• Asian-Australasian Journal of Animal Sciences
• /
• 제5권1호
• /
• pp.81-90
• /
• 1992

Five buffaloes kept in normal ambient temperature ($30^{\circ}C$) showed no significant changes in the heart rate, respiratory rate, packed cell volume, plasma constituents and renal hemodymics during intravenous infusion of urea for 4 h. The rate of urine flow, fractional urea excretion, urinary potassium excretion and osmolar clearance significantly decreased while the renal urea reabsorption markedly increased during urea infusion. The decrease of fractional potassium excretion was concomitant with the reduction of the rate of urine flow and urine pH. In animals exposed to heat ($40^{\circ}C$) the rectal temperature heart rate and respiratory rate significantly increased while no significant changes in GFR and ERPF were observed. An intravenous infusion of urea in heat exposed animals caused the reduction of the rate of urine flow with no changes in renal urea reabsorption, urine pH and fractional electrolyte excretions. During heat exposure, there were marked increases in concentrations of total plasma protein and plasma creatinine whereas plasma inorganic phosphorus concentration significantly decreased. It is concluded that an increase in renal urea reabsorption during urea infusion in buffaloes kept in normal ambient temperature depends on the rate of urine flow which affect by an osmotic diuretic effect of electrolytes. The limitation of renal urea reabsorption in heat stressed animals would be attributed to an increases in either plasma pool size of nitrogenous substance or body metabolism.

• 한국농공학회논문집
• /
• 제57권1호
• /
• pp.89-97
• /
• 2015

This study is to assess the effect of non-point source pollution discharge loads between tillage and no-tillage applications for upland crop areas using SWAT (Soil and Water Assessment Tool) watershed modeling. For Byulmi-cheon small rural catchment ($1.17km^2$) located in upstream of Gyeongan-cheon watershed, the rainfall, discharge and stream water quality have been monitored in the catchment outlet since 2011. The SWAT model was calibrated and validated in hourly basis using 19 rainfall events during 2011-2013. The average Nash-Sutcliffe model efficiency and $R^2$ (determination coefficient) for streamflow were 0.67 and 0.79 respectively. Using the 10 % surface runoff reduction from experiment results for no-tillage condition in field plots of 3 % and 8 % slopes under sesami cultivation, the soil saturated hydraulic conductivity for upland crop areas was adjusted from 0.001 mm/hr to 0.0025 mm/hr in average. Under the condition, the catchment sediment, T-N (total nitrogen, TN), and T-P (total phosphorus, TP) discharge loads were reduced by 6.9 %, 7.4 %, and 7.7 % respectively.

• 생태와환경
• /
• 제48권2호
• /
• pp.95-107
• /
• 2015

경포호에서 수질 변수들의 장기적인 경향을 파악하기 위하여 1998년부터 2013년까지 매년 3월부터 11월까지 2개월에 1회씩 3개 지점에서 조사된 15가지 수질변수들과 강우량자료를 이용하였으며, Mann-Kendall test, Sen's slope estimator 및 linear regression을 적용 분석하였다. 계절 변화 분석에는 Mann-Kendall test 및 Sen's slope estimator만 이용하였다. 분석결과 염분, 투명도 및 영양염류 (총인, 용존무기인, 총질소, 질산성 질소, 암모니아성 질소)의 변수들만 통계학적으로 유의적인 경향을 보였다. 선형회귀 분석에서는 염분 (표층과 심층의 전 지점)과 투명도 (지점 1)만이 통계학적으로 유의적인 증가 경향을 나타냈으나, 비모수법에 의한 분석에서는 염분과 투명도 모두 전 지점에서 통계학적으로 유의적인 증가 경향을 보였다. 통계학적으로 유의적인 감소 경향을 보인 수질변수들은 선형회귀분석에서는 용존산소 (표층 지점 1, 심층 지점 2와 3), 총인(지점 1과 2), 용존무기인, 총질소, 질산성 질소 및 암모니아성 질소, 비모수법에 의한 분석에서는 용존산소 (심층 전지점), 총인, 용존무기인, 총질소, 질산성 질소 및 암모니아성 질소였다. 계절적인 경향을 분석한 결과 봄에는 염분, 탁도, 투명도 및 부유물질 (SS), 여름에는 염분, 투명도, 질산성 질소 및 부유물질, 가을에는 수온, 염분, 투명도 및 부유물질 만이 증가하는 경향을 보였으며 이들 변수들이 계절에 따라 다소 차이를 보이는 것으로 나타났다. 특히 봄과 여름에 비해서 가을철에 Mann-Kendall test 및 Sen's Slope estimator에 의해 유의적인 경향을 나타낸 수질변수들이 많았다. 가장 강한 증가 경향을 보인 것은 염분이었으며 봄보다는 여름과 가을에 뚜렷하였다. 투명도도 염분과 유사한 특성을 보였다. 강우량은 조사기간 동안 전체적으로 감소하는 경향을 보였다. 경포호에서 영양염류의 유의적인 감소경향은 그동안 강릉시에서 추진해온 석호 복원사업 및 해수유통 (수중 보철거) 등과 관련이 있는 것으로 판단되나 정확한 원인 규명을 위해서는 보다 면밀한 조사가 수반되어야 할 것으로 사료된다.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회 논문집
• /
• pp.1254-1258
• /
• 2005

Net outflow flux and unit load of pollutants were investigated at a paddy fields area(Soro-ri) with large-scaled plots on loam soil during irrigation seasons of $2001\~2003$. Water samples were collected, and inflow and outflow were .measured at $5\~10$ day intervals during non-storm periods and at $2\~6$ hours intervals during storm events. The average concentration of TP in percolated water was much smaller than that in irrigation and surface outflow water likely due to phosphorus absorption capacity of paddy soils. Net outflow flux in study area was significantly correlated with rainfall and surface outflow discharge. Nutrient flux from Paddy fields can be abated by reduction in outflow surface discharge.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2009년도 춘계학술발표회
• /
• pp.145-147
• /
• 2009

Nutrients in wastewater should be removed prior to release in the receiving waters to prevent the occurrence of eutrophication. In this study, seawater is used to remove ammonia and phosphate by the formation of struvite ($MgNH_{4}PO_{4}{\cdot}6H_{2}O$). It aims to know the optimum conditions for the removal of nutrients using seawater as source of magnesium ions. Experiments were performed using jar tester and pH of ammonium-phosphate solutions were adjusted Samples were drawn at different mixing times. It was shown that simultaneous removal of ammonia and phosphate is rapid, with no significant reduction beyond 10 min of mixing Another important parameter is pH, where range 10-11 showed the optimum nutrient removal. Increase in the volume of seawater, which meant an increase in magnesium ions also lead to better removal.

• Environmental Engineering Research
• /
• 제21권4호
• /
• pp.393-400
• /
• 2016

The aim of this study was to evaluate the biomass production and dairy wastewater treatment using Chlorella vulgaris. The results indicated that the maximum percentages of biochemical oxygen demand, chemical oxygen demand, suspended solids, total nitrogen, and total phosphorus removed were 85.61%, 80.62%, 29.10%, 85.47%, and 65.96%, respectively, in dairy effluent at 10 d. A maximum of 1.23 g/L dry biomass was obtained in 7 d. The biomass productivity was strongly influenced by the nutrient reduction in the dairy effluent. The biodiesel produced by the C. vulgaris in the dairy effluent was in good agreement with the American Society of Testing and Materials-D6751 and European Standards 14214 standards. Therefore, using dairy effluent for microalgal cultures could be a useful and practical strategy for an advanced, environmentally friendly treatment process.

• Environmental Engineering Research
• /
• 제19권1호
• /
• pp.47-57
• /
• 2014

The aim of this paper was to study the effect of five different waste combinations (C/N 15, C/N 20, C/N 25, C/N 30, and control) of sewage sludge coupled with sawdust and cattle manure in a pilot scale rotary drum reactor, during 20 days of the composting process. Our results showed that C/N 30 possesses a higher temperature regime with higher % reduction in moisture content, total organic carbon, soluble biochemical oxygen demand and chemical oxygen demand; and higher % gain in total nitrogen and phosphorus at the end of the composting period implying the total amount of biodegradable organic material is stabilized. In addition, $CO_2$ evolution and oxygen uptake rate decreased during the process, reflecting the stable behavior of the final compost. A Solvita maturity index of 8 indicated that the compost was stable and ready for usage as a soil conditioner. The results indicated that composting can be an alternate technology for the management of sewage sludge disposal.

• 한국관개배수논문집
• /
• 제18권2호
• /
• pp.15-24
• /
• 2011

This study was carried out to analyze characteristics of water quality and correlation among water quality parameters in Idong reservoir used for agricultural water. The pH and concentrations of DO, SS, BOD, COD, TP, Chl-a in Idong reservoir almost met the water quality standards for agricultural water, but TN concentration exceeded the water quality standards for agricultural water. All of water quality items had no significant difference between horizontal points at 95% confidence level and the Idong reservoir was possible to be treated as the single water body. As NIP ratio of the Idong reservoir is 52, TP is a limiting nutrient salt. As TN exceeds the water quality standards, it is required to preserve TP below current state to prevent water bloom by eutrophication. Therefore, reduction of phosphorus from the watershed is necessary for controlling the eutrophication of Idong reservoir.

• Membrane and Water Treatment
• /
• 제11권5호
• /
• pp.345-351
• /
• 2020

Eutrophication of surface waters is commonly caused by excessive inputs of nutrients such as nitrogen and phosphorus. Nakdong River basin was chosen as the study area to investigate the effect of point and non-point source pollution of nitrogen on eutrophication in water body. Non-point source inputs of nitrogen accounted for approximately 84% in the total nitrogen input of the upper Nakdong river watershed, which mainly consists of agricultural land and forests. However, point source inputs of nitrogen accounted for 58~85% in the total nitrogen input of the middle and lower watersheds, including urban area. Therefore, for watershed near urban area, control of point source inputs of nitrogen may be an optimal method to control eutrophication. In this respect, the enforcing reduction of nitrogen in the final effluent of wastewater treatment facilities is needed. On the other hand, to enact more stringent nitrogen regulations, the LOT (limit of technology) and environmental impact should be considered. In this study nitrogen data were analyzed to propose new nitrogen regulations.

• Journal of Plant Biology
• /
• 제19권2호
• /
• pp.37-40
• /
• 1976

The experiment designed to obtain information relative to the favourable levels to apply N.P.K fertilizer was conducted at the hop garden of College of Agriculture, S.N.U. in 1975. The varieties used were 1-year-old Cascade, Hallertau and Shinshuwase. The design of the experiment was a split plot design with 3 replications. Yields were recorded as fresh weight of harvested cones in gram per split plot. The results obtained from the experiment were as follows: 1. The results from analysis of the data for 3 varieties indicated that significant increase in yield were found due to the application of 46g N, 20g P2O5 and 60kg K2O per plant, although higher level thn the above caused a remarkable reduction of yield. 2. The individual fresh weight of harvested cones was significantly increased with application of nitrogen, phosphorus and potash, regardless of fertilizer levels. 3. Analysis of variance for yields showed that there were no significant interaction between fertilizer level and variety, i.e., all varieties used might require the same fertilizer level.