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151.
中温热液脉系中胶态金和二氧化硅的关系 总被引:2,自引:0,他引:2
后来结晶成石英的非晶质的硅胶(胶态)的最初沉淀,呆以很好地解释中温热液含金石英脉的一些结构特征,它可以生发于粘-滑破裂导致流体压力骤然下降的脆-韧性剪切带中,这个过程使热流体迅速过饱和由于有利的运动学条件,使非晶质的二氧化硅沉淀而不形成石英,减压作用一般也导致流体不混合以及可深的金的络合物不稳定,介是,胶态二氧化硅的存在可以稳定流体中的胶态金,并使微粒金呈悬浮状态作进一步的迁移,在中温热液条件下硅 相似文献
152.
PENG Qiming Chinese Geological Survey Funei Street Xisi Beijing China M. R. PALMER Department of Geology University of Bristol Bristol BS RJ United Kingdom 《Continental Dynamics》1999,(1)
1.IntroductionFig.1. RegionalgeologyoftheeasternLiaoningSouthernJilinarea(AfterZhang,1984) ThePaleoproterozoicvolcanicsedimentarysequence,i.e.,theSouthLiaoheGroupandNorthLiaoheGroup,extendsbetweentwoArchaeancratons(Fig.1).Abundantmineralresources… 相似文献
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Transient recharge to the water table is often not well understood or quantified. Two approaches for simulating transient recharge in a ground water flow model were investigated using the Trout Lake watershed in north-central Wisconsin: (1) a traditional approach of adding recharge directly to the water table and (2) routing the same volume of water through an unsaturated zone column to the water table. Areas with thin (less than 1 m) unsaturated zones showed little difference in timing of recharge between the two approaches; when water was routed through the unsaturated zone, however, less recharge was delivered to the water table and more discharge occurred to the surface because recharge direction and magnitude changed when the water table rose to the land surface. Areas with a thick (15 to 26 m) unsaturated zone were characterized by multimonth lags between infiltration and recharge, and, in some cases, wetting fronts from precipitation events during the fall overtook and mixed with infiltration from the previous spring snowmelt. Thus, in thicker unsaturated zones, the volume of water infiltrated was properly simulated using the traditional approach, but the timing was different from simulations that included unsaturated zone flow. Routing of rejected recharge and ground water discharge at land surface to surface water features also provided a better simulation of the observed flow regime in a stream at the basin outlet. These results demonstrate that consideration of flow through the unsaturated zone may be important when simulating transient ground water flow in humid climates with shallow water tables. 相似文献
155.
To determine body and tissue compartment-specific burdens (mg) of total mercury (THg), tissues were weighed and analyzed for THg concentration (microg/g fw) in Pacific harbor seal (Phoca vitulina richardii) pups from central California in 2006. THg concentrations were related as follows: hair > liver = kidney = pelt > muscle > other = heart > brain > blubber > bone. THg burden, however, was related as: pelt = muscle > liver = other > kidney = blubber > brain = heart > bone. THg concentration and burden in muscle were strongly associated with delta(15)N. delta(13)C and delta(15)N values were significantly greater in muscle than liver, and delta(13)C was significantly lesser the longer animals were in rehabilitation. Because THg concentration and burden in muscle correlated most significantly with other tissue compartments, we recommend that muscle from the specific sites we sampled be used instead of liver or hair for biomonitoring THg in harbor seals. Assessment of proportional THg burdens within each tissue compartment for harbor seals pups included use of a conceptual model, allowing for more complete visual characterization of THg body burden. 相似文献
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Kastelein RA van der Heul S Verboom WC Triesscheijn RJ Jennings NV 《Marine environmental research》2006,61(1):19-39
To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network (ACME) using underwater sounds to encode and transmit data is currently under development. Marine mammals might be affected by ACME sounds since they may use sound of a similar frequency (around 12 kHz) for communication, orientation, and prey location. If marine mammals tend to avoid the vicinity of the acoustic transmitters, they may be kept away from ecologically important areas by ACME sounds. One marine mammal species that may be affected in the North Sea is the harbour seal (Phoca vitulina). No information is available on the effects of ACME-like sounds on harbour seals, so this study was carried out as part of an environmental impact assessment program. Nine captive harbour seals were subjected to four sound types, three of which may be used in the underwater acoustic data communication network. The effect of each sound was judged by comparing the animals' location in a pool during test periods to that during baseline periods, during which no sound was produced. Each of the four sounds could be made into a deterrent by increasing its amplitude. The seals reacted by swimming away from the sound source. The sound pressure level (SPL) at the acoustic discomfort threshold was established for each of the four sounds. The acoustic discomfort threshold is defined as the boundary between the areas that the animals generally occupied during the transmission of the sounds and the areas that they generally did not enter during transmission. The SPLs at the acoustic discomfort thresholds were similar for each of the sounds (107 dB re 1 microPa). Based on this discomfort threshold SPL, discomfort zones at sea for several source levels (130-180 dB re 1 microPa) of the sounds were calculated, using a guideline sound propagation model for shallow water. The discomfort zone is defined as the area around a sound source that harbour seals are expected to avoid. The definition of the discomfort zone is based on behavioural discomfort, and does not necessarily coincide with the physical discomfort zone. Based on these results, source levels can be selected that have an acceptable effect on harbour seals in particular areas. The discomfort zone of a communication sound depends on the sound, the source level, and the propagation characteristics of the area in which the sound system is operational. The source level of the communication system should be adapted to each area (taking into account the width of a sea arm, the local sound propagation, and the importance of an area to the affected species). The discomfort zone should not coincide with ecologically important areas (for instance resting, breeding, suckling, and feeding areas), or routes between these areas. 相似文献
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