Biomass Spectra Research Articles

Assessment of the Effect of Al2O3 and TiO2 Nanoparticles on Orange Peel Biomass and its Application for Cd (II) and Ni (II) Uptake

Abstract. In recent years, nanotechnology has been used to synthesize novel materials with several applications, such as wastewater treatment, medicine, and packaging. In this study, titanium dioxide (TiO2) and alumina (Al2O3) nanoparticles were synthesized and used to modify orange peel (OP) biomass. The resulting materials (OP-TiO2 and OP-Al2O3) were applied as biosorbents for removing nickel and cadmium from an aqueous solution. FT-IR, SEM-EDS, and XRD analyses were carried out to determine functional groups of biomass, morphology and elemental composition of the biosorbent, and average particle size, respectively. The presence of hydroxyl, carboxyl, and amine groups in the biomass spectra contributed to the adsorption process. Successful synthesis of the biosorbents due to the presence of aluminum and titanium elements was confirmed by energy dispersive x-ray spectroscopy (EDS). The average particle size was calculated as 19.13 ±4.1 nm and 58.56 ±12.64 nm for TiO2 and Al2O3, respectively. The solution pH significantly affected the adsorption process, and pH of 4 to 6 was selected as a suitable range. The highest removal yields of 87.85% and 95.6% were achieved using OP-Al2O3 for nickel and cadmium uptake, respectively. These results revealed an improvement in adsorption properties after loading the orange peel biomass with nanoparticles. Keywords: Biosorbent, Heavy metals, Nanomaterials, Wastewater treatment.

The universality of lignocellulosic biomass liquefaction by plasma electrolysis under acidic conditions

In this research, we compared the discharge characteristics and catalytic efficiency of sulfuric acid, p-toluenesulfonic acid, and their respective sodium salts (sodium sulfate and sodium p-toluenesulfonate) in sawdust liquefaction and found that sulfuric acid was the optimal catalyst when glycerol was used as solvent during the plasma electrolytic liquefaction (PEL) process. When sodium p-toluenesulfonate was used as the only catalyst, the liquefaction yield reached 83.51% after 25 min. This yield was higher than that obtained using sodium sulfate as the catalyst (60.63%) because different concentrations of H ions were produced in PEL. Cellulose, lignin, and holocellulose were extracted from sawdust and successfully liquefied in PEL, illustrating the universality of PEL. The optical emission spectra of the different biomass during the PEL process were similar, indicating that the kinds of free radicals produced were similar, which can accelerate the liquefaction of sawdust.

Isolate new microalgal strain for biodiesel production and using ftir spectroscopy for assessment of pollutant removal from palm oil mill effluent (pome)

In tropical countries, the palm oil industry discharges a large amount of wastewater. The wastewater can serve as an economical nutrient source or substrate that can support the cultivation of microalgae. This study aimed to identify the local species of microalgae potentially existing in the industrial wastewater of palm oil mill effluent (POME). POME was selected as the key source of waste due to its higher potential in producing lipids from microalgae as biofuel substrate. A novel green microalgal strain was isolated from POME of Kahang- Johor west palm oil mill in Malaysia and was identified as Chlamydomonas sp. and subsequently named UTM 98 with Catalogue No. of KR349061. This study emphasised the effectiveness of POME as the main carbon source to maintain the growth of microalgae and simultaneously to increase the lipid content. In this study, Fourier Transform Infrared spectroscopy (FTIR) and Gas Chromatography (GC-FID) were used to identify andquantify lipids in the freshwater microalgae. Cultivation of microalgae were initially carried out in 250 mL Erlenmeyer flask containing 100 mL medium at ± 30 °C with continuous illumination (± 14 µmol-1 m-2 s-1) andup to 20 d of cultivations. Results demonstrated that on the chromatogram, the highest retention achieved is belong to palmitic acid (C16:0). Chlamydomonas incerta (C. incerta) species is found to contain shorter chain fatty acids, mainly 16 - 18 carbon length, which is ideal for biodiesel production. FTIR spectrum of POME treated biomass displayed the shifting of peak at 591 cm-1 and also removal of C-Cl stretching. The spectrum of POME effluent treated biomass revealed broad peak at 3,430 cm-1. The results of SEM micrographs showed that, after treating POME with C. incerta, the cells became slightly rough and corrugated textures and some particles were found on the surface of the cell wall. Using POME as a rich carbon and nutrient source is also a promising approach either as natural environment treatment or as high-lipid-content raw material for production of biofuel.

Contrasting fish size distributions between Neotropical run-of-river and storage reservoirs

The spectrum size has been used to assess environmental disturbances and to understanding the energy flow in ecosystems. The objective of this work was to investigate if the operation regimes of reservoirs, including run-of-river and storage systems, interfere with the biomass spectra of fish fauna. We tested the hypothesis that the run of river reservoirs present higher proportions of large individuals than storage system. Samplings of fish fauna were carried out between January 2005 and December 2007 at six Neotropical reservoirs belonging to the sub-basin Iguacu River and Coastal basin in Sao Jorge River, Brazil. The spectrum calculation was performed using the Pareto type I continuous distribution model. Reservoirs operated under run-of-river regime had significantly higher values than those operated under storage regimes. This study has elucidated some impacts of reservoir operating regime on biomass spectra and indicated differences in size spectra of fish assemblages among the sampled reservoirs. Therefore, it is important to incorporate management plans that take dam operating mode into account so that conservation of aquatic fauna, especially fish, is more effective.

The bat-bird-bug battle: daily flight activity of insects and their predators over a rice field revealed by high-resolution Scheimpflug Lidar.

We present the results of, to our knowledge, the first Lidar study applied to continuous and simultaneous monitoring of aerial insects, bats and birds. It illustrates how common patterns of flight activity, e.g. insect swarming around twilight, depend on predation risk and other constraints acting on the faunal components. Flight activity was monitored over a rice field in China during one week in July 2016, using a high-resolution Scheimpflug Lidar system. The monitored Lidar transect was about 520 m long and covered approximately 2.5 m3. The observed biomass spectrum was bimodal, and targets were separated into insects and vertebrates in a categorization supported by visual observations. Peak flight activity occurred at dusk and dawn, with a 37 min time difference between the bat and insect peaks. Hence, bats started to feed in declining insect activity after dusk and stopped before the rise in activity before dawn. A similar time difference between insects and birds may have occurred, but it was not obvious, perhaps because birds were relatively scarce. Our observations are consistent with the hypothesis that flight activity of bats is constrained by predation in bright light, and that crepuscular insects exploit this constraint by swarming near to sunset/sunrise to minimize predation from bats.

Environmental Effects on Mesozooplankton Size Structure and Export Flux at Station ALOHA, North Pacific Subtropical Gyre

AbstractUsing size‐fractionated mesozooplankton biomass data collected over 23 years (1994–2016) of increasing primary production (PP) at station ALOHA (A Long‐Term Oligotrophic Habitat Assessment), we evaluate how changing environmental conditions affect mesozooplankton size structure, trophic cycling, and export fluxes in the subtropical North Pacific. From generalized additive model analysis, size structure is significantly influenced by a nonlinear relationship with sea surface temperature that is mainly driven by the strong 1997–1998 El Niño and a positive and linear relationship with PP. Increasing PP has more strongly enhanced the biomass of smaller (0.2–0.5 mm) and larger (>5 mm) mesozooplankton, increasing evenness of the biomass spectra, while animals of 2–5 mm, the major size class for vertically migrating mesozooplankton, show no long‐term trend. Measured PP is sufficient to meet feeding requirements that satisfy mesozooplankton respiration and growth rates, as determined by commonly used empirical relationships based on animal size and temperature, consistent with a tightly coupled food web with one intermediate level for protistan consumers. Estimated fecal pellet production suggests an enhanced contribution of mesozooplankton to passive particle export relative to the material collected in 150 m sediment traps. In contrast, the biomass of vertically migrants does not vary systematically with PP due to the varying responses of the different size classes. These results illustrate some complexities in understanding how varying environmental conditions can affect carbon cycling and export processes at the community level in open‐ocean oligotrophic systems, which need to be confirmed and better understood by process‐oriented mechanistic study.

Transformations to reduce the effect of particle size in mid-infrared spectra of biomass.

Fourier Transform InfraRed (FTIR) spectroscopy is a very powerful technique for the characterization of the chemical composition of biomass and its modifications occurring during thermochemical and chemical pretreatments. However, method development is necessary to generate reproducible signals that can be used in combination with multivariate techniques (such as principal component analysis, PCA) to extract meaningful information on biomass composition and bond cleavage. Particle size is a great source of spectra variability in FTIR of biomass. The FTIR signal for an array of particle sizes (2-0.075 mm) was evaluated for hardwood and switchgrass, revealing that 0.5 mm renders higher intensity and spectral reproducibility for both the FTIR sampling techniques investigated (ATR and HTS-XT). Furthermore, the suitability of different signal processing approaches to decrease particle size variability of spectral signals was tested (signal normalization, derivation, and their combination). Normalization showed the highest contribution to enhance ATR spectral reproducibility of both biomass, as statistically shown by the 5-fold decrease of the ratio of signal variance with magnitude of spectral features (VM ratio) with respect to the unprocessed signal. Spectral signal analysis in combination with multivariate statistics (PCA) was used to extract information about the chemical differences between hardwood and switchgrass. The agreement of the biomass composition findings from FTIR-PCA and literature wet chemistry results (acid hydrolysis) contributed to corroborating that FTIR combined with PCA is a clean, quick, efficient, and versatile technique with potential to analyze and characterize biomass composition.

Assessment of heavy metal tolerance and biosorptive potential of Klebsiella variicola isolated from industrial effluents

Heavy metal contamination now a day is one of the major global environmental concerns. Textile effluents of Faisalabad Pakistan are heavily contaminated with heavy metals and demands to explore native microorganisms as effective bioremediation tool. Study aimed to isolate heavy metal tolerant bacteria from textile effluents of Faisalabad Pakistan and to evaluate their biosorptive potential. Out of 30 collected samples 13 isolates having metal tolerance potential against Ni and Co were screened out. Maximum tolerable concentration and multi metal resistance was determined. A native bacterial strain showing maximum tolerance to Ni and Co and multi metal resistance against Ni, Co and Cr at different levels was selected and named as Abuzar Microbiology 1 (AMIC1). Molecular characterization confirmed it as Klebsiella variicola which was submitted in First fungal culture bank of Pakistan (FCBP-WB-0688). ICP-OES revealed that it reduced Ni (50, 49%) and Co (71, 68.6%) after 24 and 48 h, respectively. FT-IR was used to analyze functional groups and overall nature of chemical bonds. Changes in spectra of biomass were observed after absorption of Ni and Co by K. variicola. SEM revealed morphological changes in bacteria in response to metal stress. Both metals affected bacterial cell wall and created pores in it. However effect of Ni was more pronounced than Co. It was concluded that K. variicola, a native novel strain possessed significant heavy metal tolerance and bioremediation potential against Ni and Co. It may be used in future for development of bioremediation agents to detoxify textile effluents at industrial surroundings.

Trophic diversity, size and biomass spectrum of Bay of Bengal nematodes: A study case on depth and latitudinal patterns

Depth and latitudinal patterns of nematode functional attributes were investigated from 35 stations of Bay of Bengal (BoB) continental shelf. We aim to address whether depth and latitudinal variations can modify nematode community structure and their functional attributes (trophic diversity, size and biomass spectra). Global trend of depth and latitudinal related variations have also been noticed from BoB shelf in terms of nematode abundance and species richness, albeit heterogeneity patterns were encountered in functional attributes. Index of trophic diversity values revealed higher trophic diversity across the BoB shelf and suggested variety of food resource availability. However, downstream analysis of trophic status showed depth and latitude specific patterns but not reflected in terms of size and biomass spectrum. The peaks at different positions clearly visualized heterogeneity in distribution patterns for both size and biomass spectrum and also there was evidence of availability of diversified food resources. Nematode biomass spectra (NBS) constructed for nematode communities showed shift in peak biomass values towards lower to moderate size classes particularly in shallower depth but did not get reflected in latitudes. However, Chennai and Parangipettai transects demonstrated shift in peak biomass values towards higher biomass classes explaining the representation of higher nematode abundance. Our findings concluded that depth and latitudes are physical variables; they may not directly affect nematode community structure and functional attributes but they might influence the other factors such as food availability, sediment deposition and settlement rate. Our observations suggest that the local factors (seasonal character) of phytodetrital food flux can be very important for shaping the nematode community structure and success of nematode functional heterogeneity patterns across the Bay of Bengal shelf.

Size-based indicators show depth-dependent change over time in the deep sea

Abstract Size-based indicators are well established as a management tool in shelf seas as they respond to changes in fishing pressure and describe important aspects of community function. In the deep sea, however, vital rates are much slower and body size relationships vary with depth, making it less clear how size-based indicators can be applied and whether they are appropriate for detecting changes through time. The deep-sea fish stocks of the North Atlantic underwent a period of exploitation followed by management and conservation action that relieved this pressure. We used data from a deep-water bottom trawl survey in the Rockall Trough, at depths of 300–2000 m, to test whether size-based indicators changed over a 16-year period, during which fishing pressure decreased. We applied four indicators to these data: mean body length, mean maximum length, large fish indicator (LFI), and the slope of the biomass spectrum. Patterns were analysed within four different depth bands. The LFI and slope of the biomass spectrum showed positive change over time, suggesting recovery from fishing pressure. This response was generally most apparent in the shallowest depth band, where most fishing activity has been distributed. Values of the LFI were much higher overall than in shelf seas, so the same reference points cannot be applied to all marine ecosystems. These findings imply that size-based indicators can be usefully applied to the deep sea and that they potentially track changes in fishing pressure in the medium term.

Contextualizing macroecological laws: A big data analysis on electrofishing and allometric scalings in Ohio, USA

We investigated the influence of different electrofishing methods on allometric scaling features of fish assemblages in lotic environments. The ultimate aim was to elucidate to which extent the structure of fish assemblages is predictable by the three-quarter power law theory. Water bodies across the state of Ohio, USA, provided a suitable data set to analyze the size–biomass spectra of 2051 fish assemblages. For the first time, 41,070 allometric field observations were screened according to sampling methods (i.e., longline, tote barge, boat) adopted for sampling collection. Allometric patterns varied considerably in relation with the sampling method, in turn imposed by the local hydrology and morphology of the investigated water courses, as shown by the lowering of scalings from boatable to wadeable systems. There are several lines of evidence indicating that the chosen type of electrofishing acts as a pitfall for size spectra. Using individually weighted body-mass values as independent predictor of spectra we show that the specific sampling methodology required by the physical characteristics of different lotic habitats influence the allometric outcomes, a novel result that makes universality of community power laws not as straightforward as supposed until now.

Reviving Pretreatment Effectiveness of Deep Eutectic Solvents on Lignocellulosic Date Palm Residues by Prior Recalcitrance Reduction

Deep eutectic solvents (DESs), featured as promising green solvents, have increasingly drawn attention in the processing of a wide spectrum of lignocellulosic biomass (e.g., corn stover, wheat straw, and rice straw). However, the ineffectiveness of enhancing enzymatic digestibility of lignocellulosic date palm residues by pretreatment using DESs (choline chloride/glycerol) only was observed in this study. Inspired by the different observation with counterparts, it was hypothesized that the recalcitrance of date palm residues caused the ineffectiveness. A novel approach of reducing recalcitrance of biomass through hydrothermal pretreatment prior to DESs treatment was proposed to revive the effectiveness of DESs on enhancing cellulose digestibility. The results showed that hydrothermal treatment effectively triggered the functioning of choline chloride/glycerol to boost enzymatic digestibility (1.7 times increase) of date palm residues. In addition, this study indicated that the significant increases of bot...

Nematode morphometry and biomass in the Saigon River harbours in relation to antifouling contaminants

Morphometry and biomass of nematode communities in different harbours of the Saigon River were investigated in the dry and wet seasons in relation to environmental variables such as total organic carbon, pH, conductivity, salinity and oxygen redox potential, in addition to concentrations of different butyltin compounds. The results indicated that nematodes in contaminated sediments from the Saigon River harbours were mainly characterised by slender morphotypes, whilst very few thin and stout nematodes were observed. Individual nematode biomass was generally low, especially in the wet season. There was no significant correlation between butyltin compounds and nematode morphometrics in the dry season but significant correlations were found for the wet season. Although significant correlations were observed for the wet season, the strong seasonal differences in nematode biomass spectra suggest a potential limitation in their use for environmental monitoring.

Using solid 13C NMR coupled with solution 31P NMR spectroscopy to investigate molecular species and lability of organic carbon and phosphorus from aquatic plants in Tai Lake, China.

Forms and labilities of plant-derived organic matters (OMs) including carbon (C) and phosphorus (P) were fundamental for understanding their release, degradation and environmental behaviour in lake ecosystems. Thus, solid 13C and solution 31P nuclear magnetic resonance (NMR) spectroscopy were used to characterize biomass of six aquatic plants in Tai Lake, China. The results showed that carbohydrates (61.2% of the total C) were predominant C functional group in the solid 13C NMR spectra of plant biomass, which may indicate high lability and bioavailability of aquatic plants-derived organic matter in lakes. There was 72.6-103.7% of the total P in aquatic plant biomass extracted by NaOH-EDTA extracts. Solution 31P NMR analysis of these NaOH-EDTA extracts further identified several molecular species of P including orthophosphate (50.1%), orthophosphate monoesters (46.8%), DNA (1.6%) and pyrophosphate (1.4%). Orthophosphate monoesters included β-glycerophosphate (17.7%), hydrolysis products of RNA (11.7%), α-glycerophosphate (9.2%) and other unknown monoesters (2.1%). Additionally, phytate, the major form of organic P in many lake sediments, was detected in floating plant water poppy. These inorganic P (e.g. orthophosphate and pyrophosphate) and organic P (e.g. diester and its degradation products) identified in plant biomass were all labile and bioavailable P, which would play an important role in recycling of P in lakes. These results increased knowledge of chemical composition and bioavailability of OMs derived from aquatic plants in lakes.

Size-structural shifts reveal intensity of exploitation in coral reef fisheries

Fisheries exploitation represents a considerable threat to coral reef fish resources because even modest levels of extraction can alter ecological dynamics via shifts of stock size, species composition, and size-structure of the fish assemblage. Although species occupying higher trophic groups are known to suffer the majority of exploitative effects, changes in composition among lower trophic groups may be major, though are not frequently explored. Using size-based biomass spectrum analysis, we investigate the effects of fishing on the size-structure of coral reef fish assemblages spanning four geopolitical regions and determine if patterns of exploitation vary across trophic groups. Our analyses reveal striking evidence for the variety of effects fisheries exploitation can have on coral reef fish assemblages. When examining biomass spectra across the entire fish assemblage we found consistent evidence of size-specific exploitation, in which large-bodied individuals experience disproportionate reductions. The pattern was paralleled by and likely driven by, strongly size-specific reductions among top predators. In contrast, evidence of exploitation patterns was variable among lower trophic groups, in many cases including evidence of reductions across all size classes. The breadth of size classes and trophic groups that showed evidence of exploitation related positively to local human population density and diversity of fishing methods employed. Our findings highlight the complexity of coral reef fisheries and that the effects of exploitation on coral reefs can be realized throughout the entire fish assemblage, across multiple trophic groups and not solely restricted to large-bodied top-predators. Size-specific changes among fishes of lower trophic groups likely lead to altered ecological functioning of heavily exploited coral reefs. Together these findings reinforce the value of taking a multi-trophic group approach to monitoring and managing coral reef fisheries.

Modifying the functional diversity in the zooplankton assemblage of an oligotrophic lake differentially affects pelagic community structure and biomass

Experimental ecology represents a fundamental tool to predict how a system reacts to the loss of functional groups in response to contingent disturbance.Zooplankton, the heart of pelagic food webs, is characterized by short life cycles; therefore it can serve as a model system to test ecological theories.In this study we performed a removal experiment to test the hypothesis that the absence of calanoid or cyclopoid copepods could have a different effect on plankton dynamics due to their distinct functional roles in freshwater ecosystems.We selectively removed either Calanoida or Cyclopoida from the original zooplankton assemblage of the oligotrophic lake Brunnsee (Bavaria, Germany), then inspecting temporal changes in plankton community structure and biomass. Experimental communities were incubated in plastic enclosures, fed with cultured phytoplankton and analysed at four time steps over four weeks.Our manipulations led to significant variations in environmental parameters (i.e. chlorophyll-a and microalgae concentration), in zooplankton community composition (dominance, diversity and equitability) and in normalized biomass spectra of zooplankton. The main driver of such changes was the small cladoceran Ceriodaphnia reticulata, the most abundant species at the final sampling in all the treatments. Calanoida facilitated the development of C. reticulata; Cyclopoida played a keystone role, indirectly regulating the abundance of this cladoceran through predation on Calanoida.Our results offer a wider picture of the pelagic food web in oligotrophic freshwater environments and strongly support the view that ecological studies should rely on the measurement of both specific and functional diversity.

The paradox of inverted biomass pyramids in kelp forest fish communities.

Theory predicts that bottom-heavy biomass pyramids or 'stacks' should predominate in real-world communities if trophic-level increases with body size (mean predator-to-prey mass ratio (PPMR) more than 1). However, recent research suggests that inverted biomass pyramids (IBPs) characterize relatively pristine reef fish communities. Here, we estimated the slope of a kelp forest fish community biomass spectrum from underwater visual surveys. The observed biomass spectrum slope is strongly positive, reflecting an IBP. This is incongruous with theory because this steep positive slope would only be expected if trophic position decreased with increasing body size (consumer-to-resource mass ratio, less than 1). We then used δ(15)N signatures of fish muscle tissue to quantify the relationship between trophic position and body size and instead detected strong evidence for the opposite, with PPMR ≈ 1650 (50% credible interval 280-12 000). The natural history of kelp forest reef fishes suggests that this paradox could arise from energetic subsidies in the form of movement of mobile consumers across habitats, and from seasonally pulsed production inputs at small body sizes. There were four to five times more biomass at large body sizes (1-2 kg) than would be expected in a closed steady-state community providing a measure of the magnitude of subsidies.

The ecological module of BOATS-1.0: a bioenergetically constrained model of marine upper trophic levels suitable for studies of fisheries and ocean biogeochemistry

Abstract. Environmental change and the exploitation of marine resources have had profound impacts on marine communities, with potential implications for ocean biogeochemistry and food security. In order to study such global-scale problems, it is helpful to have computationally efficient numerical models that predict the first-order features of fish biomass production as a function of the environment, based on empirical and mechanistic understandings of marine ecosystems. Here we describe the ecological module of the BiOeconomic mArine Trophic Size-spectrum (BOATS) model, which takes an Earth-system approach to modelling fish biomass at the global scale. The ecological model is designed to be used on an Earth-system model grid, and determines size spectra of fish biomass by explicitly resolving life history as a function of local temperature and net primary production. Biomass production is limited by the availability of photosynthetic energy to upper trophic levels, following empirical trophic efficiency scalings, and by well-established empirical temperature-dependent growth rates. Natural mortality is calculated using an empirical size-based relationship, while reproduction and recruitment depend on both the food availability to larvae from net primary production and the production of eggs by mature adult fish. We describe predicted biomass spectra and compare them to observations, and conduct a sensitivity study to determine how they change as a function of net primary production and temperature. The model relies on a limited number of parameters compared to similar modelling efforts, while retaining reasonably realistic representations of biological and ecological processes, and is computationally efficient, allowing extensive parameter-space analyses even when implemented globally. As such, it enables the exploration of the linkages between ocean biogeochemistry, climate, and upper trophic levels at the global scale, as well as a representation of fish biomass for idealized studies of fisheries.

Plant growth promotion by Bradyrhizobium japonicum under heavy metal stress

The increase in usage of heavy metals in different industrial activities causes their existence in effluents. Excessive concentrations of these heavy metals pollute soil and water. Heavy metals cause toxicities and other harmful effects not only in humans and animals but also in plants and soil microorganisms. Heavy metals disrupt many biochemical and physiological activities in bacteria, including growth, development, enzyme and hormone production. Indole acetic acid (IAA) is one of the most important hormones in plants, which is secreted by both bacteria and plants. The present study assessed the effects of Ni, Pb and Cu on the growth of Bradyrhizobium japonicum and IAA production.B. japonicum were grown in yeast mannitol broth in a rotary shaker at 100rpm for 18h for each variant. Ni, Pb and Cu with concentrations ranging from 2.5–40mg/L were added to B. japonicum cultures and turbidity was measured at 600nm. Effects of Ni, Pb and Cu on IAA production were determined by measuring the IAA content with Salkowski method. The metal uptake by B. japonicum was determined in the range of 5–50mg/L. A lettuce seedling assay was conducted to observe the effect of B. japonicum on plant growth under heavy metal stress. Lettuce seedlings inoculated with the bacterium were spiked with 5–500mg/L of Ni, Pb and Cu. Shoot and root length, and plant dry biomass were measured after 5days of germination.Bacterial growth was reduced with the increase of Ni and Cu concentrations. However, there was no significant growth effect with Pb in the considered range. The IAA production also followed the same pattern with Pb and Ni, but in the presence of Cu, IAA content was slightly increased and reached an equilibrium. The growth retardations observed in lettuce in the presence of Pb, Ni and Cu were in the decreasing order of Ni>Cu>Pb. Bacterial inoculation reduced the heavy metal stress and increased the shoot and root lengths of lettuce seedlings. FTIR spectrum of the bacterial biomass showed that amine and nitro groups are responsible in metal sorption process. The Pb-treated bacterial biomass showed a considerable difference in the FTIR spectrum compared to other treatments. According to our results, B. japonicum is sensitive to heavy metal stress with a retardation of growth and IAA production, though it is able to enhance the growth of lettuce seedlings under heavy metal stress.

Surfing the biomass size spectrum: some remarks on history, theory, and application

Charles Elton introduced the “pyramid of numbers” in the late 1920s, but this remarkable insight into body-size dependent patterns in natural communities lay fallow until the theory of the biomass size spectrum was introduced by aquatic ecologists in the mid-1960s. They noticed that the summed biomass concentration of individual aquatic organisms was roughly constant across equal logarithmic intervals of body size from bacteria to the largest predators. These observations formed the basis for a theory of aquatic ecosystems, based on the body size of individual organisms, that revealed new insights into constraints on the structure of biological communities. In this review, we discuss the history of the biomass spectrum and the development of underlying theories. We indicate how to construct biomass spectra from sample data, explain the mathematical relations among them, show empirical examples of their various forms, and give details on how to statistically fit the most robust linear and nonlinear models to biomass spectra. We finish by giving examples of biomass spectrum applications to production and fisheries ecology and offering recommendations to help standardize use of the biomass spectrum in aquatic ecology.