Characteristics of different aged plantations of Ormosia hosiei with regards to soil microbial biomass and enzymatic activities

Stand age is an important indicator of tree growth and life cycle,and has implications for ecological and biological processes.This study examined changes in soil microbial biomass(SMB)as well as enzyme activities of different aged plantations and revealed their relationship to soil properties.SMB,microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),microbial biomass phos-phorous(MBP)and enzyme activities(β-1,4-glucosidase(β-G),β-1,4-xylosidase(β-X),cellobiohydrolase(CBH),leucine aminopeptidase(LAP),β-1,4-n-acetylglucosamine(NAG)and acid phosphatase(ACP))were measured in Oro-mosia hosiei plantations of different ages.The soil qual-ity index(SQI)model assessed soil quality.SMB contents significantly decreased in young(7-year-old)and mature plantations(45-year-old)compared to middle-aged(20-year-old)plantations.Activity of soilβ-G,β-X,CBH and NAG in the 20-year-old plantations was markedly higher than in the other plantations except forβ-G,CBH and NAG in the 45-year-old plantations.Soil organic carbon(SOC),total potassium(TK),total porosity,dissolved organic carbon,nitrate nitrogen(NO_(3)--N)and non-capillary porosity were key factors affecting SMB,while soil bulk density,pH,SOC,NO_(3)--N,TK and forest litter(FL)were the main factors affecting soil enzyme activities.SQI decreased in the order:middle-aged>mature>young.The efficiency of soil organic matter conversion,the effect of nitrogen min-eralization and fixation by microorganisms,and the better efficiency of phosphorus utilization in mid-age plantations,which improves soil physical properties,better facilitates tree growth,and further improves the buffering of the soil against acidity and alkalinity.FL quality was the only soil biological factor affecting soil enzyme activity.Our findings demonstrate that different aged plantations affect soil micro-bial biomass,enzyme activity,and soil quality.

Factors affecting photocatalytic performance through the evolution of the properties due to the phase transition from NaBiO_(3)·2H_(2)O to BiO_(2−x)

The phase transition process of a photocatalytic system from NaBiO_(3)·2H_(2)O to BiO_(2−x) has been investigated to understand the important factors that affect photocatalytic performance in a composite system. It is found that a proper amount of BiO2−x on the surface of NaBiO_(3)·2H_(2)O could effectively suppress the electron/hole recombination and increase the exposed reactive sites for photocatalytic reaction. A fully covered BiO2−x on NaBiO3·2H2O results in a dramatical decrease of photocatalytic degradation of dye. An over long hydrothermal process can result in BiO_(2−x) with reduced oxygen vacancies, which degrades the photocatalytic activity. Furthermore, the photocatalytic reduction ability of CO_(2) conversion has been investigated, indicating that the surface activity to different reactants also directly affects the catalytic performance. The investigation of the gradient phase transition process presents a clear guidance to construct a desired photocatalytic system, in addition to selecting gradient materials with suitable bandgap structure and a morphology with different fraction and distribution of each component. The defect evolution of each component during construction of a composite is also an important factor that should be optimized and considered in making a composite to achieve high photocatalytic efficiency.

A mini-review of ferrites-based photocatalyst on application of hydrogen production

Photocatalytic water splitting for hydrogen production is a promising strategy to produce renewable energy and decrease production cost.Spinel-ferrites are potential photocatalysts in photocatalytic reaction system due to their room temperature magnetization,the high thermal and chemical stability,narrow bandgap with broader visible light absorption,and proper conduction band energy level with strong oxidation activity for water or organic compounds.However,the fast recombination of the photoexcited electrons and holes is a critical drawback of ferrites.Therefore,the features of crystallinity,particle size,specific surface area,morphology,and band energy structure have been summarized and investigated to solve this issue.Moreover,composites construction with ferrites and the popular support of TiO_(2)or g-C_(3)N_(4)are also summarized to illustrate the advanced improvement in photocatalytic hydrogen production.It has been shown that ferrites could induce the formation of metal ions impurity energy levels in TiO_(2),and the strong oxidation activity of ferrites could accelerate the oxidation reaction kinetics in both TiO_(2)/ferrites and g-C_(3)N_(4)/ferrites systems.Furthermore,two representative reports of CaFe2O4/MgFe2O4 composite and ZnFe2O4/CdS composite are used to show the efficient heterojunction in a ferrite/ferrite composite and the ability of resistance to photo-corrosion,respectively.