Increase In Volume Of Water Research Articles

Evaluation of Electricity Product by Increasing Water Volume During Freezing

Electricity production process by the use of water expansion during freezing. By use of a closed volume such as piston and cylinder. The volume increase of ice could be transformed linearly and cause piston displacement, by the use of cold resource and heat resources. This process is possible where boarding temperature difference is high and water temperatures reach below 0°C this method uses a cylinder and piston which passes a complete cycle. The piston is driven upward due to the ice expansion and when the ice is melting it returns to its initial position. All rights reserved.

Pharmaco-thermodynamics of deuterium-induced oedema in living rat brain via 1H2O MRI: implications for boron neutron capture therapy of malignant brain tumours**All three authors have contributed equally to this work.

In addition to its common usage as a tracer in metabolic and physiological studies, deuterium possesses anti-tumoural activity and confers protection against γ-irradiation. A more recent interest in deuterium emanates from the search for alternatives capable of improving neutron penetrance whilst reducing healthy tissue radiation dose deposition in boron neutron capture therapy of malignant brain tumours. Despite this potential clinical application, deuterium induces brain oedema, which is detrimental to neutron capture therapy. In this study, five adult male rats were titrated with deuterated drinking water while brain oedema was monitored via water proton magnetic resonance imaging. This report concludes that deuterium, as well as deuterium-induced brain oedema, possesses a uniform brain bio-distribution. At a steady-state blood fluid deuteration value of 16%, when the deuterium isotope fraction in drinking water was 25%, a mean oedematous volume change of 9 ± 2% (p-value <0.001) was observed in the rat brain—this may account for neurological and behavioural abnormalities found in mammals drinking highly deuterated water. In addition to characterizing the pharmaco-thermodynamics of deuterium-induced oedema, this report also estimates the impact of oedema on thermal neutron enhancement and effective dose reduction factors using simple linear transport calculations. While body fluid deuteration enhances thermal neutron flux penetrance and reduces dose deposition, oedema has the opposite effect because it increases the volume of interest, e.g., the brain volume. Thermal neutron enhancement and effective dose reduction factors could be reduced by as much as ∼10% in the presence of a 9% water volume increase (oedema).

Changes in river discharge structure and regime in mining-industrial-urban areas

In mining-industrial-urban areas, the variability of river discharge is regulated, directly or indirectly, by human economic activity. This results from the presence of “alien” water, which often comes from outside the catchment area, is discharged into the river network. This water includes industrial and municipal wastewater and deep-drainage mine water. Simultaneously, as a result of water intake and water infiltration into dry ground (due to mining), the volume of river discharge decreases. Such changeable conditions of water alimentation and drainage are typical of many regions of Europe. Detailed investigations of the range and directions of changes in river structure and regime were carried out for the area of Upper Silesian Industrial Region (USIR) of Poland. The results were compared with the results of investigations carried out in the Ruhr Basin of Germany and the Donetsk Basin of the Ukraine and Russia. The investigations showed that, in some cases, prolonged, multifunctional economic activity of a man has effectively eliminated of the influence of natural hydrometeorological conditions on river discharge. Wastewater and mine water which has contributed to river flow is only slightly variable in the annual cycle and it causes an increase of water volume and a discharge smoothing. Sewage effluent and mine wastewater also change the structure of river runoff because their contribution to the runoff sometimes exceeds 90% of its volume.

Effect of Water Regime and Nitrogen Fertilisation on Growth Dynamics, Water Status and Yield of Burley Tobacco (Nicotianatabacum L.)

Abstract The results of a two-year research project into burley tobacco are reported and discussed. Three irrigation levels (40, 80 and 120% restitution of evapotranspiration (ET)) were factorially combined with four levels of nitrogen fertilisation (0, 80, 160 and 240 kg ha). Leaf area, leaf and stem dry matter and root development were measured. We monitored the water status of the 0-90 cm soil layer, the plants and stomatal resistance. Relations were also studied between leaf turgor pressure and plant growth, between the irrigation regime and plant water status, and between root and shoot development. Finally, water use efficiency (WUE) and quality and quantity of cured leaves yields were evaluated. Nitrogen fertilisation did not affect plant water status, although it promoted plant growth, both in terms of leaf area and leaf and stem dry matter, and induced a yield increase in quantity and quality. Our trial showed little interaction between nitrogen fertilization level and water regime. Under such agronomic condition, the margins for increasing plant growth with nitrogen fertilization are limited, which is why application of nitrogen rates in excess of 160 kg haappear inadvisable. The difference in irrigation volumes led to a different soil water content which affected plant water status, stomatal functioning, plant growth, both in the roots and shoots, yield and quality of the cured leaves. The latter did not vary with the increase in water volume, while yield increased. Water use efficiency increased as the irrigation volume decreased and varied during the cropping cycle, increasing until early bloom, then decreasing. Relations between leaf turgor pressure and plant growth highlighted the different response of plants subjected to water stress compared with non-stressed plants.

Deposition and redistribution of fungicides applied by air and chemigation for control of late blight in commercial potato fields

The fungicides metiram, mancozeb, metiram + triphenyltin hydroxide, propamocarb hydrochloride + chlorothalonil, dimethomorph + mancozeb, cymoxanil + mancozeb, and chlorothalonil were applied by aircraft and through center-pivot irrigation systems (chemigation) to replicated plots in commercial fields of ‘Russet Burbank’ potato. Fungicide deposition and redistribution were indirectly determined by inoculation of excised leaves withPhytophthora infestans and directly by chlorothalonil residue analysis from upper, middle, and lower crop canopies. The effectiveness of two surfactants added with fungicide and applied by aircraft, an increased water volume rate used by aircraft, and a reduced water volume used with chemigation was also determined. The addition of synthetic latex and siliconepolyether surfactants did not increase efficacy of metiram or mancozeb in controlling late blight when applied by aircraft. The protectant fungicides metiram, mancozeb, and chlorothalonil were not significantly different from dimethomorph + mancozeb, cymoxanil + mancozeb, and propamocarb hydrochloride + chlorothalonil in late blight control when applied by aircraft. However, cymoxanil + mancozeb had limited efficacy when applied by chemigation. Fungicide deposition through the canopy differed when air applications were made before or after canopy closure (row closure). Fungicides applied by aircraft prior to row closure protected the entire canopy; whereas, fungicide application after row closure initially protected the top and middle canopies, and subsequent applications and redistribution of the fungicides were needed for adequate protection throughout the canopy. The fungicides and fungicide mixtures tested were evenly deposited throughout the potato canopy with each chemigation application. Severity of late blight did not differ on leaves treated with mancozeb or chlorothalonil applied by aircraft at water volumes of 47 L/ha and 94 I/ha and then inoculated withP. infestans, nor did severity of late blight differ on inoculated leaves previously treated with chlorothalonil by chemigation at water volumes of 15,145 and 50, 571 L/ha.

Effects of temperature and body weight on ventilation volume of common carp (Cyprinus carpio L.)

Background. Ventilation volume is a parameter used mainly for determining oxygen consumption of fish. The aim of the present work was to determine the ventilation volume of carp, under conditions of pure, aerated water. Material and methods. Stroke volume and breathing rate of carp representing three size groups (258.7 ± 40.1 g, 449.3 ± 39.6 g, and 663.2 ± 32.3 g) were studied within the temperature range of 10–25°C. Results. At 10°C the stroke volume of carp weighing 200–300 g was on average 2.25 ± 0.63 ml per 1 breath. This parameter in fish weighing 400–500 g was 2.70 ± 0.12 ml per 1 breath, while in fish attaining 600–700 g it amounted to 3.22 ± 0.41 ml per 1 breath. The breathing rate of all size groups ranged from 46.2 to 47.4 ± 8.51 cycles per min. A statistically significant increase of the stroke volume was recorded in all size groups at 15°C. At 20°C the increased stroke volume was accompanied by accelerated breathing rate. The temperature increase from 20 to 25°C did not cause any further increase of either breathing rate or stroke volume. Conclusion. The temperature-related regulation of the ventilation volume in carp is a two-step process. At 10–15°C the increased water volume pumped through the gills was achieved by an increased breathing depth (stroke volume). A further increase of the ventilation volume at 15–25°C resulted from acceleration of the breathing rate.

Water acquisition and partitioning in Drosophila melanogaster: effects of selection for desiccation-resistance.

We examined physiological features related to water balance in five replicate populations of Drosophila melanogaster that have undergone selection for enhanced resistance to desiccation (D populations) and in five replicate control (C) populations. Adult D flies contain 34 % more water than the control flies. We examined two hypotheses for increased water acquisition in the D flies: (i) that they accumulate more water early in development and (ii) that they have a reduced post-eclosion diuretic water loss. We found no evidence of differential water or dry mass acquisition between the C and D populations prior to adulthood. We also found no evidence of differential post-eclosion diuresis, i.e. both C and D groups showed insignificant changes in water volume in the 4 h period immediately after eclosion. In addition, we quantified water content in the intra- and extracellular compartments of the C and D populations and were able to identify the hemolymph as the primary storage site of the 'extra' water carried by the desiccation-resistant flies. We estimated that 68 % of the increased water volume observed in the D flies was contained in the hemolymph. Desiccation-resistance was strongly correlated with hemolymph volume and only weakly with intracellular water volume. Survival during desiccation was also strongly related to the carbohydrate content of the D flies. It has been presumed that the D flies accumulate carbohydrate primarily as intracellular glycogen, which would result in a significant increase in intracellular water volume. We found that carbohydrate content was weakly correlated with intracellular water volume and more strongly with hemolymph volume. The carbohydrate pool in the D flies may, therefore, be contained in the extracellular compartment as well as in cells. These results are suggestive of the importance of modifications in hemolymph volume and hemolymph solute concentrations in the evolution of enhanced desiccation-tolerance in populations of Drosophila melanogaster.

Operational restoration of the Pen Branch bottomland hardwood and swamp wetlands — the research setting

The Savannah River swamp, a 3020 ha forested wetland on the floodplain of the Savannah River, USA is located on the Department of Energy's Savannah River site (SRS) near Aiken, SC. Historically, the swamp consisted of approximately 50% bald cypress–water tupelo ( Taxodium distichum– Nyssa aquatica) stands, 40% mixed bottomland hardwood stands, and 10% shrub, marsh, and open water. Creek corridors were typical of southeastern bottomland hardwood forests. Hydrology was controlled by flooding of the Savannah River and by flow from four creeks that drain into the swamp prior to flow into the Savannah River. Upstream dams have caused some alteration of the water levels and timing of flooding within the floodplain. Major impacts to the swamp hydrology occurred with the completion of the production reactors and one coal-fired powerhouse at the SRS in the early 1950s. Flow in one of the tributaries, Pen Branch, was typically 0.3 m 3 s −1 (10–20 cfs) prior to reactor pumping and 11.0 m 3 s −1 (400 cfs) during pumping from 1954 to 1988. Sustained increases in water volume resulted in overflow of the original stream banks, the creation of additional floodplains, considerable erosion of the original stream corridor, and deposition of a deep silt layer on the newly formed delta. Heated water was discharged directly into Pen Branch and water temperature in the stream often exceeded 65°C. The nearly continuous flooding of the swamp, the thermal load of the water, and the heavy silting resulted in complete mortality of the original vegetation in large areas of the floodplain. In the years since pumping was reduced, no volunteer seedlings of heavy-seeded hardwoods or cypress have been found in the floodplain corridor. Research was conducted to determine methods to reintroduce tree species characteristic of more mature forested wetlands. Species composition and selection were altered based on the current and expected hydrological regimes that the reforestation areas will be experiencing.

Larval period and molting in the Japanese spiny lobster Panulirus japonicus under laboratory conditions

SUMMARY: A total of 325 pueruli of the spiny lobster Panulirus japonicus was successfully reared in the laboratory at Minami-Iku Station of Japan Sea-Farming Association, Shizuoka, Japan, during 1989–1997. Of these pueruli, 136 individuals metamorphosed into the first juvenile stage. The duration of the phyllosoma stage ranged from 231 to 417 days (mean 319.4 days), and it has a tendency to extend as the increase of water volume in the rearing tanks. The number of molting in the phyllosoma stage was 20–31. The body length of the last-stage phyllosoma ranged from 27.9 to 34.2 mm and the duration of the last stage was 11–26 days. The carapace length of the puerulus stage was 6.0–8.0 mm and the duration was 9–26 days. The present data and those of previous studies suggest that the body size and the duration of phyllosoma stage in captivity are affected by environment as in the field. The duration of the puerulus stage is considered to be controlled basically by water temperature and nutritional conditions in the phyllosoma.

Environmental and biological factors influence the relationship between a predator fish, Gambusia holbrooki , and its main prey in rice fields of the Lower Mondego River Valley (Portugal)

We studied the relationships between a predator fish, Gambusia holbrooki, and its main food prey, within the content of a rice field food web. The influence of some environmental and biological factors on these trophic interactions, in combination with existent quantitative information, allowed us to evaluate the ecological viability of using a non-ionic surfactant, Genapol OXD-080, to control a plague caused by crayfish (Procambarus clarkii) populations in the rice fields. In the Lower Mondego River Valley, Portugal, G. holbrooki is abundant in rice fields. It feeds mainly on copepods, cladocerans and rotifers. Surface insects, such as aphids, collembolans, adult (imago) chironomids and other dipterans, are additional food. Large G. holbrooki consumed greater amounts of cladocerans and adult chironomids than other smaller size groups, while small fish prefered rotifers. Gravid females ate copepods, cladocerans, and adult chironomids and other dipterans in significantly greater amounts than immatures, males, and non-gravid females. Non-gravid females ate collembolans in significantly greater quantities than any other fish group. The population density of copepods, cladocerans, adult chironomids, and other dipterans, the area covered by aquatic vegetation, and water temperature all had significant effects on the total number of prey caught by G. holbrooki. In contrast, a negative correlation was found with rotifers, collembolans, aphids in higher densities, and of increased water volume, dissolved oxygen and pH. G. holbrooki holds a key intermediate position in the rice field food chain, feeding in large amounts of aquatic invertebrates and being eaten, in turn, by piscivores. With regard to the toxicity of Genapol OXD-080 on non-target organisms, LC50 values for G. holbrooki and some of its main prey were several times lower than the concentration necessary to decrease the activity of crayfish populations in the rice fields. Thus, Genapol OXD-080 could potentially cause greater damage to the local populations of non-target species and should not be used without taking precautions not to contaminate other important biological reservoirs, such as the rice field irrigation channels.

Hydrochemical State of the Kuibyshev Reservoir

An attempt has been made to ascertain the structure of water masses of the Kuibyshev reservoir, one of the largest in Europe, using mathematical techniques and results of long-term observations (1958-84) of the hydrochemical regime (a gaseous regime, biogenic and organic substances) in the reservoir. The principal features of the structure obtained appeared to be its well-defined two-vector pattern describing two directions of changing water masses along the former bed of the Volga river, as well as the stability of this system in time. Regionalization of the reservoir's water area has yielded five zones differing in water quality. The long-term observationshave enabled the establishment of a certain trend in biogenic concentrations showing their increase since the end of the 1970s and continuing at the present time. This is believed to result primarily from increasing water volume in the Volga river and accelerating anthropogenic pressure upon the reservoir.

Standardization of clinical criteria required for use of the 12.5 millimeter barium tablet in evaluating esophageal lumenal patency

Background: Although the barium tablet is commonly used in evaluating lumenal patency of the esophagus, the conditions under which the tablet should traverse a normal esophagus have not been established. This study was designed to standardize the minimal criteria required to ensure successful esophageal transit of a commercially available barium tablet in normal subjects. Methods: Each of 20 volunteers swallowed a standard 12.5 mm barium tablet under fluoroscopy in the supine, 45° incline, and upright positions. Tablets were swallowed dry and with fixed volumes of water (15, 30, 60, and 100 cc). Success of pill passage into the stomach was determined by fluoroscopy at 20, 40, 60, and 90 seconds. Results: Successful pill passage correlated significantly with position (passing 17.0%, 66.5%, and 69.7% in the supine, incline, and upright position, respectively; p < .0001) and volume of water ingested (passing 9.1% when swallowing dry, and 38.7%, 55.8%, 70.0%, and 81.6% with 15, 30, 60, and 100 cc of water, respectively; p ≤ .004). Duration of time beyond 20 seconds failed to affect rate of pill passage. Ingestion of 60 cc of water in the incline position was associated with a 95% pill passage, a rate significantly greater than any position at lower volumes. Increasing water volume above 60 cc or assuming the upright position did not increase this passage rate further. Conclusions: The minimum criteria required to optimize successful transit of a 12.5 mm barium tablet through a normal esophagus is to perform the test in the 45° incline position with 60 cc of water for a period of 20 seconds. Failure of the pill to pass under these conditions may suggest a true structural abnormality of the esophagus. (Gastrointest Endosc 1996;44:181-4.)

Passages: Three Poems at Thorn Portal

Passages: Three Poems at Thorn Portal

Influence of different sized fractions of a fly ash on workability of mortars

The study of fly ash as a replacement to mortar workability using a flow table is presented. Flow table spread (FTS) values were measured and correlations among fly ash replacing percentages, water volumes and granulometric distributions of fly ashes have been established. Linear relationships between FTS values and water volumes were obtained in the 200–225 mL water range (0.5 water/cement+fly ash ratio, 3.0 natural sand/cement + fly ash ratio). An increase of water volume implies greater FTS values. Original fly ash was separated in four fractions with different granulometric distributions. FTS values increase as do specific surface, and FTS values decrease as mean diameter of fly ash increase. For the finest fraction, the lubricant effect was counteracted by water adsorption on fly ash particles surfaces. The shape distribution curves of fly ashes (original and their fractios) has an important influence on workability.

Atrazine Movement in Soil Columns as Influenced by Starch-Encapsulation and Acrylic Polymer Additives

Alternative herbicide formulations may have the potential to reduce atrazine leaching. This study was conducted to determine if starch-encapsulation produced using an extrusion process or several acrylic polymer additives reduced atrazine leaching in soil columns packed with Plainfield sand (98% sand and 0.7% organic matter). Three watering regimes were evaluated to determine the effects of water volume and rate of application on atrazine movement When 7.6 cm of water (0.44-pore volumes) was applied over 2 h, polymer treatments reduced atrazine movement from the soil surface by 9 to 21% compared to atrazine without the additives. With increased water volume and time, the effectiveness of several polymer treatments diminished. Acrysol ASE-108 and G110 polymers (mixed with atrazine at a 1:1 ratio) most effectively reduced atrazine leaching over all watering regimes. Starch encapsulation was more effective than any polymer additive in retarding atrazine movement Increasing the water volume from 7.6 to 15.2 cm (0.88-pore volumes) did not increase leaching of starch-encapsulated atrazine. Ninety-nine percent of the starch-encapsulated atrazine was retained in the top 5 cm of the column compared to only 18 and 13% of the dry flowable formulation (DF) when 0.44- and 0.88-pore volumes of water were applied over 2 and 4 h, respectively. When 0.88-pore volumes of water were applied over 12 d, 81% of the starch-encapsulated atrazine was retained in the upper 5 cm of the column compared to only 5% of the DF formulation of atrazine. This study indicates that starch encapsulation reduces atrazine movement to a greater extent than polymer additives and suggests that starch encapsulation may be an effective method of reducing atrazine leaching.

Soil biotic and biochemical factors in a long-term tillage and stubble management experiment on a vertisol. 1. Seedling inhibition by stubble

In a long-term experiment on a vertisol in southern Queensland, depression of vegetative growth of barley ( Hordeum vulgare L.) by stubble retention was far greater with zero tillage than with mechanical tillage of the fallow. The possible phytotoxic effects of stubble on barley and wheat ( Triticum aestivum L.) were investigated in seedling bioassays. Stubble collected from field plots just prior to planting did not reduce germination of wheat or barley seed but markedly reduced coleoptile length at 4 days. This effect of stubble became less apparent after 6 and 8 days, and was overcome by increasing water volume in the bioassay dish. Stubble absorbed 4.5–6 times its own weight of water and thereby competed with the germinating seed. Filtrates of stubble macerates in water, collected either before or after incubation of the saturated stubble, had no effect on coleoptile length indicating the absence of a water-soluble phytotoxin. Brown lesions on wheat coleoptiles (most apparent at 8 days) and roots were decreased by stubble but increased by more water in the bioassay dish. Alternaria sp. and two types of bacteria were associated with the coleoptile lesions, and Fusarium sp. and several types of bacteria were associated with root lesions. Surface sterilisation of seed reduced root lesions but not coleoptile lesions. Filtrates of both incubated and unincubated stubble macerates reduced coleoptile lesions. Poor early growth of barley in the field on zero-till, stubble-retained plots was not associated with incorporation of stubble into the drill slit in contact with the seed. Poor early growth was not overcome by nitrogen fertilizer drilled into the soil 2 months before planting. The quantities of air-dried stubble on the soil surface were capable of absorbing of the order of 4 mm rainfall. It is concluded that neither phytotoxins nor water absorption by the stubble were likely causes of the problem of poor early growth.

Leaching of Oxyfluorfen in Container Media

Bentgrass was used to bioassay oxyfluorfen in leaching experiments done in columns of soilless potting media and soils, with herbicide incorporated into the upper 2 to 4 cm. Depth of herbicide leaching increased in order in the following soils: peat and sand (1:1) mix, Stockton clay soil, Yolo fine sandy loam soil, and redwood bark and sand (3:1) mix. Depth of leaching was not related to soil organic matter content. Equilibration experiments showed that peat adsorbed 4 to 5 times more oxyfluorfen than redwood bark. Less leaching was observed in potting mixtures containing peat than bark. Raising the oxyfluorfen dose from 20 to 200 ppmw increased the depth of leaching and concentration of herbicide in the leachate, while a 10-fold increase in water volume had only a limited effect. Twenty ppmw of oxyfluorfen incorporated in the top of a peat-containing potting medium has a low risk of leaching out of the container.

Exponential increases in pulmonary intravascular and extravascular fluid volumes by overperfusion with dextran 70 in anesthetized dogs.

In the lung overperfused by dextran 70, it is not known how intravascular blood volume and extravascular water volume increase as a function of pulmonary microvascular pressure. To determine their characteristics, we produced an overperfusion state (high pressure and high blood flow) by infusing dextran 70 (100 ml/kg over 30 min) into 15 anesthetized dogs. Using the thermal and dye dilution technique, we simultaneously estimated the pulmonary blood volume (PBV) and the extravascular lung thermal volume (EVLTV), and correlated mathematically these variables with pulmonary artery end-diastolic pressure (PAEDP). Here, we defined PAEDP as the pulmonary microvascular pressure. From the values determined before, during and after dextran 70 infusion, we obtained the following exponential relations. PBV(ml/kg) = 30[1-0.902(e-0.021PAEDP(mmHg)) EVLTV(ml/kg) = 5.15(e0.027PAEDP (mmHg)) From these mathematical relations, we conclude that: (1) the pulmonary blood volume increases rapidly at low pressure and slowly at high pressure; and (2) the pulmonary extravascular water volume increases slowly at low pressure and then increases rapidly at high pressure. In addition, this equation indicates that the critical pressure from which the pulmonary extravascular water volume exceeds the upper limit of its normal volume is about 17 mmHg in PAEDP. Infusion of dextran 70 increased plasma macromolecular osmotic pressure from 20.8 +/- 0.6 (mean +/- SD) mmHg before infusion to 43.7 +/- 1.4 mmHg after infusion. Therefore, dextran 70 does not change the critical microvascular pressure against pulmonary edema.

Ecdysis in a parasitic nematode: direct evidence for an ecdysial factor from the head

Incubating intact Phocanema decipiens in 0.9% NaCl containing insect juvenile hormone 1 (JH) leads to an increase in water volume of the excretory cell as determined by exchange with 3H2O, while incubation in 0.9% NaCl without JH does not. Ligaturing the head end of the worm prevents this increase and injection of extracts of heads into worms stimulates an increase in water content. Application of extract of heads to excretory cells in vitro also leads to an increase in water content of the cells.

BIMODAL GAS EXCHANGE AND THE REGULATION OF OXYGEN UPTAKE IN HOLOTHURIANS

In air-saturated sea water, 60% of the total O2 uptake by Cucumaria frondosa (epifaunal) and Sclerodactyla briareus (infaunal) occurs through the respiratory trees. When the cloacal opening of C. frondosa is occluded, weight-specific O2 uptake decreases with weight more than in intact specimens, indicating an increasing dependence of large individuals on their respiratory trees. Likewise, cloaca occlusion results in a proportionately greater loss of oxyregulatory ability in large C. frondosa. Neither of these results occurs in S. briareus, which compensates for loss of the trees by increasing O2 uptake across the general body surface.In intact animals, the greater oxyregulatory ability of S. briareus relative to C. frondosa is also due to the former's having less of a decline in frequency combined with a more pronounced increase in volume per pumping cycle of the respiratory tree irrigation rhythm, resulting in an increase in total volume of water pumped, as Po2 declines; in C. frondosa, this volume decli...