太平洋板块相对欧亚板块的运动及其与欧亚板块东缘新生代扩张的潜在关系

太平洋板块相对欧亚板块的运动及其与欧亚板块东缘新生代扩张的潜在关系Ｃ．Ｊ．Ｎｏｒｔｈｒｕｐ等Ｍｏｌｎａｒ和Ｔａｐｐｏｎｎｉｅｒ（１９７５，１９７７）首次提出亚洲的许多构造特征与印度一欧亚板块碰撞带中的地壳碎块侧向消亡有关．他们认为欧亚的东缘为一自由边...     

小震的综合识别研究ht

采用现代数字信号处理方法，对中国地震局地球物理研究所研制的数字地震仪在山西省大同地区1999年11月记录的三分向数字地震资料进行分析，研究了数字地震记录信号的自动识别．结果表明，通过采用长短时信号平均值比、谱分析和小波分析法提取特征参量进行综合识别的方法，可对地震信号进行人机交互式自动识别，且对多数ML＞2.0地震识别较好．      

地震观测信息技术创新思考

1 地震学是观测的科学,高新技术推动现代地震学发展 地震学是观测的科学,纵贯现代地震学的发展,地震观测离不开高新技术的发展.高新技术(以信息技术为代表)主要指传感器技术、遥测技术、遥感技术、通信技术、计算机技术、网络技术.地震学近代经历了几个阶段:经典地震学阶段也称模拟地震学,定量地震学阶段也称数字地震学.     

Flame retardants (PBDEs) in marine turtles, dugongs and seafood from Queensland, Australia

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in numerous products. These compounds have been found to enter the marine environment where they have the potential to bioaccumulate in biota. Limited information is currently available concerning the levels of PBDEs in Australian marine wildlife. This study presents baseline information on PBDE levels in a variety of marine species from Queensland, Australia and considers the influence of species-specific factors on contaminant levels and tissue distribution in marine turtles. Overall, the PBDE levels measured in this study are relatively low compared to marine biota from the northern hemisphere, indicating low level input into the marine system of Queensland. This is in general agreement with global estimates which suggest low PBDE usage in Australia. Previous studies, however, have found relatively high PBDE levels in Australian human milk and sera. This discrepancy in contamination trends between terrestrial and marine biota suggests that future transport of PBDEs may occur to the marine system in Australia.     

Geochemical quantification of semiarid mountain recharge

Analysis of a typical semiarid mountain system recharge (MSR) setting demonstrates that geochemical tracers help resolve the location, rate, and seasonality of recharge as well as ground water flowpaths and residence times. MSR is defined as the recharge at the mountain front that dominates many semiarid basins plus the often-overlooked recharge through the mountain block that may be a significant ground water resource; thus, geochemical measurements that integrate signals from all flowpaths are advantageous. Ground water fluxes determined from carbon-14 ((14)C) age gradients imply MSR rates between 2 x 10(6) and 9 x 10(6) m(3)/year in the Upper San Pedro Basin, Arizona, USA. This estimated range is within an order of magnitude of, but lower than, prior independent estimates. Stable isotopic signatures indicate that MSR has a 65% +/- 25% contribution from winter precipitation and a 35% +/- 25% contribution from summer precipitation. Chloride and stable isotope results confirm that transpiration is the dominant component of evapotranspiration (ET) in the basin with typical loss of more than 90% of precipitation-less runoff to ET. Such geochemical constraints can be used to further refine hydrogeologic models in similar high-elevation relief basins and can provide practical first estimates of MSR rates for basins lacking extensive prior hydrogeologic measurements.     

Behavior of gasoline pools following a denatured ethanol spill

In 1999, approximately 72 m3 of denatured fuel-grade ethanol spilled at a bulk fuel terminal that had existing contamination within the subsurface. An unanticipated increase in the measured depth of the light nonaqueous phase liquid (LNAPL) was observed in nearby monitoring wells following the spill. This paper presents results of a laboratory analysis designed to understand the apparent increase in LNAPL mobility at this site. The two-dimensional stainless steel and glass tank allowed visual assessment of the potential effects that the addition of denatured ethanol may have on a site with pre-existing gasoline contamination. Digital images of gasoline and ethanol spill experiments were analyzed for changes in the characteristics of the existing gasoline pool and residual gasoline saturation in the unsaturated zone. Reductions in the surface and interfacial tensions resulted in significant changes in the size, shape, and saturation of the gasoline pool after the addition of ethanol to the system. The final gasoline pool occupied a smaller area and had a higher saturation. In addition, some smearing of the gasoline into the saturated zone occurred as the capillary fringe was depressed.     

A synthesis of dominant ecological processes in intensive shrimp ponds and adjacent coastal environments in NE Australia

One of the key environmental concerns about shrimp farming is the discharge of waters with high levels of nutrients and suspended solids into adjacent waterways. In this paper we synthesize the results of our multidisciplinary research linking ecological processes in intensive shrimp ponds with their downstream impacts in tidal, mangrove-lined creeks. The incorporation of process measurements and bioindicators, in addition to water quality measurements, improved our understanding of the effect of shrimp farm discharges on the ecological health of the receiving water bodies. Changes in water quality parameters were an oversimplification of the ecological effects of water discharges, and use of key measures including primary production rates, phytoplankton responses to nutrients, community shifts in zooplankton and delta15N ratios in marine plants have the potential to provide more integrated and robust measures. Ultimately, reduction in nutrient discharges is most likely to ensure the future sustainability of the industry.