丽江高美古的天文观测条件

综述对丽江高美古的视宁度、天光亮度、消光系数进行观测的原理、仪器、观测方法和结果．结果表明,高美古是我国南方的优良光学天文台址,视宁度达到世界优良台址的水平     

Terpenoid marker compounds derived from biogenic precursors in volcanic ash from Mount St. Helens,Washington

A volcanic-ash sample obtained after the 1980 eruption of Mount St. Helens, Washington, was analyzed for cyclic terpenoid organic compounds and polycyclic aromatic hydrocarbons using capillary gas chromatography-mass spectrometry-computer techniques. Various tricyclic diterpenoid acids and hydrocarbons were identified including dehydroabietic acid, dehydroabietin, dehydroabietane, simonellite, and retene. Preliminary evidence indicates that these compounds were derived from forest soils or atmospheric aerosols or both in the vicinity of coniferous forests. A diagenetic scheme involving three possible pathways for the conversion of abietic acid to retene is presented.     

用相对灰色关联分析法综合评价金刚石钻头

根据ＴＯＰＳＩＳ法原理，提出一种同时考虑“理想方案”和“负理想方案”的金刚石钻头综合评价灰色关联分析法，结合φ６０ｍｍ绳索取心金刚石钻头评价，说明了该方法的具体应用，并与用其它方法评价的结果进行了对比。     

Pollution studies on Tolo Harbour,Hong Kong

Eight stations were chosen for this 14 month survey of Tolo Harbour in Hong Kong, four of them in the harbour proper and four in the estuaries of the major streams entering the harbour. Various chemical and physical factors were measured twice each month. Water samples were collected for nutrient, phytoplankton, chlorophyll and bacteriological analysis.The annual discharge of nutrients from the four streams into Tolo Harbour has been estimated, based on the nutrient analyses and computation of annual discharge (QA) values for these streams. The seasonal and spatial variations in nutrient content are discussed in relation to the increasing organic pollution of Tolo Harbour. Calculations of various ratios between SiO₃, PO₄, NO₃ and total inorganic N reveal that excessive amounts of phosphate are entering the harbour and subsequently accumulating in the bottom waters and sediments, leading to changes in the trophic condition of this water body and the development of anoxic conditions in the bottom layer.Significant correlation has been demonstrated between standing crop and various environmental parameters in both estuarine and marine waters and similarly between chlorophyll a concentration and various environmental parameters. However, no significant correlation values were obtained between either standing crop or chlorophyll a concentrations, SiO₃Si (the latter presumably due to the predominance of diatoms in the phytoplankton). Neither standing crop nor chlorophyll determinations reveal any evidence of alternating periods of high productivity and decomposition which could explain the deteriorating bottom water conditions. This again is taken as evidence that the high organic inputs are responsible for such deterioration.Increasing TC, FC and FS densities have been noted in Tolo Harbour as a direct result of the increasing organic pollution and ratios between FC and FS densities indicate that in 55% of the samples pollution was derived from human sewage. The bacterial levels well exceeded various international standards for bathing waters and shellfish collection for at least a part of the survey period and at a number of stations for the entire survey period. Pathogenic organisms were also present. This underlines the potential health risks in these waters.Finally, the future prospects for this harbour are discussed in relation to activities such as reclamation and the development of new towns and their impact on water quality.     

The fate of polyaromatic hydrocarbons in an intertidal sediment exposure system: Bioavailability to macoma inquinata (mollusca: Pelecypoda) and abarenicola pacifica (annelida: Polychaeta)

Macoma inquinata, a detritus feeding clam, was exposed for 60 days to coarse-grained, and Abarenicola pacifica, a burrowing polychaete, to fine-grained, sediment. Each sediment contained ¹⁴-C-labelled phenanthrene, chrysene or benzo(a)pyrene. Over 70% of the chrysene and benzo(a)pyrene, but only 8% of the phenanthrene, remained in the coarse sediment during the exposure. Essentially all of the chrysene and benzo(a)pyrene and 70% of the phenanthrene remained in the fine sediment. The concentrations of chrysene and benzo(a)pyrene in the clams rose steadily, reaching levels 11·6 and 5·2 times as high as those in the sediment. The tissue phenanthrene concentration rose for 3 days, then fell to one-eighth of the initial concentration. The concentrations of each of the aromatic hydrocarbons in Abarenicola tissue increased for 2 weeks to four to six times the sediment levels. The tissue concentration of chrysene remained constant thereafter, but the levels of phenanthrene and benzo(a)pyrene fell to three-quarters of their peak values. No intermediate degradation products of any of the hydrocarbons were identified in extracts of sediment from either exposure system, or in solvent extracts of tissue or of tissue digestates.Significant ¹⁴C-activity, associated with non-solvent extractable compounds, remained in tissue digestates of individuals of both species exposed to phenanthrene.     

长偏移距瞬变电磁测深甚晚期响应及视电阻率的数值计算

文中讨论了提高长偏移距瞬变电磁测深甚晚期响应计算精度及相应的全区视电阻率的计算方法。在频率域 ,利用直接数值积分结合连分式展开提高低频段响应的计算精度 ,从而提高时间域甚晚期响应的计算精度。同时 ,利用连分式渐进展开 ,将均匀半空间电阻率表示为该模型长偏移距瞬变电磁测深响应的反函数 ,利用迭代方法求出适合全时间段的全区视电阻率。数值结果表明 ,文中的方法可有效地提高长偏移距瞬变电磁测深 (甚 )晚期数据的模拟与解释精度     

青藏高原清洁地区近地面层臭氧的特征分析

利用瓦里关1994年8月～2001年12月地面臭氧资料，分析了地面O3年季变化，以及不同天气条件下的日变化特征。结果表明，青藏高原洁净地区地面O3具有明显的季节变化且呈缓慢的上升趋势，春季浓度明显高于冬季，最高值出现在每年夏初，而最低值在12月左右。与低纬的Lzana站相比，瓦里关地区地面O3浓度变化趋势与之比较相近，而且，亦呈逐年上升趋势。不同天气条件下，春、夏、秋、冬四个季节地面O3浓度变化不尽相同，晴天和多云天，春、夏、秋季的地面O3变化趋势基本一致，其中，春秋季，晴天O3值高于多云天和降雨天，而冬季和夏季则不明显，说明晴空天气虽然有利于O3浓度的增加，但并不是重要因子之一。各季节降雨、雪天O3浓度的变化情况来看，地面O3在春、秋、冬三个季节变化不大。而夏季与其它季节明显不同，变化幅度很大，日较差在四个季节中为最大，这与雨、雪的冲刷关系很大，并且可能存在雨、雪以及降雨强度的差异。     

DDT,DDE, and PCB residues in fish,crustaceans and sediments from the eastern Mediterranean coast of Turkey

Residues of DDE, DDT and PCBs were determined in four different commercial bony fishes: grey mullet, red mullet, striped mullet and gold bandgoat fish, as well as in shrimps, limpets and sediments obtained from the eastern Mediterranean coast of Turkey. The PCB levels in living organisms and sediments were found to be very low, and in most cases below the detection limits. The DDE and DDT values were relatively high compared to PCBs and there was a linear correlation between the organochlorine residue concentrations and the extractable organic material of the analysed samples.     

一种边坡多滑动面搜索的新方法

近年来关于边坡最危险滑动面的搜索的研究方法主要集中在算法的优化方面,事实上对边坡内次级潜在滑动面的搜索也有必要,而目前相关研究并不多。本文提出一种在FLAC-3D中通过控制强度折减法中的折减系数来实现多条滑动面搜索的新方法,并通过算例来说明。同时采用Bishop法与该方法作对比分析,结果表明两者的计算结果十分接近,局部边坡安全系数误差不到1%,整体边坡安全系数误差不到4%,由此论证了该方法的合理性和可行性。     

利用静止卫星窗区红外亮温反演晴空区风场的初步研究

云导风反演明显的局限是在晴空区无法获取风场。为克服这种局限,提出利用静止卫星红外图像资料反演晴空区风场的方法—时间序列差值法,利用LOWTRAN7对其进行可行性分析,并应用云导风实验系统CWIS进行晴空区导风实验。结果表明：实验结果与NCEP资料低空风场有很好的一致性。因此,在传统的“云导风”基础上,增加晴空区卫星导风,可为卫星遥感资料在台风、梅雨和强对流等天气系统分析预报中的定量应用提供更多的卫星风矢。