中纬电离层大尺度扰动的数值模拟

利用计算机模拟研究了不同条件下中纬电离层F区大尺度扰动的时空演变.当存在幅度约为5％的初始扰动时,Perkins不稳定性能发展成为大尺度电离层不均匀体.大气重力波能触发Perkins不稳定性,在更短时间内增长成为大幅度电离层振荡.非均匀局部电场结构也能产生局部电离层的大幅度扰动.本义的模拟表明,中纬电离层大尺度扰动主要表现为磁通管内等离子体沿磁力线的振荡.模拟结果与观测现象符合得很好.     

澳大利亚西部绿岩带的三维构造：对金矿勘探的推断

非洲和加拿大的绿岩带的三维几何形状受到重力、大地电流和地震反射资辩的相当好的约束.对比世界各地的绿岩,显示出它们的总体几何特征处处相似.它们具有典型的厚度约5km,并且有比较平坦的基底.可能由于构造史中的局部差异,使它们与周围花岗岩的接触的倾斜幅度和方向都不相同.绿岩中有时有席状花岗岩体侵入.较厚的花岗岩侵入体形成的岩基已经可以辨认出来.澳大利亚西部绿岩带的少数地球物理研究成果是可以利用的.尽管如此,由于重力数据显示出在某些情况下花岗岩-绿岩的接触带以平缓的角度向远离绿岩带倾斜(逆倾),也有证据表明有些花岗岩是岩席.根据这些观测结果推断,矿化的绿岩可能存在于花岗岩露头区下方.非洲南部的默奇森(Marchison)绿岩和东部金矿区的证据表明,矿化带和隐伏花岗岩岩体之间存在空间相关性.因为最新的花岗岩是由于重力“低”而发现的,所以在绿岩带内区域重力测量可能是一等有用的勘探工具.     

大气重力波产生大尺度赤道扩展F的理论

本文提出了大气重力波触发Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性并导致大尺度赤道扩展Ｆ的理论．重力波作为外部扰动派触发等离子体扰动，这种扰动在Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性的作用下继续增长，经过４００ｓ扰动幅度就能增长到５０％，经过７００ｓ后幅度趋近１００％，即为完全的等离子体泡．由于Ｅ区的影响，赤道扩展Ｆ主要出现于晚上．本文的理论阐明了重力波与Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性相互作用的性质，揭示了大尺度赤道扩展Ｆ的产生机制．     

Economic valuation for the conservation of marine biodiversity

Policy makers are increasingly recognising the role of environmental valuation to guide and support the management and conservation of biodiversity. This paper presents a goods and services approach to determine the economic value of marine biodiversity in the UK, with the aim of clarifying the role of valuation in the management of marine biodiversity. The goods and services resulting from UK marine biodiversity are detailed, and 8 of the 13 services are valued in monetary terms. It is found that a decline in UK marine biodiversity could result in a varying, and at present unpredictable, change in the provision of goods and services, including reduced resilience and resistance to change, declining marine environmental health, reduced fisheries potential, and loss of recreational opportunities. The results suggest that this approach can facilitate biodiversity management by enabling the optimal allocation of limited management resources and through raising awareness of the importance of marine biodiversity.     

First detection of CYP1A1 and CYP2B induction in Mediterranean cetacean skin biopsies and cultured fibroblasts by Western blot analysis

The need to develop powerful tools to detect exposure and effects of POPs and emerging contaminants in Mediterranean cetaceans led us to develop a suite of sensitive non-lethal biomarkers in integument biopsies of free-ranging animals. In order to propose induction of CYP1A1 and CYP2B, detected by Western blot analysis, as biomarkers of exposure to OCs, PAHs and PBDEs, a three-phase experimental protocol (in vitro experiments, calibration experiments and field applications) was followed using fibroblast cell cultures and biopsies of Mediterranean Stenella coeruleoalba and Tursiops truncatus. This methodology was confirmed to be sensitive and stable in comparison to previous methods used to detect CYP1A1 in biopsies, enabling analysis of several inducible proteins in non-lethal samples and analysis of material from stranded animals.     

Effects of chemical dispersants and mineral fines on crude oil dispersion in a wave tank under breaking waves

The interaction of chemical dispersants and suspended sediments with crude oil influences the fate and transport of oil spills in coastal waters. A wave tank study was conducted to investigate the effects of chemical dispersants and mineral fines on the dispersion of oil and the formation of oil-mineral-aggregates (OMAs) in natural seawater. Results of ultraviolet spectrofluorometry and gas chromatography flame ionized detection analysis indicated that dispersants and mineral fines, alone and in combination, enhanced the dispersion of oil into the water column. Measurements taken with a laser in situ scattering and transmissometer (LISST-100X) showed that the presence of mineral fines increased the total concentration of the suspended particles from 4 to 10microl l(-1), whereas the presence of dispersants decreased the particle size (mass mean diameter) of OMAs from 50 to 10microm. Observation with an epifluorescence microscope indicated that the presence of dispersants, mineral fines, or both in combination significantly increased the number of particles dispersed into the water.     

The movement of oil under non-breaking waves

The combined effects of wave kinematics, turbulent diffusion, and buoyancy on the transport of oil droplets at sea were investigated in this work using random walk techniques in a Monte Carlo framework. Six hundred oil particles were placed at the water surface and tracked for 500 wave periods. A dimensionless formulation was presented that allowed reporting distances in terms of the wave length and times in terms of the wave period. Stokes' drift was, expectedly, the major mechanism for horizontal transport. It was also found that plumes that have large terminal rise velocities move faster forward but spread less than those that have small terminal rise velocities. The increase in wave slope (or wave steepness) caused an increase in transport and spreading of the plume. Our results supported treating the oil as completely mixed vertically in a layer near the surface. In the horizontal direction, buoyant plumes had spreading coefficients that are essentially constant after about 200 wave periods. But neutrally buoyant plumes had horizontal spreading coefficients that increased with time (for the simulation time of 500 wave periods). Techniques for generalizing the results for a wide range of wave parameters were presented.     

Investigation of natural and anthropogenic hydrocarbon inputs in sediments using geochemical markers. II. Sao Sebastião, SP--Brazil

The S?o Sebasti?o Channel, NE S?o Paulo State, Brazil, is an area of environmental interest of that state not only because of the tourism, but also because of the presence of the most important oil terminal of Brazil, the PETROBRAS Maritime Terminal (DTCS). Sediment samples were collected at 15 sites in the channel, extracted and analyzed by GC/FID and GC/MS for composition and levels of the following organic geochemical markers: aliphatic hydrocarbons (normal and isoprenoid alkanes), petroleum biomarkers, linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs). The total concentrations varied from 0.04 to 8.53 micorg g(-1) for aliphatics, from 51.1 to 422.0 ng g(-1) for petroleum biomarkers, from 12.6 to 27.7 ng g(-1) for LABs and from 20.4 to 200.3 ng g(-1) for PAHs. The PETROBRAS Maritime Terminal (DTCS), Sao Sebasti?o Harbor and sewage outfalls along the area had clear influences on the geochemical marker concentrations, especially at locales in the central and north parts of the channel.     

Removal of ammonia toxicity in marine sediment TIEs: a comparison of Ulva lactuca,zeolite and aeration methods

Toxicity Identification Evaluations (TIEs) can be used to determine the specific toxicant(s), including ammonia, causing toxicity observed in marine sediments. Two primary TIE manipulations are available for characterizing and identifying ammonia in marine sediments: Ulva lactuca addition and zeolite addition. In this study, we compared the efficacy of these methods to (1) remove NH(x) and NH(3) from overlying and interstitial waters and (2) reduce toxicity to the amphipod Ampelisca abdita and mysid Americamysis bahia using both spiked and environmentally contaminated sediments. The utility of aeration for removing NH(x) and NH(3) during a marine sediment TIE was also evaluated preliminarily. In general, the U. lactuca and zeolite addition methods performed similarly well at removing spiked NH(x) and NH(3) from overlying and interstitial waters compared to an unmanipulated sediment. Toxicity to the amphipod was reduced approximately the same by both methods. However, toxicity to the mysid was most effectively reduced by the U. lactuca addition indicating this method functions best with epibenthic species exposed to ammonia in the water column. Aeration removed NH(x) and NH(3) from seawater when the pH was adjusted to 10; however, very little ammonia was removed at ambient pHs ( approximately 8.0). This comparison demonstrates both U. lactuca and zeolite addition methods are effective TIE tools for reducing the concentrations and toxicity of ammonia in whole sediment toxicity tests.     

Influence of algal farming on fish assemblages

We examined the influence of algal farming on fish assemblages in two shallow coastal lagoons in Zanzibar, Tanzania. Fish assemblages were visually investigated using a belt transect method and the line-intercept technique was used to examine the substrate composition. 101 species of fish belonging to 31 families were recorded. Algal farming affected the associated fish fauna in terms of abundance, species richness, trophic identity and fish community composition. However, the impact differed between the lagoons. Algal farms in one lagoon hosted a more abundant and diversified fish fauna than controls, whereas farms in the other lagoon exhibited lower fish densities and similar species diversity compared to controls. The discrepancies between lagoons may be an effect of differences in farming intensity and character of the substratum.