Mussels document loss of bioavailable polycyclic aromatic hydrocarbons and the return to baseline conditions for oiled shorelines in Prince William Sound, Alaska

Polycyclic aromatic hydrocarbons (PAH) were measured in mussels (Mytilus trossulus) collected between 1990 and 2002 from 11 sites on the shores of Prince William Sound (PWS), Alaska, that were heavily oiled by the 1989 Exxon Valdez oil spill (EVOS). This study, utilizing the methods of the NOAA Status and Trends Mussel Watch Program, found that concentrations of PAH released from spill remnants have decreased dramatically with time and by 2002 were at or near the range of total PAH (TPAH) of 3-355 ng/g dry weight obtained for mussels from unoiled reference sites in PWS. Time-series TPAH data indicate a mean TPAH half-life in mussel tissues of 2.4 years with a range from 1.4 to 5.3, yielding an annual mean loss of bioaccumulated TPAH of 25%. The petroleum-derived TPAH fraction in mussel tissues has decreased with time, reflecting the decreasing release of EVOS residues in shoreline sediments. These results show that PAH from EVOS residues that remain buried in shoreline sediments after the early 1990s are in a form and at locations that have a low accessibility to mussels living in the intertidal zone.     

Estrogenic responses of larval sunshine bass (Morone saxatilis x M. Chrysops) exposed to New York City sewage effluent

To determine the estrogenicity of effluents from sewage treatment plants (STPs) to larval fish, 2-day-old sunshine bass were exposed to effluents from three STPs serving New York City (NYC), varying in size and treatment level. Estrogenic response was evaluated by measuring vitellogenin (VTG) and estrogen receptor (ER) expression in cytosolic fractions of whole body homogenates. Concentrations of the presumptive endocrine disruptors in the effluents were also measured. VTG and ER levels in sewage-exposed fish were 3-5 times that observed in controls. Combined concentrations of estradiol and estrone ranged from 5 to 13 ng/l and nonylphenol-ethoxylate metabolites (NPEOs: 4-nonylphenol, and 1-, 2-, and 3-nonylphenol-ethoxylates) ranged from 180 to 470 microg/l in chlorinated effluent. Results indicate that both ER and VTG can be used as biomarkers for endocrine disruption in larval fish, and that 4-day exposure to sewage effluent is sufficient to elicit significant expression of these markers in sunshine bass larvae. The extremely higher concentrations of NPEOs found in effluent relative to hormones (approximately 40,000-fold) indicates that surfactant metabolites may be contributing significantly to the estrogenic effects observed.     

The geography of dual career households: a research agenda and selected evidence from secondary data sources for Britain

"Amongst the key dimensions of population and labour market change in most parts of western Europe and other similar economies in the 1990s are low fertility rates, rising numbers of smaller households, increasing female participation rates, growth in higher level non-manual occupations and the spread of flexible employment patterns. This paper explores how these trends have led to an increase in the number and significance of one particular subgroup: dual career households. An overview from available secondary sources of the geography and socio-economic characteristics of such households in Britain is presented, and directions for possible future research on dual career households are outlined."     

A Measurement of Omega from the North American Test Flight of Boomerang

We use the angular power spectrum of the cosmic microwave background, measured during the North American test flight of the Boomerang experiment, to constrain the geometry of the universe. Within the class of cold dark matter models, we find that the overall fractional energy density of the universe Omega is constrained to be 0.85相似文献   

环境卫星在气象业务与研究中的应用——美国气象学会声明（2006年1月25日）

环境卫星已经成为以气候监测和天气预报为目的全球观测系统中日益关键的一部分。但是，正如美国国家科学研究院全国科学研究委员会（NRC）的一份报告（（Earth Science and Application from Space--Urgent Needs and Opportunities to Serve the Nation：地球科学与空间应用技术——紧急需求与服务国家的机会，2005）中所指出的一样：“目前环境卫星系统正面临着崩溃的危险。”（译者注：由于经费预算紧缩以及支持重点向太空探索倾斜，一些已经批准的极具科学与社会价值的计划与项目不再得到支持，被迫取消、缩减规模或延迟。目前，NASA没有计划在“地球观测系统”（EOS：Earth Observing System）平台的6年服役期结束之后替换该系统）。除非立即采取行动，重振美国的地球观测研究计划，并制定一个长期的业务环境卫星发展规划。必须采取措施保障这些计划的不断实施，而且能够得到完善，建造一个低成本、具有灵活性的卫星系统，该系统应是先进的综合地球观测系统的核心部分。在过去的25年中，与天气和气候相关的行业已经引进和采用了许多卫星技术与设备方面的重要进展。尤其是全球各国的气象环境部门和研究机构，他们对卫星遥感资料的依赖性正变得越来越大。