地铁运行引起的地面振动实测及传播规律分析

对地铁线路某区间段的地面振动进行实测,采集不同测线和不同测点处的水平方向、竖直方向加速度,并转化为傅里叶幅值谱对其进行衰减规律分析。利用公式将加速度记录换算为振级和分频振级,参照相关的国家标准分析不同距离处的振级和频率成分。对比同一加速度记录中的两对开方向列车引起的地面振动,进一步分析振动衰减的规律。所得到的结果可供地面建筑的隔振减振及城市轨道的规划和设计参考。     

Pharmaceuticals,endocrine disruptors,personal care products,nanomaterials and perfluorinated pollutants: a review

The presence of emerging micropollutants such as pharmaceuticals, endocrine disruptors, personal care products, nanomaterials and perfluorinated substances in the environment remains a great threat to the health and safety of humans and aquatic species. These micropollutants enter the environment via anthropogenic activities and have been detected in surface water, groundwater and even drinking water at nanogram per litre to microgram per litre concentration. To date, limited information exists on the fate, behaviours, and pathways of these micropollutants in the environment. The potential ecotoxicological effects on the receptors due to exposure to individual or mixture of these chemicals still remain unknown. This review provides an overview on pharmaceuticals, endocrine disrupting compounds, personal care products, nanomaterials and perfluorinated pollutants, with emphasis on their occurrences, effects, environmental fates, and potential risk of exposure in water, soil or sediment. Based on the literature survey, it was found that in spite of an extensive research and different developmental efforts on the challenges of emerging micropollutants, the solution to the problem of emerging micropollutants in the environment is far from being solved. The needs for behavioural change among citizens, strong political will and policy formulation on the part of government are identified as possible panacea for combating the growing influence of these potential damaging substances. Suggestions on proactive and precautionary measures that must be taken to protect the environment as well as guarantee the health and safety of humans and aquatic species are provided. Future research should concentrate on the development of a risk based screening models and framework that can predict the sources, fate and behaviours of emerging contaminants in the environment is recommended.     

Influence of nutritional status on some toxic and essential elements in the blood of women exposed to vehicular pollution in Ile-Ife, Nigeria

Blood levels of the elements Cu, Zn, Se, As, Cd, Hg, and Pb have been determined in 62 Nigerian women who were occupationally exposed to vehicular pollution. Mercury was determined using a direct mercury analyzer, while all the other elements were determined by an inductively coupled plasma mass spectrometer system. The mean values for all the toxic elements were all within the recommended desirable/tolerable limits, except for Se (0.44 μg/mL, compared with <0.2 μg/mL recommended by the WHO). More than 98 % of the subjects had blood selenium levels higher than this recommended limit. For As, Hg, and Pb, the corresponding figures of subjects with blood levels above the recommended limits were 4, 8, and 19.3 %, respectively. When the subjects were grouped according to their body mass indexes as normal, underweight, overweight, and obese, analysis of variance shows that mean blood levels of Cu, As, and, to some extent Hg were significantly different in the four nutritional status groups. Blood Hg level correlates significantly with blood As in all the groups, except in obese subjects. Also, a significant correlation between age and blood Hg was observed only in normal subjects and between age and blood Pb only in obese subjects. These results suggest that nutritional status could influence both elemental levels and the interactions between trace elements in the blood of female subjects. Nutrition is therefore a factor to consider in efforts to modify human susceptibility to toxic elements.     

The Spread of Pesticide Practices Among Cost-Efficient Farmers

The purpose of this paper is to analyse the spread of pesticide practices with respect to crop production (wheat, barley, and rapeseed) in French agriculture and to evaluate the potential pesticide reductions for cost-efficient farmers. This is made possible by conducting a double-step analysis based on non-parametric robust technology. First, from a panel data of 650 farms over a 12-year period located in the French department of Meuse, we selected the cost-efficient farms thanks to a robust free disposal hull (RFDH) technology. A second RFDH frontier analysis was run only on the selected cost-efficient farms thus enabling us to reveal the units which minimize the pesticide use per hectare while maintaining constant yields. Therefore, all the different total cost-efficient practices among farmers were evaluated in terms of pesticide per hectare and the minimum uses were selected. Our main conclusion is that the pesticide reductions per hectare for the cost-efficient farms could reach 24 %.     

The fetal intrahepatic umbilical vein as an alternative to cord needling for prenatal diagnosis and therapy

Seventy-one fetal blood samplings (FBS) were attempted from the intrahepatic portion of the umbilical vein (IHV) at 18–34 weeks; 54 were attempted primarily and 17 secondarily after a failed attempt at the placental cord insertion. Fetal blood was obtained in 89 per cent of the cases. Intravascular transfusion (IVT) was attempted on 31 occasions and successful in 24 (77 per cent). In all cases of failed sampling or transfusion via the IHV, prenatal diagnosis and/or therapy was accomplished using alternative procedures. On only one occasion was the procedure postponed. There were no losses or neonatal morbidity attributable to the procedure. FBS from the IHV may be considered as an alternative approach to sampling the placental cord insertion. It is recommended in cases where the approach to the placental cord insertion is difficult or hazardous.     

微波法复合絮凝剂PAFC-PAM的制备及脱色性能

研究了以三氯化铝,三氯化铁和阳离子聚丙烯酰胺为原料,在微波辐照下制备PAFC-PAM复合絮凝剂的工艺条件,探讨了pH值、复合絮凝剂投加量对活性染料模拟废水脱色率的影响,并考察了其对实际印染废水的处理效果。结果表明:在PAM/PAFC质量比为0.25、微波合成功率150W、微波时间3min制得的复合絮凝剂,浊度去除率为98.8%。在pH=8,投加量为42mg/L的最佳絮凝条件下,复合絮凝剂对模拟染料废水脱色率高达97%。与PAFC和PAM相比,PAFC-PAM具有较宽的pH适宜范围和较低的投加量且对实际印染废水的处理效果优于PAFC和PAM。     

Integrated real-time monitoring system to investigate the hypoxia in a shallow wind-driven bay

Corpus Christi Bay (Texas, USA) is a shallow wind-driven bay which experiences hypoxia (dissolved oxygen < 2 mg/L) during the summer. Since this bay is a very dynamic system, the processes that control the hypoxia can last on the order of hours to days. Monitoring systems installed on a single type of platform cannot fully capture these processes at the spatial and temporal scales of interest. Therefore, we have integrated monitoring systems installed on three different platform types: (1) fixed robotic, (2) mobile, and (3) remote. On the fixed robotic platform, an automated profiler system vertically moves a suite of water quality measuring sensors within the water column for continuous measurements. An integrated data acquisition, communication and control system has been configured on our mobile platform (research vessel) for synchronized measurements of hydrodynamic and water quality parameters at greater spatial resolution. In addition, a high-frequency radar system has been installed on remote platforms to generate surface current maps for the bay. With our integrated system, we were able to capture evidence of a hypoxic event in summer 2007; moreover, we detected low dissolved oxygen conditions in a part of the bay with no previously reported history of hypoxia.     

Towards global climate change mitigation: assessment of an afforestation option for Nigeria

This paper assesses the potential of an intensive afforestation program as a measure of reducing the atmospheric concentration of carbon in Nigeria. The results presented are based on the recently completed Nigerian Country Studies Program on Climate Change Mitigation. A comprehensive mitigation analysis process (COMAP) model was employed to carry out detailed cost/benefit evaluation of the mitigation option. The end-use based scenario adopted was considered the most appropriate strategy to sustainably implement the mitigation option in Nigeria.The analyses showed that the country could significantly reduce net carbon emission while at the same time meet all her essential domestic wood needs, if approximately 7.5×10⁶ ha of wasteland could be committed to an afforestation program over the 40 year period of projection. The initial cost of establishing such forest plantations, taking cognisance of the opportunity cost of land averaged at about US$500/ha, or in carbon terms, a unit cost of about $13 per tonne of carbon. In terms of carbon flow, if all the end-product based plantations considered (i.e. fuelwood, poles, pulpwood, sawlogs and veneer) were fully established and maintained, it was estimated that by the year 2030, the total carbon stored in the afforested land would be about 638.0×10⁶ t of carbon with an annual incremental rate of 16.0×10⁶ t of carbon. Other economic indicators (i.e. net present value of benefits, present value of costs and benefit for reduced atmospheric carbon) when evaluated showed that the afforestation option could be economically viable even when the investment capital was discounted at rates ranging from 9 to 33 percent for different wood products. It should be noted, however that implementation of such a program would require huge sums of money and a high degree of commitment on the part of Federal, State and Local governments if the associated financial, social and environmental benefits were to be derived.