再论A型花岗岩：对一种残余源模式的评价

0 绪言“A型”花岗岩这一术语是由Loiselle和Wones(1979)引入,用于描述沿大陆裂谷带产生(非造山)而具有弱碱性地球化学特点的花岗岩。一般将它解释为结晶于低水逸度条件下。与其它类型花岗岩相比,A型花岗岩具有高Fe/Mg、(Kq+Na)/Al、K/Na比值和高F、Zr、Nb、Ga及稀土元素(REE)和Y及Zn;具低Mg、Ca、Al、Cr、和Ni值(见Collins等,1982和Whalen等,1987)。因而A型花岗岩富集亲石元素而亏损那些I型、M型和S型花岗岩(解释为源于火成地壳、地幔和沉积源)有亲缘关系的耐熔(refractory)元素。Clemens等(1986)发现A     

岩石图象分析在强胶结储层中流体流动通过特征方面的应用：美国,宾夕法尼亚

凯思油田储层是上泥盆系强胶结砂岩，平均孔隙率为１１５。大多数孔隙空间是自生粘土中的显微孔隙。尽管品质较差，但在注水条件下，该储层每口井日产１７桶原油。本文的目的是根据储层孔隙显微结构特征来解释这一现象，对凯思储层薄片的数字图象资料进行统计分析表明，存在五种孔隙类型，其中两种（孔隙类型４和５）是长石溶解的产物，图像分析结果与岩心压汞资料的对比表明，孔隙类型４具有足够大的喉道控制储层的渗透率。然而，若     

怀俄明州积雪场CO2,CH4和N20的通量及其对全球预算的指示意义

三种主要的温室气体－ＣＯ２、ＣＨＲ和Ｎ２Ｏ－在大气中日益升高的浓度总共占所预期的全球变暖效应的约７０％，但是对于其中的任何一种气体来说，生产－消耗预算都是不平衡的。积雪可覆盖北半球陆地面积的４４％￣５３％，并且在高山及亚高山区，可以有好几米深的积雪厚度持续半年多。大多数微量气体预算假定：当土壤被积雪覆盖或土壤温度降至约０℃时，微量气体交换便会停止。因此，通常认为高山及亚高山区土壤是大气ＣＯ２的总汇     

海水中的热液沉淀物和溶解磷酸盐中的P／Fe和V／Fe之间的关系

溶解磷酸盐是海水中海洋浮游植物生长的重要营养物,某些情况下,它能限制原始生产力（Ｋａｒｌ等,１９９５）。在所有的海洋地区,溶解磷酸盐在表层中与浮游生物混在一起,并且在中层水和深层水中被再矿化了。几位科学家的研究表明,在洋中脊顶部和脊侧翼地区的脊顶扩张...     

The influence of underwater data transmission sounds on the displacement behaviour of captive harbour seals (Phoca vitulina)

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.     

Sabella spallanzanii filter-feeding on bacterial community: ecological implications and applications

The filtration process of Sabella spallanzanii Gmelin on bacterial community was studied in a coastal area of the Northern Ionian Sea (Mediterranean Sea) at three sites, S. Vito, Lido Gandoli and Lido Silvana, where some specimens of S. spallanzanii were transplanted. Analyses were performed both on water and worm samples. A total of six microbial groups were examined: culturable heterotrophic bacteria, total culturable bacteria at 37 degrees C, culturable vibrios, total and fecal coliforms and fecal streptococci. The bacterial densities were usually orders of magnitude higher in the worm homogenates than in the corresponding seawater and the highest values were observed in August. The ability of S. spallanzanii to accumulate the microbial pollution indicators suggests this species can be employed as a bioindicator for monitoring water quality. Moreover, the accumulation capability of S. spallanzanii for specific micro-organisms provides a potential role in sewage bioremediation.     

Evidence for estrogenic endocrine disruption in an offshore flatfish, the dab (Limanda limanda L.)

Dab (Limanda limanda) caught in UK offshore waters show evidence of being exposed to estrogenic endocrine disrupters at a relatively low level. Two of 449 males caught between June and July 2005 had markedly elevated levels of vitellogenin (VTG; 21 and 750 microg/ml) and the remainder ranged from <0.01 to 8.6 microg/ml. Omitting the two outliers, there was a very significant positive relationship with the mass of individual males (a feature noted in previous studies on cod). Mean VTG concentrations in males differed significantly between sites. The site with the highest mean (1.6 microg/ml) was North East of the Dogger Bank and the site with the lowest (0.04 microg/ml) was in Cardigan Bay. Mean VTG concentrations in all North Sea fish were significantly higher than English Channel and Irish Sea fish, but this difference disappeared when fish mass was taken into account. VTG concentrations showed no relationship to water depth, stage of sexual maturity or age of the males. Sixty selected male plasmas were assayed for 17beta-estradiol but only two had measurable amounts (assay limit 0.04 ng/ml). Despite being the start of summer, the gonads of many of the males and females (especially those caught in the North Sea) showed signs of sexual maturity (presence of sperm in males and vitellogenic eggs in females). Many females had high VTG concentrations (up to 14 mg/ml) and 78 out of 80 had measurable concentrations of 17beta-estradiol. The cause of elevated VTG levels in male dab is unknown. As seen in cod, the presence of affected males does not appear to be linked to proximity to land or to known point sources of endocrine disrupters. However, our data, showing that larger fish are more likely to have elevated VTG concentrations, suggests a gradual accumulation by marine fish, probably through feeding, of persistent (probably relatively weak) estrogenic compounds.