이수현 Su-hyeon Lee , 권수민 Su-min Kwon , 황선진 Sun-jin Hwang

DOI:10.15681/KSWE.2023.39.6.433 Vol.39(No.6) 433-438, 2023

This study investigated the growth and metabolic characteristics of Arthrospira platensis (A. platensis) according to pH, which has an alkaline optimal pH. The intake of inorganic carbon was expected to be the highest at the optimum pH 9, but it was different from the expectation, so the cause of the excessive intake of inorganic carbon at pH 7 was investigated. We tried to verify the triacylglycerol (TAG) synthesis metabolic mechanism because it was assumedthat the inorganic carbon intake of A. platensis according to pH is closely related to lipid production inside the cell. To verify this, the effects of pH on inorganic carbon intake were examined through lipid analysis inthe cell of A. platensis according to pH. As a result, in the case of the effect of inorganic carbon intake of A. platensis according to pH on TAG content, pH 9 and pH 11 showed no significant difference in TAG content, but at pH 7, it was two times higher compared to pH 9 and pH 11. It was assumed that the reason why A. platensis excessively consumed inorganic carbon at pH 7 was because itincreased the TAG content in proportion to the intake of inorganic carbon to protect cells from external pH stress. In addition, it is considered that the TAG content produced in proportion to the intake of inorganic carbon is because acetyl-CoA produced in the Calvin cycle is required for the synthesis of TAG.

Arthrospira platensis, Inorganic carbon uptake, Nile red, pH stress, TAG content

오혜연 Hye Yeon Oh , 김은정 Eun Jung Kim , 최정현 Jung Hyun Choi

DOI:10.15681/KSWE.2023.39.6.439 Vol.39(No.6) 439-450, 2023

The Yeongsan River, a major water resource for Jeollanam-do, that is adjacent to industrial complexes and agricultural areas, is exposed to water pollution. Therefore, it is necessary to investigate the impact of water pollution incidences and prepare response systems for river environment safety for other water resources in the future. Environmental Fluid Dynamics Code (EFDC) was applied to the mainstream of the Yeongsan River where residential, commercial, and agricultural areas are located to analyze the behavior of pollutants conducting the scenario analysis. Considering the pollutants that affected the study area, two pollutants, oil and benzene, with different physical and chemical characteristics were selected for the analysis. As a result of comparing the actual and simulated values of the water elevation, temperature, and flow rate, it was confirmed that the model adequately reproduced the hydraulic characteristics of the Yeongsan River. The oil flow dynamics showed that an increase in flow rate led to reduction in the maximum height of the slick. Notably, the behavior of the oil was predominantly influenced by the wind conditions. In the case of benzene, lower flow scenarios exhibited decreased arrival times and residence times accompanied by an elevation in the maximum concentration levels. From the results of pollutant behavior in the study area, it is feasible to utilize the section of tributary confluence for collection and the weir area for dilution. This study enhances the understanding of the pollutant’s behavior with different characteristics and develops effective control systems tailored to the physicochemical attributes of pollutants.

Chemical spill, Environmental Fluid Dynamics Code Plus (EFDC+), Oil spill, Pollution response, Yeongsan River

김효진 Hyo-jin Kim , 김민경 Min-kyeong Kim

DOI:10.15681/KSWE.2023.39.6.451 Vol.39(No.6) 451-464, 2023

Harmful cyanobacterial monitoring is time-consuming and requires skilled professionals. Recently, Phycocyanin, the accessory pigment unique to freshwater cyanobacteria, has been proposed as an indicator for the presence of cyanobacteria, with the advantage of rapid and simple measurement. The purpose of this research was to evaluate the correlation between the harmful cyanobacterial cell density and the concentration of phycocyanin and to consider how to use the real-time water quality monitoring system for algae bloom monitoring. In the downstream of the Nakdong River, Microcystis spp. showed maximum cell density (99 %) in harmful cyanobacteria (four target genera). A strong correlation between phycocyanin(measured in the laboratory) concentrations and harmful cyanobacterial cell density was observed (r = 0.90, p ˂ 0.001), while a weaker relationship (r = 0.65, p ˂ 0.001) resulted between chlorophyll a concentration and harmful cyanobacterial cell density. As a result of comparing the phycocyanin concentration (measured in submersible fluorescence sensor) and harmful cyanobacterial cell density, the error range increased as the number of cyanobacteria cells increased. Before opening the estuary bank, the diurnal variations of phycocyanin concentrations did not mix by depth, and in the case of the surface layer, a pattern of increase and decrease over time was shown. This study is the result of analysis when Microcystis spp. is dominant in downstream of Nakdong River in summer, therefore the correlation between the harmful cyanobacteria density and phycocyanin concentrations should be more generalized through spatio-temporal expansion.

Harmful cyanobacteria, Nakdong River, Phycocyanin, Real-time measurement

김보영 Bo Young Kim , 정가영 Ka-young Jung , 허진 Jin Hur

DOI:10.15681/KSWE.2023.39.6.465 Vol.39(No.6) 465-474, 2023

The chemical composition and molecular weight characteristics of dissolved organic matter (DOM) exert a profound influence on the efficiency of organic matter removal in water treatment systems, acting as efficiency predictive indicators. This research evaluated the primary chemical and molecular weight properties of DOM derived from diverse sources, including rivers, lakes, and biomasses, and assessed their relationship with the efficiency of coagulation/flocculation treatments. Dissolved organic carbon (DOC) removal efficiency through coagulation/flocculation exhibited significant correlations with DOM's hydrophobic distribution, the ratio of humic-like to protein-like fluorescence, and the molecular weight associated with humic substances (HS). These findings suggest that the DOC removal rate in coagulation/flocculation processes is enhanced by a higher presence of HS in DOM, an increased influence of externally sourced DOM, and more presence of high molecular weight compounds. The results of this study further posit that the efficacy of water treatment processes can be more accurately predicted when considering multiple DOM characteristics rather than relying on a singular trait. Based on major results from this study, a predictive model for DOC removal efficiency by coagulation/flocculation was formulated as: 24.3 - 7.83 × (fluorescence index) + 0.089 × (hydrophilic distribution) + 0.102 × (HS molecular weight). This proposed model, coupled with supplementary monitoring of influent organic matter, has the potential to enhance the design and predictive accuracy for coagulation/flocculation treatments targeting DOC removal in future applications.

Coagulation/Flocculation, Dissolved Organic Matter(DOM), Fluorescence, Hydrophobic, Molecular Weight, Multiple regression equation

정봉준 Bongjun Jung , 공동수 Dongsoo Kong

DOI:10.15681/KSWE.2023.39.6.475 Vol.39(No.6) 475-490, 2023

Chemical water quality suitability for species (Ephemera strigata, Ephemera separigata, and Ephemera orientalis-sachalinensis group) of the mayfly genus Ephemera (Order Ephemeroptera) was analyzed with probability distribution models (Exponential, Normal, Lognormal, Logistic, Weibull, Gamma, Beta, Gumbel). Data was collected from 23,957 sampling units of 6,664 sites in Korea from 2010 to 2021. E. orientalis-sachalinensis occurred at the range of BOD₅ 0.3~11.1 mg/L (the best-fit Lognormal model); T-P 0.007~0.769 mg/L (the Gumbel model); TSS 0.4~142.2 mg/L (the Lognormal model). E. strigata occurred at the range of BOD₅ 0.4~7.4 mg/L (the Gumbel model); T-P 0.007~0.254 mg/L (the Lognormal model); TSS 0.4~17.1 mg/L (the Lognormal model). E. separigata occurred at the range of BOD₅ 0.4~2.6 mg/L (the R-Weibull model); T-P 0.007~0.134 mg/L (the Lognormal model); TSS 0.7~10.0 mg/L (the Lognormal model). Habitat suitability range of E. orientalis-sachalinensis was estimated to be 0.4~1.9 mg/L (BOD₅), 0.024~0.086 mg/L (T-P), 2.5~22.4 mg/L (TSS); that of E. strigata was 0.4~0.7 mg/L (BOD₅), 0.007~0.018 mg/L (T-P), 0.0~1.7 mg/L (TSS); that of E. separigata was 0.0~0.4 mg/L (BOD₅), 0.000~0.015 mg/L (T-P), 0.5~3.1 mg/L (TSS). In a relative comparision, E. orientalis-sachalinensis was estimated to be eurysaprobic, and narrowly adapted in high levels of T-P and TSS, E. strigata was estimated to be oligosaprobic and adapted in low levels of T-P and TSS, and E. separigata was estimated to be stenooligosaprobic and widely adapted in low level of T-P and TSS.

Chemical water quality, Ephemera, Eurysaprobic, Habitat suitability index, Oligosaprobic, Stenooligosaprobic