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1.
The marine–estuarine polychaete Capitella is an indicator of organic pollution and plays important roles in sewage waste cycling. The antidepressant fluoxetine can be accumulated in streams and sewage effluents and it could pose a hazard to infauna. Effects of fluoxetine on feeding and growth of Capitella teleta were investigated through the exposure to 0, 0.001, 0.03, 0.3 and 3.3 μg/g dry weight sediment-spiked fluoxetine during 18 days. No effects of fluoxetine concentrations were observed on egestion rates, body weight and size-specific egestion rates. Fluoxetine favoured the occurrence of males with abnormal genital spines. This suggests that fluoxetine can have important reproductive implications. Further studies are recommended to assess potential detrimental effects on benthic infauna inhabiting close to sewage treatment plants.  相似文献   
2.
李威武  倪光清 《云南地质》2009,28(1):99-101
绳索取心钻探时,斜孔钻进发生的埋钻事故较难处理,在松软易碎地层中埋钻事故又极难预防。经多年实践,提出事故发生后采取优化钻孔井身结构,结合爆破法处理有效省时,节约成本又减少损失。  相似文献   
3.
深水网箱投饵机设计与试验研究   总被引:15,自引:0,他引:15  
根据网箱养殖的特点,结合网箱养殖的经验,设计了1种深水网箱投饵机,并进行了相应的试验,测定了不同情况下产生的真空度以及在冲饵管和吸饵管不同开度时的下料时间。此投饵机使用水力环流供饵、水力抽负吸饵、水动力投饵,充分利用了丰富的海水资源,用汽油机水泵作动力,利用管道将饵料抛向网箱,可向多个、距离不同的网箱供饵。作为1种新的投饵机具,可用于网箱养鱼和池塘养鱼的投饵。  相似文献   
4.
Ophiomorpha irregulaire is a large and extremely rare trace fossil. The type section is in the Book Cliffs, Utah, USA. A second on-shore locality is reported here, in the Nuussuaq Basin of West Greenland. Both occurrences date from the Late Cretaceous. Other reports of O. irregulaire are restricted to two-dimensional sections in well cores and are mostly Jurassic in age. The West Greenland occurrence is in the Atane Formation in shallow marine clean sandstone. The two on-shore localities lie in the same biogeographical region, in connection with the Cretaceous Western Interior Seaway of North America. O. irregulaire is characterized by a sinuous, branched meander maze lying mostly within a single horizontal plane, probably not far beneath the seafloor. The burrow lining has remarkably elongate pellets that probably were emplaced by the burrower. In some cases, diagenetic compression may have deformed the lining pellets to produce their elongated shape. The muddy sediment comprising the lining is almost unrepresented in the clean sands of the substrate, and it was probably trapped from suspension during suspension-feeding activity.  相似文献   
5.
枢纽机场的航班波体系结构及其喂给航线的空间格局研究   总被引:1,自引:0,他引:1  
黄洁  王姣娥 《地理科学》2018,38(11):1750-1758
基于航班波的概念,提出了航班波识别的技术流程和喂给航线的研究方法,并对全国十大枢纽机场的航班波体系进行了研究与甄别。在此基础上,进一步分析了拥有明显航班波体系的枢纽机场的喂给航线空间格局演化。研究发现:① 北京首都、上海浦东、广州白云和昆明长水机场拥有较为明显的航班波体系;成都双流、深圳宝安、西安咸阳机场的航班波体系尚不清晰。②首位航空公司拥有足够的航班数量是机场构建航班波的必要但非充分条件,时刻资源的优化配置更为关键。③北京首都、上海浦东和广州白云三大枢纽机场的国际喂给航线和国内喂给航线在空间上存在显著的差异,且总体上与地理临近性无关,更多地与首位航空公司的航线网络扩张相关。  相似文献   
6.
An extensive suite of igneous sills was intruded into the Tertiary sedimentary section of the Jiaojiang sag,East China Sea.This suite has been well imaged offshore through 2D and 3D seismic surveys,showing a close relationship with CO2 content in nearby gas discoveries.A new observational model,which incorporates simple upward propagation,simple horizontal propagation,and transgressive propagation,was proposed to interpret these sill intrusions.In this model,the source magma of the saucer-shaped sills was injected from their lowest points near the center.The transgressive propagation can be interpreted as a combination of the vertical and horizontal propagation.Most shallow sub-volcanic intrusions in the Jiaojiang sag exhibit fingered characteristics,both vertically and horizontally.The vertical fingered propagation produced saucer-shaped sills arranged in the flower style.Along the brims of lower sills could usually be found the upper sills,which are interpreted to have formed simultaneously with or later than the lower feeder sills.In the second type,the chilled paths of the older sills were reutilized by subsequent intrusions.The horizontal fingered propagation formed sheet intrusions that exhibit groove,lobate,tubular,and crevasse splaylike geometry in plan view.In 3D view,the sheet intrusions have still preserved the lower center and higher rim that similar with the sub-rounded saucer-shaped sills.Although fracture propagation may be important,flow inflation was the key mechanism of magma intrusion.Further consideration of the mechanisms underlying sill formation may help explain the fingered characteristics of sill propagation.  相似文献   
7.
The changing chemical composition of cloud water and precipitation in the Western Sudety Mountains are discussed against the background of air-pollution changes in the Black Triangle since the 1980s until September 2004. A marked reduction of sulphur dioxide emissions between the early 1990's and the present (from almost 2 million tons to around 0.2 million tons) has been observed, with a substantial decline of sulphate and hydrogen concentration in cloud water (SO42− from more than 200 to around 70 μmol l− 1; H+ from 150 to 50 μmol l− 1) and precipitation (SO42− from around 80 to 20–30 μmol l− 1; H+ from around 60 to 10–15 μmol l− 1) samples. At some sites, where fog/cloud becomes the major source of pollutants, deposition hot spots are still observed where, for example, nitrogen deposition can exceed 20 times the relevant critical load. The results show that monitoring of cloud water chemistry can be a sensitive indicator of pollutant emissions.  相似文献   
8.
杨国云 《云南地质》2009,28(2):201-205
绳索取芯钻进技术改变传统的提钻取芯过程,降低劳动强度,大幅度提高时间利用率、钻探效率及取芯质量。目前,绳索取芯钻进方法已经广泛应用于地质勘探、工程勘察和水文工程地质等多种要求采取岩芯的钻进工程中。本文结合云南某矿区勘察工程钻孔实例,通过小口径绳索取芯钻进工艺与普通取芯钻进工艺对比来说明其先进、高效的特点。  相似文献   
9.
This paper describes the development of a computational model to predict the response of synthetic-fiber ropes under both monotonic and cyclic loads. The model addresses the issue of damage to a rope cross-section and its effect on rope response. Isotropic damage is assumed and is therefore characterized by a scalar quantity known as the damage index. The damage index is used to quantify the amount of deterioration that takes place in a damaged rope throughout its loading history. For the current study, data obtained from static tension tests are used to determine the evolution relationship for the damage index. This relationship is based on the stiffness ratio between experimental data and simulation of rope response without any source of damage and is assumed to be described by an exponential equation. Numerical simulations of damaged rope behavior compare well with experimental results.  相似文献   
10.
Nutrient loads from the land to the sea must be reduced to combat coastal eutrophication. It has been suggested that further mitigation efforts are needed in the brackish Baltic Sea to decrease nutrients, especially in eutrophic coastal areas. Mussel farming is a potential measure to remove nutrients directly from the sea. Mussels consume phytoplankton containing nitrogen (N) and phosphorus (P); when the mussels are harvested these nutrients are removed from the aquatic system. However, sedimentation of organic material in faeces and pseudo-faeces below a mussel farm consumes oxygen and can lead to hypoxic or even anoxic sediments causing an increased sediment release of ammonium and phosphate. Moreover, N losses from denitrification can be reduced due to low oxygen and reduced numbers of bioturbating organisms. To reveal if mussel farming is a cost-effective mitigation measure in the Baltic Sea the potential for enhanced sediment nutrient release must be assessed.  相似文献   
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