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1.
Earthworms modify the soil environment through their feeding, casting, and burrowing activities, which may lead to more decomposition
and respiration in aerobic microsites and more denitrification in anaerobic microsites. The objective of this study was to
determine whether earthworms increase CO 2 and N 2O fluxes from an unfertilized corn agroecosystem. Earthworm populations within field enclosures (2.9 m 2) were reduced by repeatedly applying carbaryl insecticide, then single and mixed populations of Lumbricus terrestris L. and Aporrectodea caliginosa (Savigny) were added. Gas samples were collected once a week for 14 weeks, from June to September 2005. Carbaryl applications
reduced, but did not eliminate earthworms from enclosures. The CO 2 and N 2O fluxes were affected by the sampling date, with peak gas fluxes after rainfall events. Mean CO 2 and N 2O fluxes during the study period tended to be greater from enclosures with added earthworms than the control (no earthworms
added), but were not significantly affected by earthworm treatments due to the low survival rate of introduced earthworms.
Better control of earthworm populations in the field is required to fully assess the impact of earthworms on CO 2 and N 2O fluxes from temperate agroecosystems. 相似文献
2.
Although the Midwestern United States is one of the world's major agricultural production areas, few studies have assessed the effects of the region's predominant tillage and rotation practices on greenhouse gas emissions from the soil surface. Our objectives were to (a) assess short-term chisel (CP) and moldboard plow (MP) effects on soil CO 2 and CH 4 fluxes relative to no-till (NT) and, (b) determine how tillage and rotation interactions affect seasonal gas emissions in continuous corn and corn–soybean rotations on a poorly drained Chalmers silty clay loam (Typic Endoaquoll) in Indiana. The field experiment itself began in 1975. Short-term gas emissions were measured immediately before, and at increasing hourly intervals following primary tillage in the fall of 2004, and after secondary tillage in the spring of 2005, for up to 168 h. To quantify treatment effects on seasonal emissions, gas fluxes were measured at weekly or biweekly intervals for up to 14 sampling dates in the growing season for corn. Both CO 2 and CH 4 emissions were significantly affected by tillage but not by rotation in the short-term following tillage, and by rotation during the growing season. Soil temperature and moisture conditions in the surface 10 cm were significantly related to CO 2 emissions, although the proportion of variation explained by temperature and moisture was generally very low (never exceeded 27%) and varied with the tillage system being measured. In the short-term, CO 2 emissions were significantly higher for CP than MP and NT. Similarly, mean seasonal CO 2 emissions during the 2-year period were higher for CP (6.2 Mg CO 2-C ha −1 year −1) than for MP (5.9 Mg CO 2-C ha −1 year −1) and NT (5.7 Mg CO 2-C ha −1 year −1). Both CP and MP resulted in low net CH 4 uptake (7.6 and 2.4 kg CH 4-C ha −1 year −1, respectively) while NT resulted in net emissions of 7.7 kg CH 4-C ha −1 year −1. Mean emissions of CO 2 were 16% higher from continuous corn than from rotation corn during the two growing seasons. After 3 decades of consistent tillage and crop rotation management for corn and soybean producing grain yields well above average in the Midwest, continuous NT production in the corn–soybean rotation was identified as the system with the least soil-derived C emissions to the atmosphere from among those evaluated prior to and during corn production. 相似文献
3.
The surface of dryland soils is frequently characterised by a biological crust comprising of various combinations of cyanobacteria, algae, moss and lichens. In the Kalahari of Botswana, soil crusts are predominantly made up of cyanobacteria, which when moist, are capable of fixing N and C. Many cyanobacteria also produce extracellular polymeric substances (EPS) which bind soil particles together and decrease erodibility. The physical integrity and metabolic activity of soil crusts is thus critical to ecological productivity, erodibility and CO 2 fluxes in dryland regions. There are, however, few studies of the magnitude and controlling factors of soil CO 2 flux within these systems. Our aim was to quantify in situ soil CO2 flux during contrasting antecedent moisture conditions in the south west Kalahari of Botswana. We have designed a gas exchange chamber for field deployment coupled to a portable gas chromatograph, control and data logging instrumentation. The optical and active thermal control specifications of the chamber have been designed to permit photosynthesis and cope with the temperature extremes of the Kalahari whilst minimizing disturbance to the cyanobacteria soil crust. This approach has enabled CO2 fluxes to be monitored in situ with a high degree of precision for extended periods. In August 2005, when the surface and subsoils were dry, the ambient CO2 efflux was negative and low during the daytime (−6.15 mg C m2 h−1). When 8 mm rainfall equivalent of water was added to the surface there was an immediate uptake of CO2 during the daytime at rates up to 75 mg C m2 h−1 demonstrating that rates of net photosynthesis are greatly enhanced by available moisture. In contrast, in May 2006 following a prolonged wet period when the subsoil was moist, there was a net positive efflux of CO2 from the soil at rates of up to 60 mg C m2 h−1 irrespective of whether the surface soil was moist or not. This is consistent with subsoil heterotrophic bacterial respiration becoming an important contributor to soil efflux. 相似文献
4.
Net carbon dioxide (CO 2) emission from soils is controlled by the input rate of organic material and the rate of decomposition which in turn are affected by temperature, moisture and soil factors. While the relationships between CO 2 emission and soil factors are well-studied in non-salt-affected soils, little is known about soil properties controlling CO 2 emission from salt-affected soils. To close this knowledge gap, non-salt-affected and salt-affected soils (0-0.30 m) were collected from two agricultural regions: in India (irrigation induced salinity) and in Australia (salinity associated with ground water or non-ground water associated salinity). A subset (50 Indian and 70 Australian soils) covering the range of electrical conductivity (EC) and sodium adsorption ratio (SAR) in each region was used in a laboratory incubation experiment. The soils were left unamended or amended with mature wheat residues (2% w/w) and CO 2 release was measured over 120 days at constant temperature and soil water content. Residues were added to overcome carbon limitation for soil respiration. For the unamended soils, separation in multidimensional scaling plots was a function of differences in soil texture (clay, sand), SOC pools (particulate organic carbon (POC) and humus-C) and also EC. Cumulative CO 2-C emission from unamended and amended soils was related to soil properties by stepwise regression models. Cumulative CO 2-C emission was negatively correlated with EC in saline soils ( R2 = 0.50, p < 0.05) from both regions. In the unamended non-salt-affected soils, cumulative CO 2-C emission was significantly positively related to the content of POC for the Indian soils and negatively related to clay content for the Australian soils. In the wheat residue amended soils, cumulative CO 2-C emission had positive relationship with POC and humus-C but a negative correlation with EC for both Indian and Australian soils. SAR was negatively related ( β = −0.66, p < 0.05) with cumulative CO 2-C emission only for the unamended saline-sodic soils of Australia. Cumulative CO 2-C emission was significantly negatively correlated with bulk density in amended soils from both regions. The study showed that in salt-affected soils, EC was the main factor influencing for soil respiration but the content of POC, humus-C and clay were also influential with the magnitude of influence depending on whether the soils were salt affected or not. 相似文献
5.
Potential effects of earthworms ( Lumbricus terrestris L.) inoculated into soil on fluxes of CO 2, CH 4 and N 2O were investigated for an untreated and a limed soil under beech in open topsoil columns under field conditions for 120 days.
Gas fluxes from L. terrestris, beech litter and mineral soil from soil columns were measured separately in jars at 17 °C. The inoculation with L. terrestris and the application of lime had no effect on cumulative CO 2 emissions from soil. During the first 3–4 weeks earthworms significantly ( P<0.05) increased CO 2 emissions by 16% to 28%. In contrast, significantly lower ( P<0.05) CO 2 emission rates were measured after 11 weeks. The data suggest that earthworm activity was high during the first weeks due
to the creation of burrows and incorporation of beech litter into the mineral soil. Low cumulative CH 4 oxidation rates were found in all soil columns as a result of CH 4 production and oxidation processes. L. terrestris with fresh feces and the beech litter produced CH 4 during the laboratory incubation, whereas the mineral soil oxidised atmospheric CH 4. Inoculation with L. terrestris led to a significant reduction ( P<0.02) in the CH 4 oxidation rate of soil, i.e. 53% reduction. Liming had no effect on cumulative CH 4 oxidation rates of soil columns and on CH 4 fluxes during the laboratory incubation. L. terrestris significantly increased ( P<0.001) cumulative N 2O emissions of unlimed soil columns by 57%. The separate incubation of L. terrestris with fresh feces resulted in rather high N 2O emissions, but the rate strongly decreased from 54 to 2 μg N kg –1 (dry weight) h –1 during the 100 h of incubation. Liming had a marked effect on N 2O formation and significantly ( P<0.001) reduced cumulative N 2O emissions by 34%. Although the interaction of liming and L. terrestris was not significant, N 2O emissions of limed soil columns with L. terrestris were 8% lower than those of the control.
Received: 2 September 1999 相似文献
6.
The effect of carbon dioxide partial preassure on the stability of iron chelates in calcareous soils is often laid aside. Theoretical stability diagrams have been developed showing the large importance of this compound on total iron solubility from Fe‐EDTA and ‐DTPA chelates. As CO 2 increases free Ca 2+ activity in solution decreases. Then chelation of iron increases. CO 2 partial preassure does not change the stability of Fe‐EDDHA since percentage of chelation is 100% in all conditions tested for this chelate. Experimental data fit theoretical diagrams well when CO 2 partial preassure is high, but when CO 2 ‐free air is used, chelation is greater than expected. Causes that can produce this difference are discussed. 相似文献
7.
There are no reports on the effects of elevated carbon dioxide [CO 2] on the fluxes of N 2O, CO 2 and CH 4 from semi-arid wheat cropping systems. These three soil gas fluxes were measured using closed chambers under ambient (420 ± 18 μmol mol −1) and elevated (565 ± 37 μmol mol −1) at the Free-Air Carbon dioxide Enrichment experimental facility in northern China. Measurements were made over five weeks on a wheat crop ( Triticum aestivum L. cv. Zhongmai 175). Elevated [CO 2] increased N 2O and CO 2 emission from soil by 60% and 15%, respectively, but had no significant effect on CH 4 flux. There was no significant interaction between [CO 2] and N application rate on these gas fluxes, probably because soil N was not limiting. At least 22% increase in C storage is required to offset the observed increase in greenhouse gas emissions under elevated [CO 2]. 相似文献
8.
以华北平原冬小麦农田尺度为研究对象,采用涡度相关技术,研究冬小麦灌浆期瞬态CO2通量日变化特征及其与农田热量平衡各分量的关系。结果表明,非水分胁迫下CO2通量日变化(负值表示通量指向冠层)为U型,群体净光合速率最高值为-1.2~-1.4mg/m2.s,夜间瞬态CO2通量呈非稳定变化,最高值达0.4~0.54mg/m2.s。白天时段内CO2通量与净辐射、潜热通量呈高度相关,8:00~15:30时段内CO2和水汽通量呈同步日变化趋势,水分利用效率处于稳定状态,瞬态水分利用效率基本维持在0.012~0.014g(CO2)/g(H2O)范围内;但早晨和傍晚时段内水分利用效率变化较大。 相似文献
9.
Although elevation of CO 2 has been reported to impact soil microbial functions, little information is available on the spatial and temporal variation of this effect. The objective of this study was to determine the microbial response in a northern Colorado shortgrass steppe to a 5-year elevation of atmospheric CO 2 as well as the reversibility of the microbial response during a period of several months after shutting off the CO 2 amendment. The experiment was comprised of nine experimental plots: three chambered plots maintained at ambient CO 2 levels of 360 μmol mol −1 (ambient treatment), three chambered plots maintained at 720 μmol mol −1 CO 2 (elevated treatment) and three unchambered plots of equal ground area used as controls to monitor the chamber effect.Elevated CO 2 induced mainly an increase of enzyme activities (protease, xylanase, invertase, alkaline phosphatase, arylsulfatase) in the upper 5 cm of the soil and did not change microbial biomass in the soil profile. Since rhizodeposition and newly formed roots enlarged the pool of easily available substrates mainly in the upper soil layers, enzyme regulation (production and activity) rather than shifts in microbial abundance was the driving factor for higher enzyme activities in the upper soil. Repeated soil sampling during the third to fifth year of the experiment revealed an enhancement of enzyme activities which varied in the range of 20-80%. Discriminant analysis including all microbiological properties revealed that the enzyme pattern in 1999 and 2000 was dominated by the CO 2 and chamber effect, while in 2001 the influence of elevated CO 2 increased and the chamber effect decreased.Although microbial biomass did not show any response to elevated CO 2 during the main experiment, a significant increase of soil microbial N was detected as a post-treatment effect probably due to lower nutrient (nitrogen) competition between microorganisms and plants in this N-limited ecosystem. Whereas most enzyme activities showed a significant post-CO 2 effect in spring 2002 (following the conclusion of CO 2 enrichment the previous autumn, 2001), selective depletion of substrates is speculated to be the cause for non-significant treatment effects of most enzyme activities later in summer and autumn, 2002. Therefore, additional belowground carbon input mainly entered the fast cycling carbon pool and contributed little to long-term carbon storage in the semi-arid grassland. 相似文献
10.
Free air carbon dioxide enrichment (FACE) systems rely primarily on wind to distribute CO 2 across treatment plots. Most current FACE designs inject CO 2 at the perimeter of the plot, and low wind speeds can result in large horizontal gradients of CO 2 concentration. These gradients can be reduced by using blowers to inject CO 2 or a mixture of CO 2 and air into the plot, but this process can alter the microclimate enough to affect plant growth. This report describes a new FACE system in which CO 2 emitters are evenly distributed across a plot in a square array to provide an area-source of CO 2. A variable mixture of CO 2 and air is supplied continuously to each emitter at a constant low total volume flow. Tests in 13 m 2 plots of grassland and maize using set points of 1.4 times the ambient concentration showed good horizontal uniformity of CO 2 concentration except for a small radius around each emitter. Temporal variation in CO 2 concentration in the daytime at canopy height at the center of the plot was similar to that of other FACE designs, with 1 min average CO 2 concentrations within 10% of the target 86% of the time. At night, the CO 2 concentration achieved was more variable, but 1 min averages of CO 2 concentration were within 20% of the target 83% of the time. The frequency distribution of instantaneous measurements made with an open path CO 2 analyzer indicated a distribution strongly skewed toward low concentrations compared with the 1 min averages, which literature suggests may be a general characteristic of FACE systems. Canopy air temperatures on nights with low wind differed by less than 0.1 °C in plots with and without flow to the emitters, indicating minimal disturbance of the canopy microclimate. A square array FACE system could be scaled to any horizontal dimension without compromising the horizontal uniformity of CO 2 concentration, and could be useful in large-scale screening of germplasm for CO 2 responsiveness under field conditions. 相似文献
11.
Wood ash has been used to alleviate nutrient deficiencies and acidification in boreal forest soils. However, ash and nitrogen (N) fertilization may affect microbial processes producing or consuming greenhouse gases: methane (CH 4), nitrous oxide (N 2O) and carbon dioxide (CO 2). Ash and N fertilization can stimulate nitrification and denitrification and, therefore, increase N 2O emission and suppress CH 4 uptake rate. Ash may also stimulate microbial respiration thereby enhancing CO 2 emission. The fluxes of CH 4, N 2O and CO 2 were measured in a boreal spruce forest soil treated with wood ash and/or N (ammonium nitrate) during three growing seasons. In addition to in situ measurements, CH 4 oxidation potential, CO 2 production, net nitrification and N 2O production were studied in laboratory incubations. The mean in situ N 2O emissions and in situ CO 2 production from the untreated, N, ash and ash + N treatments were not significantly different, ranging from 11 to 17 μg N 2O m ?2 h ?1 and from 533 to 611 mg CO 2 m ?2 h ?1. However, ash increased the CH 4 oxidation in a forest soil profile which could be seen both in the laboratory experiments and in the CH 4 uptake rates in situ. The mean in situ CH 4 uptake rate in the untreated, N, ash and ash + N plots were 153 ± 5, 123 ± 8, 188 ± 10 and 178 ± 18 μg m ?2 h ?1, respectively. 相似文献
12.
Field evolution of CH 4 and CO 2 from soils under four dominant land uses in the Mardi watershed, western Nepal, were monitored at 15-day intervals for 1 year using closed chamber techniques. The CH 4 oxidation rate (mean±SE, g CH 4 m –2 h –1) in the forest (22.8±6) was significantly higher than under grazing land (14±2) and an upland rainfed maize and millet system (Bari) (2.6±0.9). Irrigated rice fields (Khet) showed an oxidation rate of 6±0.8 g CH 4 m –2 h –1 in the dry season (December–May) but emitted a mean rate of 131 g CH 4 m –2 h –1 in the rainy season and autumn (June–October). The evolution of CO 2 ranged from 10 mg CO 2 m –2 h –1 in the Bari in January to 1,610 mg CO 2 m –2 h –1 in the forest in July. Higher evolution of CO 2 (mean±SE, mg CO 2 m –2 h –1) was observed in the Bari (399±39) and forest (357±36) compared to Khet (246±25) and grazing (206±20) lands. The annual emission of CO 2 evolution varied from 86.6 to 1,836 g CO 2 m –2 year –1. The activation energy for CH 4 and CO 2 varied between 16–283 and 80–117 kJ mol –1, respectively. The estimated temperature coefficient for CO 2 emission varied from 2.5 to 5.0. Temperature explained 46–51% of the variation in CO 2 evolution, whereas it explained only 4–36% of the variation in CH 4 evolution. 相似文献
13.
Warland and Thurtell (2000) proposed an analytical dispersion Lagrangian analysis (hereafter WT analysis) to relate the mean scalar concentration field to source profiles inside the canopy. The first objective of this study was to evaluate the performance of the WT analysis with existing turbulence statistics parameterizations in a corn canopy, by comparing its inferred net ecosystem CO 2 exchange (NEE) and latent heat flux ( λE) with eddy covariance measurements. The second objective was to assess the performance of the WT analysis to infer the soil CO 2 flux. Four parameterizations of turbulence statistics were used to estimate Lagrangian time scale ( TL) and standard deviation of vertical wind velocity ( σw) profiles. The estimated TL and σw profiles were then corrected for atmospheric stability conditions. The field experiment was carried out in a corn field from August to October 2007 and 2008. Profiles of water vapour and CO 2 mixing ratios were measured using a multiport sampling system connected to an infrared gas analyzer. Wind velocity within and above the canopy and eddy covariance measurements over the canopy were taken. The soil respiration, estimated using the WT analysis, was compared to estimates obtained by an empirical model. WT analysis fluxes showed good correlation ( R2 = 0.77-0.88) with NEE and λE obtained by the eddy covariance technique, but overestimated net fluxes, especially when corrections for atmospheric stability were applied. The optimization of TL and σw profiles using in-canopy turbulence measurements improved the agreement between measured and modeled NEE and λE. Inferred soil CO 2 fluxes were underestimated and were poorly correlated ( R2 = 0.02-0.01) with estimates obtained using an empirical model based on soil temperature. This poor performance in estimating the soil respiration is likely caused by the decoupling between inside and above canopy flows. 相似文献
14.
Enhancement of soil organic carbon (SOC) stocks through mulching has been proposed, and although this practice can alter several soil properties, its impact on the temporal variability of carbon dioxide (CO 2) emission from soils has not been widely investigated. To that end, we monitored CO 2 fluxes from a central Ohio Luvisol (fine, mixed, mesic Aeric Ochraqualf) amended with wheat ( Triticum aestivum L.) straw applied at rates of 0 (M0), 8 (M8) and 16 (M16) Mg dry matter ha −1 per year and supplemented with fertilizer (244 kg N ha −1 per year) or without. The experimental design was a randomized complete block design with three replications. The intensity of CO 2 emission was higher in the late winter (mean: 2.79 g CO 2-C m −2 per day) and summer seasons (2.45 g CO 2-C m −2 per day) and lowest in the autumn (1.34 g CO 2-C m −2 per day). While no significant effect of N fertilization on CO 2 emission was detected, soil mulching had a significant effect on the seasonal variation of CO 2 fluxes. The percentage of annual CO 2 emitted during the winter and spring was similar across treatments (17–22%); however, 43% of the annual CO 2 loss in the M0 plots occurred during the summer as opposed to 26% in the mulch treatments. A close relationship ( F=0.47 X+4.45, R2=0.97, P<0.001) was found between annual CO 2 flux ( F, Mg CO 2-C ha −1) and residue-C input ( X, Mg C ha −1). Litter and undecomposed residue amounted to 0.32 and 0.67 Mg C ha −1 per year in the M8 and M16 plots, respectively. After 4 years of straw application, SOC stocks (0–10 cm) were 19.6, 25.6 and 26.5 Mg C ha −1 in the M0, M8 and M16 treatments, respectively. The results show that soil mulching has beneficial effect on SOC sequestration and strongly influence the temporal pattern of CO 2 emission from soils. 相似文献
15.
We investigated the daily exchange of CO 2 between undisturbed Larix gmelinii (Rupr.) Rupr. forest and the atmosphere at a remote Siberian site during July and August of 1993. Our goal was to measure and partition total CO 2 exchanges into aboveground and belowground components by measuring forest and understory eddy and storage fluxes and then to determine the relationships between the environmental factors and these observations of ecosystem metabolism. Maximum net CO 2 uptake of the forest ecosystem was extremely low compared to the forests elsewhere, reaching a peak of only ∼5 μmol m −2 s −1 late in the morning. Net ecosystem CO 2 uptake increased with increasing photosynthetically active photon flux density (PPFD) and decreased as the atmospheric water vapor saturation deficit ( D) increased. Daytime ecosystem CO 2 uptake increased immediately after rain and declined sharply after about six days of drought. Ecosystem respiration at night averaged ∼2.4 μmol m −2 s −1 with about 40% of this coming from the forest floor (roots and heterotrophs). The relationship between the understory eddy flux and soil temperature at 5 cm followed an Arrhenius model, increasing exponentially with temperature (Q 10∼2.3) so that on hot summer afternoons the ecosystem became a source of CO 2. Tree canopy CO 2 exchange was calculated as the difference between above and below canopy eddy flux. Canopy uptake saturated at ∼6 μmol CO 2 m −2 s −1 for a PPFD above 500 μmol m −2 s −1 and decreased with increasing D. The optimal stomatal control model of Mäkelä et al. (1996) was used as a `big leaf' canopy model with parameter values determined by the non-linear least squares. The model accurately simulated the response of the forest to light, saturation deficit and drought. The precision of the model was such that the daily pattern of residuals between modeled and measured forest exchange reproduced the component storage flux. The model and independent leaf-level measurements suggest that the marginal water cost of plant C gain in Larix gmelinii is more similar to values from deciduous or desert species than other boreal forests. During the middle of the summer, the L. gmelinii forest ecosystem is generally a net sink for CO 2, storing ∼0.75 g C m −2 d −1. 相似文献
16.
The accelerated greenhouse effect and the degradation of land resources by water and wind erosion are two major, yet interrelated global environmental challenges. Accelerated decomposition of soil organic carbon (SOC) in cultivated soils results in decline in SOC stocks over time and also contributes to increased levels of CO 2 in the atmosphere. Off‐site transport of SOC in runoff waters during erosional events also contributes to SOC depletion, but there is a paucity of data in the literature documenting erosional SOC losses and the fate of eroded SOC. In this paper, we present a mass balance approach to compute CO 2 evolved from mineralization of SOC during transport and deposition of eroded soils. Erosion‐induced CO 2 emission rates ranging between 6 and 52 g C m −2 yr −1 were computed using data on SOC stocks and dynamics from a series of long‐term experiments conducted across a range of ecological regions. For the cropland of the world, we estimated an annual flux of 0.37 Pg CO 2‐C to the atmosphere due to water erosion. This flux is significant and suggests that water erosion must be taken into consideration when constructing global and regional C budgets. Through its contribution to atmospheric CO 2 increase, water erosion can have a positive feedback on the accelerated greenhouse effect. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
17.
Summary The effects of single and successive additions of Cd, Ni, and Zn on CO 2 evolution and dehydrogenase activity in a sandy luvisol were investigated in batch experiments under laboratory conditions. Successive additions of Cd, Ni, and Zn inhibited soil respiration relatively more than single doses, even before the same amount of metals had been added. In general, split additions of all metals reduced dehydrogenase activities in all soils to a lesser degree until the 28th day. Thereafter both modes of metal addition had the same effects throughout although the last successive addition was added on the 35th day. It is assumed that the relatively greater effect, especially on CO 2 evolution, of successive additions during the first period was due to short-term increases metal concentrations in the soil solution after each application. 相似文献
18.
Journal of Soils and Sediments - Understanding the effect of biochar on surface albedo and soil CO2 fluxes is a crucial issue in evaluating the impact of biochar on carbon sequestration and... 相似文献
19.
超临界CO2干燥是一种新型的干燥技术。为掌握罗非鱼片的超临界CO2干燥特性,该文研究了温度、压力和CO2流量对罗非鱼片的超临界CO2干燥动力学的影响规律,拟合了干燥曲线方程。结果表明:温度(35~55℃)对超临界CO2干燥过程有显著影响,而压力(15~35MPa)和CO2流量(15~35L/h)对干燥过程的影响相对较小;干燥方程符合Page模型。研究结果可为罗非鱼片的超临界CO2干制工业化生产和控制提供参考。 相似文献
20.
Model–data fusion is defined as matching model prediction and observations by varying model parameters or states using statistical estimation. In this paper, we review the history of applications of various model–data fusion techniques in studies of terrestrial carbon fluxes in two approaches: top-down approaches that use measurements of global CO 2 concentration and sometimes other atmospheric constituents to infer carbon fluxes from the land surface, and bottom-up approaches that estimate carbon fluxes using process-based models. We consider applications of model–data fusion in flux estimation, parameter estimation, model error analysis, experimental design and forecasting. Significant progress has been made by systematically studying the discrepancies between the predictions by different models and observations. As a result, some major controversies in global carbon cycle studies have been resolved, robust estimates of continental and global carbon fluxes over the last two decades have been obtained, and major deficiencies in the atmospheric models for tracer transport have been identified. In the bottom-up approaches, various optimization techniques have been used for a range of process-based models. Model–data fusion techniques have been successfully used to improve model predictions, and quantify the information content of carbon flux measurements and identify what other measurements are needed to further constrain model predictions. However, we found that very few studies in both top-down and bottom-up approaches have quantified the errors in the observations, model parameters and model structure systematically and consistently. We therefore suggest that future research will focus on developing an integrated Bayesian framework to study both model and measurement errors systematically. 相似文献
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