Stability of Fe–As composites formed with As(V) and aged ferrihydrite

During the aging process, ferrihydrite was transformed into mineral mixtures composed of different proportions of ferrihydrite, goethite, lepidocrocite and hematite. Such a transformation may affect the fixed ability of arsenic. In this study, the stability of Fe-As composites formed with As(V) and the minerals aged for 0, 1, 4, 10 and 30 days of ferrihydrite were systematically examined, and the effects of molar of ratios Fe/As were also clarified using kinetic methods combined with multiple spectroscopic techniques. The results indicated that As(V) was rapidly adsorbed on minerals during the initial polymerization process, which delayed both the ferrihydrite conversion and the hematite formation. When the Fe/As molar ratio was 1.875 and 5.66, the As(V) adsorbed by ferrihydrite began to release after 6 hr and 12 hr, respectively. The corresponding release amounts of As(V) were 0.55 g/L and 0.07 g/L, and the adsorption rates were 92.43% and 97.50% at 60 days, respectively. However, the As(V) adsorbed by the transformation products aged for 30 days of ferrihydrite began to release after adsorbed 30 days. The corresponding release amounts of As(V) were 0.25 g/L and 0.03 g/L, and the adsorption rates were 84.23% and 92.18% after adsorbed 60 days, for the Fe/As=1.875 and 5.66, respectively. Overall, the combination of As(V) with ferrihydrite and aged products transformed from a thermodynamically metastable phase to a dynamically stable state within a certain duration. Moreover, the aging process of ferrihydrite reduced the sorption ability of arsenate by iron (hydr)oxide but enhanced the stability of the Fe-As composites.     

公众信任及水灾风险认知的区域对比

通过在长江流域不同区域开展问卷调查(获885份样本),统计、比较公众对社会减灾能力的信任态度及水灾风险认知状况,并探讨信任与认知之间的关系。结果显示,公众对社会减灾能力基本持信任态度,信任度依次为:灾害监测预报预警>政府应急>防灾工程能力,其中下游地区公众的信任度较高。公众对于水灾的风险感知普遍偏弱,尤其是下游地区公众对发生水灾、受灾可能性的评估偏低(小于25%)。公众对于区域减灾能力的信任主要受到受灾经历(如灾情损失、灾后救援等)的影响,区域本底的灾害风险高低导致公众水灾风险认知的差异。风险较高区域(上、中游)公众更愿意采取较多的、积极的具体防减灾措施。     

藻细胞不同生长阶段的海泡石凝聚除藻性能

对铜绿微囊藻(Microcystis aeruginosa 469)的4个不同生长阶段:延迟末期,对数中期,对数末期和衰老初期的表面疏水性(疏水分配法)和表面电性(Zeta电位)进行了测定,并利用0.2 g/L的海泡石进行了凝聚除藻性能实验.结果显示以上4个生长阶段的藻细胞表面疏水性平均为:64%, 48%, 58%和70%,而凝聚沉降60 min后的藻细胞去除效率为:97%, 87%, 81%和99%,表明藻细胞表面疏水性与粘土凝聚性能之间有较好的相关性(R＝0.7～0.8),但与表面电性的关系不大.M.A.469各个生长阶段的表面疏水性和凝聚性能的强弱顺序可依次确定为:衰老期>延迟期>对数增长期.     

环境雌激素对男性生育因子的破坏作用

本文介绍了环境雌激素多氯联苯(PCBs)和酞酸酯(PEs)对男性生育因子的破坏作用,以及PCBs和PEs对精液参数的作用机制．对生育和不育男性的精液参数间的差异、精液异雌激素和精液参数间的相关性,以及不同范畴的不育男性精液质量的分析表明,PCBs和PEs对无明显病原学的不育男性的精液质量可能有破坏作用．     

Reduced take-off ability in robins (Erithacus rubecula) due to migratory fuel load

Recent studies have shown that large fuel loads in small birds impair flying ability. This is the first study to show how migratory fuel load affects flying ability, such as velocity and height gained at take-off in a predator escape situation, in a medium-distance migrant, and whether they adjust their take-off according to predator attack angle. First-year robins (Erithacus rubecula) were subjected to simulated attacks from a model merlin (Falco columbarius), and take-off velocity and angle were analysed. Robins with a wing load of 0.19 g cm⁻² took off at a 39% lower angle than robins with a wing load of 0.13 g cm⁻², while velocity remained unaffected. The robins did not adjust their angle of ascent in accordance with the predator's angle of attack. Since many predators rely on surprise attacks, a difference in flight ability due to varying fuel loads found in migrating robins can be important for birds' chances of survival when actually attacked. Received: 28 October 1998 / Received in revised form: 12 January 1999 / Accepted: 30 January 1999     

显微镜法测定粉尘分散度存在的问题

通过对显微镜分辨力的分析,指出当前常用的用显微镜来测定粉尘分散度的方法在实际运用中存在的问题,希望粉尘分散度的测定方法能得到进一步的完善。     

关于新疆环境应急能力建设的探讨

阐述了新疆环境应急能力建设的重要性,对新疆环境应急现状中存在的问题进行了分析,提出了加强环境应急能力建设的几点建议。     

防空导弹武器系统伪装能力综合评价研究

针对防空导弹武器系统的暴露特征,采用层次分析法,建立了防空导弹武器系统伪装能力多层次综合评价指标体系和综合评价模型,采用模糊聚类分析法对数据进行处理,得出各评价对象的综合评价结果。最后通过算例,验证了该模型的有效性。     

飞行认知能力的测量方案设计及模型研究

为了对飞行员飞行认知能力水平提供评价依据,进行飞行认知能力测量方案设计。根据飞行员的驾驶特征以及操作行为提出6项测量指标,分别为空间定位能力、空间定向能力、空间想象能力、信息获取能力、信息加工能力和学习能力;根据测量指标和认知能力测试量表功能间的对应关系,设计包括6项认知测验的测量方案。随后开展测量并对结果进行分析,提取3个主因子分别命名为空间认知能力、信息管理能力和学习能力,从而建立起二阶多维度的认知能力结构模型。该模型可应用于飞行认知能力的测评工作。     

尾矿库地震液化机理及抗震评估指标体系研究

2008年"5.12"汶川大地震中,四川、陕西和甘肃三省尾矿库均受到不同程度的破坏和影响。本文针对四川汶川地震造成灾区尾矿库排洪系统失效,坝基沉降,坝体滑坡、垮塌、开裂等现状,对尾矿库地震溃坝机理进行了分析,研究了地震作用机理和地震液化的影响因素;在此基础上,建立起用于评估尾矿库抗震能力和地震溃坝可能性的指标体系,指标体系考虑了地震强度、防洪、抗滑、抗渗透和安全管理五个方面,能够较为全面的分析和评估尾矿库在抗震方面的基本特性,并通过研究给出了各个指标的分级方法。该体系的建立为尾矿库抗震能力评估、避免特殊工况下尾矿库溃坝事故的发生具有一定应用价值,可为尾矿库运行期的安全管理提供依据。