高等农业院校无机化学教学中绿色创新思维的培养探讨

注重培养学生的绿色创新思维是当今国际人才教育发展的大趋势。该文针对目前农业院校无机化学教育体系中存在的一些问题,并结合高等农业院校所具有的独特优势,提出了在无机化学教学中注入绿色创新思维培养,并对培养的具体方法和途径进行了探讨,进而激发大学生们对无机化学学习的热情和兴趣。     

Effects of Salinity,Commercial Salts,and Water Type on Cultivation of the Cryptophyte Microalgae Rhodomonas salina and the Calanoid Copepod Acartia tonsa

Marine aquaculture facilities positioned far from the sea need access to seawater (SW); hence, commercial salts are often the chosen solution. In marine hatcheries, most fish larvae require live feed (zooplankton) that are in turn fed with microalgae. The objective of this research was to investigate the applicability of commercial salts and clarify the potential effects on the cultivation of the microalga Rhodomonas salina and the copepod Acartia tonsa. Three commercial salts were tested, Red Sea Salt (RS), Red Sea – Coral Pro Salt (CP), and Blue Treasure Salt. R. salina was cultured at salinities of 10, 20, and 30 psu resulting in equal growth rates at salinities 20 and 30 in SW and RS mixed with deionized (DI) water. The optimum salinity for R. salina was 29 psu. For A. tonsa eggs, we observed highest hatching success in 30 psu with CP or RS mixed with DI water. The egg hatching success was not affected by salinities 15–40 and optimal hatching was obtained at 27 psu. Results confirm it was possible to use commercial salts for rearing of both R. salina and A. tonsa, widening the application of these species for aquaculture facilities without access to SW.     

MS培养基中氮、磷无机盐对鳗草克隆幼苗生存的影响

为了探究MS培养基中氮、磷无机营养盐对鳗草生长的影响。单独添加不同浓度KNO₃、NH₄NO₃和KH₂PO₄的天然海水中培养鳗草克隆苗,于7、14天进行植株形态学观察和叶片叶绿素含量测定。其中,KNO₃的添加量为MS培养基中的1/2倍、1倍和2倍及NO₃^-总浓度为39.4 mmol/L,KH₂PO₄和NH₄NO₃的添加量均为MS培养基中各自浓度的1/2、1和2倍。结果表明,叶绿素含量以KNO₃处理组最高(P<0.05),克隆苗培养14天无毒害现象,且有新叶发出;NH₄NO₃和KH₂PO₄处理组均对克隆苗有明显毒害作用,NH₄NO₃处理组叶片48 h后开始褐化,7天后茎尖、根尖明显变软并褐化,14天后植株死亡;KH₂PO₄处理组培养14天后叶片平均褐化率达56%。因此,1/2、MS培养基均不适用于鳗草的室内培养,其培养基的氮源应为单独添加的NO₃^--N或高浓度NO₃^--N+低浓度NH₄⁺-N。     

Population size and specific potential of P-mineralizing and -solubilizing bacteria under long-term P-deficiency fertilization in a sandy loam soil

The effects of organic manure, mineral fertilizer (NPK), and P-deficiency fertilization (NK) on the individual biomass of young wheat plants, arbuscular mycorrhizal (AM) colonization in wheat root systems, population sizes of soil organic phosphorus mineralizing bacteria (OPMB) and inorganic phosphate solubilizing bacteria (IPSB) as well as soil P-mineralization and -solubilization potential were investigated in a long-term (18-year) fertilizer experiment. The experiment included five treatments: organic manure, an equal mixture of organic manure and mineral fertilizer, fertilizer NPK, fertilizer NK, and the control (without fertilization). Plant biomass, population sizes of soil OPMB and IPSB were greatly increased (P<0.05) by the application of organic manure and slightly increased by the balanced application of mineral fertilizer, while undiminished AM colonization in wheat root system was only observed in the case of the NK treatment. Compared to balanced fertilization, P-deficiency fertilization resulted in a significant increase (P<0.05) of OPMB-specific mineralization potential (soil P-mineralization potential per OPMB cell) and highest IPSB-specific solubilization potential (soil P-solubilization potential per IPSB cell), suggesting that OPMB and IPSB are likely more metabolically active in P-deficiency fertilized soils after long-term fertilizer management, and mycorrhizal plants are more dependent on AM in P-poor soils than in P-fertilized soils. Our results also showed the different effects of mineral fertilizer versus organic manure on soil P-mineralization and -solubilization potentials, as well as specific potentials of OPMB and IPSB in arable soils.     

添加尿素和无机盐土对秸秆厌氧消化的影响

向厌氧消化体系加入外源添加剂是一种有效且简单的用于提高产气效率的方法。为了解决秸秆厌氧消化原料转化率低、易酸化、厌氧消化时间长等问题,该文选取尿素和无机盐土作为秸秆厌氧消化的添加剂,研究比较不同添加量对玉米秸秆厌氧消化过程产气特性、发酵环境、微生物活性以及物能转化效率的影响。结果表明,对于出现酸化问题且甲烷菌活性较低的厌氧消化系统,添加尿素和无机盐土有利于缓解酸化并促进微生物生长繁殖,三磷酸腺苷（ATP）峰值时的微生物数量可增加2.76×1011-5.31×1011个/L。添加一定量的尿素和无机盐土可使产气高峰提前,添加10%的无机盐土处理组与纯秸秆处理相比,产气高峰可提前4d;但酸化也会削弱尿素和无机盐土对产甲烷过程的促进作用,添加量越大,削弱效果越显著。研究结果可为秸秆厌氧消化的工程应用提供参考。     

滴灌追氮管理对宿根蔗田土壤氮组分及N2O排放的影响

【目的】研究滴灌追氮管理对宿根蔗田土壤氮组分和N₂O排放的影响,揭示影响土壤N₂O通量的土壤因子。【方法】以二代宿根蔗Saccharum officinarum为研究对象,在移动防雨棚内进行2个滴灌灌水量[田间持水量的70%～80%(W0.8)和田间持水量的80%～90%(W0.9)]及3种滴灌追氮比例(等氮量250 kg·hm^-2,其中,N0为用作追肥的氮肥全部施用到土壤中,N5为50%土施追氮、50%用滴灌系统施用,N7为30%土施追氮、70%滴灌追氮)的田间试验。在甘蔗生长的各个时期测定蔗田土壤N₂O通量、pH和氮组分含量,并分析土壤N₂O通量与土壤pH和氮组分含量的关系。【结果】土壤N₂O通量在施用氮肥和灌水后2 d较高,其中,分蘖后期和成熟期W0.9N5处理的土壤N₂O通量显著低于其他处理。W0.9条件下,分蘖后期N5处理的土壤N₂O累积排放量分别比N0和N7低47.3%和11.8%,伸长后期N5处理的...     

植物富集环境污染物的我国研究进展

综述了植物富集环境污染物的研究现状,从植物富集无机污染物,植物富集有机污染物以及植物富集放射性污染物方面进行了探讨,旨在展望植物富集环境污染物的研究趋势。     

微咸水灌溉条件下含黏土夹层土壤的水盐运移规律

黏土夹层影响着土壤水盐运移及分布,为了研究在含黏土夹层的土壤中进行微咸水灌溉时土壤的水盐运移规律,进行了春小麦微咸水灌溉大田试验,并在此基础上运用数值模型对土壤盐分累积趋势进行了模拟预测。结果表明,黏土夹层对土壤水盐运移具有显著的阻碍作用,黏土夹层以上土壤平均含水量、含盐量呈随灌溉水矿化度增大而增加的趋势,黏土夹层以下各处理土壤水盐分布几乎不受微咸水灌溉的影响;大定额冬溉洗盐后,各处理0～70 cm土层最大积盐率仍高达65.7%,部分盐分滞留在黏土夹层以上;土壤盐分分布预测结果表明,微咸水连续灌溉5 a后,灌溉水矿化度为4和5 g/L的处理土壤盐渍化倾向明显,不宜在含黏土夹层地区长期使用矿化度>3 g/L的微咸水进行灌溉,否则将对土壤环境产生严重危害。     

Soil chemical and biochemical properties of a salt-marsh alluvial Spanish area after long-term reclamation

Marisma, one of the largest salt-marsh alluvial areas in SW Spain, has been reclaimed since 1970 by artificial drainage and amendment with phosphogypsum (PG) so as to reduce Na⁺ saturation. Within the reclaimed area, two 250- × 20-m plots were treated as follows: (1) amendment with 25 Mg/ha of PG every 2 to 3 years between 1979 and 2003 (plot PY); (2) like PY but PG treatment stopped after 1997 (plot DR). A contiguous virgin Marisma salt-marsh plot (MV), neither drained nor amended, was the control. In MV, soil microbial biomass C, most enzyme activities and total organic C content were much greater than in PY and DR soils, despite the salinity stress. The decrease in soil organic matter content in PY and DR soils was likely due to cotton-cropping practices, which favoured the organic C mineralisation and nutrients removal by crops. Microbial activity of MV soil, probably stimulated by the rhizodepositions of the natural vegetation, did not suffer from the osmotic effect due to the raising of soil solution ionic strength. Microbial quotient could be ranked as MV > PY > DR, whereas the metabolic quotient had an opposite trend. Thus, both quotients suggested that the interruption of PG amendment was not favouring microbial activity. Principal component analysis clearly identified the chemical and biochemical soil properties mostly affected by the reclamation and also indicated the longer PG amendment in PY plot. Stepwise discriminant analysis identified two physiologically different types of soil microflora, one less active present in the MV virgin soil and another more active present in the reclaimed PY and DR soils.     

Effects of prescribed burning and seasonal and interannual climate variation on nitrogen mineralization in a typical steppe in Inner Mongolia

Fires in grasslands significantly alter nutrient cycling processes. Seasonal climatic changes can interact with fire to further modify nutrient cycling processes. To investigate the effects of fire on soil nitrogen transformation processes and their seasonal change and interannual variability in a typical steppe in Inner Mongolia, we determined the rates of net nitrogen mineralization and nitrification over two growing seasons and a winter following a prescribed spring fire in May 2006. Fire significantly decreased rates of both net nitrogen mineralization and net nitrification during the first growing season and winter following burning. Cumulative net nitrogen mineralization in unburned and burned plots in the 2006 growing season was 133% and 183% higher, respectively, than in the drier 2007 growing season. Nitrogen mineralization apparently occurred in winter and the cumulative net nitrogen mineralization from October 2, 2006, to April 27, 2007 in unburned and burned plots amounted to 1.18 ± 0.25 g N m⁻² and 0.51 ± 0.08 g N m⁻², respectively. Cumulative net nitrogen mineralization was higher in a wet 2006 than in a dry 2007 growing season, indicating that the net N mineralization rate was sensitive to soil moisture in a dry season. Our study demonstrated that a one-time prescribed fire decreased net N mineralization rates only for a short period of time after burning while interannual variation in climate had more significant effects on the process of nitrogen mineralization.