Photodegradation and Biodegradation Study of a Starch and Poly(Lactic Acid) Coextruded Material

To simulate the behavior of agricultural mulch coextruded poly(lactic acid)(PLA)/starch films, two stages were carried out. The first was an ultraviolet treatment (UV) at 315 nm, during which glass transition temperature T_g, weight, and molecular weight (MW) decreased and a separation between PLA and starch phase was observed. For the second stage, the mineralization of the carbon of the material was followed using the ASTM (D 5209–92 and 5338–92) and ISO/CEN (14852 and 14855) standard procedures. To measure the biodegradability of polymer material, the assessment of the carbon balance allowed determination of the distribution between the carbon rate used to the biomass synthesis or the respiration process (released CO₂), as well as the dissolved organic carbon into the culture medium and the carbon in the residual insoluble material. The influence of the nature of the medium and the standardized procedures on the final rate of biodegradation was investigated. Whatever the standardized method, the biodegradation percentage was significantly stronger in liquid medium (92.4–93.4) than on inert medium (80–83%). In the case of the compost process, only released CO₂ was measured and corresponded to 79.1–80.3%.     

美国职业卫生法规、监管及统计体系

美国是工业发达国家,是世界上最早建立“职业安全和卫生法”的国家之一。基于该法,美国确立以职业安全卫生监察局(OSHA)为执法机构、职业安全卫生复审委员会(OSHRC)为监督机构的职业卫生监管体系;同时,以劳工统计局(BLS)为统计主管机构,建立以“1904规范”为基础的企业雇主对其作业场所职业卫生记录和报告制度,并辅以两种形式的政府主动调查,形成了自下至上和自上至下相结合的调查统计体系。目前,我国职业卫生的调查统计体系尚未形成。因此,需要从工业发达国家的职业卫生法规、监管入手,以系统的方法和思路,分析其调查统计体系,学习工业发达国家的经验。研究结果认为美国的职业卫生统计体系具有上层法律及相关条例完备、组织体系职责分明、形成了政府主动调查与企业记录报告相结合的调查统计体系等明显的特点。     

铀尾矿库渗漏地下含水层中六价铀的几种吸附反应运移模型对比

在铀尾矿地区,溶解态U(Ⅵ)渗漏到含水层中会对周围环境造成严重的威胁.使用反应运移软件PHT3D对U(Ⅵ)在含水层中的迁移和吸附过程进行模拟.结果表明,相比于不考虑吸附情形,考虑吸附的U(Ⅵ)反应迁移阻滞现象明显.线性和Langmuir吸附等温线模型在水动力条件复杂、地球化学条件多变时的模拟效果与表面络合模型相比较差,甚至有时得到与实际相反的结果,这说明了传统Kd吸附经验模型的局限性.由表面络合模型计算得出的分配系数Kd值是时空变化的,其更能反映实际中多变水化学条件下的吸附过程,适合描述复杂的不同水文地球化学条件.     

论美国能源监管立法与能源管理体制

美国联邦政府从20世纪30年代开始制定能源监管立法。依据集中程度和立法主题,美国能源监管立法可分为电力管控、核能监管、能源安全、放松管制等4个发展时期。根据现行美国能源立法．美国能源管理体制分为联邦和州两个层次。在联邦层次,对能源进行监管的部门有美国能源部、联邦能源监管委员会、核能监管署、环境保护署、国会内政部等。其中,能源部主要负责能源发展和安全的大政方针的制定,联邦能源监管委员会的使命在于通过管制和市场的手段执行能源立法及能源政策。在州层次,一般由州能源委员会、州公用事业委员会以及州环保局负责州的能源监管。     

Variability and predictability of sea-level extremes in the Hawaiian and U.S.-Trust Islands—a knowledge base for coastal hazards management

The objective of this study is to provide an improved climatology of sea level extremes on seasonal and long-term time scales for Hawaii and the U.S-Trust islands. Observations revealed that the Hawaiian and U.S.-Trust islands, by and large, display a strong annual cycle. For estimating the statistics of return period, the three-parameter generalized extreme value (GEV) distribution is fitted using the method of L-moments. In the context of extremes (20- to 100-year return periods), the deviations in most of the Hawaiian Islands (except at Nawiliwili and Hilo) displayed a moderate sea-level rise (i.e., close to 200 mm), but the deviations in the U.S.-Trust islands displayed a considerably higher rise (i.e., more than 300 mm) in some seasons due to typhoon-related storm surges. This rise may cause damage to roads, harbors, and unstable sandy beaches. Correlations between the El Niño-Southern Oscillation (ENSO) climate cycle and the variability of seasonal sea level have been investigated. Results show that correlation for the station located west of the International Date Line (DL) is strong, but it is moderate or even weaker for stations east of the DL. The skill of SST-based Canonical Correlation Analyses (CCA) forecasts was found to be weak to moderate (0.4–0.6 for Honolulu, Kahului, Hilo, and Wake, and 0.3 or below for Kahului, Mokuoloe, and Johnston). Finally, these findings are synthesized for evaluating the potential implications of sea level variability in these islands.     

解悟美国气象经济的发展轨迹和经验

美国政府在引导和规范国内气象经济发展的过程中,始终关注并有效抑制国有气象部门的垄断企图,及时果断地采取措施消除不利于气象事业顺应社会经济和技术发展要求的陈规陋习,适时坚定地扶持充满创造活力的民间资本的竞争努力.可以说,没有这种理智而清醒的管理理念,没有这种不昧于时的前赡眼光和超脱手法,没有这种不拘于内的国际视野和全球战略,是断难有其今天的作为的.我国气象经济的起步较美日等发达国家要晚近40年,更因发展思路不明至今已远远落后于诸多国家.如今面对国内社会经济发展对气象信息日益广泛而精细化的迫切需求,面对全球"气候政治"氛围愈益浓烈的全新形势.特别是"WTO'冲击渡带来的沉重的竞争压力,中国气象经济市场势必将在格局和规则方面进行重大调整.我国在推进气象服务市场化进程中亟需借鉴"美国经验",以确保我国气象事业的健康、协调、可持续发展.     

Characterizing the Relative Contributions of Large Vessels to Total Ocean Noise Fields: A Case Study Using the Gerry E. Studds Stellwagen Bank National Marine Sanctuary

In 2006, we used the U.S. Coast Guard’s Automatic Identification System (AIS) to describe patterns of large commercial ship traffic within a U.S. National Marine Sanctuary located off the coast of Massachusetts. We found that 541 large commercial vessels transited the greater sanctuary 3413 times during the year. Cargo ships, tankers, and tug/tows constituted 78% of the vessels and 82% of the total transits. Cargo ships, tankers, and cruise ships predominantly used the designated Boston Traffic Separation Scheme, while tug/tow traffic was concentrated in the western and northern portions of the sanctuary. We combined AIS data with low-frequency acoustic data from an array of nine autonomous recording units analyzed for 2 months in 2006. Analysis of received sound levels (10–1000 Hz, root-mean-square pressure re 1 μPa ± SE) averaged 119.5 ± 0.3 dB at high-traffic locations. High-traffic locations experienced double the acoustic power of less trafficked locations for the majority of the time period analyzed. Average source level estimates (71–141 Hz, root-mean-square pressure re 1 μPa ± SE) for individual vessels ranged from 158 ± 2 dB (research vessel) to 186 ± 2 dB (oil tanker). Tankers were estimated to contribute 2 times more acoustic power to the region than cargo ships, and more than 100 times more than research vessels. Our results indicate that noise produced by large commercial vessels was at levels and within frequencies that warrant concern among managers regarding the ability of endangered whales to maintain acoustic contact within greater sanctuary waters. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

改性废弃皮革对U(VI)的动态吸附

以改性废弃皮革为吸附剂对U(VI)进行动态吸附实验,采用直径3 cm、高50 cm的玻璃吸附柱,在填料高度为3、4和5 cm,U(VI)溶液进水流速为0.85、1.7和2.55 mL·min-1,初始U(VI)浓度为6、12和18 mg·L-1的条件下,考察了各因素对U(VI)吸附穿透曲线的影响。动态实验表明：柱高的降低、流速的增大和U(VI)浓度的增加均会使穿透时间提前;动态吸附穿透曲线能很好地符合Thomas模型的条件（R2>0.95）,同时吸附量的预测值与实际测试值较为接近。使用穿透时间（ta）与填料高度（h）的关系式ta=220h-433(R2=0.998),在仅改变流速和初始U(VI)浓度时,穿透时间预测值与实际测试值相差较小,表明BDST模型能确定固定床的动态吸附周期。     

美军军事极端环境选择的科学表征

介绍了美国陆军研究办公室资助陆军研究实验室环境科学部和陆军军官学校地理与环境工程部,研发了通过地理环境分析提高利用自然环境进行试验和训练的科学判据,实现了表征任意环境试验站点支持试验任务的能力.在地理环境位置分析中,采用了8步骤环境试验站评价分析模型,并给出了理想热带试验区环境条件分析和理想沙漠环境精确的地理学参数分析...     

高岭土胶体对nZVI修复Pb、U污染硅藻土的影响及机制

纳米零价铁 (nZVI) 大量应用于土壤重金属污染的修复,但由于土壤广泛存在的胶体可协同污染物的迁移与扩散,影响nZVI对土壤的修复效果。针对这一问题,通过硅藻土柱实验和重金属运移速率分析,并采用微观结构表征分析 (SEM) 与物相分析 (XRD) 方法,探究高岭土胶体对nZVI修复铅 (Pb) 、铀 (U) 重金属污染土壤的影响机制。结果表明,nZVI可固化Pb和U,阻滞其运移以修复土壤;高岭土胶体的加入可削弱nZVI对重金属的阻滞效果,增强Pb和U的运移能力;但在高岭土胶体与nZVI同等质量浓度下,高岭土胶体对阻滞效果的影响有限;另外,在Pb、U复合体系中,存在竞争吸附现象,nZVI对Pb的阻滞效果优于U,U的运移更易受到高岭土胶体的影响。本研究结果可为土水重金属污染防治提供参考。