Rainfall and Water Quality Characteristics of Saemangeum Area

Monica, Nankya,Choi, Kyung-Sook Institute of Agricultural Science and Technology 2014 慶北大農學誌 Vol.32 No.4

This study investigated characteristics of rainfall and water quality in Saemangeum area with attention to temporal and spatial distributions. A high variability in rainfall was noted during July and August. The temporal analysis of water quality data indicated that DO and TN as well as BOD, COD and SS were within national standards except for increased concentrations during spring and summer, unlike TP values that indicated poor water quality. Standard deviation showed a high variability in SS among the seasons most especially during summer. The high dispersion indicated variability in the chemical composition of pollutants where the temporal and spatial variations caused by polluting sources and/or seasonal changes were most evident for BOD and COD during winter and spring. The box plots and bar charts showed steadily low concentrations of BOD, COD, TN and TP except within Iksan and notable significant variations in SS concentrations among the monitoring stations. Thus, high pollution levels requiring intervention were identified in Mangyeong river basin with particular concern for areas represented by Iksan station. It was noted that Iksan received a considerable amount of rainfall which meant high runoff which could explain the significant pollution levels revealed in the water quality spatial distribution. Major pollution contributing pollutants within Saemangeum area were identified as SS, BOD, COD and TN. Therefore the present results could be used as a guideline for the temporal and spatial distributions analysis of both rainfall and water quality in Saemangeum watershed.

새만금유역 비점오염 중점관리 대상지역 규명

난캬모니카 ( Nankya Monica ),이슬기 ( Seulgi Lee ),최경숙 ( Kyungsook Choi ) 한국농공학회 2013 한국농공학회 학술대회초록집 Vol.2013 No.-

Non point source (NPS) pollution is the most uncontrollable in water pollution and this restricts socio-economic sustainability in development globally. Identification of critical source areas is important in pollution modeling given the fact that contamination caused by non point source (NPS) pollution differs greatly among the different land use types. The purpose of this study is to identify critical source areas contributing high NPS pollutions within Saemangeum watershed by using SWAT model. To realize our goal, the model was set up using digitized DEM, land use and soil maps of scale 1 : 25,000, weather data from Korea Meteorological Administration website as well as water quality parameters from Water Information System. To minimize on uncertainties of the predictions, the model was first calibrated and validated for various parameters. Then it was evaluated using quantitative measures such as NSE and R2 and visual comparisons. Critical Source Areas were identified and analyzed based on loadings per unit area at sub-watershed level. Sub-watersheds were ranked in descending order with the highest load per unit area ranked first and so on. Finally the results from different sub-watershed assessed and ranked to find the critical source areas contributing the highest NPS pollution in the whole watershed area. The results of this research will be beneficial in Saemangeum's current and future drive for allocating resources to successfully address non point source pollution and to meet the required water quality standards.

Statistical analysis of NPS Pollution in Saemangeum Watershed

난캬모니카 ( Nankya Monica ),이슬기 ( Seulgi Lee ),최경숙 ( Kyungsook Choi ) 한국농공학회 2014 한국농공학회 학술대회초록집 Vol.2014 No.-

This study performed a multivariate statistical analysis of NPS pollution data of Saemangeum watershed to understand spatial and temporal patterns and to identify potential pollution sources. Multivariate statistical methods, such as cluster analysis (CA), discriminant analysis (DA) and factor analysis/principal component analysis (FA/PCA), were used to analyze the water quality dataset surveyed on monthly and 8-day basis including 6 parameters namely; DO, BOD, COD, SS, TN and TP from 22 monitoring sites within the study area for period of 2001 to 2013. Correlation between pollution items of the water quality data was carried using spearman’s correlation method. Results revealed strong positive correlation between BOD and COD, and also between BOD and TP indicating presence of biologically active organic matter. CA classified 12 months into 4 seasons and the 22 monitoring sites into two groups based on the two estuaries of Dongjin and Mangyeong. With the use of DA, 3 water quality parameters from the monthly dataset were identified namely DO, TN and TP and similarly for 8-day dataset were DO, BOD and COD were identified for distinguishing seasons, with 51.3% and 50.3% correct assignment respectively for temporal variation analysis. While 5 parameters that is BOD, COD, SS, TN and TP were revealed to correct assignment of 77.1% of monthly data and 4 parameters namely DO, BOD, SS and TN to 71.7% of 8-day data for the spatial variation analysis. FA/ PCA were applied to standardized log-transformed data sets of the 2 spatial groups for both monthly and 8-day datasets. This resulted in 2 latent factors each for both monthly and 8-day data explaining 70.6% and 60.9% of the total variance respectively in the dataset of Dongjin and similarly one latent factor each for both monthly and 8-day data explaining 76.9% and 63% of the total variance respectively of Mangyeong dataset. These results provide a basis for NPS pollution management and the extracted cluster analysis grouping information could be used in reducing the number of monitoring stations in the study area without missing much information.

Mesoporous Graphene-Modified Electrode for Independent and Selective Detection of Dopamine in the Presence of High Concentration of Ascorbic Acid

Rosalynn Nankya,David O. Opar,Hyun Jung 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.2

Mesoporous graphene (MG) synthesized via a facile hydrothermal method using soft-template, triblock copolymer P123 and graphene oxide was utilized for the detection of dopamine (DA) in the presence of ascorbic acid (AA). The structure and morphology of the obtained MG were analyzed by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and nitrogen adsorption?desorption isotherms. The obtained MG was dispersed in DMF solution and then drop-casted on to a platinum plate. It was primarily tested for electrochemical sensing of biomolecules. Cyclic voltammetry and differential pulse voltammetry (DPV) were used to evaluate the electrochemical behaviors of MG on a platinum electrode. DPV facilitated selective and sensitive detection of DA in the presence of a high concentration of AA. MG showed a faster electron transfer rate and increased current density. It exhibited good sensitivity, selectivity, and a linear relationship with concentration, with a 7 ?M limit of detection, suggesting that MG is a promising material for electrochemical sensing applications.

Rainfall and Water Quality Characteristics of Saemangeum Area

Monica, Nankya,Choi, Kyung-Sook 경북대학교 농업생명과학대학 2014 Current Research on Agriculture and Life Sciences Vol.32 No.4

This study investigated characteristics of rainfall and water quality in Saemangeum area with attention to temporal and spatial distributions. A high variability in rainfall was noted during July and August. The temporal analysis of water quality data indicated that DO and TN as well as BOD, COD and SS were within national standards except for increased concentrations during spring and summer, unlike TP values that indicated poor water quality. Standard deviation showed a high variability in SS among the seasons most especially during summer. The high dispersion indicated variability in the chemical composition of pollutants where the temporal and spatial variations caused by polluting sources and/or seasonal changes were most evident for BOD and COD during winter and spring. The box plots and bar charts showed steadily low concentrations of BOD, COD, TN and TP except within Iksan and notable significant variations in SS concentrations among the monitoring stations. Thus, high pollution levels requiring intervention were identified in Mangyeong river basin with particular concern for areas represented by Iksan station. It was noted that Iksan received a considerable amount of rainfall which meant high runoff which could explain the significant pollution levels revealed in the water quality spatial distribution. Major pollution contributing pollutants within Saemangeum area were identified as SS, BOD, COD and TN. Therefore the present results could be used as a guideline for the temporal and spatial distributions analysis of both rainfall and water quality in Saemangeum watershed.

Fine-tuning the pore size of mesoporous graphene in a few nanometer-scale by controlling the interaction between graphite oxide sheets

Lee, Jihye,Nankya, Rosalynn,Kim, Aran,Jung, Hyun Elsevier 2018 ELECTROCHIMICA ACTA Vol.290 No.-

<P><B>Abstract</B></P> <P>Mesoporous graphene (MG) was successfully synthesized by using the soft-template method with graphite oxide (GO) and triblock co-polymer (P123). The obtained MGs exhibit a high surface area as well as tuned pore parameters by preparing GO/P123 composite gel under different reaction conditions. Freeze-drying of the composite gel leads to physical interaction between the GO sheets, which induced the largest pores in MG. While, hydrothermal treatment can generate the chemical linkage between GOs through various reactions of oxygen functional groups on GOs, it facilitates the formation of relatively smaller and more uniform pores. Especially, the presence of a base catalyst under hydrothermal reaction accelerates the chemical reactions, which causes the smallest and most uniform pores. As controlling the interaction between GOs, the pore size of the MGs was easily fine-tuned in a few nanometer-scales never reported. Herein, the electrochemical performance was preliminarily tested as a supercapacitor among the various applications of MG. As a results, the hydrothermal treated sample shows the highest specific capacitance of 151.8 F g<SUP>−1</SUP> at a current density of 0.1 A g<SUP>−1</SUP>. Additionally, it exhibits excellent cycle stability with ∼96% retention of its initial capacitance at a current density of 3.0 A g<SUP>−1</SUP> even after 5000 cycles.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

새만금유역의 초생대 적용성 연구

이슬기 ( Seulgi Lee ),김주영 ( Jooyoung Kim ),난캬모니카 ( Nankya Monica ),장정렬 ( Jeongryeol Jang ),최경숙 ( Kyungsook Choi ) 한국농공학회 2013 한국농공학회 학술대회초록집 Vol.2013 No.-

새만금유역 농업비점오염저감을 위한 밭 비점오염저감기술개발 연구의 세부과제로 수행되고 있는 초생대 밭 비점오염 저감효과 평가 및 제어대책 개발에 대한 1단계 연구가 2010년에 시작하여 2012년에 종료되었다. 1단계 연구에서는 기반구축단계로서 초생대 연구체계 구축 및 요소기술 개발을 포함하고 있으며, 우리나라 밭경지에 초생대로 적용하기에 적합한 초생대 초종의 선정과 선정된 초종에 대한 검증, 생육 특이성과 유지관리 측면에 대한 연구가 진행되었다. 2단계 연구는 기술개발단계로서 2013년부터 2014년까지 진행될 예정이며, 초생대 BMPs기술 개발 및 새만금유역 적용성 평가를 목표로 하고 있다. 본 연구는 2013년에 시작된 2단계 연구를 수행하기 위해 새만금유역에 초생대 시험포를 조성하였다. 전라북도 익산시 금마면 동고도리 1073-9번지 일대에 밭경지 3,750m²을 임대하여 관행재배를 하는 대조구 3개소와 초생대 처리구 3개소를 배치하였다. 시험포는 상하단 두 구역으로 나누어 상단에는 경사 9%, 길이 22m×폭 15m (초생대 길이 2m×폭 5m 포함)규모의 시험구를 대조구 2개소와 초생대 2개소로 배치하여 초생대 요소기술 개발을 지속하였고, 하단에는 경사 5%, 길이 15m×폭 15m (초생대 길이 2m×폭 15m 포함) 규모의 시험구로 대조구 1개소, 초생대 1개소를 배치하여 필지단위의 초생대 연구를 진행하였다. 밭경지에는 새만금유역의 대표 밭작물인 콩을 선정하여 재배하였으며, 밭작물 재배와 초생대 조성을 위해 관개용 호스를 설치하고, 유출수를 원활하게 배제하기 위해 시험구 주변과 말단에 배수로를 설치하였다. 초생대는 1단계 연구에서 최적의 초생대 초종으로 선정된 잔디로 조성하였으며, 각 시험구별 초생대 유출수 모니터링을 위해 플륨과 수위계를 설치하여 유량을 측정하였고, 강우량계와 모바일자동채수기를 설치하여 강우시 수질 시료채취를 원활하도록 하였다. 시험구 토양 특성은 pH 4.5~6.2의 산성토양으로 유기물함량은 약 2%정도였고, 토성은 Silt loam인 1개의 시험구를 제외하고는 모두 Loam이었다. 8월 현재까지의 강우-유출 및 수질시료분석결과 잔디초생대의 유출저감효과은 1.76~9.51%로 나타났으며, 대조구보다 느린 유출발생시기와 낮은 첨두유량을 나타내었다. 수질항목별로 EMC를 산정하여 비점오염저감효과를 분석하였으며,그 결과 SS, T-P, T_N, NO₃^--N,NH₄⁺-N, COD, DOC, PO₄-P 등에서 3.02~61.01% 정도의 저감효과를 보였으나 시료채취시기에 잔디초생대의 피복율이 60%밖에 되지 않은 점을 감안하면 향후 더 좋은 결과가 도출될 수 있을 것으로 기대된다. 시험포 조성 후 연구대상지역에 유출이 발생할 수준의 강우발생이 빈번하지 않아 현재까지 제한적인 연구가 수행되었으며, 향후 지속적인 모니터링을 통해 보다 심도깊은 초생대의 유출 및 비점오염저감효과를 파악하고자 한다.