Causal impact analysis of weir opening on cyanobacterial blooms and water quality in the Yeongsan River, Korea: A bayesian structural time-series analysis and median difference test.

The construction of weirs in Korea's Four Major Rivers Project has led to an increase in cyanobacterial blooms, posing environmental challenges. To address this, the government began opening weirs in 2017. However, interpreting experimental results has proven to be complex due to the multifaceted nature of blooms.

Causal impact analysis of enhanced phosphorus effluent standard on river water quality.

The effect of environmental policies on water quality is an important factor in evaluating a project's impact and economic feasibility. The aim of this study was to evaluate the causal relationship between strengthening the total phosphorus (TP) concentration standard in wastewater treatment plant (WWTP) effluents and river water quality in the Geum River watershed (Rep. of Korea).

Variability of pCO in surface waters and development of prediction model.

Inland waters are substantial sources of atmospheric carbon, but relevant data are rare in Asian monsoon regions including Korea. Emissions of CO to the atmosphere depend largely on the partial pressure of CO (pCO) in water; however, measured pCO data are scarce and calculated pCO can show large uncertainty. This study had three objectives: 1) to examine the spatial variability of pCO in diverse surface water systems in Korea; 2) to compare pCO calculated using pH-total alkalinity (Alk) and pH-dissolved inorganic carbon (DIC) with pCO measured by an in situ submersible nondispersive infrared detector; and 3) to characterize the major environmental variables determining the variation of pCO based on physical, chemical, and biological data collected concomitantly.

Occurrence of micropollutants in four major rivers in Korea.

There has been an increasing concern in recent years over the presence of numerous micropollutants in river water. Simultaneously, risk assessment of micropollutants has become increasingly important due to their high toxicity. Therefore, the aims of this study were to characterize the levels of micropollutants in rivers, to identify the sources of these pollutants, and to evaluate their risk quotients (RQ) to the ecological system.

Prediction of the fate and transport processes of atrazine in a reservoir.

The fate and transport processes of a toxic chemical such as atrazine, an herbicide, in a reservoir are significantly influenced by hydrodynamic regimes of the reservoir. The two-dimensional (2D) laterally-integrated hydrodynamics and mass transport model, CE-QUAL-W2, was enhanced by incorporating a submodel for toxic contaminants and applied to Saylorville Reservoir, Iowa. The submodel describes the physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical.

The effect of hydrodynamic flow regimes on the algal bloom in a monomictic reservoir.

The effectiveness of a proposed curtain weir to be installed in the transitional zone of a eutrophic reservoir located in monsoon areas on the control of algal blooms in the lacustrine zone where drinking water withdrawals occur was assessed with various hydrodynamic flow regimes. A two-dimensional hydrodynamic and eutrophication model that can accommodate vertical displacement of the weir following the water surface changes was developed and validated using field data obtained from two distinctive hydrological years; drought (2001) and wet (2004). The model adequately reproduced the temporal and spatial variations of temperature, nutrients and phytoplankton concentrations in the reservoir.

Airways are more reactive to histamine than to methacholine in patients with mild airway hyperresponsiveness, regardless of atopy.

Background: The airway muscles from allergen-sensitized animals in vitro show a heightened response to histamine, but not to carbachol. This study investigated whether the airway responsiveness to histamine in vivo is comparable to that of methacholine in human subjects with varying degrees of atopy.

Methods: One-hundred-and-sixty-eight consecutive adult asthma patients or volunteers underwent bronchoprovocation tests to both histamine and methacholine after determining their blood eosinophil counts, serum total IgE levels and skin test reactivity to 10 common aeroallergens.

Water quality of runoff from agricultural-forestry watersheds in the Geum River Basin, Korea.

Forestry and agricultural land uses constitute 85% of Korea and these land uses are typically mixed in many watersheds. Land cover is one of the most important factors affecting diffuse pollution and water quality. The aim of this study is to estimate the pollutant concentrations in runoff from four study watersheds consisting of a mix of forestry and agricultural land uses at different ratios in the Geum River Basin.

Airway hyperresponsiveness to hypertonic saline as a predictive index of exercise-induced bronchoconstriction.

Background: Changes in airway mucosal osmolarity are an underlying mechanism of bronchoconstrictive responses to exercise and hypertonic saline (HS). The purpose of this study was to examine whether an osmotic challenge test using HS can predict exercise-induced bronchospasm (EIB) in asthma patients.

Methods: Thirty-six young male asthmatic patients underwent bronchial challenge tests based on 4.

Effects of anti-asthma therapy on dyspnea perception in acute asthma patients.

Blunted perception of dyspnea may predispose patients to fatal asthma attacks. To examine whether this impaired perception of dyspnea in patients with acute asthma could be corrected by anti-asthma therapy, the medical records of 104 consecutive asthma patients who had been hospitalized as a result of asthma attacks were analyzed retrospectively. During the course of treatment with conventional asthma medications, the forced expiratory volume in 1s (FEV1) and the Borg scale-based dyspnea perception scores during breathing through an inspiratory muscle trainer were measured at least twice.

Increased releasability of skin mast cells after exercise in patients with exercise-induced asthma.

The role of lung mast cells in exercise-induced asthma (EIA) is controversial. To investigate whether the skin mast cell releasability is increased after exercise in EIA, 49 young atopic men with or without asthma took part in a free-running test for 6 min and were given skin prick tests using morphine, a mast cell secretagogue, before and after the exercise. The mean diameters of the wheal induced by morphine in patients with EIA were not significantly different from those in patients without EIA before exercise, although the baseline lung function was significantly lower and the airway hyperresponsiveness, the peripheral blood eosinophil count, and the size of the wheal in response to Dermatophagoides pteronyssinus were significantly higher in patients with EIA.

Late local urticaria as a long-term sequela of allergen-specific immunotherapy.

Local reaction to allergen-specific immunotherapy (SIT) usually appears within 30 minutes, but cases with exercise-induced urticaria at the SIT site 2-3 weeks after the last allergen injection have been reported. A 28-year-old man was treated with house dust mite-SIT for 5 years, due to asthma when he was an 11-year-old boy. On a treadmill exercise test for 50 minutes, erythema, swelling, and pruritus occurred at the SIT site, which lasted for one hour.

A two-dimensional model for simulating the transport and fate of toxic chemicals in a stratified reservoir.

A two-dimensional reservoir toxics model is essential to establishing effective water resources management and protection. In a reservoir, the fate of a toxic chemical is closely connected with flow regimes and circulation patterns. To better understand the kinetic processes and persistence and predict the dissipation of toxic contaminants in the reservoir during a spill or storm runoff event, a toxics submodel was developed and incorporated into an existing laterally integrated hydrodynamics and transport model.