应力触发,应力影响及其对地震危险性的意义

在２０世纪即将结束的时候,地震力学研究的许多方面仍留下疑团,留下一线光明的是我们已认识到对应力变化的简单计算可以解释一些地震之间的相互作用,并可以用以往的和正在进行的应力变化研究来解释人工诱发的地震活动。     

外源污染物对硬骨鱼甲状腺干扰作用机制的研究进展

甲状腺激素在鱼类生长发育、变态、生殖、渗透调节以及摄食和营养代谢中发挥着重要作用,外源化合物对硬骨鱼的甲状腺干扰作用会导致发育和孵化延迟、运动性降低。本文首先对鱼类甲状腺激素的中枢调控、合成、转运、代谢和发挥作用的相关过程进行简要介绍,随后从核受体介导途径、非受体介导途径两个方面综述了外源污染物对硬骨鱼甲状腺的干扰作用机制,最后从物种特异性、检测指标、膜受体介导途径三个方面提出了目前研究的不足之处以及解决方法,以期为今后探究外源污染物对鱼类甲状腺系统干扰作用机制的研究提供更多的参考。     

上海市海洋环境监测现状研究

上海市海域开发利用强度大,海洋环境形势不容乐观。2009年机构改革后,上海市探索陆海统筹的管理新体制,海洋环境监测工作逐步发展。文章总结了上海市海洋环境监测现状,分析存在的主要问题是监测体系不够健全、近岸海洋环境污染形势严峻、危化品风险源监管不足、有机污染物环境本底不清,以及对外来生物入侵重视不足等,并对未来发展提出了针对性建议,建议尽快完善监测体系,优化监测布局,提高有效应对突发事件的能力,以便更好地服务于海洋环保事业。     

松辽盆地东南部油气、煤层气后生蚀变硫同位素特征

对松辽盆地东南部上白垩统泉头组、姚家组和嫩江组岩石中黄铁矿及硫同位素特征研究表明,泉头组、姚家组中后生还原褪色作用形成的灰色、灰绿色砂岩中的黄铁矿及硫同位素均显示出了深部来源的油气、煤层气有机流体作用成分特征。该区原生沉积成岩岩石及黄铁矿中硫同位素的δ^34SV-CDT为正值,油气、煤层气有机流体还原作用岩石及黄铁矿中δ^34SV-CDT为负值。油气、煤层气还原作用不仅使杂色、紫红色原生氧化砂岩还原为灰色、灰绿色还原性砂岩,还使岩石还原容量大大增强,而且油气、煤层气在有机流体与岩石的相互作用过程中有铀的叠加富集,岩石铀含量普遍增加,局部可形成铀异常、铀矿化。首次在门达地区姚家组含矿砂岩中发现网脉状水云母化,显示铀成矿具有低温热液蚀变特征,铀矿化与低温热流体作用有关。     

Using existing data to estimate aquifer properties, Great Lakes Region, USA

To determine specific storage and porosity, areally limited and time-consuming aquifer tests are frequently done. Hydrogeologic studies often do not have the resources to collect such data and rely on existing data sources for aquifer properties. An alternative tool for determining these aquifer properties is the analysis of earth tides. The objective of this study was to determine whether existing water-level and barometric-pressure data could be used to determine aquifer properties, such as porosity and specific storage, on a regional scale. In this study, national databases from the Great Lakes Region were queried for continuous records of groundwater-level and barometric-pressure data. Records from 37 selected wells were then analyzed for barometric efficiency and earth-tide responses. Specific-storage (S(s) ) and porosity values were determined, and the quality of the results were assessed with a measure of the "goodness of fit" (percent variance) of reconstruction of the response. Records from wells completed in several aquifer systems were analyzed with varying degrees of success. Aquifer S(s) values ranging from 5.9 × 10(-8) to 3.8 × 10(-6) /m were derived, with percent variance of reconstruction ranging from 1% to 78%. Comparisons with aquifer and laboratory testing of S(s) and porosity are favorable if the percent variance of reconstruction is above about 30%. Although the earth-tide-analysis method is not suitable for every situation, the S(s) and porosity of aquifers can, in many places, be estimated with existing water-level and barometric-pressure data or with data that are relatively inexpensive to collect.     

鱼类甲状腺轴对胚胎发育、仔鱼变态及性别分化的调控作用研究进展

鱼类甲状腺轴由下丘脑、垂体、甲状腺组成,下丘脑通过分泌促甲状腺激素释放激素、促肾上腺皮质激素释放激素调节垂体促甲状腺激素的合成和分泌,促甲状腺激素促进甲状腺滤泡合成并释放甲状腺激素(主要为甲状腺素—T4),T4运输至肝脏等外周组织中,经过脱碘转化形成生物活性更强的三碘甲腺原氨酸(T3),T3主要通过同核受体结合发挥生物学功能。甲状腺激素对鱼类胚胎发育、仔鱼变态及性别分化等早期生长发育过程具有重要调控作用:甲状腺激素为鱼类胚胎发育期所必须,外加适量甲状腺激素能够提高胚胎或仔鱼存活率;仔鱼变态过程中,某些外部形态变化及相关组织分化依赖甲状腺激素的调控,牙鲆等仔鱼变态期体内甲状腺激素水平及其受体表达量会显著升高;性腺发育期,甲状腺激素对调控鱼类性别分化方向可能具有一定作用。     

黄土-红层接触面滑坡稳定性可靠性分析

针对黄土-红层接触面滑坡存在的变异性、随机性、不确定性,为了充分考虑其影响因素,利用Monte Carlo法的基本原理,结合传递系数法建立滑坡稳定性可靠性分析的状态功能函数,从而得到以失稳概率Pf和可靠性β为指标的滑坡稳定性可靠性分析结果。以天水-陇西滑坡密集带中典型的黄土-红层接触面滑坡为例,通过现场勘察、室内实验、理论分析等,分析了滑坡基本特征、岩土体性质以及影响因素。在分析滑坡形成机制的基础上,统计分析滑带土黏聚力c、内摩擦角φ得到其均值、标准差、变异系数、分布规律等,借助VC++程序设计,从而计算得到该滑坡失稳概率和稳定性可靠性。由分析结果可知,该方法得到的滑坡稳定性与传统稳定性分析方法基本一致;该方法从多角度、多指标综合分析了滑坡稳定状态,提高了滑坡稳定性评价精度。      

巢湖北部耙子山-马家山区域断裂构造演化特征研究

巢湖北部的耙子山-马家山区域,由于不同时期不同性质的构造相互叠加,呈现出相对复杂的地质构造现象。研究认为：该区主要经历了印支、燕山两期构造运动,多期次构造运动相互干扰、相互叠加,从而形成了复杂多变的断裂构造演化特征。     

Estrogen pollution in a highly productive ecosystem off central-south Chile

While the presence of steroid estrogens in the environment has become a major environmental and health concern, their occurrence in coastal sediments remains poorly characterized. In this study, we measured the levels of three natural (estrone, 17β-estradiol, estriol) and one synthetic (17α-ethinylestradiol) estrogens in 54 coastal sediment samples collected from nine locations off central-southern Chile. Steroid estrogens were found in every sample. Remarkably high levels of 17α-ethinylestradiol were detected, reaching up to 48.14 ng/g dry weight. As a result, the global estrogenic loads were estimated to be high at all sites. Interestingly, they were found to correlate with the size of human populations served by sewage plants. Our study indicates that 17α-ethinylestradiol may accumulate in coastal sediments. The possible impact of this highly potent synthetic estrogen on the biota of the marine ecosystem off central-south Chile and on human health remains an open question.     

Comparison of coral growth and survival under enclosed,semi-natural conditions and in the field

Two closely related scleractinian coral species, Porites cylindrica and Porites rus, were transplanted to two different locations: the natural environment on the reef flat, and culture tanks on land. The use of tanks enabled the regulation of certain environmental factors, and, hence, the evaluation of specific responses of the corals to these factors. For both species, growth and survival were much better in the field than in the land-based tanks most probably due to unrestricted water circulation. Since the two species were subjected to identical experimental treatments, it was possible to distinguish inherent differences between them in terms of responses to external variables. Porites cylindrica was more susceptible than P. rus to predation by corallivores. Predators, as well as grazers, occurred in significant numbers in the field, but not in the land-based tanks. Porites rus, on the other hand, succumbed more readily to overgrowth by macroalgae which thrived in the culture tanks presumably because of significantly higher nutrient levels and the conspicuous absence of grazers. These results have broader ecological implications because of accelerated environmental changes taking place in present-day reefs due to human impact. Major examples are eutrophication and alterations in water circulation which frequently result in sub-optimal conditions for coral survival and growth.