雅西高速冕宁段主要地质灾害类型及发育规律

在资料搜集、野外地质调查的基础上,对雅西高速冕宁段主要地质灾害类型及发育规律进行了分析总结,以期减少和预防高速公路遭受崩塌、滑坡和泥石流等的危害.研究表明,该区地质灾害类型主要为滑坡和泥石流,且以泥石流为主,具有分布广、密度大、危害性大等特点,在空间和时间上具有群发性和集中诱发的特征;地质构造、地形地貌、新构造运动、地层岩性是导致雅西高速冕宁段崩塌、滑坡和泥石流灾害频繁发生的内在影响因素,降雨、地震及人类工程活动是最为重要的诱发因素.     

云凝结核浓度对不同弗罗德数下形成的地形云和降水的影响

云凝结核(CCN)对云和降水的影响除与其物理化学性质密切相关外,还受到气象条件的影响,但此类研究较少。文中基于WRF中尺度数值模式,引入了表征大气层流速、层结稳定度和地形关系的湿弗罗德(Fw)数,研究揭示了CCN浓度的变化对不同Fw下形成的地形云和降水的影响。研究表明,当Fw≤1,接近临界流时,地形阻挡起主要作用,地形抬升和重力波作用主要发生在迎风坡一侧,主要形成层状云和向上游传播的浅对流波状云,降水主要发生在靠近山顶的迎风坡一侧。在此种情况下,CCN浓度升高对地形云和降水影响较小,当CCN浓度由100 cm~(-3)增至1000 cm~(-3)时,云滴含水量增大,但雨水含量减小,说明云粒子向降水粒子的转化效率降低,CCN浓度升高抑制了暖雨过程。但在云发展后期,云滴被上升气流带至高层形成过冷云滴,与雪粒子发生碰并形成霰粒子,使冰相物理过程有所增强。CCN浓度升高可导致20 h累积降水量减少10—15 mm,约减小7%—8%;当Fw1时,CCN浓度升高会导致20 h地形云累积降水量减小超过50%,最大达到96%,导致地形云几乎不产生降水,而且降水量峰值位置向山顶后移动5—10 km。研究表明,降水显著减小的原因不仅与CCN浓度升高有关,过山气流产生的背风坡焚风效应也起了非常重要的作用。由于CCN浓度升高形成了大量云滴粒子,使雨滴形成效率显著降低,不能形成降雨的大量云滴被强过山气流快速带至下游背风坡区,由于背风坡下坡气流的绝热加热形成的焚风效应很显著,导致云滴和雨滴快速蒸发,使降水显著减小。这一结果可以解释在落基山脉、以色列及中国华山发现的地形降水减小30%—50%的现象,说明气象环境条件在气溶胶影响降水中起重要作用,污染气溶胶与背风坡焚风效应产生的叠加效应可造成地形云降水显著减小。     

Seasonal changes in zooplanktonic alkaline phosphatase activity in Toulon Bay (France): the role of Cypris larvae

We studied zooplankton contribution to the total particulate phosphatase activity, the kinetics of this activity, the relation to the different taxonomic groups and the role of particle-bound bacteria. The activity of total particulate material collected from a liter of seawater was more elevated in May, June and August than during the rest of the year. These high activities resulted from a high contribution of the >90 microm fraction which account then for more than 60% of the total particulate activity. Two Michaelian processes with high and low V(max) were disclosed on this fraction. The high V(max) component was responsible for the high summer activities. During these periods, high densities of cirriped Cypris were found which were statistically correlated with this high V(max) component as with its specific activity. Moreover, the contribution of attached bacteria to these high activities was low. In return, this contribution was predominant during the periods of low activity. A simple method was developed to characterise this bacterial activity.     

Effects of the 'Prestige' oil spill on macroalgal assemblages: large-scale comparison

An assessment of the effects of the 'Prestige' oil spill on intertidal, macroalgal assemblages was carried out comparing abundance data obtained before and after the spill. Four zones in the North and Northwest coast of Spain were sampled, one of them located at the immediate vicinity of the spill, the zone most heavily oiled. Macroalgal assemblages had similar structure between years. Neither critical decrease in abundance of the dominant macroalgae, nor increase in opportunistic species were found. Some differences in abundance were observed, but they did not show any pattern, being more likely the result of the natural variability of the assemblage. Extensive, but not intense fuel deposition on the shores and a limited use of aggressive cleanup methods are suggested as possible causes for the lack of the effects in these assemblages after the 'Prestige' oil spill.     

Multivariate discriminant analysis distinguishes metal- from non metal-related biomarker responses in the clam Chamaelea gallina

Molecular biomarkers are among the most sensitive and earliest responses to pollutants. However, lack of detailed knowledge on variability of responses and their possible seasonal variation limit their use. In addition, the seasonality of biological processes modulates the response of organisms to pollutant stressors. Using multivariate statistics, we have studied the influence of environmental and biological factors on the response of a battery of molecular biomarkers in the clam Chamaelea gallina collected along the South-Spanish littoral. Multivariate discriminant analysis clearly distinguished biomarker response between clean and polluted areas, using heavy metals as indicator of pollution. Such differences disappeared when the dataset was normalised for metal content, thus indicating that pollution was the main significant cause of the changes observed between clean and polluted sites. In conclusion, this work shows that, when applying a complete biomarker panel, multivariate statistical tools can be used to discern pollutant- from non pollutant-related responses.     

In situ heavy metals (copper, lead and cadmium) in different plankton compartments and suspended particulate matter in two coupled Mediterranean coastal ecosystems (Toulon Bay, France)

We monitored the concentrations of copper, lead and cadmium in seawater, in suspended particulate matter (SPM) and in bacteria, phyto- and zooplankton communities separated from abiogenic particles, over a one year cycle in two coupled Mediterranean coastal ecosystems (Little Bay (LiB) and Large Bay (LaB)). Metals were present in seawater in the order Cu > Pb > Cd in both bays and showed important variations within the same month than among months. In LiB, their concentrations were between 0.62 and 2.82 μg Cu l⁻¹, 0.16 and 19 μg Pb l⁻¹ and 0.007 and 0.14 μg Cd l⁻¹, respectively, whereas in LaB, they were between 0.23 and 2.11 μg Cu l⁻¹, 0.09 and 0.76 μg Pb l⁻¹ and not detected and 0.65 μg Cd l⁻¹. SPM play an important role on metal adsorption, especially for copper. Bioaccumulation factors showed that bacteria and phytoplankton accumulate metals whereas zooplankton tends to biodiminish them in the plankton food web.     

康定北部高原构造岩溶发育特征与地下水径流带识别

受自然环境和技术方法制约,青藏高原岩溶发育演化和岩溶地下水循环特征研究相对薄弱,制约了青藏高原碳酸盐岩区的经济发展、民生设施建设和地质灾害防治.通过野外地质测量,岩溶地下水、地表水和大气降水水化学和同位素特征分析,泉水流量动态,水均衡计算和物探等技术方法,系统分析了四川省康定市北郊碳酸盐岩分布区的岩溶发育特征,识别了岩...     

具有裂纹损伤的海底管道断裂及疲劳评估

海底管道是海洋石油开发的重要设施之一,对其进行断裂安全评估是非常重要的。介绍了结构失效评估图（FAD）技术,详细阐述了BS7910：1999规范中三个不同等级的断裂评估方法和疲劳评估方法。通过断裂评估方法,能够对不向受力状态下的含焊接裂纹管道进行断裂评估,得到管道任何位置的极限裂纹长度;通过疲劳评估方法,能够对受复杂动荷载的含焊接裂纹管道进行疲劳评估,得到管道在此种受力环境下的疲劳寿命。     

天然沸石对Pb(Ⅱ)和Ni(Ⅱ)离子的吸附作用研究

在静态条件下,研究了沸石对重金属离子（如Ｐｂ＾２＋和Ｎｉ＾２＋）的吸附与交换。结果表明,沸石对重金属离子具有较强的吸附性能,ｐＨ值的影响吸附的主要因素,离子交换和表面络合反应是主要吸附形式。