Biomass Size Research Articles

Relationships Between Plankton Size Spectra, Net Primary Production, and the Biological Carbon Pump

AbstractPhotosynthesis in the surface ocean and subsequent export of a fraction of this fixed carbon leads to carbon dioxide sequestration in the deep ocean. Ecological relationships among plankton functional groups and theoretical relationships between particle size and sinking rate suggest that carbon export from the euphotic zone is more efficient when communities are dominated by large organisms. However, this hypothesis has never been tested against measured size spectra spanning the >5 orders of magnitude found in plankton communities. Using data from five ocean regions (California Current Ecosystem, North Pacific subtropical gyre, Costa Rica Dome, Gulf of Mexico, and Southern Ocean subtropical front), we quantified carbon‐based plankton size spectra from heterotrophic bacteria to metazoan zooplankton (size class cutoffs varied slightly between regions) and their relationship to net primary production and sinking particle flux. Slopes of the normalized biomass size spectra (NBSS) varied from −1.6 to −1.2 (median slope of −1.4 equates to large 1–10 mm organisms having a biomass equal to only 7.6% of the biomass in small 1–10 μm organisms). Net primary production was positively correlated with the NBSS slope, with a particularly strong relationship in the microbial portion of the size spectra. While organic carbon export co‐varied with NBSS slope, we found only weak evidence that export efficiency is related to plankton community size spectra. Multi‐variate statistical analysis suggested that properties of the NBSS added no explanatory power over chlorophyll, primary production, and temperature. Rather, the results suggest that both plankton size spectra and carbon export increase with increasing system productivity.

Features of the Mechanism of Gas-phase Ignition of Wood Biomass Particles

ABSTRACT Use of woody biomass instead of coal as fuel for thermal power plants (TPP) is considered a promising direction for reducing emissions of anthropogenic substances during the operation of coal-fired thermal power plants. But the process of replacing coal with wood in the thermal power industry is happening very slowly due to objective reasons. The main one is the deposition of particles that have not fully passed the pyrolysis stage (in this case, a layer of substance in a resinous state is retained in the wood particle) on heating surfaces (for example, superheaters) and a decrease in the efficiency of using the heat of combustion of fuel as a result of contamination of the heating surfaces. Therefore, when developing technologies for burning dispersed wood in the furnaces of boiler units, reliable experimental data are required on the characteristic times of ignition and combustion of woody biomass particles, taking into account the time of transition from local (focal) gas-phase ignition to the combustion of volatiles in the entire vicinity of the particle (tsf). The article presents the results of experimental studies of flame propagation processes in the small vicinity of a particle during the ignition period. The experiments made it possible to establish that the flame propagation velocity in the small vicinity of the particle significantly depends on the ambient temperature. It is shown that under conditions of low-temperature heating (air temperature Tg = 873 K), the propagation velocity of the combustion (flame) is minimal. An increase in Tg values (from 873 K to 1273 K) leads to a significant (4–5 times) increase in the time of complete flame coverage of the particle. According to the results of the experiments, two heating modes were identified: high-temperature and low-temperature with a conditional interface Tg = 873 K. At Tg = 873 K, the characteristic particle size of wood biomass has no significant effect on the characteristics and conditions of flame propagation in a small vicinity of the particle. An increase in the ambient temperature (up to 1273 K) leads to an increase in the influence of particle size on the characteristics and conditions of flame propagation. A hypothesis describing the process of flame propagation has been developed.

Biomass difference between mixed plantations and monocultures and its influencing factors: A meta‐analysis

AbstractEstablishing mixed‐species plantations has become the most promising planting method to provide various goods and improve multiple environmental services. Although mixed planting has the potential to increase tree biomass, the divergent findings make it challenging to understand the mixing effects on whole forest (trees, shrubs, herbs, and litter) biomass. Therefore, we conducted a meta‐analysis compiling 156 studies published from 1982 to 2021 across 128 sites in China. We aimed to quantify the mixing effects on forest biomass between mixed plantations and monocultures and disentangle the driving factors. Our results showed that mixed planting significantly increased the total biomass, biomass of tree, and shrub layer by 14.07%, 22.49%, and 34.84%, respectively, when compared with monocultures. The effects of mixed planting on biomass were more pronounced in plantations with both nitrogen‐fixing trees and non‐nitrogen‐fixing trees, plantations with both coniferous and broad‐leaved trees, as well as uneven‐aged plantations containing young‐ and middle‐aged species. Furthermore, our results demonstrated the effects of mixed planting were predominantly governed by climatic conditions and woodland characteristics. The effect size of total biomass exhibited a significant positive correlation with mean annual temperature and precipitation, while the shrub and herb layers showed a significant negative relationship with these climatic variables. Our findings highlighted the importance of complementarity effects in mixed plantations, especially establishing uneven‐aged plantations with different leaf morphology types and N acquisition strategies. Overall, our meta‐analysis could provide strategies for future sustainable ecosystem management and improving the terrestrial carbon sink.

Parametric evaluation of clean syngas production from pine forest residue by chemical looping gasification at the 20 kWth scale

In the framework of the EU H2020 CLARA project, jet biofuel production via Fischer-Tropsch synthesis is intended from syngas generated by Biomass Chemical Looping Gasification (BCLG). BCLG is based on the lattice oxygen transference between a solid oxygen carrier and the biofuel to energetically support the biomass gasification. This process produces low tar and nitrogen-free syngas under autothermal conditions, and at the same time includes an intrinsic separation of carbon compounds from nitrogen in air, avoiding future carbon capture costs. This work evaluates the syngas production from pine forest residue (PFR) through the BCLG process with ilmenite as the oxygen carrier. The effects of several key operating variables, including temperature, oxygen-to-biomass ratio and mean residence time of solids, on the performance of the BCLG process were analyzed at 20 kWth scale. The syngas yield depended on the oxygen-to-biomass ratio and improved with the char conversion in the fuel reactor. Temperature and mean residence time of solids in the fuel reactor were identified as the primary factors affecting char conversion. A dedicated study was performed to assess the impact of the biomass size on char conversion, as well as the relevance of a carbon stripper unit on the improvement on char gasification due to its role either as a secondary gasifier or as a char-oxygen carrier separator. Higher char conversion values were achieved with the lowest biomass particle size (1–2 mm vs. pellets 6 mm Ø) due to lower restrictions to gas diffusion inside the particles. The carbon stripper may act as a secondary gasifier, thus improving the char conversion, but it was not able to take away the unconverted char particles from ilmenite in any case due to it was designed for powdered fuels. Besides, the generation of light hydrocarbons was hardly affected by any operating variables. The tar content remained below 4.5 g/kg dry biomass. The ilmenite showed a good performance during the continuous operation without signs of defluidization.

Predicting hydrogen production from co-gasification of biomass and plastics using tree based machine learning algorithms

Hydrogen production from co-gasification of biomass and plastics are predicted using Machine Learning Algorithms, e.g., Decision tree and Ensemble methods. Independent variables are particle sizes of biomass and plastics, feedstock ratio and temperatures. The dependent variable is Hydrogen production. Model and prediction performances were evaluated/validated using model parameters. The relative importance scores for independent variables are RSS particle size > HDPE particle size > Temperature > Percent plastics. Size dependence of Hydrogen production indicated a surface-controlled reaction. Temperatures between 500 °C and 900 °C have less impact on H2 production compared to the size. Predictions were carried out using Train-test split, Cross-validation, and GridsearchCV model on the data unseen. Gradient Boosting performed the best.

Numerical investigation of mixing and heat transfer of mixed biomass and silica sand particles in a bubbling fluidized bed combustor

Using fluidized bed combustion technology, biomass is being promoted for electricity production. However, a lack of biomass in a particular location or season poses a problem, leading to low thermal efficiency when using a single biomass. Thus, mixed biomass is considered a potential solution. This study uses CFD-DEM simulation to investigate the effects of various biomass types, loadings, and blending ratios on hydrodynamics and heat transfer in a bubbling fluidized bed. Coarse bagasse size provides the most efficient mixing behavior for a single biomass mixture. A blending ratio of 1:3 wood chip to coarse bagasse with 5% biomass loading, using 1 mm silica sand, is the appropriate condition. The primary factor for mixing is the difference in biomass sizes, while different biomass loadings have no significant influence. Smaller sand particles enhance the mixing and heat transfer. These findings provide useful guidelines for efficient biomass conditions in fluidized bed combustors.

The nutritional composition and cell size of microbial biomass for food applications are defined by the growth conditions

BackgroundIt is increasingly recognized that conventional food production systems are not able to meet the globally increasing protein needs, resulting in overexploitation and depletion of resources, and environmental degradation. In this context, microbial biomass has emerged as a promising sustainable protein alternative. Nevertheless, often no consideration is given on the fact that the cultivation conditions affect the composition of microbial cells, and hence their quality and nutritional value. Apart from the properties and nutritional quality of the produced microbial food (ingredient), this can also impact its sustainability. To qualitatively assess these aspects, here, we investigated the link between substrate availability, growth rate, cell composition and size of Cupriavidus necator and Komagataella phaffii.ResultsBiomass with decreased nucleic acid and increased protein content was produced at low growth rates. Conversely, high rates resulted in larger cells, which could enable more efficient biomass harvesting. The proteome allocation varied across the different growth rates, with more ribosomal proteins at higher rates, which could potentially affect the techno-functional properties of the biomass. Considering the distinct amino acid profiles established for the different cellular components, variations in their abundance impacts the product quality leading to higher cysteine and phenylalanine content at low growth rates. Therefore, we hint that costly external amino acid supplementations that are often required to meet the nutritional needs could be avoided by carefully applying conditions that enable targeted growth rates.ConclusionIn summary, we demonstrate tradeoffs between nutritional quality and production rate, and we discuss the microbial biomass properties that vary according to the growth conditions.

Long-term oscillations in the normalized biomass-size spectrum reveal the impact of oligotrophication on zooplankton trophic structure in the North Atlantic Subtropical Gyre

Ocean warming of the North Atlantic Subtropical Gyre (NASG) induced oligotrophication and a decrease in integrated net primary production during the 2010s, potentially affecting higher trophic levels. We analyzed long-term records (1994–2019) of daytime and nighttime zooplankton biomass in five size classes from the NASG. Daytime biomass decreased in the three largest size classes during the 2010s, while decrease in nighttime biomass was less evident due to the relative stability in diel vertical migrator biomass. We used the normalized biomass size spectrum (NBSS) to estimate the relative transfer efficiency between trophic levels. The steepness of the NBSS slope at the end of the time series increased by 14% (daytime) and 24% (nighttime) from the maximum observed annual average values (2011 and 2009, respectively). This suggests oligotrophication during the 2010s led to a significant reduction in the transfer of biomass across trophic levels, with negative impacts on the NASG planktonic food web.

Achromobacter sp. Strain BUKˍBCHˍTQ1: A Potential Paraquat-Degrading Bacterium Isolated from Pesticide Contaminated Agricultural Soil

Paraquat (1, 1′-dimethyl-4, 4′-bipyridinium dichloride) is one of the most frequently used herbicide in agriculture. It is a cationic non-systematic, non-selective contact compound that instantaneously interferes with the photosynthetic processes of plants. It has an immediate effect, once the compound comes into contact with the plants’ leaves, where the reaction occurs. However, the contamination of paraquat residue in soil can harm soil microbes, flora and fauna, farmer health and also soil ecology, which affects the soil fertility. The objective of this study was to isolate and characterize bacteria with the ability to break down and utilize paraquat as the primary carbon source. The isolation process involved the enrichment of mineral salt media (MSM) using serial dilution. The isolated bacterium underwent morphological, biochemical, and molecular identification following characterization. Results showed the isolate was identified as Achromobacter sp. with the accession number OQ372943 based on partial 16S rRNA gene sequence and phylogenetic analysis. The growth and degradation of paraquat by this isolate were optimum at a pH of 6.5, 276 mgL-1 of the substrate (paraquat), temperature of 35 °C, 200 µL of biomass size, and 48 h of incubation. The degradation efficiency of the isolate after 120 hours of incubation under optimal conditions was 91.01%. Hence, these results demonstrated a very high efficiency of paraquat degradation. Consequently, this isolate holds significant promise for paraquat degradation and could serve as a viable contender for remediating paraquat-contaminated environments.

Vertical changes in zooplankton abundance, biomass, and community structure at seven stations down to 3000 m in neighboring waters of Japan during the summer: Insights from ZooScan imaging analysis

The imaging device ZooScan is used to examine net-collected zooplankton samples. ZooScan has been applied to regional and seasonal changes in the zooplankton community, but it has rarely been used to characterize vertical changes, especially down to the deep sea. In this study, we report a ZooScan analysis of vertically stratified zooplankton samples collected by collected by Vertical Multiple Plankton Sampler down to 3000 m at seven stations near Japan in the Okhotsk Sea, Japan Sea, East China Sea, and subarctic, transitional, and subtropical North Pacific. Throughout the region, both abundance and biomass, as indicated by aggregate zooplankton volume decreased with increasing depths. ANCOVA analysis revealed that factors linked to vertical changes varied with location. Depth and region were the primary determinants of abundance and biomass, respectively. Cluster analysis based on abundance delineated 8 distinct zooplankton community groups. The occurrence of each group varied regionally and 3–5 groups were vertically stratified at each station. Across all stations, Normalized Biomass Size Spectra (NBSS) and size diversity showed pronounced change around 150–500 m depths. At shallower depths, the NBSS slope was steep, the intercept was high, and size diversity was low while, at deeper depths the opposite was true for each of those parameters. Generalized additive models showed that depth, temperature, and salinity had a significant effect on NBSS and size diversity. This study indicates that the ZooScan imaging approach may be useful in the analysis of deep-sea zooplankton communities.

The Effect of Different Waste Material Binders in Relation to Khaya Senegalensis Solid Fuel Pellet Quality

Fuel pellets are an attractive renewable energy source derived from biomass sources thanks to their uniformity and ease of handling. However, raw biomass and waste material binders have several drawbacks, which include poor physical properties, particularly low density and compositional heterogeneity, which restrict their wider use as a general source of energy. Besides, due to the low energy density, low bulk density, and uneven shape and size of raw biomass, it is very difficult to store and transport biomass in its original form, which decreases transport efficiency. This study investigated the effect of waste material binders (rice husk, corn cob, and sugarcane bagasse) on the mechanical and thermal properties of Khaya Senagalensis pellets. The mechanical and thermal properties were determined according to ASTM standards. Waste material binders have affected pellet quality such as density, bulk density, moisture content, durability, compressive strength, shatter index, water resistance, ash content, volatile matter, fixed carbon, and calorific value. From the analysis, sugarcane bagasse as a binder shows the highest quality pellet in terms of mechanical properties. Sugarcane bagasse produces the highest density (0.967g/cm3), bulk density (0.4094), durability (99.71%), shatter index (98.85%), water resistance (98.35%), and thermal properties, which are the highest volatile matter (94.71%) and the lowest ash content (1.71%). In a nutshell, sugarcane bagasse is a good binder that gives a positive impact to the K.senegalensis pellets in terms of storage and transportation compared to corn cob and rice husk binder.

Bioethanol production from alkali-pretreated rice straw: effects on fermentation yield, structural characterization, and ethanol analysis.

Current ethanol production technology has a dire need for efficient conversion of lignocellulosic biomass to fermentable sugars. The conversion requires pretreatment of the biomass, one of the most expensive steps, and thus it is quite necessary to identify the most cost-effective and high-efficiency conversion method. In this study, rice straw (RS) biomass was pretreated using 4% NaOH alkali, soaked for 4 h, and autoclaved for 30min. The structural and morphological changes were examined using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analysis in both native and alkali-treated RS. The FTIR analysis revealed that native RS contains a considerable amount of lignin that was removed after the pretreatment process. The XRD pattern of the RS revealed an increasing crystallite size of the pretreated lignocellulosic biomass. The study of SEM clearly showed the distorted structure and surface porosity after the pretreatment process. Enzymatic hydrolysis efficiency was checked by comparing the commercial enzymes and microbial hydrolysis extracted from a fungal isolate. The best-reducing sugar yield obtained was 0.62g/L, achieved at optimized conditions from the commercial enzymes. Fermentation efficiency was checked using the yeast isolate Saccharomyces cerevisiae in both the native and pretreated substrate, and the highest ethanol concentration (21.45%) was achieved using 20% w/v biomass loading, enzyme loading (2:1:1), and fermentation for a week at 30°C and pH 4.5. This concentration was higher than that of the untreated RS (3.67%). The ethanol thus produced was further checked for analysis by the 1H and 13C nuclear magnetic resonance (NMR) methods.

Zooplankton size-structure dynamics of a lowland tropical floodplain lake

Floodplains are highly complex ecosystems representing high biodiversity and conservation values, but they are also one of the world’s most threatened ecosystems due to extensive development and anthropogenic activities. Lake Tempe is a lowland riverine floodplain lake in Sulawesi Island, Indonesia, that is subject to multiple stressors such as flow alteration, eutrophication and invasive species. In this study, the dynamics of the zooplankton community size structure was investigated in Lake Tempe. Five size-based metrics, including zooplankton mean body size, total abundance, total, biomass, and normalised biomass size spectra (NBSS) slope and intercept were assessed from net-sampled zooplankton collected monthly from March to December 2016, and the role of environmental variables in shaping these size-based metrics were also examined. Zooplankton community size structure is a useful metric as it is less labour intensive than traditional approaches, provides more data accuracy and does not require highly specialised taxonomic expertise. The zooplankton community in Lake Tempe was characterised by high density of small-sized zooplankton with an average mean body size < 500 µm equivalent spherical diameter. While the zooplankton density was characterised by the dominance of the size class 300–700 µm, there was evidence of a significant contribution of the size > 700 µm towards total biomass. Seasonal hydrological regimes, water temperature and eutrophication parameters, as indicated by total phosphorus and chlorophyll-a concentration, had a significant role in driving the variability of zooplankton community size structure in this system. The results of this study are not only a significant step in providing critical baseline information on the zooplankton assemblage of Lake Tempe, but is also a significant contribution to the overall understanding of zooplankton community structure in tropical lakes, and will aid in improving lake management plans in these regions.

The effect of experimental warming on fine root functional traits of woody plants: Data synthesis

Fine root traits are critical to plant nutrition and water uptake, and soil nutrient cycling. The impacts of climate warming on woody plants are predicted to be severe, but the effects on the fine root traits of woody plants remain unclear. To evaluate the effects of warming on fine-root traits of woody plants, we synthesized 431 paired observations of 13 traits from 78 studies. The result showed that warming increased the fine root nitrogen (N) concentration, root mortality, and root respiration, but decreased fine root phosphorus (P) concentration, root C:N and root nonstructural carbohydrates (NSC) concentration. However, warming had no significant effect on fine root biomass, root production and morphological traits. Warming effects on fine root biomass and root diameter decreased with warming magnitude, while root P concentration increased. Moreover, with increasing warming duration, the effect size of specific root length (SRL), root length, root C:N and root NSC increased. The effects size of root biomass, root diameter, root length and root C:N decreased with mean annual temperature (MAT) and mean annual precipitation (MAP) increase. However, the effect size of root N concentration increased with higher MAT and MAP. Furthermore, warming increased the fine root biomass of ectomycorrhiza (ECM) plants, but decreased that of plants associated with arbuscular mycorrhizal (AM) fungi. These results indicate that the effect of warming on fine root traits of woody plants was not only modulated by warming duration and magnitude, but also MAT and MAP. Our findings highlight the differential warming responses to fine root traits of woody plants, which have strong implications for shrubs and tree-dominated ecosystems soil nutrients cycling and carbon stocks.

Simultaneous production of biogas and volatile fatty acids through anaerobic digestion using cereal straw as substrate

Cereal straw is one of the most abundant wastes worldwide, with 30.000 million tons produced per year. Bioconversion of this residual material into carboxylates by anaerobic digestion could potentially replace conventional production based on fossil feedstocks (oil). In this work, fundamental issues of this bioconversion have been explored, including: different kinds of straw (wheat, barley and rye), biomass size reduction, mass balances and modeling of the different steps of the digestion. Under optimum conditions, 44% of the raw material was effectively converted into VFAs (mainly acetate) when barley was used as substrate. Wheat and rye straw presented lower conversion rates due to the higher lignin content compared to barley straw. According to the modeling proposed, methanogenesis and hydrolysis presented very similar reaction rates, which resulted in a simultaneous production of VFAs and biogas. In view of these results, a process integration is proposed where biogas covers the thermal needs of the biotransformation of barley biomass into VFAs.

Binary mixtures of biomass and inert components in fluidized beds: Experimental and neural network exploration

In light of the little understanding of the hydrodynamics of multicomponent particle beds involving biomass, a detailed investigation has been performed, which combines well-known experimental and theoretical approaches, relying, respectively, on conventional pressure drop methods and artificial neural network (ANN) techniques. Specific research tasks related to this research includes: i. to experimentally investigate by means of visual observation the mixing and segregation behavior of selected binary mixtures by varying the biomass size and shape as well as the properties (size and density) of the granular solids in cold flow experiments; ii. to carry out a systematic experimental investigation on the effect of the biomass weight and volume fractions on the characteristic velocities (i.e., complete fluidization velocities and minimum slugging velocity) of the investigated binary mixtures in order to select the critical weight fraction of biomass in the mixtures beyond which the fluidization properties deteriorate (e.g., channelling, segregation, slugging); iii. to analyze the results obtained in about 80 cold flow experiments by means of ANN techniques in order to scrutinize the key factors that influence the behavior and the characteristic properties of binary mixtures. Experimental results suggest that the bed components’ density difference prevails over the size difference in determining the mixing/segregation behavior of binary fluidized bed, whereas the velocities of minimum and complete fluidization increased with the increase of the biomass weight fraction in the bed. The training of ANNs demonstrated good performances for both outputs (Umf and Ucf), in particular, best predictions have been obtained for Umf with a MAPE < 4% (R2 = 0.98), while for Ucf the best ANN returned a MAPE of about 7% (R2 = 0.93). The analysis on the importance of single input on ANN predictions confirms the importance of particle density of the bed components. However, unexpected results showed that morphological features of biomass have a limited importance on Ucf.

Particle size impact on pyrolysis of multi-biomass: a solid-state reaction modeling study

ABSTRACT Pyrolysis has gained significant attention due to its generation of value-added products from waste feeds in an environmentally friendly manner. The primary purpose of this study is to understand the effect of different particle sizes of biomass wastes – date stones (DS), cow manure (CM), and spent coffee grounds (SCG) – to understand better and design a biomass pyrolysis system. Thermogravimetric analysis of four different sizes of DS, SCG, and CM (range 1 mm to 125 μm) and a mixed sample (for each feed) was conducted at a heating rate of 10K/min from room temperature to 1173.15 K at inert conditions and employed model-based Coats–Redfern equations to understand the kinetic and thermodynamic parameters of the pyrolysis process. All the particle sizes except 355–125 μm for DS and SCG have the best-fit reaction mechanism of Ginstling-Brounshtein (D4). Both activation energy and pre-exponential factor decreased from 18.78 to 5.57 kJ/mol and 1.16 E+10 to 1.48 E+08 with reducing particle sizes. The onset degradation temperature, activation energy, change in enthalpy, and entropy decrease with particle sizes. The product formation is favored for all feeds and particle sizes, as the difference between the enthalpy and activation energies (Ea) is below 10 kJ/mol. As a result of their substantially lower activation energies and better reaction thermodynamics, mixed and smaller particle-sized biomass are favored.

Biological invasions and eutrophication reshape the spatial patterns of stream fish size spectra in France

AbstractAimThe global patterns of body size distributions are affected by global environmental changes (GEC), but our knowledge of the interaction effects between GEC and natural drivers is still limited. In this study, we aimed to test the effects of these interactions on fish community size spectra, that is, the variation in a community property across the body size range of individuals in the community.LocationOne thousand and ninety‐five stream locations across France between 2015 and 2018.MethodsWe fitted size spectrum slopes for each fish community based on individual biomass size and using binning and maximum‐likelihood methods through regression models across size classes and negative log‐likelihood functions, respectively. Interactions between natural drivers and GEC were tested using model‐averaging and the best models were selected with information criterion.ResultsOur results demonstrated that size spectra were steeper (i.e. higher proportion of small‐bodied individuals) in warmer than colder locations, as expected by temperature‐size rules. However, eutrophication (total phosphorus concentration) and biological invasions (percentage of non‐native individuals) modulated the effect of temperature, with flatter size spectrum slopes in streams with more nutrients and higher proportion of non‐native individuals. In addition, fish size spectrum slopes were generally steeper in upstream than in downstream locations, and this effect was more pronounced in stream locations with more nutrients. Finally, size spectrum slopes were flatter in species‐rich communities when nutrient concentration was high.Main ConclusionsOur study highlights that accounting for GEC, such as eutrophication and biological invasions, can help understanding the complex patterns of fish body size distributions in ecological communities.

Zooplankton Biomass in Ponds - Determination of Biovolume and Dry Weight

The aim of this study was to evaluate the possibility of using simple screening methods to determine zooplankton biomass in ponds. Among the applicable methods, we selected sedimentation determination of wet biomass and dry biomass determination. Of the 369 samples analysed, the median volumetric zooplankton biomass was 0.012 ml.l-1 and the median dry weight of the samples was 0.44 mg.l-1. There was a relatively close relationship between the volumetric biomass determination and the zooplankton dry weight determination, allowing only one of these methods to be used. Due to the variation of results over a wide range of values, it is more appropriate to use a logarithmic expression for the correlation. No statistically conclusive relationship was found between the zooplankton biomass determined and any of the other physico-chemical or production parameters. Nevertheless, it was possible to trace the influence of fish production, altitude and nutrient content (nitrogen and phosphorus) on the size of zooplankton biomass. The use of screening determination methods can be recommended especially for long-term monitoring of sites to get a quick overview of zooplankton biomass in ponds. It is clear from the above data that predicting the development of the zooplankton community in ponds is highly problematic. Standard determination of zooplankton biomass at regular intervals during the growing season is usually not realistic outside scientific studies due to its technical and time-consuming nature. Therefore, for long-term monitoring of the zooplankton community at a given site, it is advisable to use relatively quick and inexpensive methods of determining zooplankton biomass, such as bulk biomass or dry weight. Although these methods do not give a detailed picture of the species structure of zooplankton, they do give information on the size of the total zooplankton biomass. Together with the determination of basic physico-chemical parameters and especially chlorophyll-a, a fairly good inference can then be made on the development of plankton communities.

SUPPLEMENTS TO THE PROBLEM OF ENERGY CONSUMPTION IN REDUCING LIGNOCELLULOSES BIOMASS SIZE TO PRODUCE ENERGY

This article presents complementary results on experimental data on the process of reducing the size of plant biomass by mechanical cutting. According to the source of the experimental data, the problem of statistical modelling of the main parameters describing the process of biomass reduction was approached. A more comprehensive formulation of the list of main system parameters was also attempted, which should be considered in a minimal mathematical model. The results of this article are starting points for a systemic approach to this biomass processing process. A first systematization is fixing 13 parameters that are included in the model of the biomass size reduction phenomenon. The 13 model parameters are divided into three categories: input parameters (5), adjustment parameters (4) and output parameters (4). The performances of the interpolation formulas are evaluated using the global error and the maximum error, varying between 1% and 0.1% for the prior and 3.8% and 0.34% for the latter. Some mathematical models suggest the existence of optimal operating points. Their exploitation can only come as a result of new high-resolution experimental research, at least in terms of rotation speed.