High Levels Of Carbon Dioxide Research Articles

Mole-rats from higher altitudes have greater thermoregulatory capabilities

Subterranean mammals (those that live and forage underground) inhabit a challenging microenvironment, with high levels of carbon dioxide and low levels of oxygen. Consequently, they have evolved specialised morphological and physiological adaptations. For small mammals that inhabit high altitudes, the effects of cold are compounded by low oxygen partial pressures. Hence, subterranean mammals living at high altitudes are faced with a uniquely demanding physiological environment, which presumably necessitates additional physiological adjustments. We examined the thermoregulatory capabilities of two populations of Lesotho mole-rat Cryptomys hottentotus mahali that inhabit a ‘low’ (1600 m) and a ‘high’ (3200 m) altitude. Mole-rats from the high altitude had a lower temperature of the lower critical point, a broader thermoneutral zone, a lower thermal conductance and greater regulatory non-shivering thermogenesis than animals from the lower altitude. However, minimum resting metabolic rate values were not significantly different between the populations and were low compared with allometric predictions. We suggest that thermoregulatory costs may in part be met by animals maintaining a low resting metabolic rate. High-altitude animals may adjust to their cooler, more oxygen-deficient environment by having an increased non-shivering thermogenesis whilst maintaining low thermal conductance.

Impact of high water carbon dioxide levels on Atlantic salmon smolts ( Salmo salar L.): Effects on fish performance, vertebrae composition and structure

The role of high carbon dioxide (CO 2) levels on fish performance, bone structure/composition and as a potential cause of spinal deformities was studied. Two groups of fish were exposed to a low (control) and a high level of CO 2 for 135 days during the freshwater period. After smoltification, the fish were transferred to seawater and followed up for 517 days until they reached harvest weight (3.1 kg BW). Differences in body weight between the control and high CO 2 groups were observed. At the end of the freshwater period, average weight in the group exposed to high CO 2 levels was 20.9% lower than in the control group. Specific growth rates (SGR) from the start of the experiment (10 g BW) to smolt stage were 1.63 ± 0.04 and 1.36 ± 0.01 for the control group and the high CO 2 group, respectively. Differences in body weight were maintained during the initial stages of the seawater period, but were not observed at harvest weight. Nephrocalcinosis was not observed in any of the experimental groups at the end of the freshwater period and no external signs of spinal deformities were observed either at smolt stage or at harvest weight. X-rays revealed mild abnormalities in some vertebrae bodies, which could not be related to any experimental group. Despite the lack of signs of pathological bone alterations, the histological examination suggested that the exposure to high CO 2levels resulted in an increase in trabeculae volume and a higher rate of bone remodeling at the end of the freshwater period. Furthermore, fish exposed to a high CO 2 level presented a higher bone ash content at the end of the freshwater period. These differences could not be observed at the end of the grow-out period.

CO(2) signaling in guard cells: calcium sensitivity response modulation, a Ca(2+)-independent phase, and CO(2) insensitivity of the gca2 mutant.

Leaf stomata close in response to high carbon dioxide levels and open at low CO(2). CO(2) concentrations in leaves are altered by daily dark/light cycles, as well as the continuing rise in atmospheric CO(2). Relative to abscisic acid and blue light signaling, little is known about the molecular, cellular, and genetic mechanisms of CO(2) signaling in guard cells. Interestingly, we report that repetitive Ca(2+) transients were observed during the stomatal opening stimulus, low [CO(2)]. Furthermore, low/high [CO(2)] transitions modulated the cytosolic Ca(2+) transient pattern in Arabidopsis guard cells (Landsberg erecta). Inhibition of cytosolic Ca(2+) transients, achieved by loading guard cells with the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid and not adding external Ca(2+), attenuated both high CO(2)-induced stomatal closing and low CO(2)-induced stomatal opening, and also revealed a Ca(2+)-independent phase of the CO(2) response. Furthermore, the mutant, growth controlled by abscisic acid (gca2) shows impairment in [CO(2)] modulation of the cytosolic Ca(2+) transient rate and strong impairment in high CO(2)-induced stomatal closing. Our findings provide insights into guard cell CO(2) signaling mechanisms, reveal Ca(2+)-independent events, and demonstrate that calcium elevations can participate in opposed signaling events during stomatal opening and closing. A model is proposed in which CO(2) concentrations prime Ca(2+) sensors, which could mediate specificity in Ca(2+) signaling.

New JCAHO Pain Standard Bigger Threat to Patient Safety Than Envisioned

In Response: We appreciate the thoughtful commentary provided by Overdyk et al. (1) and the opportunity to clarify our recommendations for improved monitoring of patients (2). Joint Commission on Accreditation of Healthcare Organizations (JCAHO)-mandated pain management standards have increased the need for accurate monitoring to detect clinically significant hypoventilation and increase patient safety. It is likely that all patients who receive narcotic analgesics will have some degree of respiratory depression. As noted by Overdyk et al., respiratory rate is woefully inadequate as a monitor of ventilatory adequacy. Studies cited by Cashman and Dolin (3) reported decreased respiratory rate in only 1.1% of patients receiving narcotic analgesics. Yet respiratory depression was indicated by decreased oxygen saturation in 37% of patients receiving narcotics IM even when Fio2 was not specified. Witting et al. (4) were able to detect 88 of 92 cases of narcotic-induced hypercapnia with a pulse oximeter, as long as patients inhaled room air, indicating the sensitivity of Spo2 for detecting hypoventilation. Although we agree that high-risk patients need close monitoring for opioid-induced respiratory depression, Overdyk et al. disagree with our recommendation that pulse oximetry be used to monitor such patients. The basis for their disagreement is the observation that most high-risk patients receive supplemental inspired oxygen. Such therapy is based on the unproven, yet widely accepted, premise that moderate arterial hypoxemia is associated with increased morbidity and/or mortality. It is our contention that this premise is absolutely unfounded (5). When patients breathe room air, without supplemental oxygen, the pulse oximeter has been demonstrated to be a sensitive monitor of ventilation (4,6). Capnography has been offered as a means of monitoring ventilatory adequacy (7). However, this technique has failed to demonstrate efficacy in clinical practice (8,9). It is possible that the pulse oximeter is the only clinically useful monitor of ventilation, as long as the inspired oxygen concentration is 0.21. An increase in Fio2 will increase the arterial partial pressure of oxygen but will do nothing to correct the pathological condition causing arterial hypoxemia (7,8). Should patients demonstrate a decrease in oxygen saturation while breathing room air, the clinician, when alerted, may investigate to determine if arterial hypoxemia is secondary to hypoventilation, low, but finite, ventilation-to-perfusion ratio, or right-to-left intrapulmonary shunting of blood. Contrary to concerns expressed by Overdyk et al., we feel that patients at risk for developing, but not yet manifesting, arterial hypoxemia are best monitored while breathing room air, which will allow detection and correction of pulmonary dysfunction sooner than will occur with an Fio2 >0.21 (10). Timely detection of inadequate ventilation is essential so that appropriate therapy may be instituted before dangerously high levels of carbon dioxide result in even more profound respiratory depression. It is physiologically not possible for a patient breathing room air to develop a Paco2 >75 mm Hg while maintaining an Spo2 >90%. However, it is possible for a patient to breathe as little as 25% inspired oxygen to maintain Spo2 >90%, with a Paco2 > 100 mm Hg! At this level, CO2 narcosis may further impair ventilation. Respiratory arrest and rapid, profound arterial hypoxemia will likely then occur. Weighing the risks (if there are any) of mild arterial hypoxemia (Spo2 > 80%) against the hazard of undetected profound hypoventilation, leads us to the conclusion that the pulse oximeter should be viewed as an effective means of monitoring adequacy of ventilation but only if inspired air is not supplemented with additional oxygen. Hector Vila Jr, MD John B. Downs, MD Anesthesiology Division Department of Interdisciplinary Oncology H. Lee Moffitt Cancer Center and Research Institute University of South Florida College of Medicine Tampa, FL [email protected]

Live chilling of Atlantic salmon ( Salmo salar) combined with mild carbon dioxide anaesthesia : I. Establishing a method for large-scale processing of farmed fish

The goal of the present study is to evaluate the combined effect of live chilling and carbon dioxide narcosis as a potential stunning/chilling method for Atlantic salmon in a commercial slaughter line. Water quality parameters in cage and RSW tanks, handling stress (white muscle pH), body temperature profile as affected by processing, rigor mortis development, and fillet quality (protein and textural properties, fillet pH and colour) after ice storage for 1 and 2 weeks, were evaluated. Fish from sea cage, live chilling RSW tank and carbon dioxide stunning RSW tank were compared. Effects of pumping and live chilling on blood vessels in gill arches were also evaluated. Under the prevailing slaughter conditions, it was shown that by using live chilling with a Δ T (SW vs. RSW) of 8–10 °C, oxygen levels (60–156% saturation) and moderate carbon dioxide levels (37–80 mg l − 1 ), it was possible to process Atlantic salmon without inflicting excessive handling stress. Consequently, the fish exhibited a long pre-rigor period (about 24 h) giving ample time for pre-rigor processing. Moreover, no detrimental effects on blood vessels in gills and fillet quality were observed, i.e. the processed fish were not different from the fish taken directly from sea cage. The proposed stunning method of combining live chilling and moderate levels of carbon dioxide in a single tank was considered to be superior to the traditional carbon dioxide stunning method using very high levels of carbon dioxide in a comparatively small tank.

The Effect of Ethanol Dip and Modified Atmosphere on Prevention of Botrytis Rot of Table Grapes

Grape (Vitis vinifera) storage requires stringent control of gray mold caused by Botrytis cinerea. The commercial practice is dependent on sulfur dioxide (SO2) as a fumigant, which is applied by various means with well-known advantages and disadvantages. Many alternative technologies were developed over the years, most of them with limited efficacy or applicability. Modified atmosphere of table grapes suffers from a narrow threshold between control of gray mold and damage to the berries and stems due to high level of carbon dioxide (CO2) within the film-enclosed package. We demonstrated in the past that dipping table grapes in ethanol after harvest has a very pronounced effect on prevention of decay. However, ethanol does not leave a protective residue within the grapes, so it is not expected to prevent latent infections from developing decay nests during prolonged storage. However, if grapes of cultivar Superior were treated with ethanol and then subjected to a modified atmosphere using plastic films (Xtend), we achieved an additive effect and observed persistent control of gray mold without injury to the grapes. The advantage of this plastic film was mainly in its water conductance, which prevented accumulation of free water that is often the limiting factor in modified atmosphere packaging. This combination results in greater decay control, which is a prerequisite for commercial applicability. If undesired aftertaste did develop within the fruit due to the modified atmosphere, 1 day of exposure to ambient air was sufficient to dissipate it.

Nitrate assimilation in plant shoots depends on photorespiration.

Photorespiration, a process that diminishes net photosynthesis by approximately 25% in most plants, has been viewed as the unfavorable consequence of plants having evolved when the atmosphere contained much higher levels of carbon dioxide than it does today. Here we used two independent methods to show that exposure of Arabidopsis and wheat shoots to conditions that inhibited photorespiration also strongly inhibited nitrate assimilation. Thus, nitrate assimilation in both dicotyledonous and monocotyledonous species depends on photorespiration. This previously undescribed role for photorespiration (i) explains several responses of plants to rising carbon dioxide concentrations, including the inability of many plants to sustain rapid growth under elevated levels of carbon dioxide; and (ii) raises concerns about genetic manipulations to diminish photorespiration in crops.

High levels of atmospheric carbon dioxide necessary for the termination of global glaciation.

The possibility that the Earth suffered episodes of global glaciation as recently as the Neoproterozoic period, between about 900 and 543 million years ago, has been widely discussed. Termination of such 'hard snowball Earth' climate states has been proposed to proceed from accumulation of carbon dioxide in the atmosphere. Many salient aspects of the snowball scenario depend critically on the threshold of atmospheric carbon dioxide concentrations needed to trigger deglaciation. Here I present simulations with a general circulation model, using elevated carbon dioxide levels to estimate this deglaciation threshold. The model simulates several phenomena that are expected to be significant in a 'snowball Earth' scenario, but which have not been considered in previous studies with less sophisticated models, such as a reduction of vertical temperature gradients in winter, a reduction in summer tropopause height, the effect of snow cover and a reduction in cloud greenhouse effects. In my simulations, the system remains far short of deglaciation even at atmospheric carbon dioxide concentrations of 550 times the present levels (0.2 bar of CO2). I find that at much higher carbon dioxide levels, deglaciation is unlikely unless unknown feedback cycles that are not captured in the model come into effect.

Germination of penicillium paneum Conidia is regulated by 1-octen-3-ol, a volatile self-inhibitor.

Penicillium paneum is an important contaminant of cereal grains which is able to grow at low temperature, low pH, high levels of carbon dioxide, and under acid conditions. P. paneum produces mycotoxins, which may be harmful to animals and humans. We found that conidia in dense suspensions showed poor germination, suggesting the presence of a self-inhibitor. A volatile compound(s) produced by these high-density conditions also inhibited mycelial growth of different species of fungi belonging to a variety of genera, suggesting a broad action range. The heat-stable compound was isolated by successive centrifugation of the supernatant obtained from spore suspensions with a density of 10(9) conidia ml(-1). By using static headspace analyses, two major peaks were distinguished, with the highest production of these metabolites after 22 h of incubation at 25 degrees C and shaking at 140 rpm. Gas chromatography coupled with mass spectra analysis revealed the compounds to be 3-octanone and 1-octen-3-ol. Notably, only the latter compound appeared to block the germination process at different developmental stages of the conidia (swelling and germ tube formation). In this study, 1-octen-3-ol influenced different developmental processes during the P. paneum life cycle, including induction of microcycle conidiation and inhibition of spore germination. Therefore, the compound can be considered a fungal hormone during fungal development.

Lifetime-based optical sensor for high-level pCO 2 detection employing fluorescence resonance energy transfer

An optical sensor for the measurement of high levels of carbon dioxide in gas phase has been developed. It is based on fluorescence resonance energy transfer (FRET) between a long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye are both immobilised in a hydrophobic silica sol–gel/ethyl cellulose hybrid matrix material. Tetraoctylammonium hydroxide (TOA-OH) is used as an internal buffering system. Fluorescence lifetime is measured in the frequency domain, using low-cost phase modulation measurement technology. The use of Sudan III as an acceptor dye has enabled the sensor to have a dynamic range up to 100% carbon dioxide. The sensor displays 11.2° phase shift between the limit of detection (LOD) of 0.06 and 100% CO 2 with a resolution of better than 2%. The encapsulation in the silica/polymer hybrid material has provided the sensor with good mechanical and chemical stability. The effect of molecular oxygen, humidity and temperature on the sensor performance was studied in detail.

Physiological responses of the Asian sea bass, Lates calcarifer to water quality deterioration during simulated live transport: acidosis, red-cell swelling, and levels of ions and ammonia in the plasma

Water is a major expense when air-freighting live fish. However, reducing the volume of water relative to the amount of product usually results in more rapid water quality deterioration and higher mortality due to the higher concentration of excretory products in closed transport systems. The major water quality effects experienced by fish during transport are: low dissolved oxygen levels due to oxygen consumption by respiration; accumulation of carbon dioxide from respiration; depression of pH caused by carbon dioxide accumulation; and increased ammonia levels resulting from ammonia excretion. The physiological responses of seawater-adapted barramundi, Lates calcarifer, were studied during simulated live transport and transport under circumstances of elevated CO 2 or NH 3. Blood samples were removed from fish exposed to these treatments and compared to samples from control fish, (free in the tank) and fish confined in a box but with free-flowing seawater. Analysing the blood samples showed that simulated transport caused the plasma pH of the fish to fall, threatening the blood's ability to transport oxygen, but the red blood cells apparently defended their internal pH and oxygen transport capacity, and swelled measurably as a result. Exposing fish to unusually high carbon dioxide or ammonia levels caused plasma pH to fall to near lethal levels. The effects of both carbon dioxide and ammonia need to be considered when studying the responses of barramundi to live transport. Water quality parameters during fish transport do not act in isolation. Attempts to reduce carbon dioxide accumulation, for example, by using a buffer to control the water pH, may influence the fish's ability to excrete ammonia.

Transport of silver catfish ( Rhamdia quelen) fingerlings at different times, load densities, and temperatures

Silver catfish ( Rhamdia quelen) fingerlings (5–10 cm) were caught from a fish culture pond and placed in a tank for stomach emptying for 24 h. Fingerlings were then weighed and placed in plastic bags (5 l) with 1.5 l water and oxygen, which were kept at temperatures of 15, 20, and 25 °C. The load densities tested were 50, 67, 87, and 168 g l −1. When bags were opened after 6, 12, or 24 h, mortality, dissolved oxygen, pH, total ammonia, non-ionized ammonia, total hardness, nitrite, total alkalinity, and carbon dioxide levels were determined. There was fingerling mortality only at the load density of 168 g l −1 after 24 h of transport at 20 and 25 °C, suggesting that mortality increased with temperature and time of transport. The dissolved oxygen levels in the water were reduced throughout 24 h of transport in the load density of 168 g l −1 at 20 and 25 °C, but remained unchanged at the other load densities. The pH decreased significantly at all load densities and temperatures throughout 24 h. Total alkalinity, total ammonia, and carbon dioxide levels increased significantly up to 24 h of transport in all treatments. Non-ionized ammonia and nitrite levels were below 0.02 and 0.06 mg l −1, respectively. Total hardness ranged from 20 to 48 mg l −1 CaCO 3. The best temperature for transporting fingerlings of this species in plastic bags is 15 °C, because up to 24 h there was no significant mortality even at the load density of 168 g l −1, dissolved oxygen levels were still high, and total ammonia and carbon dioxide presented the lowest increase. Transport at 25 °C and a load density of 168 g l −1 must not exceed 6 h due to the high levels of ammonia and carbon dioxide and low dissolved oxygen levels in the water.

Scots pine growth trends in northwestern kola peninsula as an indicator of positive changes in the carbon cycle

Growth trends of Scots pine (Pinus sylvestris) at its northernmost extent may be an indicator of changes in the carbon cycle of terrestrial forest ecosystems. Using a method which removed age trends from the data, a time-series analysis of annual radial increment in wood over the last few decades compared with the period of the last registered warming (maximum around 1930–40), revealed elevated growth of 78% for trees 0–20 years old, 56% for trees 21–40 years old, 21% for trees 41–60 years old, and 10% for trees more than 101 years old. Increments of trees in the61–80 and 81–100 years old age classes from the two periods were similar. The higher rate of growth in recent times occurred despite a decrease in temperature after about 1940 and significant air pollution. During the last century growth of Scots pine increased for trees in all age groups, except for trees in the 81–100 year old age class for which it was constant. The average rates of growth were estimated at 0.016 mm/year for trees in the 0–20 year age class, 0.012 mm/year for the 21–40 year age class, 0.005 mm/year for the 41–60 year age class, 0.008 mm/year for the 61–80 year age class and 0.006 mm/year for trees in the greater than 101 year age class. The growth trends were unstable over time and took place concurrent with increasing oscillations in radial increment. The most probable reasons for the marked increase in radial increment growth of Scots pine in this region are climate warming and higher levels of carbon dioxide. Together these may produce a synergistic effect on growth.

Renewable Energy: A Viable Choice

Renewable energy systems—notably solar, wind, and biomass—are poised to play a major role in the energy economy and in improving the environmental quality of the United States. California’s energy crisis focused attention on and raised fundamental questions about regional and national energy strategies. Prior to the crisis in California, there had been too little attention given to appropriate power plant siting issues and to bottlenecks in transmission and distribution. A strong national energy policy is now needed. Renewable technologies have become both economically viable and environmentally preferable alternatives to fossil fuels. Last year the United States spent more than $600 billion on energy, with U.S. oil imports climbing to $120 billion, or nearly $440 of imported oil for every American. In the long term, even a natural gasbased strategy will not be adequate to prevent a buildup of unacceptably high levels of carbon dioxide (CO2) in the atmosphere. Both the Intergovernmental Panel on Climate Change’s (IPCC) recent Third Assessment Report and the National Academy of Sciences’ recent analysis of climate change science concluded that climate change is real and must be addressed immediately—and that U.S. policy needs to be directed toward implementing clean energy solutions. 1 Renewable energy technologies have made important and dramatic technical, economic, and operational advances during the past decade. A national energy policy and climate change strategy should be formulated around these advances. Despite dramatic technical and economic advances in clean energy systems, the United States has seen far too little research and development (R&D) and too few incentives and sustained programs to build markets for renewable energy technologies and energy efficiency programs. 2 Not since the late1970s has there been a more compelling and conducive environment for an integrated, large-scale approach to renewable energy innovation and market expansion. 3 Clean, low-carbon energy choices now make both economic and environmental sense, and they provide the domestic basis for our energy supply that will provide security, not dependence on unpredictable overseas fossil fuels. Energy issues in the United States have created “quick fix” solutions that, while politically expedient, will ultimately do the country more harm than good. It is critical to examine all energy options, and never before have so many technological solutions been available to address energy needs. In the near term, some expansion of the nation’s fossil fuel (particularly natural gas) supply is warranted to keep pace with rising demand, but that expansion should be balanced with measures to develop cleaner energy solutions for the future. Our best short-term options for the United States are energy efficiency, conservation, and expanded markets for renewable energy.

Phospho enolpyruvate carboxylase from cherimoya fruit: properties, kinetics and effects of high CO 2

Phospho enolpyruvate carboxylase (PEPC, EC 4.1.1.31) regulatory properties were studied in non-photosynthetic (mesocarp) and photosynthetic (peel) tissues from cherimoya ( Annona cherimola Mill.) fruit stored in air, in order to gain a better understanding of in vivo enzyme regulation. Analyses were also performed with fruit treated with 20% CO 2–20% O 2 to define the role of PEPC as part of an adaptive mechanism to high external carbon dioxide levels. The results revealed that the special kinetic characteristics of the enzyme from mesocarp—high V max and low sensibility to l-malate inhibition - are related to the active acid metabolism of these fruits and point to a high rate of reassimilation of respired CO 2 into keto-acids. With respect to fruit stored in air, PEPC in crude extracts from CO 2-treated cherimoyas gave a similar V max (1.12±0.03 μkat·mg −1 protein), a lower apparent K m (68±9 μM for PEP) and a higher I 50 of l-malate (5.95±0.3 mM). These kinetic values showed the increase in the affinity of this enzyme toward one of its substrate, PEP, by elevated external CO 2 concentrations. The lower K m value and lower sensitivity to l-malate are consistent with higher in vivo carboxylation reaction efficiency in CO 2-treated cherimoyas, while pointing to an additional enzyme regulation system via CO 2.

Effect of relative humidity on the susceptibility of Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae) to two modified atmospheres

It is known that modified atmospheres (MA) created in a storage environment, involving high carbon dioxide (CO 2) levels (hypercarbia) or low oxygen (O 2) levels (anoxia) are detrimental to bruchid pests of grain legumes. The possibility of enhancing MA action by increasing or decreasing the relative humidity (r.h.) conditions in storage at 25±2°C was investigated against Callosobruchus maculatus (F.), a major bruchid pest of stored cowpea seeds. Mortality of eggs and adults of the bruchid in 70% CO 2 in air and 1.0% O 2 in nitrogen (N 2) was higher at 10±3% and 34±2% than at 70±2% and 90±3% r.h. Mortality of larvae and pupae of the bruchid in the atmospheres was not affected by the r.h. in storage. Development period was longer for adults emerging from bruchid eggs exposed for 12 h to these atmospheres at the lower r.h. Freshly emerged adult bruchids from treated eggs also laid fewer eggs after 12 h of exposure to these atmospheres at the lower r.h.

Morphogenèse de la vigne in vitro sous atmosphère enrichie en gaz carbonique : importance de l'antériorité morphogénétique des microboutures et du nombre de subcultures

This study reveals that morphogenesis of grapevine plants (Vitis vinifera L.) produced in vitro under carbon dioxide enriched atmosphereis largely determined by the morphogenetic pattern of vitroplants on which microcuttings were harvested. The presence of tendrils on shoots or shoot parts from which microcuttings were made was essential to obtain a high percentage of adult vitroplants with ternary sequence of tendrils. Therefore, under in vitro culture conditions, the ability of the axillary meristem to produce tendrils is closely correlated with the ability of the apical meristem from which it originated. The interest of these results is discussed from a fundamental standpoint. It allows to suggest an improved process of adult vitroplants production under high carbon dioxide level in which the relative importance of the selection of microcuttings and the number of subcultures is defined.Key words: maturation, micropropagation, tendrils, Vitis vinifera.

Artificial carbon dioxide source to attract lesser cornstalk borer (Lepidoptera: Pyralidae) larvae.

Different combinations of urea, urease (in jack bean meal, Canavalia DC.), and water were tested as carbon dioxide sources to attract larvae of lesser cornstalk borer, Elasmopalus lignosellus (Zeller), by using olfactory bioassays with an olfactometer and infrared gas analysis. A combination of urea, jack bean meal, and water was necessary to release a high level of carbon dioxide to attract the larvae. Different proportions of the three ingredients had different carbon dioxide release rates and exhibited different levels of attraction to the larvae. When carbon dioxide concentration was too high, attractiveness declined. Combinations with different amounts of water remained attractive for a period of up to 3 d, depending on the moisture of the samples. When Zonolite was used to simulate the soil conditions in the olfactometer, significantly more larvae located the area near the artificial carbon dioxide sources compared with the control. When combined with the artificial carbon dioxide sources, three insecticides (Lorsban, Temik, and Force) did not obviously affect the release rates of carbon dioxide, and more larvae were attracted to samples with the carbon dioxide source than to the samples without carbon dioxide.

The cost of sequestering carbon on private forest lands

The increase of carbon dioxide in the atmosphere and its possible greenhouse effect on global climate has become one of today's major environmental issues. Utility/coal companies which produce high levels of carbon dioxide are interested in mitigating their emissions by sequestering carbon in trees. This study proposed to investigate the amount of money that utility companies would have to pay private forest landowners to sequester additional tonnes of carbon in their forests. Analyses were conducted to calculate the annual financial compensation/incentives necessary to (1) compensate forest landowners who apply economically sub-optimal rotations to sequester maximum carbon; or (2) motivate private landowners to convert unstocked lands into productive forest lands to sequester carbon. Biological and financial analyses were conducted using Loblolly pine ( Pinus taeda) on a range of site indices. Applying the Faustmann formula, the amount of necessary compensation/incentive was calculated as the difference between the soil expectation value (SEV) of the economically optimal rotation and the SEV of the biologically optimal rotation which maximizes mean annual increment (MAI) of sawtimber and, therefore, maximizes carbon stored in the forest and in the long-lived wood products. Results indicate that the carbon sequestration difference between the MAI of the optimal economic rotation and that of the optimal carbon rotation may be up to 0.79 t of carbon per hectare. Planting unstocked land may store an additional 1.03–3.77 t of carbon per hectare per year. The annual compensation values tend to increase as real interest rates increase. The minimum annual compensation is $0.84 per hectare using an interest rate of 2.5% on site index 50 land. The maximum annual compensation is $72.79 per hectare using an interest rate of 12.5% on site index 90 land. The average costs of sequestering an additional tonne of carbon on lands already intensively managed vary from $4.18 to $181.27. The average costs of sequestering an additional tonne of carbon on unstocked land range from $0.74 to $27.32.

Effects of dissolved carbon dioxide on the physiology and behavior of fish in artificial streams

A new technology for treating waters contaminated with acid mine drainage involves the dissolution of limestone particles using carbon dioxide at pressures above ambient. Because of the fish health risks associated with episodes of high carbon dioxide levels in treated waters, we subjected three species of fish, brook trout (Salvelinus fontinalis), slimy sculpin (Cottus cognatus), and blacknose dace (Rhinichthys atratulus), to 24 h exposures of elevated dissolved carbon dioxide (CO2) at three levels, ranging from 1.0 (low) to 6.3 (high)%, under laboratory conditions. We measured blood physiological variables as well as behavior, including feeding responses, before, during, and after exposure. Physiological responses differed by species, but all species had elevated hematocrits after 1 h of exposure. Brook trout hematocritis were higher at medium and high levels of CO2 than in a control group (0.0% CO2) after 24 h of exposure. Slimy sculpin hematocrits were higher in medium- and high-level exposure groups than in controls after 1 h, but not after 24 h, of exposure. Blacknose dace hematocrits were higher in all three exposure groups than in controls after 1 h but only in medium-level exposure groups after 24 h. Brook trout plasma glucose was significantly higher in medium- and high-level exposure groups after 1 h, and in the high-level group after 24 h, than in controls. Slimy sculpin plasma glucose was not significantly different in elevated CO2 exposure groups from that of controls throughout exposure. Branchial ventilation was significantly greater in all species at elevated CO2 during exposure, indicating stress; however, no difference was observed between treatment and control groups of blacknose dace after 24 h, indicating acclimation. Pectoral fin beats and cough rates were not consistently related to CO2 exposure throughout the study. Brook trout had the longest lasting reaction to stress at lower levels of CO2 among the three species tested. Many of the 11 observed behavioral variables, related to swimming, feeding, social, and illness factors, were affected by elevations of dissolved CO2. Two to seven behavioral variables (18-64% of those measured) were affected by treatment level of dissolved CO2 with a trend by species for the number of variables affected: brook trout > blacknose dace > slimy sculpin. However, behavioral sensitivity to treatment level was greatest in blacknose dace. Recovery to pre-treatment activity rates for most behavior patterns (including feeding) was observed 24 h after cessation of exposure in all three species. Recovery was independent of treatment level, was most rapid in blacknose dace, and was slowest in brook trout. Overall, slimy sculpin was least affected behaviorally by elevated CO2. Although all three species showed stress response and changes in behavior at moderate levels of CO2 (> or = 2%), brook trout and blacknose dace showed evidence of ability to avoid harmful CO2 levels by swimming out of affected waters, whereas the slimy sculpin showed minimal behavioral changes despite remaining in place during exposure. Thus, predation risk and other sources of mortality seem minimal in the event of technological malfunction at a stream treatment site involving the use of CO2 under pressure.