Nitrate-driven high PM2.5 episodes in Seoul during pre-monsoon season

Abstract

<p>Ammonium nitrate (NH<sub>4</sub>NO<sub>3</sub>) is the main driver of high PM<sub>2.5</sub> episodes in Seoul, but its formation processes are not fully understood yet. Intensive experiments were conducted at the Korea University campus in Seoul during June ~ August 2018 and April ~ June 2019, when the chemical composition of PM<sub>2.5</sub> including Na<sup>+</sup>, SO<sub>4</sub><sup>2-</sup>, NH<sub>3</sub>, NO<sub>3</sub><sup>-</sup>, Cl<sup>-</sup>, Ca<sup>2+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, OC and EC, and its gaseous precursors including NO<sub>X</sub>, HNO<sub>3</sub> and SO<sub>2</sub> were continuously measured. The concentrations of PM<sub>2.5</sub> and its major constituents were noticeably higher in pre-monsoon (June) than summer monsoon (July~August) period. In particular, nitrate concentration was much higher (6.9 μg/m<sup>3</sup>) during the high PM<sub>2.5</sub> episode (24-hr average PM<sub>2.5</sub> > 35 μg/m<sup>3</sup>) in June compared to those of non-episode (3.1 μg/m<sup>3</sup>) and the other two months (0.74 μg/m<sup>3</sup>). Aerosol liquid water content (ALWC) was calculated using ISORROPIA II model, ALWC was higher during the episode than non-episode and the highest ALWC was found concurrently with the highest NO<sub>3</sub><sup>-</sup> concentration (18.2 μg/m<sup>3</sup>) at night. Concurrent increases of nitrate and ALWC cause aqueous-phase formation and hygroscopic growth of aerosol, which lead to high PM<sub>2.5</sub> concentration. In addition, ALWC was more rapidly increased with the number of accumulation mode particles larger than 100 nm in diameter at higher RH and nitrate concentration. In this study, PM<sub>2.5</sub> mass and nitrate were elevated after the NO<sub>X</sub> peak in the morning as well as at dawn. The surface of pre-existing particles was found to be prerequisite for nitrate driven PM<sub>2.5</sub> episode.</p>

The Effect of Stress on Compulsive Sexual Behavior Disorder: Active Coping Strategy and Self-Control as Mediators

“…Participants at higher risk for compulsive sexual behavior, like other addicts, feel shame. In order to escape this shame, the addiction is reenacted, the shame worsens, and the cycle is repeated [ 3 ]. Most addicts exhibit periodic cycles of immersion, habitual behavior or consciousness, obsessive sexual behavior, and despair to relieve their psychological distress [ 3 ].…”

“…In order to escape this shame, the addiction is reenacted, the shame worsens, and the cycle is repeated [ 3 ]. Most addicts exhibit periodic cycles of immersion, habitual behavior or consciousness, obsessive sexual behavior, and despair to relieve their psychological distress [ 3 ]. The first phase of immersion is a desperate and anxious search for objects that have been effective in avoiding and neutralizing psychological pain, sexually romantic fantasies, and sexual pleasure.…”

“…In the third stage, the obsessive sexual activity is carried out as planned, and sexual pleasure is at its zenith and out of control, which will make the addiction worse. Fourth, they feel guilty after their addictive behavior, and to reduce this feeling, another sexual behavior is pursued [ 3 ].…”

“…For Participants at higher risk for compulsive sexual behavior, sexual acts serve as rewards or benefits that can relieve stress because they seek compensation, such as relieving stress or tension, through sexual activity [ 6 ]. When a Participants at higher risk for compulsive sexual behavior suffers from life stress, he or she finds a partner who can help relieve his sexual desire and feel comfort and relief after it is resolved [ 3 , 6 ]. This feel comfort and relief give Participants at higher risk for compulsive sexual behavior a more positive experience than control [ 7 ].…”

The Primary Process and Key Concepts of Economic Evaluation in Healthcare

“…According to the method for calculating each alternative’s total effect and cost, economic evaluations can be divided into trial-based and model-based economic evaluations [ 20 ]. The latter type uses decision-analytic models, which can be classified into several types based on whether the model is static or dynamic and whether the simulation is performed at the population-level or at the individual-level ( Table 2 ).…”