大兴安岭林区火烧迹地木腐菌主要类群的初步研究

对大兴安岭林区火烧迹地的 17种主要木腐菌进行了报道 ,并就它们的生态习性和生态功能进行探讨 .通过对火烧林分和非过火林分主要木腐菌类群变化的研究 ,确定在火烧迹地森林生态系统演替过程中的先锋菌物主要有 8种 ,常见菌 4种 ,以及在寒温带针叶林生态系统中的珍稀和濒危的木腐菌 3种 ,并探讨了珍稀或濒危菌物的保护对策 .

黄土高原南部3种农田土壤剖面坚实度的变化规律

为了揭示黄土高原南部地区不同质地类型土壤剖面坚实度的变化及其与土壤含水率的定量关系,以黄墡土、土娄土、裸露在地表的粘化层耕作剖面为研究对象,定位观测其0~45 cm土壤坚实度与含水率的变化。结果表明,黄墡土、土娄土、裸露在地表粘化层耕作剖面的犁底层平均坚实度均大于耕层,犁底层平均坚实度较耕层分别高194.8%,87.3%,10.4%;剖面土壤质地越粘其平均坚实度越大;土壤坚实度与含水率呈负相关关系;土壤坚实度变化速率为0时,以上3种土壤剖面临界含水率分别为0.1712,0.1757,0.1835;质地不同的土壤剖面坚实度时空变化特征有差异,其中黄墡土剖面0~20 cm土层土壤坚实度为350~500 kPa,受土壤含水率变化的影响较小;20~30 cm土层土壤的坚实度为500~1400 kPa,不易受外界环境影响;30 cm以下土层土壤坚实度为700~1600 kPa,受土壤含水率变化影响较大。土娄土剖面0~40 cm土层土壤坚实度为600~1200 kPa,受含水率变化影响较大;40 cm以下土层土壤坚实度稳定在1 800 kPa左右。粘化层剖面0~15 cm土层土壤坚实度在2000 kPa左右,受环境影响较...

细河河水及其沿岸地下水水质的有机污染特征

调查了沈阳市细河河水及其沿岸地下水水质中石油类和美国环保局(USEPA)"黑名单"上的16种优先控制多环芳烃(PAHs)的有机污染现状,评价细河污染带来的生态风险。结果表明:细河河水中石油类浓度和16种PAHs总浓度范围分别为0.031～1.819mg.L-1和0.026～0.384μg.L-1,平均浓度分别为1.007mg.L-1和0.151μg.L-1;细河沿岸地下水中石油类浓度和16种PAHs总浓度范围分别为0.020～0.987mg.L-1和0.051～0.389μg.L-1,平均浓度分别为0.364mg.L-1和0.133μg.L-1;细河河水和地下水中的石油类污染严重;河水中的PAHs浓度在流经规模较大的城镇或乡镇处出现高值点,苯并(b)荧蒽和苯并(k)荧蒽在河水与地下水中的检出率较高,对水生生态系统健康构成了潜在的威胁。

Spontaneous formation of two-dimensional gold networks at the air-water interface and their application in surface-enhanced Raman scattering (SERS)

Two-dimensional (2-D) gold networks were spontaneously formed at the air-water interface after HAuCl4 reacted with fructose at 90 degrees C in a sealed vessel, in a reaction in which fructose acted as both a reducing and a protecting agent. Through fine-tuning of the molar ratio of HAuCl4 to fructose, the thus-formed 2-D gold networks can be changed from a coalesced pattern to an interconnected pattern. In the coalesced pattern, some well-defined single-crystalline gold plates at the micrometer-scale could be seen, while in the interconnected pattern, many sub-micrometer particles and some irregular gold plates instead of well-defined gold plates appeared. It is also found that the 2-D gold networks in the form of an interconnected pattern can be used as substrates for surface-enhanced Raman scattering (SERS) because of the strong localized electromagnetic field produced by the gaps between the neighboring particles in the 2-D gold networks.

Influence of annealing on structure of poly(aryl ether ether ketone ketone) revealed by SAXS

Structural studies of poly(aryl ether ether ketone ketone) (PEEKK) using small-angle X-ray scattering and one-dimensional electron density correlation function methods revealed that its aggregated state structure was significantly influenced by the annealing temperature. The long period L, the average thickness of the lamellae d, the electron density difference between the crystalline and amorphous regions eta(c) - eta(a), and the invariant Q increased with increasing annealing temperature, but it was opposite to the case of the specific inner surfaces O-s. A transition zone existed between the traditional "two phases" with a dimension about 0.5 nm for semicrystalline PEEKK. (C) 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1829-1835, 1998.

用双色三光子共振光电离光谱法测量铀原子奇宇称高激发态能级

数以千计的铀原子能级正在发现之中,但铀原子光谱复杂,给测定工作带来很多困难。绝大多数铀原子能级信息是在常规光源中(如空心阴极或无电极放电灯)由发射或者吸收光谱分析所获得,其光谱数据大多数属于铀原子低能级和中间态能级,高激发态极少。近几年来利

Wangia profunda gen. nov., sp nov., a novel marine bacterium of the family Flavobacteriaceae isolated from southern Okinawa Trough deep-sea sediment

An orange-pigmented, Gram-negative, nonmotile, strictly aerobic and oxidase- and catalase-positive bacterium (SM-A87(T)) was isolated from the deep-sea sediment of the southern Okinawa Trough area. The main fatty acids were i15 : 0, i17 : 0 3OH, i15 : 1 G, i17 : 1 omega 9c, 15 : 0, i15 : 0 3OH and summed feature 3 (comprising i-15 : 0 2OH and/or 16 : 1 omega 7c). MK-6 was the predominant respiratory quinone. DNA G+C content was 35.8 mol%. Flexirubin-type pigments were absent. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain SM-A87(T) formed a distinct lineage within the family Flavobacteriaceae, with < 93% sequence similarity to the nearest strain of genus Salegentibacter. Moreover, strain SM-A87(T) could be distinguished from the nearest phylogenetic neighbors by a number of chemotaxonomic and phenotypic properties. On the basis of polyphasic analyses, it is proposed that strain SM-A87(T) be classified in a novel genus and a new species in the family Flavobacteriaceae, designated Wangia profunda gen. nov., sp. nov. The type strain is SM-A87(T) (CCTCC AB 206139(T)=DSM 18752).

A unified criterion for initiation of sediment motion and inception of sheet flow under water waves

A unified criterion is developed for initiation of non-cohesive sediment motion and inception of sheet flow under water waves over a horizontal bed of sediment based on presently available experimental data. The unified threshold criterion is of the single form, U-o = 2 pi C[1 + 5(T-R/T)(2)](-1/4), where U-o is the onset velocity of sediment motion or sheet flow, T is wave period, and C and T-R are the coefficients. It is found that for a given sediment, U-o initially increases sharply with wave period, then gradually approaches the maximum onset velocity U-o = 2 pi C and becomes independent of T when T is larger. The unified criterion can also be extended to define sediment initial motion and sheet flow under irregular waves provided the significant wave orbital velocity and period of irregular waves are introduced in this unified criterion.

牦牛暖季放牧对牧草消化率的影响

通过垂穗披碱草-星星草混播草地连续3个放牧季的牦牛放牧试验,对不同放牧强度下牧草的消化率进行了研究.结果表明:放牧强度对牦牛所食牧草中酸性洗涤纤维消化率的影响极显著(P＜0.01),对粗纤维消化率的影响显著(P＜0.05),而对所食牧草中的总能、粗蛋白、粗灰分和中性洗涤纤维的影响不显著(P＞0.05);放牧时间对中性和酸性洗涤纤维的影响极显著(P＜0.01),而对牧草总能、粗蛋白、粗纤维和粗灰分的影响不显著(P＞0.05).尽管牦牛的采食量均随放牧强度的增加而减小,但牦牛对采食牧草各营养成分的消化率并未出现规律性变化.

宣龙式赤铁矿含矿岩系的成矿过程研究

Xuanlong-type Hematite Deposits, distributed in Xuanhua and Longguang area in Hebei province and hosted in the Changchengian Chuanlinggou Formation of Mesoproterozoic, is an oldest depositional iron deposit characterized by oolitic and stromatolitic hematite and siderite. This thesis made an systematic study of its sedimentary, sedimentology, geochemistry, mineralogy and sequence stratigraphy. Based on above, the mechanism and background of biomineralization are discussed. There are four types of hematite ores including stromatolite, algal oolite, algal pisolite and oncolite. Based on detailed study on ore texture, the authors think both algal oolite and algal pisolite ores are organic texture ores, and related to the role of microorganisms. The process of blue-green algae and bacteria in the Xuanlong basin absorbing, adsorbing and sticking iron to build up stromatolite is the formation process of Xuanlong-type hematite deposit. Researches on ore-bearing series and ore geochemistry show that the enrichment of elements is closely related to the microorganism activities. Fe_2O_3 is enriched in dark laminations of stromatolite with much organic matter and SiO_2 in light laminations with detrital matters. The trace elements, especially biogenic elements, including V, P, Mo are enriched in ores but relatively low in country rocks. The paper also demonstrates on the sequence stratigraphy of hematite deposits and five sequences and twelve systems are divided. The characteristics of sequence stratigraphy show that the deposit-forming location has obviously selectivity and always exists under a transgressive setting. The oxygen isotope in hematite is about -2.2～5.7‰, which is similar to that of Hamlys iron formation of Australia but more negative than that of volcanic or hydrothermal iron deposits characterized by high positive values. The calculation by the result of oxygen isotope analysis shows that the temperature of ancient sea water was 48.53℃. The negative value of carbon isotope from siderite indicates its biogenic carbon source. Meanwhile, the occurrence of seismite in the ore-beds, which indicates the formation of hematite deposits is associated with frequent shock caused by structural movement such as distal volcano or ocean-bottom earthquake etc, show the occurrence of hematite deposits is eventual, not gradual. In shorts, Xuanlong-type hematite deposits were the result of interaction among geological setting of semi-isolated Xuanglong basin, favorable hot and humid climate condition, abundant iron source, microorganism such as algae and bateria as well as the fluctuation of the sea level.

广西六景泥盆系腕足壳体的微量元素组成及其对海水信息的保存

低镁方解石腕足化石壳体被广泛地应用于地质历史时期原始海洋地球化学组成的重建研究,其保存度的识别是该研究的一项重要内容。通常使用显微结构、阴极发光和微量元素含量等3 种方法验证其对原始地球化学信息的保存,微量元素含量的识别方法一直被置于较为次要的地位。我们对采自广西六景泥盆系腕足化石微量元素研究表明,其Fe 、Mn、Sr 分别为(12～2800) ×10 - 6 、(1～711) ×10 - 6和(243～1835) ×10 - 6 。上述3 种识别方法实质上都是微量元素的识别,其余两种识别方法只是微量元素的不同表现而已。通过氧同位素组成、Mn 和Sr/ Mn 对比,得知Mn 含量小于100 ×10 - 6 ,Sr/ Mn 值高于10的腕足化石壳体基本上保存完好。这一发现为利用腕足化石研究海水原始碳氧同位素提供了有力的判据。