• Economic and Environmental Geology
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• v.50 no.6
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• pp.537-544
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• 2017

Stable carbon isotope ratio of carbon dioxide (${\delta}^{13}C_{CO2}$) is used as an important indicator in the researches for global climate change and carbon capture and sequestration technology. The ${\delta}^{13}C$ value has been usually analyzed with Isotope Ratio Mass Spectrometer (IRMS). Recently, the use of Laser Absorption Spectrometry (LAS) is increasing because of the cost efficiency and field applicability. The purpose of this study was to suggest practical procedures to prepare laboratory reference gases for ${\delta}^{13}C_{CO2}$ analysis using LAS. $CO_2$ gas was adjusted to have the concentrations within the analytical range. Then, the concentration of $CO_2$ was assessed in a lab approved by the Korea Laboratory Accreditation Scheme and the ${\delta}^{13}C_{CO2}$ value was measured by IRMS. When the instrument ran over 12 hours, the ${\delta}^{13}C$ values were drifted up to ${\pm}10$‰ if the concentration of $CO_2$ was shifted up to 1.0% of relative standard deviation. Therefore, periodical investigation of analytical suitability and correction should be conducted. Because ${\delta}^{13}C_{CO2}$ showed the dependency on $CO_2$ concentration, we suggested the equation for calibrating the concentration effect. After calibration, ${\delta}^{13}C_{CO2}$ was well matched with the result of IRMS within ${\pm}0.52$‰.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.591-597
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• 2015

We determined the total C and N stocks in trees and soils after 1 year of fertilization in an experimental orchard with 16-year-old 'Niitaka' pear (Pyrus pyrifolia Nakai cv. Niitaka) trees planted at $5.0m{\times}3.0m$ spacing on a Tatura trellis system. Pear trees were fertilized at the rate of 200 kg N, 130 kg P and $180kg\;K\;ha^{-1}$. At the sampling time (August 2013), trees were uprooted, separated into six fractions [trunk, main branches, lateral branches (including shoots), leaves, fruit, and roots] and analyzed for their total C and N concentrations and dry masses. Soil samples were collected from 0 to 0.6 m in 0.1 m intervals at 0.5 m from the trunk, air-dried, passed through a 2-mm sieve, and analyzed for total C and N concentrations. Undisturbed soil core samples were also taken to determine the bulk density. Dry mass per tree was 5.6 kg for trunk, 12.0 kg f or m ain branches, 15.7 kg for lateral branches, 5.7 kg for leaves, 9.8 kg for fruits, and 10.5 kg for roots. Total amounts of C and N per tree were respectively 2.6 and 0.02 kg for trunk, 5.5 and 0.04 kg for main branches, 7.2 and 0.07 kg for lateral branches, 2.6 and 0.11 kg for leaves, 4.0 and 0.03 kg for fruit, and 4.8 and 0.05 kg for roots. Carbon and N stocks stored in the soil per hectare were 155.7 and 14.0 Mg, respectively, while those contained in pear trees were 17.8 and $0.2Mg{\cdot}ha^{-1}$ based on a tree density of 667 trees/ha. Overall, C and N stocks per hectare stored in the pear orchard were 173.6 and 14.2 Mg, respectively. Compared with results obtained in 2012, the amounts of C stocks have increased by $17.7Mg{\cdot}ha^{-1}$, while those of N stocks remained virtually unchanged ($0.66Mg{\cdot}ha^{-1}$).

• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.391-402
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• 2003

Last 20 years have witnessed many studies dealing with effects of elevated $CO_2$ on terrestrial ecosystems. However, fewer efforts have been made to elucidate effects on wetland ecosystems, although they play a key role in global biogeochemical cycles. This review synthesizes published data to reveal effects of elevated $CO_2$ on wetland plants. In particular, we focused on the changes in primary production, community structures, evapotranspiration, and nutrients in plants. Many studies have reported increases in primary production in individual plants, but we could not conclude that this will lead to increases in carbon sequestration in wetland ecosystems. The reasons include transport of photosynthates into belowground parts, speciesspecific responses, interaction among different species, and limitation of other nutrients. However, elevated $CO_2$ increased transpiration rates in many wetland plants, suggesting substantial influences on water budgets of wetlands. In addition, similar to terrestrial ecosystems, elevated $CO_2$ increased C/N ratio of many plants, which may impede organic matter decomposition in the long term. However, further information on dynamics of belowground carbon supplied from wetland plants is warranted to assess effects of elevated $CO_2$ on wetland carbon cycle accurately.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.4
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• pp.81-99
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• 2015

The acceleration of global warming has required better understanding of carbon cycles over local and regional areas such as the Korean peninsula. Since forests serve as a carbon sink, which stores a large amount of terrestrial carbon, there has been a demand to accurately estimate such forest carbon sequestration. In Korea, the National Forest Inventory(NFI) has been used to estimate the forest carbon stocks based on the amount of growing stocks per hectare measured at sampled location. However, as such data are based on point(i.e., plot) measurements, it is difficult to identify spatial distribution of forest carbon stocks. This study focuses on urban areas, which have limited number of NFI samples and have shown rapid land cover change, to estimate grid-based forest carbon stocks based on UNFCCC Approach 3 and Tier 3. Land cover change and forest carbon stocks were estimated using Landsat 5 TM data acquired in 1991, 1992, 2010, and 2011, high resolution airborne images, and the 3rd, 5th~6th NFI data. Machine learning techniques(i.e., random forest and support vector machines/regression) were used for land cover change classification and forest carbon stock estimation. Forest carbon stocks were estimated using reflectance, band ratios, vegetation indices, and topographical indices. Results showed that 33.23tonC/ha of carbon was sequestrated on the unchanged forest areas between 1991 and 2010, while 36.83 tonC/ha of carbon was sequestrated on the areas changed from other land-use types to forests. A total of 7.35 tonC/ha of carbon was released on the areas changed from forests to other land-use types. This study was a good chance to understand the quantitative forest carbon stock change according to the land cover change. Moreover the result of this study can contribute to the effective forest management.

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.605-610
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• 2008

This study was carried out to investigate the short-term (3 years) effect of thinning on aboveground carbon storage for 34-year-old (site 1) and 45-year-old (site 2) Korean pine (Pinus koraiensis Siebold et Zuccarini) plantations with different diameter class and site quality located in Gwangneung experimental forest. Thinning was manually carried out in consideration of basal area in 2004 (site 1 : 30% and 60% of basal area removed and site 2 : 60% of basal area removed). In 2004 and 2007, DBH and tree height were measured to analyze the changes in carbon storage after thinning. In the sites of 60% of basal area removed, although the mean DBH of site 1 was higher than that of site 2, mean annual carbon storage increment in site 2 ($6.5Mg\;C\;ha^{-1}yr^{-1}$) was about 3 times higher than that in site 1 ($2.3Mg\;C\;ha^{-1}yr^{-1}$). The reason for this result was probably due to higher stem density and site quality in site 2 compared to site 1. In site 2, mean annual carbon storage increment in thinned plot ($6.5Mg\;C\;ha^{-1}yr^{-1}$) was about 1.3 times higher than that in control ($5.2Mg\;C\;ha^{-1}yr^{-1}$). The results suggest that the stem density and site quality may be much more related to the aboveground carbon storage compared to diameter class. In addition, it is needed to consider these two factors for determining whether thinning is a feasible management alternative for the increase in aboveground carbon sequestration.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.73-82
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• 2023

This study was conducted to investigate the effect of soil physico-chemical properties and crop growth responses for application of biochar derived from substrate with post harvest of oyster mushroom. The biochar was produced at 450~600℃ using a top-light up draft gasifier (TLUD) production system. As a result of elemental analysis, the biochar used was C 76.2%, H 2.5%, N 3.2%, and H/C was 0.39, which met the international certification standards for biocarbons (IBI) below 0.7. The chemical properties were 10.1 for pH, 1.0% for P₂O₅, 1.8% for K₂O, and 2.5% for CaO. The application rates of biochar were 0, 100, 200, 300, and 500 kg/10a. For cultivation of chinese cabbage and welsh onion, soil organic matter (OM), total nitrogen (T-N), total carbon (T-C), Ex.cation K contents and cation exchange capacity (CEC) in the treatments were increased compared to the no treatment. In addition, the bulk density was lowered and the porosity was increased, improving the soil physical properties in the treated soil. The growth of chinese cabbage and green onion increased with the application of biochar, but the yields of chinese cabbage and green onion did not significantly different among the treatments. Soil carbon sequestration in the treatments enhanced with increasing the amount of biochar application. It is expected to apply the biochar derived from spent oyster mushroom substrate in the eco-friendly farm soil management, improving soil physico-chemical properties.

• Journal of Wetlands Research
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• v.26 no.2
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• pp.168-181
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• 2024

Constructed wetlands (CWs) deliver a range of ecosystem services, including the removal of contaminants, sequestration and storage of carbon, and enhancement of biodiversity. These services are facilitated through hydrological and ecological processes such as infiltration, adsorption, water retention, and evapotranspiration by plants and microorganisms. This study investigated the correlations between microbial populations, soil physicochemical properties, and treatment efficiency in a horizontal subsurface flow constructed wetland (HSSF CW) treating runoff from roads and parking lots. The methods employed included storm event monitoring, water quality analysis, soil sampling, soil quality parameter analysis, and microbial analysis. The facility achieved its highest pollutant removal efficiencies during the warm season (>15℃), with rates ranging from 33% to 74% for TSS, COD, TN, TP, and specific heavy metals including Fe, Zn, and Cd. Meanwhile, the highest removal efficiency was 35% for TOC during the cold season (≤15℃). These high removal rates can be attributed to sedimentation, adsorption, precipitation, plant uptake, and microbial transformations within the CW. Soil analysis revealed that the soil from HSSF CW had a soil organic carbon content 3.3 times higher than that of soil collected from a nearby landscape. Stoichiometric ratios of carbon (C), nitrogen (N), and phosphorus (P) in the inflow and outflow were recorded as C:N:P of 120:1.5:1 and 135.2:0.4:1, respectively, indicating an extremely low proportion of N and P compared to C, which may challenge microbial remediation efficiency. Additionally, microbial analyses indicated that the warm season was more conducive to microorganism growth, with higher abundance, richness, diversity, homogeneity, and evenness of the microbial community, as manifested in the biodiversity indices, compared to the cold season. Pollutants in stormwater runoff entering the HSSF CW fostered microbial growth, particularly for dominant phyla such as Proteobacteria, Actinobacteria, Acidobacteria, and Bacteroidetes, which have shown moderate to strong correlations with specific soil properties and changes in influent-effluent concentrations of water quality parameters.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.60-66
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• 2006

Three differing sandstones, two synthetic and one field sample, have been tested ultrasonically under a range of confining pressures and pore pressures representative of in-situ reservoir pressures. These sandstones include: a synthetic sandstone with calcite intergranular cement produced using the CSIRO Calcite In-situ Precipitation Process (CIPS); a synthetic sandstone with silica intergranular cement; and a core sample from the Otway Basin Waarre Formation, Boggy Creek 1 well, from the target lithology for a trial $CO_2$ pilot project. Initial testing was carried on the cores at "room-dried" conditions, with confining pressures up to 65 MPa in steps of 5 MPa. All cores were then flooded with $CO_2$, initially in the gas phase at 6 MPa, $22^{\circ}C$, then with liquid-phase $CO_2$ at a temperature of $22^{\circ}C$ and pressures from 7 MPa to 17 MPa in steps of 5 MPa. Confining pressures varied from 10 MPa to 65 MPa. Ultrasonic waveforms for both P- and S-waves were recorded at each effective pressure increment. Velocity versus effective pressure responses were calculated from the experimental data for both P- and S-waves. Attenuations $(1/Q_p)$ were calculated from the waveform data using spectral ratio methods. Theoretical calculations of velocity as a function of effective pressure for each sandstone were made using the $CO_2$ pressure-density and $CO_2$ bulk modulus-pressure phase diagrams and Gassmann effective medium theory. Flooding the cores with gaseous phase $CO_2$ produced negligible change in velocity-effective stress relationships compared to the dry state (air saturated). Flooding with liquid-phase $CO_2$ at various pore pressures lowered velocities by approximately 8% on average compared to the air-saturated state. Attenuations increased with liquid-phase $CO_2$ flooding compared to the air-saturated case. Experimental data agreed with the Gassmann calculations at high effective pressures. The "critical" effective pressure, at which agreement with theory occurred, varied with sandstone type. Discrepancies are thought to be due to differing micro-crack populations in the microstructure of each sandstone type. The agreement with theory at high effective pressures is significant and gives some confidence in predicting seismic behaviour under field conditions when $CO_2$ is injected.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.623-640
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• 2013

Soil organic carbon (SOC) of soil series is necessary to calculate soil C sequestration due to IPCC default categorized by climate regions and by soil types. The 3,400 thousand data were downloaded from agricultural soil information system and analyzed to get averages of soil order, soil series, and textual family for the three different soil management practices in Korea. The SOC content was $13.3{\pm}5.38g\;kg^{-1}$ in paddy field, $13.7{\pm}7.19g\;kg^{-1}$ in upland field, and $15.2{\pm}8.22g\;kg^{-1}$ in orchard soil, respectively. As SOC in orchard was 10% greater than that in upland, orchard must be managed with applying compost. The SOCs of inceptisols, which was largely distributed in Korea, were $13.6{\pm}5.48g\;kg^{-1}$ in paddy field, $14.1{\pm}7.38g\;kg^{-1}$ in upland field, and $15.3{\pm}8.20g\;kg^{-1}$ in orchard soil, respectively. The SOCs of alfisols were $13.6{\pm}4.96g\;kg^{-1}$ in paddy field, $13.7{\pm}6.99g\;kg^{-1}$ in upland field, and $15.6{\pm}8.59g\;kg^{-1}$ in orchard soil, respectively. The SOCs of entisols were $11.7{\pm}5.16g\;kg^{-1}$ in paddy field, $12.8{\pm}7.05g\;kg^{-1}$ in upland field, and $13.7{\pm}7.81g\;kg^{-1}$ in orchard soil, respectively. The SOCs of ultisols were $12.7{\pm}4.79g\;kg^{-1}$ in paddy field, $12.7{\pm}6.22g\;kg^{-1}$ in upland field, and $16.3{\pm}8.49g\;kg^{-1}$ in orchard soil, respectively. The fact that soils containing greater clay content in textual family had also more SOC content revealed that SOC could be also dependent on some soil properties as well as soil order. Because SOC differences among soil series representing same textual family were greater than those among textual family, SOC differences should be mainly affected by management practices such as compost application.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.65-74
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• 2020

BACKGROUND: Soil carbon sequestration has been investigated for a long time because of its potential to mitigate the greenhouse effect. No- or reduced tillage, crop rotations, or cover crops have been investigated and practiced to sequester carbon in soils but the roles of soil biota, particularly microorganisms, have been mostly ignored although they affect the amount and stability of soil organic matters. METHODS AND RESULTS: In this study we analyzed the organic matter and microbial community in organically cultivated corn field soils where no-tillage (NT) or conventional tillage (CT) had been practiced for about three years. The amounts of organic matter and recalcitrant carbon pool were 18.3 g/kg dry soil and 4.1 g C/kg dry soil, respectively in NT soils, while they were 12.4 and 2.5, respectively in CT soils. The amounts of RNA and DNA, and the copy numbers of bacterial 16S rRNA genes and fungal ITS sequences were higher in NT soils than in CT soils. No-tillage treatment increased the diversities of soil bacterial and fungal communities and clearly shifted the bacterial and fungal community structures. In NT soils the relative abundances of bacterial phyla known as copiotrophs, Betaproteobacteria and Bacteroidetes, increased while those known as oligotrophs, Acidobacteria and Verrucomicrobia, decreased compared to CT soils. The relative abundance of a fungal phylum, Glomeromycota, whose members are known as arbuscular mycorrhizal fungi, was about two time higher in NT soils than in CT soils, suggesting that the higher amount of organic matter in NT soils is related to its abundance. CONCLUSION: This study shows that no-tillage treatment greatly affects soil microbial abundance and community structure, which may affect the amount and stability of soil organic matter.