Showing 17 results for Concentration
M. Shivazad, A. Seidavy,
Volume 5, Issue 1 (4-2001)
Abstract
An experiment was conducted in order to study the possibility of compensatory growth by changing dietary nutrients concentration in the female Arian broiler chicks using a completely randomized design by means of standard and diluted diets. By standard diet is meant diet recommended by Arian’s guide catalogue and by diluted diet is meant the diet used in Iran broiler farms. However, both diets contain the same nutrient/energy ratios. Chicks in the seven treatments received in their starter, grower and finisher stages standard and standard and standard, standard and diluted and diluted, diluted and standard and diluted, diluted and diluted and standard, diluted and standard and standard, diluted and diluted and diluted, standard and standard and diluted respectively. Furthermore each treatment contained three replicants and each replicant contained 30 chicks. This experiment was conducted in autumn using 630 female Arian broiler chicks for eight weeks.
It was concluded that weight gain of chicks receiving standard diets during all stages of their growing period was the same as the chicks receiving diluted diet during their starter period and standard diets during grower and finisher periods. Feed consumption and feed conversion ratio of these treatments were statistically lower than other treatment groups. Furthermore, production index and percentage of mortality was better than other treatment groups. Likewise, viscera% and abdominal fat% remained significantly constant in all treatment groups. But the cost of feed per unit of live body weight was lower in the treatment receiving diluted diets in all three stages of their growing period.
M. R. Chakerolhosseini, A. Ronaghi, M. Maftoun, N. Karimian,
Volume 6, Issue 4 (1-2003)
Abstract
Iron (Fe) availability is low in calcareous soils of Iran due to high pH levels and presence of excessive amounts of CaCO3. Overfertilization by phosphorus (P) fertilizers may also decrease Fe availability. The objective of this study was to evaluate the effects of P, Fe and their interactions on the growth and chemical composition of soybean [Glycine max (L.) Merrill] under greenhouse conditions. Treatments consisted of a factorial arrangement of P rates (0, 40, 80, 120 and 160 mg kg-1 as KH2PO4) and Fe rates (0, 2.5, 5 and 10 mg kg-1 as FeEDDHA) in a completely randomized design with four replications. Plants were grown for 8 weeks in a loamy soil, classified as Chitgar series (fine-loamy, carbonatic, thermic, Typic Calcixerepts). Results showed that P application up to 80 and Fe at 2.5 mg kg-1 increased shoot dry matter. Phosphorus concentration, total uptake and P:Fe ratio in soybean increased by P application but decreased by Fe application. Application of Fe up to 2.5 mg kg-1 increased dry matter but decreased it at higher rates. Concentration and total uptake of Fe increased by Fe application but decreased by P application. Interaction of P and Fe had no effect on shoot dry matter. Zinc (Zn) and copper (Cu) concentrations decreased significantly when P was added and manganese (Mn) concentration increased up to 40 mg P kg-1 but decreased at higher rates. Iron application had no effect on soybean Zn and Cu concentrations but decreased Mn concentration at all rates. Prior to any fertilizer recommendations, it is necessary to study the effects of P, Fe and their interactions on soybean under field conditions.
S. M. A. Razavi, S. A. Mortazavi, S. M. Mousavi,
Volume 10, Issue 2 (7-2006)
Abstract
In this study, the effect of transmembrane pressure (TMP) on flux decline and protein rejection due to concentration polarization and fouling (adsorption) resistances during ultrafiltration of reconstituted skimmilk was investigated. UF experiments were carried out using a pilot plant unit equipped with spiral wound module and polysulfonamide UF membrane. A three-stage experimental strategy based on a resistance-in-series model (boundary layer-adsorption) was used to seperately determine the hydraulic membrane resistance, concentration polarization and fouling resistances. The results showed that increasing TMP had no effect on initial flux reduction (Jrt), but flux decline in each TMP was greatly due to concentration polarization, and fouling has a small role in flux decline, whereas dynamic response of flux decline proved that increasing Jrt during operation is due to fouling. The influence of TMP on resistances showed that total hydraulic resistance and reversible fouling resistance are increased with increasing TMP, but intrinsic membrane resistance and irreversible fouling resistance did not change. Increasing the total hydraulic resistance with time resulted in increasing both reversible and irreversible fouling resistances. Increasing TMP or operation time had no significant effect on protein rejection, but only led to an increase about 1-4 percent.
N. Mirghaffari, H. Shariatmadari,
Volume 11, Issue 41 (10-2007)
Abstract
Concentration of soluble fluoride in groundwater, soil, and some crops in Isfahan region was determined by Ion Selective Electrode (ISE) method. The mean fluoride concentration of water samples in the study area was 0.3 and 0.05 mg L-1 in the spring and summer, respectively. These values are in an acceptable limit for irrigation, whereas for drinking water, they are in deficiency range. The average and maximum concentrations of soluble fluoride in soil samples were 1.0 and 3.2 mg kg-1, respectively. In general, the spatial distribution of fluoride in soils showed that fluoride content around major industrial centers such as Isfahan Steel Factory, Mobarakeh Steel Co., and Isfahan oil refinery was higher than other sites. The minimum and maximum fluoride contents of crops were observed in alfalfa as 0.2 and in corn as 4.2 mg kg-1, respectively. Tomato had the highest mean concentration of fluoride as 3.6 mg kg-1. The fluoride concentration in plants positively correlated with the fluoride concentration in irrigation water and soil (P < 0.01) and negatively correlated with cation exchange capacity of soil (P < 0.05).
N. Sahebzadeh, R. Ebadi, J. Khajehali,
Volume 12, Issue 45 (10-2008)
Abstract
Due to injuries of pesticides to natural enemies of pests and pollinator insects, especially honeybees, during the flowering periods, it is essential to protect them. Application of chemical compounds along with the pesticides on the plants could repel the non-target insects from the sprayed areas for sometime and lessen the hazards of pesticides to them. In this study, ten repellent chemicals whose repellency effect was proven in the laboratory in previous studies were screened in the field. Among tested repellents including, Acetophenon, Methyl ethyl ketone, Methyl isobutyl ketone, Cyclohexanone, Acetyl acetone, Methylsalicylate, Propionic anhydride, Maleic anhydrate, 2- Ethylhexylamine, and Dibutylamine, it was revealed that amino group compounds including 2- Ethylhexylamine and Dibutylamine and esteric compound, Methylsalicilate had the highest repellency effect on the honeybees under the field conditions. Repellency effect of these compounds was greater at 15 pm than other sampling times. Repellency effects of different concentrations of these three compounds, when mixed with 0.5% concentration of fixative compounds, showed that the mixture of 2- Ethylhexylamine with Benzylbenzoate, Dibutylphthalate and Benzylalcohole with concentration of 0.17, 0.4 and 0.03 % respectively, the mixture of Dibutylamine at the concentration of 1% with Benzylbenzoate and Dibutylphthalate and at the concentration of 0.08% and higher with Benzylalcohole, and also mixture of Methylsalicilate at the concentration of 1.8 % and higher with Benzylalcohole, all have repellency effect of more than 70% under the field conditions.
M. R. Asgharipour, A. Ghanbari Bonjar, H. Azizmoghadam, A. R. Sirousmehr, M. Heidari,
Volume 16, Issue 62 (3-2013)
Abstract
In this study the effects of irrigation with raw or diluted municipal effluents along with foliar micro-nutrients fertilizer spray were examined on the growth, yield and mineral nutrient in foxtail millet plants. The experimental design was a split-plot with three irrigation sources (namely raw sewage, 50% diluted sewage and well water) as main-treatment and four combinations of Mn and Zn foliar spraying as sub-treatments, which were applied with three replications. The experiment was conducted at the Zabol University research farm during 2009. The applied municipal effluents contained higher levels of macro and micro-nutrients than the well water. The experimental results indicated that irrigation of plants by raw or diluted sewage improved the measured growth parameters and productivity of foxtail millet plants. In addition macro and micro-nutrients concentrations were improved. These improvements were attributed to the presence of high levels of essential nutrients such as nitrogen, phosphorus, and organic matters in wastewater. Manganese and Zn supplied through sewage water alone were not able to raise the productivity of millet to the level obtained through fertilizers at the recommended level, which indicated that additional nutrients through fertilizers are required to obtain higher productivity of millet under sewage farming. Despite the differences in nutrients concentration among different irrigation water sources, the micro-nutrients foliar spray did not affect concentration of macro and micro-nutrients in foxtail millet plant. Overall, the results suggest that municipal sewage could be efficiently utilized as an important source of water and nutrients in growing foxtail millet Sewage water irrigation did not have any appreciable harmful effect on crop productivity.
M. Khastar-Borujeni, H. Samadi, K. Esmaili,
Volume 18, Issue 68 (9-2014)
Abstract
Due to adhesion properties of fine sediments, chemical physics factors of fluid can cause changes in the behavior of sediments. In this study, the characteristics of sediment deposition with three levels of waste water, different shear stresses and initial sediment concentrations were investigated in the annular flume located at Hydraulic Laboratory of Shahrekord University. Sediments for experiments were taken from the Pirbalut dam reservoir. The velocity and the shear stress profiles were measured using an Acoustic Doppler Velocimeter (ADV).The results showed that the concentration of cohesive sediment was decreased with time and finally it reached an equilibrium concentration of sediment. The equilibrium concentrations to initial concentration (Ceq/C0) in special shear stress, for different initial sediment concentrations and different levels of waste water were almost the same. Equilibrium concentration was dependent on the initial concentration sediment. Threshold and full deposition shear stresses were increased in waste water. Shear stresses of full deposition for 0, 30 and 60 % wastewater were 0.053, 0.075 and 0.070 N/m2, respectively. Also, for specified levels of waste water, the values
were obtained 10, 15 and 17, in which the suspended sediments would remain.
Kh. Hosseini, M. Kheirkhahn,
Volume 18, Issue 70 (3-2015)
Abstract
Cohesive sediments have large specific surfaces which enable them to absorb other cohesive sediments and polar particles such as mud and sodium. Floccules form by joining these particles. The behavior of cohesive sediments in aquatic environments is completely different from that of granular sediments. Under certain value of shear stress, the structure formed from cohesive sediments is divided into smaller particles, which can be eroded easily. Up to now, researchers have proposed empirical formulas which correlate the rate of erosion to the bed shear stress and the rheological characteristics of cohesive sediments. In this study, the calibration and verification tests are performed on Mike21 software to attain the results more adjusted with the experimental data. Afterwards, the data are developed by the model and converted to the dimensionless form. Finally, an exponential function is proposed for the erosion rate in cohesive sediments. It is found that the coefficient of determination is 0.99
K. Asgari, S. H. Tabatabaei, P. Najafi, Sh. Kiani,
Volume 20, Issue 78 (1-2017)
Abstract
Constant use of treated wastewater (TWW) for irrigation over long periods may cause buildup of heavy metals up to toxic levels for plants, animals, and entails environmental hazards in different aspects. The aim of this study was to assess the effect of using a deep emitter installation on lowering the potential heavy metal accumulation in soil and wheat grain, and health risk under drip irrigation with treated municipal wastewater. A field experiment was conducted according to a split block design with two treatments (fresh and wastewater) and three sub treatments (0, 15 and 30 cm depth of emitters) in four replicates in Esfahan, Iran. Soil samples were collected before planting (initial value) and after harvesting (final value) in each year. Elemental concentrations (Cu, Zn, Cd, Pb, Cr, and Ni) in soil and grain were determined using an atomic absorption spectrophotometer. A pollution load index (PLI) showed that there was not substantial buildup of heavy metals in the wastewater-irrigated soils compared to the freshwater-irrigated soils. Cu, Pb, Cr and Zn concentrations in wheat grain were within permissible EPA limits, but concentrations of Cr was above the safe limits of EPA. In addition, concentrations of Ni in wheat grain were several folds higher than EPA standards. A health risk index (HRI) which is usually adopted to assess the health risk to hazard materials in foods showed values higher than 1 for Cd and Cu, whereas children might also be exposed to health risk of Cd, Cu and Cr. Based on aforementioned results, it can be concluded that the depth of emitter in drip irrigation does not play a significant role in the accumulation of heavy metals from TWW in our sandy loam soil.
Z. Mollaee, J. Zahiri, S. Jalili, M. R. Ansari, A. Taghizadeh,
Volume 22, Issue 2 (9-2018)
Abstract
Spectral Reflectance of suspended sediment concentration (SSC) remotely sensed by satellite images is an alternative and economically efficient method to measure SSC in inland waters such as rivers and lakes, coastal waters, and oceans. This paper retrieved SSC from satellite remote sensing imagery using radial basis function networks (RBF). In-situ measurement of SSC, water flow data, as well as MODIS band 1 and band ratio of band 2 to 1 were the inputs of the RBF. A multi-regression method was also used to make a relationship between the in-situ data and the water reflectance data retrieved from MODIS bands. The results showed that RBF had the best SSC prediction error (RMSE=0.19), as compared to the multi-regression and sediment rating curve methods, with the RMSE of 0.29 and 0.21, respectively.
N. Sadeghian, A. Vaezi, A. Majnooni Heris,
Volume 24, Issue 1 (5-2020)
Abstract
Few studies have been done regarding the role of the raindrop in the hydrodinamic mechanism of soil erosion. In this study, rainfall simulation experiments were conducted to evaluate the role of raindrop in runoff discharge, sediment concentration and hydraulic properties of flow under four slope gradients (5, 10, 15 and 20%) in a clay soil using a 90 mm.h-1 rainfall intensity to reach the steady state flow. Soil sample was packed into the erosion flume with 0.3m× 0.4m × 4 m in dimensions and tested under two soil surface conditions: one with raindrop impact and one without raindrop impact. The results showed that runoff discharge, sediment concentration, flow depth, shear stress, stream power, Reynolds number and runoff velocity under without raindrop impact condition were significantly lower than those in the condition with the raindrop impact with a factor of 0.62 to 3.54, 0.08 to 11.83, 0.91 to 0.96, 0.26 to 3.25, 0.52 to 4.45, and 0.36 to 3.27, 0.23 to 0.79 times, respectively; on the other hand, the Darcy Wysbach, Chezy and Manning coefficients were increased significantly under without raindrop impact (P<0.01). Flow velocity was the key hydraulic parameter strongly affecting the hydraulic properties. These findings indicated the importance of raindrop impact in the detachment rate of soil particles through the change of the hydraulic characteristics. This study also revealed the key role of raindrop impact on the runoff hydraulic characteristics, as well as particle detachments rate in rills. Information about the role of raindrop impact is a substantial step in modeling the rill erosion. Therefore, elimination of raindrops impact, especially in the steep slopes, with the conservation of natural vegetation cover can sufficiently prevent runoff production as well as the particle detachment rate.
N. Hasanzadeh, L. Gholami, A. Khaledi Darvishan, H. Yonesi,
Volume 25, Issue 1 (5-2021)
Abstract
Soil erosion is one of the most serious environmental issues in the world, causing soil degradation, reduction of land productivity, increasing flood, water pollution and pollutions transportation; it is also a serious threat to sustainable development in the world. Therefore, the soil conservation and the prevention of soil erosion and use of conditioners as the nanoclay can be considered as a solution to improve land productivity and protect environment. The present study was, therefore, conducted to address the effect of the application of montmorillonite nanoclay with three rates of 0.03, 0.06 and 0.09 t ha-1 on changing runoff and soil loss variables under laboratory conditions. The results showed that the nanoclay with the rate of 0.03 t ha-1 could decrease the runoff coefficient, soil loss and sediment concentration with the rate of 40.65, 88.38 and 82.19 percent, respectively. The average of soil loss in control treatment and conservation treatments of nanoclay with various rates was measured to be 3.76, 0.44, 1.33 and 3.16 g, respectively. Also, the results showed that the most sediment concentration was the control treatment with the rate of 5.84 g l-1 and the conservation treatments with nanoclay in the applied rates was 1.04, 3.47 and 2.96 g l-1, respectively. Also, the results showed that the nanoclay effect was significant on changing the soil loss and sediment concentration at the level of 99 percent. Finally, due to the effect, the use of this conditioner in natural conditions and investigation of the effects on environment and aggregates stability are recommended.
H. Noori Khaje Balagh, F. Mousavi,
Volume 25, Issue 3 (12-2021)
Abstract
In the present study, CanESM2 climate change model and stormwater management model (SWMM) were employed to investigate the climate change effects on the quantity and quality of urban runoff in a part of Karaj watershed, Alborz Province. The base period (1985-2005) and future period (2020-2040) are considered for this purpose. Based on the existing main and lateral drainage system and to be more accurate, the watershed was divided into 37 sub-watersheds by ArcGIS software. To simulate rainfall-runoff, the intensity-duration-frequency (IDF) curve has been prepared for a 2-hour duration and 10-year return period, for the base period and RCP2.6 and RCP8.5 climate change scenarios based on the obtained precipitation data from Karaj synoptic station. Results showed that mean 24-hour precipitation values in RCP2.6 and RCP8.5 scenarios will increase by 21% and 11%, respectively, and maximum 24-hour precipitation values will decrease by 17% and 23%, respectively, as compared to the observed values in the base period. Also, based on the results of quantitative and qualitative runoff modeling in the study watershed, and according to the outflow hydrograph in the RCP2.6 and RCP8.5 scenarios, the outlet runoff discharge will decrease by 5.8% and 7.1%, respectively. Also, the flooded areas in the watershed will decrease by 13% and 15.28%, respectively. The concentration of pollutants in the RCP2.6 and RCP8.5 scenarios, compared to the base period, including total suspended solids (TSS), will increase by 7.48% and 9.24%, total nitrogen (TN) will increase by 6.93% and 8.48%, and lead (Pb) will increase by 7.32% and 8.91%, respectively.
L. Gholami, A. Khaledi Darvisan, N. Karimi,
Volume 25, Issue 3 (12-2021)
Abstract
Soil loss can cause many intra-regional and extra-regional problems, on the other hand, the effect of soil moisture on processes of soil loss and sediment yield for the identification and simulation of soil hydrological response is necessary. Therefore, the application of soil conditioners is essential for soil and water conservation. The present study was conducted to investigate the effect of soil conditioners of vermicompost and nano-manure on variables of soil loss and sediment concentration at moistures of air-dried, 15 and 30%, and rainfall intensities of 50 and 90 mm h-1. The obtained results in addition to confirmation of the significant effect of each conservation treatment at the level of 99 percent on the intended components showed that the conservation treatment of vermicompost compared to nano-manure treatment had more effect on measured variables. Also, the conservation treatment of vermicompost could decrease the soil loss at soil moisture air-dried, 15, and 30 percent with rates of 72.15, 66.63, and 78.76 percent (50 mm h-1), respectively, and 45.01, 35.57, and 10.45 percent (of 90 mm h-1), respectively. The effect of conservation treatments, soil moistures, and rainfall intensity and the interaction effects of conservation treatments × rainfall intensity and rainfall intensity × soil moisture on changes of soil loss and sediment concentration were significant at the level of 99 percent. The application of vermicompost and nano-manure had acceptable results on studied parameters but the vermicompost effect was more than nano-manure. Therefore, due to the widespread use of different types of conditioners, nowadays, it is needed to move the application feasibility of conditioners such as vermicompost and nano-manure that these have not the adverse effects of environmental.
N. Dalvand, S. Sobhan Ardakani, M. Kiani Sadr, M. Cheraghi, B. Lorestani,
Volume 26, Issue 3 (12-2022)
Abstract
Individuals spend a lot of time indoors, thus they can generally be exposed to polycyclic aromatic hydrocarbons (PAHs) as a teratogen, mutagen, and carcinogen pollutants with the potential for environmental and also human health risks. Therefore, the current study was performed to analyze PAHs in household dust samples of the city of Khorramabad, Iran in 2019. A total of 50 indoor dust samples were collected from 10 sampling sites. After the extraction of analytes, the gas chromatography/mass spectrometry (GC–MS) method was used to determine PAHs in the studied samples. All statistical analyses were performed by SPSS software. The results showed that 16 priority PAHs were detected in the samples with the minimum, maximum, and mean values of 14.0, 23.3, and 19.2 µg/kg. Also, based on the results the mean contents of detected PAHs were lower than the maximum permissible concentration (MPC) established by MHWS and Iran DOE. In conclusion, due to exposure risks of PAHs, regular and periodic analysis of these pollutants in different environmental samples including soil, sediment, dust, particulate matter, air, water, and tissues of living organisms for environmental and human health maintenance is recommended.
S. Jalali, K. Nosrati, Z. Fathi,
Volume 27, Issue 2 (9-2023)
Abstract
The geomorphic characteristics of the watersheds are interrelated and the temporal and spatial scale in the form of season and sub-basins affect the concentration of suspended sediment. One of the objectives of this study was to investigate the relationship between suspended sediment concentration and watershed characteristics of Kan River using principal components regression and to recognize the effect of seasons and sub-basins on sediment concentration. The concentration of suspended sediment during four rainfall-runoff events in three seasons and in sub-basins was measured and calculated. The sixteen physiographic and land use characteristics were determined in the sub-basins and the main factors were identified and the scores of each factor for each feature were calculated using principal component analysis (PCA). The results of variance analysis showed that the concentration of suspended sediment was significant in terms of time scale and spring had the highest rate of sedimentation. Redundancy analysis and canonical analysis on the properties that participate in the first factor (PC1) showed the characteristics of the percentage of erodible formation, relatively erodible formation, and percentage of free construction activity, respectively. Road (slope leveling) and stream length are the most essential attributes of sub-basins in the production and concentration of suspended sediment in the study area.
M.a. Abdullahi, J. Abedi Koupai, M.m Matinzadeh,
Volume 28, Issue 3 (10-2024)
Abstract
Today, the problems related to floods and inundation have increased, particularly in urban areas due to climate change, global warming, and the change in precipitation from snow to rain. Therefore, there has also been an increasing focus on rainfall-runoff simulation models to manage, reduce, and solve these problems. This research utilized SewerGEMS software to explore different scenarios to evaluate the model's performance based on the number of sub-basins (2 and 8) and return periods (2 and 5 years). Additionally, four methods of calculating concentration time (SCSlag, Kirpich, Bransby Williams, and Carter) were compared to simulate flood hydrographs in Shahrekord city. The results indicated that increasing the return period from 2 to 5 years leads to an increase in peak discharge in all scenarios. Furthermore, based on the calculated continuity error, the Kirpich method is preferred to estimate the concentration-time in scenarios with more sub-basins and smaller areas. For the 2-year return period, a continuity error of 4% was calculated for the scenario with 2 sub-basins, while for the 5-year return period, the continuity error was 19%. On the other hand, the SCSlag method is preferred to estimate the concentration-time in scenarios with fewer sub-basins and larger areas. For the scenario with 8 sub-basins, a continuity error of 16% was calculated for the 2-year return period, and 11% for the 5-year return period.
