particles

2017 ◽  
Author(s):  
Tengyu Liu ◽  
Dan Dan Huang ◽  
Zijun Li ◽  
Qianyun Liu ◽  
ManNin Chan ◽  
...  
Keyword(s):  
Ammonium Sulfate ◽  
Functional Groups ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Seed Particles ◽  
The Difference ◽  
Wet Particles

Abstract. The formation of secondary organic aerosol (SOA) has been widely studied in the presence of dry seed particles at low relative humidity (RH). At higher RH, seed particles can exist as dry or wet particles. Here, we investigated the formation of SOA from the photooxidation of toluene using an oxidation flow reactor under a range of OH exposures on initially wet or dry ammonium sulfate (AS) seed particles at an RH of 68 %. At an OH exposure of 4.66 × 1010 molecules cm -3 s, the ratio of the SOA yield on wet AS seeds to that on dry AS seeds was 1.31 ± 0.02. However, this ratio decreased to 1.01 ± 0.01 at an OH exposure of 5.28 × 1011 molecules cm -3 s. The decrease in the ratios of SOA yields as the increase of OH exposure may be due to the early deliquescence of initially dry AS seeds after coated by highly oxidized toluene-derived SOA. SOA formation lowered the deliquescence RH of AS and resulted in the uptake of water by both AS and SOA. Hence the initially dry AS seeds contained aerosol liquid water (ALW) soon after a large fraction of SOA formed and the SOA yield and ALW approached those of the initially wet AS seeds as OH exposure and ALW increased. However, a higher oxidation state of the SOA on initially wet AS seeds than that on dry AS seeds was observed at all levels of OH exposure. The difference in mass fractions of m/z 29, 43 and 44 of SOA mass spectra indicated that SOA formed on initially wet seeds may be enriched in earlier-generation products containing carbonyl functional groups at low OH exposures and later-generation products containing acidic functional groups at high exposures. Our results suggest that AS dry seeds soon turn to at least partially deliquesced particles during SOA formation and more studies on the interplay of SOA formation and ALW are warranted.

Arsenic Contamination and its Speciation in the Water System around the Abandoned Dongil Au-Ag Mine in Korea

2005 ◽  
Vol 277-279 ◽  
pp. 503-509 ◽  
Author(s):  
Ji Min Yi ◽  
Jin Soo Lee ◽  
Hyo Taek Chon
Keyword(s):  
Stream Water ◽  
Arsenic Concentration ◽  
Water System ◽  
Arsenic Species ◽  
High Concentration ◽  
Aqua Regia ◽  
Sequential Extraction Analysis ◽  
Fe Oxyhydroxides ◽  
High Level ◽  
Stream Waters

This study was made to investigate the extent and degree of As contamination in waters and sediments influenced by previous mining activity in the abandoned Dongil Au-Ag mine. Arsenic species was also identified in surface waters and groundwater. The chemical form of As in sediments was examined using sequential extraction analysis. The major contamination source of As in the mine area is suggested to be tailings with elevated levels of 8,718 As mg/kg. This was associated with the release of high level of As into the water system in the study area. The pH values of water samples ranged from 7.7 to 10.1, which was neutral to strong alkaline due to buffering effect by high concentration of Ca and Mg dissolved from carbonate mineral and weathering of concrete. Stream waters contained high level of As within the range of 40.5 to 150.4 ㎍/L and most waters exceeded the permissible level (50 ㎍/L) of As for stream water in Korea. The concentration ratios of As(Ⅲ) to As (total), however, extended in the range of 5.8 to 75% and increased at low pH condition in stream waters. Arsenic concentration in sediments digested by aqua regia (HNO3+HCl) ranged from 162 to 2,077 mg/kg. The highest concentration of As may be due to the direct inflow of tailings. The relatively high percentage (17.1~35.3%) of As coprecipitated with amorphous Fe oxyhydroxides indicates that more severe contamination of As can occur by re-extracting due to changes of chemical environment such as reducing condition.

The distribution coefficients of phenol and substituted phenols in the ammonium sulfate-poly-N-vinylpyrrolidone-water system

2011 ◽  
Vol 85 (4) ◽  
pp. 568-572 ◽  
Author(s):  
E. V. Churilina ◽  
P. T. Sukhanov ◽  
Ya. I. Korenman ◽  
A. N. Il’in ◽  
G. V. Shatalov ◽  
...  
Keyword(s):  
Ammonium Sulfate ◽  
Water System ◽  
Distribution Coefficients ◽  
Substituted Phenols

Assessment of Phytoplankton Nutrient Limitation in Productive Waters: Application of Dilution Bioassays

1993 ◽  
Vol 50 (10) ◽  
pp. 2208-2221 ◽  
Author(s):  
Hunter J. Carrick ◽  
Claire L. Schelske ◽  
Frederick J. Aldridge ◽  
Michael F. Coveney
Keyword(s):  
Large Fraction ◽  
Nutrient Concentrations ◽  
Nutrient Loads ◽  
Nutrient Reduction ◽  
High Concentration ◽  
Phytoplankton Assemblages ◽  
Lake Apopka ◽  
P Limitation ◽  
Management Scheme ◽  
Total P

Excessive nutrient loads to aquatic systems can complicate otherwise predictable relationships between nutrient concentrations and phytoplankton biomass. We conducted six bioassays on surface phytoplankton assemblages collected from productive Lake Apopka, Florida, to measure the effect of nutrient reduction on phytoplankton growth and nutritional state. Lake water was mixed with one of three diluents to create a gradient of ambient nutrient concentrations; nitrogen (N) and phosphorus (P) limitation at each level of dilution was evaluated in a 2 × 2 factorial design. While the addition of N clearly increased the growth of phytoplankton in undiluted Lake Apopka water, the phytoplankton became more P limited with the reduction of particles (30–60% dilution). Regression of algal yields onto total P concentrations from our bottle experiments indicated that an 8 μg∙L−1 change in P leads to only a 1 μg∙L−1 change in chlorophyll yield, probably due to the high concentration of P in the lake. Because dilution influences factors in addition to ambient nutrient concentrations, results obtained with the technique must be carefully evaluated. Despite this, reduction of particles to improve water quality may, in concept, be a reasonable management scheme in lakes where a large fraction of the nutrients is particulate.

Modelling of microbial processes that govern degradation of organic substrates in soil, with special reference to pesticides

1990 ◽  
Vol 329 (1255) ◽  
pp. 369-373 ◽  
Keyword(s):  
Microbial Population ◽  
Large Fraction ◽  
Organic Substrates ◽  
High Concentration ◽  
Deterministic Models ◽  
Soil Microbial ◽  
Low Concentrations ◽  
Biokinetic Parameters ◽  
Soil Microbial Population ◽  
Kinetics Of

We tried to develop deterministic models for kinetics of 2,4-D breakdown in the soil based on the following considerations: (i) at low concentrations degradation results from maintenance consumption by a large fraction of the soil microbial population; (ii) at high concentration in addition to the maintenance consumption there is a growth-associated carbon incorporation by a small specific microbial population. Values for the biokinetic parameters are consistent with those commonly found in the literature. Comparison between observed and simulated curves suggests that a non-negligible part of the pesticidal carbon exists as microbial by-products.

scholarly journals Degradation of Metaldehyde in Aqueous Solution by Nano-Sized Photocatalysts and Granular Activated Carbon

2020 ◽  
Vol 20 (7) ◽  
pp. 4505-4508
Author(s):  
Jong Kyu Kim ◽  
Tingting Jiang ◽  
Zhoujun Li ◽  
Suseeladevi Mayadevi ◽  
Kale Bharat ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Water System ◽  
Granular Activated Carbon ◽  
Quality Standard ◽  
High Concentration ◽  
Degradation Rates ◽  
Drinking Water System ◽  
Ultraviolet Light Irradiation ◽  
Nitrogen Doped Titanium Dioxide

Metaldehyde has been detected in drinking water system in relatively high concentration exceeding European water quality standard. In order to address this problem, the aim of this project was to treat metaldehyde aqueous solution by advanced oxidation processes (AOPs) and granular activated carbon (GAC) column. Ten novel materials were tested for degradation rates of metaldehyde under ultraviolet light irradiation (UVC). For treatment of 1 mg/L metaldehyde solution by AOPs, the highest degradation rate is 16.59% under UVC light with the aid of nitrogen doped titanium dioxide coated graphene (NTiO2/Gr). Furthermore, 0.5 mg/L is the optimal concentration for degradation of metaldehyde with N–TiO2/Gr under UVC light. Apart from that, the lifetime of GAC column could be elongated on condition that metaldehyde has been treated by AOPs previously. Hence, combination of AOPs and GAC column is promising in treating water containing metaldehyde.

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