不同促腐条件下秸秆还田对土壤微生物量碳氮磷动态变化的影响

通过2年田间定位试验,研究了冀东地区小麦玉米轮作制度下,不同促腐条件下玉米秸秆配施化肥直接还田对土壤微生物量C���N、P���态变化的影响,并讨论了其与土壤养分和酶活性的关系.结果表明,秸秆配施化肥并调节其C/N条件下,施用促腐剂处理作物各生育期土壤微生物量C���N、P���表现出高于未施用处理的趋势,并使微生物量N、P���到高峰期的时间提前,对土壤养分调控效果较好.土壤微生物量C���N、P���土壤酶活性在作物各生育期均表现为显著和极显著正相关关系,但与土壤碱解氮、有效磷的相关性受到施肥制度和作物生长的强烈影响.

Thermodynamic study of ibuprofen by adiabatic calorimetry and thermal analysis

Molar heat capacities of ibuprofen were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 80 to 400 K. The polynomial functions of C-p,C-m (J K-1 mol(-1)) versus T were established on the heat capacity measurements by means of the least fitting square method. The functions are as follows: for solid ibuprofen, at the temperature range of 79.105 K less than or equal to T less than or equal to 333.297 K, C-p,C-m = 144.27 + 77.046X + 3.5171X(2) + 10.925X(3) + 11.224X(4), where X = (T - 206.201)/127.096; for liquid ibuprofen, at the temperature range of 353.406 K less than or equal to T less than or equal to 378.785 K, C-p,C-m = 325.79 + 8.9696X - 1.6073X(2) - 1.5145 X-3, where X = (T - 366.095)/12.690. A fusion transition at T = 348.02 K was found from the C-p-T curve. The molar enthalpy and entropy of the fusion transition were determined to be 26.65 kJ mol(-1) and 76.58 J mol(-1) K-1, respectively. The thermodynamic functions on the base of the reference temperature of 298.15 K, (H-T - H-298.15) and (S-T - S-298.15), were derived. Thermal characteristic of ibuprofen was studied by thermo-gravimetric analysis (TG-DTG) and differential scanning calorimeter (DSC). The temperature of fusion, the molar enthalpy and entropy of fusion obtained by DSC were well consistent with those obtained by adiabatic calorimeter. The evaporation process of ibuprofen was investigated further by TG and DTG, and the activation energy of the evaporation process was determined to be 80.3 +/- 1.4 kJ mol(-1). (C) 2003 Elsevier B.V. All rights reserved.

长白山次生针阔混交林叶凋落物中有机物分解与碳、氮和磷释放的关系

采用分解袋法,研究了长白山次生针阔混交林内9种树种叶凋落物34个月的分解过程.结果表明:在次生针阔混交林中,不同树种叶凋落物的初始N和P���度存在很大差异,叶凋落物分解速率(k)与初始N浓度和C/N显著相关.有机物剩余百分率与C���余百分率呈显著的线性正相关关系,与N和P���余百分率之间呈显著的二项式回归关系.N和P���余百分率在初期阶段随有机物分解而增加,达到峰值后逐渐降低.随着有机物剩余百分率的下降,C/N和C/P���呈逐渐降低趋势,各种叶凋落物之间C/N和C/P���差异逐渐减小,分解末期分别趋近于23和350.随有机物剩余百分率的降低,N/P���化不明显,当有机物剩余百分率低于25%时,不同树种叶凋落物之间N/P���异显著下降.有机物剩余百分率可用来预测C���N和P���剩余百分率.

Investigation of thermodynamic properties of Co2O3 powder

The isobaric molar heat capacities of powder of Co2O3 were determined by an adiabatic calorimeter in the temperature range from 78 to 350 K. No phase transition takes place in this temperature range. The relationship of C-p,C-m with thermodynamic temperature T was established as C-p,C-m = -5 x 10(-6)T(3) + 0.0026T(2) + 0.0325T + 4.2592 (J K-1 mol(-1)), fitting coefficient R-2 = 0.9996. According to this relationship and the relationships between thermodynamic functions, the thermodynamic functions of powder of C2O3 were derived with 298.15 K as reference temperature. Thermal decomposition of Co2O3 powder was studied through thermogravimetry (TG). The possible mechanism of the thermal decomposition reaction was suggested according to the TG result. (C) 2003 Elsevier Science B.V. All rights reserved.

科尔沁沙地小叶锦鸡儿人工林防风固沙及改良土壤效应研究

为探讨小叶锦鸡儿防风固沙、改良土壤养分状况和生物活性的能力,选取6年和11年生小叶锦鸡儿人工固沙林为对象,以流动沙丘为对照,研究不同年龄固沙林降低风速和风沙流结构特征、土壤有机质和N,P���量、土壤酶的活性以及微生物生物量C,N,P���量的变化特征。结果表明:在小叶锦鸡儿灌木林内,各个高度风速和输沙量均显著低于流动沙丘,防风固沙效果明显。随着小叶锦鸡儿固沙群落发育时间的增长,其综合防风性能提高,土壤有机质、N,P,K含量和生物活性逐渐得到改善。O～30 cm土层中磷酸单酯酶、蛋白酶、脲酶、蔗糖酶、硝酸还原酶、多酚氧化酶、脱氢酶的活性和土壤微生物生物量C,N和P���量均大幅度提高,其中0~10 cm土层增幅最大。土壤酶中蔗糖酶的活性增加最为迅速,6年和11年生固沙林0～10 cm土层分别是流动沙丘的28.58倍和55.2l倍。小叶锦鸡儿不仅具有较好的防风固沙性能,而且表现出强大的改善土壤养分和生物活性的能力,可作为优良的固沙植物材料在科尔沁沙地大面积推广应用。

不同氮磷施肥量对玉米生育期土壤微生物量的影响

通过田间小区试验研究了不同N、P���肥量对玉米生育期土壤微生物量C���N、P���影响。结果表明,不同N、P���肥量对微生物量C���明显影响;施N肥量高(225km/hm~2)时降低微生物量N;当施P���达225 km/hm~2时则对微生物量P���生明显的抑制作用。

施肥对日本落叶松不同根序细根养分浓度的影响

以辽宁东部山区16年生日本落叶松人工林为对象,探讨施肥对落叶松1～5级不同根序等级细根养分浓度的变化.结果表明:不同根序等级细根全碳浓度差异不显著,施肥对各级根序全碳浓度没有显著影响;在前5级根序中,1级根非结构性碳水化合物(TNC)浓度最低,N和P���度最高;而5级根TNC���度最高,N和P���度最低.TNC���度随着根序增加而升高,N和P���度则相应下降.施肥仅对1级根组织中N和P���度有显著影响;不同根序根组织中C/N/P���有明显差异,1级根平均C/N/P���423∶16∶1,5级根为726∶16∶1,随着根序增加,C���3种元素中的比例显著增加,而N的比例变化不大.施N肥并没有改变C���比例;但施P���或施N+P���均降低了前3级根(0～10cm)或前2级根(10～20cm)C���N在3种元素中的比例.

田块尺度下土壤磷素的空间变异性

采用经典统计学与地统计学相结合的方法,对中国科学院沈阳生态实验站30 m×42 m样地进行网格法分层(0~10和10~20 cm)取样,研究了田块尺度下土壤全P���Olsen-P���空间变异特征.结果表明,49对样本土壤Olsen-P���变异系数(46.56%~56.42%)远高于全P(11.68%~13.33%);全P���Olsen-P���有较好的空间结构且具有较相近的空间相关距离.最佳理论模型的参数显示各变量空间变异主要受结构性因素的影响,各变量半方差变异函数的C/(C0+C)均高于66%.全P���Olsen-P���间及在2个土层之间均具有较相似的空间分布格局.变异系数结合空间格局分析可以大大降低试验取样的数量.

土壤水分梯度对阔叶红松林结构的影响(英文)

2002年8月,在吉林省白河林业局红石林场(12755E,4230N),沿着一个山坡设置了一个长宽为112m8m、包含14个样方的样带。调查了群落结构、0-10cm和10-20cm的土壤含水量、枯落物现存量及其C���N、P���量,主要树种的叶片和枝条的C���N、P���量。沿着山坡的不同位置土壤含水量的不同导致阔叶红松林的群落结构发生变化。蒙古栎的比例随着土壤含水量的下降而逐渐升高,而其他主要阔叶树种则逐渐减少乃至消失。枯落物的水分变化趋势与土壤一致。在不同坡位枯落物的分解状况不同,干重差异显著。坡下枯落物含量较坡上的丰富,部分原因在于群落结构的变化。水分和养分含量的变化影响了枯落物的成分、降解及其养分的释放,进一步影响了林木的生长速度和林分结构并最终影响整个生态系统。图7表2参14。

Structure and electrochemical characteristics of RENi3 alloy

The RENi3 (RE = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Y) series compounds have been prepared by arc melting constituent elements under Ar atmosphere. X-ray diffraction (XRD) analysis reveals that the as-prepared alloys have different lattice parameters and cell volumes, depending on different rare earth (RE) element. The electrochemical characteristics, including the electrochemical capacity, P-C isotherms, high rate chargeability (HRC) and high-rate dischargeability (HRD), of these alloys have been studied through the charge-discharge recycle testing at different temperatures, charge currents and discharge currents. The results show that YNi3 has the largest cell volume, smallest density, and moreover, it shows more satisfactory electrochemical characteristics than other alloys, including discharge capacity, HRC, HRD and low temperature dischargeablity.

Crystallographic and electrochemical characteristics of La0.7Mg0.3Ni3.5-x (Al0.5Mo0.5)(x) (x=0-0.8) hydrogen storage alloys

The crystal structure, hydrogen storage property and electrochemical characteristics of the La0.7Mg0.3Ni3.5-x(Al0.5Mo0.5), (x=0-0.8) alloys have been investigated systematically. It can be found that with X-ray powder diffraction and Rietveld analysis the alloys are of multiphase alloy and consisted of impurity LaNi phase and two main crystallographic phases, namely the La(La, Mg)(2)Ni-9 phase and the LaNi5 phase, and the lattice parameter and the cell volume of both the La(La, Mg)(2)Ni-9 phase and the LaNi5 phase increases with increasing A] and Mo content in the alloys. The P-C isotherms curves indicate that the hydrogen storage capacity of the alloy first increases and then decreases with increasing x, and the equilibrium pressure decreases with increasing x. The electrochemical measurements show that the maximum discharge capacity first increases from 354.2 (v = 0) to 397.6 mAh g(-1) (x = 0.6) and then decreases to 370.4 mAh g(-1) (x= 0.8). The high-rate dischargeability of the alloy electrode increases lineally from 55.7% (x=0) to 73.8% (x=0.8) at the discharge current density of 1200 mA g(-1). Moreover, the exchange current density of the alloy electrodes also increases monotonously with increasing x.

Crystal growth and structural analysis of PrMnO3 and TbMnO3

Single crystals of PrMnO3 and TbMnO3 were grown by floating zone method and the crystal structure was determined by single crystal X-ray diffractometry. The structure of these compounds belongs to the orthorhombic system (space group is Pnma, No. 62) with the lattice parameters alpha approximate to root (.) - a(p), b approximate to 2 (.) a(p) , c approximate to root 2.a(p) and Z = 4, where a(p) is ideal cubic perovskite cell parameter.

Scanning electrochemical microscopy study of electron transfer across the water/1,2-dichloroethane interface induced by common ions

In this work, we report the reverse electron transfer reaction between TCNQ in 1, 2-dichloroethane (DCE) and ferrocyanide in water. This process is a thermodynamic unfavorable reaction and the reverse electron transfer reaction can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfacial potential difference. In our case, the potential determining ions are tetrabutylammonium ion(TBA(+)) and tetraphenylarsonium ion (TPAs+). The effects of the concentrations of TBA(+) and TPAs+ in two phases and other parameters have been studied in detail. The apparent heterogeneous rate constants(k(i)) were obtained under different values of K-p(K-p=c(i)(w)/c(i)(o)) for both cases by fitting the SECM approach curves with theoretical ones and the results showed that they were controlled by the interfacial potential differences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.

Synthesis and polymerization of some macrocyclic (arylene ether sulfone) containing cardo groups and macrocyclic (arylene ether ketone sulfone) oligomers

Some novel macrocyclic (arylene ether sulfone) containing cardo groups and (arylene ether ketone sulfone) oligomers have been synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-difluorophenylsulfone with bisphenols in the presence of anhydrous potassium carbonate under a pseudo-high-dilution condition. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), fast atom bombardment mass spectrometry (f.a.b.-m.s.), nuclear magnetic resonance spectrometry (n.m.r.) and single-crystal X-ray structure analysis confirms their cyclic nature, and the composition of the oligomeric mixtures is provided by g.p.c. analysis. Ring polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 59.1 k was achieved by heating at 290 degrees C for 40 min in the presence of a nucleophilic initiator. (C) 1998 Elsevier Science Ltd. All rights reserved.

渤海沉积物中氮的赋存形态及其在循环中的作用

为揭示渤海沉积物中氮的生物地球化学循环过程，本文应用自然粒度下的分级分离浸取方法首次对渤海沉积物中氮的形态进行了研究，获得了氮形态分布的地球化学特征；将沉积物氮中可转化和非转化部分定量区别开，并对可转化态中各形态氮对其循环贡献的大小进行了评估；结合底栖生物的分布初步探计了沉积物中氮与生物生产的关系及底栖生物对氮循环的影响。得到的主要结论包括：渤海沉积物中氮的形态分布特征及其控制因素。表层沉积物中IEF-N、CF-N、IMOF-N和OSF-N占TN的比例分别为3.67%，0.31%，0.42%和26.45%，OSF-N是可转化态氮的优势形态。IEF-N 中NH_4~+和NO_3~-具有不同的成岩机制：NH_2~+主要受OC���Es和粘土矿物性质影响，NO_3~-与水体分布密切相关。CF-N含量最小，主要受沉积环境pH值的影响。IMOF-N主要由NH_4~+在Fe~（3+）上的吸附形成，受沉积物的氧化还原环境控制。OSF-N除与物质来源有关外，受到粘土矿物性质及沉积物粒度的影响。Fe、Mn和Co对IEF-N和IMOF-N的成岩作用影响明显，Cu、Pb和Mo对OSF-N的分布产生影响，二者作用的机理不同。表层样中，约69.15%的氮经过早期成岩作用而埋藏，短期内不再参与循环。氮的埋藏通量与沉积物聚积速率呈显著正相关，同时受温度、Eh、OC���盐度、硫化物含量等因素影响。沉积物中C/N和N/P���呈现异常的低值，前者主要是由于沉积物中保留了大量的无机氮，后者主要因为陆地排放大量磷入海以及磷的埋藏效率高于氮所致。柱状样中，IEF-N基本随深度减小，IMOF-N随深度有突变现象，OSF-N随深度的变化表明了矿化作用进行的程度。对沉积物中生源要素分解速率常数有：N>P>C>Si。表层沉积物中可转化态氮占总氮的比例高于深层沉积物。OC/ON随深度减小表明沉积物通过某种机制富集了有机氮。各形态氮在氮循环中作用及渤海氮循环收支。对渤海沉积物中可转化态氮的量进行了估算，IEF-N、CF-N、IMOF-N和OSF-N分别为3.657 * 10~8kg，2.794 * 10~7 kg，3.832 * 10~7kg和2.372平共处* 10~9kg；结合室内模拟的氮的界面交换通量，估算其完全释放所需的时间分别为2.15a，0.16a，0.225a和13.94a。各形态氮释放的顺序与其结合牢固程度一致，即IEF-N>CF-N >IMOF-N>OSF-N，其对界面交换的贡献大小则随时间尺度大小发生变化：随时间尺度增加，IEF-N、CF-N、IMOF-N的贡献逐渐减小，OSF-N的贡献逐渐增大，当时间尺度大到足以使四态氮完全释放时，其贡献的大小与各形态氮的量一致即OSF-N（84.6%）>IEF-N（13.0%）>IMOF-N（1.4%）>CF-N（1.0%）。非转化态氮占总氮的 69.15%，其中由于颗粒物包裹导致的“非转化态”氮为49%，说明粒度的影响非常重要。IEF-N和OSF-N主要存在于颗粒物质外层，是循环的主要参与者，CF-N和IMOF-N绝大部分在内层，对循环的贡献很小。水体中再循环的氮对初级生产力的贡献（74.4%）比沉积物中再循环氮的贡献 （26.1）大得多，二者对生态系统的作用不同，水体再生的营养盐通常在较长的时间尺度上维持初级生产力的平衡，而沉积物中的再生则在很短的时间内通过强烈的混合作用提高初级生产力。沉积物中氮与生物生产的关系及底栖生物对沉积物氮循环的影响。IEF-N和OSF-N的分布均与初级生产力以及浮游植物个体数量的分布具有一定的相似性。沉积物中的IEF-N的作用相当于一个氮营养盐的“储存库”对初级生产力产生影响，其作用机制类似于水体富营养化的正反馈机制。IEF-N能对赤潮的发生起加速作用。底栖生物的分布与氮形态分布具有正的相关性：莱洲湾内IEF-N和OSF-N的分布与该区域高生物量和高密度的大型底栖动物分布一致，说明在底栖生物活动活跃的区域营养盐的再生和流动是高效而迅速的。生物扰动能加速矿化作用的进行，使沉积物在一定深度范围内NH_4~+含量增加，大型底栖动物的灌溉作用使NO_3~-在深层仍有较高的分布。底栖生物的不同种群对营养盐变化的响应不同。