Characterizing aquatic sediment-oil aggregates using in situ instruments

The effects of emulsified crude oil and salinity (15, 30 per thousand ) on the steady state aggregate volume distributions and fractal dimensions were determined for a range of mean velocity gradients, (G(m) =5-50 s(-1)). Aggregation was performed in a 40-L cylindrical tank with a 4-blade paddle mixer. Three-dimensional fractal dimensions (D3) and volume distributions were determined using a procedure integrating data from an electrozone and an in situ light scattering instrument. Two-dimensional fractal dimensions (D2) and derived volume distributions were determined using a recently developed submersible flow cytometer equipped with a digital camera and image analysis software. For latex beads or emulsified crude oil systems, the above listed instruments yielded consistent size distributions and fractal dimensions (D2=1.92 +/- 0.16, D3=2.94 +/- 0.12). Mean volume aggregate diameters determined using the FlowCAM were consistently larger that those determined using the LISST-100 or Coulter Multisizer due to aggregate orientations during measurements. With increasing G(m) values, all colloidal aggregates showed increasing D3 values due to reduced aggregate length. Because of the compactness of all the aggregates (D3 >2), D2 values remained constant at 2. Neither salinity nor sediment type significantly affected D2 values calculated for sediment-crude oil aggregates. However, clay-oil aggregates showed higher D3 values than clay aggregates. This suggests that colloidal oil and mixing shear are the more dominant factors influencing aggregate morphology in nearshore waters. Overall, the data suggests that the analysis methods provide consistent size distribution results. However, because of the shear and salinity of coastal waters, resulting aggregates are too compact to estimate their D3 values using image analysis alone.     

Science, policy and the management of sewage materials. The New York City experience

Development of national policy on sewage sludge management is a classic example of incremental policy formulation [Fiorino, D.J. 1995. Making Environmental Policy. University of California Press. Berkeley, CA. p. 269]. Consequently, policy has developed piecemeal, and results are, in some ways, different than intended. Land application of sewage sludge has not been a panacea. Many of the same types of policy are now being raised about it. We demonstrate this by examining the management of sewage materials by New York City from near the turn of the 20th century, when ocean dumping was viewed as a means to alleviate some of the gross pollution in New York Harbor, to when ocean dumping was banned, and thence to the present when sludge is applied to land as "biosolids." Lessons learned during this long, sometimes contentious history can be applied to present situations--specifically not understanding the long-term consequences of land-based reuse and disposal technologies.     

重组胎盘生长因子对大鼠急性心肌梗死后细胞凋亡的影响

目的 研究重组胎盘生长因子（recombinant placental growth factor,rPlGF）对大鼠急性心肌梗死后心肌细胞凋亡的影响并探讨其可能的作用机制。方法 采用结扎冠状动脉的方法建立大鼠急性心肌梗死模型,取40只模型大鼠随机分为模型组和rPlGF治疗组,并设假手术组,尾静脉注射给药。4周后,通过高频率超生影像系统检测舒张末期左心室内径（LVIDd）和收缩末期左心室内径（LVIDs）、短轴缩短率（FS）、射血分数（EF）、每搏排出量（SV）;TTC染色法计算心肌梗死面积,TUNEL法观察心肌细胞凋亡状况,RT-PCR法测定心肌组织bcl-2 mRNA、Bax mRNA表达,Western blot法测定心肌组织caspase-3、NF-κB蛋白表达;比色法测定心肌组织中抗氧化酶活性和丙二醛（MDA）含量。结果 与模型组比较发现经rPlGF 治疗能够显著降低急性心肌梗死大鼠LVIDd和LVIDs,提高FS、EF和SV;降低心肌组织梗死面积,显著降低心肌细胞凋亡指数（apoptosis index,AI）、明显改善心肌细胞凋亡状况,上调bcl-2 mRNA表达并下调Bax mRNA表达、显著提高bcl-2/Bax比值,显著降低caspase-3、NF-κB蛋白表达量,显著提高抗氧化酶（SOD、CAT）活性并显著降低MDA含量,差异均具有统计学意义（P<0.05,P<0.01）。结论 rPlGF具有抑制大鼠急性心肌梗死后细胞凋亡的作用,其机制可能与rPlGF改善心功能、调节凋亡相关基因蛋白表达以及抑制氧化应激损伤有关。     

Reflectance spectroscopy of ferric sulfate-bearing montmorillonites as Mars soil analog materials

Spectroscopic analyses have shown that smectites enhanced in the laboratory with additional ferric species exhibit important similarities to those of the soils on Mars. Ferrihydrite in these chemically treated smectites has features in the visible to near-infrared region that resemble the energies and band strengths of features in reflectance spectra observed for several bright regions on Mars. New samples have been prepared with sulfate as well, because S was found by Viking to be a major component in the surface material on Mars. A suite of ferrihydrite-bearing and ferric sulfate-bearing montmorillonites, prepared with variable Fe3+ and S concentrations and variable pH conditions, has been analyzed using reflectance spectroscopy in the visible and infrared regions, M?ssbauer spectroscopy at room temperature and 4 K, differential thermal analysis, and X-ray diffraction. These analyses support the formation of ferrihydrite of variable crystallinity in the ferrihydrite-bearing montmorillonites and a combination of schwertmannite and ferrihydrite in the ferric sulfate-bearing montmorillonites. Small quantities of poorly crystalline or nanophase forms of other ferric materials may also be present in these samples. The chemical formation conditions of the ferrihydrite-bearing and ferric sulfate-bearing montmorillonites influence the character of the low temperature M?ssbauer sextets and the visible reflectance spectra. An absorption minimum is observed at 0.88-0.89 micrometers in spectra of the ferric sulfate-bearing samples, and at 0.89-0.92 micrometers in spectra of the ferrihydrate-bearing montmorillonites. M?ssbauer spectra of the ferric sulfate-bearing montmorillonites indicate variable concentrations of ferrihydrite and schwertmannite in the interlaminar spaces and along grain surfaces. Dehydration under reduced atmospheric pressure conditions induces a greater effect on the adsorbed and interlayer water in ferrihydrite-bearing montmorillonite than on the water in ferric sulfate-bearing montmorillonite. Reflectance spectra of ferric sulfate-bearing montmorillonite include a strong 3-micrometers band that is more resistant to dry atmospheric conditions than the 3-micrometers band in spectra of similarly prepared ferrihydrite-bearing montmorillonites.     

Meteorite organics in planetary environments: hydrothermal release, surface activity, and microbial utilization

Up to 50% of the organics in the Murchison meteorite, possibly including some of the polymer, is released in high temperature and pressure aqueous environments, to 350 degrees C and 250 bar, that simulate submarine volcanic, hydrothermal or impact-induced conditions. Meteorite organics of prebiotic significance, such as nonanoic acid, glycine, and pyrene survive the hydrothermal conditions. The released material is surface active with surface pressures up to 19.8 x 10(-3) N m-1, and exhibits an extended surface tension isotherm which suggests a mixture of amphiphilic components. One component, nonanoic acid, is shown to form vesicles. The materials extracted under mild conditions, at 120 degrees C, are nutrients for the humic acid bacterium Pseudomonas maltophilia and efficient nutrients for the oligotroph Flavobacterium oryzihabitans, demonstrating the capability of microorganisms to metabolize extraterrestrial organics.     

一种地名地理实体数据自动获取方法

以提高地名地理实体数据自动化生产程度为切入点,充分利用矢量基础地理框架数据成果,提出了一种地名地理实体数据自动获取方法。首先结合矢量基础地理框架数据的数据分布特点,制定了合理的地名地理实体数据自动提取策略;在此基础上,针对所提取的数据集存在重复地名、同一地名的地理实体数据存储分散或被动分割等问题,通过设计有效的地名匹配策略,对同一地名进行去除重复处理,在此基础上将对应的地名地理实体数据进行归并处理;最后,结合实体数据的组织特点,建立了适合于点、线、面、多点、多线、多面、几何集合等不同类型的地名地理实体数据重组方法,实现对地名地理实体数据的空间重组。实验表明,采用所提出的方法,不仅能有效地获取地名地理实体数据,满足地名工程建设需求;而且改变了传统的数据生产模式,充分利用了现有数据成果,避免了地名地理实体数据的重复建设。该方法的提出为地名相关工程建设中地名地理实体数据的生产、更新提供了一种新思路和新方法。     

社会资本的地理学研究进展

随着社会资本在促进民主、发展经济、健康身体、解决贫困等方面的作用逐渐被人们认知,社会资本吸引了众多学科的关注,地理学者也意识到社会资本对地理现象的解释作用,并结合具体问题开展了一些实证性研究,但由于在地理学中引入社会资本的研究历史较短,国内迄今尚缺乏系统性的梳理和研究架构的探讨。本文在研读近年来国内外相关文献的基础上,对基于空间尺度、地域性差异的社会资本研究,以及社会资本在经济地理、城市社会地理、健康地理等领域的研究进行梳理和总结,并从社会资本的地理学研究思路与框架、测量指标、以及研究领域的拓展等方面进行了展望,以期促进社会资本在地理学领域研究的深入展开,丰富社会资本的理论与实践。     

1300 micron continuum and C18O line mapping of giant molecular cloud cores. II. W3, NGC 2264, NGC 6334I, RHO Ophiuchi and S140

In this paper we present nearly simultaneous 1300 microns continuum and J = 2-1 C18O maps of the cores of five molecular clouds, W3, NGC 2264, NGC 6334I, rho Oph, and S140. The purpose of this experiment was to compare these two column density tracers. We find that dust continuum and C18O emission are equally effective tracers of column density in molecular cloud cores and give a good indication of cloud structure. When the maps are analyzed in terms of the quantity q = Q/[a rho RX(C18O)], we find that q does not vary by much more than an order of magnitude either within objects or from object to object, implying that nominal dust parameters of absorption efficiency, radius, and gas-to-dust ratio and CO abundance are on average correct in a variety of sources. We did detect source-to-source variations in q. This variation could be either in the dust-to-CO number density ratio or in grain parameters. These variations are not well correlated with total source luminosity, average or typical temperature, or total column density. The best example of this variation appears to be rho Oph where q is about a factor of 7 lower than is typically found. Our approach is analogous to the study of the A nu to CO ratio and is probably equivalent to extending this study to large A nu if the same grains are responsible for both optical opacity and far-infrared to millimeter-wave emission. There is no fundamental reason to expect A nu/NCO or q to be constant and, in fact, we have found that it is not constant in even a small source sample.     

固相萃取-气相色谱法测定海水中狄氏剂和多氯联苯

狄氏剂与多氯联苯均是海洋环境中毒性大、难降解的有机污染物,建立海水中狄氏剂与多氯联苯快速、灵敏、准确的检测方法,具有重要意义。本文采用聚苯乙烯/二乙烯基苯（Cleanert PS）固相萃取柱对海水样品中的狄氏剂与7种多氯联苯进行分离富集,建立了气相色谱-电子捕获检测器（GC-μECD）的分析方法。实验了萃取流速、洗脱液、水样盐度与pH等实验条件对萃取效率的影响,确定样品以5.0 mL/min的流速经Cleanert PS固相萃取柱富集,真空抽干后用5.0 mL丙酮洗脱,挥干洗脱液,用1.0 mL正己烷定容,在选定的色谱条件下进行分析。方法精密度（RSD）为0.9%~4.4%,与《海洋监测规范》GB 17378.4—2007的RSD指标相比,精密度良好;加标回收率为82.1%~123.9%。狄氏剂的检出限（0.0088 μg/L）低于文献的检出限（0.05 μg/L）,7种多氯联苯的检出限（0.0012~0.0067 μg/L）低于文献的检出限（0.147~0.289 μg/L）。该方法适合于海水中痕量狄氏剂与多氯联苯的快速分析,具有一定的实用价值。