Jeonghoon Lee

Nitrate contamination in stream water and groundwater is a serious environmental problem that arises in areas of high agricultural activities or high population density. It is therefore important to identify the source and flowpath of nitrate in water bodies. In recent decades, the dual isotope analysis (δ15N and δ18O) of nitrate has been widely applied to track contamination sources by taking advantage of the difference in nitrogen and oxygen isotope ratios for different sources. However, trans

We report a study of solute transport in snow, using artificial rain‐on‐snow experiments with conservative anions (F − , Br − , and SO 4 2− ). The tracers were mixed into tap water and sprayed onto the snow surface from two water supply tanks. The water flux out of the base of the snowpack was recorded, and discharge samples were collected and analyzed for the three tracers. The chemical concentration of tracers in the discharge was negatively associated with the water flux. The objectives of th

An automated proteolytic digestion bioreactor and droplet deposition system was constructed with a plastic microfluidic device for off-line interfacing to matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The microfluidic chips were fabricated in poly(methyl methacrylate) (PMMA), using a micromilling machine and incorporated a bioreactor, which was 100 microm wide, 100 microm deep, and possessed a 4 cm effective channel length (400 nL volume). The chip

Abstract. We examine the co-variations of tropospheric water vapor, its isotopic composition and cloud types and relate these distributions to tropospheric mixing and distillation models using satellite observations from the Aura Tropospheric Emission Spectrometer (TES) over the summertime tropical ocean. Interpretation of these process distributions must take into account the sensitivity of the TES isotope and water vapor measurements to variations in cloud, water, and temperature amount. Conse

Groundwater salinization in coastal aquifers because of seawater intrusion has raised serious concerns worldwide since it deteriorates the quality of drinking water and thereby threatens sustainable economic development. In particular, this problem has been a cause of growing concern in the western coastal regions of South Korea. In this paper, we review studies of seawater intrusion in western coastal regions of South Korea conducted over the past 20 years, particularly focusing on studies repo

Isotopic variations of snowmelt provide important information for understanding snowmelt processes and the timing and contribution of snowmelt to catchments in spring. We report a new model for simulating the isotopic evolution of snowmelt. The model includes a hydraulic exchange between mobile and immobile water, and an isotopic exchange between liquid water (mobile and immobile water) and ice within a snowpack. Since this model is based on the mobile‐immobile water conceptualization, which is

Tropical rainforests are known to exhibit low intraseasonal precipitation variability compared with oceanic areas with similar mean precipitation in observations and models. In the present study, the potential role of transpiration for this difference in precipitation variability is investigated using the National Center for Atmospheric Research (NCAR) atmospheric general circulation model. Comparing model results with and without transpiration shows that in the absence of transpiration, mean pr

The effect of seawater on the groundwater in archipelago of South Korea where it has rarely been investigated was analyzed by examining the hydrogeochemical characteristics. A total of 74 groundwater samples were classified by water quality type and Cl−/HCO3− molar ratio. First, 36 samples of the Ca–Cl type and 32 samples of the Na–Cl type (accounting for 91.9% of the total) were considered to have been influenced by seawater. When the samples had been classified based on the Cl−/HCO3− molar rat

The proof of principle for high-resolution analysis of intact singly charged proteins of any size is presented. Singly charged protein ions were produced by electrospray ionization followed by surface-induced charge reduction at atmospheric pressure. The inlet and trapping system "stops" the forward momentum of the protein ions over a very broad range to be captured by the digitally produced electric fields of a large radius linear ion trap whereupon they are moved into a smaller radius linear i