• 한국대기환경학회지
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• 제20권6호
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• pp.749-758
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• 2004

Nitrous oxide ($N_2$O) has been known as an important trace gas due to the greenhouse gas and the major source of stratospheric oxide of nitrogen (NO). Soil is the major source of $N_2$O in nature. The physicochemical characteristics of soils affect the emission of $N_2$O from soil. These physicochemical parameters are soil moisture, soil temperature, and soil N content. Since these parameters are correlated to the flux of $N_2$O from soil individually and compositely, there still remain many unknowns in the mechanism to produce $N_2$O in soil and the roles of such physicochemical parameters which affect the soil $N_2$O emission. Soil $N_2$O fluxes were measured at different levels in water filled pore space (WFPS), soil temperature and soil N contents from the same amounts of soils which were sampled from agriculturally managed upland field in a depth of ～30 cm at Kunsan. The soil $N_2$O flux measurements were conducted in a laboratory with a closed flux chamber system. The optimum soil moisture and soil temperature were observed at 60% of WFPS and ～13$^{\circ}C$. The soil $N_2$O flux increased as soil N contents increases during the whole experimental hours (up to 48 hours). However, average $N_2$O flux decreased after ～30 hours when organic carbon was mixed with nitrogen in the sample soils. It is suggested that organic carbon could be important for the emission of $N_2$O, and that the ratio of N to C needs to be identified in the process of $N_2$O soil emission.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1517-1526
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• 2018

Investigating bacterial diversity and its metabolic capabilities is crucial for interpreting the ecological patterns in a desert environment and assessing the presence of exploitable microbial resources. In this study, we evaluated the spatial heterogeneity of physicochemical parameters, soil bacterial diversity and metabolic adaptation at meter scale. Soil samples were collected from two quadrats of a desert (Thar Desert, India) with a hot, arid climate, very little rainfall and extreme temperatures. Analysis of physico-chemical parameters and subsequent variance analysis (p-values < 0.05) revealed that sulfate, potassium and magnesium ions were the most variable between the quadrats. Microbial diversity of the two quadrats was studied using Illumina bar-coded sequencing by targeting V3-V4 regions of 16S rDNA. As for the results, 702504 high-quality sequence reads, assigned to 173 operational taxonomic units (OTUs) at species level, were examined. The most abundant phyla in both quadrats were Actinobacteria (38.72%), Proteobacteria (32.94%), and Acidobacteria (9.24%). At genus level, Gaiella represented highest prevalence, followed by Streptomyces, Solirubrobacter, Aciditerrimonas, Geminicoccus, Geodermatophilus, Microvirga, and Rubrobacter. Between the quadrats, significant difference (p-values < 0.05) was found in the abundance of Aciditerrimonas, Geodermatophilus, Geminicoccus, Ilumatobacter, Marmoricola, Nakamurella, and Solirubrobacter. Metabolic functional mapping revealed diverse biological activities, and was significantly correlated with physicochemical parameters. The results revealed spatial variation of ions, microbial abundance and functional attributes in the studied quadrats, and patchy nature in local scale. Interestingly, abundance of the biotechnologically important phylum Actinobacteria, with large proposition of unclassified species in the desert, suggested that this arid environment is a promising site for bioprospection.

• 한국토양비료학회지
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• 제46권3호
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• pp.173-181
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• 2013

Livestock wastes are considered as major environmental pollutants because they contain high concentration of organic materials. In 2001, The Environmental Department reported that stock farmers were increasing as 5.1%/year, which resulted in a gradual increase in livestock wastes generation. The direct disposal of livestock wastes create several environmental problems. Thus, several countries banned the disposal of livestock wastes in environment including aquatic systems. Recently, aeration-based liquid fertilization was considered as potential way for the disposal of livestock wastes. In this study, next generation sequencing (NGS) analysis was used to understand the microbial community changes during liquid fertilization of livestock wastes. Microbial community was compared with liquid fertilizer physicochemical analysis such as $BOD_5$, $COD_{Mn}$ pH, N (Nitrogen), P (Phosphorus), K (Potassium) etc. The physicochemical parameters and bacterial community results pave the way for producing effective livestock-based fertilizer. By comparing the physical characteristics of the manure with microbial community changes, it is possible to optimize the conditions for producing effective fertilizer.

• Journal of Ecology and Environment
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• 제46권1호
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• pp.31-40
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• 2022

Background: Plant vegetation appears in heterogeneous and patchy forms in arid and semi-arid regions. In these regions, underneath the plant patches and the empty spaces between them are covered by biological soil crusts (moss, lichen, cyanobacteria, and fungi). Biological soil crusts lead to the formation and development of fertile islands in between vegetation patches via nitrogen and carbon fixation and the permeation of runoff water and nutrients in the soil. Results: The present study has investigated the association of biological soil crusts, the development of fertile islands, and the formation of plant patches in part of the Takht-e Soltan protected area, located in Khorasan Razavi Province, Iran. Three sites were randomly selected as the working units and differentiated based on their geomorphological characteristics to the alluvial fan, hillslope, and fluvial terrace landforms. Two-step systematic random sampling was conducted along a 100-meter transect using a 5 m² plot at a 0-5 cm depth in three repetitions. Fifteen samplings were carried out at each site with a total of 45 samples taken. The results showed that the difference in altitude has a significant relationship with species diversity and decreases with decreasing altitude. Results have revealed that the moisture content of the site, with biocrust has had a considerable increase compared to the other sites, helping to form vegetation patterns and fertile islands. Conclusions: The findings indicated that biological crusts had impacted the allocation of soil parameters. They affect the formation of plant patches by increasing the soil's organic carbon, nitrogen, moisture and nutrient content provide a suitable space for plant growth by increasing the soil fertility in the inter-patch space.

• 한국대기환경학회지
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• 제27권3호
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• pp.313-325
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• 2011

From October 2009 to June 2010, major greenhouse gases (GHG: $N_2O$, $CH_4$, $CO_2$) soil emission were measured from upland cabbage field at Kunsan ($35^{\circ}$56'23"N, $126^{\circ}$43'14"E), Korea by using closed static chamber method. The measurements were conducted mostly from 10:00 to 18:00LST during field experiment days (total 28 days). After analyzing GHG concentrations inside of flux chamber by using a GC equipped with a methanizer (Varian CP3800), the GHG fluxes were calculated from a linear regression of the changes in the concentrations with time. Soil parameters (e.g. soil moisture, temperature, pH, organic C, soil N) were also measured at the sampling site. The average soil pH and soil moisture were ~pH $5.42{\pm}0.03$ and $70.0{\pm}1.8$ %WFPS (water filled pore space), respectively. The ranges of GHG flux during the experimental period were $0.08\sim8.40\;mg/m^2{\cdot}hr$ for $N_2O$, $-92.96\sim139.38mg/m^2{\cdot}hr$ for $CO_2$, and $-0.09\sim0.05mg/m^2{\cdot}hr$ for $CH_4$, respectively. It revealed that monthly means of $CO_2$ and $CH_4$ flux during October (fall) were positive and significantly higher than those (negative value) during January (winter) when subsoil have low temperature and relatively high moisture due to snow during the winter measurement period. Soil mean temperature and moisture during these months were $17.5{\pm}1.2^{\circ}C$, $45.7{\pm}8.2$%WFPS for October; and $1.4{\pm}1.3^{\circ}C$, $89.9{\pm}8.8$ %WFPS for January. It may indicate that soil temperature and moisture have significant role in determining whether the $CO_2$ and $CH_4$ emission or uptake take place. Low temperature and high moisture above a certain optimum level during winter could weaken microbial activity and the gas diffusion in soil matrix, and then make soil GHG emission to the atmosphere decrease. Other soil parameters were also discussed with respect to GHG emissions. Both positive and negative gas fluxes in $CH_4$ and $CO_2$ were observed during these measurements, but not for $N_2O$. It is likely that $CH_4$ and $CO_2$ gases emanated from soil surface or up taken by the soil depending on other factors such as background concentrations and physicochemical soil conditions.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.354-357
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• 2004

The addition of oxygenates to diesel fuel can significantly reduce particulate emissions. Dibutyl maleate (DBM) and tripropylene glycol methyl ether (TGME) have been identified as possible additives based on their physicochemical characteristics and performance in engine test. However, their potential environmental impacts are unknown. therefore, practical considerations in the selection of an oxygenate additives should include cost, availability, compatibility with engines and fuel, and, particularly, its overall environmental impact. This study was investigated to determine optimal condition for the analysis of potential diesel oxygenates using SPME technique with GC-FID. Four fibers were compared and CAR/PDMS fiber was found to be the most sensitive when used direct-sampling. An absorption time of 30min and a desorption time of 5min provided to be the most sensitivity. The effects of experimental parameters such as the addition of salts, agitation, absorption time, compositon on the analysis were investigated. Analytical parameter such as linearity was also evaluated.

• 한국산림과학회지
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• 제111권3호
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• pp.357-364
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• 2022

본 연구는 미국의 미시간주 산지로부터 도입한 종자를 이용하여 국내 6개 지역에서의 토양 물리·화학적 성질 및 기상인자에 따른 루브라참나무 초기 생장 특성을 분석하고자 수행되었다. 조사지는 화성, 양평, 평창, 삼척, 충주, 김제이며 2014년에 루브라참나무 묘목(1-0묘)은 3,000본 ha^-1 밀도로 식재되었다. 2021년도에 조사된 6개 지역 8년생 루브라참나무의 평균 수고, 근원경 및 재적생장은 각각 3.52 m, 3.84 cm, 0.0023 m³로 나타났다. 조사된 국내 6개 지역 중에서 경기도 화성시에 식재된 루브라참나무의 생장이 가장 우수하며 강원도 평창군의 생장이 가장 저조하였다. 토양특성 조사에서 조림지 토양 내 모래의 비율은 21.4~64.1%, 미사는 24.9~61.1%, 점토는 9.7~21.2%로 확인되었으며, pH는 전체적으로 4.15~4.80의 범위로 약산성을 나타내었다. 지역별로는 화성이 4.15로 가장 낮았고 삼척 지역이 4.80으로 가장 높았다. 조림지 토양의 물리·화학적 특성 및 기상인자와 생장 특성과의 상관분석을 진행한 결과, 토양인자들 중 pH는 근원경과 부의 상관을 나타냈으며 다른 토양인자들은 생장특성과 유의한 상관관계가 나타나지 않았다. 반면, 일 최고기온과 3~10월의 평균온도 등의 기상인자는 생장특성과 강한 정의 상관을 나타냈으며, 해발고와 지형, 3~10월의 강우 일수는 부의 상관을 보였다. 특히 화성지역은 가장 높은 일 최고온도와 3~10월의 평균온도, 낮은 고도와 산록에 가까운 지형으로 인해 가장 우수한 초기생장을 보이는 것으로 나타났다. 생장이 가장 저조했던 평창의 경우 높은 고도와 낮은 일 최저기온 등으로 인한 겨울철 동해 피해와 야생동물에 의한 수목 피해가 생장에 부정적인 영향을 주었던 것으로 분석되었다. 주성분 분석에서는 제 3 주성분까지 84.7%의 설명력을 나타냈으며, 생장특성인 근원경 및 재적과 생장이 가장 우수했던 화성지역이 강한 상관관계를 보였다. 종합적으로 국내 6개 지역 중에서 화성 지역의 루브라참나무 초기 생장이 가장 우수한 것으로 나타났으며, 조림지 토양의 물리·화학적 특성보다는 온도나 고도와 같은 기상과 관련된 인자가 생장특성과 상관관계가 높다는 것을 확인할 수 있었다. 이 결과는 루브라참나무 국내 조림 적지 판정 및 환경 특성에 따른 초기생장 특성 예측에 필요한 유용한 정보로 이용될 수 있을 것으로 판단된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권6호
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• pp.47-57
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• 2022

A number of different methods have been used for modeling the sorption of volatile organic chlorinated compounds such as tetrachloroethylene/perchloroethylene (PCE). In this study, PCE was adsorbed in several natural sorbents, i.e., Pahokee peat, vermicompost, BionSoil^®, and natural soil, in the batch experiments. Several sorption models such as linear, Freundlich, solubility-normalized Freundlich model, and Polanyi-Manes model (PMM) were used to analyze sorption isotherms. The relationship between sorption model parameters, organic carbon content (f_oc), and elemental C/N ratio was studied. The organic carbon normalized partition coefficient values (log K_oc = 1.50-3.13) in four different sorbents were less than the logarithm of the octanol-water partition coefficient (log K_ow = 3.40) of PCE due to high organic carbon contents. The log K_oc decreased linearly with log f_oc and log C/N ratio, but increased linearly with log O/C, log H/C, and log (N+O)/C ratio. Both log K_F,oc or log K_F,oc decreased linearly with log f_oc (R² = 0.88-0.92) and log C/N ratio (R² = 0.57-0.76), but increased linearly with log (N+O)/C (R² = 0.93-0.95). The log q_max,oc decreased linearly as log f_oc and log C/N increased, whereas it increased with log O/C, log H/C and log (N+O)/C ratios. The log q_max,oc increased linearly with (N+O)/C indicating a strong dependence of q_max,oc on the polarity index. The results showed that PCE sorption behaviors were strongly correlated with the physicochemical properties of soil organic matter (SOM).

• Geomechanics and Engineering
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• 제1권4호
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• pp.291-306
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• 2009

One-dimensional soil-column studies were carried out to understand the interaction of three industrial effluents namely amino acid ('highly acidic'), surfactant ('highly organic') and pharmaceutical ('organic and toxic') on the physicochemical behavior, index properties and shear strength of bentonite due to artificial contamination extending to nearly 300 days. Changes in inorganic and organic pollutants present in the effluents due to the interaction of the above effluents and soil were assessed to understand the physico-chemical behaviour. Batch and continuous modes of operation, 8 hrs and 16 hrs Hydraulic Retention Time [HRT] and 25%, 50% concentrations of effluents, were the parameters considered. Amino acid, surfactant and pharmaceutical effluents have shown a high variation in pH (7 to 8) after artificial contamination on bentonite that is their original characteristics of the above effluents have been completely reversed. Further, it is found that the shear strength of bentonite has reduced by about 20%, and with respect to liquid limit and plastic limit shows an increasing trend with time within the period of contamination.

• 대한환경공학회지
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• 제33권12호
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• pp.861-867
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• 2011

새만금호로 유입되는 만경강과 동진강의 하상 퇴적물의 오염도를 파악하기 위하여, 퇴적물 중 강열감량, COD, 총질소, 총인 및 중금속(As, Cd, Cr, Pb, Zn)의 농도를 분석하였다. 강열감량, COD, 총인의 농도는 각각 평균 2.40 (${\pm}2.18$)%, 2.97 (${\pm}3.06$)mg/g sediment, 0.370 (${\pm}0.351$) mg/g sediment이었으며, 이들 물질에 의한 퇴적물의 오염도가 높지 않았다. 하지만 2008년에 비해 2009년의 시료에서 농도가 증가하였으며, 이러한 결과는 퇴적물의 오염이 점진적으로 진행되고 있음을 의미한다. 총질소의 경우에는 0.59~13.11 mg/g sediment로 채취 지점 및 채취 시기에 따라 변이가 컸으며, 국내 하천 및 호소의 퇴적물 준설 기준과 비교할 때, 질소 오염이 심한 것으로 나타났다. 이러한 결과는 새만금호의 수질을 유지하기 위하여 만경강과 동진강의 질소오염의 원인을 파악하고 대책의 수립이 필요함을 의미한다. 중금속의 경우에는 크롬을 제외하고 토양오염우려기준을 초과하지 않아 오염이 일어나지 않은 것으로 판단된다. 크롬의 경우, 만경강 상류의 일부 지역에서 우려기준을 초과하는 높은 농도가 측정되어, 이에 대한 원인 분석과 대책 수립이 필요한 것으로 판단된다.