Observations of Kuroshio intrusion into the South China Sea

To discuss the intrusion of the Kuroshio into the SCS, we examined the mixing between the North Pacific and South China Sea (SCS) waters based on in-situ CTD data collected in August and September 2008 and the moored ADCP data taken from mid September 2008 to early July 2009. The CTD survey included four meridional sections from 119A degrees E to 122A degrees E around the Luzon Strait, during which pressure, temperature, and salinity were measured. The CTD data show that the isopycnal surface tilted from the SCS to the North Pacific; and it was steeper in the lower layers than in the upper ones. Meanwhile, we found strong vertical mixing taken place in the areas near 121A degrees E. The Kuroshio in high temperature and salinity intruded westward through Luzon Strait. The frequency of buoyancy was one order of magnitude greater than that of the common ones in the ocean, suggesting stronger stratification in the northeastern SCS. On the other hand, the long-term ADCP data show that before late October 2008, the direction of water flow in the SCS was eastward, and from November 2008 to late February 2009, it turned northwestward in the layers shallower than 150 m, while remained unchanged in deep layers from 200 to 450 m. From March to June 2009, the direction shifted with increasing depth from northward to southward, akin to the Ekman spiral. EOF analysis of the current time series revealed dominant empirical modes: the first mode corresponded to the mean current and showed that the Kuroshio intrusion occurred in the upper layers only from late December to early March. The temporal coefficient of the first and the second mode indicated clearly a dominant signal in a quasi-seasonal cycle.

海水二氧化碳含量变化对颗粒碳酸钙溶解影响的研究

由于人类活动等影响，致使近一个世纪以来大气中CO_2含量持续上升。海洋是大气CO_2含量变化的一个巨大缓冲器，进入大气的CO_2约有40%被海洋吸收，这部分CO_2将与水体中二氧化碳系统作用。随着大气CO_2含量的继续增加，可能会导致浅海水体中碳酸钙的不饱和，沉积物CaCO_3将发生溶解，因而对某些海洋生物生长产生影响。因此，联合国教科文组织于1980年提出，要求对浅海CaCO_3溶解的问题予以重视。可是，因难以寻得适合此项研究的海域，以及海水CO_2系统本身的复杂性，至今尚未有人进行这方面的系统研究。中国渤、黄海水深较浅，受黄河水影响，沉积物中CaCO_3含量高，大气CO_2含量变化在较短时间内即可作用到海底，是进行上述研究的理想场所。鉴于海水CO_2系统的复杂性，特以实验室模拟，结合部分现场样品，进行分析探讨。以实验室模拟实验，得出方解石在不同二氧化碳分压，不同温度，总压力为1atm条件下的溶解过程，并以浅海沉积物样品进行了对照实验。在浅海区域，碳酸钙处于过饱和，颗粒CaCO_3进入沉积后，由于有机碳分解，导致部分CaCO_3发生溶解，对此，进行了南黄海沉积物柱样CaCO_3含量的分析测定，并加以讨论。另外，对大气二氧化碳含量增加，导致浅海碳酸钙饱和度降低，以致于颗粒碳酸钙发生溶解的可能性进行了探讨。

青海湖北岸草甸草原牧草生物量季节动态研究

2007年5-9月在青海湖北岸的高寒草甸草原,定位研究天然草地地下、地上和总生物量的变化动态。结果表明:青海湖北岸高寒草甸草原天然牧草地上生物量有明显的季节变化,在生长季呈单峰曲线,生育初期地上生物量最小,8月中旬达到最大值,为223.0 g/m2;地下生物量空间分布为倒金字塔型,010 cm层地下生物量占地下生物总量的65%,010、1020和2040 cm层牧草地下生物量在5-9月均表现为"N"型变化规律;地下生物量周转值为0.45;在生长期内地下生物量的积累远远大于地上生物量的积累,地下生物量峰值也比地上生物量峰值提前;群落根冠比先降后升,平均值为16.1。

人工栽培唐古特大黄中蒽醌含量水平的分析

采用醋酸镁比色法测定青海省不同海拔种植基地中栽培唐古特大黄的总蒽醌含量,并和野生大黄药材进行了比较.结果表明,在海拔较高地区栽培的二、三年生唐古特大黄中,其总蒽醌含量均明显高于较低海拔地区栽培的同龄唐古特大黄,3年生人工栽培大黄总蒽醌含量只有野生大黄药材的一半左右.

三角草属和冠毛草属的系统关系与地理分布的初步研究

根据外部形态上小穗的结构特征分析了针茅族中三角草属和冠毛草属的系统发育关系, 并结合地理分布和生境条件对两属植物的起源中心进行了探讨。结果表明: 三角草属和冠毛草属是针茅族中亲缘关系最近的类群; 冠毛草属高级于三角草属; 三角草属中的三角草是两属植物中最原始的种型, 它可能既派生了属内的假冠毛草, 同时又派生了属外绝灭了的黑穗茅祖种, 而黑穗茅祖种又在自身属内间接衍生出了冠毛草和单蕊冠毛草; 冠毛草属和三角草属皆起源于我国的西藏地区,其中三角草属可能源于西藏西部, 冠毛草属可能源于西藏东部。

高寒草甸植物地上生物量生长过程的某些特征

分析了高寒草甸植物地上生物量对积温变化的响应。结果表明, 生物量干物质积累(GW ) 与积温(ΣT ) 成明显的正相关关系, 可用逻辑斯谛(Logistic) 曲线方程: GW = 428.5061/〔1+ exp (2. 6076- 0. 0038ΣT ) 〕来描述。通过模拟方程可知, 在日平均气温稳定通过≥0℃积温达678℃·d 左右时地上生物量增长速率最高; 积温在335～ 1020℃·d 之间为生物量平均增长率积累最快的时段。在降水条件适宜的状况下, 未来牧草生长期内气温升高1℃, 高寒草甸植物年产量将有所提高。

河西走廊棘豆毒草中的硒及其与牲畜中毒关系研究

河西走廊地区草原生态环境,棘豆等毒草泛滥成灾,导致大量牲畜中毒死亡。棘豆毒草导致的牲畜中毒症状与历史上马可波罗记载的古代肃州牲畜毒草中毒症状及其相似。为了确定马可波罗所记载的肃州牲畜毒草中毒是否与硒有关,本项研究对河西走廊地区主要草原畜牧区肃南县草原发育的棘豆属植物及其土壤中的硒进行了测定,测定结果表明:土壤硒含量平均值为0.205±0.173mg/kg,与世界平均土壤硒含量相近。棘豆属植物小花棘豆根、茎叶的硒平均含量分别为0.112±0.038mg/kg(0.052～0.174mg/kg),0.102±0.027mg/kg(0.066～0.158 mg/kg);黄花棘豆全株硒平均含量为0.066±0.009mg/kg(0.058～0.078mg/kg),种子硒:0.107mg/kg。可见该区棘豆属毒草硒含量远低于能导致一般动物中毒的3mg/kg植物硒含量。根据肃南县棘豆毒草发育的地理位置、牲畜中毒症状调查及其硒含量测定的结果,本文认为马可波罗所记载的中国西部肃州牲畜毒草中毒是棘豆属毒草中毒,其主要毒素成分不是硒。

Synthesis and characterization of gallium-based perovskite-type dense membrane with oxygen semipermeability

La0.15Sr0.85Ga0.3Fe0.7O3-delta (LSGFO) and La0.15Sr0.85Co0.3Fe0.7O3-delta (LSCFO) mixed oxygen-ion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding dense membranes were fabricated. The properties of the oxide powders and membranes were characterized with combined SEM, XRD, H-2-TPR, O-2-TPD techniques, mechanical strength and oxygen permeation measurement. The results showed that LSGFO had much higher thermochemical stability than LSCFO due to the higher valence stability of Ga3+. After the temperature-programmed reduction by 5% H-2 in Ar from 20 degreesC to 1020 degreesC, the basic perovskite structure of LSGFO was successfully preserved. LSGFO also favors the oxygen vacancy formation better than LSCFO. Oxygen permeation measurement demonstrated that LSGFO had higher oxygen permeation flux than LSCFO, but they had similar activation energy for oxygen transportation, with a value of 110 and 117 kJ . mol(-1), respectively The difference in oxygen permeation fluxes was correlated with the difference in oxygen vacancy concentrations for the two materials.

UV Raman spectroscopic study on the synthesis mechanism of zeolite X

The synthesis of zeolite X is characterized by UV Raman spectroscopy, NMR spectroscopy, and X-ray diffraction. UV Raman spectra of the liquid phase of the synthesis system indicate that AI(OH); species are incorporated into silicate species, and the polymeric silicate species are depolymerized into monomeric silicate species during the early stage of zeolite formation. An. intermediate species possessing Raman bands at 307, 503, 858 and 1020 cm(-1) is detected during the crystallization ill the solid phase transformation. The intermediate species is attributed to the beta cage, the secondary building unit of zeolite X. A model for the formation of zeolite X is proposed, which involves four-membered rings connecting to each other via six-membered ring to form beta cages, then the beta cages interconnect via double six-membered rings to form the framework of zeolite X. (C) 2001 Elsevier Science B.V. All rights reserved.