Functional Group Approach Research Articles

Ecological evaluation of weir removal based on physical habitat simulations for macroinvertebrate community

In Korea, rapid urbanization has changed the land use in rural areas, which has resulted in an increase in the number of weirs that are left untended in streams. Previously, changes in stream morphology and fishes were studied following the removal of such weirs. The present study was conducted to investigate changes in the habitat of the macroinvertebrate community after weir removal using physical habitat simulations (PHSs). The functional group approach was used in the PHSs for the macroinvertebrate community. In the functional group approach, macroinvertebrates are classified based on the traits of their food acquisition (i.e., the functional feeding group) or habitat selection (i.e., the functional habit group). In the present study, macroinvertebrate species were divided into the functional habit groups (FHGs) of swimmers, clingers, burrowers, and sprawlers. Hydraulic simulations and habitat simulations were carried out using the River2D model and habitat suitability curves (HSCs), respectively. The distributions of the composite suitability index (CSI) for the FHGs were obtained over the entire study area, and the changes in the suitability of the habitat for the target FHGs were evaluated. The simulation results indicated that habitat suitability for swimmers, clingers, and sprawlers was improved. However, habitat suitability for burrowers was degraded after the weir was removed. Consequently, the removal of the weir increased the diversity of the macroinvertebrate community, thus improving the health of the aquatic ecosystem.

Trophic state index validation based on the phytoplankton functional group approach in Amazon floodplain lakes

ABSTRACTMany trophic indices have been constructed for temperate aquatic environments, but few have proved reliable for tropical environments. Indices constructed on the basis of nutrients may not be effective for describing the trophic state because the fractions of nitrogen and phosphorus differ in their potential to predict the nutrient limitation in tropical aquatic environments. We developed an index based on the phytoplankton Reynolds functional groups for an Amazonian floodplain lake from samples collected during 2 contrasting hydrological periods (rising and flushing) and compared it with the index initially proposed by Carlson in 1977 and further adapted to tropical environments by Toledo in 1990. The functional group and Carlson indices matched only 37% and 56% of the sample units collected during the rising and flushing periods, respectively. Our study confirms the difficulty of assessing trophic states using only phosphorus and chlorophyll a in tropical floodplain lakes. In this environment (1) nitrogen may significantly limit phytoplankton growth and (2) complex phytoplankton–nutrient relationships occur during the hydrological cycle that cannot be accounted for through a simple phosphorus and chlorophyll a formula.

A functional group approach reveals important fish recruitments driven by flood pulses in floodplain ecosystem

The periodical flood pulses, assisting by the connectivity between rivers and lakes in floodplain ecosystems, are of paramount importance in underpins fish meta-communities. Regardless of the unprecedented anthropogenic disturbances on natural flood regimes, there is limited understanding for the response of fish assemblages to flood pulses. Most studies documented the issue sorely on floodplain rivers or floodplain lakes, but the dynamics of fish communities in the transitional floodplains accounting for both lentic and lotic environments are rarely reported. Here we measure temporal (high and low water seasons) and spatial (lotic and lentic environments) patterns of fish assemblages in the transitional floodplain between the Yangtze River and Lake Caizi using taxonomic and functional group metrics. Our results demonstrated significantly variations in fish community composition among different environments between high and low water seasons. During flooding season in high water phase, we observed significantly patchy population recruitments of riverine fish species. Then in low water season, widespread lake residents dominated the lentic environments due to their higher environment tolerance. Benefitting from the functional group measurement, we identified three flooding related functional groups i.e., G2, G9 and G10 (consisting of riverine catfishes, gudgeons, and loaches), that may bear the brunt of natural flood pulses alterations. Despite the significant variations of richness in taxonomic diversity, we detected higher sensitivity of functional diversity, since three functional diversity indices were significantly higher in high water season. This findings demonstrated important functional recruitments triggered by flood pulses, highlighting a pressing need to sustain natural flood regime with hydrological connectivity for better conservation of fish assemblages in floodplain ecosystem.

Assessing Benthic Responses to Fishing Disturbance Over Broad Spatial Scales That Incorporate High Environmental Variation

Marine benthic habitats are modified by a number of human- related disturbances. When these disturbances occur at large scales over areas of high environmental variability, it is difficult to assess impacts using metrics such as species richness or individual species distributions because of varying species-specific responses to environmental drivers (e.g., exposure, sediment, temperature). Impact assessment can also be problematic when assessed at broad spatial scales because of regional heterogeneity of species pools. Even when effects on individual species can be detected, it is difficult to upscale from individual species to ecosystem scale effects. Here, we use a functional group approach to assess broad scale patterns in ecological processes with respect to fishing and environmental drivers. We used data from field surveys of benthic communities from two large, widely separated areas in New Zealand’s EEZ (Chatham Rise and Challenger Plateau). We assigned 828 taxonomic units (most identified to species) into functional groups related to important ecosystem processes and likely sensitivity to, and recovery from, fishing disturbance to the seafloor. These included: opportunistic early colonists; substrate stabilisers (e.g., tube mat formers); substrate destabilisers; shell hash-creating species; emergent epifauna; burrowers; and predators and scavengers. Effects of fishing disturbance on benthic functional composition were observed, even at this broad spatial scale. Responses varied between functional groups, with some being tolerant of fishing impacts and others showing rapid declines with minimal fishing effort. The use of a functional group approach facilitates assessment of impacts across regions and species, allowing for improved generalisations of impacts to inform management and decision making.

Traditional plant functional groups explain variation in economic but not size-related traits across the tundra biome.

AimPlant functional groups are widely used in community ecology and earth system modelling to describe trait variation within and across plant communities. However, this approach rests on the assumption that functional groups explain a large proportion of trait variation among species. We test whether four commonly used plant functional groups represent variation in six ecologically important plant traits.LocationTundra biome.Time periodData collected between 1964 and 2016.Major taxa studied295 tundra vascular plant species.MethodsWe compiled a database of six plant traits (plant height, leaf area, specific leaf area, leaf dry matter content, leaf nitrogen, seed mass) for tundra species. We examined the variation in species‐level trait expression explained by four traditional functional groups (evergreen shrubs, deciduous shrubs, graminoids, forbs), and whether variation explained was dependent upon the traits included in analysis. We further compared the explanatory power and species composition of functional groups to alternative classifications generated using post hoc clustering of species‐level traits.ResultsTraditional functional groups explained significant differences in trait expression, particularly amongst traits associated with resource economics, which were consistent across sites and at the biome scale. However, functional groups explained 19% of overall trait variation and poorly represented differences in traits associated with plant size. Post hoc classification of species did not correspond well with traditional functional groups, and explained twice as much variation in species‐level trait expression.Main conclusionsTraditional functional groups only coarsely represent variation in well‐measured traits within tundra plant communities, and better explain resource economic traits than size‐related traits. We recommend caution when using functional group approaches to predict tundra vegetation change, or ecosystem functions relating to plant size, such as albedo or carbon storage. We argue that alternative classifications or direct use of specific plant traits could provide new insights for ecological prediction and modelling.

Surrogate formulation for diesel and jet fuels using the minimalist functional group (MFG) approach

Surrogate fuels aim to reproduce real fuel combustion characteristics in order to enable predictive simulations and fuel/engine design. In this work, surrogate mixtures were formulated for three diesel fuels (Coryton Euro and Coryton US-2D certification grade and Saudi pump grade) and two jet fuels (POSF 4658 and POSF 4734) using the minimalist functional group (MFG) approach, a method recently developed and tested for gasoline fuels. The diesel and jet fuel surrogates were formulated by matching five important functional groups, while minimizing the surrogate components to two species. Another molecular parameter, called as branching index (BI), which denotes the degree of branching was also used as a matching criterion. The present works aims to test the ability of the MFG surrogate methodology for high molecular weight fuels (e.g., jet and diesel). 1H Nuclear Magnetic Resonance (NMR) spectroscopy was used to analyze the composition of the groups in diesel fuels, and those in jet fuels were evaluated using the molecular data obtained from published literature. The MFG surrogates were experimentally evaluated in an ignition quality tester (IQT), wherein ignition delay times (IDT) and derived cetane number (DCN) were measured. Physical properties, namely, average molecular weight (AMW) and density, and thermochemical properties, namely, heat of combustion and H/C ratio were also compared. The results show that the MFG surrogates were able to reproduce the combustion properties of the above fuels, and we demonstrate that fewer species in surrogates can be as effective as more complex surrogates. We conclude that the MFG approach can radically simplify the surrogate formulation process, significantly reduce the cost and time associated with the development of chemical kinetic models, and facilitate surrogate testing.

Grupos funcionales fitoplanctónicos en una laguna algal de alta tasa usada para la biorremediación de lixiviados de rellenos sanitarios

The functional group (FG) approach is used to predict the response of the composition of phytoplankton species to changes in the environmental conditions. We assessed for the first time the dynamics of phytoplankton communities in a High-Rate Algal Pond (HRAP), implemented for the bioremediation of landfill leachate, and using morphology-based functional groups (MBFG), under the American tropics conditions. These groups were later correlated with the physical and chemical variables of the system. Water samples were taken for biological, physical and chemical analysis for seven months. In addition, phytoplankton biovolumes were estimated and a canonical correlation analysis was performed to explain the relation between physical and chemical variables and FGs. Subsequently, the HRAP treated a medium-age leachate characterized by high concentrations of nutrients. Four MBFGs were identified (IV, V, VI and VII). Group V, conformed by phytoflagellates, was found to be dominant during the entire study period. This group proliferate in environments with high concentrations of organic matter, while contributing to the transformation of the contaminants present in the leachate. The largest biovolumes of Groups V and VII occurred during periods of low water levels and dissolved organic carbon. Finally, we show that the MBFG technique may be useful in understanding the dynamics of the phytoplankton community in the HRAP used for the treatment of landfill leachate.

Chemical functional group descriptor for ignition propensity of large hydrocarbon liquid fuels

The chemical functional group approach is investigated to verify the fundamental applicability of low-dimensional descriptors in the prediction of global combustion behavior, as described by homogeneous reflected shock ignition delay times. Three key chemical functional groups, CH2, CH3 and benzyl-type, are used to represent n-alkyl, iso-alkyl, and aromatic functionalities, respectively. To examine whether such descriptors can appropriately reflect the influences of these functionalities on ignition delay, Quantitative Structure-Property Relationship (QSPR) regression analysis is performed with the formulation of analytical models based on a fundamental Arrhenius-type description. The models are trained using literature measurements of reflected shock ignition delay times for stoichiometric fuel/air mixtures at 20 atm. Sensitivity analyses applied to the QSPR regression models show that the CH2 functional group dominates chemical kinetic behaviors at low temperature, while the chemical kinetic impacts of CH2, CH3, and benzyl-type functional groups all diminish as temperature increases. Further analyses of constant-volume adiabatic ignition delay predictions using detailed chemical kinetic models demonstrate influences of n-alkyl, iso-alkyl, and aromatic functionalities at both low and high temperature, consistent with those found for the QSPR regression models. Finally, 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy is used to directly quantify the chemical functional group compositions of both petroleum-derived and alternative jet fuels. Combining the QSPR model with NMR spectra interpretation, the applicability of current approach as an expeditious tool to accurately characterize the ignition propensity of real transportation fuels is demonstrated by comparison with experimental measurements.

Kinetics study of the fully bio-based poly(propylene succinate) synthesis. Functional group approach

Currently, the increasing importance of the bio-based chemical compounds development is visible in the polymer chemistry, chemical engineering and materials science. It is well-known that the various purity level and different contaminants characterize petrochemical-based compounds compared to their bio-based counterparts. Therefore, it is necessary to find out the contaminants impact on the bio-based monomers synthesis. One of the most important information about the reaction pathway gave the kinetics study. In this work, the fully bio-based poly (propylene succinate)s were synthesized under various temperature conditions via two-step polycondensation reaction. The kinetics studies were investigated with the use of a functional group approach. The first step of the polycondensation reaction was autocatalytic esterification reaction. During the second step, the polycondensation catalyst was used. For macromolecular structure characteristics and the progress of the chemical reaction monitoring, Fourier Transform Infrared Spectroscopy, Proton Nuclear Magnetic Resonance, and Gel Permeation Chromatography were conducted. The activation energy value of 38.5 kJ/mol was determined for the first step of the bio-based polyols synthesis. The results of the investigations verified that the activation energy for the bio-based poly (propylene succinate) synthesis revealed lower value than the same polyester synthesis based on the petrochemical monomers. Thermal analysis by TGA measurements allowed confirmed the high thermal stability of the prepared bio-based polyols equaled ca. 418 °C.

Precrop Functional Group Identity Affects Yield of Winter Barley but Less so High Carbon Amendments in a Mesocosm Experiment.

Nitrate leaching is a pressing environmental problem in intensive agriculture. Especially after the crop harvest, leaching risk is greatest due to decomposing plant residues, and low plant nutrient uptake and evapotranspiration. The specific crop also matters: grain legumes and canola commonly result in more leftover N than the following winter crop can take up before spring. Addition of a high carbon amendment (HCA) could potentially immobilize N after harvest. We set up a 2-year mesocosm experiment to test the effects of N fertilization (40 or 160 kg N/ha), HCA addition (no HCA, wheat straw, or sawdust), and precrop plant functional group identity on winter barley yield and soil C/N ratio. Four spring precrops were sown before winter barley (white lupine, faba bean, spring canola, spring barley), which were selected based on a functional group approach (colonization by arbuscular mycorrhizal fungi [AMF] and/or N2-fixing bacteria). We also measured a subset of faba bean and spring barley for leaching over winter after harvest. As expected, N fertilization had the largest effect on winter barley yield, but precrop functional identity also significantly affected the outcome. The non-AMF precrops white lupine and canola had on average a positive effect on yield compared to the AMF precrops spring barley and faba bean under high N (23% increase). Under low N, we found only a small precrop effect. Sawdust significantly reduced the yield compared to the control or wheat straw under either N level. HCAs reduced nitrate leaching over winter, but only when faba bean was sown as a precrop. In our setup, short-term immobilization of N by HCA addition after harvest seems difficult to achieve. However, other effects such as an increase in SOM or nutrient retention could play a positive role in the long term. Contrary to the commonly found positive effect of AMF colonization, winter barley showed a greater yield when it followed a non-AMF precrop under high fertilization. This could be due to shifts of the agricultural AMF community toward parasitism.

Olive canopy arthropods under organic, integrated, and conventional management. The effect of farming practices, climate and landscape

ABSTRACTSeveral beneficial components of biodiversity are hosted in the olive tree canopy, providing significant agroecosystem services. Olive canopy arthropods were studied under different management systems and in regard to variables related to farming practices, climate, and landscape. Arthropods were monitored weekly in 24 olive orchards for 2 years using transparent sticky traps. Farm management parameters, as well as climate conditions and landscape complexity, were recorded. Canopy arthropods and main olive pests were classified and aggregated upon functionality. Comparison between management systems was performed. Multivariate analysis was conducted with farming practices, climate conditions and landscape complexity as explanatory variables. Significant differences were not found between management systems, due to high variability of farming practices applied within the same management system. Factors linked to farm management, climate, and landscape explained arthropod variability better than management systems. The functional group approach appeared to be a meaningful, complementary biodiversity measure. Findings suggest that specific farm management, environmental, and landscape factors should be taken into account in agroecological research.

A minimalist functional group (MFG) approach for surrogate fuel formulation

Surrogate fuel formulation has drawn significant interest due to its relevance towards understanding combustion properties of complex fuel mixtures. In this work, we present a novel approach for surrogate fuel formulation by matching target fuel functional groups, while minimizing the number of surrogate species. Five key functional groups; paraffinic CH3, paraffinic CH2, paraffinic CH, naphthenic CHCH2 and aromatic CCH groups in addition to structural information provided by the Branching Index (BI) were chosen as matching targets. Surrogates were developed for six FACE (Fuels for Advanced Combustion Engines) gasoline target fuels, namely FACE A, C, F, G, I and J. The five functional groups present in the fuels were qualitatively and quantitatively identified using high resolution 1H Nuclear Magnetic Resonance (NMR) spectroscopy. A further constraint was imposed in limiting the number of surrogate components to a maximum of two. This simplifies the process of surrogate formulation, facilitates surrogate testing, and significantly reduces the size and time involved in developing chemical kinetic models by reducing the number of thermochemical and kinetic parameters requiring estimation. Fewer species also reduces the computational expenses involved in simulating combustion in practical devices. The proposed surrogate formulation methodology is denoted as the Minimalist Functional Group (MFG) approach. The MFG surrogates were experimentally tested against their target fuels using Ignition Delay Times (IDT) measured in an Ignition Quality Tester (IQT), as specified by the standard ASTM D6890 methodology, and in a Rapid Compression Machine (RCM). Threshold Sooting Index (TSI) and Smoke Point (SP) measurements were also performed to determine the sooting propensities of the surrogates and target fuels. The results showed that MFG surrogates were able to reproduce the aforementioned combustion properties of the target FACE gasolines across a wide range of conditions. The present MFG approach supports existing literature demonstrating that key functional groups are responsible for the occurrence of complex combustion properties. The functional group approach offers a method of understanding the combustion properties of complex mixtures in a manner which is independent, yet complementary, to detailed chemical kinetic models. The MFG approach may be readily extended to formulate surrogates for other complex fuels.

Functional diversity of phytoplankton highlights long‐term gradual regime shift in the middle section of the Danube River due to global warming, human impacts and oligotrophication

Abstract Long‐term dynamics of phytoplankton have been addressed in marine and lake systems, but rarely in rivers. Large rivers, however, are highly human‐impacted, whereas global warming may further affect the functioning of phytoplankton at long‐term scale. In the middle section of the large European Danube River, long‐term decrease in phytoplankton biomass (Chl‐a) and increase in species diversity have formerly been revealed. The functional community composition that relates to ecosystem functioning directly has not been addressed previously. We analyse a 34‐year‐long phytoplankton data set from the middle river section at Göd (N‐Budapest), Hungary. We focus on gradual changes in the functional composition and functional diversity components based on the functional trait and functional group approaches. We hypothesised that long‐term gradual changes in major environmental constraints should be followed by gradual shifts in dominance relationships among functional traits and functional groups of phytoplankton. We further hypothesised that functional shifts were highlighted by gradual changes in functional diversity components: evenness, divergence and dispersion. Water discharge of the middle Danube shifted towards the more frequent occurrence of lower values. On the other hand, high floods (>3,000 m3/s) increased significantly with shortening tendency in duration and altered seasonality. The concentration of N and P forms, as well as total suspended solids decreased significantly. Water temperature increased significantly, especially in summer. In the phytoplankton, single‐celled eutrophic centric diatoms decreased in relative abundance, but flagellated, elongated and filamentous forms increased. A clear functional shift was the dominance decrease in planktonic taxa and the relative abundance increase in benthic diatoms. All functional diversity components increased significantly in the entire data set, except functional evenness (FEVE) based on the functional group approach. At seasonal scale, all significant trends showed increases, except the FEVE components of the functional group approach, which decreased in winter and spring significantly. Long‐term increase in functional diversity components alone could indicate enhanced ecosystem functioning of phytoplankton in the middle section of the Danube. However, we argue that the observed increase in functional diversity may be related to a gradual shift from high‐biomass communities with the dominance of eutrophic centric diatoms towards the relative increase in several, but low‐biomass elements. These include a few planktonic algae well adapted to the altered conditions, diatoms with benthic origin and dispersed limnophilic taxa. Our results provide the first evidence for a long‐term phytoplankton functional regime shift in a European large river. Global warming, human impacts and oligotrophication might potentially increase the functional diversity of large river phytoplankton, but the origin and functional role of taxa should carefully be considered. The observed functional shift in phytoplankton might also be indicative for alterations in the food‐web structure of the middle section of the Danube River at long‐term scale.

Species-based classification reveals spatial processes of phytoplankton meta-communities better than functional group approaches: a case study from three freshwater lake regions in China

Phytoplankton communities respond rapidly to environmental selection at a given locality, and they are also shaped by spatial processes at certain scales. The extracted effect of environmental selection and spatial processes may vary if different classification approaches are applied to phytoplankton and the spatial scales. In this study, summer phytoplankton of 43 lakes from three major lake regions in China were investigated and phytoplankton were classified with three approaches: taxonomy of species, habitat template-based functional groups, and morphology-based functional groups. Within a single lake region, the pattern of phytoplankton meta-community was significantly explained by environmental but not by spatial variables. In a larger scale covering all the three lake regions, both environmental and spatial variables explained the variance of the phytoplankton community, but the spatial variables were detected only by classification with species, and only the environmental variables were detected with phytoplankton functional groups. This study revealed that although vegetative populations of different species sorted into the same functional group have common response to environmental changes, their dispersal abilities, mechanisms, and strategies might differ markedly and therefore the species-specific approach cannot be disregarded when studying phytoplankton patterns at spatial scales.

Variability of ant community composition in cork oak woodlands across the Mediterranean region: implications for forest management

Abstract: We evaluated the potential use of ants as a powerful tool for environmental monitoring, together with the applicability of the functional group approach as an alternative method for studying ant communities in cork oak woodlands. Variations in ant community composition, diversity and functional groups were studied in two cork oak forested sites across the Mediterranean region. Ants were sampled using pitfall traps placed along linear transects at 12 sites located in the main cork districts of Italy and Morocco (Gallura in Sardinia, and Maâmora, east of Rabat). A total of 13.501 specimens were collected, belonging to 38 species (five shared species). A distinct separation in the NMDS plots between Gallura and Maâmora ant assemblages was clearly visible. Ant species composition was widely different between the two districts and significant differences were detected within the Gallura district at the species level. Opportunist species were well represented in Gallura (about 27% of average Bray-Curtis similarity) as well as cryptic species (over 23%). In the Maâmora forest, generalized Myrmicinae, hot climate specialists and opportunists contributed equally to the average similarity (together about 53%). Multi-scale ant diversity showed that the true turnover was higher in Gallura than in Maâmora. These findings support the idea that the functional group approach, rather than species diversity per se, could be considered as a valuable tool to detect the response of the ant community to environmental changes in Mediterranean cork oak woodlands. Using ants as bioindicators could help not only in detecting early warning signs of habitat disturbance, but also in defining a useful management strategy to increase the resilience of agroforestry systems under future global change scenarios.

Limited effects of low-intensity forest management on ant assemblages in southwestern Amazonian forests

One important strategy to conciliate forest conservation and economic development is the use of reduced-impact logging techniques. Here we evaluated the effects of low-intensity forest management on ant assemblages and vegetation structure in a managed area in the southeast of Acre State, Brazil. Ground-dwelling and arboreal ants, and several forest-structure descriptors were sampled in nine paired areas located in control (unlogged) and logged areas in 2005, 2007 and 2009. None of the forest structure predictors were related with either the treatment or the time since logging. However, some ant assemblage’ descriptors were related with logging activities. Arboreal and ground-dwelling ant species richness was similar between unlogged and logged areas, but more ground-dwelling ant species were found in areas logged in 2005 compared with areas logged in 2009. Ground-dwelling ant assemblage composition differed between treatments (logged and unlogged) and year of logging, but species composition heterogeneity was similar between areas. Arboreal ant assemblage composition was not related with treatment and year of logging, but assemblage composition was more heterogeneous in managed areas, suggesting that species that forage on the understory vegetation may be more resilient than ground-dwelling species. The general results of functional group approach suggest that changes of species composition between control and managed areas are more related with differences in ant species occurrence than ant species richness. Selective logging had limited effect on both vegetation descriptors and ant assemblage structure, suggesting that the conciliation of impact reduction techniques with low intensity extraction seems a promising alternative for sustainable logging activity in tropical forests.

Reconstruction of chemical structure of real fuel by surrogate formulation based upon combustion property targets

The global chemical character of complex chemical fuel mixtures is explicitly determined by evaluating the abundances of chemical functional groups present within them rather than by applying a traditional interpretation based upon molecular species composition. Statistical analyses of the relationships among each chemical functional group and specific combustion property targets (CPTs) of the fuel are rigorously developed. The results demonstrate that the four CPTs currently used in aviation kerosene surrogate formulation - H/C molar ratio, derived cetane number (DCN), average molecular weight (MW), and threshold sooting index (TSI) - effectively constrain the chemical functional group distribution of the fuel, and, hence, the global combustion behaviors of pre-vaporized fuel/air mixtures. Successful emulation of the CPTs for a target real fuel involves developing a surrogate mixture that defines an “equivalent” chemical functional group distribution to that of the target fuel. Among the CPTs used for real fuel surrogate development, DCN does not abide by a linear blending rule, which generally frustrates development of surrogates. However, a quantitative structure–property relation (QSPR) regression for DCN is demonstrated here using the chemical functional group approach. Results of the regression reveal that the (CH2)n group plays the most significant role in determining the fuel autoignition propensity, followed by the influences of CH3 and benzyl-type groups. The QSPR functional group approach extends to provide a powerful tool to address potential preferential vaporization effects dictated by fuel distillation characteristics. Further analysis of fuel chemical property variation (DCN and H/C ratio) over the distillation curve (and other physical properties) provides a foundation for understanding the complex combustion behaviors of multi-phase and multi-component fuels relevant to real gas turbine engine applications.

Temporal dynamics of phytoplankton using the morphology-based functional approach in a subtropical river

Phytoplankton functional classification based on simple morphological traits may simplify our understanding of variation in this community as a function of environmental filters. We tested the effectiveness of the morphology-based functional group (MBFG) approach as a model of phytoplankton temporal dynamics in a Brazilian subtropical river. The Sao Joao River has an area of approximately 79.10 km2, with 28.09 km2 located within the Iguacu National Park, in Foz do Iguacu, Parana, Brazil. We collected phytoplankton samples and measured environmental variables in the intermediate river section on a monthly basis between August 2008 and July 2009. We tested for differences between the environmental variables, phytoplankton biovolume and sampled months and identified the environmental variables with the greatest influence on MBFGs. Our results revealed clear temporal variability of environmental conditions in this river. We recorded the presence of seven MBFGs (I, II, III, IV, V, VI and VII) in the lotic environment, with MBFG IV (chlorococcal chlorophyceans and desmids), V (flagellates) and VI (diatoms) being the most frequent and most important groups for phytoplankton biomass. Significant temporal differences were found for MBFGs I, II, IV, V and VI, with a clear seasonal succession, especially among MBFGs V and VI. Temperature, pH, electrical conductivity, transparency and nutrients were the main predictors of MBFGs in the Sao Joao River. Approaches based on traits have been increasingly applied in community ecology, and we believe that the MBFG approach can increase our understanding of environmental dynamics as well as improve the assessment of general ecological issues.

Optimum Batch-Reactor Operation for the Synthesis of Biomass-Derived Renewable Polyesters

For the first time, we present the process simulation and multiobjective optimization of the batch-reactor polyesterification of a library of biomass-derived renewable polyesters: poly(1,5-pentylene 2,5-furandicarboxylate) (PTF), poly(1,5-pentylene succinate) (PTS), and poly(1,5-pentylene 2,5-furandicarboxylate-co-1,5-pentylene succinate (PTFTS). The simulation environment was implemented in Aspen Plus, and the e-constraint method was employed for the optimization problem, considering two objective functions that maximize the number-average degree of polymerization (DPN) and minimize the heat duty Q. The performance of the biobased polyesters was compared to that of poly(ethylene terephthalate) (PET). The kinetic rate expressions were defined following the functional-group approach, and the parameters were estimated by fitting a polyesterification model found in the literature to the experimental data. The present work provides comprehensive fundamental information toward a feasible process design and sca...

Trait based and functional group approaches in algal ecology

Trait based and functional group approaches in algal ecology