A new centrifuge permeameter was developed with the specific objective of expediting the measurement of the hydraulic characteristics of unsaturated soils. The development, theoretical basis, and ...typical results associated with using the centrifuge permeameter for concurrent determination of the soil-water retention curve (SWRC) and hydraulic conductivity function (
K
function) of unsaturated soils are presented in this paper. Components developed for the centrifuge permeameter are described, including the centrifuge, permeameter, water flow control system, and instrumentation used to concurrently and nondestructively measure the infiltration rate (flow pump and outflow transducer), volumetric water content (time domain reflectometry), and matric suction (tensiometers) in flight during steady-state infiltration. A companion paper focuses on definition of the SWRC and
K
function for a clay soil using the procedures described in this paper. While conventional geotechnical centrifuges are used to reproduce the response of earth structure prototypes, the centrifuge developed in this study is used to accelerate flow processes. Accordingly, it required a comparatively small radius (0.7 m) but high angular velocity (up to 875 rpm or 600
g
’s) to impart a wide range of hydraulic gradients to an unsaturated soil specimen. Analytical solutions to Richards’ equation in the centrifuge indicate that steady-state infiltration allows direct determination of the relationships between suction, volumetric water content, and hydraulic conductivity from the instrumentation results. Typical instrumentation results during a drying stage are presented to illustrate determination of data points on the SWRC and
K
function at steady state. These results were found to be consistent with analytical flow solutions.
Capillary waves are frequently used to measure the surface tension of liquids. However, this approach has not found wide application in the manufacture of modern commercial tensiometers because of ...the limitations imposed by capillary wave excitation techniques and the labor input associated with its practical implementation. In this paper we introduce a modified version of the capillary wave method which allows one to avoid the existing limitations and disadvantages. The distinguishing features of the proposed technique are as follows: acoustic wave generation and application of an interferometry technique for 3D surface profile reconstruction. A dynamic speaker with controlled vibration frequency and amplitude is used to produce acoustic vibrations. Application of a conventional Fizeau interferometer and the spatial phase shifting method makes it possible to perform surface form measurements with a high accuracy. For calculating wavelengths and the damping co-efficient, the surface profile is fitted with a decaying cylindrical wave equation. The accuracy of surface tension measurement by the modified capillary wave technique is 0.3 %. Owing to the non-contact way of wave generation and the small amounts of the examined fluid, the proposed method can be used in different studies.
Purpose
Previous studies in the Mezquital Valley evidenced that irrigation with untreated sewage effluent supplies two- to tenfold larger nitrogen doses to crops than common fertilizer ...recommendations. However, nitrate concentrations in the groundwater are only slightly above threshold concentrations for drinking water. To understand the N dynamics in this agroecosystem, we quantified nitrogen inputs, outputs, and transformations within the rooting zone and in the vadose zone down to the aquifer (i.e., in the critical zone).
Materials and methods
Single irrigation events were monitored in three different fields cropped with either annual rye grass (
Lolium rigidum
) or oats (
Avena sativa
L.) harvested for fodder. For each irrigation event, the total amount of water entering and leaving the field was quantified with a flowmeter. Soil pore water was collected with either microsuction cups or observation wells and groundwater was sampled at two wells. All water samples were analyzed for total nitrogen (Nt), ammonium nitrogen (NH
4
+
–N), nitrate nitrogen (NO
3
−
–N), chloride (Cl
−1
), and pH. Organic N was calculated as the difference between total N and inorganic N. The water tension and the soil water content were monitored before, during, and after the irrigation with tensiometers and TDR probes, respectively, installed at different depths and at three sites within each field. Batch experiments were conducted to assess the NH
4
+
adsorption capacity of the soils.
Results and discussion
The irrigations added 537 to 727 kg ha
−1
N in form of organic N (40 %) and NH
4
+
–N (60 %) to the fields. Crops absorbed 65 % of the N and 31 to 66 kg NO
3
−
–N ha
−1
leached out beyond the rooting zone (>40 to 130 cm). Batch experiments evidenced an ammonium adsorption capacity of 43 and 53 % of the input ammonium mass. Nitrification dominated over denitrification as the water infiltrated through the soil, evidenced by changes in nitrate concentrations and pH values in the soil pore water. The behavior of the total N/Cl ratio with depth indicated possible N losses due to NH
3
volatilization at the field surface, a temporal withdrawal of N from the soil solution due to NH
4
+
–N adsorption in the rooting zone, as well as probable denitrification losses in the vadose zone.
Conclusions
Although the studied agroecosystem muses the large N inputs relative efficiently, between 7 and 10 % of the added N with each irrigation leaches beyond the crop root zone as nitrate. This is triggered by overflow irrigation, since up to 8,699,000 L of water with N concentrations of up to 50 mg total N L
−1
infiltrate rapidly through macropores beyond the rooting zone. Additionally, ammonia volatilization and denitrification seem to be occurring. The latter could provide a self-cleaning potential to the system, if it reaches N
2
and needs further verification. Nevertheless, N inputs to the system should match crop uptake to avoid groundwater and atmospheric pollution.
The objective of this research was to determine the process of atrazine transport compared to bromide and δO18 transport in sands near Denver. Three 1.5×2×1.5-m plots were installed and allowed to ...equilibrate for 2 years before research initiation and were instrumented with 1.5×2-m zero-tension pan lysimeters installed at 1.5-m depths. Additionally, each plot was instrumented with suction lysimeters, tensiometers, time domain reflectometry (TDR) moisture probes, and thermocouples (to measure soil temperature) at 15-cm depth increments. All plots were enclosed with a raised frame (of 8-cm height) to prevent surface runoff. During the 2-year period before research began, all suction and pan lysimeters were purged monthly and were sampled for fluids immediately prior to atrazine and KBr application to obtain background concentrations. Atrazine illustrated little movement until after a significant rainfall event, which peaked concentrations at depths of about 90 to 135 cm. Both Br- and δO18 moved rapidly through the soil, probably owing to soil porosity and anion exclusion for Br-. Concentrations of atrazine exceeding 5.0 muL-1 were observed with depth (90 to 150 cm) after several months. It appears that significant rainfall events were a key factor in the movement of atrazine in the sand, which allowed the chemicals to move to greater depths and thus avoid generally found biodegradation processes.
Pulmonary surfactant is a complex mixture of lipids and proteins that forms a surface-active film at the air-water interface of alveoli capable of reducing surface tension to near 0
mN/m. The role of ...cholesterol, the major neutral lipid component of pulmonary surfactant, remains uncertain. We studied the physiological effect of cholesterol by monitoring blood oxygenation levels of surfactant-deficient rats treated or not treated with bovine lipid extract surfactant (BLES) containing zero or physiological amounts of cholesterol. Our results indicate no significant difference between BLES and BLES containing cholesterol immediately after treatment; however, during ventilation, BLES-treated animals maintained higher PaO
2 values compared to BLES
+
cholesterol-treated animals. We used a captive bubble tensiometer to show that physiological amounts of cholesterol do not have a detrimental effect on the surface activity of BLES at 37°C. The effect of cholesterol on topography and lateral organization of BLES Langmuir-Blodgett films was also investigated using atomic force microscopy. Our data indicate that cholesterol induces the formation of domains within liquid-ordered domains (L
o). We used time-of-flight-secondary ion mass spectrometry and principal component analysis to show that cholesterol is concentrated in the L
o phase, where it induces structural changes.
The thermophilic bacterium
Alcaligenes faecalis isolated from the crude oil contaminated soil of Upper Assam, India. The isolated bacterium was first screened for the ability to produce ...biosurfactant. The strain growing at 42 °C could produce higher amount of biosurfactant in medium supplemented with 2% (v/v) diesel as sole source of carbon and energy. Biochemical characterizations including FT-IR and MS studies suggested the biosurfactant to be glycolipid. Tensiometric studies revealed that the biosurfactant produced by the bacterial strain could decrease the surface tension (
σ) at air–water interface from 71.6 to 32.3 mNm
−1 after 96 h of growth on hydrocarbon and possessed a low critical micelle concentration (CMC) value of approximately 38 mgl
−1, indicating high surface activity. The culture supernatant containing the biosurfactant was found to be functionally stable at varying pH (2–12), temperature (100 and 121 °C) and salinity (1–6% NaCl, w/v) conditions. Both the culture broth and the cell free supernatant exhibited high emulsifying activity against the different hydrocarbons and the crude oil components. The increase in cell surface hydrophobicity and glycolipid production by the strain suggested the existence of biosurfactant enhanced interfacial uptake of the hydrocarbons. Moreover, the partially purified biosurfactant exhibited antimicrobial activity by inhibiting the growth of several bacterial and fungal species. The strain represented a new class of biosurfactant producers and could be a potential candidate for the production of glycolipid biosurfactant which could be useful in a variety of biotechnological and industrial processes, particularly in the oil industry.
At the end of waste disposal in 2005, a temporary mineral system was constructed to cover the waste body of the municipal landfill in Rastorf (N Germany). The aim of this study was to evaluate the ...effectiveness of this temporary cover system in limiting the infiltration of surface water into the waste body. The numerical modeling for the hydrological year 2012 was performed in FEFLOW 6.0. The required input data for modeling were achieved by laboratory measurements of the saturated hydraulic conductivity and the water retention characteristics of the mineral layers. The assumed initial and boundary conditions were based on in‐situ measurements of matrix potential and volumetric water content at three different measuring points by tensiometers, FDR sensors and observed meteorological conditions. The model was applied according to Darcy's and Richards' equations for variably saturated flow. Our results allowed assessing the components of water balance for a temporary cover system, especially water seepage into the waste body. The correlation between the measured and modeled volumetric soil water content in the layered temporary cover system was observed (R² = 0.56 to 0.90). Deviations between the measured and modeled values are superficially related to the soil´s heterogeneity. In conclusion, the measured and modeled water balance parameters indicate that the temporary coverage system remains effective in limiting the infiltration rate. However, our studies revealed that the calculated and measured water seepage exceeded the values allowable by the German regulations. Additional studies have to assess variations in the soil water characteristics caused by weather‐related wetting and drying cycles and influence of waste settlement changing the profile of slope.
RESUMO: O conhecimento dos fatores relacionados ao desenvolvimento da videira tem grande relevância, porque tem implicação na produção. Com isso, o objetivo deste trabalho foi determinar a umidade, ...utilizando a técnica de monitoramento por tensiômetria de punção digital. O experimento foi conduzido na área agrícola do Instituto Federal de Educação, Ciência e Tecnologia do Sertão Pernambucano, no campus Zona Rural situado em Petrolina – PE e em uma propriedade privada de uva de mesa. Foram realizadas nas áreas coletas de amostras indeformadas de solo, para obtenção da curva de retenção da água pelo solo. Foram instaladas três baterias de tensiômetros nas profundidades de 0-0,3 e 0,3-0,6 m na área do IF e 0-0, 2, 0,2-0,4 e 0,4-0,6 m na área propriedade privada para uva de mesa e três baterias na profundidade de 0-0,3 e 0,3-0,6 m na área do IF para uva de vinho. Concluiu-se que a umidade nas camadas superiores na uva de mesa e vinho do IF se situou sempre acima da capacidade de campo, indicando problemas de lixiviação superficial. A umidade nas camadas inferiores na uva de mesa na propriedade privada se situou próxima e ligeiramente acima da capacidade de campo, indicando problemas de lixiviação profunda. ABSTRACT: Knowledge of the factors related to the development of the vine is very important because it has implications for the production. Thus, the aim of this study was to determine the moisture, using the monitoring technique tensiometry fingerstick. The experiment was conducted in the agricultural area of the Federal Institute of Education, Science and Technology Pernambucano Hinterland on the campus located in Petrolina Rural Zone - PE and a privately owned table grape. They were carried out in the areas of collecting undisturbed soil samples to obtain the retention curve of water through the soil. Three batteries tensiometers were installed at depths of 0-0.3 and 0.3-0.6 m in the IF field and 0-0, 2, 0.2-0.4 and 0.4-0.6 m the privately owned area for table grapes and three batteries in the depth of 0-0.3 and 0.3-0.6 m in the IF area for wine grape. It was concluded that the moisture in the upper layers in the table grape and wine IF always stood above the field capacity, indicating problems of surface leaching. The moisture in the lower layers in the table grape on private property stood close and slightly above the field capacity, indicating deep leaching problems.
different Solanaceae and Erythroxylaceae species produce tropane alkaloids. These alkaloids are the starting material in the production of different pharmaceuticals. The commercial demand for tropane ...alkaloids is covered by extracting them from cultivated plants.
is cultivated under greenhouse conditions as a source of tropane alkaloids. Here we investigate the effect of different levels of water availability in the soil on the production of tropane alkaloids by
.
.
We tested four irrigation levels on the accumulation of tropane alkaloids. We analyzed the profile of tropane alkaloids using an untargeted liquid chromatography/mass spectrometry method.
Using a combination of informatics and manual interpretation of mass spectra, we generated several structure hypotheses for signals in
.
extracts that we assign as putative tropane alkaloids. Quantitation of mass spectrometry signals for our structure hypotheses across different anatomical organs allowed us to identify patterns of tropane alkaloids associated with different levels of irrigation. Furthermore, we identified anatomic partitioning of tropane alkaloid isomers with pharmaceutical applications.
Our results show that soil water availability is an effective method for maximizing the production of specific tropane alkaloids for industrial applications.
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