• Title/Summary/Keyword: Dry periods

Search Result 498, Processing Time 0.037 seconds

Growth Performances and Physiological Responses of Quercus spp. and Fraxinus rhynchophylla Subjected to Different Soil Moisture Regimes and Nutrition Levels (수분(水分) 및 양료(養料) 처리(處理)에 따른 참나무류와 물푸레나무의 생장 및 생리 반응)

  • Kwon, Ki Won;Lee, Jeoung Ho
    • Journal of Korean Society of Forest Science
    • /
    • v.83 no.2
    • /
    • pp.164-174
    • /
    • 1994
  • Temporal changes in growth performances, chlorophyll contents, and tissue water relations for determining their physiological responses of five economic tree species subjected to chronic water and nutrition stresses were investigated with containerized seedlings grown in different soil moisture regimes and nutrition levels. Seedlings of Quercus acutissima, Q. variabilis, Q. mongolica, Q. serrata, and Fraxinus rhynchophylla were propagated in plastic pots(I.D. $16cm{\times}Depth$ 16cm) for the experiments. The seedlings were subjected to two soil moisture regimes of dry and wet soils and two nutrition levels of fertilization with N+P+K and no fertilization through the growing season from May to September in a green house. For the purpose of analyzing their responses to the environmental stresses, seedling heights and root collar diameters, chlorophyll contents, and P-V curve parameters of the seedlings were measured in May, July, and September. The environmental stresses coming from moisture and nutrient deficits affected the growth performances of seedlings variously among species and among different growing periods, as well as between height and basal diameter growth of seedlings. The growth performances of Q. acutissima were influenced sensitively on the stresses, but those of Q. mongolica less influenced in comparison with other species. Chlorophyll contents were generally higher in Quercus spp. than F. rhynchophylla through the growing season. The chlorophyll contents changed by species and by treatment through the season within ranges of 0.14~1.96 mg/g dry wt. of chlorophyll a and within 0.16~1.79mg/g dry wt. of chlorophyll b, respectively. But the contents seemed to be decreased gradually through the chronic environmental stresses and leaf senescence. The osmotic potential at full turgor(${\Psi}{{\pi}o}$) and turgor loss point(${\Psi}{\pi}p$) had temporarily declined up to 3 to 5bars from -7.0~-12.4bars in May to -10.2~-17.5bars in September and up to 5 to 6bars from -7.6~-14.2bars in May to -12.9~-20.4bars in September, respectively, with some exceptions. The values of ${\Psi}{\pi}p$ were generally high in F. rhynchophylla in May and July, but high in Q. serrata in September. Relative water contents at turgor loss point(RWCp) were generally high in F. rhynchophylla, but the temporal changes of RWCp were quite and frequently different among species and among treatment.

  • PDF

Analysis of extreme cases of climate change impact on watershed hydrology and flow duration in Geum river basin using SWAT and STARDEX (SWAT과 STARDEX를 이용한 극한 기후변화 사상에 따른 금강유역의 수문 및 유황분석)

  • Kim, Yong Won;Lee, Ji Wan;Kim, Seong Joon
    • Journal of Korea Water Resources Association
    • /
    • v.51 no.10
    • /
    • pp.905-916
    • /
    • 2018
  • The purpose of this study is to evaluate the climate change impact on watershed hydrology and flow duration in Geum River basin ($9,645.5km^2$) especially by extreme scenarios. The rainfall related extreme index, STARDEX (STAtistical and Regional dynamical Downscaling of EXtremes) was adopted to select the future extreme scenario from the 10 GCMs with RCP 8.5 scenarios by four projection periods (Historical: 1975~2005, 2020s: 2011~2040, 2050s: 2041~2070, 2080s: 2071~2100). As a result, the 5 scenarios of wet (CESM1-BGC and HadGEM2-ES), normal (MPI-ESM-MR), and dry (INM-CM4 and FGOALS-s2) were selected and applied to SWAT (Soil and Water Assessment Tool) hydrological model. The wet scenarios showed big differences comparing with the normal scenario in 2080s period. The 2080s evapotranspiration (ET) of wet scenarios varied from -3.2 to +3.1 mm, the 2080s total runoff (TR) varied from +5.5 to +128.4 mm. The dry scenarios showed big differences comparing with the normal scenario in 2020s period. The 2020s ET for dry scenarios varied from -16.8 to -13.3 mm and the TR varied from -264.0 to -132.3 mm respectively. For the flow duration change, the CFR (coefficient of flow regime, Q10/Q355) was altered from +4.2 to +10.5 for 2080s wet scenarios and from +1.7 to +2.6 for 2020s dry scenarios. As a result of the flow duration analysis according to the change of the hydrological factors of the Geum River basin applying the extreme climate change scenario, INM-CM4 showed suitable scenario to show extreme dry condition and FGOALS-s2 showed suitable scenario for the analysis of the drought condition with large flow duration variability. HadGEM2-ES was evaluated as a scenario that can be used for maximum flow analysis because the flow duration variability was small and CESM1-BGC was evaluated as a scenario that can be applied to the case of extreme flood analysis with large flow duration variability.

Studies on Relations between Various Coeffcients of Evapo-Transpiration and Quantities of Dry Matters for Tall-and Short Statured Varieties of Paddy Rice (논벼 장.단간품종의 증발산제계수와 건물량과의 관계에 대한 연구(I))

  • 류한열;김철기
    • Magazine of the Korean Society of Agricultural Engineers
    • /
    • v.16 no.2
    • /
    • pp.3361-3394
    • /
    • 1974
  • The purpose of this thesis is to disclose some characteristics of water consumption in relation to the quantities of dry matters through the growing period for two statured varieties of paddy rice which are a tall statured variety and a short one, including the water consumption during seedling period, and to find out the various coefficients of evapotranspiration that are applicable for the water use of an expected yield of the two varieties. PAL-TAL, a tall statured variety, and TONG-lL, a short statured variety were chosen for this investigation. Experiments were performed in two consecutive periods, a seedling period and a paddy field period, In the investigation of seedling period, rectangular galvanized iron evapotranspirometers (91cm${\times}$85cm${\times}$65cm) were set up in a way of two levels (PAL-TAL and TONG-lL varieties) with two replications. A standard fertilization method was applied to all plots. In the experiment of paddy field period, evapotanspiration and evaporation were measured separately. For PAL-TAL variety, the evapotranspiration measurements of 43 plots of rectangular galvanized iron evapotranspirometer (91cm${\times}$85cm${\times}$65cm) and the evaporation measurements of 25 plots of rectangular galvanized iron evaporimeter (91cm${\times}$85cm${\times}$15cm) have been taken for seven years (1966 through 1972), and for TONG-IL variety, the evapotranspiration measurements of 19 plots and the evaporation measurements of 12 plots have been collected for two years (1971 through 1972) with five different fertilization levels. The results obtained from this investigation are summarized as follows: 1. Seedling period 1) The pan evaporation and evapotranspiration during seedling period were proved to have a highly significant correlation to solar radiation, sun shine hours and relative humidity. But they had no significant correlation to average temperature, wind velocity and atmospheric pressure, and were appeared to be negatively correlative to average temperature and wind velocity, and positively correlative to the atmospheric pressure, in a certain period. There was the highest significant correlation between the evapotranspiration and the pan evaporation, beyond all other meteorological factors considered. 2) The evapotranpiration and its coefficient for PAL-TAL variety were 194.5mm and 0.94∼1.21(1.05 in average) respectively, while those for TONG-lL variety were 182.8mm and 0.90∼1.10(0.99 in average) respectively. This indicates that the evapotranspiration for TONG-IL variety was 6.2% less than that for PAL-TAL variety during a seedling period. 3) The evapotranspiration ratio (the ratio of the evapotranspiration to the weight of dry matters) during the seedling period was 599 in average for PAL-TAL variety and 643 for TONG-IL variety. Therefore the ratio for TONG-IL was larger by 44 than that for PAL-TAL variety. 4) The K-values of Blaney and Criddle formula for PAL-TAL variety were 0.78∼1.06 (0.92 in average) and for TONG-lL variety 0.75∼0.97 (0.86 in average). 5) The evapotranspiration coefficient and the K-value of B1aney and Criddle formular for both PAL-TAL and TONG-lL varieties showed a tendency to be increasing, but the evapotranspiration ratio decreasing, with the increase in the weight of dry matters. 2. Paddy field period 1) Correlation between the pan evaporation and the meteorological factors and that between the evapotranspiration and the meteorological factors during paddy field period were almost same as that in case of the seedling period (Ref. to table IV-4 and table IV-5). 2) The plant height, in the same level of the weight of dry matters, for PAL-TAL variety was much larger than that for TONG-IL variety, and also the number of tillers per hill for PAL-TAL variety showed a trend to be larger than that for TONG-IL variety from about 40 days after transplanting. 3) Although there was a tendency that peak of leaf-area-index for TONG-IL variety was a little retarded than that for PAL-TAL variety, it appeared about 60∼80 days after transplanting. The peaks of the evapotranspiration coefficient and the weight of dry matters at each growth stage were overlapped at about the same time and especially in the later stage of growth, the leaf-area-index, the evapotranspiration coefficient and the weight of dry matters for TONG-IL variety showed a tendency to be larger then those for PAL-TAL variety. 4) The evaporation coefficient at each growth stage for TONG-IL and PAL-TALvarieties was decreased and increased with the increase and decrease in the leaf-area-index, and the evaporation coefficient of TONG-IL variety had a little larger value than that of PAL-TAL variety. 5) Meteorological factors (especially pan evaporation) had a considerable influence to the evapotranspiration, the evaporation and the transpiration. Under the same meteorological conditions, the evapotranspiration (ET) showed a increasing logarithmic function of the weight of dry matters (x), while the evaporation (EV) a decreasing logarithmic function of the weight of dry matters; 800kg/10a x 2000kg/10a, ET=al+bl logl0x (bl>0) EV=a2+b2 log10x (a2>0 b2<0) At the base of the weight of total dry matters, the evapotranspiration and the evaporation for TONG-IL variety were larger as much as 0.3∼2.5% and 7.5∼8.3% respectively than those of PAL-TAL variety, while the transpiration for PAL-TAL variety was larger as much as 1.9∼2.4% than that for TONG-IL variety on the contrary. At the base of the weight of rough rices the evapotranspiration and the transpiration for TONG-IL variety were less as much as 3.5% and 8.l∼16.9% respectively than those for PAL-TAL variety and the evaporation for TONG-IL was much larger by 11.6∼14.8% than that for PAL-TAL variety. 6) The evapotranspiration coefficient, the evaporation coefficient and the transpiration coefficient and the transpiration coefficient were affected by the weight of dry matters much more than by the meteorological conditions. The evapotranspiratioa coefficient (ETC) and the evaporation coefficient (EVC) can be related to the weight of dry matters (x) by the following equations: 800kg/10a x 2000kg/10a, ETC=a3+b3 logl0x (b3>0) EVC=a4+b4 log10x (a4>0, b4>0) At the base of the weights of dry matters, 800kg/10a∼2000kg/10a, the evapotranspiration coefficients for TONG-IL variety were 0.968∼1.474 and those for PAL-TAL variety, 0.939∼1.470, the evaporation coefficients for TONG-IL variety were 0.504∼0.331 and those for PAL-TAL variety, 0.469∼0.308, and the transpiration coefficients for TONG-IL variety were 0.464∼1.143 and those for PAL-TAL variety, 0.470∼1.162. 7) The evapotranspiration ratio, the evaporation ratio (the ratio of the evaporation to the weight of dry matters) and the transpiration ratio were highly affected by the meteorological conditions. And under the same meteorological condition, both the evapotranspiration ratio (ETR) and the evaporation ratio (EVR) showed to be a decreasing logarithmic function of the weight of dry matters (x) as follows: 800kg/10a x 2000kg/10a, ETR=a5+b5 logl0x (a5>0, b5<0) EVR=a6+b6 log10x (a6>0 b6<0) In comparison between TONG-IL and PAL-TAL varieties, at the base of the pan evaporation of 343mm and the weight of dry matters of 800∼2000kg/10a, the evapotranspiration ratios for TONG-IL variety were 413∼247, while those for PAL-TAL variety, 404∼250, the evaporation ratios for TONG-IL variety were 197∼38 while those for PAL-TAL variety, 182∼34, and the transpiration ratios for TONG-IL variety were 216∼209 while those for PAL-TAL variety, 222∼216 (Ref. to table IV-23, table IV-25 and table IV-26) 8) The accumulative values of evapotranspiration intensity and transpiration intensity for both PAL-TAL and TONG-IL varieties were almost constant in every climatic year without the affection of the weight of dry matters. Furthermore the evapotranspiration intensity appeared to have more stable at each growth stage. The peaks of the evapotranspiration intensity and transpiration intensity, for both TONG-IL and PAL-TAL varieties, appeared about 60∼70 days after transplanting, and the peak value of the former was 128.8${\pm}$0.7, for TONG-IL variety while that for PAL-TAL variety, 122.8${\pm}$0.3, and the peak value of the latter was 152.2${\pm}$1.0 for TONG-IL variety while that for PAL-TAL variety, 152.7${\pm}$1.9 (Ref.to table IV-27 and table IV-28) 9) The K-value in Blaney & Criddle formula was changed considerably by the meteorological condition (pan evaporation) and related to be a increasing logarithmic function of the weight of dry matters (x) for both PAL-TAL and TONG-L varieties as follows; 800kg/10a x 2000kg/10a, K=a7+b7 logl0x (b7>0) The K-value for TONG-IL variety was a little larger than that for PAL-TAL variety. 10) The peak values of the evapotranspiration coefficient and k-value at each growth stage for both TONG-IL and PAL-TAL varieties showed up about 60∼70 days after transplanting. The peak values of the former at the base of the weights of total dry matters, 800∼2000kg/10a, were 1.14∼1.82 for TONG-IL variety and 1.12∼1.80, for PAL-TAL variety, and at the base of the weights of rough rices, 400∼1000 kg/10a, were 1.11∼1.79 for TONG-IL variety and 1.17∼1.85 for PAL-TAL variety. The peak values of the latter, at the base of the weights of total dry matters, 800∼2000kg/10a, were 0.83∼1.39 for TONG-IL variety and 0.86∼1.36 for PAL-TAL variety and at the base of the weights of rough rices, 400∼1000kg/10a, 0.85∼1.38 for TONG-IL variety and 0.87∼1.40 for PAL-TAL variety (Ref. to table IV-18 and table IV-32) 11) The reasonable and practicable methods that are applicable for calculating the evapotranspiration of paddy rice in our country are to be followed the following priority a) Using the evapotranspiration coefficients based on an expected yield (Ref. to table IV-13 and table IV-18 or Fig. IV-13). b) Making use of the combination method of seasonal evapotranspiration coefficient and evapotranspiration intensity (Ref. to table IV-13 and table IV-27) c) Adopting the combination method of evapotranspiration ratio and evapotranspiration intensity, under the conditions of paddy field having a higher level of expected yield (Ref. to table IV-23 and table IV-27). d) Applying the k-values calculated by Blaney-Criddle formula. only within the limits of the drought year having the pan evaporation of about 450mm during paddy field period as the design year (Ref. to table IV-32 or Fig. IV-22).

  • PDF

Geochemistry of Total Gaseous Mercury in Nan-Ji-Do, Seoul, Korea (난지도 지역의 대기수은 지화학)

  • Kim, Min-Young;Lee, Gang-Woong;Shin, Jae-Young;Kim, Ki-Hyun
    • Journal of the Korean earth science society
    • /
    • v.21 no.5
    • /
    • pp.611-622
    • /
    • 2000
  • To investigate the exchange rates of mercury(Hg) across soil-air boundary, we undertook the measurements of Hg flux using gradient technique from a major waste reclamation site, Nan-Ji-Do. Based on these measurement data, we attempted to provide insights into various aspects of Hg exchange in a strongly polluted soil environment. According to our analysis, the study site turned out to be not only a major emission source area but also a major sink area. When these data were compared on hourly basis over a full day scale, large fluxes of emission and deposition centered on daytime periods relative to nighttime periods. However, when comparison of frequency with which emission or deposition occurs was made, there emerged a very contrasting pattern. While emission was dominant during nighttime periods, deposition was most favored during daytime periods. When similar comparison was made as a function of wind direction, it was noticed that there may be a major Hg source at easterly direction to bring out significant deposition of Hg in the study area. To account for the environmental conditions controlling the vertical direction of Hg exchange, we compared environmental conditions for both the whole data group and those observed from the wind direction of strong deposition events. Results of this analysis indicated that the concentrations of pollutant species varied sensitively enough to reflect the environmental conditions for each direction of exchange. When correlation analysis was applied to our data, results indicated that windspeed and ozone concentrations best reflected changes in the magnitudes of emission/deposition fluxes. The results of factor analysis also indicated the possibility that Hg emission of study area is temperature-driven process, while that of deposition is affected by a mixed effects of various factors including temperature, ozone, and non-methane HCs. If the computed emission rate is extrapolated to the whole study area we estimate that annual emission of Hg from the study area can amount to approximately 6kg.

  • PDF

Effects of high energy diet on growth performance, carcass characteristics, and blood constituents of final fattening Hanwoo steers (고에너지 사양이 비육후기 거세한우의 성장, 도체, 및 혈액성상에 미치는 영향)

  • Chung, Ki Yong;Chang, Sun Sik;Lee, Eun Mi;Kim, Hyun Ju;Park, Bo Hye;Kwon, Eung Gi
    • Korean Journal of Agricultural Science
    • /
    • v.42 no.3
    • /
    • pp.261-268
    • /
    • 2015
  • The aim of this study was to examine the effects of high energy diet on growth 26mon, 28mon, and 30mon in Hanwoo at different ages. High energy diet required not only an amount of concentrate on days of fattening periods but also induced cost for the management. We hypothesized that high energy diet was able to reduce a fattening period to reach a certain quality grade. A $2{\times}3$ factorial arrangement (High energy, control vs 26, 28, 30month endpoints) in a completely random design was used to feed 48 Hanwoo steers. Four steers were fed in same pen and 12 pens were used for treatment. Blood was drawn from each steers on every other months during early, middle, and final fattening periods. Over all ADG and feed efficiency were not different between high energy and control diet (P > 0.05). Dry matter intake was induced 30 mo-old early and final fattening periods at high energy diet. Serum glucose concentration were increased (P < 0.05) at 30 and 26month old steers. Marbling scores were greater at 30 month old than 26 and 28 month old Hanwoo steers. Carcass weight of Hanwoo steers were greater at 30 mon-old groups than other groups. These result indicated that high energy diet (+3% TDN) and slaughter endpoint collectively contribute to the observed quality grade compositional differences among three final fattening periods of Hanwoo steers.

Distribution of Larval Fishes off the East Sea, Korea (동해 근해에 출현하는 어류 자치어 분포 특성)

  • Choi, Hee Chan;Jung, Hae Kun;Cho, Jeong Hyun;Youn, Seok Hyun;Oh, Hyun Ju
    • Korean Journal of Ichthyology
    • /
    • v.34 no.3
    • /
    • pp.186-200
    • /
    • 2022
  • In order to understand the species composition and distribution characteristics of larval assemblages in the East Sea, Korea, larvae were collected at 13 stations every other month from February to December 2018. Fish larvae were identified through DNA barcoding along with morphological methods, and as the result, a total of 104 taxonomic groups appeared during the survey. Among these, Engraulis japonicus, which accounted for 76.2% of the total population, was the most dominant species, followed by Maurolicus japonicus, which accounted for 15.0%. In addition, Ammodytes personatus, Champsodon snyderi, Scomber japonicus and Echelus uropterus appeared more frequently than other taxa. The above six species accounted for 93.2% of the total catch. The number of taxa and the amount of larvae collected in the survey area were higher during the high water temperature periods (June to October) than during the low water temperature periods (February, April and December). Analysis of similarity (ANOSIM) showed a statistically significant difference in monthly larval assemblages. The results of the canonical correspondence analysis (CCA) show that the distributions of larval community were mainly affected by sea surface temperature during low water temperature periods, and various environmental factors such as salinity, dry weight of zooplankton, and the concentrations of nutrients during high water temperature periods.

Evaluation of Se Accumulation in the Production of Se-treated Soybean Sprouts and Mungbean Sprouts

  • Bai, Hong-Sook;Kim, Hyeong-Soo;Bai, Sung-Chul;Kim, Dae-Jin
    • Preventive Nutrition and Food Science
    • /
    • v.14 no.2
    • /
    • pp.142-147
    • /
    • 2009
  • In this study, the selenium (Se) accumulations of soybean sprouts and mungbean sprouts treated with various concentrations of Se-solutions were evaluated, as part of a broader effort to produce Se-enriched variants of the plants. Four levels of sodium selenate ($Na_{2}SeO_{4}$)-dissolved solutions (i.e. 0, T0; 6, T1; 60, T2; and $600{\mu}g/mL$, T3) were prepared and sprayed onto the plants during cultivation. The effect of different spraying periods on Se accumulation was also assessed by watering plant groups once a day for periods of one, two, or three days. Se solution remaining on the surfaces of the plants was washed out by spraying with distilled water on the final day of cultivation. However, the increase of Se accumulation in the plants was found to depend on both Se-concentration and watering period, and the soybean sprouts were determined to accumulate Se more effectively than the mungbean sprouts. Additionally, with regard to Se accumulation in the plants, the period of application of Se solution was determined to be more important than the concentration of the Se solution applied. The averaged total levels of Se-enrichment in whole soybean sprouts at T0, T1, T2, and T3 were 0.26, 65.86, 179.62, and $525.12{\mu}g/dry$ matter (DM) g, respectively, and the relative equations relating Se enrichment in soybean sprouts (Y) against watering days (X) were Y=32.505X-36.17 (T1), Y=88.46X-92.04 (T2), and Y=251.11X-254.9(T3). The averaged total levels of Se-enrichment in the whole mungbean sprouts at T1, T2, and T3 group were 0.05, 3.64, and $101.43{\mu}g/DM$ g, respectively, and the relative equations relating Se enrichment (Y) to watering days (X) for mungbean sprouts were Y=1.67X-1.3467 at T1 and Y=48.035X-46.907 at T2. The results of this study suggest that soybean sprouts and mungbean sprouts enriched with bioavailable Se can be produced on a large scale by Se supplementation, allowing for the development of healthy functional foods such as Se-enriched mungbean sprout soups and salads, Se-enriched functional drink and food additives, and selenium tablets to promote health.

Effects of Aeration Temperature and Period after BA Treatment on Growth and Lateral Root Formation of Soybean Sprouts (BA 처리 직후의 Aeration 온도와 기간이 콩나물의 생장과 세근발생에 미치는 영향)

  • 강진호;전병삼;조용준;박철종;윤수영;전승호
    • KOREAN JOURNAL OF CROP SCIENCE
    • /
    • v.49 no.3
    • /
    • pp.216-221
    • /
    • 2004
  • Treatment effect of benzyladenopurine (BA) used to block the lateral roots formed on soybean sprouts should be influenced by its applying methods. This study was done to check the effects of temperature and period from seed imbibition into 2 ppm BA solution to the first watering for sprout culture on growth and morphology of soybean sprouts. Imbibed three cultivar (cv. Pungsannamulkong, Sowonkong and Junjery) seeds for 5 houys into 2 ppm BA solution were placed under different temperatures (AT; 20, 30, $40^{\circ}$) and periods (AP; 0, 1, 2, 3, 4 hours). On the 6th day, the soybean sprouts were classified by 4 categories on the base of hypocotyl length; >7cm, 4 to 7cm), < 4cm and non-germination to calculate their composition rates, number of lateral roots, lengths of hypocotyl and root diameters at middle and hook of hypocotyl, and fraction dry weights were measured. Germination and growth responses of the cultivars were changed by AT and AP treatments. The responses, lateral root formation and fresh weights were, however, mainly affected by the cultivars used rather than Af treatment. Rate of the sprouts which formed lateral roots was decreased with increased periods to 4 hours, but their number per sprout was not different between the treatments of longer than 3 hours. Lengths of hypocotyl and root organ and total fresh weights were the highest in an hour AP treatment although longer than 3 hour AP treatments did not showed the significant difference in the lengths. Conclusionally AP treatment was more important than Af one in seed aeration for soybean sprout culture immediately after imbibition into BA solution, and was done at least for 3 hours.

Characterization of Asian dust using steric mode of sedimentation field-flow fractionation (Sd/StFFF) (Steric 모드의 침강장-흐름 분획법을 이용한 황사의 특성분석)

  • Eum, Chul Hun;Kim, Bon Kyung;Kang, Dong Young;Lee, Seungho
    • Analytical Science and Technology
    • /
    • v.25 no.6
    • /
    • pp.476-482
    • /
    • 2012
  • Asian dust particles are known to have sizes ranging from a few nanometers up to about a few micrometers. The environmental and health effects depend on the size of the dust particles. The smaller, the farther they are transported, and the deeper they penetrate into the human respiratory system. Sedimentation field-flow fractionation (SdFFF) provides separation of nano to microparticles using a combination of centrifugal force and parabolic laminar flow in a channel. In this study, the steric mode of SdFFF (Sd/StFFF) was tested for size-based separation and characterization of Asian dust particles. Various SdFFF experimental parameters including flow rate, stop-flow time and field strength of the centrifugal field were optimized for the size analysis of Asian dust. The Sd/StFFF calibration curve showed a good linearity with $R^2$ value of 0.9983, and results showed an excellent capability of Sd/StFFF for a size-based separation of micron-sized particles.The optical microscopy (OM) was also used to study the size and the shape of the dust particles. The size distributions of the samples collected during a thick dust period were shifted towards larger sizes than those of the samples collected during thin dust periods. It was also observed that size distribution of the sample collected during dry period shifts further towards larger sizes than that of the samples collected during raining period, suggesting the sizes of the dust particle decrease during raining periods as the components adsorbed on the surface of the dust particles were removed by the rain water. Results show Sd/StFFFis a useful tool for size characterization of environmental particles such as the Asian dust.

Influence of Rapeseed Meal on Growth Performance, Blood Profiles, Nutrient Digestibility and Economic Benefit of Growing-finishing Pigs

  • Choi, H.B.;Jeong, J.H.;Kim, D.H.;Lee, Y.;Kwon, H.;Kim, Y.Y.
    • Asian-Australasian Journal of Animal Sciences
    • /
    • v.28 no.9
    • /
    • pp.1345-1353
    • /
    • 2015
  • This study was conducted to investigate the influence of dietary rapeseed meal (RSM) on growth performance, blood profiles, nutrient digestibility and economic benefit of growing-finishing pigs. A total of 120 growing pigs ($[Yorkshire{\times}Landrace]{\times}Duroc$) with an initial body weight (BW) $29.94{\pm}0.06kg$ were used in this experiment. Pigs were randomly allotted into 1 of 5 treatments in a randomized complete block design and 6 replicates with 4 pigs per pen. Treatments were divided by dietary RSM supplementation levels (0%, 3%, 6%, 9%, or 12%) in growing-finishing diets. A linear decrease (p<0.05) of BW and average daily gain (ADG) were observed at 13th wk of finishing and overall periods of pigs. Additionally, gain-to-feed ratio (G/F) tended to decrease by dietary RSM supplementation in growing-finishing diets (linear, p = 0.07 and quadratic, p = 0.08). Concentrations of serum triiodothyronine and thyroxine were not influenced by dietary RSM treatments whereas thyroid gland and liver weight were increased at 13th wk of finishing period (linear, p<0.05; p<0.01) by increasing dietary RSM supplementation level. In blood profiles, serum total cholesterol and low density lipoprotein cholesterol concentrations were not differed by dietary treatments at 13th wk of finishing period whereas concentration of serum high density lipoprotein cholesterol was affected by the supplementation level of RSM, resulting in a linear RSM level responses (p<0.05). Serum blood urea nitrogen concentration tended to decrease (linear, p = 0.07; p = 0.08) at 6th wk of growing and 13th wk of finishing periods and digestibility of dry matter tended to decrease by dietary RSM (linear, p = 0.09). Crude protein, crude fat and nitrogen retention, whereas, were not affected by dietary RSM supplementation level. In the economic analysis, feed cost per weight gain was numerically decreased when RSM was provided up to 9%. Consequently, RSM could be supplemented to growing-finishing diets up to 9% ($3.07{\mu}mol/g\;Gls$) without detrimental effects on growth performance of growing-finishing pigs.