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This study was conducted to investigate variations in the stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) of agricultural soils under different land uses (i.e., paddy, upland, and orchard) that subjected to different fertilization management (i.e., 15 N-depleted synthetic fertilizer and 13C- and 15 N-enriched livestock manure and compost application). Soil samples were collected from paddy, upland, and orchard fields in an intensive agricultural area, and forest (pine and oak) soils were additionally included as background soils. The C and N concentrations and isotope ratios of both bulk and water-extractable soil fractions were analyzed. The δ13C and δ15N of agricultural soils were higher than those of forest soils, reflecting repeated manure and compost applications (for both δ13C and δ15N) and higher N loss (for δ15N) in agricultural soils. Among agricultural soils, orchard (− 24.2‰ for δ13C and + 10.6‰ for δ15N) and upland (− 25.4‰ and + 9.6‰, respectively) soils which received higher rates of manure and compost were more enriched with 13C and 15N compared with paddy (− 28.0‰ and + 4.9‰, respectively). Such differences in the isotopic compositions among agricultural soils were also found for water-extractable soil fractions. Our study suggests that δ13C and δ15N of agricultural soils are affected by land use types with different fertilization management, particularly application of 13C- and 15 N-enriched livestock manure and compost. The δ13C and δ15N could be used as chemical indicators to evaluate the effects of the application of manure and compost on soil C and N dynamics.

In intensive agricultural watersheds, riverine particulate organic matter (POM) may be transported from many sources such as rice paddies, crop uplands, forests, and livestock farming areas during rainy seasons. However, the impacts of land-use and rainfall changes on the POM sources are not well understood. In this study, changes in the sources of riverine POM were investigated in an agricultural area of Korea between 2014 and 2020/21. During this period, land-use and rainfall patterns changed dramatically. The δ

We herein describe a novel washing-free electrochemical strategy for target DNA detection by utilizing the peroxidase mimicking DNAzyme. The DNAzymeincorporated DNA probes, the key components of this strategy, are designed to be not able to form G-quadruplex structure in the initial state such that the peroxidase mimicking activity of DNAzyme is kept suppressed. The DNAzyme sequences, however, would be converted to the catalytically active G-quadruplex structure by the presence of target DNA, whose peroxidase mimicking activity then promote the precipitation reaction of 4-chloronaphthol (4-CN) on the electrode. Due to the precipitates produced on the electrode surface, the electrochemical reaction between the redox materials and electrode surface is inhibited, consequently leading to a significant increase of the impedance signal. Based on this novel electrochemical design principle, we successfully detected the target DNA from sexually transmitted disease (STD) pathogens such as Chlamydia trachomatis, Trichomonas vaginalis, and Herpes simplex virus type 2 in real patient samples, verifying its practical diagnostic capability in the clinical applications.

We compared the patterns of natural abundance of nitrogen (N) isotope ratio (δ15N) of total soil N among cropland, forest, and grassland soils, with special interests in the effects of farming system on cropland and grassland, and climate zone on forest soils, as well as the general effect of land-use change and site disturbance. We analyzed data on δ15N of terrestrial N sources (n = 532), cropland (n = 168), forest (n = 227 for organic and 428 for mineral soil layers), and grassland soils (n = 624). Forest soils had the lowest δ15N (– 1.0 ± 0.2‰ and + 3.1 ± 0.2‰ for mineral and organic soil layers, respectively), reflecting the influence of the 15N-depleted source N and the more closed nature of the N cycle. Tropical forest soil had higher δ15N than other climate zones, reflecting the influence of the high N availability and loss in tropical forests. The low δ15N in subtropical forest soils likely reflected the influence of the high rate of deposition of 15N-depleted N. The δ15N of cropland (+ 5.0 ± 0.2‰) and grassland (+ 6.2 ± 0.1‰) soils was greater with manure than with synthetic fertilizer applications. Soil δ15N was also affected by land-use change and was often increased (followed by progressive decreases) by site disturbance. Land-use type and land management effects on soil δ15N reflect changes in both the N sources and loss, while land disturbance effects are primarily associated with the degree of N loss. We also conclude that subtropical forest soil δ15N is affected by the high rate of atmospheric N deposition.

Rice residue including root and straw are unique carbon (C) source in paddy soils. However, the potential changes in quantity and chemical composition of rice residue under co-elevated atmospheric CO2 concentration ([CO2]) and air temperature (Tair) and the legacy effect of the changed chemical composition on residue decomposition have not been investigated. This study was conducted to investigate biomass, chemical composition, and decomposability of rice root and straw produced under elevated [CO2] and Tair. Root and straw biomass increased by elevated [CO2] and elevated Tair, respectively, and the greatest biomass was achieved under co-elevated [CO2]-Tair for both root and straw. The concentration of lignin (recalcitrant) decreased while that of nonstructural carbohydrates (less recalcitrant) increased by co-elevated [CO2]-Tair. The ratio of lignin-to-nitrogen (lignin/N) decreased by co-elevated [CO2]-Tair compared to ambient [CO2]-Tair due to increased N and decreased lignin concentrations. Decomposability of root (lignin/N, 36.4) produced under co-elevated [CO2]-Tair was greater than that under ambient co-elevated [CO2]-Tair (lignin/N, 53.7); however, there was no difference in decomposability for straw, which had relatively narrow range of lignin/N (27.3–36.5) regardless of [CO2]-Tair conditions. The results of this study provide a novel insight into the changes in quantity and quality of rice residue under elevated [CO2]-Tair that are necessary to predict changes in paddy soil C sequestration under global warming.

The properties of secondary salt-affected soils developed from improper irrigation and drainage management and their effects on rice growth and yield are well documented. However, relevant informat...

We herein described a rapid, sensitive, and selective colorimetric sensing platform for biothiols in human serum, which relies on the dual functions of biothiols as anti-etching and aggregating agent for silver nanoprisms (AgNPRs). In principle, the target biothiols that bind to the surface of AgNPRs through Ag–S covalent interactions protect the AgNPRs from being etched by chloride ion (Cl−) in human serum, thus exhibiting the blue/purple color that is indicative of AgNPRs. On the other hand, the color of AgNPRs turned to yellow in the absence of biothiols or the presence of non-sulfur-containing amino acids, indicating the formation of small silver nanoparticles (AgNPs). Importantly, we found that individual biothiols (Hcy, Cys, and GSH) exert not only the anti-etching effect, but also the aggregating effect on AgNPRs, which can be modulated by simply tuning the pH conditions, and this consequently allows for the discriminative detection of each biothiol. Based on this simple and cost-effective strategy, we successfully determined the Hcy, Cys, and GSH in human serum with high sensitivity and selectivity within 10 min, demonstrating the diagnostic capability and potential in practical applications.

Soil surface with crop residue is effective in reducing soil erosion and carbon (C), nitrogen (N), and phosphorus (P) losses from sloping fields. However, there is a high possibility that surface cover increases export of dissolved organic C (DOC) though relevant field studies under natural rainfall are lacking. In this study, the effects of surface cover with rice (Oryza sativa L.) straw on soil and CNP losses in both dissolved and sediment-bound forms from maize (Zea mays L.) fields were investigated under two fertilization levels (standard and double) × two types of runoff experiments (natural rainfall and artificial irrigation). Changes in soil properties including moisture, temperature, nutrients, and C concentration as well as maize yield were also examined. Surface cover decreased soil and total CNP losses by up to 82% across the experimental plots with some exceptions. However, surface cover increased DOC export in both natural (by 68-82% in total across all events) and artificial (by 3-4 fold) runoff, suggesting that crop residue cover may act as a DOC pollution source of water bodies. The contribution of rice straw to DOC, which was calculated using the δ

Forest decline due to atmospheric pollution is a consequence of long-term chronic exposure, and thus chemical proxies that are sensitive to the pollution are helpful in estimating the impact of atmospheric pollution on forest health. In this study, we explored changes in the isotopic and elemental compositions of needles of red pine (Pinus densiflora) with varying precipitation pH and concentrations of NO2 and SO2 across 18 cities to identify isotopic and chemical signatures that are sensitive to acid deposition. The cities had different intensity of traffic and industrial activities, and thus were expected to have varying levels of atmospheric pollution. The pine needles were analyzed for carbon (δ13C) and nitrogen (δ15N) isotope ratios, N concentrations, C-to-N ratio (C/N), and calcium-to-aluminum ratio (Ca/Al). Analysis of variance, simple linear correlation, and redundancy analysis were used to investigate the variations in foliar chemistry with atmospheric variables. Neither NO2 nor SO2 concentration was correlated with foliar δ13C, δ15N, N concentration, and C/N; whereas precipitation pH was correlated with the foliar parameters, suggesting that foliar chemistry is more sensitive to total acidifying materials than to individual pollutant. The foliar δ13C decreased with lowered precipitation pH, reflecting the increased 13C-depleted CO2 that was co-emitted with acidifying materials from fossil fuel combustion. Foliar δ15N decreased and foliar N concentration increased with lowered precipitation pH, indicating tree uptake of 15N-depleted N from acid deposition. Accordingly, the C/N ratio also decreased with lowered precipitation pH. However, there was no relationship between foliar Ca/Al and precipitation pH; rather. Our result suggests that δ13C, δ15N, N concentration, and C/N of pine needle samples are associated with the level of precipitation pH and thus pine needles could be used as bio-indicators of the impacts of total acidifying pollutants on forest.

Lead (Pb) sorption capacity (PbSmax) and distribution in chemical and particle-size fractions of six soils with different physico-chemical properties were investigated to explore the principal properties of soils that affect Pb sorption. A series of experiments of Pb sorption and soil chemical and particle-size fractionation of sorbed Pb were conducted with six soils of different texture, mineralogy, organic matter concentration, cation exchange capacity (CEC), and Fe-Mn concentrations. Soils either developed from volcanic ash or containing smectite showed relatively higher PbSmax than the other soils. Across the soils, clay content, organic matter concentration, and total Fe concentrations were significantly (p

The long-term precipitation of the σ phase in a 304H austenitic stainless steel, which had been used for an oil refinery system at 720 °C for 18 years, was investigated in terms of both the base and weld metals using experimental and computational methods. The microstructure was quantitatively analyzed using the electron backscattered diffraction (EBSD) technique, which clearly revealed a substantial amount of σ phase formed at the expense of δ ferrite during the service. Whereas the amount of σ phase precipitated after service corresponded to the fraction of the initial δ ferrite in the base metal, the fraction of the σ phase significantly exceeded the initial amount of δ ferrite in the weld metal. The simulation of long-term precipitation kinetics using MatCalc indicated that the nucleation of the σ phase occurred only in the δ ferrite in both the base and weld metals. The subsequent growth of the σ phase after the nucleation in δ ferrite was predicted to actively occur in austenite during the service. The simulation results also implied that the precipitation behavior of the σ phase was very sensitive to the Cr content.

Synthetic fertilizers and raw or composted livestock manure are typical nitrogen (N) sources in intensive cropping and livestock-farming systems. The distinct N isotope ratios (15N/14N, expressed as δ15N) of the N sources make it possible to use the δ15N of soil, plant and groundwater samples to trace the N derived from the two N sources in the agricultural landscape. However, N isotope fractionation during N cycling may hamper the usefulness of the δ15N technique for tracing N. This paper reviews the changes in the δ15N of soil, plant and groundwater samples in the agricultural landscape as affected by synthetic fertilizer and raw or composted manure applications with consideration of the effect of N source and N fractionation during N cycling on variations in δ15N. First, this review summarizes the fundamental N isotope fractionation theory with an emphasis on the critical role of nitrification in changing δ15N through N loss. Second, the differences in the δ15N of synthetic fertilizer and raw or composted manure are discussed with an emphasis on mechanisms that increase δ15N in raw or composted manure. Third, the effects of synthetic fertilizer and raw or composted manure applications on the variations of δ15N in soil, plant and groundwater samples across different scales of experiments from laboratory to watershed are discussed. We conclude that in spite of N isotope fractionation, the feasibility of the δ15N technique in tracing N originated from synthetic fertilizer and raw or composted manure in soil, plant and groundwater in the agricultural landscape can be strengthened when site-specific information on the δ15N of N sources as well as the dominant N processes is available.

The effects of increased nitrogen (N) availability through atmospheric deposition on the quantity and quality of tree leaf litter have been widely reported. However, such N effects under co-elevated CO2 concentration ([CO2]) and air temperature (Tair) have not been investigated. In this study, changes in biomass and chemistry of litter of Pinus densiflora S. et Z. (pine) and Quercus variabilis Blume (oak) saplings with two levels of each N × [CO2] × Tair were investigated for two growing seasons. The levels of N, [CO2], and Tair were 2 and 6-fold of ambient N deposition, ambient and ambient + 285 ppmv, and ambient and ambient + 2.2 °C, respectively, on average across the two seasons. The concentrations of N, minerals, and carbon (C) compounds such as non-structural carbohydrate (NSC) and lignin as well as stoichiometry such as the ratio of C to N (C/N) and lignin to N (lignin/N) of litter were analyzed to determine litter chemistry. In addition, the legacy effect of changed chemistry on microbial decomposability of the litters were also assessed by measuring CO2 emission in a 60-day lab incubation experiment. The effect of high N addition on increasing litter production was consistent regardless of [CO2] and Tair for oak; however, for pine, N-induced increases in litter production were negated under elevated [CO2] and/or Tair, probably due to efficient uptake and use of N by pine under elevated [CO2] as well as lowered N demand via warming-induced stress under elevated Tair. High N-induced decreases in C/N and lignin/N was consistent across [CO2]-Tair combination for both species though other chemical components such as NSC and minerals including phosphorous, calcium, aluminum, and manganese varied inconsistently. The CO2 emission from the soils amended with litters of different chemistry was not correlated with litter chemistry, suggesting that changed litter chemistry under different N level × [CO2] × Tair may not affect litter decomposability in the soils. This study enlarges our understanding of the effect of increased N availability on litter quantity, chemical composition, and microbial decomposability under different [CO2] and Tair. However, a study with mature trees in a natural forest stand should further improve our understanding.

Efficient refinery start-up and shutdown durations are vital in establishing prolonged productivity in refineries operating hydrotreating reactors. The benefits of efficient start up and shutdown cycles are extensive, and include considerable operational and cost reduction. Reduced start-up and shutdown cycles, however, require increased heating and cooling rates, which cause higher temperature gradients throughout the reactor vessel, consequently leading to higher thermal stresses, which may affect damage mechanisms and limit reactor’s life. The equipment’s OEM has defined guidelines for the reactor heating and cooling during start-up and shutdown cycles and any attempt to reduce the start-up and shutdown duration is usually limited by these guidelines. It is therefore necessary to carry out an engineering assessment to determine the effect of changing the start-up and shutdown procedures beyond the OEM guidelines on reactor’s life. Multiple thermo-mechanical Finite Element analyses for a series of different start-up/ shutdown procedures, including the current procedure, were carried out to determine the through-wall thermal gradient and stresses, and identify the most critical locations. In order to estimate convective heat transfer coefficients, Computational Fluid Dynamic (CFD) analysis was utilized to describe the complex fluid flow behavior of the feedstock in the presence of catalysts and internal geometry features. Low Cycle Fatigue (LCF) was adopted as a main damage mechanism to quantify the damage as a result of the changed operating conditions. It was determined that the LCF life calculated in the reactor vessel’s critical damage locations was found to be sufficiently long with respect to the frequency of start/shutdown cycles, even with operating conditions exceeding the OEM limit. Therefore, alternative guidelines were suggested to achieve the time reduction in startup/shutdown operation by increasing ramp rates without compromising structural integrity of the vessel.

To better predict forest productivity under rising atmospheric CO 2 concentration ([CO 2 ]), it is critical to understand how intrinsic water-use efficiency (WUE i ) and its relationship with tree growth are affected by the concomitant changes in environmental conditions such as precipitation, temperature, and air pollution that either enhance or undermine any potential CO 2 fertilization effect. We investigated changes in δ 13 C and WUE i in annual rings and basal area increment (BAI) of Pinus densiflora (from 1968 to 2007) and Quercus variabilis (from 1970 to 2007) trees in relation to precipitation, temperature, and air pollution in a humid temperate forest. The WUE i of P. densiflora increased by 39.9%, whereas that of Q. variabilis did not change over time in the study period. The WUE i was not affected by precipitation for both species but increased ( P P. densiflora and with SO 2 emissions for both species. Multiple regression models suggested that the effect of [CO 2 ] on tree growth was much higher than temperature; however, for the period (1998 to 2007) when SO 2 emissions data were available, SO 2 emission was the driver of changes in BAI and WUE i , and temperature effects became stronger than [CO 2 ]. Overall, BAI and WUE i were positively ( P P. densiflora , but not for Q. variabilis . We conclude that temperature and air pollution rather than precipitation were key determinants of WUE i at the study site and that the two species had contrasting responses to environmental changes.

Historical growth response of Quercus variabilis, which is the most important deciduous timber species in Korea, was investigated using the width and C isotope ratio (13C/12C denoted as δ13C) of the annual ring from 1975 to 2007. Tree disks were collected from three Q. variabilis trees with different growth statuses from a site in the Mt. Naejang area, and analyzed for annual ring width and δ13C. Basal area increment (BAI) of the annual ring was calculated from the width data, and carbon isotope discrimination (Δ) was calculated using δ13C. The intercorrelations among BAI, Δ, and environmental variables were explored. The BAI was positively (p

Only limited information is available in the research area on the effect of elevated CO2 concentration ([CO2]) and air temperature (Tair) on the fertilizer N uptake by rice. This study was conducted to investigate changes in rice uptake of N derived from fertilizer (NDFF) and soil (NDFS) as well as fertilizer N uptake efficiency (FUE) with elevated [CO2] and Tair in two soils with different fertility. Rice (Oryza sativa L.) plants were grown with 15N-urea for two growing seasons (2007 in the less fertile and 2008 in the more fertile soil) in temperature gradient chambers under two (ambient and elevated) levels of [CO2] and Tair regimes. At harvest, dry matter (DM) and N uptake amount of rice compartments (root, shoot, and grain) were determined. The DM of whole rice increased (P

Despite the importance of dissolved organic N (DON) in wet precipitation, the N isotope ratio (δ 15 N) of DON has rarely been reported when compared to those of inorganic N (NH 4 + and NO 3 − ). This study was conducted to investigate seasonal variation of δ 15 N of DON in comparison with the δ 15 N of NH 4 + and NO 3 − during wet precipitation in a metropolis area that is surrounded by agricultural areas in southern Korea. For two years (2007 and 2008), all effective precipitation events (>5 mm) were collected and the δ 15 N of NH 4 + , NO 3 − , DON, and total N were analyzed, and the volume-weighted monthly mean N deposition and δ 15 N were calculated. The contribution of DON to total N deposition (41.0 and 37.3% in 2007 and 2008, respectively) was compatible to that of NH 4 + and two times higher than that of NO 3 − . The annual mean δ 15 N of DON (0.3 and 0.2‰ in 2007 and 2008, respectively) was higher than that of NH 4 + (−3.0 and −6.8‰, respectively) but similar to that of NO 3 − (1.5 and −0.5‰, respectively). The seasonal pattern of molar ratio of NH 4 + /NO 3 − in combination with δ 15 N of NH 4 + and NO 3 − indicated that there were multiple diffuse sources of N deposition presented and seasonal shifting of main sources of N deposition occurred in the study site. These sources included fertilized agricultural fields in the spring and early summer, livestock excrements in the middle summer and fall, and coal-fired boilers in the winter. The intimate relationship between DON and NH 4 + in terms of % portion in total N and their δ 15 N suggested that the source of DON was closely coupled with that of NH 4 + ; e.g. fertilizer and livestock excretion. A direct measurement of N species emitted from fertilized agricultural field and livestock manure is necessary to confirm the source of DON.

Nitrogen isotope abundance (δ 15N) of paddy rice (Oryza sativa L.) grown for 110 days after transplanting (DAT) under field conditions with ammonium sulfate (AS with −0.4‰ as a synthetic fertilizer), pig manure compost (PMC with 15.3‰ as a livestock manure compost), and hairy vetch (HV with −0.5‰ as a green manure) was investigated to test the possible use of δ 15N technique in discriminating organically grown from conventionally grown rice. At 15 DAT, the δ 15N of whole rice decreased (P 5.5‰ for control (without N input) > 4.0‰ for HV > 1.8‰ for AS. This difference seemed to reflect primarily the δ 15N signal of N sources. Although differences in δ 15N of rice grown with isotopically distinct N inputs (i.e. PMC vs. AS and PMC vs. HV) became smaller over time, the difference (2.8 and 3.0‰ difference at harvest on 110 DAT, respectively) was still significant (P

Carbon isotope ratio ( 13 C/ 12 C, expressed as δ 13 C) of tree ring can be proxy of atmospheric CO2 concentration ((CO2)) due to the inter-correlation between atmospheric (CO2), δ 13 C of atmospheric CO2, and δ 13 C of plant tissue that assimilates atmospheric CO2. This study was conducted to investigate if δ 13 C of tree ring of Pinus densiflora in polluted area may show a lower value than that in unpolluted area and to explore the possibility of reconstructing atmospheric (CO2) using its relationship with δ 13 C of tree ring. During the period between 1999 and 2005, δ 13 C of tree annual ring tended to decrease over time, and the δ 13 C in polluted area (-27.2‰ in 2009 to -28.3‰ in 2005) was significantly (P

Effects of elevated CO2 concentration ([CO2]) and air temperature (Tair) on accumulation and intra-plant partitioning of dry matter (DM) and nitrogen in paddy rice were investigated by performing a pot experiment in six natural sunlit temperature gradient chambers (TGCs) with or without CO2 fumigation. Rice (Oryza sativa L.) plants were grown in TGCs for a whole season under two levels of [CO2] (ambient, 380 ppm; elevated, 622 ppm) and two daily Tair regimes (ambient, 25.2°C; elevated, 27.3°C) in split-plot design with triplication. The effects of elevated [CO2] and Tair on DM were most dramatic for grain and shoot with a significant (P

To test the possible use of tree ring chemical properties as proxies for precipitation acidity ([H+]), we investigated the relationships between tree ring chemistry (δ13C, δ15N, Ca-to-Al ratio, and N concentration) of Pinus densiflora and precipitation [H+] between 1992 and 2005 in an industrial area in the southwest region of South Korea. Statistical analyses showed that all tree ring chemistry parameters were significantly correlated with precipitation [H+]. Tree ring δ13C was negatively correlated with precipitation acidity (r = −0.67, P < 0.01), reflecting the photosynthetic fixation of 13C-depleted CO2 from fossil fuel combustion that would be the primary source of precipitation acidity. A positive correlation of N concentration (r = 0.89, P < 0.001) and a negative correlation of δ15N (r = −0.63, P < 0.05) in tree rings with precipitation acidity most likely reflected the influence of 15N-depleted N compounds deposited via precipitation. The Ca-to-Al ratio was negatively (r = −0.58, P < 0.05) correlated with precipitation acidity, indicating that soil acidification caused the loss of Ca from the soil and solubilization of Al resulting from acid precipitation. Such relationships suggest that δ13C, δ15N, N concentration, and Ca-to-Al ratio in tree rings can be reliably used to evaluate the impact of acid precipitation on the studied P. densiflora stands.

An understanding of the long-term changes in the nitrate contamination pattern of unconfined groundwater is critical to conservation of drinking water in rural areas supporting mixed land-use activities such as cropping, livestock farming, and residence. To examine the effect of different land-use activities on nitrate contamination, groundwater samples were collected monthly for 3 years (1997–1999) from 12 wells in rural areas with different land-use activities and analyzed for the concentrations and N isotopic ratios (δ 15 N) of nitrate. The characteristics of nitrate contamination clearly differed with land-use activities. The percentages of samples that had a nitrate concentration exceeding the national standard for drinking water (10 mg N L −1 ) were 0, 23, 43, and 67% for the uncontaminated natural area, cropping area, cropping-livestock farming complex area, and residential area, respectively. The range of δ 15 N values was between +1.4 and +4.5‰ for groundwater nitrate from the uncontaminated natural area. In the cropping area, the δ 15 N values were slightly different with the type of fertilizer applied to fields in the vicinity of the well, and the values ranged between +8.7 and +14.4‰ for the compost-applied area and between +4.5 and +8.5‰ for the area where urea was applied with compost. The δ 15 N values of the cropping-livestock farming complex area ranged from +1.0 to +17.7‰, probably resulting from mixed contamination sources (inorganic fertilizer and livestock manure). The well located closest to the livestock feedlot had relatively higher δ 15 N values, with a range between +8.7 and +17.6‰. In the residential area, a higher δ 15 N (most frequently above +10‰) of nitrate suggested that the major source of contamination was effluent from leaky septic tanks. Our data showed that unconfined groundwater is susceptible to land-use activities above the aquifers, and the impacts of the activities could be more precisely inferred from long-term data on the concentration and δ 15 N of nitrate. By determining the impacts, more effective (specific to contamination sources) measures for preventing groundwater quality could be implemented.

Electrical conductivity of saturated soil extracts (ECe) in three reclaimed tideland (RTL) soils on the west coast of Korea decreased with time since reclamation, indicating natural desalinization through leaching of salts by precipitation water. Soil N concentration increased with decreasing ECe. With the increase in soil N concentration, the δ15N decreased, likely caused by the input of 15N-depleted N sources. As N2-fixing plant species were found in the oldest RTL, atmospheric N2 fixation likely contributed to the increase in soil N concentration in the oldest RTL. Negative δ15N (−7.1 to −2.0‰) of total inorganic N (NH4 ++NO3 −) and published data on N deposition near the study area indicate that atmospheric N deposition might be another source of N in the RTLs. Meanwhile, the consistently negative δ15N of soil NO3 − excluded N input from chemical fertilizer through groundwater flow as a potential N source, since NO3 − in groundwater generally have a positive δ15N. The patterns of δ15N of NH4 + (+2.3 to +5.1‰) and NO3 − (−9.2 to −5.0‰) suggested that nitrification was an active process that caused 15N enrichment in NH4 + but denitrification was probably minimal which would otherwise have caused 15N enrichment in NO3 −. A quantitative approach on N budget would provide a better understanding of soil N dynamics in the studied RTLs.

The transport of P sources (organic and inorganic phosphorus) using electrokinetic process through a low-permeability soils was investigated. A series of batch experiments was conducted to construct the adsorption isotherms of KH2PO4 and triethyl phosphate (TEP) on kaolin soils. Approximately 60.3% of phosphorus from KH2PO4 was adsorbed within 24 hours, and the maximum adsorption (73%) was attained at 6 days after adsorption. In contrast, TEP showed no P adsorption in 7 days, thus suggesting an alternative P source that may maintain a favorable proportion of C∶N∶P through the effective delivery duringin situ bioremediation in low permeability soils. Experiments using electrokinetic process were carried out with electrokinetic reactor having a hydraulic conductivity of 1.99×10−7 cm s−1 for a 0.01 M NaCl aqueous solution. TEP and KH2PO4 were used as organic P source and inorganic P source, respectively, and introduced individually into a chamber near the platinum anode and near the platinum cathode, respectively. Potassium dihydrogen phosphate was not distributed uniformly along the soil column and most of transported phosphorus was changed to water-insoluble aluminum phosphate after 12 days of treatment, indicating the decrease of bioavailability of the phosphorus. In case of TEP, the advancing P front progressed with time, resulting in uniform P distribution through the kaolin column. In terms of transport, organic phosphorus, TEP, would be a more effective P source than inorganic phosphorus, KH2PO4, in electrokinetic enhanced bioremediation.

Natural abundances of carbon-13 and nitrogen-15 were analyzed in 3-year bands of annual rings of three red pine (Pinus densiflora Sieb. et Zucc.) trees in eastern Korea to elucidate their variations in relation to changing environmental conditions, particularly air pollution. Tree ring width had a trend to decrease with time (r = −0.79, P < 0.001); however, tree-ring indices did not show any consistent pattern of change over time. Tree ring indices were correlated neither with the respective precipitation nor temperature. The δ13C (range: −25.7 to −24.4a) of tree rings became less negative as tree ring indices increase (r = 0.43, P < 0.05), suggesting that radial growth of trees might have been affected by environmental factors such as nutrient deficiency and acid rain that affect carboxylation efficiency. Increasing N concentration (range: 0.40 to 0.68 g N kg−1) with decreasing δ15N (range: +4.2 to −0.6a) of tree rings (r = −0.84, P < 0.01) during the period (since 1980s) of increasing NO x emission in Korea was consistent with the hypothesis that increasing deposition of N depleted in 15N may lead to 15N depletion in tree tissues. However, quantitative information on inter-ring translocation of N which may cause N isotopic fractionation is necessary to use the δ15N signal as a reliable indicator of air pollution.

This study was conducted to examine whether the applications of N-inputs (compost and fertilizer) having different N isotopic compositions (δ15N) produce isotopically different inorganic-N and to investigate the effect of soil moisture regimes on the temporal variations in the δ15N of inorganic-N in soils. To do so, the temporal variations in the concentrations and the δ15N of NH4+ and NO3− in soils treated with two levels (0 and 150 mg N kg−1) of ammonium sulfate (δ15N=−2.3‰) and compost (+13.9‰) during a 10-week incubation were compared by changing soil moisture regime after 6 weeks either from saturated to unsaturated conditions or vice versa. Another incubation study using 15N-labeled ammonium sulfate (3.05 15N atom%) was conducted to estimate the rates of nitrification and denitrification with a numerical model FLUAZ. The δ15N values of NH4+ and NO3− were greatly affected by the availability of substrate for each of the nitrification and denitrification processes and the soil moisture status that affects the relative predominance between the two processes. Under saturated conditions for 6 weeks, the δ15N of NH4+ in soils treated with fertilizer progressively increased from +2.9‰ at 0.5 week to +18.9‰ at 6 weeks due to nitrification. During the same period, NO3− concentrations were consistently low and the corresponding δ15N increased from +16.3 to +39.2‰ through denitrification. Under subsequent water-unsaturated conditions, the NO3− concentrations increased through nitrification, which resulted in the decrease in the δ15N of NO3−. In soils, which were unsaturated for the first 6-weeks incubation, the δ15N of NH4+ increased sharply at 0.5 week due to fast nitrification. On the other hand, the δ15N of NO3− showed the lowest value at 0.5 week due to incomplete nitrification, but after a subsequence increase, they remained stable while nitrification and denitrification were negligible between 1 and 6 weeks. Changing to saturated conditions after the initial 6-weeks incubation, however, increased the δ15N of NO3− progressively with a concurrent decrease in NO3− concentration through denitrification. The differences in δ15N of NO−3 between compost and fertilizer treatments were consistent throughout the incubation period. The δ15N of NO3− increased with the addition of compost (range: +13.0 to +35.4‰), but decreased with the addition of fertilizer (−10.8 to +11.4‰), thus resulting in intermediate values in soils receiving both fertilizer and compost (−3.5 to +20.3‰). Therefore, such differences in δ15N of NO3− observed in this study suggest a possibility that the δ15N of upland-grown plants receiving compost would be higher than those treated with fertilizer because NO3− is the most abundant N for plant uptake in upland soils.

This study was performed to establish standard methods and media for detecting S. Enteritidis in Korean style foods. For the preliminary experiment, the enrichment procedures for the recovery of acid or heat injured S. Enteritidis was compared. In the mixed culture system, Salmonella Enteritidis ATCC 13076, Shigella sonnei ATCC 9290, Staphylococcus aureus ATCC 25923, Listeria monocytogenes ATCC 19111, Escherichia coli ATCC 25922 were used. S. Enteritidis in food system were evaluated by using 5 different preenrichment media (TSB: Tryptic Soy Broth, LB: Lactose Broth, BPW: Buffered Peptone Water, SB: Selenite Broth, SCB: Selenite Cystine Broth) and 2 different enrichment media (TT: Tetrathionate Broth, RV: Rappaport and Vassiliadis). TSB was the most effective medium to detect acid and heat injured S. Enteritidis after 6 h incubation, but SB and SCB were also effective after 24 h incubation. For the recovery of heat injured S. Enteritidis at 65C, 5 pre-enrichment media did not show significant differences (P

Effects of nitrogen addition on the growth of Indigofera pseudo-tinctoria (Leguminosae) in the waste landfill site was investigated. Nitrogen fertilization in the nitrogen poor soils of waste landfill may influence the growth of nitrogen fixing plants beneficially or detrimentally. When I. pseudo-tinctoria was fertilized with three different levels of nitrogen, the coverage of plants treated with 46 g N/ and 460 g N/ was significantly less than that of plants treated with 23 g N/. The growth rates of plant height treated with 46 g N/ and 460 g N/ were significantly less than those of plants treated with 23 g N/. The growth rates of plant diameter treated with 46 g N/ and 460 g N/ were significantly less than those of plants treated with 23 g N/. Dry weights of whole plants in control sites were higher than those of all the others nitrogen treatment sites. Nodule numbers were higher in control plants than those of plants in all the other nitrogen treatment sites. It is suggested that nitrogen fertilizer addition over 23 g N/ affect the growth of some nitrogen fixing plants, such as I. pseudo-tinctoria, negatively.

Nitrate contamination in the aquatic systems is the primary indicator of poor agricultural management. The influence of sewage sludge application rates (0, 10, 25, 50 and 100 dry Mg/ha) on distribution of nitrate originating from the sewage sludge in soil profiles was investigated. Soil profile monitoring of nitrate was carried out with a Lakeland clay soil in 1997. Irrespectively of the sewage sludge application rates up to 50 dry Mg/ha, the concentration of -N at the 120 cm depth was below 10 mg/kg and the difference due to the amount of sewage sludge application was negligible at this depth. There was virtually no -N below 120 cm depth and this was confirmed by a deep sampling up to 300 cm depth. Most of the nitrate remained in the surface 60 cm of the soil. Below 120 cm depth nitrate concentration was very low because of the denitrification even at high sewage sludge rate of 100 dry Mg/ha. The -N concentrations in the soil fluctuated over the growing season due to plant uptake and denitrification. The risk of groundwater contamination by nitrate from sewage sludge application up to high rate of 100 dry Mg/ha was very low in a wheat grown clay soil with high water table (

It has been accepted that variations in stable N isotope ratios (15N/14N) can potentially provide useful, sometimes unique, information on the sources of nitrate in groundwater, because N isotope compositions are generally different among various N pools such as atmospheric N2, soil, chemical fertilizer, and manure. However, this review strongly suggests that interpretation of the nitrate source based on a single measurement of δ15N may not be accurate because the isotopic composition of groundwater nitrate is a function of its source and any isotope fractionation that may occur during its generation or transport to groundwater. This review, therefore, shows that to evaluate the nitrate contamination source using δ15N technique, it is more reasonable to use correlation between the concentrations and δ15N of NO3 −. For example, a positive correlation indicates15N-enriched source such as manure, while15N-depleted source results in a negative correlation. The correlation analysis can also be used in evaluation of denitrification and nitrification. Denitrification is a key process affecting δ15N of NO3 −, i.e. if significant amount of nitrate is removed through denitrification, it is not easy to discriminate fertilizer-derived nitrate from manure-or compost-derived one because denitrification increase the δ15N of the remaining NO3 −. Therefore, it is important to assess whether denitrification may be occurring or not when evaluating isotope data on nitrate. By using dual (δ15N air and δ18O vsmow ) isotopic indicators, denitrification can be evaluated more accurately.

To evaluate the nitrate contamination sources of unconfined groundwater in the North Han River basin (127°45′E, 37°55′N), groundwater samples were collected monthly for three years (1997–1999) from 20 wells, and analyzed for the concentration (n=599) and δ15N (n=96) of NO3−N. Frequency distribution of NO3−N concentration showed that 43.9% of samples exceeded the national standard for drinking water (10 mg NO3−N L−1). During dry season between October and March, only 36.1% of a total of 296 samples had NO3−N concentration above 10 mg L−1. However, 51.5% of a total of 303 samples exceeded the standard level during wet season between April and September. Concentrations of nitrate increased with direction of groundwater flow. Wells located in vicinity of livestock feedlots showed consistently high nitrate concentration irrespective of precipitation pattern. The δ15N signatures of NO3− showed that in general, both15N-depleted source (e.g., chemical fertilizer) and15N-enriched source (e.g., compost and manure) impacted groundwater quality concurrently. The δ15N ranges of groundwater NO3− were +1.5–+12.9‰ in dry season and +3.2–+9.9‰ in wet season. These δ15N data suggested that the effects of compost and/or manure on nitrate concentration were apparent in dry season. A positive correlation (r2=0.32) between N concentration and δ15N of NO3− in dry season also suggested that nitrate concentration increased with increasing loading of nitrate from compost and/or manure wastewater. On the other hand, the relatively narrow range of δ15N and high nitrate concentration in wet season suggested that increased flush of nitrate derived from mixed sources such as fertilizer, compost, and manure during storm event resulted in high nitrate concentration. In this area, neither high δ15N values nor a negative correlation between δ15N and N concentration of NO3−, indicating denitrification was observed because of the coarse textured soil matrix. Therefore, reduction of nitrogen inputs through curtailment of fertilizer and compost application rates and appropriate treatment of livestock manure are the most effective and practical ways to prevent groundwater contamination.

To investigate the effect of inorganic fertilizer and composted manure amendments on the N isotope composition (delta15N) of crop and soil, maize (Zea mays L.) was cultivated under greenhouse conditions for 30, 40, 50, 60, and 70 days. Composted pig manure (delta15N= +13.9‰) and urea (-2.3‰) were applied at 0 and 0 kg N ha−1 (C0U0), 0 and 150 kg N ha−1 (C0U2), 150 and 0 kg N ha−1 (C2U0), and 75 and 75 kg N ha−1 (C1U1), respectively. The delta15N of total soil-N was not affected by both amendments, but delta15N of NH+4 and NO−3 provided some information on the N isotope fractionation in soil. During the early growth stage, significant differences (P < 0.05) in delta15N among maize subjected to different treatments were observed. After 30 days of growth, the delta15N values of maize were +6.6‰ for C0U0, +1.1‰ for C0U2, +7.7‰ for C2U0, and +4.5‰ for C1U1. However, effects of urea and composted manure application on maize delta15N progressively decreased with increasing growth period, probably due to isotope fractionation accompanying N losses and increased uptake of soil-derived N by maize. After 70 days of growth, delta15N of leaves and grains of maize amended with composted pig manure were significantly (P < 0.05) higher than those with urea. The temporal variations in delta15N of maize amended with urea and composted manure indicate that plant delta15N is generally not a good tracer for N sources applied to field. Our data can be used in validation of delta15N fractionation models in relation to N source inputs.

A pot experiment was conducted to study the effect of combined application of composted pig manure and urea on the availability of urea for corn (Zea mays L.). Corn was cultivated for 30 and 60 days. 15N-Labeled urea (6.17 15N atom %) was added to soil at 0, 37.5, 75 and 150 kg N ha−1, and unlabeled compost (0.37 15N atom %) was added at 0 and 150 kg N ha−1. After 30-days growth, the uptake efficiencies of applied N by corn were 51.6 and 55.8%, for the treatments of 75 kg urea and 150 kg compost-N ha−1, respectively. However, the efficiencies decreased to 32.5% for urea-N and 31.6% for compost-N under the mixed treatment of both N inputs at the rate of 75 kg urea and 150 kg compost-N ha−1, due to the competition of N for corn uptake. After 60-days growth, the urea-N efficiencies were 38.7, 46.8 and 49.6% for the treatments receiving urea at 37.5, 75 and 150 kg N ha−1, they then decreased to 32.9, 39.3 and 39.7%, respectively, by the combined application of 150 kg compost-N ha−1. However, the efficiency of compost-N was about 60% irrespective of urea-N addition. The urea-N uptake efficiency, measured using non-isotopic regression technique, was slightly higher by about 10% than the isotopic technique, an indication of `pool substitution'. However, a large increase in corn uptake of soil-N or compost-N was not observed. After a 60-day growth period, the percentages of applied urea-N which was immobilized in the soil in 2 M KCl non-extractable form were 13.6∼21.7% for treatments without compost and 32.8∼41.2% with compost. These results suggested that the high immobilization of urea-N in soils through the combined application of compost compared to treatments without compost was responsible for the lower uptake efficiency of urea-N by corn.

Herpes zoster represents the reactivation of latent varicella-zoster virus located in the dorsal root ganglion. The virus multiplies and migrates to the skin surface producing a characteristic, usually painful, pustular eruption. Severe pain during the acute phase of herpes zoster has been associated with a higher risk of developing postherpetic neuralgia. Sympathetic ganglion block and somatic nerve block have been used for patients in the acute phase of herpes zoster to alleviate pain and prevent postherpetic neuralgia. Sympathetic nerve block appears to achieve these goals by blocking the profound sympathetic stimulation that is a result of the viral inflammation of the nerve and ganglion. However, they require repeated local anesthetic injections to relieve the symptoms of acute herpes zoster as well as to prevent the occurrence of postherpetic neuralgia. Pulsed radiofrequency has been proposed as safe, nondestructive treatment method. We present a case of acute herpes zoster that was managed with pulsed radiofrequency treatment. The results were satisfactory. (Korean J Anesthesiol 2007; 52: 586~90)

Ankylosing spondylitis is a chronic and systemic disease invloving the axial skeleton. In patient with involved cervical spine of the ankylosing spondylitis, endotracheal intubation by direct laryngoscope may be difficult or impossible because they have a limitation of cervical movement and anatomical anomalies. Additionally, ossification of the interspinous ligaments and the formation of bony bridges (syndesmophytes) between vertebrae, resulting in a classic “bamboo spine” appearance make difficult or impossible placement of an epidural or spinal needle. We report a case of a patient with long standing ankylosing spondylitis who underwent revision arthroplasty of the hip using combined continuous psoas compartment block and sciatic nerve block.