scholarly journals Analysis of Saturation Risk in Sprinkler Irrigation: Case of Cherfech Irrigation Perimeter in Tunisia

2018 ◽  
Vol 10 (2) ◽  
pp. 130
Author(s):  
Samir Yacoubi ◽  
Adel Slatni ◽  
Khemaies Zayani
Keyword(s):  
Sprinkler Irrigation ◽  
Pressure Head ◽  
Field Trials ◽  
Application Rate ◽  
Wetting Front ◽  
Saturated Water Content ◽  
M 12 ◽  
Disc Infiltrometer ◽  
Good Agreement

This study is targeted to the assessment of the saturation risk in sprinkler irrigation. For this purpose, in situ field trials were carried out to infer the saturated hydraulic conductivity (Ks) and sorptivity (S) using the disc infiltrometer method. Since the measured values of Ks are very close to prescribed application rate, caution is required. In a first step, the pressure head at the wetting front (hf) and the useful porosity (θs – θi) are assumed to be constant. Thus, the logarithmic derivation of the sorptivity provides a relation between relative variations of S and Ks. The ponding time (Ts) is estimated from Green and Ampt (1911) and Philip (1957b) infiltration equations. The risk of saturation is deemed to be inexistent inasmuch as simulated values of Ts are greater than the irrigation times practiced in the zone. In a second step, the values of the pressure head at the wetting front and saturated water content were assumed to be variable with soil texture. Simulations of the ponding time were carried out based on Rawls and al. (1981) data. For the recommended sprinkler spacing in the Cherfech perimeter (12 m × 12 m), the simulations show a good agreement between Ts values generated from Green and Ampt and Philip equations for Ks ranging from 1.5 to 6 mm/h. Moreover, it was established that saturation risk due to a gradual texture variation is virtually inexistent in the conditions prevailing in Cherfech perimeter.

Research and application of in-situ control technology for sediment rehabilitation in eutrophic water bodies

2012 ◽  
Vol 65 (7) ◽  
pp. 1190-1199 ◽  
Author(s):  
Bo Liu ◽  
Xuegong Liu ◽  
Jie Yang ◽  
David E. J. Garman ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Algal Growth ◽  
Bentonite Clay ◽  
Field Trials ◽  
Application Rate ◽  
Control Technology ◽  
Overlying Water ◽  
P Release ◽  
In Situ Control ◽  
Limiting Nutrient

Phosphorus (P) is often the limiting nutrient for algal growth, and P in sediments can be released under suitable conditions. To control P release, in-situ control technology with lanthanum (La) modified bentonite clay (Phoslock®) was proposed and its effectiveness was tested and evaluated both in laboratory and field trials. The results of static and dynamic simulation experiments under different environmental conditions showed that with the application rate of Phoslock® at 0.5 kg/m2, the orthophosphate (PO4-P) concentration of the overlying water decreased to a low level (≤0.02 mg/L) within 10 days. Even under anaerobic and high pH (pH = 9.0) conditions, the phosphate release suppression efficiency reached 98.3%, and the P-release rate was −8.20 mg/m2 d (negative value indicates P adsorption by Phoslock®). The monitoring data of the field sediments rehabilitation project were consistent with the results achieved in laboratory experiments, thus showing that the application of Phoslock® could inhibit the internal P release effectively.

Atomic Layer Deposition of LiF and Lithium Ion Conducting (AlF3)(LiF)x Alloys Using Trimethylaluminum, Lithium Hexamethyldisilazide and Hydrogen Fluoride

2017 ◽  
Author(s):  
Younghee Lee ◽  
Daniela M. Piper ◽  
Andrew S. Cavanagh ◽  
Matthias J. Young ◽  
Se-Hee Lee ◽  
...  
Keyword(s):  
Lithium Ion ◽  
Atomic Layer ◽  
Mass Gain ◽  
Alloy Film ◽  
Ex Situ ◽  
X Ray ◽  
Layer Deposition ◽  
Ion Conducting ◽  
Good Agreement

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH<sub>3</sub>)<sub>3</sub> as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF<sub>3</sub> and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF<sub>3</sub>)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film was measured as σ = 7.5 × 10<sup>-6</sup> S/cm.</div>

scholarly journals Millisecond lattice gasification for high-density CO2- and O2-sieving nanopores in single-layer graphene

2021 ◽  
Vol 7 (9) ◽  
pp. eabf0116
Author(s):  
Shiqi Huang ◽  
Shaoxian Li ◽  
Luis Francisco Villalobos ◽  
Mostapha Dakhchoune ◽  
Marina Micari ◽  
...  
Keyword(s):  
Single Layer ◽  
High Density ◽  
Single Layer Graphene ◽  
Pore Density ◽  
Vacancy Defects ◽  
Carbon Gasification ◽  
Layer Graphene ◽  
Gas Molecules ◽  
Good Agreement

Etching single-layer graphene to incorporate a high pore density with sub-angstrom precision in molecular differentiation is critical to realize the promising high-flux separation of similar-sized gas molecules, e.g., CO2 from N2. However, rapid etching kinetics needed to achieve the high pore density is challenging to control for such precision. Here, we report a millisecond carbon gasification chemistry incorporating high density (>1012 cm−2) of functional oxygen clusters that then evolve in CO2-sieving vacancy defects under controlled and predictable gasification conditions. A statistical distribution of nanopore lattice isomers is observed, in good agreement with the theoretical solution to the isomer cataloging problem. The gasification technique is scalable, and a centimeter-scale membrane is demonstrated. Last, molecular cutoff could be adjusted by 0.1 Å by in situ expansion of the vacancy defects in an O2 atmosphere. Large CO2 and O2 permeances (>10,000 and 1000 GPU, respectively) are demonstrated accompanying attractive CO2/N2 and O2/N2 selectivities.

Measuring Reservoir Compaction Through Radioactive Marker Technique

2002 ◽  
Vol 124 (4) ◽  
pp. 269-275
Author(s):  
Paolo Macini ◽  
Ezio Mesini
Keyword(s):  
Land Subsidence ◽  
Reservoir Rock ◽  
Reservoir Compaction ◽  
Critical Comparison ◽  
In Situ Method ◽  
Sufficient Precision ◽  
Good Agreement

Radioactive Marker Technique (RMT), an in-situ method to measure reservoir rock compaction and to evaluate uniaxial compressibility coefficients Cm, is examined here. Recent field applications seems to confirm that RMT-derived Cm’s match with sufficient precision with those calculated from land subsidence observed over the field by means of geodetic surveys, but are not always in good agreement with those derived from lab measurements. In particular, here is reported an application of RMT in the Italian Adriatic offshore, which highlights the discrepancies of Cm’s measurements from lab and RMT. At present, these discrepancies aren’t thoroughly understood, so, from an applicative standpoint, it is still necessary to perform a critical comparison and integration between both set of data.

scholarly journals Integrative analysis of <i>Geobacter</i> spp. and sulfate-reducing bacteria during uranium bioremediation

2012 ◽  
Vol 9 (3) ◽  
pp. 1033-1040 ◽  
Author(s):  
M. Barlett ◽  
K. Zhuang ◽  
R. Mahadevan ◽  
D. Lovley
Keyword(s):  
Sulfate Reducing Bacteria ◽  
Field Trials ◽  
Second Phase ◽  
Sulfate Reducing ◽  
Organic Electron ◽  
Poor Understanding ◽  
Key Factor ◽  
Reducing Bacteria ◽  
The Impact

Abstract. Enhancing microbial U(VI) reduction with the addition of organic electron donors is a promising strategy for immobilizing uranium in contaminated groundwaters, but has yet to be optimized because of a poor understanding of the factors controlling the growth of various microbial communities during bioremediation. In previous field trials in which acetate was added to the subsurface, there were two distinct phases: an initial phase in which acetate-oxidizing, U(VI)-reducing Geobacter predominated and U(VI) was effectively reduced and a second phase in which acetate-oxidizing sulfate reducing bacteria (SRB) predominated and U(VI) reduction was poor. The interaction of Geobacter and SRB was investigated both in sediment incubations that mimicked in situ bioremediation and with in silico metabolic modeling. In sediment incubations, Geobacter grew quickly but then declined in numbers as the microbially reducible Fe(III) was depleted whereas the SRB grow more slowly and reached dominance after 30–40 days. Modeling predicted a similar outcome. Additional modeling in which the relative initial percentages of the Geobacter and SRB were varied indicated that there was little to no competitive interaction between Geobacter and SRB when acetate was abundant. Further simulations suggested that the addition of Fe(III) would revive the Geobacter, but have little to no effect on the SRB. This result was confirmed experimentally. The results demonstrate that it is possible to predict the impact of amendments on important components of the subsurface microbial community during groundwater bioremediation. The finding that Fe(III) availability, rather than competition with SRB, is the key factor limiting the activity of Geobacter during in situ uranium bioremediation will aid in the design of improved uranium bioremediation strategies.

scholarly journals Genotype selection and addition of fertilizer increases grain yield in upland rice in Suriname

2017 ◽  
Vol 47 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Adriano Stephan NASCENTE ◽  
Ruby KROMOCARDI
Keyword(s):  
Grain Yield ◽  
Management Practices ◽  
Upland Rice ◽  
Block Design ◽  
Field Trials ◽  
Application Rate ◽  
Rice Grain ◽  
Rice Varieties ◽  
Local Conditions ◽  
Randomized Block Design

ABSTRACT The upland rice farmers in Suriname use local varieties and low level technologies in the field. As a result, the upland rice grain yield is low, at about 1 000 kg ha-1. Our objective was to evaluate the use of upland rice cultivars from Suriname and Brazil, and the effect of nitrogen, N, phosphorus, P, and potassium, K, fertilizers on cultivation variables. We undertook four field trials in the Victoria Area, in the Brokopondo District, using a randomized block design each with four replications. The most productive rice varieties were BRS Esmeralda (grain yield 2 903 kg ha-1) and BRS Sertaneja (2 802 kg ha-1). The highest grain yield of 2 620 kg ha-1 was achieved with a top dressing application of 76.41 kg N ha-1 20 days after sowing. For P, the highest grain yield of 3 085 kg ha-1 was achieved with application of 98.06 kg ha-1 P2O5 applied at sowing. An application rate of 31.45 kg ha-1 of K2O at sowing achieved the highest grain yield of 2 952 kg ha-1. Together, these application rates of N, P and K resulted in rice grain yield of about 3 000 kg ha-1, which is three times greater than the national average for upland rice. We demonstrate that the use of improved rice varieties matched to the local conditions, and application of appropriate fertilizers, are management practices that can result in significant increases in rice grain yield in Suriname.

scholarly journals In-situ measurement of reactive hydrocarbons at Hohenpeissenberg with comprehensive gas chromatography (GCxGC-FID): use in estimating HO and NO<sub>3</sub>

2006 ◽  
Vol 6 (4) ◽  
pp. 8155-8188
Author(s):  
S. Bartenbach ◽  
J. Williams ◽  
C. Plass-Dülmer ◽  
H. Berresheim ◽  
J. Lelieveld
Keyword(s):  
Mean Value ◽  
Time Data ◽  
Night Time ◽  
Radical Species ◽  
Diurnal Cycles ◽  
Meteorological Observatory ◽  
Variate Analysis ◽  
The Relationship ◽  
Good Agreement

Abstract. During a field campaign at the Meteorological Observatory Hohenpeissenberg (MOHp) in July 2004, VOCs were measured using GCxGC-FID. Comparison to routinely made GC-MS measurements showed good agreement for a variety of anthropogenic and biogenic ambient VOCs ranging in concentration from below the detection limit (0.1 pmol mol−1) to 180 pmol mol−1. Pronounced diurnal cycles were found for both the biogenic and anthropogenic compounds, driven for the most part by the daily rise and fall of the boundary layer over the station. For the reactive compounds (lifetimes <2 days), a significant, non-zero dependency of the variability on lifetime was found, indicating that chemistry (as opposed to transport alone) was playing a role in determining the ambient VOC concentrations. The relationship was exploited using a single-variate analysis to derive a daytime mean value of HO (5.3±1.4×106 molecules cm−3), which compares well to that measured at the site, 3.2±2.3×106 molecules cm−3. The analysis was extended to the night time data to estimate concentrations for NO3 (1.47±0.2×108 molecules cm−3), which is not measured at the site. The feasibility of this approach for environments dominated by emissions of short-lived VOCs to estimate ambient levels of radical species is discussed.

scholarly journals Flight Demonstration of a 2-Micron, Double Plused CO2 IPDA Lidar Instrument

2020 ◽  
Vol 237 ◽  
pp. 03013
Author(s):  
Jirong Yu ◽  
Mulugeta Petros ◽  
Upendra Singh ◽  
Tamer Refaat ◽  
Karl Reithmaier ◽  
...  
Keyword(s):  
Column Density ◽  
High Energy ◽  
Density Difference ◽  
Lidar Measurement ◽  
Differential Absorption ◽  
Air Samples ◽  
Lidar Measurements ◽  
Langley Research Center ◽  
Good Agreement

NASA Langley Research Center (LaRC) developed a double pulsed, high energy 2-micron Integrated Path Differential Absorption (IPDA) lidar instrument to measure atmospheric CO2 column density. The 2-μm double pulsed IPDA lidar was flown ten times in March and April of 2014. It was determined that the IPDA lidar measurement is in good agreement with an in-situ CO2 measurement by a collocated NOAA flight. The average column CO2 density difference between the IPDA lidar measurements and the NOAA air samples is 1.48ppm in the flight altitudes of 3 to 6.1 km.

scholarly journals Comparison between sprinkler irrigation and natural rainfall based on droplet diameter

2016 ◽  
Vol 14 (1) ◽  
pp. e1201 ◽  
Author(s):  
MaoSheng Ge ◽  
Pute Wu ◽  
Delan Zhu ◽  
Daniel P. Ames
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Droplet Diameter ◽  
Vertical Component ◽  
Radial Distance ◽  
Sprinkler Irrigation ◽  
Application Rate ◽  
Horizontal Component ◽  
Natural Rainfall ◽  
Actual Field

<p>An indoor experiment was conducted to analyze the movement characteristics of different sized droplets and their influence on water application rate distribution and kinetic energy distribution. Radial droplets emitted from a Nelson D3000 sprinkler nozzle under 66.3, 84.8, and 103.3 kPa were measured in terms of droplet velocity, landing angle, and droplet kinetic energy and results were compared to natural rainfall characteristics. Results indicate that sprinkler irrigation droplet landing velocity for all sizes of droplets is not related to nozzle pressure and the values of landing velocity are very close to that of natural rainfall. The velocity horizontal component increases with radial distance while the velocity vertical component decreases with radial distance. Additionally, landing angle of all droplet sizes decreases with radial distance. The kinetic energy is decomposed into vertical component and horizontal component due to the oblique angles of droplet impact on the surface soil, and this may aggravate soil erosion. Therefore the actual oblique angle of impact should be considered in actual field conditions and measures should be taken for remediation of soil erosion if necessary.</p>

scholarly journals Long-Term Patterns and Trends of Shortwave Global Irradiance over the Euro-Mediterranean Region

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1431
Author(s):  
Elissavet Galanaki ◽  
George Emmanouil ◽  
Konstantinos Lagouvardos ◽  
Vassiliki Kotroni
Keyword(s):  
Mediterranean Region ◽  
Spatiotemporal Variability ◽  
Reanalysis Dataset ◽  
Global Irradiance ◽  
Seasonal Basis ◽  
Region 10 ◽  
Annual Scale ◽  
Good Agreement

The spatiotemporal patterns and trends of shortwave global irradiance (SWGI) are a crucial factor affecting not only the climate but also sectors of the economy. In this work, the ERA5-Land reanalysis dataset is employed and evaluated against in situ measurements from a dense network of surface stations operated by the National Observatory of Athens over Greece, revealing a good agreement between the two datasets. Then, the spatiotemporal variability of SWGI is investigated over the Euro-Mediterranean region (10° W–42° E and 30° N–52° N) for a 40-year period (1981–2020). SWGI exhibits a smooth latitudinal variability from north to south of −5.4 W/m2/degree on an annual scale, while it varies significantly on a seasonal basis and is almost four times lower in the winter than in the summer. The SWGI trend during the analyzed period was found to be positive and statistically significant at the 95% confidence level. Spring and summer are the periods where positive and the strongest rates of SWGI trends are evident, while in the winter and autumn, negative or neutral trends were found. The increasing SWGI trend shows a slowdown during the beginning of the 2000s in all seasons, except autumn. The SWGI trend decreases by about −0.06 W/m2/decade every 100 m of elevation increase.

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