美国机动车污染控制(下)

移动源污染控制政策设计 政策工具的范围由于一定的理由，设计和执行机动车污染控制政策特别困难。首先，从根本上说，控制移动源污染不同于控制固定源污染，因为高度移动的污染源数量奇多，每个体污染排放又相对较少。第二，用于控制移动源污染的各种政策措施还没有得到与固定源替代政策相同的注意力。使人意外的是，大多数国家的法规仍然主要依靠针对生产厂商的新车排放标准。第三，在使用刺激手段以采用环保型交通产品时，人们对针对机动车生产厂商的法规是否比指向使用者的措施是否更有效尚不确定。最后，机动车在现代生活方式中的统治…     

美国机动车污染控制(上)

本文讨论了美国移动污染源控制的政策及其对中国的意义，如机动车排放的政策和趋势，控制机动车污染的各种政策工具，传统的直接立法及新的经济刺激手段等。     

Estimating erosion in a riverine watershed bayou liberty-tchefuncta river in louisiana

GOAL, SCOPE, BACKGROUND: Sheet erosion from agricultural, forest and urban lands may increase stream sediment loads as well as transport other pollutants that adversely affect water quality, reduce agricultural and forest production, and increase infrastructure maintenance costs. This study uses spatial analysis techniques and a numerical modeling approach to predict areas with the greatest sheet erosion potential given different soils disturbance scenarios. METHODS: A Geographic Information System (GIS) and the Universal Soil Loss Equation (USLE) were used to estimate sheet erosion from 0.64 ha parcels of land within the watershed. The Soil Survey of St. Tammany Parish, Louisiana was digitized, required soil attributes entered into the GIS database, and slope factors determined for each 80 x 80 meter parcel in the watershed. The GIS/USLE model used series-specific erosion K factors, a rainfall factor of 89, and a GIS database of scenario-driven cropping and erosion control practice factors to estimate potential soil loss due to sheet erosion. RESULTS AND DISCUSSION: A general trend of increased potential sheet erosion occurred for all land use categories (urban, agriculture/grasslands, forests) as soil disturbance increases from cropping, logging and construction activities. Modeling indicated that rapidly growing urban areas have the greatest potential for sheet erosion. Evergreen and mixed forests (production forest) had lower sheet erosion potentials; with deciduous forests (mostly riparian) having the least sheet erosion potential. Erosion estimates from construction activities may be overestimated because of the value chosen for the erosion control practice factor. CONCLUSIONS: This study illustrates the ease with which GIS can be integrated with the Universal Soil Loss Equation to identify areas with high sheet erosion potential for large scale management and policy decision making. RECOMMENDATIONS: The GIS/USLE modeling approach used in this study offers a quick and inexpensive tool for estimating sheet erosion within watersheds using publicly available information. This method can quickly identify discrete locations with relatively precise spatial boundaries (approximately 80 meter resolution) that have a high sheet erosion potential as well as areas where management interventions might be appropriate to prevent or ameliorate erosion.     

The Nasca and Palpa geoglyphs: geophysical and geochemical data

The Nasca geoglyphs in the stone desert in southern Peru are part of our world cultural heritage. These remarkable drawings have roused the interest of scientists from different disciplines. Here we report the results of integrated geophysical, petrophysical, mineralogical, and geochemical investigations of the geoglyphs at six test sites in the stone desert around Nasca and Palpa. The geomagnetic measurements revealed clear indications of subsurface structures that differ from the visible surface geoglyphs. The high-resolution geoelectrical images show unexpected resistivity anomalies underneath the geoglyphs down to a depth of about 2 m. Remarkable structures were revealed in both vertical and lateral directions. No evidence was found of geochemical or mineralogical alterations of the natural geogenic materials (desert pavement environment versus geoglyphs). Neither salts nor other mineral materials were used by the Nasca people to alter or prepare the surfaces of geoglyphs. This supports the hypothesis that the Nasca people simply removed stone material down to the natural hard pan horizon to create the geoglyphs.     

Toxicity testing with luminescent bacteria – Characterization of an automated method for the combined assessment of acute and chronic effects

The luminescent bacteria test according to EN ISO 11348 is frequently applied in (eco) toxicity testing and is applicable for a huge variety of environmental and industrial samples. A big disadvantage of this method is the very short exposure time, which is expressed in a low sensitivity in regard to substances with a delayed effect. Chronic effects, i.e. interference with cell growth, cannot be assessed with this conventional standard method. The goal of this research was to develop an automated testing system for long term toxicity towards the luminescent bacteria Vibrio fischeri by implementing microtitration-based instrumentation. The optimized method, hereinafter referred to as “kinetic luminescent bacteria test”, can be described as a miniaturized combination of the conventional short-term luminescence inhibition test according to EN ISO 11348 and the Photobacterium phosphoreum growth inhibition test (DIN 38412-37). The validation procedure included the evaluation of six reference compounds (3,4-Dichloroaniline, 3,5-Dichlorophenol, Chloramphenicol, Streptomycin sulfate, Potassium dichromate, Zinc sulfate heptahydrate) and three different endpoints that are acute luminescence inhibition (acute LI) after 30 min, chronic luminescence inhibition (chronic LI) after 24 h and growth inhibition (GI) after 14 h. The optimized method allows the assessment of acute and chronic effects within one test, by what a misinterpretation of the toxicity of substances with delayed bacterial toxicity can be prevented, without abandoning most of the advantages of the conventional short-term test. Therefore, the kinetic luminescent bacteria test is exceptional as an initial screening test for environmental samples or substances with unknown (eco) toxicological characteristics.     

Television viewing and public perceptions of hazards to life

Previous research on public perceptions of lethal or hazardous events have often cited the media as possible causes of inaccurate judgments of the frequencies with which such events are assumed to occur. No attempts have been made empirically to assess relationships between media usage and these perceptions however. A study is reported in which a representative sample from one region of Britain was asked to estimate the likelihood of personal risk from a number of hazards which were then related to how much television, and in particular, television news and documentaries they watched. Results showed that in the presence of controls for sex, age and socio-economic class, the overall amount of viewing, but not of news or documentary viewing in particular, was related to perceptions of personal risk on just four hazards to life out of a list of twelve. Heavy television viewers more often perceived higher risk from lightning, flooding and terrorist bomb attacks than did light television viewers, and medium viewers most often perceived higher risk from cancer. On this evidence it appears that aspects of television viewing are only sporadically related to public perceptions of hazards to life, and that viewing of news and documentary is unrelated to such perceptions.