共查询到20条相似文献,搜索用时 203 毫秒
1.
The combined effects of ocean warming and acidification were compared in larvae from two populations of the cold-eurythermal
spider crab Hyas araneus, from one of its southernmost populations (around Helgoland, southern North Sea, 54°N, habitat temperature 3–18°C; collection:
January 2008, hatch: January–February 2008) and from one of its northernmost populations (Svalbard, North Atlantic, 79°N,
habitat temperature 0–6°C; collection: July 2008, hatch: February–April 2009). Larvae were exposed to temperatures of 3, 9
and 15°C combined with present-day normocapnic (380 ppm CO 2) and projected future CO 2 concentrations (710 and 3,000 ppm CO 2). Calcium content of whole larvae was measured in freshly hatched Zoea I and after 3, 7 and 14 days during the Megalopa stage.
Significant differences between Helgoland and Svalbard Megalopae were observed at all investigated temperatures and CO 2 conditions. Under 380 ppm CO 2, the calcium content increased with rising temperature and age of the larvae. At 3 and 9°C, Helgoland Megalopae accumulated
more calcium than Svalbard Megalopae. Elevated CO 2 levels, especially 3,000 ppm, caused a reduction in larval calcium contents at 3 and 9°C in both populations. This effect
set in early, at 710 ppm CO 2 only in Svalbard Megalopae at 9°C. Furthermore, at 3 and 9°C Megalopae from Helgoland replenished their calcium content to
normocapnic levels and more rapidly than Svalbard Megalopae. However, Svalbard Megalopae displayed higher calcium contents
under 3,000 ppm CO 2 at 15°C. The findings of a lower capacity for calcium incorporation in crab larvae living at the cold end of their distribution
range suggests that they might be more sensitive to ocean acidification than those in temperate regions. 相似文献
2.
Various iron oxides are used for Fenton reactions to degrade organic pollutants. The degradation efficiency may be improved by transforming an iron oxide phase to another. Here, we report on the transformation of goethite into hematite by thermal treatment at 400 °C. The products were analyzed by X-ray diffractometry, Raman spectroscopy, scanning electron microscopy and N 2-physisorption. The catalytic activities were measured for orange II bleaching at initial concentration of 25 mg L ?1, pH 3, catalyst concentration of 0.2 g L ?1; 5 mM H 2O 2, 30 °C. Results show that the synthesized goethite was successfully transformed into hematite, and the specific surface area of the material increased from 134 to 163 m 2 g ?1. The bleaching efficiency of the orange II dye reached 100 % for the hematite product, versus 78 % for goethite. Therefore, a moderate thermal treatment of a plasma-synthesized goethite improves the catalytic oxidation of organic pollutants. 相似文献
3.
The underlying physiological mechanisms explaining why the adult penaeid prawn Litopenaeus stylirostris cannot successfully face heavy stressful events on the low edge of its thermopreferendum (20–22°C) were studied during the
austral winter. Prawns were studied during recovery from net fishing and rapid transfer from outdoor earthen ponds into indoor
facilities. This was assimilated to a predator–prey interaction. O 2-consumption, hemolymph osmotic pressure (OP h), arterial O 2 partial pressure (PO 2), a–v O 2-capacitance and mortality rates were analysed. Data were compared to similar challenges performed at 28°C during the austral
summer. At 20–22°C, mortality of up to 70% was observed after 2 days whereas at 28°C, maximum mortality was 3–5%. Mortality
occurred when OP h shifted towards equilibrium with seawater, the resting O 2-consumption, the a–v O 2-capacitance and the arterial PO 2 went down to minimal values. These events can be counterbalanced by transiently hyper-oxygenating the hemolymph or by blocking
the OP h shift in isosmotic water (Wabete et al. in Aquaculture 260:181–193, 2006): both led to a dramatic decrease in mortality. It is concluded that in penaeid prawns L. stylirostris, a mismatch between O 2-demand and O 2-supply contributes to setting the geographical limits for this animal species through an impairment of their hemolymph O 2-carrying capacity during heavy stressful events like chasing by predators. 相似文献
4.
The impact of elevated CO 2 and temperature on photosynthesis and calcification in the symbiont-bearing benthic foraminifer Marginopora vertebralis was studied. Individual specimens of M. vertebralis were collected from Heron Island on the southern Great Barrier Reef (Australia). They were maintained for 5 weeks at different temperatures (28, 32 °C) and pCO 2 (400, 1,000 µatm) levels spanning a range of current and future climate-change scenarios. The photosynthetic capacity of M. vertebralis was measured with O 2 microsensors and a pulse-amplitude-modulated chlorophyll (Chl) fluorometer, in combination with estimates of Chl a and Chl c 2 concentrations and calcification rates. After 5 weeks, control specimens remained unaltered for all parameters. Chlorophyll a concentrations significantly decreased in the specimens at 1,000 µatm CO 2 for both temperatures, while no change in Chl c 2 concentration was observed. Photoinhibition was observed under elevated CO 2 and temperature, with a 70–80 % decrease in the maximum quantum yield of PSII. There was no net O 2 production at elevated temperatures in both CO 2 treatments as compared to the control temperature, supporting that temperature has more impact on photosynthesis and O 2 flux than changes in ambient CO 2. Photosynthetic pigment loss and a decrease in photochemical efficiency are thus likely to occur with increased temperature. The elevated CO 2 and high temperature treatment also lead to a reduction in calcification rate (from +0.1 to >?0.1 % day ?1). Thus, both calcification and photosynthesis of the major sediment-producing foraminifer M. vertebralis appears highly vulnerable to elevated temperature and ocean acidification scenarios predicted in climate-change models. 相似文献
5.
Bioerosion is one of the most important structuring forces in coral reef communities. The bioerosion impact of several species of fish, sponges and sea urchins have been estimated in the Caribbean; however, there is no information for one important species, the red sea urchin Echinometra viridis. This species can be found in high densities in many localities. In this study, bioerosion rates for E. viridis were estimated in two patch reefs off La Parguera, southwest Puerto Rico, using the population size-class distribution, average densities, and the CaCO 3 content in fecal pellets produced over 24 h. Average densities of urchins along four depth intervals were estimated using 40-m transect lines and 1-m 2 quadrats. Average size and size-structure distribution were estimated by measuring the diameter of 180–220 urchins haphazardly collected at each of the four depth intervals. The ignition–loss method was used to estimate the daily rate of bioerosion. Fecal pellets produced by the urchins over a 24 h period were collected in buckets, rinsed in fresh water, dried for 24 h at 70°C, and then burned in a furnace at 550°C, first to eliminate organics, and then at 1000°C until constant weight to determine the amount of calcium carbonate (CaCO 3) in the fecal pellets. HCl (10%) was then added to the remainder of the sample to test for presence of CaCO 3. Average individual CaCO 3 bioerosion rates were estimated at 0.181±0.104 g day -1. Average densities (0.77–62.0 ind. m -2), size (2.01–2.44 cm) and average bioerosion rates (0.114–4.14 kg m -2 year -1) were significantly higher in shallow areas (1–3 m) in both reefs. Bioerosion rates were low compared to those reported for parrotfish, endolithic sponges and the black sea urchin D. antillarum, but they were higher than those reported for other small-sized sea urchins in the Caribbean and the Indo-Pacific. 相似文献
6.
AbstractOxidative removal of toluene using copper and cobalt bimetallic catalysts with varying molar ratios supported on sepiolite was investigated. The catalysts prepared by a deposition precipitation method and were characterized using X-ray diffraction, nitrogen adsorption-desorption, field emission scanning electron microscopy, H 2-temperature-programmed reduction, transmission electron microscope, and inductive coupled plasma atomic emission spectroscopy. The species supported on sepiolite are Co 3O 4, CuO, and CuCo 2O 4. The activities of the tested catalysts increased in the order 0Co-4Cu/Sep <1Co-3Cu/Sep <4Co-0Cu/Sep <1Co-1Cu/Sep <3Co-1Cu/Sep. The latter exhibiting 90% toluene oxidative degradation at 288?°C within 15?h, having high selectivity towards CO 2, and being stable at 300?°C up to 15?h. In conclusion, this study showed that sepiolite has excellent properties as a support. 相似文献
7.
Ocean acidification and global warming are occurring concomitantly, yet few studies have investigated how organisms will respond
to increases in both temperature and CO 2. Intertidal microcosms were used to examine growth, shell mineralogy and survival of two intertidal barnacle post-larvae,
Semibalanus balanoides and Elminius modestus, at two temperatures (14 and 19°C) and two CO 2 concentrations (380 and 1,000 ppm), fed with a mixed diatom-flagellate diet at 15,000 cells ml −1 with flow rate of 10 ml −1 min −1. Control growth rates, using operculum diameter, were 14 ± 8 μm day −1 and 6 ± 2 μm day −1 for S. balanoides and E. modestus, respectively. Subtle, but significant decreases in E. modestus growth rate were observed in high CO 2 but there were no impacts on shell calcium content and survival by either elevated temperature or CO 2. S. balanoides exhibited no clear alterations in growth rate but did show a large reduction in shell calcium content and survival under
elevated temperature and CO 2. These results suggest that a decrease by 0.4 pH (NBS) units alone would not be sufficient to directly impact the survival of barnacles during the first month post-settlement.
However, in conjunction with a 4–5°C increase in temperature, it appears that significant changes to the biology of these
organisms will ensue. 相似文献
8.
The rising global population is inducing a fast increase in the amount of municipal waste and, in turn, issues of rising cost and environmental pollution. Therefore, alternative treatments such as waste-to-energy should be developed in the context of the circular economy. Here, we review the conversion of municipal solid waste into energy using thermochemical methods such as gasification, combustion, pyrolysis and torrefaction. Energy yield depends on operating conditions and feedstock composition. For instance, torrefaction of municipal waste at 200 °C generates a heating value of 33.01 MJ/kg, while the co-pyrolysis of cereals and peanut waste yields a heating value of 31.44 MJ/kg at 540 °C. Gasification at 800 °C shows higher carbon conversion for plastics, of 94.48%, than for waste wood and grass pellets, of 70–75%. Integrating two or more thermochemical treatments is actually gaining high momentum due to higher energy yield. We also review reforming catalysts to enhance dihydrogen production, such as nickel on support materials such as CaTiO3, SrTiO3, BaTiO3, Al2O3, TiO3, MgO, ZrO2. Techno-economic analysis, sensitivity analysis and life cycle assessment are discussed. 相似文献
9.
Ocean acidification is elicited by anthropogenic carbon dioxide emissions and resulting oceanic uptake of excess CO 2 and might constitute an abiotic stressor powerful enough to alter marine ecosystem structures. For surface waters in gas-exchange equilibrium with the atmosphere, models suggest increases in CO 2 partial pressure ( pCO 2) from current values of ca. 390 μatm to ca. 700–1,000 μatm by the end of the century. However, in typically unequilibrated coastal hypoxic regions, much higher pCO 2 values can be expected, as heterotrophic degradation of organic material is necessarily related to the production of CO 2 (i.e., dissolved inorganic carbon). Here, we provide data and estimates that, even under current conditions, maximum pCO 2 values of 1,700–3,200 μatm can easily be reached when all oxygen is consumed at salinities between 35 and 20, respectively. Due to the nonlinear nature of the carbonate system, the approximate doubling of seawater pCO 2 in surface waters due to ocean acidification will most strongly affect coastal hypoxic zones as pCO 2 during hypoxia will increase proportionally: we calculate maximum pCO 2 values of ca. 4,500 μatm at a salinity of 20 ( T = 10 °C) and ca. 3,400 μatm at a salinity of 35 ( T = 10 °C) when all oxygen is consumed. Upwelling processes can bring these CO 2-enriched waters in contact with shallow water ecosystems and may then affect species performance there as well. We conclude that (1) combined stressor experiments ( pCO 2 and pO 2) are largely missing at the moment and that (2) coastal ocean acidification experimental designs need to be closely adjusted to carbonate system variability within the specific habitat. In general, the worldwide spread of coastal hypoxic zones also simultaneously is a spread of CO 2-enriched zones. The magnitude of expected changes in pCO 2 in these regions indicates that coastal systems may be more endangered by future global climate change than previously thought. 相似文献
10.
The Au/Al 2O 3 and Au–Rh/Al 2O 3 catalysts were prepared by deposition–precipitation. The promotional effect of Rh on the performance of the Au/Al 2O 3 catalyst for CO oxidation was studied. The results indicate that using Au/Al 2O 3 catalyst, CO can be completely oxidized at 0°C or much lower temperature but the catalyst deactivated very fast. Rh can improve
the stability of Au/Al 2O 3 catalyst more than 10 times, which gives an important hint to develop high stable catalyst for CO oxidation at low temperature. 相似文献
11.
With global climate change, ocean warming and acidification occur concomitantly. In this study, we tested the hypothesis that increasing CO 2 levels affect the acid–base balance and reduce the activity capacity of the Arctic spider crab Hyas araneus, especially at the limits of thermal tolerance. Crabs were acclimated to projected oceanic CO 2 levels for 12 days (today: 380, towards the year 2100: 750 and 1,120 and beyond: 3,000 μatm) and at two temperatures (1 and 4 °C). Effects of these treatments on the righting response (RR) were determined (1) at acclimation temperatures followed by (2) righting when exposed to an additional acute (15 min) heat stress at 12 °C. Prior to (resting) and after the consecutive stresses of combined righting activity and heat exposure, acid–base status and lactate contents were measured in the haemolymph. Under resting conditions, CO 2 caused a decrease in haemolymph pH and an increase in oxygen partial pressure. Despite some buffering via an accumulation of bicarbonate, the extracellular acidosis remained uncompensated at 1 °C, a trend exacerbated when animals were acclimated to 4 °C. The additional combined exposure to activity and heat had only a slight effect on blood gas and acid–base status. Righting activity in all crabs incubated at 1 and 4 °C was unaffected by elevated CO 2 levels or acute heat stress but was significantly reduced when both stressors acted synergistically. This impact was much stronger in the group acclimated at 1 °C where some individuals acclimated to high CO 2 levels stopped responding. Lactate only accumulated in the haemolymph after combined righting and heat stress. In the group acclimated to 1 °C, lactate content was highest under normocapnia and lowest at the highest CO 2 level in line with the finding that RR was largely reduced. In crabs acclimated to 4 °C, the RR was less affected by CO 2 such that activity caused lactate to increase with rising CO 2 levels. In line with the concept of oxygen and capacity limited thermal tolerance, all animals exposed to temperature extremes displayed a reduction in scope for performance, a trend exacerbated by increasing CO 2 levels. Additionally, the differences seen between cold- and warm-acclimated H. araneus after heat stress indicate that a small shift to higher acclimation temperatures also alleviates the response to temperature extremes, indicating a shift in the thermal tolerance window which reduces susceptibility to additional CO 2 exposure. 相似文献
12.
A new composite for water treatment was prepared by melt blend for oil and hexavalent chromium absorption. Ethylene Propylene
Diene Monomer (EPDM) was the matrix, calcinatory Fe 2O 3 and anion-exchange resin 201×7 were the fillers. This composite can suspend in water–oil contact (WOC) and absorb oils and
hexavalent chromium in wastewater simultaneously. The absorbencies of composites changed greatly with various ratios of calcinatory
Fe 2O 3 and anion-exchange resin 201×7. The results showed that the oil absorbencies increased continuously and hexavalent chromium
absorbencies were step-down as calcinatory Fe 2O 3 loadings from 13 to 19%. The composite can adsorb oils and hexavalent chromium simultaneously. The optimized proportion of
calcinatory Fe 2O 3 and anion-exchange resin 201×7 in composite was found when the absorbencies of oils and hexavalent chromium reaching the
maximum simultaneously. This composite is an inexpensive, convenient and high efficiency material for removing oils and hexavalent
chromium from wastewater. 相似文献
13.
Respiration rates and elemental composition (carbon and nitrogen) were determined for four dominant oncaeid copepods ( Triconia borealis, Triconia canadensis, Oncaea grossa and Oncaea parila) from 0–1,000 m depth in the western subarctic Pacific. Across the four species of which dry weight (DW) varied from 2.0
to 32 μg, respiration rates measured at in situ temperature (3°C) increased with DW, ranging from 0.84 to 7.4 nl O 2 individual −1 h −1. Carbon (C) and nitrogen (N) composition of the four oncaeid species ranged from 49–57% of DW and 7.0–10.3% of DW, respectively,
and the resultant C:N ratios were 4.8–8.3. The high C contents and C:N ratios were reflected by large accumulation of lipids
in their body. Specific respiration rates (SR, a fraction of body C respired per day) ranged between 0.5 and 1.3% day −1. Respiration rates adjusted to a body size of 1 mg body N (i.e. adjusted metabolic rates, AMR) of the four oncaeid species
[0.6–1.1 μl O 2 (mg body N) −0.8 h −1 at 3°C] were significantly lower than those (1.7–5.1) reported in the literature for oithonid and calanoid copepods at the
same temperature. The present results indicate that lower metabolic expenditure due to less active swimming (pseudopelagic
life mode) together with rich energy reserve in the body (as lipids) are the characters of oncaeid copepods inhabiting in
the epi- and mesopelagic zones of this region. 相似文献
14.
The purpose of the research was to study the behavior of lignin degradation under different conditions ( T 110–190°C, pO 2 0.5–1.5 MPa, pH 5, 9 and 12) and to develop a predictive model. Temperature increase improved lignin removal from 75% at
110°C to 100% at 190°C (experimental). Increasing the pH enhanced the lignin removal efficiency from 30 to 97% (experimental).
The developed model predicted the lignin degradation and changes in COD, BOD and TOC. The model agreed well with the experimental
data ( R
2 = 0.93 at pH 5 and 12). 相似文献
15.
Increasing atmospheric CO 2 equilibrates with surface seawater, elevating the concentration of aqueous hydrogen ions. This process, ocean acidification, is a future and contemporary concern for aquatic organisms, causing failures in Pacific oyster ( Crassostrea gigas) aquaculture. This experiment determines the effect of elevated pCO 2 on the early development of C. gigas larvae from a wild Pacific Northwest population. Adults were collected from Friday Harbor, Washington, USA (48°31.7′N, 12°1.1′W) and spawned in July 2011. Larvae were exposed to Ambient (400 μatm CO 2), MidCO 2 (700 μatm), or HighCO 2 (1,000 μatm). After 24 h, a greater proportion of larvae in the HighCO 2 treatment were calcified as compared to Ambient. This unexpected observation is attributed to increased metabolic rate coupled with sufficient energy resources. Oyster larvae raised at HighCO 2 showed evidence of a developmental delay by 3 days post-fertilization, which resulted in smaller larvae that were less calcified. 相似文献
16.
The kinetics of famotidine (FAM) transformation under the influence of various factors, important from the environmental point of view, was investigated in aqueous solutions. The degradation processes using UV, H 2O 2, UV/H 2O 2, H 2O 2/Fe 2+, and UV/H 2O 2/Fe 2+ were studied. Direct photolysis and H 2O 2-assisted photolysis showed a pseudo-first-order kinetics, while the Fenton and the photo-Fenton processes fit second-order kinetics. The provided experiments proved a high resistance of FAM to direct photolysis. Its stability depends highly on the pH of the reaction solutions. The rate of FAM direct photolysis in acidic solutions was almost negligible. The reaction rate of FAM photolysis at pH 8–9 was 3.7 × 10 ?3 min ?1 with DT 50 about 3 h 7 min. It was found that the presence of H 2O 2 in the reaction environment enhances the rate of photolysis of FAM. The observed rates of reaction were 5.1 × 10 ?3 min ?1 and 3.7 × 10 ?3 min ?1 in acidic and basic solutions, respectively. The used Fenton systems appeared to be the most efficient in FAM removal. The rate of reaction depends on concentration of Fe 2+ and H 2O 2. It was observed that the presence of UV-light enhances the reaction rate by two to six times in comparison to the classical Fenton system. Additionally, FAM behavior in natural water under solar irradiation was examined. The irradiation experiments were carried out in batch experiments with simulated sunlight. 相似文献
17.
Mechanisms that can influence the tolerance of hypoxia in brackish waters were studied in resting and fed crabs, Carcinus maenas, at 15?°C. Mortality, blood oxygenation, acid-base status and lactate concentration were analysed in fed crabs held in full-strength normoxic seawater (32.5‰?S) and then transferred for 24?h to a partial pressure of oxygen (P o2) of 3?kPa (1.4?mg?l ?1) and various salinities (17, 12.5, 10, 8‰?S). At salinity levels >10‰, fed crabs tolerated P o2 values as low as 3?kPa in the ambient water and 0.5?kPa in their arterial blood for 24?h without switching to anaerobic metabolism. Only below 10‰?S did their blood-lactate content rise, leading to their death despite the fact that their blood O 2-content was twice the control value measured in full-strength normoxic seawater and their blood P o2 did not decrease below values recorded at higher salinity levels. Addition of CO 2 to 8‰?S water (CO 2 partial pressure increasing from 0.1 to 0.3?kPa) decreased blood-lactate production and mortality, suggesting that at 10‰?S impairment of the O 2 supply is limited by an excessive blood O 2-affinity. The results are discussed in terms of the distribution (?10‰?S) of C. maenas along salinity gradients in estuaries and bays. 相似文献
18.
We investigated the impacts of warming and elevated pCO 2 on newly settled Amphibalanus improvisus from Kiel Fjord, an estuarine ecosystem characterized by significant natural pCO 2 variability. In two experiments, juvenile barnacles were maintained at two temperature and three pCO 2 levels (20/24 °C, 700–2,140 μatm) for 8 weeks in a batch culture and at four pCO 2 levels (20 °C, 620–2,870 μatm) for 12 weeks in a water flow-through system. Warming as well as elevated pCO 2 hardly affected growth or the condition index of barnacles, although some factor combinations led to temporal significances in enhanced or reduced growth with an increase in pCO 2. While warming increased the shell strength of A. improvisus individuals, elevated pCO 2 had only weak effects. We demonstrate a strong tolerance of juvenile A. improvisus to mean acidification levels of about 1,000 μatm pCO 2 as is already naturally experienced by the investigated barnacle population. 相似文献
19.
Changes in seawater carbonate chemistry that accompany ongoing ocean acidification have been found to affect calcification
processes in many marine invertebrates. In contrast to the response of most invertebrates, calcification rates increase in
the cephalopod Sepia officinalis during long-term exposure to elevated seawater pCO 2. The present trial investigated structural changes in the cuttlebones of S. officinalis calcified during 6 weeks of exposure to 615 Pa CO 2. Cuttlebone mass increased sevenfold over the course of the growth trail, reaching a mean value of 0.71 ± 0.15 g. Depending
on cuttlefish size (mantle lengths 44–56 mm), cuttlebones of CO 2-incubated individuals accreted 22–55% more CaCO 3 compared to controls at 64 Pa CO 2. However, the height of the CO 2-exposed cuttlebones was reduced. A decrease in spacing of the cuttlebone lamellae, from 384 ± 26 to 195 ± 38 μm, accounted
for the height reduction The greater CaCO 3 content of the CO 2-incubated cuttlebones can be attributed to an increase in thickness of the lamellar and pillar walls. Particularly, pillar
thickness increased from 2.6 ± 0.6 to 4.9 ± 2.2 μm. Interestingly, the incorporation of non-acid-soluble organic matrix (chitin)
in the cuttlebones of CO 2-exposed individuals was reduced by 30% on average. The apparent robustness of calcification processes in S. officinalis, and other powerful ion regulators such as decapod cructaceans, during exposure to elevated pCO 2 is predicated to be closely connected to the increased extracellular [HCO 3
−] maintained by these organisms to compensate extracellular pH. The potential negative impact of increased calcification in
the cuttlebone of S. officinalis is discussed with regard to its function as a lightweight and highly porous buoyancy regulation device. Further studies working
with lower seawater pCO 2 values are necessary to evaluate if the observed phenomenon is of ecological relevance. 相似文献
20.
Radon ( 222Rn) and carbon dioxide were monitored simultaneously in soil air under a cool-temperate deciduous stand on the campus of Hokkaido
University, Sapporo, Japan. Both 222Rn and CO 2 concentrations in soil air varied with atmospheric (soil) temperature in three seasons, except for winter when the temperature
in soil air remained constant at 2–3°C at depth of 80 cm. In winter, the gaseous components were influenced by low-pressure
region passing through the observation site when the ground surface was covered with snow of ~1 m thickness. Carbon isotopic
analyses of CO 2 suggested that CO 2 in soil air may result from mixing of atmospheric air and soil components of different origins, i.e. CO 2 from contemporary soil organic matter and old carbon from deeper source, to varying degrees, depending on seasonal meteorological
and thus biological conditions. 相似文献
|