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1.
The behavior of metal ions’ leaching and precipitated mineral phases of metal-rich fly ash (FA) was examined in order to evaluate
microbial impacts on carbon sequestration and metal immobilization. The leaching solutions consisted of aerobic deionized
water (DW) and artificial eutrophic water (AEW) that was anaerobic, organic- and mineral-rich, and higher salinity as is typical
of bottom water in eutrophic algae ponds. The Fe- and Ca-rich FAs were predominantly composed of quartz, mullite, portlandite,
calcite, hannebachite, maghemite, and hematite. After 86 days, only Fe and Ca contents exhibited a decrease in leaching solutions
while other major and trace elements showed increasing or steady trends in preference to the type of FA and leaching solution.
Ca-rich FA showed strong carbon sequestration efficiency ranging up to 32.3 g CO 2/kg FA after 86 days, corresponding to almost 65% of biotic carbon sequestration potential under some conditions. Variations
in the properties of FAs such as chemical compositions, mineral constituents as well as the type of leaching solution impacted
CO 2 capture. Even though the relative amount of calcite increased sixfold in the AEW and the relative amount of mineral phase
reached 37.3 wt% using Ca-rich FA for 86 days, chemical sequestration did not accomplish simultaneous precipitation and sequestration
of several heavy metals. 相似文献
2.
Rising levels of CO 2 in the atmosphere have led to increased CO 2 concentrations in the oceans. This enhanced carbon availability to the marine primary producers has the potential to change their nutrient stoichiometry, and higher carbon-to-nutrient ratios are expected. As a result, the quality of the primary producers as food for herbivores may change. Here, we present experimental work showing the effect of feeding Rhodomonas salina grown under different pCO 2 (200, 400 and 800 μatm) on the copepod Acartia tonsa. The rate of development of copepodites decreased with increasing CO 2 availability to the algae. The surplus carbon in the algae was excreted by the copepods, with younger stages (copepodites) excreting most of their surplus carbon through respiration and adult copepods excreting surplus carbon mostly as DOC. We consider the possible consequences of different excretory pathways for the ecosystem. A continued increase in the CO 2 availability for primary production, together with changes in the nutrient loading of coastal ecosystems, may cause changes in the trophic links between primary producers and herbivores. 相似文献
3.
This study, with FAOSTAT and Taiwan data sources, estimates Taiwan carbon dioxide (CO 2) emissions in harvested wood products (HWP) by applying the three accounting methods suggested by the 2006 IPCC Guidelines. The investigation also explores impulse responses of CO 2 emissions to economic factors. Results from FAOSTAT and Taiwan data demonstrate an inconsistent production approach (PA) in the signs of the estimated CO 2 emissions. Average contributions of HWP from 1990 to 2008 for the stock change approach (SCA), PA and atmospheric flow approach (AFA) in Taiwan are ?3.195 Tg, 0.412 Tg and 10.632 Tg CO 2 emissions, respectively. SCA has determined the Taiwan HWP as a carbon reservoir; in contrast, PA and AFA have determined Taiwan HWP as a CO 2 emission. The net forest products imports into Taiwan induce the inconsistent signs of HWP carbon sequestration among SCA, PA and AFA. The vector autoregressive model (VAR) results also indicate that real GDP per capita is crucial for SCA CO 2 emissions, followed by exchange rate. 相似文献
4.
Gypsum has been applied as a natural fertilizer and soil amendment for centuries in agriculture for providing crop nutrients such as Ca and S, and for improving soil physical properties. Recently, gypsum has been tested for sequestrating CO 2 from the air and for capturing soluble phosphates in the soil, through formation of insoluble calcium phosphates and carbonates. However, the environmental factors controlling these sequestration processes have not been systemically studied. Here, we calculate optimal conditions of sequestration using chemical equilibrium modeling. Our results show that CO 2 carbonation is effective at pH higher than 8.5 at atmospheric concentration. The removal of P is higher than 80 % for pH higher than 6.4, when Ca and P are at stoichiometric ratio. Also, placement of gypsum in subsoil is more effective for CO 2 capture than applying it on soil surface since soil pores often contain higher concentrations of CO 2 due to the soil respiration process. Overall, increases in medium pH, gypsum application rate, or CO 2 partial pressure can increase the effectiveness of the amendment. 相似文献
5.
Experiments in which organisms are reared in treatments simulating current and future pCO 2 concentrations are critical for ocean acidification (OA) research. The majority of OA exposure experiments use average atmospheric pCO 2 levels as a baseline treatment. We conducted an ecoregion-scale analysis of global carbon chemistry datasets. For many locales, atmospheric pCO 2 levels are not an appropriate characterization of marine carbon chemistry. We argue that atmospheric pCO 2 should be disregarded when setting baseline treatment conditions and experimental design should rely on measurements of carbon chemistry in a study subject’s habitat. As carbon chemistry conditions vary with space and time, we suggest using a range of pCO 2 values as a control rather than a single value. We illustrate this issue with data on the habitat of Euphausia pacifica, which currently lives in waters with a pCO 2 around 900 μatm, a concentration much higher than the current global atmospheric mean. 相似文献
6.
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
7.
The rates of photosynthesis and dark respiration for 7 marine algae and 1 fresh-water alga were measured and compared. The dinoflagellates Glenodinium sp. and zooxanthellae have high dark respiration rates relative to photosynthetic rates, which may decrease their net growth rates. Photorespiration in the 8 algal species was studied by examining the effects of the concentration of oxygen on the rates of photosynthesis, on the incorporation of 14CO 2 into the photorespiratory pathway intermediates glycine and serine, and on the postillumination burst of carbon dioxide production and oxygen consumption. A combination of these results indicates that all the algae tested can photorespire, but that Glenodinium sp., Thalassiosira pseudonana, and zooxanthellae either have a photorespiratory pathway different from that proposed for freshwater algae (Tolbert, 1974), or an additional pathway for glycolate metabolism. 相似文献
8.
Measuring the amount of fossil fuel carbon stored in the vegetation is now crucial to understand the mechanisms ruling climate
changes. In this respect, highly polluted areas such as major towns represent “natural” laboratories because fossil fuel CO 2 ( 14C-free) is isotopically distinct from mean atmospheric CO 2 ( 14C-labeled). Here, a 14C study of urban grasses near a major highway in Paris, France, shows that plants store up to 13% of fossil fuel carbon. The
14C composition of urban grasses is thus a novel parameter to assess the fossil fuel CO 2 pollution. 相似文献
9.
Carbonic anhydrase (CA, EC 4.2.1.1) activity was detected in 22 species of tropical cnidarians which contain endosymbiotic dinoflagellates (=zooxanthellae). CA activity was 2 to 3 times higher in animal tissue than in algae and ca. 29 times higher in zooxanthellate than azooxanthellate species. It was also higher in the zooxanthellate tentacle tissue than in the azooxanthellate column tissue of the anemone Condylactis gigantea. CA was therefore significantly related to the presence of endosymbiotic algae. Further results indicated that CA functions in the photosynthetic carbon metabolism of zooxanthellate cnidarians as evidenced by (1) low CA activity in shade-adapted and deep water colonies compared to the more productive shallow water, light-adapted colonies of the coral Stylophora pistillata, and (2) the 56 to 85% reduction in photosynthetic carbon assimilation by zooxanthellae in situ in the presence of Diamox, an inhibitor of CA. Although CA has been proposed to function in calcification, its association with zooxanthellae and photosynthetic activity in both calcifying and non-calcifying associations suggests a role in photosynthetic metabolism of algal/cnidarian symbioses. It is proposed that CA acts as a CO 2 supply mechanism by releasing CO 2 from bicarbonate, and enabling zooxanthellae to maintain high rates of photosynthesis in their intracellular environment. 相似文献
10.
In Life Cycle Assessment (LCA), carbon dioxide (CO 2) emissions from biomass combustion are traditionally assumed climate neutral if the bioenergy system is CO 2 flux neutral, i.e. the quantity of CO 2 released approximately equals the amount of CO 2 sequestered in biomass. This convention is a plausible assumption for fast growing biomass species, but is inappropriate for slower growing biomass, like forests. In this case, the climate impact from biomass combustion can be potentially underestimated if CO 2 emissions are ignored, or overestimated, if biogenic CO 2 is considered equal to anthropogenic CO 2. The estimation of the effective climate impact should take into account how the CO 2 fluxes are distributed over time: the emission of CO 2 from bioenergy approximately occurs at a single point in time, while the absorption by the new trees is spread over several decades. Our research target is to include this dynamic time dimension in unit-based impact analysis, using a boreal forest stand as case study. The boreal forest growth is modelled with an appropriate function, and is investigated under different forestry regimes (affecting the growth rate and the year of harvest). Specific atmospheric decay functions for biomass-derived CO 2 are then elaborated for selected combinations of forest management options. The contribution to global warming is finally quantified using the GWP bio index as climate metric. Results estimates the effects of these practices on the characterization factor used for the global warming potential of CO 2 from bioenergy, and point out the key role played by the selected time horizon. 相似文献
11.
Terrestrial CO 2 flux estimates are obtained from two fundamentally different methods generally termed bottom-up and top-down approaches. Inventory methods are one type of bottom-up approach which uses various sources of information such as crop production surveys and forest monitoring data to estimate the annual CO 2 flux at locations covering a study region. Top-down approaches are various types of atmospheric inversion methods which use CO 2 concentration measurements from monitoring towers and atmospheric transport models to estimate CO 2 flux over a study region. Both methods can also quantify the uncertainty associated with their estimates. Historically, these two approaches have produced estimates that differ considerably. The goal of this work is to construct a statistical model which sensibly combines estimates from the two approaches to produce a new estimate of CO 2 flux for our study region. The two approaches have complementary strengths and weaknesses, and our results show that certain aspects of the uncertainty associated with each of the approaches are greatly reduced by combining the methods. Our model is purposefully simple and designed to take the two approaches’ estimates and measures of uncertainty at ‘face value’. Specifically, we use a constrained least-squares approach to appropriately weigh the estimates by the inverse of their variance, and the constraint imposes agreement between the two sources. Our application involves nearly 18,000 flux estimates for the upper midwest United States. The constrained dependencies result in a non-sparse covariance matrix, but computation requires only minutes due to the structure of the model. 相似文献
12.
Land use change, natural disturbance, and climate change directly alter ecosystem productivity and carbon stock level. The estimation of ecosystem carbon dynamics depends on the quality of land cover change data and the effectiveness of the ecosystem models that represent the vegetation growth processes and disturbance effects. We used the Integrated Biosphere Simulator (IBIS) and a set of 30- to 60-m resolution fire and land cover change data to examine the carbon changes of California's forests, shrublands, and grasslands. Simulation results indicate that during 1951-2000, the net primary productivity (NPP) increased by 7%, from 72.2 to 77.1 Tg C yr −1 (1 teragram = 10 12 g), mainly due to CO 2 fertilization, since the climate hardly changed during this period. Similarly, heterotrophic respiration increased by 5%, from 69.4 to 73.1 Tg C yr −1, mainly due to increased forest soil carbon and temperature. Net ecosystem production (NEP) was highly variable in the 50-year period but on average equalled 3.0 Tg C yr −1 (total of 149 Tg C). As with NEP, the net biome production (NBP) was also highly variable but averaged −0.55 Tg C yr −1 (total of -27.3 Tg C) because NBP in the 1980s was very low (-5.34 Tg C yr −1). During the study period, a total of 126 Tg carbon were removed by logging and land use change, and 50 Tg carbon were directly removed by wildland fires. For carbon pools, the estimated total living upper canopy (tree) biomass decreased from 928 to 834 Tg C, and the understory (including shrub and grass) biomass increased from 59 to 63 Tg C. Soil carbon and dead biomass carbon increased from 1136 to 1197 Tg C.Our analyses suggest that both natural and human processes have significant influence on the carbon change in California. During 1951-2000, climate interannual variability was the key driving force for the large interannual changes of ecosystem carbon source and sink at the state level, while logging and fire were the dominant driving forces for carbon balances in several specific ecoregions. From a long-term perspective, CO 2 fertilization plays a key role in maintaining higher NPP. However, our study shows that the increase in C sequestration by CO 2 fertilization is largely offset by logging/land use change and wildland fires. 相似文献
13.
Mechanisms of photoadaptation of photosynthesis have been studied in three strains of the symbiotic dinoflagellate Symbiodinium microadriaticum. Algal strains isolated from the clam Tridacna maxima, the sea anemone Aiptasia pulchella, and the scleractinian coral Montipora verrucosa were maintained in the defined medium ASP-8A, and were grown at irradiances ranging from 22 to 248 μE m -2 s -1 on a 14 h:10 h (light:dark) photoperiod at 26°C. All algal cultures were analysed during log-phase of growth. At all light levels, rates of cell division and photosynthesis were determined, as were cell volumes, pigmentation (including chlorophyll a, chlorophyll c 2, peridinin, β-carotene and xanthophylls), and carbon and nitrogen content. Low light-induced changes in pigmentation were evident to varying degrees in all three algal strains, although alterations in the photosynthesis-irradiance relations were distinctly different in each strain. The algae from T. maxima show the least photoadaptive capability, and seem to photoadapt by changing photosynthetic unit (PSU) size. Algae from A. pulchella appear to adapt by changing PSU number, while algae from M. verrucosa appear to photoadapt by changes in the activities of CO 2-fixing enzymes or electron transport systems. These are the first observations that demonstrate functional differences in different strains of S. microadriaticum. The adaptive capabilities of the algae appear to correlate well with the ecological distribution of their respective hosts. The study was made from July 1981 through December 1982. 相似文献
14.
Echinoderms are major predators of anemones in temperate ecosystems. The fate of two algae, zooxanthellae and zoochlorellae, after their host anemone ( Anthopleura elegantissima Brandt) was consumed by the leather star Dermasterias imbricata Grube was determined in experiments conducted in July and August 2004. Productivity, photosynthetic pigments, and mitotic index (percent of cells dividing) were used as indicators of algal health; algae released after leather stars consumed their host were compared with algae freshly isolated from anemones. Two types of waste products contained algae: pellets resulting from extraoral digestion, and feces. Zooxanthellae and zoochlorellae isolated from these waste products were photosynthetic, although to different extents. For algae from feces and pellets, light-saturated photosynthetic rates ( P
max) were 85 and 13%, respectively, of P
max of freshly isolated zooxanthellae; and were 20 and 46%, respectively, for zoochlorellae. The photosynthetic pigments and mitotic index (percent of dividing cells) were not altered by the feeding activities of the leather star. These results show that algae released by seastar predation on their hosts remain viable, and are hence available for establishing symbioses in A. elegantissima and other potential hosts. 相似文献
15.
Ocean acidification (OA) and the biological consequences of altered seawater chemistry have emerged as a significant environmental
threat to healthy marine ecosystems. Because a more acidic ocean interferes with fixation of calcium carbonate to form shells
or calcified skeletons, future ocean chemistry may significantly alter the physiology of calcifying marine organisms. These
alterations may manifest themselves directly in the calcification process, or have synergistic effects with other environmental
factors such as elevated temperatures. New tools permit us to explore subtle changes in gene expression patterns in response
to environmental conditions. We raised sea urchins ( Strongylocentrotus franciscanus) under conditions simulating future atmospheric CO 2 levels of 540 and 970 ppm. When larvae raised under elevated CO 2 conditions were subjected to 1-h acute temperature stress, their ability to mount a physiological response (as measured by
expression of the molecular chaperone hsp70) was reduced relative to those raised under ambient CO 2 conditions. These results represent the first use of gene expression assays to study the effects of OA on sea urchin development.
They highlight the importance of looking at multiple environmental factors simultaneously as this approach may reveal previously
unsuspected biological impacts of atmospheric changes. 相似文献
16.
In the context of global warming and the energy crisis, emissions to the atmosphere of greenhouse gases such as carbon dioxide (CO2) and methane (CH4) should be reduced, and biomethane from landfill biogas should be recycled. For this, there is a need for affordable technologies to capture carbon dioxide, such as adsorption of biogas on activated carbon produced from industrial wastes. Here we converted glycerol, a largely available by-product from biodiesel production, into activated carbon with the first use of potassium acetate as an activating agent. We studied adsorption of CO2 and CH4 on activated carbon. The results show that activated carbon adsorb CO2 up to 20% activated carbon weight at 250 kPa, and 9% at atmospheric pressure. This is explained by high specific surface areas up to 1115 m2g−1. Moreover, selectivity values up to 10.6 are observed for the separation of CO2/CH4. We also found that the equivalent CO2 emissions from activated carbon synthesis are easily neutralized by their use, even in a small biogas production unit. 相似文献
17.
Ecosystem functioning is intimately linked to its physical environment by complex two-way interactions. These two-way interactions arise because vegetation both responds to the external environment and actively regulates its micro-environment. By altering stomatal aperture, and therefore the transpiration rate, plants modify soil moisture and atmospheric humidity and these same physical variables, in return, modify stomatal conductance. Relationships between biotic and abiotic components are particularly strong in closed, managed environments such as greenhouses and growth chambers, which are used extensively to investigate ecosystem responses to climatic drivers. Model-assisted designs that account for the physiological dynamics governing two-way interactions between biotic and abiotic components are absent from many ecological studies. Here, a general model of the vegetation-atmosphere system in closed environments is proposed. The model accounts for the linked carbon-water physiology, the turbulent transport processes, and the energy and radiative transfer within the vegetation. Leaf gas exchange is modeled using a carbon gain optimization approach that is coupled to leaf energy balance. The turbulent transport within the canopy is modeled in two-dimensions using first-order closure principles. The model is applied to the Lysimeter CO 2 Gradient (LYCOG) facility, wherein a continuous gradient of atmospheric CO 2 is maintained on grassland assemblages using an elongated chamber where the micro-climate is regulated by variation in air flow rates. The model is employed to investigate how species composition, climatic conditions, and the imposed air flow rate affect the CO 2 concentration gradient within the LYCOG and the canopy micro-climate. The sensitivity of the model to key physiological and climatic parameters allows it to be used not only to manage current experiments, but also to formulate novel ecological hypotheses (e.g., by modeling climatic regimes not currently employed in LYCOG) and suggest alternative experimental designs and operational strategies for such facilities. 相似文献
18.
Population growth and social/technological developments have resulted in the buildup of carbon dioxide (CO 2) in the atmosphere and oceans to the extent that we now see changes in the earth’s climate and ocean chemistry. Ocean acidification is one consequence of these changes, and it is known with certainty that it will continue to increase as we emit more CO 2 into the atmosphere. Ocean acidification is a global issue likely to impact marine organisms, food webs and ecosystems and to be most severely experienced by the people who depend on the goods and services the ocean provides at regional and local levels. However, research is in its infancy and the available data on biological impacts are complex (e.g., species-specific response). Educating future generations on the certainties and uncertainties of the emerging science of ocean acidification and its complex consequences for marine species and ecosystems can provide insights that will help assessing the need to mitigate and/or adapt to future global change. This article aims to present different educational approaches, the different material available and highlight the future challenges of ocean acidification education for both educators and marine biologists. 相似文献
19.
An automatically operated method for high precision measurements of steady-state photosynthesis by macroalgae was developed. Changes in pH and oxygen content of seawater passing the algae in a flowthrough system, could be measured with extremely high accuracy over very long periods of time. The method is especially suitable for measurements on flowthrough systems with high rates of water exchanges (i.e. short retention time), and can be used to study exchange processes for marine plants, animals and small ecosystems. Since the same measuring unit is used for several flowthrough chambers, the method is very suitable for comparisons between different species, or between differently pretreated specimens of the same species (e.g. in toxicological studies). The method was used to study the ratio: [oxygen production] to [CO 2+H + uptake] at different light intensities for several macroalgae belonging to different systematic groups and from different habitats. At lower photosynthetic rates this ratio was similar for all of the algae studied (1.17±0.02). For brown algae of the fucacean family, the ratio increased by 0.08 units at higher photosynthetic rates. This increase was thought to be related to the crassulacean acid metabolism (CAM)-like strategies connected to these algae. For all other algae studied, the ratio remained constant or decreased slightly (at most by 0.04 units) at higher photosynthetic rates. The relations between the abovementioned ratio and the photosynthetic quotient are discussed on a theoretical basis. 相似文献
20.
Intertidal macroalgae may spend a significant part of their lives in air. During photosynthesis in air, they encounter much
lower concentrations of inorganic carbon than in seawater. Because they accumulate inorganic carbon from seawater, we investigated
whether they similarly accumulate it from air. We measured photosynthesis in the intertidal species Fucus vesiculosus L. during 1990 and 1991 with a gas-phase O 2 electrode or CO 2-exchange apparatus in air and with a liquid-phase O 2 electrode in seawater. Maximum rates were rapid and similar in air and seawater regardless of the method. Tissue from seawater
could carry on photosynthesis in CO 2-free air, indicating that carbon was stored in the tissue. After 2 h, this store was depleted and photosynthesis ceased.
Supplying CO 2 in air replenished the store. Under identical conditions, terrestrial C 3 and C 4 species showed no evidence of this store, but a CAM (crassulacean acid metabolism) species did. However, in contrast to the
CAM behavior, F. vesiculosus did not store CO 2 significantly in the dark. We found a small acid-releasable pool of carbon in the tissue that disappeared as photosynthesis
depleted the carbon store. However, the pool was too small to account for the total carbon stored. While CO 2 was being acquired or released from the store in the light, photosynthesis was not inhibited by 21% O 2. These results indicate that there are two parallel paths for the supply of CO 2 to photosynthesis. The first depends on inorganic carbon in seawater or in air and supports rapid photosynthesis. The second
involves CO 2 slowly released from an organic intermediate. The release protects CO 2 fixation from the inhibitory effects of 21% O 2. Photosynthesis in F. vesiculosus thus appears to be C 3-like in its rapid fixation of CO 2 from a small inorganic pool into phosphoglycerate. However, it is C 4-like in its pre-fixation of carbon in an organic pool in the light, and is CAM-like in its ability to slowly use this pool
as a sole source of CO 2. The organic pool may serve to protect photosynthetic CO 2 fixation against the inhibitory effects of O 2 in air and in the boundary layer in seawater.
Received: 6 March 1998 / Accepted: 16 October 1998 相似文献
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