卟啉类化合物在光度分析中的应用新进展

卟啉类化合物应用于光度分析灵敏度高、方法简便,并能测定多种元素。本文就1987年以来的国内文献作一综述(1987年前见文献)。从中可见,卟啉在光度法同时测定多组分、荧光分析、离子交换树脂比色法、光度法与HPLC联用以及作为生物模拟酶应用于光度分析等方面的潜力仍有待挖掘。     

Groundwater regime and calculation of yield response in North China Plain: a case study of Luancheng County in Hebei Province

The groundwater table has been declining at a rate of 0.65 m/yr in Luancheng County since large scale groundwater extraction carried out in the 1960s. The drop of precipitation, substantial increase in agricultural output, variations of crop planting structure and construction of water conservancy projects in the headwater area all tie up with the decline of the groundwater table. On the basis of analyzing the hydrogeological conditions and the water resources utilization of Luancheng County, a three-dimensional groundwater flow model was developed to simulate the county’s groundwater flow through finite-difference method using Visual Modflow software. We divide the research field into four parts after analyzing the hydrogeological condition. Based on parameter calibration and adjustment using measured data, the hydraulic conductivity and specific yield were simulated. Using the calibrated model, we analyze the agricultural water saving potentiality and its influence on the groundwater. The results are as follows: (1) if we decrease the amount of water extracted by 0.14xl0⁸ m³, the average groundwater table of the five observation wells in December will rise by 0.33 m; (2) if we decrease the water by 0.29x 10⁸m³, the average groundwater table of the five observation wells in December will rise by 0.64 m; and (3) if we increase the water by 0.29 x 10⁸m³, the average groundwater table of the five observation wells in December will decline by 0.45 m. So we can draw a conclusion that controlling the agricultural water use is an important way to prevent the decline of groundwater table.     

基于GIS的梅里雪山国家公园土壤侵蚀敏感性情景分析

运用GIS-IDRISI软件,在其空间分析模块支持下,结合植被、土壤和DEM数据建立了一个土壤侵蚀功能模型,并在3种不同植被状况下(1.现有植被;2.植被遭受严重破坏;3.植被得以良好保护和恢复),利用此模型对梅里雪山国家公园的土壤侵蚀状况进行情景分析.结果表明:在梅里雪山国家公园内,土壤侵蚀极敏感和高度敏感区,主要分布于高海拔的高山区域和低海拔的澜沧江河谷区,而中度敏感、轻度敏感和不敏感区主要分布于中间海拔区域.研究区现有植被得到了当地藏族居民的较好保护,但如果该区域的植被受到严重破坏,如情景2所示,那么土壤侵蚀极敏感、高度敏感和中度敏感区面积将大量增加,相反,轻度敏感和不敏感区的面积将大量减少,尤其是不敏感区将几乎全部消失.所以梅里雪山国家公园当前的首要任务为保护好当地的植被和各生态系统.     

Climatic drivers of tree growth at tree line in Southwest Yukon change over time and vary between landscapes

Growth of trees at their altitudinal and latitudinal range limits is expected to increase as climate warms, but trees often exhibit unexplained spatial and temporal variation in climate-growth responses, particularly in alpine regions. Until this variability is explained, predictions of future tree growth are unlikely to be accurate. We sampled Picea glauca (white spruce) growing at forest and tree line on north and south aspects in two mountain ranges of southwest Yukon to determine how and why ring-width patterns vary between topographic settings, and over time. We used multivariate statistical analysis to characterize variation in ring-width patterns between topographic factors and time periods, and calculated correlations between ring-width indices and climate variables to explain this variation. Ring-width patterns varied more between mountain ranges than elevations or aspects, particularly in recent decades when ring-widths increased in one mountain range but not the other. Growth responses to summer temperature were notably weaker during warmer time periods, but growth was not positively correlated to summer precipitation, suggesting trees may not be suffering from temperature-induced drought stress. Rather, ring-width indices began responding positively to spring snow depth after 1976. We conclude that tree growth is unlikely to increase in synchrony with rising air temperatures across subarctic tree lines in southwest Yukon. Instead, they may decline in areas that are prone to thin snowpacks or rapid spring runoff due to the negative influence warming springs will have on snow depth and, consequently, early growing season soil moisture.     

基于遥感增强嵌套模型红树林带水沙环境对码头建设的响应研究

南海北部湾铁山港码头建设期间,邻近区域红树林带植株出现受损死亡现象。本研究构建基于遥感增强包含红树林潮间带的海湾水沙嵌套模型,评估码头建设对红树林带潮流、泥沙输移及冲淤的影响。结果表明：海湾水沙嵌套模型可充分利用南海海流模拟信息,且精细化模拟了工程建设附近海域泥沙输移规律。采用全球地表水覆盖几率遥感反演数据与当地潮位的信息融合技术,为红树林带水沙模拟提供了可靠地形信息。码头建设主要影响红树林带南部潮流,涨急时流速减小,落急时部分潮沟通道流速增大。当进港方案更改为过水钢栈桥,红树林带东南部流速略有增加。码头施工期,红树林带69%～72%范围的悬浮泥沙浓度增量介于20～50 mg/L之间。码头建设前,红树林带泥沙平均冲淤量为0.27 cm/a;进港方案分别为不过水通道和过水钢栈桥,码头建设后红树林带淤积量增加的面积占比分别为96.6%和89.3%,平均冲淤量分别为0.45 cm/a和0.36 cm/a。过水钢栈桥替换不过水通道,红树林带冲淤增量下降了50.0%。研究结论可为潮间带水沙环境模拟和红树林带保护决策提供科学依据。     

南沙群岛海域构造地层及构造运动

根据对“实验2”号调查船1987—1991年测得的反射地震剖面的解释,论述了南沙群岛海域的构造层划分、时代属性与分布发育特征。提出本区自白垩纪中期以来发生过两次重大的构造运动,形成两个裂谷作用构造旋回。     

从海岸滩涂变迁看上海滩涂土地资源的利用

海岸滩涂是上海市重要的土地后备资源,其在空间与时间上的表现又不尽相同。利用遥感技术可以分析与调查滩涂土地资源利用的分布与变化状况,为科学规划、合理保护和科学论证滩涂资源提供重要依据。该文针对上海市滩涂土地资源利用现状遥感调查,阐述了滩涂遥感信息的提取过程,讨论了其分布结构、多年变化情况,同时结合上海市可持续发展战略,对海岸滩涂开发利用提出了意见。     

Aftershock activity of Bhuj earthquake of january 26th, 2001

Following a large-sized Bhuj earthquake (M _s = 7.6) of January 26th, 2001, a small aperture 4-station temporary local network was deployed, in the epicentral area, for a period of about three weeks and resulted in the recording of more than 1800 aftershocks (-0.07 ≤M _L <5.0). Preliminary locations of epicenters of 297 aftershocks (2.0 ≤M _L <5.0) have brought out a dense cluster of aftershock activity, the center of which falls 20 km NW of Bhachau. Epicentral locations of after-shocks encompass a surface area of about 50 × 40 km² that seems to indicate the surface projection of the rupture area associated with the earthquake. The distribution of aftershock activity above magnitude 3, shows that aftershocks are nonuniformly distributed and are aligned in the north, northwest and northeast directions. The epicenter of the mainshock falls on the southern edge of the delineated zone of aftershock activity and the maximum clustering of activity occurs in close proximity of the mainshock. Well-constrained focal depths of 122 aftershocks show that 89% of the aftershocks occurred at depths ranging between 6 and 25 km and only 7% and 4% aftershocks occur at depths less than 5 and more than 25 km respectively. The Gutenberg-Richter (GR) relationship, logN = 4.52 - 0.89M_L, is fitted to the aftershock data (1.0<-M _L<5.0) and theb-value of 0.89 has been estimated for the aftershock activity.     

The potential use of OH-defects in enstatite as geobarometer

In this study, single crystals of pure enstatite (Mg₂Si₂O₆) were synthesised under water-saturated conditions at 4 and 8 GPa and 1,150°C with variable silica activity, leading to phase assemblages enstatite + forsterite, enstatite or enstatite + coesite. Run products were investigated using an FTIR spectrometer equipped with a focal plane array detector enabling IR imaging with a lateral pixel resolution of 2.7 μm. IR spectra within the OH-absorption region show two different groups of absorption bands: group 1 (wavenumbers at 3,592 and 3,687 cm^?1) shows strongest absorptions for E||n _β, whereas group 2 (wavenumbers at 3,067 and 3,362 cm^?1) shows strongest absorptions for E||n _γ. The groups are related to different defect types, group 1 to tetrahedral defects (T-site vacancies) and group 2 to octahedral defects (M-site vacancies). The intensity ratio of the bands within one group (i.e. A ₃₀₆₇/A ₃₃₆₂ and A ₃₅₉₂/A ₃₆₈₇) and the intensity ratio of E||n _γ and E||n _α in group 2 bands remain constant within error. In contrast, the intensity ratio of group 2 to group 1 absorption bands [e.g. (A ₃₃₆₂)/(A ₃₆₈₇)] is sensitive to the SiO₂ activity and pressure. On the basis of the results of this and previous studies, a barometer for pure orthoenstatite coexisting with forsterite can be formulated:\( P\,[{\text{GPa}}] = 1.056 + \sqrt {{\frac{{1.025 - A_{{\left( {3362} \right)/\left[ {(3362) + (3687)} \right]}} }}{0.009}}} , \) where A ₍₃₃₆₂₎ and A ₍₃₆₈₇₎ are the integral absorbances of the component E||n _γ of the absorption bands at 3,362 cm^?1 and the component E||n _β of the absorption band at 3,687 cm^?1, respectively.     

Variation in DOC and trace metal concentration along the heavily urbanized basin in Kathmandu Valley,Nepal

Water samples were analyzed for DOC and trace metals from Bagmati River within Kathmandu valley, Nepal, to understand the variation trends of DOC and trace metals and their relationship along the drainage network. The variability in organic matter and wastewater input within the Bagmati drainage basin appeared to control DOC and most of the trace metal concentration. The large input of organic matter and wastewater creates anoxic condition by consuming dissolved oxygen and releasing higher concentrations of DOC, trace elements such as nickel, arsenic, barium, cadmium, and copper with downstream distance. Concentrations of DOC and trace metals like barium and zinc showed strong relationships with human population density and suggest that human activities have strong control on these parameters along the drainage network. The DOC and most of the trace metal concentration increased with downstream distance and appeared to be directly associated with human activities. The variation trends of most of the trace metals appeared to be the same; however, concentration varied widely. Inputs of organic matter and wastewater due to human activities appeared directly to be associated for the variation of DOC and trace metals along the Bagmati drainage network within Kathmandu valley.