Distribution of phosphorus forms in surface soils of typical peatlands in northern Great Khingan Mountains and its potential to reconstruct paleo-vegetations.

Phosphorus was one of the nutrient limitations to vegetations in wetland ecosystem. In peatland, organic phosphorus is accumulated as vegetation residues in anaerobic conditions, affecting the contents of phosphorus pools for long time. It is unclear that different vegetations affect the contents of phosphorus and whether successions of vegetations could reflected by sedimentation of phosphorus forms. Phosphorus forms from six surface soils plots and four dominant vegetations in the north of the Great Khingan mountains were detected to investigate the differences of phosphorus forms of soil between different vegetations. Phosphorus forms and macrofossil were also detected in a 77-cm peat core (1-cm intervals) in TQ. A fingerprinting historical vegetations were reconstructed by phosphors forms to reflect successions of vegetations during 2200 cal yr BP in TQ area. The results showed that the main phosphorus forms in peatland were NaOH-Po and conc. HCl-Po. The percentages of inorganic phosphorus forms of trees were generally higher than other vegetations. Moss was more conducive for accumulation of organic phosphorus. NaHCO3-Pi, NaOH-Pi, conc. HCl-Po and Pi were selected into linear discrimination analysis. The vegetations reconstructed by phosphorus forms were strongly correlated with the pollen records of moss, herbs and shrubs, as well as with macrofossils in herbs. The fingerprinting of vegetations by phosphorus has potential geochemical reference to reflect the successions of vegetation in peatland.

The inhibitory effects of sesamol and sesamolin on the glycidyl esters formation during deodorization of vegetables oils.

BACKGROUND: Glycidyl esters (GEs) have attracted worldwide attention for their potential harm to human health. The GEs in edible oils mainly form during the deodorization of the oil refining processes. We used sesamol and sesamolin to inhibit the formation of GEs in model corn oil (MCO), model palm oil (MPO) and model rice bran oil (MRO) during a deodorization process. RESULTS: The results showed that, in the three model oils, the total GE content was in the following order from highest to lowest: MRO (1437.98 µg kg-1 ) > MPO (388.64 µg kg-1 ) > MCO (314.81 µg kg-1 ). The inhibitory effect of the three antioxidants on the formation of GEs in the MCO was in the following order from strongest to weakest: tert-butylhydroquinone (TBHQ) > sesamol > sesamolin. CONCLUSION: When the mass percentage of sesamol was 0.05%, its inhibition percentage on GEs was close to the inhibition percentage of 0.02% added TBHQ. The present study provides a foundation for understanding how to inhibit the formation of GEs in oils by adding sesamol during the deodorization process.

Potential in paleoclimate reconstruction of modern pollen assemblages from natural and human-induced vegetation along the Heilongjiang River basin, NE China.

The relationships among modern pollen, vegetation, climate and human activities can help improving the reliability of reconstruction of past vegetation, regional climate and human activities based on fossil pollen records. We used a dataset of 114 surface soil pollen samples from natural vegetation (wetlands, forests and grasslands) and human-induced vegetation (farmlands and residences) along the Heilongjiang River basin in northeast China to explore the relationships among modern pollen, vegetation, climate and human activities. The results indicated that surface pollen assemblages differentiated modern vegetation well in natural and human-induced vegetation types. The wetlands were mainly composed of Cyperaceae, along with Artemisia, weeds Poaceae (<35 µm) and Sanguisorba. The forests were predominated by Pinus and Betula. Artemisia, weeds Poaceae (<35 µm) and Chenopodiaceae were the most important pollen taxa in grasslands. The farmlands were characterized by Artemisia, Aster, Chenopodiaceae, cereal Poaceae (>35 µm) and Taraxacum. The pollen assemblages of residences were composed of weeds Poaceae (<35 µm), Chenopodiaceae and Salix. Ordination analyses based on main pollen taxa and climatic variables were used to determine the relationships between pollen and climate, suggesting the surface pollen assemblages were primarily influenced by the mean annual temperature (Tann) in northeast China. The statistical performance of transfer function between pollen and Tann were well indicating the modern pollen assemblages could be reliably used in paleoclimate reconstruction in our study area. Furthermore, human-induced vegetation had high frequencies of human-companion pollen taxa, such as Chenopodiaceae, Aster, Taraxacum and cereal Poaceae (>35 µm). Pollen concentrations of human-induced vegetation were lower than natural vegetation types, which could be used as an indicator of human influence intensity.

Bionic radical generation and antioxidant capacity sensing with photocatalytic graphene oxide-titanium dioxide composites under visible light.

OH radicals as reactive oxygen species in an organism were applied to assay antioxidant capacity since the obtained results present high biological relevance. As a proper photocatalyst, titanium dioxide was employed to generate OH radicals under ultraviolet light irradiation. However, ultraviolet light can damage molecular probe (DNA or protein) during the detection of antioxidant capacity, which interferes with the results. In this article, a novel composite graphene oxide-titanium dioxide (GO-TiO2) nanostructure was synthesized, which can generate numerous OH radicals just under visible light irradiation. In addition, a novel electrochemical antioxidant capacity sensor was designed with GO-TiO2 composites as source of OH radicals and DNA as a molecular probe. Antioxidants were measured by using the suppression of the decline of reduction current of methylene blue used as an intercalating agent for DNA after irradiation and ˙OH-mediated DNA damage. Using gallic acid (GA) as a mode antioxidant species, the detection of GA at levels as low as 0.85 mg L(-1) was possible. The antioxidant capacity of other antioxidants was also assayed. Finally, the novel sensor was applied to the determination of antioxidant capacity in tea.