H_2O_2增效TiO_2/凹凸棒石光催化体系降解亚甲基蓝

以钛酸四丁酯为前驱体,天然凹凸棒石为载体,采用溶胶凝胶法制备了TiO_2/凹凸棒石复合光催化剂,并用XRD、TEM对其进行表征.以亚甲基蓝染料为模拟污染物,采用300 W汞灯为紫外光源,以光催化实验来评价该催化剂的活性,并研究了H_2O_2的引入对光催化活性的影响.实验结果表明,H_2O_2能显著提高染料的脱色效率:亚甲基蓝的初始浓度为50 mg/L,催化体系为2 mmol/L H_2O_2+0.5 g/L TiO_2/凹凸棒石+UV(紫外线),光催化10 min后其脱色率为95%,相对于单独的0.5 g/L TiO_2/凹凸棒石+UV催化体系,其脱色率提高了约50%.全波段扫描显示,加入H_2O_2后,亚甲基蓝在290 nm对应的苯环吸收蜂急剧下降,665 nm对应的最大吸收峰则近乎消失,且没有新的吸收峰产生.     

下击暴流实例分析

通过实地灾情调查,本文提供了一个证据较为充分、说服力较强的下击暴流实例,加深了人们对下击暴流的感性认识。实践证明,在观测密度(时间和空间上)远不能满足中小尺度分析要求、探测手段受到很大限制的情况下,用实地灾情调查和地面拍照的办法进行下击暴流这类中小尺度系统的分析是可行的。     

基于RAMS/CFORS Ⅱ模式一次低空核试验放射性烟云扩散的数值模拟

采用RAMS／CFORS Ⅱ模式模拟了一次低空核试验烟云的传输和沉降过程。CFORS Ⅱ模式是在RAMS／CFORS模式的基础上开发的,可用于对核试验放射性烟云长距离输送和沉降过程的模拟研究。模拟表明：对流层中低层的低压槽系统对本次低空核试验烟云的水平传输和垂直扩散起着重要的影响作用;烟云的长距离传输速度呈现出随高度递减而减小的趋势,在6000m以上,烟云在爆后48h即东移入海,6000m以下,烟云在中国大陆的扩散和沉降维持了5d以上;爆后2天内以大粒子沉降为主,其后以小粒子沉降为主,小粒子的放射性远小于大粒子,在爆后第4天,放射性沉降就减小了3个量级,而小粒子的沉降范围是大粒子的5倍以上。通过模拟和观测对比表明,模拟结果基本符合实际烟云的传输和沉降态势。     

2008年1月一次强雨雪过程的诊断分析

采用NCEP1°×1°客观再分析资料和常规观测资料,对2008年1月25—29日发生在长江中下游地区的强雨雪过程进行诊断分析,结果表明,低空急流与强雨雪有着密切关系,强雨雪的发生需具备一定的温度条件以及水汽场与动力场的耦合机制。对强雨雪过程的湿Q矢量诊断分析表明,700hPa湿Q矢量辐合区以及850hPa锋生函数正值区与强雨雪区对应较好,对雨雪天气的发生有着很好的指示意义。湿位涡特征分析表明,此次强雨雪过程发生在层结稳定的大气中且垂直涡度发展较强。     

基于RIA和SOA的分布式WebGIS研究

基于当前流行的RIA平台和SOA体系,以分布式WebGIS为研究对象,探讨RIA/Services架构的分布式WebGIS开发方式,并以Silverlight和ArcGIS Server为平台阐述实践方案,开发的实验系统提高了WebGIS的表现力与交互性,同时降低了开发的复杂性、缩短了产品生产周期,具有一定的理论和现实意义。     

太湖、洞庭湖野生青虾肌肉中有机氯农药的气相色谱-质谱法测定

使用气相色谱质谱技术测定了青虾肌肉组织中的8种有机氯农药.包括六氯苯、氯丹、滴滴涕(ΣDDTs)、艾氏剂、狄氏剂、异狄氏剂、七氯和灭蚁灵,对太湖和洞庭湖15个点位29组野士青虾样品的测定结果显示,青虾肌肉组织内残留的有机氯农药主要是六氯苯和滴滴涕,六氯苯含量为nd-13.2μg/kg(湿重),滴滴涕含量为0.790-5.82μg/kg(湿重),洞庭湖青虾肌肉中有机氯农药的含量略高于太湖青虾,两湖青虾肌肉残留有机氯农药在枯水期时的含量多数大于丰水期时的含量.     

Accumulation by securitization: Commercial poaching,neoliberal conservation,and the creation of new wildlife frontiers

Part of a broader interest in the escalating securitization of conservation practice, scholars are beginning to take note of an emerging relationship between conservation–securitization, capital accumulation, and dispossession. We develop the concept of accumulation by securitization to better grasp this trend, positioning it in the critical literatures on neoliberal conservation, green grabbing, and conservation-security. The concept captures the ways in which capital accumulation, often tied to land and resource enclosure, is enabled by practices and logics of security. Security logics, moreover, increasingly provoke the dispossession of vulnerable communities, thereby enabling accumulation. We ground the concept by turning to the Greater Lebombo Conservancy (GLC) in the Mozambican borderlands. This is a new privately-held conservancy built as a securitized buffer zone to obstruct the movement of commercial rhino poachers into South Africa’s adjacent Kruger National Park. We show how wildlife tourism-related accumulation here is enabled by, and in some ways contingent upon, the GLC’s success in curbing poaching incursions, and, relatedly, how security concerns become the grounds upon which resident communities are displaced. In terms of the latter, we suggest security provides a troubling, depoliticized alibi for dispossession. Like broader neoliberal conservation and green grabbing, we illustrate how accumulation by securitization plays out within complex new networks of state and private actors. Yet these significantly expand to include including security actors and others motivated by security concerns.     

Geochemical and isotopic characterization of trace fossil infillings: New insights on tracemaker activity after the K/Pg impact event

Geochemical and isotopic analyses of the Cretaceous–Paleogene (K/Pg) boundary deposits were conducted at the Caravaca section (External Subbetic, southeast of Spain) in order to evaluate the recovery of the macrobenthic tracemaker community and the bioturbational disturbance. Samples from the infilling material of several lower Danian dark-colored trace fossils (Chondrites, Planolites, Thalassinoides and Zoophycos) located in the uppermost 8-cm of the light upper Maastrichtian strata, as well as samples from the host sedimentary rock of these trace fossils, were analyzed and compared with data from the lower Danian deposits. The values of element ratios indicative of extraterrestrial contamination (Cr/Al, Co/Al and Ni/Al) are higher in the infilling trace fossil material than in the upper Maastrichtian and lower Danian deposits, which suggests a contribution of the ejecta layer. Regarding the isotope composition, the δ¹³C values are lower in the infilling material than in the Maastrichtian host sedimentary rocks surrounding the traces, while the δ¹⁸O are higher in the infilling material. The geochemical and isotopic compositions of the infilling material evidence the unconsolidated character of the sediment, including the red boundary layer. Softground conditions confirm a relatively rapid recovery by the macrobenthic tracemaker community, starting a few millimeters above the K/Pg boundary layer. The mixture of the infilling material of the trace fossils moreover reveals a significant macrobenthic tracemaker activity affecting K–Pg boundary transition sediments that may have significantly altered original signatures.     

A note on “Origin of components in Chilean thermal waters” by

Risacher et al. (2011) have presented voluminous data on thermal waters of Chile that is quite appreciable; however, their work still falls short on several counts. The most notable shortcoming of the work is the presentation and treatment of data. The interpretations are based on questionable premises (viz., extent of seawater intrusion) and considerations (viz., using average chemical composition of rock types for geochemical modeling, considering volcanic rocks as the only rock type in contact with the geothermal fluids) and assumptions not always substantiated by facts (with proper references) could have been corroborated. Use of Cl/Br ratio for discrimination purpose is unconvincing, considering the uncertainty in the measurement of low (<1 mg/L) Br concentration.     

Hydrogen sulfide measurements in air by passive/diffusive samplers and high-frequency analyzer: A critical comparison

In this study, hydrogen sulfide (H₂S) measurements in air carried out using (a) passive/diffusive samplers (Radiello^® traps) and (b) a high-frequency (60 s) real-time analyzer (Thermo^® 450i) were compared in order to evaluate advantages and limitations of the two techniques. Four different sites in urban environments (Florence, Italy) and two volcanic areas characterized by intense degassing of H₂S-rich fluids (Campi Flegrei and Vulcano Island, Italy) were selected for such measurements. The concentrations of H₂S generally varied over 5 orders of magnitude (from 10⁻¹–10³ μg/m³), the H₂S values measured with the Radiello^® traps (H₂S_R) being significantly higher than the average values measured by the Thermo^® 450i during the trap exposure (H₂S_Ta), especially when H₂S was <30 μg/m³. To test the reproducibility of the Radiello^® traps, 8 passive/diffusive samplers were contemporaneously deployed within an 0.2 m² area in an H₂S-contaminated site at Mt. Amiata (Tuscany, Italy), revealing that the precision of the H₂S_R values was ±49%. This large uncertainty, whose cause was not recognizable, is to be added to that related to the environmental conditions (wind speed and direction, humidity, temperature), which are known to strongly affect passive measurements. The Thermo^® 450i analyzer measurements highlighted the occurrence of short-term temporal variations of the H₂S concentrations, with peak values (up to 5732 μg/m³) potentially harmful to the human health. The Radiello^® traps were not able to detect such temporal variability due to their large exposure time. The disagreement between the H₂S_R and H₂S_Ta values poses severe concerns for the selection of an appropriate methodological approach aimed to provide an accurate measurement of this highly toxic air pollutant in compliance with the WHO air quality guidelines. Although passive samplers may offer the opportunity to carry out low-cost preliminary surveys, the use of the high-frequency H₂S analyzer is preferred when an accurate assessment of air quality is required. In fact, the latter provides precise real-time measurements for a reliable estimation of the effective exposure to hazardous H₂S concentrations, giving insights into the mechanisms regulating the dispersion of this air pollutant in relation to the meteorological parameters.