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Soil clays (< 2,000 nm) (SC) and soil nanoclays (< 100 nm) (SNC) were used as adsorbents for removal of Cu(II) from aqueous solution. The experiments were conducted with variables including pH, interaction time, concentration of Cu(II) and temperature. Four kinetic models have been employed to investigate adsorption mechanisms, and the experimental data more closely resemble a second-order process of the kinetic model. Adsorption studies on soil nanoclays have been shown to be highly effective in removing of Cu(II) from aqueous solution. This adsorbent is widely available as a natural material, is mechanically stable and, most importantly, it is environmentally appealing. The maximum Cu(II) adsorption capacity of soil nanoclays (31.7 mg/g) is more than three times higher than natural soil clays (10.2 mg/g). Our study demonstrates that soil nanoclays can be used effectively for removal of Cu(II) from aqueous systems to achieve environmental cleaning purposes. [ABSTRACT FROM AUTHOR]

Rainfall intensity and slope gradient are important factors that affect soil erosion; however, contradictory observations have been made due to different experimental conditions and materials. Colluvial deposits with loose, coarse material and steep slopes are easily erodible, but the erosion mechanism of colluvial deposition remains obscure. This work investigated the effects of heavy and storm rainfall intensity and steep slope gradients on the infiltration, runoff, and soil loss of colluvial soil. The rainfall intensity ranged from 1.00 to 2.33 mm min-1, and the slope gradient ranged from 36 to 84%. The infiltration rates declined sharply in the initial stage, whereas an opposite trend was observed for runoff rates until a steady state was reached after 5 min. Single- and multiple-peak models illustrated the two types of changes for the sediment yield process. The infiltration volume and the coefficient increased with increasing rainfall intensity and decreased with increasing slope, whereas the runoff coefficient decreased with increasing rainfall intensity and increased with increasing slope. Runoff volume and sediment yield increased with increasing rainfall intensity but had a critical slope gradient of 58% and >47%. The sediment concentration increased with increasing rainfall intensity, and first increased and then decreased with increasing slope gradients at rainfall intensities of 1.00 and 1.33 mm min-1 but increased at rainfall intensities of 1.67, 2.00, and 2.33 mm min-1. The findings of this study can be used to clarify the erosion mechanisms in disturbed soils with high coarse particle content. [ABSTRACT FROM AUTHOR]

Wine processing waste sludge (WPWS) has been shown to be an effective sorbent for sorption of nickel, lead, and chromium, but the sorption of copper (Cu) in aqueous solution by WPWS has not been conducted. The objective of this study was to explore the sorption mechanism of WPWS for copper. Infrared analysis revealed carboxyl was the major functional group in WPWS. The WPWS sorption isotherms of copper were only well described by Langmuir sorption isotherm. The maximum adsorption capacity (Qm) was 14.26 mg/g at 50 °C. A pseudo-second-order sorption kinetic model successfully described the kinetics of copper sorption onto WPWS. The Gibb free energies (&Dgr;G°) ranged from -20.69 to -24.29 kl mol-1, and the &Dgr;H° and &Dgr;S° were 5.048 kj mol-1 and 91.05 J mol-1 K-1, respectively. The trend of the intra-particular diffusion rate is the opposite of the adsorption constant of the pseudo-second-order equation. Water Environ. Res., 84, 733 (2012). [ABSTRACT FROM AUTHOR]

Dye wastewaters usually contain toxins and high chroma, making them difficult to treat with biological methods. The adsorption process plays an important role in removing dyes from wastewaters. This study aimed to explore the methylene blue (MB) adsorption mechanism by wine-processing waste sludge (WPWS). The WPWS contains a high cation-exchange capacity (64.2 cmolc kg-1) and organic matter (52.8%). The parameters affecting MB adsorption included pH, initial concentration of MB, reaction temperature, particle size and dosage of WPWS. The WPWS adsorption isotherms of MB were only well described by Langmuir adsorption isotherm. The maximum adsorption capacity (Qm) of MB was 285.7 mg g-1 at 25 °C. The activation energy determined by Arrhenius equation is 29.995 kJ mol-1. Under steady-state reaction conditions, the Gibb free energy (▵G°) ranged from -24.607 to -27.092 kJ mol-1 and ▵H° was -8.926 kJ mol-1, indicating that lower reaction temperature would favor MB adsorption. Therefore, MB adsorption by WPWS was a spontaneous, exothermic and physisorption reaction. [ABSTRACT FROM AUTHOR]

Information on the nature, physicochemical properties, and environmental fate of nanoparticles is severely lacking. Zeolite A was used to demonstrate its structural transformation from well crystalline to short-range-ordered (SRO) particles, including nanoparticles with size fractions in the range of 450 to 2000, 100 to 450, 25 to 100, and 1 to 25 nm. The chemical properties of a zeolite are dependent on its framework structure, which is formed by connecting truncated octahedra (sodalite) through the simple double four rings (D4-R) with external linkage in each sodalite. With decreasing particle size, the T(Si, Al)-O asymmetric and symmetric stretching vibrations shifted toward higher frequencies and the Si to Al molar ratio increased consistently from 1.8 to 5.2. The chemical shift of 27Al and 29Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra was related to its structural transformation from well crystalline to SRO particles, which was attributed to the loss of external linkage D4-R units in the structure. Comparing the various particle-size fractions (PSFs) showed significant differences in surface area, Si/Al molar ratio, morphology, crystallinity, framework structure, and surface atomic structure of nanoparticles from those of the bulk sample (i.e.,<2000 nm) before particle-size fractionations. Formation of these most reactive nanoparticles were caused by physicochemical weathering merits increasing attention with reference to their nature and properties, and their importance in ecosystem integrity. [ABSTRACT FROM AUTHOR]

Emulsion resins are widely used in wood-based materials for indoor furnishings. Previous studies have demonstrated that the ability of a material to retard flame arises from the interactions between four major components: i.e., binder resin (BR); carbonizing substrate (CS); foam-producing substance (FPS); and dehydrating agent (DA). Fire performance as influenced by wetting and drying cycle (WDC) treatment has not yet been reported. This study aimed to compare the fire performance of materials coated with EVAc (ethylene vinyl acetate copolymer) and PVAc (polyvinyl acetate copolymer) emulsion resins of differing BR/CS ratios, subjected to investigation by cone calorimeter. Intumescent formulation significantly enhanced the fire retardancy of painted plywood by exhibiting lower peak heat release rates (PHRR) and longer time to reach peak release rates. Additionally, lower BR content in the fire retardant systems further enhanced flame retardancy. The fire retardancy decreases with increasing the WDC treatment, caused by the weight loss of the coating materials. Infrared (FT-IR) analysis demonstrated that lower BR content extends the survival duration of the phosphorcarbonaceous structure of chars. The findings in this study enhance the state-of-the-art understanding of the effect of the intumescent. [ABSTRACT FROM AUTHOR]

Development of new and effective solid catalysts (solid acid base to immobilized enzyme) is necessary for renewable and green energy production. The various choices of heterogeneous solid catalysis were reported recently, and the specific research outcomes of trans-esterification on heterogeneous catalysis are discussed in the present article. The studies on biodiesel production are mainly focused on the following aspects: (i) examining the appropriate oil source, (ii) establishing the adequate alcohol to oil molar ratio, and (iii) evaluating the available solid acid catalysts, solid base catalysts, and lipase immobilized enzyme catalysts. Although homogeneous catalysis are superior in terms of reaction rate compared to heterogeneous catalysis, the focus of research on development of solid catalysts for heterogeneous catalytic transesterification is directed from the point of easy process and possible adoption for large scale production. The scope of this presentation is to examine these aspects in detail and to provide a comprehensive outlook on the aspects mentioned. [ABSTRACT FROM AUTHOR]

Abstract  Acrylic emulsion based painted red lauan plywood (Parashorea spp.) is most commonly used for indoor furnishings. This study investigated the enhancement of the fire retardance of painted plywood by interaction among four major components of intumescent formulation: (1) acrylic emulsion resin as binder resin (BR), (2) pentaerythritol as carbonizing substance (CS), (3) melamine as foam producing substance (FPS) and (4) ammonium polyphosphate as dehydrating agent (DA). Effects of changing BR/CS ratios (designated as FRA series) and FPS/DA ratios (designated as FRM series) on flame-retardance of painted plywood were investigated using a cone calorimeter. The intumescent formulation significantly enhanced fire retardancy of painted plywood by exhibiting lower peak release rates and longer times to reach peak release rates, compared with uncoated plywood (UP) panel and plywood panel solely coated with acrylic emulsion resin. Lower BR content in the FRA series and lower FPS content in the FRM series were shown to enhance flame retardancy of painted plywood. The positive correlation between total heat release values under increasing combustion duration and incremental changes of BR and FPS contents in two series further verified the above findings. Consistent with the observed flame retardancy enhancement of painted plywood, lower heats of combustion and weight losses for paints in the FRM series were also identified by oxygen bomb calorimeter measurements and thermogravimetrical analysis. Infrared analysis of the chars indicated the formation of phosphate ester linkages with the lowest BR content in the FRA series and the lowest FPS content in the FRM series showing superior enhancements of flame retardancy for painted red lauan plywood. [ABSTRACT FROM AUTHOR]

Low-molecular-weight organic acids (LMWOAs) derived from root exudates and complexed with available metals in the rhizosphere soils of Taiwan red cypress (Chamaeyparis formosensis, FRS), peacock pine (Cryptomeria japonica, JRS), and moso bamboo (Phyllostachys pubescens, PRS) were identified by gas chromatograph (GC). The fresh plants (i.e., leaves, stems, roots, and litters) and soil samples of those three vegetations were examined for their organic functional groups. This study focused on (1) assessing methods for processing LMWOAs in the rhizosphere soils and fresh plants by GC analysis and (2) determining the relative proportions of organic carbon (C) functional groups in the three vegetations and fresh plant materials with 13C nuclear magnetic resonance (NMR) analysis. The proportion of LMWOAs contents followed the order of PRS>FRS>JRS>bulk soils. The recovery and spiking tests analyzed by GC showed good recovery (>83.6%) and reproducibility of LMWOAs. The proportion of organic functional groups in the rhizosphere and bulk soil quantified by 13C NMR analysis followed the general order alkyl-C>aromatic-C>O-alkyl-C>N-alkyl-C>phenolic-C>acetal-C>carboxyl-C. The carbohydrates, hemicellulose, lignin, and cellulose contents obtained by 13C NMR analysis suggested that Phyllostachys pubescen (PB) cannot easily be decomposed under the mountain forest soil environments. [ABSTRACT FROM AUTHOR]

The objective of this study was to provide fundamental knowledge of arsenate sorption on lithium/aluminum layered double hydroxide intercalated by chloride (Li/Al LDH-Cl) and further to reveal the contribution of exposed positive charge surface of Li/Al LDH-Cl created by intercalating LiCI into Al(OH)3 layers to arsenate sorption. Therefore, sorption isotherms, envelopes and extended X-ray absorption fine structure (EXAFS) technique were employed to examine the reaction of arsenate on Li/Al LDH-CI and on gibbsite. Based on an isotherm study, the sorption maximum of Li/Al LDH-CI for arsenate was approximately six times higher than that of gibbsite. Sorption envelopes of arsenate on Li/Al LDH-Cl displayed a pH-sensitive behavior from pH 4.0 to 7.0, but it was insensitive to pH above pH 7.0, approaching to the PHpzc of Li/Al LDH-Cl (7.22). This transformation with shifted pHs illustrated that there were two types of reaction sites within Li/Al LDH-Cl that participate in arsenate sorption; one is pH-sensitive and the other is not. From EXAFS analysis, arsenate sorbed on Li/Al LDH, reacted not only with Al in the edges of Al-(OH)3 layers, but also with Li located in the vacant octahedral sites within Al(OH)3 layers; however, the decreasing intensity of As(V)-Al shells with increasing pH represented there were fewer As(V)-Al complex existed at higher pH, i.e., the complex between arsenate and Al is pH-sensitive. The superior sorption capability of Li/Al LDH-Cl to that of gibbsite could be attributed to the intercalated Li cations which served as the permanent sorption sites and made the surface of Al(OH)3 have high affinity to arsenate. [ABSTRACT FROM AUTHOR]

To recognize physiological response of plants to cadmium (Cd) toxicity in rhizosphere of plants, the pot experiments were employed to investigate how low-molecular-weight organic acids (LMWOAs) were exudated from tobacco and sunflower roots of Cd-amended soils. The aims of this study were to assess the effect of LMWOAs on uptake of Cd by tobacco and sunflower under pot experiments, thus comparing the ability of tobacco and sunflower for phytoremediation. Surface soils (0-20 cm) were collected from Taichung Experiment Station (TC) (silty loam). Cadmium chloride (CdCI2) was amended into TC soil, giving Cd concentrations of 1, 5, 10 mg kg-1 soil. Soils with different concentrations of Cd were put into 12 cm (i.d.) pots for incubation, and then 2-week-old tobacco and sunflower seedlings were transplanted into the pots. Tobacco and sunflower were grown in greenhouse for 50 days, respectively. The rhizosphere and bulk soils, and fresh plant tissues were collected after harvest. The Cd concentrations in the plant and transfer factor values in the sunflower were higher than that in the tobacco. No LMWOAs were detected by gas chromatograph in bulk soils, and low amounts of LMWOAs were found in uncontaminated rhizosphere soils. Acetic, lactic, glycolic, malic, maleic, and succinic acids were found in the tobacco and sunflower rhizosphere soils. Concentrations of LMWOA5 increased with increasing amendment of Cd concentrations in tobacco and sunflower rhizosphere soils. Correlation coefficient (r) of concentrations of Cd amendment versus LMWOA5 exudates of tobacco and sunflower were 0.85 and 0.98, respectively. These results suggest that the different levels of LMWOAs present in the rhizosphere soil play an important role in the solubilization of Cd that bound with soil particle into soil solution and then uptake by plants. [ABSTRACT FROM AUTHOR]

The organoclays Wyoming montmorillonite (SWy‐1, Mon), W. R. Grace vermiculite (Ver), and Tung‐Wei (Tw) soil montmorillonite were prepared to sorb or remove chlorophenoxy propionic acids (CPA) pollutants such as 2,4‐dichlorophenoxy acid (2,4‐DP), 2,4,6‐tri chlorophenoxy acid (2,4,6‐TCP), and pentachlorophenoxy propionic acid (PCP). The objective of this study was to evaluate the behavior of organoclays that have sorbed three types of CPA and to assess the applicability to basaltic‐developed iron‐rich calcareous soil. This type of soil contains high amounts of montmorillonite. The mean‐layer charge per formula unit of Mon, Ver, and Tw clays, characterized by the alkylammonium method, was 0.27, 0.70, and 0.52 mol(c)/O10(OH)2, respectively. The sorption isotherms of 2,4‐DP, 2,4,6‐TCP, and PCP sorbed by hexadecyltrimethyl‐ammonium (HDTMA organoclay, 150% cation‐exchange capacity) were evaluated. The data on sorption of CPAs fit well with the Freundlich isotherm equation. In general, the sorption of three types of CPA by the organoclays showed a linear relationship, with a high correlation coefficient (r > 0.935). The Kf value of PCP was the same as that of 2,4,6‐TCP sorbed by the organoclays and was higher than that of 2,4‐DP. However, the 1/nf values of the three CPAs sorbed by the organoclays did not show significant differences. In general, maximum CPA sorption occurred at a pH of approximately 3, but very significant differences were observed for the 2,4,6‐TCP and PCP sorbed by the organoclays. However, there was no significant difference in pH for 2,4‐DP sorption. This should be related to the solubility and pKa of each CPA. The experimental results showed that solubility of 2,4‐DP, 2,4,6‐TCP, and PCP is a function of pH, ionic strength, and temperature. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 71–79, 2006. [ABSTRACT FROM AUTHOR]

The objectives of this study were to investigate selected physical and chemical properties, and availability of metals in rhizosphere and bulk soils of Tsuga and Yushania of alpine forests. The pH of rhizosphere soils was lower than bulk soils. Mean CEC, organic carbon, carbon/nitrogen (C/N) ratio, and clay contents in rhizosphere soils were greater than in bulk soils (P < 0.05). Concentrations of exchangeable potassium (K) and magnesium (Mg) were also greater in rhizosphere soils than in bulk soils. The availability of aluminum (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in rhizospheres was influenced by the ionic species and concentrations, which depend on the pH change and chemical compositions of root exudates. [ABSTRACT FROM AUTHOR]

Discusses the determination of low molecular weight dicarboxylic acids and organic functional groups in rhizosphere and bulk soils of Tsuga and Yushania in a temperate rain forest.

The blue-tailed bee-eater ( Merops philippinus) is a summer migrant that breeds on Kinmen Island, located off the west coast of Taiwan, about 5 km from the southern coast of mainland China. The aim of this study was to investigate why blue-tailed bee-eaters build their nests in sandy loam and sandy clay loam, but not in clay loam. Soil chemical and physical properties, and mineralogical composition were measured for the different soil types. Clay loam had a significantly lower pH, Na, and base saturation than did sandy loam or sandy clay loam. Clay loam had a significantly higher N, cation-exchange capacity (CEC), K, and free iron (Fed) and aluminum oxide (Ald) contents than the other soil types. Clay loam had significantly lower sand and higher clay content, and higher bulk density and penetration resistance than the other soil types. The correlation coefficients ( r 2) between penetration resistance and Fed, Ald, and clay contents were 0.997, 0.848, and 0.779, respectively. Soil strength and compaction are important criteria for bee-eaters’ nesting-site selection. The lower pH of clay loam would enhance the exchangeable Al and acidity, further increasing the soil aggregation. Thus, it might prevent the bee-eaters from excavating nesting burrows. [ABSTRACT FROM AUTHOR]

The most prominent paleosol unit in the Chinese Loess Plateau (CLP) is the fifth paleosol complex (S5) with its well-developed very thick and dark colored pedons. To provide more insight in the formation of S5 and its environmental significance, the pedogenesis and clay mineral transformation in the S5 of the Wugong section (Shaanxi Province) on the southernmost CLP are analyzed. S5 at the Wugong section is essentially composed of three well-developed reddish pedons (i.e., S5 -1, S5 -2, S5 -3) which signify three glacial-interglacial climatic fluctuations during its formation. Complete decalcification in each pedon and a calcic horizon of only 30-50 cm in thickness beneath each of the three pedons suggests that after deposition the pedons developed with a relatively stable surface in a sustained warm and humid climate. Clay formation in the S5 includes neogenesis of clay materials by in situ post-depositional weathering and mechanical migration of the fine fraction after complete decalcification. Complete leaching of CaCO3, intensive clay formation (with 60-100% higher clay content than that in the overlying and underlying loess (L5 and L6)) and extremely high magnetic susceptibility in the S5 pedons reflected a warmer, more humid climate and soil environment for pedogenesis than in the 'optimum' Holocene. However, the chemical alteration of the phyllosilicate minerals was weak and restrained by the hard calcic horizon, the compact argillic horizon and the flat terrain. The major clay mineral weathering processes during the formation of the S5 pedons at the Wugong section were depotassication, hydrolysis of primary minerals and degradation of chlorite. The pedogenesis in a loess-paleosol sequence and its pedogenic environment can best be deduced from combined data on pedogenic properties, and geochemical and mineralogical characteristics. [ABSTRACT FROM AUTHOR]

Ammonia oxidization is a critical step in the soil N cycle and can be affected by the fertilization regimes. Chinese milkvetch (Astragalus sinicus L., MV) is a major green manure of rice (Oryza sativa L.) fields in southern China, which is recommended as an important agronomic practice to improve soil fertility. Soil chemical properties, abundance and community structures of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in a MV-rice rotation field under different fertilization regimes were investigated. The field experiment included six treatments: control, without MV and chemical fertilizer (CK); 100% chemical fertilizer (NPK); 18 000 kg MV ha-1 plus 100% chemical fertilizer (NPKM1); 18 000 kg MV ha-1 plus 40% chemical fertilizer (NPKM2); 18 000 kg MV ha-1 alone (MV); and 18 000 kg MV ha-1 plus 40% chemical fertilizer plus straw (NPKMS). Results showed that NPKMS treatment could improve the soil fertility greatly although the application of 60% chemical fertilizer. The abundance of AOB only in the MV treatment had significant difference with the control; AOA were more abundant than AOB in all corresponding treatments. The NPKMS treatment had the highest AOA abundance (1.19 × 108 amoA gene copies g-1) and the lowest abundance was recorded in the CK treatment (3.21 × 107 amoA gene copies g-1). The abundance of AOA was significantly positively related to total N, available N, NH4+-N, and NO3--N. The community structure of AOA exhibited little variation among different fertilization regimes, whereas the community structure of AOB was highly responsive. Phylogenetic analysis showed that all AOB sequences were affiliated with Nitrosospira or Nitrosomonas and all AOA denaturing gradient gel electrophoresis (DGGE) bands belonged to the soil and sediment lineage. These findings could be fundamental to improve our understanding of AOB and AOA in the N cycle in the paddy soil. [ABSTRACT FROM AUTHOR]

The soil carbon reservoir is the largest carbon reservoir in terrestrial ecosystems and consists of soil organic and inorganic carbon stocks. Previous studies have mainly focused on the soil organic carbon (SOC) stock, and limited information is available about the soil inorganic carbon (SIC) stock. The Chinese Loess Plateau (CLP), which is located in the arid and semi-arid region of China, is an important inorganic carbon reservoir, with a thick soil layer that is rich in calcium carbonate. However, there are few reports on the SIC stock and its spatial distribution in this region. In the current study, the SIC densities and stocks for various soil types and land use patterns were evaluated based on 495 profiles with 2470 soil samples across the CLP, which were collected from the Chinese Second National Soil Survey. The results showed that in the top 1m of soil across the CLP, the average SIC density is 17.04kg/m², and the total SIC stock is approximately 10.20 Pg C (1 Pg=1015g). The SIC stock of the CLP accounts for approximately 18.4% of the total SIC stock throughout China. The average values of the SIC stock in the 0-20, 20-50 and 50-100cm depths of the CLP are 2.39, 2.92 and 4.89 Pg, respectively. Under different land use patterns, the order of the average SIC density is farmland≈grassland > forest in all soil layers. For the various soil types, the SIC density in the 0-100cm layer is the highest in alkaline soil and lowest in subalpine meadow soil, whereas the SIC stock is highest in loessial soil, eolian sandy soil and sierozem, and the lowest in subalpine meadow soil. These differences are largely a result of the area occupied by each soil type and the climate conditions. The results of this study provide basic information about carbon reservoir in China and contribute to our understanding of the SIC stock on the CLP as it relates to the carbon balance of terrestrial ecosystems. [ABSTRACT FROM AUTHOR]