Characterization of fluvo-aquic soil phosphorus affected by long-term fertilization using solution 31P NMR spectroscopy.

Reducing the applications of mineral phosphorus (P) fertilizers and supplementing them by organic fertilizers is becoming a necessary practice in the North China Plain due to overuse of mineral P fertilizers and improper disposal of organic wastes. Knowledge is needed about how the long-term substitution of mineral fertilizers by organic fertilizers affects soil P forms in order to understand soil P transformation and crop P uptake. In this study, we used solution 31P nuclear magnetic resonance (NMR) spectroscopy to characterize P forms in fluvo-aquic soil after 26 years of different fertilization management strategies, organic compost (OM), half compost in combination with half mineral fertilizer NPK (1/2 OM), mineral fertilizer NPK (NPK), mineral fertilizer NK (NK), and an unfertilized control (CK). Results showed that the P extraction efficiency using NaOH-EDTA varied from 13.0 to 27.7% for the soils of the treatments. 31P NMR spectra indicated that the majority of P was in the form of orthophosphate for all the treatments, which constituted 64.3-83.5% of the total extracted P. The application of P fertilizers significantly increased the concentrations of orthophosphate, monoesters and diesters regardless of the P fertilization method, although the proportions of monoesters and diesters were higher in CK. The proportions and concentrations of orthophosphate significantly decreased when all mineral fertilizers were replaced by compost. There was no significant difference in the proportions and concentrations of total organic P, corrected monoesters and diesters in NaOH-EDTA extracts of soils among NPK, 1/2OM and OM treatments. Decreasing mineral P fertilizers and partly replacing them by organic fertilizer in fluvo-aquic soil might increase soil test (Olsen) P and crop P uptake through the degradation of applied organic P forms.

Hydrothermal preparation and characterization of novel corncob-derived solid acid catalysts.

Novel corncob-derived solid acid catalysts were successfully synthesized for the first time by the hydrothermal method. The influences of different preparation conditions were investigated, and the structure-function relationships of the resulting catalysts were also discussed on the basis of the analysis of structure and composition. In comparison to conventional solid acid catalysts, the corncob-derived catalyst synthesized under optimized conditions exhibited higher catalytic activity in esterification reactions, yielding nearly 90% methyl oleate in only 2 h. The catalyst retained satisfactory catalytic activity for esterification, even after 8 reaction cycles. Solid-state magic angle spinning (MAS) (13)C nuclear magnetic resonance (NMR) investigations further indicated that the catalyst was composed of polycyclic aromatic carbon sheets bearing -SO3H, -COOH, and -OH groups in adequate amounts and with proper proportions, contributing to its excellent catalytic activity. This work provides a green method to synthesize solid acid catalysts from biomass wastes and may contribute to a holistic approach for biomass conversion.

Localization of fluoride and aluminum in subcellular fractions of tea leaves and roots.

The tea plant is a fluoride (F) and aluminum (Al) hyperaccumulator. High concentrations of F and Al have always been found in tea leaves without symptoms of toxicity, which may be related to the special localization of F and Al in tea leaves. In this study, we for the first time determined the subcellular localization of F and Al in tea roots and leaves and provided evidence of the detoxification mechanisms of high concentrations of F and Al in tea plants. Results revealed that 52.3 and 71.8% of the total F accumulated in the soluble fraction of tea roots and leaves, and vacuoles contained 98.1% of the total F measured in the protoplasts of tea leaves. Cell walls contained 69.8 and 75.2% of the total Al detected in the tea roots and leaves, respectively, and 73.2% of Al sequestered in cell walls was immobilized by pectin and hemicellulose components. Meanwhile, 88.3% of the Al measured in protoplasts was stored in the vacuoles of tea leaves. Our results suggested that the subcellular distributions of F and Al in tea plants play two important roles in the detoxification of F and Al toxicities. First, most of the F and Al was sequestered in the vacuole fractions in tea leaves, which could reduce their toxicities to organelles. Second, Al can be immobilized in the pectin and hemicellulose components of cell walls, which could suppress the uptake of Al by tea roots.

Effects of biomass types and carbonization conditions on the chemical characteristics of hydrochars.

Effects of biomass types (bark mulch versus sugar beet pulp) and carbonization processing conditions (temperature, residence time, and phase of reaction medium) on the chemical characteristics of hydrochars were examined by elemental analysis, solid-state ¹³C NMR, and chemical and biochemical oxygen demand measurements. Bark hydrochars were more aromatic than sugar beet hydrochars produced under the same processing conditions. The presence of lignin in bark led to a much lower biochemical oxygen demand (BOD) of bark than sugar beet and increasing trends of BOD after carbonization. Compared with those prepared at 200 °C, 250 °C hydrochars were more aromatic and depleted of carbohydrates. Longer residence time (20 versus 3 h) at 250 °C resulted in the enrichment of nonprotonated aromatic carbons. Both bark and sugar beet pulp underwent deeper carbonization during water hydrothermal carbonization than during steam hydrothermal carbonization (200 °C, 3 h) in terms of more abundant aromatic C but less carbohydrate C in water hydrochars.

Chemical structure and heterogeneity differences of two lignins from loblolly pine as investigated by advanced solid-state NMR spectroscopy.

Advanced solid-state NMR was employed to investigate differences in chemical structure and heterogeneity between milled wood lignin (MWL) and residual enzyme lignin (REL). Wiley and conventional milled woods were also studied. The advanced NMR techniques included 13C quantitative direct polarization, various spectral-editing techniques, and two-dimensional 1H-13C heteronuclear correlation NMR with 1H spin diffusion. The 13C chemical shift regions between 110 and 160 ppm of two lignins were quite similar to those of two milled woods. REL contained much more residual carbohydrates than MWL, showing that MWL extraction more successfully separated lignin from cellulose and hemicelluloses than REL extraction; REL was also of higher COO, aromatic C-C, and condensed aromatics but of lower aromatic C-H. At a spin diffusion time of 0.55 ms, the magnetization was equilibrated through the whole structure of MWL lignin, but not through that of REL, indicating that REL is more heterogeneous than MWL.

Chemical structures of manure from conventional and phytase transgenic pigs investigated by advanced solid-state NMR spectroscopy.

Nonpoint phosphorus (P) pollution from animal manure is becoming a serious global problem. The current solution for the swine industry includes the enzyme phytase as a component in oil meal and cereal grain-based swine diets. A long-term approach is the production of transgenic phytase pigs that express phytase in the salivary glands and secrete it in the saliva. This study provides a detailed comparison of chemical structures of manure from conventional pigs and transgenic pigs that express phytase under growing and finishing phases using new solid-state NMR techniques. Spectral editing techniques and quantitative NMR techniques were used to identify and quantify specific functional groups. Two-dimensional (1)H- (13)C heteronuclear correlation NMR was used to detect their connectivity. Manure from conventional and transgenic pigs had similar peptide, carbohydrate, and fatty acid components, while those from transgenic pigs contained more carbohydrates and fewer nonpolar alkyls. There was no consistent effect from diets with or without supplemental phosphate or growth stages.