Spatial Distributions of Legacy Contaminants in Sediments of Lakes Huron and Superior

The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in order to evaluate the extent of surficial sediment contamination of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons (PAHs), and metals. Sediment concentrations of PCBs, OCs, PAHs, and mercury were generally low and up to 2 orders of magnitude less than in Lakes Erie and Ontario. In contrast, concentrations of metals such as arsenic, copper, and nickel were comparable to those in Lakes Erie and Ontario. These elevated Lakes Superior and Huron metal concentrations were attributed to naturally occurring metals within the bedrock, soil, and sediment of the study region. Concentrations of all contaminants were typically below the Canadian Sediment Quality Probable Effect Level (PEL) guidelines. With regard to spatial patterns, most contaminants were focused primarily in the depositional basins and atmospheric deposition was likely the major source of these chemicals to the lakes. The major exception was for metals (not including mercury) whose patterns were also influenced by natural sources as well as extensive mining activity. A comparison between surficial sediment contamination of samples collected as part of this survey and those collected in the late 1960s/early 1970s using similar methods showed that concentrations of DDT, PCB, lead, and mercury were generally similar between these two time periods. These results are not consistent with production and usage patterns that have declined substantially in the past 3 decades. We hypothesize that the lack of temporal trends is an artifact due to slow sediment accumulation rates as well as differences in analytical protocols between the two time periods.     

厚冲积层大采深条件下的地表岩层移动规律探讨

针对某矿厚冲积层大采深条件下的地表和岩层移动规律展开研究,通过建立地表移动变形观测站,获取了现场实测数据,采用理论分析和数值模拟等相结合的方式,求取了该矿厚冲积层大采深条件下的地表和岩层移动变形规律。利用1stOpt数据处理软件分析了地表移动变形特征,得到了实测岩移角量参数,采用1stOpt软件回归分析得到了地质采矿要素与岩移参数间的关系式;并通过数值模拟,分析了厚冲积层大采深条件下采动岩体的应变特征和地表移动变形分布特征。     

浅析煤炭开采对陕西榆林市明长城遗址的影响及保护措施

分析了煤炭的开采对榆林市明长城遗址的影响,并提出了相应的保护措施。     

Revision of the needle-shaped Fragilaria species (Fragilariaceae,Bacillariophyta) in the Laurentian Great Lakes (United States of America,Canada)

We investigated several common, needle-shaped diatoms to better characterize the taxonomy of the genus Fragilaria in the Laurentian Great Lakes. We conducted diatom morphometric analysis facilitated by SEM and LM imaging on samples collected as a part of the USEPA’s long-term biological monitoring program. We resolved several decades-long taxonomic problems in the Great Lakes. The results indicated that previous records of species formerly belonging to the genus Synedra, such as S. (Fragilaria) ostenfeldii, S. (Fragilaria) radians, and S. filiformis, should be corrected as these species likely do not occur in the Great Lakes. Valve morphology confirmed the presence of four previously undescribed species: Fragilaria andreseniana sp. nov., Fragilaria stoermeriana sp. nov., Fragilaria limnetica sp. nov., and Fragilaria michiganensis sp. nov. The morphology of several other Fragilaria taxa in the Great Lakes was examined, including a teratologic taxon (Fragilaria sp. 1), Fragilaria crotonensis, Fragilaria grunowii, and a taxon showing morphological affinity to Fragilaria lemanensis (reported here as Fragilaria cf. lemanensis). The spatial and seasonal distributions of these needle-shaped taxa were also analyzed and discussed.     

Evidence of lake trout (Salvelinus namaycush) natural reproduction in Lake Erie

Native lake trout were extirpated from Lake Erie around 1965 and committed restoration efforts began in 1982. In 2021 and 2022, a total of six lake trout (Salvelinus namaycush) in the free embryo or post-embryo life stage were captured in lake trout embryo traps in Lake Erie offshore of Shorehaven Reef, NY. This represents the first conclusive evidence of successful natural reproduction since extirpation. Trapping locations were identified using the results of a fine-scale positioning acoustic telemetry array, visual observations of adult lake trout exhibiting spawning behavior, and underwater cameras to visually identify possible spawning locations. Lake trout utilized a very specific spawning habitat type—the eastern side of shallow offshore humps in 5–8 m of water. These sites were comprised of habitat typically associated with lake trout spawning with slopes of 5–14° and clean rubble-cobble sized rock with visible interstitial spaces. Genetic barcoding was used to identify the post-embryo stage salmonids to species, and microsatellite genotypes assigned strongly to the Seneca strain which comprises the majority of the adult population. These findings represent a significant milestone for lake trout rehabilitation efforts in Lake Erie, confirming that successful reproduction to the post-embryo stage is possible and supporting continued rehabilitation efforts by Lake Erie management agencies.     

福建省体育馆工程施工技术研究

福建省体育馆工程是建设部重点实施技术示范工程,在施工中结合工程施工特点和创优目标,研究、开发、应用了四大类共10余项重点实施新技术,完成了推新任务和创优的目标。     

Automated Mapping of Surface Water Temperature in the Great Lakes

A procedure for producing daily cloud-free maps of surface water temperature in the Great Lakes has been developed. It is based on satellite-derived AVHRR (Advanced Very High Resolution Radiometer) imagery from NOAA's CoastWatch program. The maps have a nominal resolution of 2.6 km and provide as complete as possible coverage of the Great Lakes on a daily basis by using previous imagery to estimate temperatures in cloud covered areas. Surface water temperature estimates derived from this procedure compare well with water temperatures measured at the eight NOAA weather buoys in the lakes. The mean difference between the buoy temperature and the satellite-derived temperature estimates is less than 0.5°C for all buoys. The root mean square differences range from 1.10 to 1.76°C.As one example of the possible applications of this product, the daily surface water temperature maps for 1992 to 1997 were analyzed to produce daily estimates of average surface water temperature for each lake. Results are compared to the long-term (28 year) mean annual cycle of average surface water temperatures. The average surface water temperatures vary from as much as 4°C below climatology in 1993 to 2 to 3°C above climatology in 1995. The new analysis procedure also provides a more realistic depiction of the spatial distribution of temperature in the springtime than the climatological maps.     

Undergraduate studies in energy education – A comparative study of Greek and British courses

Undergraduate energy education in Greece is compared with relevant accredited courses of the United Kingdom, with the aim to transfer good practices applied in the latter for the development and improvement of the Greek courses. Despite the encouraging prospects for energy engineering courses, the situation in Greece seems declining, with only one course being offered in this period. The (unique) Greek course seems to share the same basis with the majority of the British accredited courses, but also a few peculiarities that could be amended for the improvement of the course.     

高能脉冲电源及其在铸造中的应用研究

介绍自行研制的一款电压在1～3 kV、最大峰值电流可达1.7MA的脉冲发生装置--XJDMC型高能脉冲电源。电源的电压、输出能量可以调节,能够对充电电压、储能电容、充放电时间进行设置。研究了电压在1、2 kV,电流脉冲峰值为1.7MA时对Al-4wt%Cu合金铸造组织的影响。分析了Al-4wt%Cu合金组织的晶粒尺寸和脉冲电流、电压、冲击频率以及电路自振荡频率之间的相关性。结果表明：脉冲电压2kV、电容的冲击频率为0.5 Hz、电路的振荡频率为50 Hz时,脉冲电流对Al-4wt%Cu合金作用后,晶粒尺寸由1.5mm减小到0.2 mm。在合金凝固过程中施加脉冲电流能够有效细化晶粒尺寸,提高合金的力学性能。     

基于地域文脉背景下的公路动态景观的个性营造

公路动态景观的个性是体现城市地域文化的重要标志.本文从地域文脉背景下的公路景观特质分析入手,针对现存的问题,总结公路动态景观的个性设计策略,并结合以景观绿化为个性的320国道富阳段景观设计应用案例,探讨公路动态景观如何有机结合地域文脉,以实现个性营造对公路动态景观设计的有益探索.