Measured Water Concentrations Research Articles

Drastic change of rheological behaviour of Precipitated Calcium Carbonate (PCC) formulations induced by water sorption onto mineral filler surface

The water sorption properties of Precipitated Calcium Carbonate (PCC) formulations have been studied in relation to the rheological behaviour. Uncoated mineral fillers (median diameter 0.85 μm) have been dispersed in an organic liquid used as plasticizer, a dioctylphthalate (DOP), at a concentration of 25% by weight (volume fraction of about 11%). Water sorption isotherms onto PCC in air and in the organic matrix have been constructed. Measurement of water concentration in the DOP permits a complete evaluation of water exchanges at the inorganic (mineral)/organic (plasticizer) interface. Evolutions of yield stress, storage modulus and loss modulus have been determined as functions of the water activity in the system. A drastic change of rheological properties has been observed for water activities above 0.3.

An optical-fibre water-concentration sensor using Tm3+:YAG fluorescent light

A simple optical-fibre water concentration sensor that uses absorption of the fluorescent light from the 781 nm laser-diode-pumped Tm3+:YAG crystal has been constructed. Highly sensitive and reliable measurements of water concentration are achieved by using the transmitted pumping light for the reference signal. The minimum resolution of 0.05 mass% is achieved over the water-concentration range 0 - 30 mass% using the signal wavelength of fluorescence at 1.94 µm. By suitably selecting the wavelength of the fluorescence light, water concentrations in ethanol-water and methanol-water mixtures can be measured with high sensitivity in the full range of 0 - 100 mass%.

Summertime transport of current‐use pesticides from California's Central Valley to the Sierra Nevada Mountain Range, USA

AbstractAricultural activity in California's Central Valley may be an important source of pesticides that are transported in the air to the Sierra Nevada Mountain Range, USA. Pesticides applied to this intensive crop production area may volatilize under warm temperatures typical of the valley and be transported through the atmosphere to be deposited in the cooler, higher elevation regions of the Sierra Nevada Mountains. To determine the extent of summertime atmospheric transport of pesticides to this region, high‐volume air, dry deposition, and surface water samples were collected in the Central Valley and at different elevations in California's Sequoia National Park. Results revealed that the highest residue concentrations were those of compounds with heavy summertime agricultural use. A significant drop in pesticide concentrations in both air and water samples was observed within a few 100‐m elevation from the valley; however, levels remained relatively constant between ∼500 and 2,000 m. Water concentrations from two areas above 3,000 m contained levels less than a tenth as high as those at lower elevations. Possible effects of the pesticides were estimated using measured water concentrations to calculate total exposure of three aquatic species to organophosphate insecticides. Aggregate exposure calculations showed concentrations were well below 96‐h LC50 values for rainbow trout and stonefly but concentrations may be harmful to amphipods.

Litter Composition and Ammonia Emission in Aviary Houses for Laying Hens: Part III, Water Flow to the Litter through Fresh Droppings

An observational study was carried out to investigate the level and variation of water input through fresh droppings to the litter in a tiered wire floor aviary housing system from 17 to 30 weeks of age of the hens. The mass balances of droppings (all excreta), manure on the belts and litter on the floor were modelled and these equations were used together with measurements of concentrations and newly developed measuring methods of flows and quantities of droppings, belt manure and litter. From the differences in the concentration of ash, nitrogen, phosphorus and potassium between droppings, belt manure and litter, it was concluded that the transport of litter between the feathers of the hens to the belts was negligible. The relative amount of excreta deposited in the litter by the hens yielded a peak of about 50% around 22 weeks of age. Thereafter, the flow of droppings to the litter decreased to a stabilized level of about 10%. The flow of water to the litter through the droppings showed the same pattern, with a peak of about 45 g/d per hen and a stabilized level of about 7 g/d per hen. The actual peak might have been 10–30 g/d per hen higher, because measured water concentrations of the droppings were 40–90 g/kg lower than the water concentration of freshly excreted droppings. It was hypothesized that the peak in the water flow to the litter was caused by the changing behaviour of the hens, as indicated by the relative number of measured weights of the hens on scales in the litter area and on a feeding tier. Hens spent less time in the litter area for scratching and dust bathing after 20 weeks of age, presumably because they spent more time in the nests for laying eggs and on the tiers for eating and drinking.

SUMMERTIME TRANSPORT OF CURRENT-USE PESTICIDES FROM CALIFORNIA'S CENTRAL VALLEY TO THE SIERRA NEVADA MOUNTAIN RANGE, USA

Aricultural activity in California's Central Valley may be an important source of pesticides that are transported in the air to the Sierra Nevada Mountain Range, USA. Pesticides applied to this intensive crop production area may volatilize under warm temperatures typical of the valley and be transported through the atmosphere to be deposited in the cooler, higher elevation regions of the Sierra Nevada Mountains. To determine the extent of summertime atmospheric transport of pesticides to this region, high-volume air, dry deposition, and surface water samples were collected in the Central Valley and at different elevations in California's Sequoia National Park. Results revealed that the highest residue concentrations were those of compounds with heavy summertime agricultural use. A significant drop in pesticide concentrations in both air and water samples was observed within a few 100-m elevation from the valley; however, levels remained relatively constant between ∼500 and 2,000 m. Water concentrations from two areas above 3,000 m contained levels less than a tenth as high as those at lower elevations. Possible effects of the pesticides were estimated using measured water concentrations to calculate total exposure of three aquatic species to organophosphate insecticides. Aggregate exposure calculations showed concentrations were well below 96-h LC50 values for rainbow trout and stonefly but concentrations may be harmful to amphipods.

Analysis of ammonia and aerosol concentrations and deposition near the free troposphere at Mt. Mitchell, NC, U.S.A.

Measurements of airborne (gaseous and aerosol), cloud water, and precipitation concentrations of ammonia (NH 3) and ammonium (NH + 4) compounds were made at Mt. Mitchell State Park (Mt. Gibbs, ∼2006 m MSL), North Carolina. Measurements were made from May to September during 1988 and 1989. An annular denuder system was used to determine gaseous NH 3 and particulate NH + 4 and nitrate (NO - 3) compounds. Measurements of NH + 4 in cloud and rain water samples were made during the same time period. Mean concentrations of gaseous NH 3 were 0.62 μg m -3 for 1988 and 1.47 μg m -3 for 1989. Mean concentrations of fine particulate NH + 4 were 1.24 μg m -3 for 1988 and 0.89 μg m -3 for 1989. The NH + 4 concentrations in the cloud water were 214 and 147 μeq ℓ -1 for the 1988 and 1989 field seasons, respectively. The concentrations of NH + 4 in precipitation were quite low compared to cloud ionic values in both 1988 and 1989 at 14 and 15 μeq ℓ -1, respectively. The estimated mean total deposition of NH + 4 over the sampling period (5 months) of 1988 and 1989 was about 0.38 and 0.67 g N m -2 season -1, respectively. Cloud water interception contributed more nitrogen (∼70%) to the total deposition than combined wet (∼15%) and dry (∼15%) deposition.

Effects of Lindane on the Planktonic Community in Freshwater Microcosms

Effects of lindane on natural planktonic communities were investigated in aquatic indoor microcosms. Lindane was dosed to eight 300-liter microcosms for 2 weeks, and effects and recovery processes were monitored over 12 weeks. Mean measured water concentrations of lindane during the exposure period were 3, 6, 13, 27, 55, 102, 230, and 455 μg/liter. Zooplankton was severely affected by lindane. The most sensitive organisms were nauplii of copepodes which were affected at all treatment levels ≥6 μg/liter during exposure (Days 2–14). Recovery of nauplii abundance was concentration-dependent at concentrations ≤55 μg/liter lindane, whereas at concentrations ≥102 μg/liter recovery was negligible.Cladoceraabundance decreased during exposure to ≥102 μg/liter lindane and did not recover to original levels until the end of the study. For phytoplankton, decreased population densities ofChlorophyceaeand microalgae (<5 μm) were observed at lindane concentrations ≤55 μg/liter, where zooplankton was only temporarily affected. At higher lindane concentrations (≥102 μg/liter) effects on phytoplankton were not clear, as also increases in abundances were observed, probably as a consequence of minimized grazing pressure, due to high zooplankton mortality. Comparison of these results with data obtained in complex outdoor systems demonstrates the practicability and sensitivity of indoor microcosms and emphasizes the importance of long-term testing and assessment of recovery processes for prediction of environmental effects.

Measurements of OH and H2O for reacting flow in a supersonic combusting ramjet combustor

Mixing and combusting high-enthalpy flows, similar to those encountered in supersonic combusting ramjet engines, were investigated using a shock tunnel to produce the flow in conjunction with nonintrusive optical diagnostics that monitored the performance of two injector configurations. The shock tunnel was configured to produce Mach 3 flow and stagnation enthalpies corresponding to flight equivalent Mach numbers between 7— 11. A pulsed hydrogen injection capability and interchangeable injector blocks provided a means of examining high-speed, high-enthalpy reacting flows. Planar laser induced fluorescence of OH radicals in the near-injector region produced images that show the combusting and mixing zones for the reacting flow. Line-of-sight exit plane measurements of water concentration and temperature were used to provide a unique method of monitoring exit plane products. Near-injector mixing dynamics and exit plane compositions were compared for wall jet and axial injection systems. In addition, exit plane measurements indicated that a quasi-steady-state condition was achieved during the 1- to 2-ms test times.

Monitoring Deposition of Nitrogen-Containing Compounds in a High-Elevation Forest Canopy

Measurements of airborne (gaseous and aerosol), cloud water, and precipitation concentrations of nitrogen compounds were made at Mt. Mitchell State Park (Mt. Gibbs, ~2006 m MSL), North Carolina, during May through September of 1988 and 1989, An annular denuder system was used to ascertain gaseous (nitric acid, nitrous acid, and ammonia) and particulate (nitrate and ammonium) nitrogen species, and a chemiluminescence nitrogen oxides analyzer was used to measure nitric oxide and nitrogen dioxide. Measurements of NO3 − and NH4 + ions in cloud and rain water samples were made during the same time period. Mean concentrations of gaseous nitric acid, nitrous acid, and ammonia were 1.14 μg/m3, 0.3 μg/m3, and 0.62 μg/m3 for 1988, and 1.40 μg/m3,0.3 μg/m3, and 1.47 μg/m3 for 1989, respectively. Fine particulate nitrate and ammonium ranged from 0.02 to 0.21 μg/m3 and 0.01 to 4.72 μg/m3 for 1988, and 0.1 to 0.78 μg/m3 and 0.24 to 2.32 μg/m3 for 1989, respectively. The fine aerosol fraction was dominated by ammonium sulfate particles. Mean concentrations of nitrate and ammonium ions in cloud water samples were 238 and 214 μmol/l in 1988, and 135 and 147 μmol/l in 1989, respectively. Similarly, the concentrations of NO3 and NH4 + in precipitation were 26.4 and 14.0 μmol/l in 1988, and 16.6 and 15.2 μmol/l in 1989, respectively. The mean total nitrogen deposition due to wet, dry, and cloud deposition processes was estimated as ~30 and ~40 kg N/ha/year (i.e., ~10 and ~13 kg N/ha/growing season) for 1988 and 1989. Based on an analytical analysis, deposition to the forest canopy due to cloud interception, precipitation, and dry deposition processes was found to contribute ~60, ~20, and ~20 percent, respectively, of the total nitrogen deposition.

The effect of positive end-expiratory pressure on regional pulmonary perfusion during acute lung injury

Purpose: To determine whether positive end-expiratory pressure (PEEP) would change the altered regional pulmonary perfusion pattern caused by oleic acid (OA)-induced acute lung injury was the aim of this study. Our hypothesis was that fixed intravascular obstruction would not be affected by PEEP, leaving the perfusion pattern unchanged if this was the principal cause of perfusion redistribution after lung injury. Methods: Regional measurements of pulmonary perfusion and lung water concentration (LWC) were obtained both before and after lung injury and before and after PEEP (10 cm H 2O) with the nuclear medicine imaging technique of positron emission tomography after injections of H 2 15O in 7 supine anesthetized dogs. Four animals were also treated with meclofenamate to enhance perfusion redistribution after acute lung injury. Results: The application of PEEP before lung injury did not significantly affect the regional perfusion pattern. After administration of OA, LWC increased and fractional flow (without PEEP) decreased to the most edematous lung regions, consistent with perfusion redistribution. With the reapplication of PEEP, the perfusion pattern reverted toward the baseline pattern. The magnitude of this effect was roughly proportional to the effect of PEEP on regional inflation ( r = .53), as evidenced by changes in LWC. Conclusions: The reversibility with PEEP of the perfusion pattern caused by acute lung injury suggests that fixed intravascular obstruction is not the principal determinant of perfusion redistribution after OA-induced injury.

Adipose tissue metabolism in humans determined by vein catheterization and microdialysis techniques

A technique for catheterization of a vein draining abdominal subcutaneous tissue and a microdialysis technique that allows measurements of intercellular water concentrations in adipose tissue in humans have recently been described. In the present study, we compare the two techniques during an oral glucose load. In addition a technique using microdialysis for measurement of tissue oxygen and carbon dioxide tensions is described. Microdialysis and vein catheterization were performed in the same region on the abdomen, and the subcutaneous adipose tissue blood flow was measured by the local 133Xe washout method. The results show that subcutaneous adipose tissue gas tensions are on level with gas tensions measured in abdominal venous blood. Comparison of metabolite concentrations measured in the venous blood and venous blood concentrations calculated from microdialysis data shows that there is good agreement between the concentrations obtained by the two techniques with respect to glucose and glycerol, whereas lactate concentrations are very different. With regard to substrate fluxes calculated by Fick's principle, the catheterization technique is probably the most reliable, considering the numerous assumptions on which calculations of venous concentrations from microdialysis data are based. Advantages and disadvantages of the two techniques are discussed.

Thromboxane receptor stimulation/inhibition and perfusion redistribution after acute lung injury.

Perfusion redistribution (PR) after acute oleic acid (OA) lung injury may be the result of changes in the tissue concentration ratio of thromboxane (Tx) and prostacyclin (A. H. Stephenson et al. J. Appl. Physiol. 73: 2126-2134, 1992). We tested this hypothesis by determining whether the Tx mimetic U-46619 would mimic PR caused by cyclooxygenase inhibition with meclofenamate and whether the Tx receptor antagonist ONO-3708 would inhibit PR even in the presence of meclofenamate. Measurements of regional pulmonary blood flow (PBF) and lung water concentration were made with the nuclear medicine imaging technique of positron emission tomography. Measurements were made at baseline and 2 h after OA. At baseline, the spatial distribution of PBF was similar in all experimental groups. Two hours after OA, fractional PBF was reduced to the edematous lung in all groups given OA, but the magnitude of change was greater in those groups receiving meclofenamate or U-46619 compared with the change in the group given OA only. Thus, although the Tx mimetic produced the same amount of PR as meclofenamate, Tx inhibition did not prevent PR after meclofenamate. Therefore, the ratio of Tx to prostacyclin per se is not the critical determinant of PR.

Spatial Variability of Physical Parameters and Processes in Two Field Soils

Natural field systems exhibit a large degree of soil heterogeneity which affects the movement of water and solutes and thus leads to highly varying observations of water content and solute concentration. To investigate this problem comprehensive field investigation programs were carried out at two field sites in Denmark representing two different soil types, a coarse sand and a sandy loam, respectively. The field investigations included collection of soil samples for analysis of textural composition, retention, and hydraulic conductivity, measurements of water content and suction, and measurements of radioactive tracer concentration, all carried out at a number of positions within the two field sites. Models for one-dimensional vertical unsaturated flow and solute transport were applied to the two field sites, and the simulation results were compared to field measurements of water content, suction and solute concentration. This paper describes results from model simulations in individual soil profiles, while the variability issues at field scale are described in the two accompanying papers. The modelling approach was based on numerical solutions to Richards' equation for water flow and the convection-dispersion equation (CDE) for solute transport. The model results from the coarse sand field site compared relatively well to measurements of water content, suction, and concentration except for the upper soil layer (∼ 10 cm depth) where the measured water contents appeared to be somewhat uncertain. Due to the neglecting of hysteresis and macropore flow (by-pass) in the model the measured retention curves (drainage based) and the hydraulic conductivity functions at the sandy loam field site had to he modified empirically through the calibration procedure in order to match the measurements.

A quantitative correlation of extravascular lung water accumulation with vascular permeability and hydrostatic pressure measurements: a positron emission tomography study

In 11 supine dogs, we related regional lung water concentration (rLWC) measurements made with positron emission tomography (PET) after canine oleic acid (OA)-induced acute lung injury to extravascular lung water measurements by the thermal-green dye indicator dilution technique (EVLW-TGD), and to measurements of vascular permeability (also by PET) and hydrostatic pressure. The rLWC measurements correlated well with EVLW-TGD (R 2 = 97%). Changes in LWC did not correlate with either the pulmonary wedge pressure or PET measurements of protein leak (as an index of vascular permeability), but were related when both variables were considered together (R 2 = 73%). Lung water concentration increased significantly 60 minutes after OA, primarily in dorsal, gravity-dependent lung regions, with a small, but statistically significant, change over the next 75 minutes. These data suggest that PET measurements of LWC or EVLW on one tomography slice can be representative of changes in EVLW in the lung as a whole after diffuse lung injury. Furthermore, the magnitude of edema accumulation after acute lung injury can be accurately predicted by quantitative measurements of hydrostatic pressure and of protein leak using PET.

Long-term behavior of municipal solid waste landfills

A method is presented to predict the long-term behavior of element concentrations (non-metals and metals) in the leachate of a municipal solid waste (MSW) landfill. It is based on water flux and concentration measurements in leachates over one year, analysis of drilled cores from MSW landfills and leaching experiments with these samples. A mathematical model is developed to predict the further evolution of annual flux-weighted mean element concentrations in leachates after the “intensive reactor phase”, i.e. after the gas production has dropped to a very low level. The results show that the organic components are the most important substances to control until the leachate is compatible with the environment. This state of low emissions, the so-called “final storage quality”, will take many centuries to be achieved in a moderate climate.

On-stream measurement of heavy water concentration by intermediate neutron moderation

A method of measuring heavy water concentration is described based on intermediate neutron moderation. With a 1.6 μg252Cf neutron source and a BF3 proportional counter, for 500 ml samples, accuracies of the measurements are within ±0.02 mol% in the concentration range of 0∼100 mol% with 2∼10 minute counting. To evaluate the practical effectiveness of the method, a model apparatus was built for routine use in laboratory and on-stream measurements. It was successfully applied to observe the substitution process between light water and heavy water in an ion exchange resin tower at a nuclear power station.

Long-Term Behavior of Municipal Solid Waste Landfills

A method is presented to predict the long-term behavior of element concentrations (non-metals and metals) in the leachate of a municipal solid waste (MSW) landfill. It is based on water flux and concentration measurements in leachates over one year, analysis of drilled cores from MSW landfills and leaching experiments with these samples. A mathematical model is developed to predict the further evolution of annual flux-weighted mean element concentrations in leachates after the "intensive reactor phase", i.e. after the gas production has dropped to a very low level. The results show that the organic components are the most important substances to control until the leachate is compatible with the environment. This state of low emissions, the so-called "final storage quality", will take many centuries to be achieved in a moderate climate.

Glucocorticosteroid treatment of vasogenic oedema.

The components of vasogenic oedema associated with brain tumours were investigated in human biopsy material sampled from tumour and peritumoural tissue intraoperatively. Sixty patients with glioblastomas, gliomas, meningiomas and metastases, which had been treated with dexamethasone prior to surgery were employed for tissue measurements of water, electrolyte, haemoglobin, serum protein and dexamethasone concentrations. The quantification of serum proteins was achieved with the method described by Bodsch et al. Accordingly, serum proteins in the brain tissue and the blood were determined with 125J labelled antihuman antibody. Taking into account brain haematocrit and blood-volume, quantitative measurements of the so-called oedema proteins as a measure of tumour oedema were performed. With the exception of metastases positive correlations were obtained between water and both serum proteins and sodium contents in tumours and peritumoural tissue. The serum protein content varied considerably being high in glioblastomas and low in peritumoural tissue surrounding metastases. However water and serum protein contents decreased with increasing dexamethasone concentrations in glioblastomas, while this effect was virtually absent in gliomas and meningiomas. Our results suggest a previously unknown selectivity among tumour types for the reduction of water content and serum proteins in corticosteroid treated oedematous tissue.

Factors responsible for the retention of fluid in human tumor edema and the effect of dexamethasone.

The components of vasogenic edema associated with brain tumors were investigated in human biopsy material sampled from tumor and peritumoral tissue during neurosurgical operations. Tissue from 60 patients with glioblastomas, gliomas, meningiomas, and metastases who had been treated with dexamethasone prior to surgery was used for measurement of water, electrolyte, hemoglobin, serum protein, and dexamethasone concentrations. In all samples except metastases, positive correlations were obtained between water content and both serum protein levels and sodium content in tumors and peritumoral edema, suggesting that these components simultaneously determine forces for extravasation of plasma-derived edema fluid. However, the mean serum protein content varied considerably, being high in glioblastomas (16 mg/ml) and low in peritumoral edema surrounding metastases (4 mg/ml). The mean cerebral blood volume in all samples, as calculated from the tissue hemoglobin content, was 2.5 ml/100 gm wet weight in tumor tissue and 1.6 to 2.0 ml/100 gm wet weight in peritumoral tissue. Sodium concentrations were not significantly different among the tumor types. Both water and serum protein content decreased with increasing dexamethasone concentrations in glioblastomas, while this effect was virtually absent in gliomas and meningiomas. A therapeutic threshold of dexamethasone at 500 mg/gm wet weight was obtained for tumoral and peritumoral tissue of glioblastomas and was effective in a dose-dependent manner as long as the water content and the serum protein concentration remained below 6 ml/gm dry weight and 30 mg/gm dry weight, respectively. These results suggest a previously unknown selectivity among tumor types for the reduction of both water content and serum proteins in corticosteroid-treated edematous tissue.

Two-phase liquid hydrocarbon-hydrate equilibrium for ethane and propane

An experimental method was generated and proven for the measurement of the water content of a liquid hydrocarbon which is in equilibrium only with hydrates. The method was used to determine the water content of both liquid propane and liquid ethane when hydrates were present, without the presence of a free water phase. The dielectric constant apparatus enabled the water concentration measurement of the hydrocarbon liquid without sample withdrawal. The temperature range was 246-276 K with pressures of 0.77 MPA (propane) and 3.5 MPa (ethane), and the water concentrations in the hydrocarbon were from 16 to 176 ppm (mol).