Search

The properties of rice husk biochar during the ageing process in soil and the resulting impacts on sorption capacity with respect to Cu(ii) were assessed. Rice husk-derived biochar was placed in fabric bags and buried in a plastic incubator filled with soil for 0–240 d. The aged biochar was then characterised and its sorption capacity compared with control (unaged) biochar in batch sorption experiments. The structural composition and morphology of the biochar before and after ageing were analysed based on element composition, scanning electron microscopy (SEM) coupled with energy X-ray dispersive spectroscopy (EDS), diffuse reflectance infrared Fourier transform infrared spectroscopy (DRIFTS), and X-ray photoelectron spectroscopy (XPS). The concentration of O, atomic O/C ratios, and carboxyl and hydroxyl functional groups increased at the surface of the biochar during ageing, which together indicated oxidation. Within the biochar particles, O/C ratios progressively increased towards their outer surfaces. Furthermore, ageing for more than 120 d facilitated Cu(ii) sorption as oxygen-containing groups were able to develop. The maximum adsorption capacity (qm) of biochar increased by 1.24 ∼ 1.32 times after ageing in the soil for 240 d. It is suggested that biochar surface properties were gradually altered during environmental exposure and the aged rice husk biochar showed increased performance in Cu(ii) adsorption. However, the performance of aged biochar as a soil remediator or conditioner will be affected by the ageing process and interactions among different soil components. As such, further research is required to evaluate these complex effects.

Karst, written by J.N. (Joseph Newell) Jennings in the series entitled An Introduction to Systematic Geomorphology, provided a systematic introduction to the geomorphological features of karst and the processes by which it is formed. The many distinctive features of karst geomorphology are formed by the unusual solubility of the bedrock. Understanding the special nature of karst geomorphology is an important foundation for current critical zone studies that are aimed at comprehending the sophisticated linkage between lithosphere, hydrosphere, biosphere and atmosphere in a karst region.

The role of bedrock geochemistry in vegetation growth within karst areas has been examined in recent works, implying that the approach of the critical zone (CZ) extending from the canopy to the groundwater bottom enhances the understanding of vegetation ecology. In this paper, the research progress of vegetation ecology associated with bedrock features in the karst CZ in subtropical Southwest China is systematically reviewed. There are great differences in soil formation and soil features (water-holding capacity, particle size, and soil chemistry) between karst and non-karst regions, even between dolomite and limestone within a karst region. Water and soil are easily leached due to the connected underground crevices in karst, particularly in limestone-dominated regions, leading to water deficits in karst CZ plants in subtropical Southwest China. The development of plant roots in crevices affects the water and nutrient absorption by plants and microbial activities in the soil, which form the basis for vegetation distribution and growth in the karst CZ. The organic acids from plants also increase weathering rates. As extensive human activities have accelerated vegetation degradation and soil erosion and further led to rocky desertification characterized by increasing areas of rock exposure, state-of-the-art knowledge about the effects of bedrock-associated belowground and aboveground interactions can guide the implementation of vegetation restoration and the control of further rocky desertification in the subtropical karst CZ.

Tree allometry in semi-arid forests is characterized by short height but large canopy. This pattern may be important for maintaining water-use efficiency and carbon sequestration simultaneously, but still lacks quantification. Here we use terrestrial laser scanning to quantify allometry variations of Quercus mongolica in semi-arid forests. With tree height (Height) declining, canopy area (CA) decreases with substantial variations. The theoretical CA-Height relationship in dynamic global vegetation models (DGVMs) matches only the 5th percentile of our results because of CA underestimation and Height overestimation by breast height diameter (DBH). Water supply determines Height variation (P = 0.000) but not CA (P = 0.2 in partial correlation). The decoupled functions of stem, hydraulic conductance and leaf spatial arrangement, may explain the inconsistency, which may further ensure hydraulic safety and carbon assimilation, avoiding forest dieback. Works on tree allometry pattern and determinant will effectively supply tree drought tolerance studying and support DGVM improvements., Jingyu Dai et al. study the role of tree allometry in maintaining a high carbon sequestration. They measure allometry in semi-arid forests using terrestrial laser scanning. They report that tree height as well as canopy area decline to varying degrees among individuals. They provide insights on how trees balance water consumption and carbon assimilation which enhances the survival rate of the forest trees.

Funder: Agua Salud Project, Funder: U.S. Department of Energy; Id: http://dx.doi.org/10.13039/100000015, Funder: CAPES; Id: http://dx.doi.org/10.13039/501100002322, Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research-from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non-forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC-BY 4.0 licence and can be access from: https://doi.org/10.5281/zenodo.6637599. To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology-from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle.

Hemiboreal and boreal forests growing at the southern margin of the permafrost distribution are vulnerable to climate warming. However, how climate warming threatens the growth of dominant tree species that are distributed on permafrost remains to be determined, particularly in synchrony with warming-induced permafrost degradation. Tree growth in the permafrost region of southern Siberia was hypothesized to be highly sensitive to temperature increasing and warming-induced permafrost degradation. To test this hypothesis, we sampled the tree ring width of 535 trees of dominant species, larch (including Larix gmelinii and L. sibirica) and white birch (Betula platyphylla), in ten hemiboreal to boreal forest plots within different permafrost zones. The relationships between the tree ring basal area index (BAI) and temperature, precipitation, and the Palmer drought severity index (PDSI) were compared among plots located in two permafrost zones. In the isolated permafrost zone, white birch grows better than larch and is not drought-stressed (p .05). We suggest that the deep-rooted white birch benefits from the water from thawing permafrost, while the growth of the shallow-rooted larch is stressed by drought. In the sporadic discontinuous permafrost zone, both white birch and larch benefited from permafrost melting, but the sensitivity of larch growth to PDSI is still significant (p .05), indicating drought is still an important climatic factor limiting the growth of larch. Our results imply that the permafrost degradation caused by climate warming affects tree growth by creating the root layer additional water source. In the future, it is necessary to focus on monitoring permafrost degradation to better predict forest dynamics at the southern margin of the permafrost distribution.

The present study designs a wearable smart device regarding relationship between temperature and emotion. The device, amplifies, and sub-regionally transmits the current generated by the body temperature thermoelectric generator through a smart body temperature sensor. Different areas of clothing produce controllable and intelligent color, so that adult emotions can be understood through changes in clothing colors, which is conducive to judging their moods and promoting social interaction. Experimental results show that the device can accurately detect changes in human body temperature under hilarious, fearful, soothing, and angry emotions, so as to achieve changes in clothing colors, namely blue, red, green, and brown.

Catalytic NO oxidation is crucial in oxidizing soot and promoting NH3 reduction during the emission eliminations of diesel vehicles by the modern after-treatment systems. To create more active oxygen species in favor of NO oxidation, ceria-modified monolithic Pt-based diesel oxidation catalyst was prepared by the step-impregnation method to improve its NO catalytic performance. Its NO maximum conversion was up to around 60% in the gas hourly space velocity of 60 kh−1. Experimental results suggested that the ceria addition could have a better dispersion due to the inhibition effect of platinum aggregation. Especially, it is found that more active oxygen and oxygen vacancies over the catalyst played a significant role in strengthening the interaction of NO molecule with catalyst surface, resulting in the formation and transformation of more bridging/chelating nitrates confirmed by in situ FTIR studies. After thermal ageing, the catalyst with ceria addition still enabled a excellent NO catalytic performance, up to 50% NO maximum conversion. It would be proposed that active oxygen from the interaction bewteen ceria and Pt improved its NO catalytic activity and thermal-stability.

There are less than 10% of woody species that can have both tree and shrub growth forms globally. At the xeric timberline, we observed the tree-to-shrub shift of the Quercus mongolica Fisch. ex Ledeb.. Few studies have explored the underlined mechanism of this morphological transition of tree-to-shrub in arid regions. To examine whether the tree-to-shrub shift affects carbohydrate allocation and to verify the effect of life stage on non-structural carbohydrate (NSC) storage, we measured the concentration of soluble sugar and starch of Q. mongolica in the seedlings, saplings, and adult trees by selecting two sites with either tree or shrub growth forms of Q. mongolica at the driest area of its distribution. Accordingly, there was no significant difference in the radial growth with different growth forms (p > 0.05). The results showed that the effects of growth form on NSC concentrations are significant in the seedling and sapling stages, but become less pronounced as Q. mongolica grows. The results of the linear mixed model showed that life stage has a significant effect on soluble sugar concentration of tree-form (p < 0.05), starch and TNC concentration of shrub-form (p < 0.05). Compared with a shrub form without seedling stage, a tree form needs to accumulate more soluble sugar from seedling stage to adapt to arid environment. Saplings and adult shrubs store more starch, especially in thick roots, in preparation for sprout regeneration. Our study shows that the same species with tree and shrub forms embody differentiated carbohydrate allocation strategies, suggesting that shrub form can better adapt to a drier habitat, and the tree-to-shrub shift can benefit the expansion of woody species distribution in dryland.

Considering the global demands in sustaining agriculture, use of organic amendments is gradually increasing. An improved understanding of the biological process is essential to evaluate the performance of organic amendments on agro-ecosystem. Soils subjected to different fertilization regimes were collected from a field experiment. Microbial community compositions are assessed with 16S and ITS rRNA gene sequencing and subsequent bioinformatics analysis. Microbial functions are characterized with the geometric mean of the assayed enzyme activities (GMea) and the microbial carbon-use efficiency:nitrogen-use efficiency ratio (CUE:NUE). Compared with the chemically fertilized soil, the GMea significantly increased in organically amended soils. In contrast, the CUE:NUE was highest in chemically treated soil. These changes of microbial functional indicators were associated with shifts in the bacterial and not the fungal community composition, despite the fact that both the bacterial and fungal community compositions were significantly affected by the fertilization regimes. The abundances of specific soil bacterial taxa, especially the genera Luteimonas and Gemmatimona, were enriched by organic amendments. Soil organic carbon emerged as the major determinant of the bacterial community composition. Soil microbial activities and nutrient-use efficiencies were dramatically changed along with the alteration of bacterial community composition. Relatively greater abundance of Luteimonas and Gemmatimona taxa in soils might be useful indicators for soil amelioration. Our research could be helpful to provide better strategies for the maintenance of soil fertility.

Semiarid forests characterized by the presence of “trub” species, which have short heights but large canopy sizes, can maintain a high carbon sequestration rate. By integrating terrestrial laser scanning (TLS), we quantified drought-forced tree morphological variation along a precipitation gradient; annual precipitation (MAP) explained 70.3% of variation in tree height (Height) but did not explain the variation in canopy area (CA). Theoretical CA-Height relationships widely adopted by dynamic global vegetation models (DGVMs) matched only the 5th percentile of our results, which is problematic for simulating carbon sequestration of open forests in semiarid regions. The trend toward “trubs” under a drying climate implies two decoupled functions of stems, mechanical stability and hydraulic efficiency, and can be an important strategy for trees to balance water and carbon. Our results demonstrate the importance of tree morphological studies for both tree environment-acclimation strategies and the improvement of DGVMs.

In September 2015, the State Council of the People’s Republic of China issued the “Action Outline for Big Data Development” approved by the Premier, Li Keqiang, and systematically deployed the development of big data to meet the new opportunities and challenges brought by the big data technology revolution. In the field of education, more and more schools find that in curriculum design, it is necessary to introduce the proposition of science and technology and fashion, which is expressed in three-dimensional software.

Herein, we have described the important role about biochar aging on the basis of sorption performance of phenanthrene. Biochar used in this study was produced from rice husks at 350 °C and its aging has been manufactured by laboratory incubation. The results showed that an aging layer formed which contains oxygen-bearing groups on to the surface increased during the course of aging. Aging decreased the adsorption capability of biochar obtained under low temperature by 34.10%, ascribed as the increase of oxygen bearing polar moieties; specifically the hydroxyl species that negatively affected sorption of phenanthrene.

Research Highlights: Answering how tree hydraulic strategies explain the interspecific associations of co-occurring trees in forest&ndash, steppe ecotone is an approach to link plant physiology to forest dynamics, and is helpful to predict forest composition and function changes with climate change. Background and Objectives: The forest&ndash, steppe ecotone&mdash, the driest edges of forest distribution&mdash, is continuously threatened by climate change. To predict the forest dynamics here, it is crucial to document the interspecific associations among existing trees and their potential physiological drivers. Materials and Methods: Forest&ndash, steppe ecotone is composed of forest and grassland patches in a mosaic pattern. We executed two years of complete quadrat surveys in a permanent forest plot in the ecotone in northern China, calculated the interspecific association among five main tree species and analyzed their hydraulic strategies, which are presented by combining leaf-specific hydraulic conductivity (Kl) and important thresholds on the stem-vulnerability curves. Results: No intensive competition was suggested among the co-occurring species, which can be explained by their divergent hydraulic strategies. The negative associations among Populus davidiana Dode and Betula platyphylla Suk., and P. davidiana and Betula dahurica Pall. can be explained as the result of their similar hydraulic strategies. Tilia mongolica Maxim. got a strong population development with its effective and safe hydraulic strategy. Generally, hydraulic-strategy differences can explain about 40% variations in interspecific association of species pairs. Oppositely, species sensitivity to early stages of drought is convergent in the forest. Conclusions: The divergent hydraulic strategies can partly explain the interspecific associations among tree species in forest&ndash, steppe ecotone and may be an important key for semiarid forests to keep stable. The convergent sensitivity to early stages of drought and the suckering regeneration strategy are also important for trees to survival. Our work revealing the physiological mechanism of forest compositions is a timely supplement to forest&ndash, steppe ecotone vegetation prediction.

Natural organic matter (NOM) contains a large number of aromatic ketones and quinones, which can produce reactive oxygen species (ROS), such as 1O2 and HO·, through photosensitization. These ROS play important roles in the attenuation of organic pollutants in sunlit surface water. The NOM components fractionated with XAD-8 resin at different pH influence the photo-generation of ROS, which may be related to the degree of dissociation of functional groups. In this study, probe chemicals were used to investigate the effect of dissociation degree (pKa) of NOM model compounds on ROS production under 254 nm UV irradiation. Experimental results showed that six model compounds with similar molecular weights and structures but different pKa values have different ROS production abilities in a pH 7.0 reaction system. The ability for DHB2,5 (2.97), DHB3,4 (4.48), and GUA (9.99) to photo-generate 1O2 increased with increasing dissociation. The ability for DHB3,4 and GUA to photo-generate HO· followed the same trend. The correlation between NOM dissociation constant and ROS generation is preliminary established, which explains the influence of functional groups. Our results may provide some basic information for understanding the correlation between NOM structural features and ROS generation.

Increasing industrial development and rapid urbanization affects adversely the paddy regions of China in terms of environmental pollution. Soil organic matter is one of the major components, which influence the contaminants mobility in soils. Fulvic acid is one of the major fractions of the soil organic matter of the paddy soils. It is imperative to separate fulvic acids (FA) to different fractions based on their chemical properties to reduce their heterogeneity and to cognize their environmental behavior. Five FA fractions from two paddy soils were first obtained by eluting FA through XAD-8 resin with sequential eluents (pH 4.8, pH 7.0, and pH 11 buffering solutions, water, and ethanol), and were then characterized by elemental analysis, Fourier-transform infrared (FT-IR) spectroscopy, liquid 1H nuclear magnetic resonance (1H NMR) spectroscopy, and cross-polarization magic-angle spinning 13C nuclear magnetic resonance (CP-MAS 13C NMR) spectroscopy. The results are consistent between the methods used, suggesting that the later eluted fractions (eluted with water or ethanol) in the sequential elution contained lower carboxylic C, and higher alkyl C than the earlier ones. We hope that such fractionation of humic matters would be useful in detail understanding of the interaction between natural organic matter and contaminants.

Biochar exposed in the environment may experience a series of surface changes, which is called biochar aging. In order to study the effects of biochar aging on Cu(II) adsorption, we analyzed the surface properties before and after biochar aging with scanning electron microscopy (SEM) coupled to an energy-dispersive X-ray spectrometer (EDX) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and then explored the influence of the aging process on Cu(II) adsorption by batch experiments. After the aging process, the oxygen concentration, phenolic hydroxyl groups, aromatic ethers and other oxygen-containing functional groups on the biochar surface increased, while carboxyl groups slightly decreased. Thus, over a range of pH, the cation exchange capacity (CEC) and adsorption capacity of Cu(II) on the aged biochar were smaller than those of new biochar, indicating that when biochar is incubated at constant temperature and water holding capacity in the dark, the aging process may inhibit Cu(II) adsorption. Meanwhile, the dissociation characteristics of oxygen-containing functional groups changed through the aging process, which may be the mechanism by which the biochar aging process inhibits the Cu(II) adsorption. Carboxyl groups became more easily dissociated at low pH (3.3–5.0), and the variation of maximum adsorption capability (qm) of Cu(II) on the old biochar was enlarged. Phenolic hydroxyl groups increased after the aging, making them and carboxyl groups more difficult to dissociate at high pH (5.0–6.8), and the variation of qm of Cu(II) on the aged biochar was reduced.

This paper demonstrates the ability of Shear Strength Reduction (SSR) analysis based on the Finite Element Method (FEM) to model the excavations sizes effects of discontinuity networks on the stability and failure mechanisms of slopes in blocky rock masses. Through GuangYang highway slope in k3+980∼k4+240, it shows how these mechanisms depend on joint network geometry and change with increasing slope height.

Fulvic acids extracted from a typical rice-production region near Taihu Lake of China were fractionated into three fractions including F4.8, F7.0 and F11.0 (eluted by pH 4.8 buffer, pH 7.0 buffer and pH 11.0 buffer, respectively). Sorption of fulvic acid (FA) fractions onto kaolinite was studied by batch adsorption experiments, and characterizations of kaolinite before and after adsorption were investigated using scanning electron microscopy (SEM). Adsorption isotherms of kaolinite for three FA fractions fit well with the Langmuir adsorption model. The adsorption density of the three fractions was positively correlated with the ratio of the amount of the alkyl carbon to that of carboxyl and carbonyl carbon in FA fractions and followed an order of F11.0 > F7.0 > F4.8. Hydrophobic interaction was one of the control mechanisms for the sorption of FA fraction onto kaolinite. SEM images confirmed that compared to blank kaolinite samples, kaolinite samples coated by a FA fraction displayed an opener and more dispersed conformation resulting from the disruption of the floc structure in complex. Dispersion of kaolinite after adsorption was due to the repulsion between negatively charged FA-coated particles, which is closely related to the amount of FA fractions absorbed on kaolinite.