天津蓟县硼矿床锰方硼石矿物的硼同位素研究

天津蓟县硼矿床是世界上唯一的沉积环境特殊的锰方硼石型硼矿床。矿床呈层状产于震旦系碳酸岩泥灰质岩系中 ,矿石呈鲕粒状或球粒状集合体 ,是成因条件极其特殊的矿床类型。含矿岩系为中元古界高于庄组沉积岩系 ,含矿岩性由下而上依次为含锰白云岩、页岩互层→含锰白云岩、泥硅质岩 ,夹锰方硼石矿层→含锰页岩、白云岩→厚层白云岩→薄层白云岩→厚层白云岩 ,锰方硼石矿体在矿层中呈断续相连的团块状或透镜状分布。硼矿物成分简单 ,只有锰方硼石一种矿物 ,锰方硼石矿体呈透镜状断续成层分布 ,东西延长达 30km。东部矿段以锰方硼石为主 ,向西部渐变为菱锰矿。矿石有块状和斑点状。块状矿石全部由球粒状锰方硼石集合体组成 ,w (B2 O3 ) >2 0 % ,最高可达 4 2 %以上。斑点状矿石中锰方硼石集中呈球粒状集合体分布于泥质白云岩中 ,w (B2 O3 ) <7%。首次研究了该硼矿床锰方硼石的硼同位素组成 ,δ11B值为 +6 7‰～ +14 9‰ ,均为正值 ,并且东部大峪矿段的硼同位素值低于西部柏树沟矿段的硼同位素值 ,表明该硼矿床的成矿元素属于海水来源。由于锰方硼石的微量元素组成难以与蒸发岩比较 ,且富含F、Ba、Sn热液富集的元素和Co、Ni、Cr、Ti基性岩浆岩元素以及与Fe、Mn大洋结核有关的元素组分 ,因此锰方硼石应属于     

锚注支护机理及参数优化研究

对锚注支护机理进行了分析，得出巷道锚注支护可改善锚杆，裂隙面及围岩的力学性能，减小围岩塑性区及巷道位移，提高围岩的稳定性，并运用正交设计方法对锚注支护参数进行优化，确定了主要影响因素，提出了可供参考的支护方案。     

Products and mechanism of the reaction of NO3 with selected acyclic monoalkenes

The gas-phase reactions of NO₃ with 2-methyl-2-butene, isobutene,trans-butene, 1-butene and propene, were investigated in a flow-tube at room temperature. Experiments were performed in the pressure range 1–1000 mbar in synthetic air as well as at a total pressure of 800 mbar with varying concentrations of oxygen in nitrogen.The main products found were oxiranes, nitroxy-carbonyl compounds (ketonitrates) and ketones or aldehydes. The product distribution was a function of pressure. In each case, in synthetic air, the oxirane yield increased with decreasing total pressure up to a value of about 100% at pressures less than 1 mbar.It was concluded that oxirane is a product of the excited adduct radical formed in the electrophilic addition of NO₃ to the double bond. Experiments with very low partial pressures of oxygen showed that the quenched adduct radicals also produce the corresponding oxirane.Under tropospheric conditions (1000 mbar synthetic air) the following yields of the corresponding oxiranes were found: 2-methyl-2-butene 9%, isobutene 7%,trans-butene 12%, 1-butene 18%, propene 28%. In the case oftrans-butene the total oxirane yield consists of 72%trans- and 28%cis-isomer.Dedicated to Professor Wolfgang Rolle on the occasion of his 60th birthday.     

Strontium in rivers of the Baltic Basin

The rivers in the Baltic Basin drain a mixture of bedrocks ranging from Mesozoic-Paleozoic sediments in the south to Proterozoic-Archean intrusives in the north. The rivers in the sedimentary basin in the south have high concentrations of Sr, in the interval 100–500 µg l^–1 while the⁸⁷Sr/⁸⁶Sr ratio is close to that of seawater, i.e. 0.71. The northern rivers in the Precambrian shield area on the other hand have low Sr concentrations of 15–50 µg l^–1 with high⁸⁷Sr/⁸⁶Sr ratios of about to 0.73 (0.721–0.745). The riverine input of dissolved Sr to the brackish Baltic Sea approaches 60 tons year^–1, with a weighted mean concentration approaching 130 µg l^–1 and a weighted mean⁸⁷Sr/⁸⁶Sr ratio close to 0.712. Although the sedimentary area in the south supplies only about 43% of the total river discharge, it gives about 88% of the total Sr input. Because of this and the strong regional riverine variation in⁸⁷Sr/⁸⁶Sr ratio, Sr and its isotopes seem to be a convenient tool to unveil mixing relations of water masses in the northern Baltic Sea, provided high resolution analyses are applied. For an overall characterization of water mixing in the Baltic Sea, the Nd system will be superior to that of Sr.     

天山北坡经济带固定资产投资特征及其对城镇集聚的影响

 在研究天山北坡经济带2000-2009年固定资产投资和城镇集聚基本特征基础之上,采用主成分分析法和面板数据回归模型,定量分析了固定资产投资对该地区城镇集聚的影响和作用机制。结果表明：（1）天山北坡经济带全社会固定资产投资在各县市分布相对集中于区域中心城市,呈现明显的“序位-规模”分布,具有行政区经济的特点,政府主导度与投资集中度成反向关系;（2）天山北坡经济带的城镇集聚过程首先以经济集聚和土地的非农化过程为主,其次是城镇人口的集聚,最后是社会生活水平的提高;（3）以固定资产投资为代表的政府行政力是推动天山北坡经济带城镇集聚的重要力量之一,其对行政级别越高,工业化水平越高城镇的集聚作用更强;（4）不同时期天山北坡经济带固定资产投资对城镇集聚的作用效应并不相同,初期投资主要促进城镇人口和空间规模的扩大,对城镇经济集聚作用较小;末期投资对城镇经济集聚、人口与空间规模均具有明显的促进作用,对社会人均基础设施及生活水平有较小的负作用。     

Social learning towards a more adaptive paradigm? Reducing flood risk in Kristianstad municipality,Sweden

Social learning is often treated as an intervention, a designed process facilitated or even initiated by a third party. We investigated how a social learning process emerged spontaneously from inside Kristianstad, one of the most flood-prone municipalities in Sweden. Twenty key persons were interviewed over 8 years, many of them several times, to assess the process. A small action oriented group of technical professionals perceived the flood risk and were key drivers providing strategic innovative capacity. We identified the process attributes that fostered the learning, the knowledge generated and other learning outcomes adapting a model by Schusler et al. (2003). Despite some elements of double loop learning, this process was not able to change the prevailing stationary principle/paradigm, feeling safe behind the embankments and continuing building on low lying land. We argue that building resilience and adaptive capacity would require a mind shift to a paradigm of flood proofing/living with floods and preparing for the unexpected, acknowledging that water cannot be controlled at a certain level. We conclude that knowledge development is inhibited by the Swedish decentralisation approach and we call for a multilevel learning strategy including learning from international experience and emphasising more active coordination at the national level.     

Evaluating preprocessing methods of digital elevation models for hydrological modelling

With the introduction of high‐resolution digital elevation models, it is possible to use digital terrain analysis to extract small streams. In order to map streams correctly, it is necessary to remove errors and artificial sinks in the digital elevation models. This step is known as preprocessing and will allow water to move across a digital landscape. However, new challenges are introduced with increasing resolution because the effect of anthropogenic artefacts such as road embankments and bridges increases with increased resolution. These are problematic during the preprocessing step because they are elevated above the surrounding landscape and act as artificial dams. The aims of this study were to evaluate the effect of different preprocessing methods such as breaching and filling on digital elevation models with different resolutions (2, 4, 8, and 16 m) and to evaluate which preprocessing methods most accurately route water across road impoundments at actual culvert locations. A unique dataset with over 30,000 field‐mapped road culverts was used to assess the accuracy of stream networks derived from digital elevation models using different preprocessing methods. Our results showed that the accuracy of stream networks increases with increasing resolution. Breaching created the most accurate stream networks on all resolutions, whereas filling was the least accurate. Burning streams from the topographic map across roads from the topographic map increased the accuracy for all methods and resolutions. In addition, the impact in terms of change in area and absolute volume between original and preprocessed digital elevation models was smaller for breaching than for filling. With the appropriate methods, it is possible to extract accurate stream networks from high‐resolution digital elevation models with extensive road networks, thus providing forest managers with stream networks that can be used when planning operations in wet areas or areas near streams to prevent rutting, sediment transport, and mercury export.     

The sediment-fill of Pago Pago Bay (Tutuila Island,American Samoa): New insights on the sediment record of past tsunamis

Extensive bathymetric and two-dimensional seismic surveys have been carried out and cores collected in Pago Pago Bay (Tutuila, American Samoa) in order to describe and gain a better understanding of the sediment fill of the bay, which was affected by the 2009 South Pacific Tsunami. Eight sedimentary units were identified over the volcanic bedrock. The basal transgressive unit displays retrograding onlaps towards the shore, whereas the overlying seven aggradational layers alternate between four draping units and three pinching out seaward units. ‘Core to seismic’ correlation reveals that draping units are composed of homogeneous silts, while pinching out units are dominated by very coarse coral fragments showing fresh cuts, mixed with Halimeda plates. The basal unit is attributed to transgressive sedimentation in response to flooding of the bay after the last glacial maximum, followed by the upper aggradational units corresponding to highstand sedimentation. The changeovers in these upper units indicate an alternation between low-energy silt units and high-energy coral debris units interpreted as tsunami-induced deposits. The ¹⁴C dating reveals that high-energy sedimentation units can last up to approximately 2000 years while low-energy sedimentation units can last up to approximately 1000 years. This alternation, deposited during the last highstand, may be explained by cycles of tectonic activity and quiescence of the Tonga Trench subduction, which is the main source of tsunamigenic earthquakes impacting the Samoan archipelago. In the uppermost silt unit, only the geochemical signature of the terrestrial input of the 2009 SPT backwash deposits was detected between 7 cm and 9 cm depth. Hence, Pago Pago Bay offers a unique sediment record of Holocene bay-fill under the impact of past tsunamis intermittently during the last 7000 years.     

On the location of energy release and temperature profiles along coronal loops

Several mechanisms have been suggested to contribute to the heating of the solar corona, each of which deposits energy along coronal loops in a characteristic way. To compare the theoretical models with observations one has to derive observable quantities from the models. One such parameter is the temperature profile along a loop. Here numerical experiments of flux braiding are used to provide the spatial distribution of energy deposition along a loop. It is found that braiding produces a heat distribution along the loop which has slight peaks near the footpoints and summit and whose magnitude depends on the driving time. Using different examples of the heat deposition, the temperature profiles along the loop are determined assuming a steady state. Along with this, different methods for providing average temperature profiles from the time-series have been investigated. These give summit temperatures within approximately 10% of each other. The distribution of the heating has a significant impact on both the summit temperature and the temperature distribution along the loop. In each case the ratio between the heat deposited and radiation provides a scaling for the summit temperature.     

Predicted wavelengths of coronal transitions in the configurations 3s 23p 2, 3s 23p 3 and 3s 23p 4

The level intervals in the ground configurations 3s ²3p ^k(k = 2, 3, 4) have been studied through the isoelectronic sequences up to Ni. Semiempirical expressions for the parameters F ₂(pp) and _p, are derived from observed data and the intervals are recalculated from interpolated or extrapolated values of the parameters. As a result, predicted wavelengths of magnetic-dipole transitions within the configurations are obtained with an estimated uncertainty of one or two Å.