黄土高原坡地苹果园土壤肥力及矿质氮累积分析

采用田间取样与室内分析相结合的方法,研究了黄土高原坡地苹果园肥力状况与矿质氮累积。结果表明,坡地苹果园土壤肥力低,氮、磷严重缺乏,钾相对丰富,土壤属于砂壤土,通气性强,保肥、保水性差。0—60cm土层土壤有机质含量为9.24～28.12g/kg,全氮为0.22～0.60g/kg,速效磷为0.17～16.08mg/kg,速效钾为80.06～168.39mg/kg;黄土高原坡地苹果园中NO3-—N有深层累积分布,累积深度大于2m,在180—200cm层最高累积量达249.61kg/hm2,而NH4+—N无深层累积。不同施肥处理对土壤剖面中的NH4+—N和NO3-—N含量分布影响不同,对NH4+—N含量和分布影响不明显,但不同施肥方式对NO3-—N含量分布影响显著。施加氮肥促进NO3-—N深层累积,施加磷肥有助于降低土层中的NO3-—N含量,缩小富集量的分布范围。

农田生态系统土壤有机碳库及其影响因子

土壤有机碳(SOC)的数量和质量在很大程度上与维持和提高土壤肥力密切相关。农田生态系统土壤碳库研究一直是农业、生态和环境领域的一个主要方向。土地利用、耕作、作物类型、种植密度、灌溉、施肥以及其他人为活动等,对农田生态系统土壤有机碳库的变化均能产生影响。本文综合评述了农田生态系统土壤有机碳库及其影响因子,土壤碳截获潜力,维持和提高土壤有机碳库的措施,以及农田土壤碳截获在温室气体减排及气候变化中的潜在作用等,最后提出了农田生态系统土壤有机碳库研究的主要方向。

知识和智慧的载体

前　　言　　在新世纪开初 ,欣逢《植物生理学通讯》创刊 5 0周年。本刊新组建的编委会决定循 4 0周年时的前例 ,也举行一次活动(包括出版“特辑”和召开座谈会 )。于是我们约请了一些人士撰写了纪念文稿 ,同时也收到了一些自发来稿 ,编辑了这个“特辑”。作者从九十高龄的娄成后先生 ,直到年轻的在读研究生 ,他们在文章中高度评价了本刊的作用和成就 ,同时也对本刊寄予了殷殷厚望 ,可以说代表了当今植物生理学界几代人的心声。这里 ,谨向他们表示由衷的感谢 !文稿中大都冠有“祝贺《植物生理学通讯》创刊 5 0周年”的副标题 ,为避免重复 ,一律舍去了。还有几篇文章题目雷同 ,我们作了改动。并此说明。———编者

小叶锦鸡儿防风固沙林稳定性研究

针对科尔沁沙地小叶锦鸡儿固沙林在持续高温干旱条件下出现稳定性波动的问题 ,选择 2、5、15、35 a人工群落和天然群落进行对比研究 ,探讨了人工小叶锦鸡儿防风固沙林物种多样性在 35 a间的变化以及对大气持续干旱的抵抗力和对外界干扰的恢复能力。流动沙丘固定后 ,固沙林内草本植物迅速侵入 ,其后则缓慢发展并处于相对稳定状态 ,植物种类数保持在 2 0～ 2 3种。但在人工固沙群落中 1年生植物在种类数和数量上始终处于优势地位 ,而天然群落则是多年生植物占优势。人工固沙群落物种多样性指数逐年提高 ,但明显低于天然群落。在受到大气持续高温干旱的干扰时 ,人工群落土壤条件极度恶化 ,出现了明显的干沙层 ,最深达 14 0 cm ,叶片含水量极度降低 ,植物生长停止。沙地植物群落对牲畜取食均具有一定的补偿的能力 ,在啃食较轻时表现为超补偿现象。通过建立数学模型分析 ,人工群落个体的补偿点和超补偿点明显低于天然群落。采用冗余理论对植物群落稳定性机制进行了论述 ,认为冗余结构的变化是导致群落稳定性变化的内在原因。对现有人工小叶锦鸡儿固沙林的稳定性进行了评价 ,并认为 15 a左右人工固沙林正处于相对稳定并缓慢发展状态。对于稳定的人工固沙群落应具备以下条件 :(1)适于当地环境条件 ;(2 )对外界

中国的褐褶菌属(担子菌门,非褶菌目)的研究(英文)

对中国褐褶菌属Gloeophyllum的种类进行了研究,并记录了此属中10个种。其中喜干褐褶菌Gloeophyllumprotractum是中国的新记录种,发现于黑龙江和四川省的针叶树倒木上。根据中国的材料详细描述了此种,并列出褐褶菌属的检索表。

湘西多金属矿区汞铅污染土壤的环境质量

以湘西典型多金属矿区为现场,研究了矿区土壤中汞、铅等重金属污染状况及成因.结果表明,湘西矿区是汞、铅污染严重的区域,与中国土壤元素背景值相比,汞矿区土壤中汞、铅含量分别增加1315倍和3.1倍,铅锌矿区土壤中汞、铅含量分别增加14.8倍和16.1倍.运用Muller地积指数进行风险评价,证实湘西矿区是汞、铅等重金属的复合污染区,汞矿区汞污染以极重污染为主,铅污染以中度和轻污染为主;铅锌矿区铅污染以中度和中-重污染为主,汞污染以中-重污染为主.矿区土壤中的重金属污染物来源和分布受原生地球化学条件的控制,而人为采矿活动对矿区土壤中汞、铅的污染格局产生重要影响.

Relationship between charge transfer energies of Yb3+ and Sm3+ and crystal environmental factor

Relationship between charge transfer energies E-CT of Yb3+ and Sm3+ and environmental factors h(e) in various crystals was investigated using a dielectric chemical bond method. Both results show that they have an exponential relation E-CT = A+B exp(-kh(e)), but the exponential factors are different, which indicates that the interaction between the rare earth ions and environment is connected with the kind of rare earth ion. This result provides a method of determining charge transfer energies of Yb3+ and Sm3+ from a crystal structure.

Novel proton exchange membranes based on water resistant sulfonated poly[bis(benzimidazobenzisoquinolinones)]

Novel water resistant sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBIs) were synthesized from 6,6'-disulfonic-4,4'-binaphthy]-1,1',8,8'-tetracarboxylic dianhydride (SBTDA) and various aromatic ether tetraamines. The resulting polymers with IEC in the range of 2.17-2.87 mequiv g(-1) have a combination of desired properties such as high solubility in common organic solvents, film-forming ability, and excellent thermal and mechanical properties. Flexible and tough membranes, obtained by casting from m-cresol solution, had tensile strength, elongation at break, and tensile modulus values in the range of 87.6-98.4 MPa, 35.8-52.8%, and 0.94-1.07 GPa. SPBIBI membranes with a high degree of sulfonation displayed high proton conductivity and a good resistance to water swelling as well. SPBIBI-b with IEC of 2.80 mequiv g(-1) displayed the conductivity of 1.74 x 10(-1) S cm(-1) at 100 degrees C, which was comparable to that of Nafion (R) 117 (1.78 x 10(-1) S cm(-1), at 100 degrees C).

Investigations on the adsorption behavior of Neutral Red on mercaptoethane sulfonate protected gold nanoparticles

A detailed investigation on the adsorption behavior of Neutral Red (NR) molecules on mercaptoethane sulfonate-monolayer protected gold clusters (MES-MPCs) has been conducted by the spectroscopic method. It is found that cationic NR molecules are adsorbed on the negatively charged MPCs surfaces via electrostatic attractive forces. The absorption study shows that the optical properties of NR molecules are significantly influenced upon the adsorption. Based on the electrostatic adsorption nature and the excellent stability of MES-MPCs against the electrolytes, this association can be released by the addition of electrolyte salts, which can be monitored by both absorption and fluorescence spectroscopy. In addition, dication Ca2+ is found to be more effective in the release of NR than univalent Na+. Moreover, the MES-MPCs exert energy transfer quenching of NR fluorescence by both static and dynamic quenching. However, static quenching seems to be the dominating quenching mechanism. Furthermore, this energy transfer quenching exhibits strong dependence of Au core size, and 5.0 nm MPCs show stronger ability in quenching the NR fluorescence than that of 2.7 nm MPCs.

The microstructure and mechanical properties of Mg-8Zn-8Al-4RE magnesium alloy

The Mg-8Zn-8Al-4RE (RE = mischmetal, mass%) magnesium alloy was prepared by using casting method. The microstructure and mechanical properties of as-cast alloy, solid solution alloy and aged alloy samples have been investigated. Optical microscopy, X-ray diffractometery and scanning electron microscope attached energy spectrometer were used to characterize the microstructure and phase composition for the alloy. Net shaped tau-Mg-32(Al,Zn)(49) phase was obtained at the grain boundary, and needle-like or blocky Al11RE3 phase disperses in grain boundary and alpha-Mg matrix. The tau-Mg-32(Al,Zn)(49) phase disappeared during solution treatment and a new phase of Al(2)CeZn2 formed during subsequent age treatment. The mechanical properties were performed by universal testing machine at room temperature, 150 degrees C and 200 degrees C, separately. The ultimate tensile strength of as-cast alloy is lower compared to an age treatment alloy at 200 degrees C for 12h. The strengths decreased with enhancing test temperature, but elongation has not been effect by age treatment.

Mesoporous acid solid as a carrier for metallocene catalyst in ethylene polymerization and a catalyst in catalytic degradation of polyethylene

The possibility of mesoporous acid solid as a carrier for metallocene catalyst in ethylene polymerization and catalyst for polyethylene (PE) catalytic degradation was investigated. Here, HMCM- 41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves (SAPO1 and SAPO2) were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPO1 mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.