基于Illumina MiSeq测序平台分析长期不同施肥处理对黑土真菌群落的影响

【目的】不合理施肥所引发的土壤环境问题逐渐成为制约我国农业可持续发展的重要因素之一,土壤真菌作为一类重要的土壤微生物,研究长期施肥对土壤真菌多样性及群落分布格局,探讨其理化因子对真菌群落结构的影响具有一定意义。【方法】本研究以东北黑土玉米田长期定位施肥试验(1984–2017)为基础,通过常规分析和Illumina Mi Seq高通量测序技术,分析长期施肥对黑土玉米田土壤养分含量和真菌群落结构变化的影响。【结果】长期施用氮肥明显降低土壤p H,却增加了玉米产量,秸秆与化肥配施可以增加土壤有机质和全氮的含量。稀释曲线结果表明长期施肥降低了土壤真菌序列的丰度和均匀度,并且在秸秆与化肥配施中序列数最低;在优势菌群中,共检测出5个已知真菌门,分别是子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、接合菌门(Zygomycota)、球囊菌门(Glomeromycota)和壶菌门(Chytridiomycota),子囊菌门占总序列平均值的57.0%,并且在氮磷钾配施高量秸秆有机肥(NPK+S0.5)的土壤中,子囊菌门丰度高达70.35%。在土壤真菌属水平的物种丰度分析中,共检测出109个已知真菌属,Humicola、Fusarium、Verticillium、Mortierella这4个菌属为优势菌属;Chaetomium、Trichocladium、Podospora、Preussia 4个菌属在秸秆与化肥配施处理中丰度较高,并同属一个分支聚类。从多样性指数分析得出,秸秆与化肥配施可以增加物种丰度和群落多样性;从热图分析可知,施用氮肥和不施用氮肥处理间真菌群落组成存在明显差异。RDA分析中,土壤理化性质影响着土壤真菌群落结构,尤其是土壤的p H、全量氮磷钾(T-N、T-P、T-K)、有效磷钾(A-P、A-K)和铵态氮(NH4+-N)浓度是重要环境因素。【结论】因此,施用氮肥虽然增加了产量,但也造成土壤酸化,真菌数量增加,其丰富度和多样性明显降低。而秸秆与化肥配施可以维持土壤健康生态环境和真菌群落多样性。

Fabrication of highly efficient Bi2WO6/CuS composite for visible-light photocatalytic removal of organic pollutants and Cr(VI)from wastewater

A visible-light-driven Bi_(2)WO_(6)/CuS p-n heterojunction was fabricated using an easy solvothermal method.The Bi_(2)WO_(6)/CuS exhibited high photocatalytic activity in a mixed system containing rhodamine B(RhB),tetracycline hydrochloride(TCH),and Cr(VI)under natural conditions.Approximately 98.8%of the RhB(10 mg/L),87.6%of the TCH(10 mg/L)and 95.1%of the Cr(VI)(15 mg/L)were simultaneously removed from a mixed solution within 105 min.The removal efficiencies of TCH and Cr(VI)increased by 12.9%and 20.4%,respectively,in the mixed solution,compared with the single solutions.This is mainly ascribed to the simultaneous consumption electrons and holes,which increases the amount of excited electrons/holes and enhances the separation efficiency of photogenerated electrons and holes.Bi_(2)WO_(6)/CuS can be applied over a wide pH range(2–6)with strong photocatalytic activity for RhB,TCH and Cr(VI).Coexisiting dissolved organic matter in the solution significantly promoted the removal of TCH(from 74.7%to 87.2%)and Cr(VI)(from 75.7%to 99.9%)because it accelerated the separation of electrons and holes by consuming holes as an electron acceptor.Removal mechanisms of RhB,TCH,and Cr(VI)were proposed,Bi_(2)WO_(6)/CuS was formed into a p-n heterojunction to efficiently separate and transfer photoelectrons and holes so as to drive photocatalytic reactions.Specifically,when reducing pollutants(e.g.,TCH)and oxidizing pollutants(e.g.,Cr(VI))coexist in wastewater,the p-n heterojunction in Bi_(2)WO_(6)/CuS acts as a“bridge”to shorten the electron transport and thus simultaneously increase the removal efficiencies of both types of pollutants.

Experimental and theoretical study of microwave enhanced catalytic hydrodesulfurization of thiophene in a continuous-flow reactor

Hydrodesulfiirization(HDS)of thiophene,as a gasoline model oil,over an industrial Ni-Mo/Al2O3 catalyst was investigated in a continuous system under microwave irradiation.The HDS efficiency was much higher(5%-14%)under microwave irradiation than conventional heating.It was proved that the reaction was enhanced by both microwave thermal and non-thermal effects.Microwave selective heating caused hot spots inside the catalyst,thus improved the reaction rate.From the analysis of the non-thermal effect,the molecular collisions were significantly increased under microwave irradiation.However,instead of being reduced,the apparent activation energy increased.This may be due to the microwave treatment hindering the adsorption though upright S-bind(η1)and enhancing the parallel adsorption(η5),both adsorptions were considered to favor to the direct desulfurization route and the hydrogenation route respectively.Therefore,the HDS process was considered to proceed along the hydrogenation route under microwave irradiation.

Capture condition for endo-atmospheric interceptors steered by ALCS and ARCS

This contribution deals with capture condition for interceptor missiles steered by aero-lift control system （ALCS） and attitude reaction-jet control system （ARCS）. With the guidance law derived from bounded differential game formulation, existence condition of capture zone is studied for the case that the interceptor has advantage on maneuverability and disadvantage on agility. For the existence of the open capture zone, ARCS can only close after the engagement terminates. Moreover, ARCS also needs to contribute to maneuverability over the minimum required value. More fuel will be required if ARCS increases its contribution to maneuverability. The minimum required fuel occurs at the tangent point of two curves： the curve of critical parameters and a candidate constraint curve, which is also true even for the complex propellant constrain. The validity of these results is also demonstrated by simulations.

Amplification of Flood Risks by the Compound Effects of Precipitation and Storm Tides Under the Nonstationary Scenario in the Coastal City of Haikou,China

In the context of climate change,coastal cities are at increased risk of extreme precipitation and sea level rise,and their interaction will aggravate coastal floods.Understanding the potential change of compound floods is valuable for flood risk reduction.In this study,an integrated approach coupling the hydrological model and copulabased design of precipitation and storm tides was proposed to assess the compound flood risk in a coastal city—Haikou,China.The copula model,most-likely weight function,and varying parameter distribution were used to obtain the combined design values of precipitation and storm tides under the nonstationary scenario,which were applied to the boundary conditions of the 1D-2D hydrological model.Subsequently,the change of the bivariate return periods,design values,and compound flood risks of precipitation and storm tides were investigated.The results show that the bivariate return period of precipitation and storm tides was reduced by an average of 34%under the nonstationary scenario.The maximum inundation areas and volumes were increased by an average of 31.1%and 45.9%respectively in comparison with the stationary scenario.Furthermore,we identified that the compound effects of precipitation and storm tides would have a greater influence on the flood risk when the bivariate return period is more than 50 years,and the peak time lag had a significant influence on the compound flood risk.The proposed framework is effective in the evaluation and prediction of flood risk in coastal cities,and the results provide some guidance for urban disaster prevention and mitigation.