김유흔 Yu-Heun Kim , 이혜원 Hye-won Lee , 최정현 Jung-Hyun Choi

DOI:10.15681/KSWE.2022.38.1.1 Vol.38(No.1) 1-9, 2022

The Yeongsan River, one of the four major rivers in Korea, shows the highest degree of water pollution compared to the other major rivers. The construction and opening of two weirs, Seungchon and Juksan, induced fluctuations in the hydrologic conditions and water quality of the river. To investigate the water quality changes caused by the opening of the weir in 2017, this study analyzed the water quality data using the non-parametric Wilcoxon signed-rank test and the three-dimensional spatiotemporal plots. The non-parametric statistical test results showed that the concentration of all parameters has increased after 2017 at a significance level of 0.05. For the parameters that showed the highest degree of change, chlorophyll-a and suspended solids, the median values have increased by more than 30% after weir opening. Visual analysis additionally showed the spatial changes in the Yeongsan River. Generally, the sites above the Seungchon weir showed higher pollution levels than those above the Juksan weir. In time series, visual analysis results also showed the trend of rising concentration for all water quality parameters, indicating that the opening of two weirs had a significant effect on the change in water quality of the Yeongsan River.

Non-parametric test, Spatiotemporal plot, Water quality, Weir, Yeongsan River

배효진 Hyojin Bae , 정성욱 Sungwook Choung , 정진아 Jina Jeong

DOI:10.15681/KSWE.2022.38.1.10 Vol.38(No.1) 10-18, 2022

This study was conducted to investigate the effect of soil and groundwater environment changed by wildfire on cesium adsorption and transport. Soil samples (A, B) used in the study were collected from Gangwon-do, where wildfires frequently occur, and the adsorption and transport of cesium in the samples were evaluated through batch and column experiments. As a result of the batch adsorption experiments with various concentrations of cesium (CW ≈ 10~10⁵ μg/L), the adsorption distribution coefficient (K_d) of cesium was higher in sample A for all observed concentrations. It means that the adsorption capacity of sample A was higher to that of sample B, which was also confirmed through the parameters of adsorption isotherm models (Freundlich and Langmuir model) applied to the experimental results. The fixed bed column experiments simulated the actual soil and groundwater environment, and they showed that cesium was retarded approximately 43 and 27 times than a nonreactive tracer in sample A and B, respectively. In particular, a significant retardation occurred in the sample A. Although sample A contains little clays, total organic carbon (TOC) contents were 3 times greater than sample B. These results imply that particulate organic matter caused by wildfire might influence the adsorption and transport of cesium in the organic matter-rich soil and groundwater environment.

Adsorption, Organic matter, Radiocesium, Retardation, Wildfire

김민희 Minhee Kim , 이정희 Junghee Lee , 성경희 Kyounghee Sung , 임철수 Cheolsoo Lim , 황원재 Wonjae Hwang , 현승훈 Seunghun Hyun

DOI:10.15681/KSWE.2022.38.1.19 Vol.38(No.1) 19-30, 2022

Climate change has increased the average air temperature. Rising air temperature are absorbed by water bodies, leading to increasing water temperature. Increased water temperature will cause eutrophication and excess algal growth, which will reduce water quality. In this study, long-term trends of air and water temperatures in the Han-river basin over the period of 1997-2020 were discussed to assess the impacts of climate change. Future (∼2100s) levels of air temperature were predicted based on the climate change scenarios (Representative concentration pathway (RCP) 2.6, 4.5, 6.0, and 8.5). The results showed that air and water temperatures rose at an average rate of 0.027°C year^-1 and 0.038°C year^-1 respectively, over the past 24 years (1997 to 2020). Future air temperatures under RCP 2.6, 4.5, 6.0, and 8.5 increased up to 0.32°C 1.18°C, 2.14°C, and 3.51°C, respectively. An increasing water temperature could dissolve more minerals from the surrounding rock and will therefore have a higher electrical conductivity. It is the opposite when considering a gas, such as oxygen, dissolved in the water. Water temperature also governs the kinds of organisms that can live in rivers and lakes. Fish, insects, zooplankton, phytoplankton, and other aquatic species all have a preferred temperature range. As temperatures get too far above or below this preferred range, the number of individuals of the species decreases until finally there are none. Therefore, changes of water temperature that are induced by climate change have important implications on water supplies, water quality, and aquatic ecosystems of a watershed.

Climate change, Future air temperature, Han-River basin, Water quality, Water temperature

이윤경 Lee Yun Kyung , 허진 Hur Jin

DOI:10.15681/KSWE.2022.38.1.31 Vol.38(No.1) 31-42, 2022

Dissolved organic matter (DOM), which changes according to various factors, is ubiquitously present from natural environments to engineered treatment systems. Only limited information is available regarding the environmental functions of DOM after bulk analyses are only applied for characterization. In this paper, latest DOM analytical techniques are briefly introduced, which include fluorescence excitation-emission matrix with parallel factor analysis (EEM-PARAFAC), size-exclusion chromatography with an organic carbon detector (SEC-OCD), carbon/nitrogen stable-isotope ratio, and Fourier transform-ion cyclotron resonance-mass spectroscopy (FT-ICR-MS). Recent examples of using advanced analyses to interpret the phenomena associated with DOM occurring in natural and engineered systems are presented here. Through EEM-PARAFAC, different components like protein-like, fulvic-like, and humic-like can be identified and tracked individually through the investigated systems. SEC-OCD allows researchers to quantify different size fractions. FT-ICR-MS provides thousands of molecular formulas present in bulk DOM samples. Lastly, carbon/nitrogen stable-isotope ratio offers reasonable tools for tracking the sources in environments. We also discuss the advantages and weakness of the above-mentioned characterizing tools. Specifically, they focus on single environmental factors (different sourced-DOM and interaction of sediment-pore water) or simple changes after individual treatment processes. Through collaboration with the advanced techniques later, they help the researchers to better understand environmental behaviors in aquatic systems and serve as essential tools for addressing various pending problems associated with DOM.

Dissolved organic matter, Fluorescence EEM-PARAFAC, Fourier transform ion cyclotron resonance mass spectroscopy, Molecular size distribution, Stable isotope ratio