国家地震局地震台阵技术考察组赴挪威和联邦德国考察概况(之二) 四、挪威地震台阵和挪威区域地震台阵系统的技术设施

1.野外设施与数据传递挪威地震台阵中心(NORSAR)的子阵呈圆形,有六个短周期垂直向拾震器和一个三分向长周期拾震器,均置于地下室或浅井中(3—15米)。各子阵拾震器的模拟量输出经前置放大后,由地下电缆传到子阵中心的地下室,再经滤波器、模数转换后合成数字信号,并经调     

国家地震局地震台阵技术考察组赴挪威和联邦德国考察概况(之三)

五、联邦德国的台阵设施1.GRF 台阵的野外设施在单分向台站,拾震器输出分成4级,放大器增益依次为1、4、8、8,这样,经过4档放大器的信号较第一级输出放大倍率为256。这4级输出分别由16位的模数转换器数字化,并送入 LSI 2/20计算机。在计算机中选择这4个输入中尾数有效数字最多而又未限幅的一个,取12位(含符号位),与4位阶码组成新的16位数,经过1200波特的数传机经电     

A survey of census bureau population projection methods

Population projections methods of the U.S. Census Bureau draw upon several different traditions of forecasting: demographic accounting, judgmental, time series, deterministic, and explanatory. This paper reviews each of the forecasting traditions in population projections, describes the U.S. Census Bureau's current methods for national and state population projections, and proposes new hybrid approaches such as demographic-time series methods for national fertility projections and economic-demographic methods for state migration projections. Throughout the article, possible parallels with forecasting in other disciplines are noted.     

What can meteorites tell us about nebular conditions and processes during planetesimal accretion?

Analysis of the most primitive meteorites can yield detailed information about environmental conditions and physical/chemical processes in the earliest Solar System, including the nebular stage during which planetesimals were accreted. Such information pertains to time scales, thermal and chemical evolution, inhomogeneity and mixing, magnetic fields, and grain growth in the solar nebula. Nebular processes identified include evaporation, condensation, localized melting, and fractionation both of solids from gas and among different solids. Little direct evidence remains even in primitive meteorites of the actual accretion process. The absence of intrinsic factors capable of enhancing accretion among meteoritic constituents suggests that gravitational instabilities might have been important in promoting planetesimal accretion.     

关于在震源机制解的沙滩球表示中包括滑动矢量的建议

建议在地震震源机制解的沙滩球表示中包括滑动矢量,从而更直观地显示地震断层错动特性。文中还给出了在Matlab环境中实现的两个带有滑动矢量的沙滩球投影图举例,其中一个使用的是真实数据,另一个使用的是合成数据。     

Herbicide contamination and the potential impact to seagrass meadows in Hervey Bay, Queensland, Australia

Low concentrations of herbicides (up to 70 ng l(-1)), chiefly diuron (up to 50 ng l(-1)) were detected in surface waters associated with inter-tidal seagrass meadows of Zostera muelleri in Hervey Bay, south-east Queensland, Australia. Diuron and atrazine (up to 1.1 ng g(-1) dry weight of sediment) were detected in the sediments of these seagrass meadows. Concentration of the herbicides diuron, simazine and atrazine increased in surface waters associated with seagrass meadows during moderate river flow events indicating herbicides were washed from the catchment to the marine environment. Maximum herbicide concentration (sum of eight herbicides) in the Mary River during a moderate river flow event was 4260 ng l(-1). No photosynthetic stress was detected in seagrass in this study during low river flow. However, with moderate river flow events, nearshore seagrasses are at risk of being exposed to concentrations of herbicides that are known to inhibit photosynthesis.     

Biodegradation of petroleum hydrocarbons at low temperature in the presence of the dispersant Corexit 9500

Our study examined the effects of Corexit 9500 and sediment on microbial mineralization of specific aliphatic and aromatic hydrocarbons found in crude oil. We also measured gross mineralization of crude oil, dispersed crude oil and dispersant by a marine microbial consortium in the absence of sediment. When provided as carbon sources, our consortium mineralized Corexit 9500 the most rapidly, followed by fresh oil, and finally weathered oil or dispersed oil. However, mineralization in short term assays favored particular components of crude oil (2-methyl-naphthalene > dodecane > phenanthrene > hexadecane > pyrene) and was not affected by addition of nutrients or sediment (high sand, low organic carbon). Adding dispersant inhibited hexadecane and phenanthrene mineralization but did not affect dodecane and 2-methyl-naphthalene mineralization. Thus, the effect of dispersant on biodegradation of a specific hydrocarbon was not predictable by class. The results were consistent for both high and low oiling experiments and for both fresh and weathered oil. Overall, our results indicate that environmental use of Corexit 9500 could result in either increases or decreases in the toxicity of residual oil through selective microbial mineralization of hydrocarbons.     

Effects of chitin on microbial emulsification, mineralization potential, and toxicity of bunker C fuel oil

Bunker C, one of the most frequently spilled petroleum products in the US, is difficult to remove from oiled surfaces and is relatively recalcitrant to biodegradation; therefore, emulsification and biodegradability must be optimized before bioremediation can be considered a viable treatment option. Sand from a freshly oiled beach near Dutch Harbor, Alaska, was incubated at 10 degrees C with nutrients (Bushnell-Haas (BH)) or nutrients with crab shell chitin (BH-C). BH-C amendment resulted in greater numbers of bunker C emulsifiers and greater mineralization potentials for hexadecane, phenanthrene, and fluorene than with BH only. Compared to BH alone, mineralization potentials for bunker C also were higher in BH-C, with an estimated 8% of fuel oil mineralized after 6 weeks. Microbially emulsified oil was more toxic than in uninoculated controls (p < 0.05) as measured by Microtox assays. However, toxicity was significantly lower in BH-C than BH after 4 and 6 weeks incubation (p < 0.05).     

Large-scale oil-in-ice experiment in the Barents Sea: monitoring of oil in water and MetOcean interactions

A large-scale field experiment took place in the marginal ice zone in the Barents Sea in May 2009. Fresh oil (7000 L) was released uncontained between the ice floes to study oil weathering and spreading in ice and surface water. A detailed monitoring of oil-in-water and ice interactions was performed throughout the six-day experiment. In addition, meteorological and oceanographic data were recorded for monitoring of the wind speed and direction, air temperature, currents and ice floe movements. The monitoring showed low concentrations of dissolved hydrocarbons and the predicted acute toxicity indicated that the acute toxicity was low. The ice field drifted nearly 80 km during the experimental period, and although the oil drifted with the ice, it remained contained between the ice floes.