Stable Nitrogen Isotopes in a Forested Watershed in Taiwan

Jeffrey S. Owen 강원대학교 산림과학연구소 2013 Journal of Forest Science Vol.29 No.2

Differences in rates and patterns of nitrogen cycling have been correlated with nitrogen stable isotope measurements in forest ecosystems of tropical and temperate regions, but limited similar work has been conducted in sub-tropical forests. This study investigated patterns in stable N isotopic composition in a subtropical forest in Taiwan by sampling three soil profiles and overstory and understory foliage. Soil δ15N in the forest floor ranged from - 1.8 to 1.8‰. Mineral soils had higher δ15N (4.1 to 6.0‰). Foliage δ15N in overstory trees ranged from -6.6 to -2.0‰, and understory foliage δ15N ranged from -5.0 to -1.2‰. There was a weak correlation between foliar % N and δ15N (r2=0.214). Compared to results from similar surveys in tropical and temperate forests, foliar δ15N values were generally lower. These results help highlight the need for improved knowledge regarding the relationships between patterns in N stable isotopes and processes affecting rates of N cycling, especially as related to wider scale patterns in forest ecosystems within the east-Asia region.

Enhanced Biodegradation of Total Petroleum Hydrocarbons (TPHs) in Contaminated Soil using Biocatalyst

Jeffrey S. Owen,표선연,강구영 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.5

Biocatalytic degradation of total petroleum hydrocarbons (TPHs) in contaminated soil by hemoglobin and hydrogen peroxide is an effective soil remediation method. This study used a laboratory soil reactor experiment to evaluate the effectiveness of a nonspecific biocatalytic reaction with hemoglobin and H2O2 for treating TPH-contaminated soil. We also quantified changes in the soil microbial community using real-time PCR analysis during the experimental treatment. The results show that the measured rate constant for the reaction with added hemoglobin was 0.051/day, about 3.5 times higher than the constant for the reaction with only H2O2 (0.014/day). After four weeks of treatment, 76% of the initial soil TPH concentration was removed with hemoglobin and hydrogen peroxide treatment. The removal of initial soil TPH concentration was 26% when only hydrogen peroxide was used. The soil microbial community, based on 16S rRNA gene copy number, was higher (7.1 × 106 copy number/g of bacteria, and 7.4 × 105 copy number/g of Archaea, respectively) in the hemoglobin catalyzed treatment. Our results show that TPH treatment in contaminated soil using hemoglobin catalyzed oxidation led to the enhanced removal effectiveness and was non-toxic to the native soil microbial community in the initial soil.

Stable Nitrogen Isotopes in a Forested Watershed in Taiwan

Owen, Jeffrey S. Institute of Forest Science 2013 Journal of Forest Science Vol.29 No.2

Differences in rates and patterns of nitrogen cycling have been correlated with nitrogen stable isotope measurements in forest ecosystems of tropical and temperate regions, but limited similar work has been conducted in sub-tropical forests. This study investigated patterns in stable N isotopic composition in a subtropical forest in Taiwan by sampling three soil profiles and overstory and understory foliage. Soil ${\delta}^{15}N$ in the forest floor ranged from -1.8 to -1.8‰. Mineral soils had higher ${\delta}^{15}N$ (4.1 to 6.0‰). Foliage ${\delta}^{15}N$ in overstory trees ranged from -6.6 to -2.0‰, and understory foliage ${\delta}^{15}N$ ranged from -5.0 to -1.2‰. There was a weak correlation between foliar % N and ${\delta}^{15}N$ ($r^2=0.214$). Compared to results from similar surveys in tropical and temperate forests, foliar ${\delta}^{15}N$ values were generally lower. These results help highlight the need for improved knowledge regarding the relationships between patterns in N stable isotopes and processes affecting rates of N cycling, especially as related to wider scale patterns in forest ecosystems within the east-Asia region.

Enhanced Biodegradation of Total Petroleum Hydrocarbons (TPHs) in Contaminated Soil using Biocatalyst

Owen, Jeffrey S.,Pyo, Sunyeon,Kang, Guyoung Korean Society of Soil and Groundwater Environment 2015 지하수토양환경 Vol.20 No.5

Biocatalytic degradation of total petroleum hydrocarbons (TPHs) in contaminated soil by hemoglobin and hydrogen peroxide is an effective soil remediation method. This study used a laboratory soil reactor experiment to evaluate the effectiveness of a nonspecific biocatalytic reaction with hemoglobin and H₂O₂ for treating TPH-contaminated soil. We also quantified changes in the soil microbial community using real-time PCR analysis during the experimental treatment. The results show that the measured rate constant for the reaction with added hemoglobin was 0.051/day, about 3.5 times higher than the constant for the reaction with only H₂O₂ (0.014/day). After four weeks of treatment, 76% of the initial soil TPH concentration was removed with hemoglobin and hydrogen peroxide treatment. The removal of initial soil TPH concentration was 26% when only hydrogen peroxide was used. The soil microbial community, based on 16S rRNA gene copy number, was higher (7.1 × 10⁶ copy number/g of bacteria, and 7.4 × 10⁵ copy number/g of Archaea, respectively) in the hemoglobin catalyzed treatment. Our results show that TPH treatment in contaminated soil using hemoglobin catalyzed oxidation led to the enhanced removal effectiveness and was non-toxic to the native soil microbial community in the initial soil.

Habitat-specific variation in stable C and N isotope ratios of pond smelt (Hypomesus nipponensis)

이재용,최재석,Jeffrey S. Owen,이광열,허우명,김범철 한국통합생물학회 2013 Animal cells and systems Vol.17 No.3

The aim of this study was to investigate differences in d13C and d15N of pond smelt (Hypomesus nipponensis)collected from three brackish lagoons, which have different characteristics, the principal one being the presence or absence of a weir located near the mouth of the outlet channel. The presence or absence of a weir is reflected in a difference in salinity among the study lakes.We found a general pattern of lower pond smelt d13C values in Lake Mae with lower salinity and higher pond smelt d13C values in Lake Hwajinpo and Lake Youngrang (lagoons with higher salinity). Pond smelt d13C values showed little variation among the three lagoons related to pond smelt length, but likely reflected the availability of freshwater prey in Lake Mae. Among the lagoons, we found that pond smelt d15N values were lower in Lake Hwajinpo compared with pond smelt d15N values in Lake Youngrang and Lake Mae. This pattern likely shows a difference in anthropogenic nitrogen (N) loading among the lagoons. The results of this study emphasize the utility of stable isotope measurements to better understand how structural characteristics of aquatic ecosystems (presence or absence of a weir) and anthropogenic disturbances can affect stable isotope patterns in aquatic food webs. This stable isotope approach may be a general technique for evaluating fish habitat and restoration or management of coastal lagoon ecosystems.

Patterns in solute chemistry of six inlet streams to Lake Hövsgöl, Mongolia

Tamir Puntsag,Jeffrey S. Owen,Myron J. Mitchell,Clyde E. Goulden,Patrick J. McHale 한국생태학회 2010 Journal of Ecology and Environment Vol.33 No.4

A number of characteristics of the Lake Hövsgöl watershed, such as the lake’s location at the edge of the Central Asian continuous permafrost zone, provide a unique opportunity to evaluate possible anthropogenic impacts in this remote area in northern Mongolia. In this study, we compared stream solute concentrations in six sub-watersheds in the Lake Hövsgöl watershed. Water samples were collected during the summer months between 2003 and 2005. Concentrations of Cl⁻ ranged from 9.8 to 51.3 μmol/L; average nitrate concentrations were very low and ranged from undetectable to 1.1 μmol/L and average SO₄²⁻ concentration at sampling stations with minimal animal grazing ranged from 66 to 294μmol/L. Average dissolved organic carbon (DOC) concentrations ranged from 642 to 1,180 μmol C/L. We did not find statistically significant differences in DOC concentrations among the six streams, although DOC concentrations tended to be higher in the two northernmost streams, possibly related to differences in the active layer above the permafrost. Dissolved organic nitrogen (DON) concentrations were correlated with DOC concentration, and followed the same spatial pattern as those for DOC. In streams in this remote watershed, total dissolved nitrogen was made up of mostly organic N, as has been found for other regions distant from anthropogenic N sources. Overall, these results suggest that future research on the dynamics of DOC and DON in this watershed will be especially insightful in helping to understand how changes in climate and land use patterns will affect transformations, retention, and export of dissolved organic matter within these sub-watersheds in the Lake Hövsgöl region.

Patterns in solute chemistry of six inlet streams to Lake Hövsgöl, Mongolia

Puntsag, Tamir,Owen, Jeffrey S.,Mitchell, Myron J.,Goulden, Clyde E.,McHale, Patrick J. The Ecological Society of Korea 2010 Journal of Ecology and Environment Vol.33 No.4

A number of characteristics of the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed, such as the lake's location at the edge of the Central Asian continuous permafrost zone, provide a unique opportunity to evaluate possible anthropogenic impacts in this remote area in northern Mongolia. In this study, we compared stream solute concentrations in six sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed. Water samples were collected during the summer months between 2003 and 2005. Concentrations of $Cl^-$ ranged from 9.8 to $51.3\;{\mu}mol/L$; average nitrate concentrations were very low and ranged from undetectable to $1.1\;{\mu}mol/L$ and average ${SO_4}^{2-}$ concentration at sampling stations with minimal animal grazing ranged from 66 to $294\;{\mu}mol/L$. Average dissolved organic carbon (DOC) concentrations ranged from 642 to $1,180\;{\mu}mol$ C/L. We did not find statistically significant differences in DOC concentrations among the six streams, although DOC concentrations tended to be higher in the two northernmost streams, possibly related to differences in the active layer above the permafrost. Dissolved organic nitrogen (DON) concentrations were correlated with DOC concentration, and followed the same spatial pattern as those for DOC. In streams in this remote watershed, total dissolved nitrogen was made up of mostly organic N, as has been found for other regions distant from anthropogenic N sources. Overall, these results suggest that future research on the dynamics of DOC and DON in this watershed will be especially insightful in helping to understand how changes in climate and land use patterns will affect transformations, retention, and export of dissolved organic matter within these sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l region.

Microbial Interaction is Among the Key Factors for Isolation of Previous Uncultured Microbes

Yan Chang,Owen Jeffrey S.,Seo Eun-Young,Jung Dawoon,He Shan 한국미생물학회 2023 The journal of microbiology Vol.61 No.7

Pure cultivation of microbes is still limited by the challenges of microbial uncultivability, with most microbial strains unable to be cultivated under standard laboratory conditions. The experience accumulated from advanced techniques such as in situ cultivation has identified that microbial interactions exist in natural habitats but are absent in laboratory cultures. These microbial interactions are likely one of the key factors in isolating previously uncultured microbes. The need for better knowledge of the mechanisms operating in microbial interactions has led to various experiments that have utilized microbial interactions in different approaches to microbial cultivation. These new attempts to understand microbial interactions not only present a new perspective on microbial uncultivability but also provide an opportunity to access uncultured phylogenetically novel microbes with their potential biotechnology applications. In this review, we focus on studies of the mechanisms of microbial interaction where the growth of other microbes is affected. Additionally, we review some successful applications of microbial interactions in cultivation methods, an approach that can play an important role in the bioprospecting of untapped microbial resources.

Stable carbon isotope signatures of zooplankton in some reservoirs in Korea

이재용,김범철,이윤경,장창원,Jeffrey S. Owen,김재구,음재성,성민정 한국생태학회 2013 Journal of Ecology and Environment Vol.36 No.3

Dissolved organic carbon (DOC) concentrations and zooplankton and particulate organic matter (POM) δ13C values were measured in five reservoirs in Korea. Zooplankton δ13C and POM δ13C showed large range from -33‰ to -22‰ and a significant difference among the reservoirs. One eutrophic reservoir, Lake Masan, showed unique characteristics with the highest zooplankton density, the highest δ13C, and the highest DOC. Zooplankton δ13C was similar to POM δ13C, implying that zooplankton occupies substantial portion of POM or that zooplankton isotopic composition is related to selective grazing and assimilation of food sources from bulk POM. Except Lake Masan zooplankton δ13C values were negatively correlated to DOC concentration in four reservoirs with mostly forest land use. This pattern can be probably attributed to intensive agricultural land use in the watershed of Lake Masan compared to the mostly forest land use in the other watersheds. Understanding the relationship between zooplankton δ13C values and the origin of organic matter associated with watershed characteristics will be valuable to better understand trophic relationships in reservoirs in the summer monsoon region.

Optimizing Concentrations of Hemoglobin and Hydrogen Peroxide for Remediation of Benzo(a)pyrene (b[a]p) Contaminated Soils

Hyein Keum,Kapsong Park,Jeffrey S Owen,Guyoung Kang 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6