Isolation of Nanocellulose from Water Hyacinth Fiber (WHF) Produced via Digester-Sonication and Its Characterization

The successful isolation and characterization of water hyacinth fiber (Eichornia crassipes) (WHF) nanocellulose is presented in this study. The novelty was in exploring a wider range of properties of highly purified samples of WHF after each stage of production in more depth. The isolation was accomplished by pulping in a digester and sonication. Morphological changes before and after treatment were demonstrated by scanning electron microscopy (SEM). The lignin and hemicellulose content decreased during chemical treatment. Transmission electron microscopy (TEM) and particle size analyzer (PSA) were used to determine the morphology of WHF after sonication for 1 h. TEM shows that the diameter and length of nanocellulose WHF were 15.61 and 147.4 nm, respectively. The crystallinity index and crystalline domain area significantly increased after chemical treatment. The highest crystallinity index was 84.87 % after an acid hydrolysis process. The increase in crystallinity leads to good thermal stability. Moisture absorption tests of WHF were carried out before and after treatment. The lowest moisture absorption was in the cellulose fiber after sonication (nanocellulose).     

Effects of ionic surfactants on the aggregate stability and water repellency of silt loam soil

Purpose

With the increase of surfactant usages, more and more concerns were paid on their effects on the physicochemical characteristics of soils. Up to now, only few researches have examined the effects of ionic surfactants on the stability of soil structure and soil water repellency.

Materials and methods

Cetyltrimethyl ammonium bromide (CTAB) as cationic surfactant and sodium dodecyl sulfate (SDS) as anionic surfactant were adopted to investigate their effects on the aggregate stability and water repellency of a silt loam soil which was sampled in Corn High-Tech Park, Huang-Huai-Hai region, China. (1) Aggregate stability: 50 g soil was mixture with 100 mL surfactant solution in a beaker. The concentrations of surfactant solutions were 0 (the blank), 200, 400, 600, 800, 1000, and 2000 mg L^?1, respectively. After 30 min, the soil was sieved and divided into four fraction aggregates. (2) Soil water repellency: the concentrations of surfactant solutions were the same as experiment 1. Forty grams of soil was blended with 80 mL surfactant solution in an aluminum specimen. Drying the water by oven of 40 °C firstly and then by air, the whole period was about 1 week. After that, soil water infiltration and sorptivity were measured.

Results and discussion

Compared to the blank, surfactants increased the amounts of 2–0.25 and <0.053 mm aggregates of the soil and decreased the amounts of 0.25–0.053 mm aggregates of the soil. Surfactants also increased the mean weight diameter (MWD) of the soil. Except the 200 mg L^?1 treatment, CTAB promoted the soil water infiltration. All SDS treatments impeded the soil water infiltration. The soil repellency factor (R) value of the blank was 1.22, lower than the critical value of 1.95, which implied that the soil of blank treatment was free of soil water repellency. For CTAB, only 200 and 400 mg L^?1 treatment’s R were higher than 1.95 while for SDS, all the treatment’s R were higher than 1.95.

Conclusions

Surfactants improved the stability of soil aggregates. Soil treated with CTAB did not show the repellency, whereas SDS treatment resulted in intense water repellency compared with the wettable blank soil. Findings of this study can be used to explain the role of ionic surfactants on soil structure stability as well as on the development of water repellency in lower soil depths.

     

Effect of nitrogen levels on photosynthetic parameters,morphological and chemical characters of saplings and trees in a temperate forest

Exploring the response differences of leaf physiology parameters to enhanced nitrogen deposition between saplings and trees is vital for predicting the variations of terrestrial ecosystem structure and function under future global climate change. In this study, the ecophysiological parameters of saplings and trees of Fraxinus mandshurica Rupr. were measured at different levels of nitrogen addition in a temperate forest. The results show that ecophysiological parameters maximum net photosynthetic rate(P_(max)), apparent quantum efficiency(a), dark respiration(R_d), light saturation point(L_(sp)), photosynthetic nitrogen use efficiency(PNUE),specific leaf area(SLA)and stomatal conductance under saturated light intensity(G_(smax)) were higher in saplings than in trees. These physiological parameters and not N_(leaf)(leaf nitrogen content)led to relatively lower P_(max) and R_d in trees. For both saplings and trees, low and median nitrogen addition(23 and 46 kg ha~(-1)a~(-1)) resulted in significant increases in Pmax, Rd, Lsp, Chl, PNUE, SLA and Gsmax. These parameters tended to decline under high additions of nitrogen(69 kg ha~(-1)a~(-1)),whereas Nleaf was always enhanced with increasing nitrogen. Variations in Pmax and Rd with increasing nitrogen were attributed to variations in the strongly related parameters of, Lsp, Chl, PNUE, SLA and Gsmax. Overall, the response sensitivity of physiological parameters to enhanced nitrogen levels was lower in trees compared with saplings.     

Sprouting characteristics of a subtropical evergreen broad-leaved forest following clear-cutting in Okinawa,Japan

This study explores the sprouting characteristics of an evergreen broad-leaved forest after clear-cutting based on a survey of 1,893 stumps of 62 tree species in Okinawa, Japan. The sprouting capabilities of the stumps varied among tree species. The stumps of 60 species could produce sprouts, while those of the other two species could not. In 10 of the sprouting species, the mean sprout-stem number was higher than 4.0 stems per stump; nine sprouting species showed low sprouting capabilities. Additionally, Castanopsis sieboldii and Schima wallichii, the dominant species, exhibited high sprouting capabilities. Further, the sprouting capabilities varied with stump diameter at breast height (DBH). Stumps with a larger DBH tended to have a higher mean number of sprout stems per stump, higher DBH, and higher tree height than the smaller stumps. The forest stands regenerated by sprouting might recover into a tree community similar to that before clear-cutting.     

Barriers and Opportunities for the Development of Small-scale Forest Enterprises in Europe

The article introduces the background and summarises main research findings of the research articles in this special issue. The focus is on the key issues relevant for forest-based entrepreneurship development in small-scale forestry in relation to both wood and non-wood forest products and services (NWFP&S). The article draws special attention to changing forest ownership, changing owners’ motives and values, and the evolving role of forest owners’ associations in Europe. The paper draws attention to the finding that many small-scale forest owners do not treat their forest as an income-generating asset. The ownership of the forests may be more important as symbolic capital than as a source of income. This is quite opposite to the traditional wood production model that for instance most of the Forest Owners Association’s still follow. In relation to NWFP&S, the taxonomy and indicators for NWFP&S are discussed and some conclusions from studies on forest recreation innovation and NWFP&S marketing are presented. The NWFP&S sector is traditionally product-oriented, which is strategically peculiar because the long distances from rural production areas to the customers would suggest highest orientation on marketing. Also surprising is the low level of segmentation in the sector.

Woody species composition,diversity and structure of riparian forests of four watercourses types in Burkina Faso

Riparian forests are classified as endangered ecosystems in general,particularly in sahelian countries like Burkina Faso because of human-induced alterations and civil engineering works.The modification of this important habitat is continuing,with little attention being paid to the ecological or human consequences of these changes.The objective of this study is to describe the variation of woody species diversity and dynamic in riparian forests on different type of watercourse banks along phytogeographical gradient in Burkina Faso.All woody species were systematically measured in 90 sample plots with sides of 50 m × 20 m.Density,dominance,frequency and species and family importance values were computed to characterize the species composition.Different diver-sity indices were calculated to examine the heterogeneity of riparian forests.A total of 196 species representing 139 genera and 51 families were recorded in the overall riparian forests.The species richness of individuals with dbh ≥ 5cm increased significantly from the North to the South along the phytogeographical gradient and varied significantly between the different types of riparian forests.Similarity in tree species composition between riparian forests was low,which indicates high beta diversity and reflects differences in habitat conditions and topography.The structural characteristics varied significantly along the phyto-geographical gradient and between the different types of riparian forests.The diameter class distribution of trees in all riparian forests showed a reverse "J" shaped curve except riparian forest of stream indicating vegetation dominated by juvenile individuals.Considering the ecological importance of riparian forest,there is a need to delineate and classify them along watercourses throughout the country.     

Semi-Analytical Solutions for Two-Dimensional Transport and Transformation of Contaminants in Soil Medias Associated with Large-Strain Deformation

For the understanding of contaminant transport and transformation through landfill liner soils, most models are proposed with one-dimensional solutions. However, for large-scale contamination analysis, the one-dimensional analytical equations are not valid owing to the restriction of contaminants moving in horizontal direction. Thus, semi-analytical solutions for two-dimensional transport and transformation of contaminants through soil media with the consideration of large-strain deformation have been developed. To achieve this, Gibson’s large-strain consolidation theory is applied to capture the deformation of soil media under loading, with self-weight effects being taken into account. Transport and transformation of dissolved or sorbed contaminates in fully saturated finite soil medias are captured by extending a well-developed advection-dispersion model in two-dimensional space. The proposed analytical solutions are validated through simulating the process of coupled transport-transformation process of contaminants and consolidation of a finite soil layer. Profiles of contaminant concentration for different cases have been compared and discussed. The resulting simulation shows that large-strain deformation would restrict the transport and transformation of contaminants significantly, in both horizontal and vertical directions. Parameter studies also indicate that, with the increasing depth of soil layer, the breakthrough time for contaminants increases dramatically; diffusion coefficients affect the two-dimensional distributions of contaminant concentration and fate of contaminant in layered soil significantly. The numerical findings of this study can provide proper suggestions for the design of landfill liners.     

Cuprous Oxide-Modified Diatomite Waste from the Brewery Used as an Effective Adsorbent for Removal of Organic Dye: Adsorption Performance,Kinetics and Mechanism Studies

Cuprous oxide-modified diatomite waste (Cu₂O-DW) as a low-cost and effective adsorbent was prepared via a hydrothermal route combined with acid-alkali treatment. The microstructure and surface properties of the obtained Cu₂O-DW composite was characterized by Brunauer-Emmett-Teller, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorption behaviors of three different types of dyes such as cationic dye methyl blue (MB), anionic dye acid orange (AO), and reactive dye reactive yellow (RY) onto the as-prepared Cu₂O-DW were investigated. Several experimental parameters such as contact time, adsorbent dosage, initial dye concentration, and initial pH values were systematically estimated. The experimental results indicated that as-prepared Cu₂O-DW have a better adsorption performance for MB, AO, and RY. Moreover, the kinetic and isotherm models were also used to account for the adsorption mechanism of dye molecules onto Cu₂O-DW. The results demonstrated that three different dyes are all fitted well with pseudo-first-order kinetic model. Additionally, the Langmuir and Freundlich isotherm model is more suitable for describing the adsorption process of RY and MB on the as-prepared Cu₂O-DW, respectively, and the AO adsorption is propitious to the D-R isotherm model. The value of adsorption energy (E?<?8 kJ mol^?1) confirmed that the physical adsorption is dominator during the adsorption process. The findings of the study demonstrated that the synthesized Cu₂O-DW composite can be a promising adsorbent for the removal of organic dyes from wastewater and it provided a sustainable development method for cycling the diatomite waste from the brewery.     

Environmental Risk Assessment of Emerging Contaminants Using Degradation Data

The degradation behavior of an emerging contaminant is a key factor in its environmental risk assessment. Existing risk assessment methods based on EC degradation data commonly neglect the time-varying volatility of the degradation, the possible correlations in degradation between different ECs, and the estimation errors. To fill the gaps, this paper proposes an EC risk assessment framework based on the Wiener process. We first focus on degradation data from competitive experiments, which are adopted to evaluate a useful risk indicator, i.e., the bimolecular rate constant of a degradation reaction. A two-dimensional Wiener process model is developed to capture the degradation behaviors of the target EC and a reference contaminant in the experiment. Point and interval estimations of desired quantities, including the rate constant and the degradation half-life, are developed. We further extend the model to the multivariate case, which is applicable to waste water treatment where multiple ECs degrade in a mixed solution. A risk indicator for the mixed solution is proposed, based on which a minimal treatment time can be determined. Both point and interval estimation procedures of the risk indicator and the minimal treatment time are proposed. Two EC degradation datasets are used to demonstrate the proposed methodologies.   Supplementary materials accompanying this paper appear on-line.