암반 대수층 내 질산성 질소 오염 거동 특성에 따른 탄소원 기반 생물학적 자연저감촉진 평가

이다원 고려대학교 그린스쿨대학원 2021 국내석사

본 연구에서는, 가축 매몰지 인근에 위치한 연구지역 (양평) 의 암반 대수층내 탄소원 주입에 의한 질산성 질소 생물학적 자연저감 촉진 양상을 모니터링 및 평가하였다. 세 가지 탄소원 (succinate, acetate, fumarate) 을 현장 지하수에 주입하여 탈질 능력을 평가한 결과, acetate 가 지하수내 질산성 질소 제거효과와 미생물 활성도를 향상시키며 가장 적합한 탄소원으로 선정되었다. 또한, C/N ratio = 2.1 : 1 의 조건으로 acetate 가 주입되었을 때 가장 높은 비율의 탈질 미생물 (CN 2.1 (2.1%) > CN 4.2 (1.9%) > CN 7.0 (0.9%) > control (0.7%)) 이 존재함을 확인하였다. 암반 대수층의 지중환경 특성을 반영하여, 연구지역 지하수에 최적 탄소원 주입 조건을 바탕으로 탄소원을 주입하여 생물학적 탈질 반응을 촉진시-켰다. 그 결과, 지하수내 질산성 질소 저감 속도는 0.377 g-N/day 로 나타났으며, 탄소원의 영향을 받지 않은 지하수의 경우 같은 반응시간 동안 0.028 g-N/day 의 현저히 낮은 저감 속도를 보였다. 특히, 대표적인 탈질 미생물인Dechloromonas denitrificans sp. 의 비율 (주입 전; 0.0089%, 주입 후; 1.3067%) 이 급증하였고, 혐기성 종속 탈질 반응에 관여하는 nosZ gene 이 4.82 Log(gene copies L-1) 에서 9.71 Log(gene copies L-1)로 증가하였다. 이러한 결과로부터, 탄소원 주입에 의한 암반 대수층내 탈질 촉진 효과가 유전학적으로 확인되었다. In this study, the natural attenuation-potential and biogeochemical anaylsis in nitrate contaminated bed-rock aquifers located near the burial site of livestock by injection of C-sources was evaluated. The ability of denitrification was assessed by injecting different C-sources (succinate, acetate, fumrate) into the field groundwater, and acetate was derived as field-optimum sources as electron donors for microbial metabolic process, improving the effect of nitrate removal and microbial activity in the groundwater. In addition, when acetate was injected by C/N ratio = 2.1 : 1, the ratio of denitrifying bacteria showed the highest ratio (CN 2.1 (2.1%) > CN 4.2 (1.9%) > CN 7.0 (0.9%) > control (0.7%)). Reflecting the geochemical characteristics of the bed-rock aquifers environment, acetate was injected into groundwater of research site to activate biological heterotrophic denitrification. As a result, the nitrate reduction rate was 0.377 g-N/day (YP-3), and for groundwater unaffected by acetate, it showed a significantly lower reduction rate of 0.028 g-N/day (YP-4) over the same reaction time. In particular, the ratio of the Dechloromonas denitrificans sp. which is a representative denitrification bacteria involved in anaerobic reduction of nitrate, increased (before injection; 0.0089%, after injection; 1.3067%). And the nosZ gene, which related denitrification pathway (N2O→N2), increased from 4.82 Log (gene copies L-1) to 9.71 Log (gene copies L-1). From these results, the effect of activating denitrification in the bed-rock aquifers by injection of C-source was genetically identified.

Hydrogeochemical characterization of urban groundwater in Seoul, South Korea, using self-organizing map (SOM) and fuzzy c-means (FCM) clustering

이경진 Graduate School, Korea University 2014 국내석사

In this work, combined statistical approaches were conducted for quantitative evaluation of urban groundwater quality of Seoul metro-politan city. The main purposes of this study are: 1) to classify and characterize physico-chemical properties of groundwater in Seoul, and 2) to understand geochemical evolutions of groundwater which are strongly affected by spatial distribution of environmental/anthropogenic factors. Coupled multivariate statistical methods had been applied to the groundwater chemistry data (n=343). A total of 91 prototype vectors for 13 water quality variables were derived by the self-organizing map (SOM) technique. However, the SOM result was insufficient to grasp the overall pattern of water quality. Thus, we used the fuzzy c-means (FCM) clustering algorithm to the SOM result for more effective and quantitative data interpretation. Accordingly, the prototype vectors were classified into four main hydrogeochemical groups based on their fuzzy membership values. The spatial pattern of groundwater chemistry was then examined using the ordinary cokriging on the fuzzy membership values following the additive log-ratio transformation (ALR). The result showed a distinct spatial relationship between groundwater quality and environmental/ anthropogenic factors. The physico-chemical and spatial characteristics of each groundwater group are summarized as follows: 1) Group 1 represents groundwater with low EC (median=181 μS cm-1) and high DO values (median=6.79 mg L-1), and mainly locates in the northern mountainous area of Seoul 2) Group 2 water has intermediate EC values (median=362 μS cm-1) and high pH (median=7.80), and dominantly occurs at the southern mountainous part 3) Group 3 represents water with high Eh levels (median=457.8 mV) and high nitrate concentration (median=42.7 mg L-1), and distributes ubiquitously in Seoul 4) Group 4 groundwater has the highest EC values (median=589 μS cm-1) among four groundwater groups and dominantly occurs in the center of the city.

Quantification of the effects of dumped manure waste from livestock farming to the grounfwater quality using stable N and O isotopes of NO3-in conjunction with hydrochemistry data

윤성재 Green School Graduate School of Energy and Environ 2016 국내석사

Land use control of groundwater quality in the Pyosun Watershed, Jeju volcanic island, Korea

고영화 고려대학교 대학원 2012 국내석사

As groundwater from basaltic to trachytic aquifers is a unique source of water supply in the volcanic Jeju Island, Korea, a better understanding of the current status of groundwater is important for a sustainable future water supply. For this study of the Pyosun Watershed located at the southeastern part of the island, we collected 90 groundwater samples from 45 existing wells and 41 soil water samples using porous cups installed at various depths at two sites. Hydrochemically, well groundwater was dominantly of the Na(-Mg-Ca)-HCO3(-Cl) type, while soil water varied between Na(-Mg-Ca)-Cl-HCO3(-SO4) type at an upgradient forested area to a Na(-Mg-Ca)-Cl type at a downgradient agricultural (orchard) area. Most ions in groundwater, especially NO3, Cl, SO4, Na, Ca and Mg, increased in concentrations in aquifers at low altitudes (about <150 m a.s.l.) where land use is dominated by orchards and rural developments. Nitrate concentrations of groundwater ranged from 0.4 to 23.3 mg/L (median 4.7 mg/L). The result of the Factor Analysis (FA) of hydrochemical data indicated that two major processes (i.e., anthropogenic contamination and water-rock interaction) control the groundwater chemistry. Water-rock interactions were dominated by silicate weathering (as indicated by the increases of HCO3 and silica) with minor ion exchange and sorption. The inverse modeling using PHREEQC show that groundwater evolution through water-rock interaction can be well explained by the dissolution of olivine, plagioclase and K-feldspar.

Classification of hydrochemical facies using cluster analysis of groundwater hydrochemistry data : an example from Anseong area, Korea

최수빈 Graduate School, Korea University 2016 국내석사

Graphical methods (e.g., Piper diagram) and statistical cluster analysis (e.g., hierarchical clustering) have been used to cluster water samples as an initial step to interpret hydrochemical processes (natural versus anthropogenic) controlling groundwater quality. However, these conventional approaches can be unsatisfactory for reasonable interpretation because 1) groundwater quality can be too complex to successfully analyze using conventional graphical methods, 2) hydrochemical properties of the natural groundwater system can vary continuously, and 3) statistically, the geometrical space of compositional data makes up the simplex and therefore the distance between two compositional observations should be measured by the Aitchison distance, whereas most of statistical clustering methods are based on Euclidean space. This study aims 1) to classify hydrochemical data (compositional data), which was difficult to classify by using hard clustering, through Fuzzy C-menas clustering after performing ilr transformation of hydrochemical data for using strictly statistical methods (fuzzy c-means clustering, PCA, modified piper diagram) in Anseong area. Additionally, 2) we suggest a new quantitative criteria named ANSI (Anthropogenic and Natural Source Identification) to distinguish whether groundwater quality is affected by natural or anthropogenic sources. For this study, hydrochemical data of 77 groundwater samples were collected in an agricultural area of Anseong, South Korea. The ilr (isometric log-ratio)-transformed data of the concentrations of ion (Na+K, Ca, Mg, HCO3, SO4, NO3+Cl, Si) were interpreted using the soft clustering method (i.e., Fuzzy C-means clustering). Then, the fuzziness of the samples belonging to specific groups was plotted on modified Piper diagram for the visualization of quantitative clustering results. In addition, the principal component analysis (PCA) was conducted to understand the factors determining hydrochemical facies. The results yielded three well-defined water types: 1) Ca-HCO3, 2) Ca-SO4, and 3) Ca-Cl-NO3 types. Each group is interpreted to represent distinct groundwater masses: 1) Ca-HCO3 type represents the groundwater quality that affected by natural processes and rarely affected by anthropogenic pollution. 2) Ca-SO4 type describes the groundwater quality that affected by human activities and shows especially highest SO4 concentration, and 3) Ca-Cl-NO3 type represents the groundwater quality that affected by anthropogenic pollutants such as agriculture practices and industrial effluents and indicates highest NO3 concentration. In order to understand the water quality, we plotted groundwater samples at modified piper diagram. We suggest a new quantitative criteria named ANSI (Anthropogenic and Natural Source Identification) to distinguish whether groundwater quality is affected by natural or anthropogenic sources. ANSI index is the ratio of HCO3 versus the geometric mean of SO4 and Cl+NO3. The average value of ANSI indices of overlapping range between natural groundwater (Cluster 1) and polluted groundwater (Cluster 2 and 3) is 1.55. Groundwater with ANSI index≥1.55 is regarded as non-polluted natural groundwater, while groundwater with ANSI index≤1.55 is regarded as polluted groundwater affected by anthropogenic activities. The spatial distribution of ANSI index is well explained by the land use patterns of the study area. Therefore, ANSI index can be proposed as a useful tool to identify the origin of natural and anthropogenic sources of groundwater.

Nitrate contamination of groundwater in agro-livestock farming districts, South Korea : geostatistical interpretation of large hydrochemical and environmental isotopic datasets

김호림 Green School Graduate School of Energy and Environ 2019 국내박사

Evaluation of groundwater contamination of by livestock carcass leachate is a challenging but very important task for managing groundwater quality in agro-livestock farming area. For this purpose, we investigated the groundwater chemistry in seven areas with livestock burial in South Korea. Four types of samples (total N = 364) were collected: (a) LC (n = 29): leachate samples collected from burial pits, (b) MW (n = 40): groundwater samples from monitoring wells near (< 5 m) the burial pit, (c) HW (n = 230): groundwater samples from agricultural and rural household wells located between 50 and 800 m away from the burial pit, (d) BG (n = 46): groundwater samples from background wells. Box plots and the results of Kruskal-Wallis One-way ANOVA on Ranks showed that hydrochemical characteristics are significantly different among groups (p < 0.05): impacts from leachate are obvious near some burial pits, which is discernible by very high concentrations of major ions and heavy metals under pronounced reducing conditions. Linear discriminant analysis (LDA) was employed to qualitatively evaluate the impact of leachate from carcass burial pits, by using the samples LC and BG as training dataset. The results showed that pH, DO (dissolved oxygen), EC (electrical conductivity), Mg, NH4+, total Fe and Mn are the most significant variables in the discriminant function to discriminate the impact of leachate on groundwater quality. By applying discriminant functions to the samples MW and HW, 62.5% of MW and 20.6% of HW were interpreted to be affected by leachate. This study also suggests that the transport of leachate from livestock burial sites to surrounding groundwater environment can be over significant distances; therefore, careful management of the construction of carcass burial pits is needed to prevent leaking of leachate. In last several decades, the nitrogen cycle has been significantly perturbed, largely due to intensification of agricultural activities throughout the world. In this study, we examined the impact of agricultural N inputs on the quality and chemistry of shallow groundwater, based on a large hydrochemical dataset (n = 4,000) collected from 100 agro-livestock farming districts in South Korea. The South Korean groundwater, studied mostly in silicate aquifers, shows very high nitrate concentrations (median NO3- = 22.2 mg/L) and acidification (median pH = 5.6). The groundwater nitrate levels tend to increase with the estimated N loadings, and the groundwater pH generally decreases with increasing nitrate levels. The relationship between the concentrations of Ca2+ + Mg2+ and HCO3- has a moderate adjusted R2 value (0.4), but the molar (Ca2+ + Mg2+) / HCO3- ratios (r) tend to increase with nitrate concentrations. This implies that the chemical composition of the groundwater is controlled by multiple hydrogeochemical processes, which include weathering of silicates and carbonates induced by carbonic acid (r = 0.5), nitrification (r ≥ 1) and denitrification (mostly, r < 0.5 in this study). In particular, undrinkable (> 44.3 mg/L) groundwater (n = 988) shows an average molar ratio of 1.04, indicating that such highly contaminated groundwater experiences the enhanced geochemical weathering of aquifer materials by an anthropogenic process (i.e., nitrification). The results of principal component (PC) analysis also support our explanation: the first PC shows significant negative correlations with major components including NO3- while there is a weak positive correlation with pH, indicating anthropogenically enhanced weathering that includes the buffering process by agricultural liming materials (e.g., limestone (CaCO3)), while the second PC shows negative correlations with Eh, DO and NO3- but positive correlations with pH and HCO3-, suggesting the denitrification process. A few groundwater samples (about 4 %) experienced heterotrophic denitrification, and they have molar ratios (r) of less than 0.5. The results of this study indicate that 1) geochemical weathering of aquifer materials in shallow groundwater systems is enhanced by nitrate contamination caused by high N loadings in agro-livestock farming districts, causing increased salinity, and 2) the prevailing hydrochemical process can be interpreted by the molar (Ca2+ + Mg2+) / HCO3- ratios of groundwater. Excessive nitrogen (N) application in agro-livestock areas has led to serious groundwater contamination; efficient controls of N loads are crucial to managing nitrate contamination in groundwater. We examined the impact of anthropogenic N loading on groundwater nitrate levels to suggest optimal N limits, using a large dataset (n = 4,000) collected in 2012-2014 from 100 agro-livestock farming zones. Quantile regression was performed to assess the relationship between nitrate contamination and anthropogenic N input across the full range of conditional distribution of nitrate concentrations because of heteroscedasticity. As a result, positive gradients (βτ) were found between nitrate concentrations and N loads at all quantiles. βτ increased as the quantile was higher and was as large as 36.48 ± 10.95 mg NO3-/L per total N input (in a log scale) at the 90% quantile. A quantile map indicated that the high gradient (i.e., the large sensitivity to N loading) was related with agricultural land use, low elevation, and low slope angle. In fact, nitrate concentrations increased as the percentage of agricultural land increased and the percentage of forest, elevation and slope angle decreased, which suggests that land use, elevation, and slope should be considered when attempting to evaluate N application limits. This study suggested N limits below 170 kg ha-1 year-1 based on the drinking water standard (44.3 mg/L as NO3-) at the quantiles higher than 70%, which was mostly located in agricultural flat lowland areas. Our method can be applied to other countries to establish efficient management practices of groundwater nitrate contamination, with considering local environmental factors. The spatio-temporal variations of nitrate concentrations in groundwater of Jeju Island were evaluated by an analysis of time series groundwater quality data (N = 21,568) that were collected from regional groundwater monitoring (number of wells = 4835) for up to 20 years between 1993 and 2015. The median concentration of NO3-N is 11.1 mg/L, which is slightly higher than those reported from regional surveys in other countries. Nitrate concentrations of groundwater in wells tend to significantly vary according to different water usage (of the well), administrative districts, and topographic elevations: nitrate level is higher in low-lying agricultural and residential areas than those in high mountainous areas. The Mann–Kendall trend test and Sen’s slope analysis show that nitrate concentration in mid-mountainous areas tends to increase, possibly due to the expansion of agricultural areas toward highland. On the other hand, nitrate concentrations in the specially designated Groundwater Quality Protection Zones show the temporally decreasing trend, which implies the efficiency of groundwater management actions in Jeju. Proper measures for sustainable groundwater quality management are suggested in this study.

Geochemical assessment of vanadium distribution in groundwater of Jeju volcanic island

정지혜 Graduate School, Korea University 2017 국내석사

Vanadium is typically more enriched in mafic rocks such as basalt than in felsic rocks and its behavior of leaching and mobility is sensitive to oxidation-reduction condition. Recently there has been a public interest on the use of vanadium-rich groundwater in Jeju volcanic island of South Korea and other localities in the world. Thus, better knowledge on the occurrence and geologic/geochemical controls of vanadium enrichment in groundwater is needed. In this study, spatiotemporal patterns of the distribution of vanadium in groundwater in Jeju are evaluated using hydrochemical data of groundwater samples that were collected by the Institute of Enviroment Research of Jeju Special Self-Governing Province and Jeju Province Development Corporation between 2009 and 2014. Data of a total of 757 groundwater samples (134 in 2009, 296 in 2010, 327 in 2014) are used in this study and include major ions (Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, NO3-, SO42-, F-), vanadium and other minor elements (Cr, Mn, Fe, As, Al, Cu, Se, Si, Sr, Li, Zn). The concentrations of vanadium in Jeju groundwater from trachybasaltic to basaltic aquifers are wide from “not detected (< 2.5 μg/L)” to 64.8 μg/L, with the median value of 9.1 μg/L. Vanadium was found to be occurring from weathering of rocks that were formed from volcanic activities. The behavior of vanadium in the study area appeared in the form of VO2(OH)2 , which is one of ionic species of V(V), and it was deduced that this form had comparably high mobility within the groundwater. The pH value had a positive correlation with vanadium concentration while with nitrate, it had a negative correlation. Moreover, the pH and vanadium predominated water with Na-HCO3, while nitrate predominated water with Ca-Cl- SO4. This phenomenon seemed to have been influenced by the nitrification process. Decreasing pH caused vanadium to adsorb to the oxide surface. This reduced the mobility and solubility of vanadium in groundwater, and therefore, the concentration of vanadium decreased. The depth of a well was also one of the factors that reduced the concentration of vanadium. This was because in the lowland, the influent water with anthropogenic pollutants may possibly flow into the groundwater. The spatiotemporal analysis of the study area did not show temporal differences, however, the concentration of vanadium showed significant statistical differences in the spatial elements such as land use and altitude.

(The) use of stable O-H isotope data to evaluate groundwater recharge in Jeju Island, Korea

유연경 Graduate School, Korea Univeristy 2017 국내석사

Groundwater aquifers in oceanic islands, such as Jeju Island of South Korea, are the primary source of water supply and are largely replenished by rainwater infiltration. For sustainable exploitation and management of groundwater, it is crucial to understand recharge characteristics. In this study, groundwater recharge in the Pyoseon watershed of Jeju volcanic island was elucidated by comparing 4-year O and H isotope data of rainwater from seven altitudes with those of groundwater from three deep wells for the production of bottled drinking water. A total of 173 rainwater samples show distinct seasonal and altitudinal changes. In wet season (May-October) the isotopic compositions plot along the equation δD = 8.12δ18O + 10.40, while the precipitation during dry season (November-April) show the regression equation δD = 6.63δ18O + 12.67. Rainwater also shows the systematic decrease of isotopic composition with increasing elevation (-1.03‰/100m for δ18O and -0.11‰/100m for δD). In contrast, groundwater shows unique O and H isotopic compositions with no distinct seasonal change. Isotopic characteristics of groundwater indicate the high flow rates of groundwater without significant water-rock interaction, possibly through highly permeable aquifers. The calculated d-values of groundwater indicated that the groundwater recharge occurs mainly from summer precipitation at high altitudes (>1,210 m a.s.l.). This study shows a good example of the usefulness of the long-term stable isotope study to understand groundwater recharge in volcanic aquifers.

제 7차 중등 교육과정의 과학 교과목간 교과 과정의 연계성에 대한 고찰 : 지구과학 교과과정을 중심으로

허진영 고려대학교 교육대학원 2005 국내석사

철도오염토양 내 윤활유 처리에 있어 동전기-펜톤 산화 연계 공정의 적용을 위한 실험 연구

강해숙 高麗大學校 大學院 2011 국내석사

철도토양오염은 선로분기기 등의 시설물 유지보수 시 사용되는 그리스 및 윤활유 등과 같은 중유의 낙유 및 누유에 의해서 유발된다. 특히 디젤유에 비해 탄소수가 많은 고분자성 유기화합물질인 윤활유의 특성으로 인해 일반적인 정화기술로는 제거가 어려워 오염토양정화에 더 많은 시간과 비용이 소요된다. 본 연구에서 고분자성 유기화합물질인 윤활유를 처리하기 위해 사용된 “동전기 기술”은 대표적인 원위치 토양정화기술 중 하나로 유기오염물질과 중금속이 함께 오염된 복합오염 토양에도 매우 유용한 정화기술이다. 보통 제거가 어려운 고분자 유기화합물질의 처리에 있어서 동전기 기술만을 적용하는 것 보다는 토양 세정, 펜톤 산화, 생물학적 복원 등과 같은 타 정화기술을 함께 사용하는 것이 보다 효과적임으로 처리속도 및 효율을 증대시키고자 펜톤산화 공정을 동전기 기술에 연계하였다. 먼저 A 지역에서 확보한 윤활유 오염 철도토양에의 동전기-펜톤산화 기술적용 가능성을 살펴보기 위해 토양기본특성 조사를 한 결과, 일반 토양에 비해 토양 내 철 함량이 23.56%으로 높아 동전기-펜톤산화 기술적용이 가능함을 알 수 있었다. 동전기-펜톤산화 기술은 동전기에 의해 토양 속을 이동하는 과산화수소가 토양 내 2가 철과 반응하여 생성된 hydroxyl radical이 유기오염물질을 산화시켜 오염을 정화하는 기술이다. 촉매제로 사용된 과산화수소는 3.3%, 5%, 10%(v/v) 농도를 사용하였고, 전해질은 0.05M, 0.1M, 0.2M의 NaCl, MgSO4, HNO3을 각각 사용하였다. 모든 실험은 1V/cm 조건에서 3주간 진행하였다. 그 결과, 0.1M NaCl 전해질과 5%(v/v) 농도의 과산화수소를 사용했을 때 가장 높은 TPH 제거효율이 나타났다. 결론적으로 윤활유로 오염된 철도토양을 정화하기 위해 실험실 규모의 동전기-펜톤 산화 공정에서 주요 운전인자들의 영향을 살펴보았으며, 그 결과 오염토양 내 윤활유(TPH)를 원위치 조건에서 효과적으로 제거 가능함을 확인하였다.