我国地下水质怎么了

2002年～2004年,“全国水资源综合规划项目”首次对我国平原地区地下水资源质量进行了系统而全面的评价:我国地下水水质趋向恶化。根据国家《地下水质量标准》进行的综合评价结果表明,在所评价的平原区面积中,Ⅰ类和Ⅱ类水质面积仅为5%,Ⅲ类区面积占评价面积的35.3%(Ⅰ类、Ⅱ类     

太湖原水水质指标分析与评价

太湖水是苏州市、无锡市的主要城市供水水源,本文调查分析了水源水厂2012年1月至2013年12月的部分原水水质数据指标,研究结果如下:太湖总体水质良好,基本达到地表水环境质量标准(GB3838-2002)III类标准。但存在部分指标部分时间段超标情况,尤其是原水中藻类含量偏高,常规工艺对藻类去除效果较差,因此,深度制水工艺需要强化对藻类的去除。     

“毒泉”揭秘

“边疆的泉水清又纯……”难道自然界中的泉水都像这首歌中唱得那样清澈、凉爽、甘甜吗？事实远非如此。我国泉的数量非常多,总数可以达到10万多处,分布十分广泛,种类也非常丰富,各地名泉不胜枚举。地下的泉水在地层经过漫长的旅行,往往形成了矿泉,有的对人有益,也有的受到各种污染,变得有毒有害。     

走进奇泉王国

五味泉江西永丰县有一眼神奇的泉,泉水具有麻、辣、酸、苦、甜五种味道。据分析,这是因为水中含有大量的碳酸气以及铁、铜、硅、锌、锰等十多种微量元素。泉水晶莹透澈,清凉可口,各项水质指标均符合饮用水的卫生标准。     

西藏农村生活饮用水微生物污染状况调查分析

目的：了解西藏农村生活饮用水微生物污染状况,为改善农村生活饮用水的卫生质量提供依据。方法：在拉萨市、山南地区6个县采集60份水样,依据国家标准方法进行检测和评价。结果：西藏农村生活饮用水微生物指标总合格率48．33％,其中细菌总数单项合格率为66．67％,总大肠菌群单项合格率为45．00％;地面水与地下水总的污染程度有显著性意义,地面水的总大肠菌群合格率高于地下水．地下水和地面水细菌总数污染差异无显著性;不同取水方式和供水方式对微生物污染影响不大无显著性意义。结论：西藏农村生活饮用水微生物超标,有导致肠道传染病暴发流行的安全隐患,政府应加快农村供水设施建设,加强对饮用水源的卫生防护,以保障农村居民饮水安全卫生。     

再生水补给河道周边水体特征——以北京潮白河顺义段为例

北京市再生水主要用于河湖补水,但再生水中污染物本底值较高,对周边水体产生了一定影响。本文基于2015—2017年北京潮白河顺义段再生水、地表水和浅层地下水的水位、水质监测数据,运用数理统计和水化学分析等方法,研究了再生水长期补给河道后周边水体的特征。结果表明：①受再生水水质影响,再生水补给河道的地表水总氮在所有监测点均出现超标;河道沿程氮、磷含量降低,pH值升高,夏季更为显著,与藻类光合作用和反硝化作用等因素有关。②周边浅层地下水水位稳定,仅存在季节变化;水化学类型以HCO₃·Cl-Na·Ca型为主,与再生水相似;140个水样中120个符合地下水Ⅳ类及以上标准,沿地下水流向水质有变好趋势;19个水样氨氮超标,主要出现在河南村橡胶坝附近,氮素可能来源于周边农、林地土壤氮素和灌溉施肥输入。③浅层地下水与地表水的主要水化学组分存在差异,与入渗过程中发生阳离子交换吸附作用和混合作用有关;河流渗漏影响到了距离河道中心约425 m的浅层地下水水质。本文可为进一步改善潮白河及其周边地下水水质和提高再生水利用率提供参考。     

延边州地下水资源开发利用情况分析

本文对延边州地下水资源的开发利用的基本情况、地下水水质现状及开发利用中存在的问题进行了论述,得出了地下水水质是地下水资源可持续利用的基本依据,是水资源保护工作的一个重要组成部分。水资源开发利用不但有水量的要求,更要有水质的保证。同时为保护地下水资源提出了相应的建议与措施。     

基于未确知的地下水资源承载力评价模型

地下水资源是很多地区经济发展的基础资源之一,合理对地下水资源进行开发、保护,做到可持续发展,是一项重要而艰巨的任务。因此,正确评价地下水资源的承载能力,对一个区域社会、经济的可持续发展、生态环境的良性循环和地下水资源的持续开发具有重要意义。     

浅谈地下水主要水质指标对饮用水供水质量的影响

本文论述了地下水的物理指标、含盐量、主要离子以及有毒物质等主要的水质指标对饮用水供水质量的不同影响,对地下水资源的正确评价和科学开发具有一定的参考意义。     

西藏满拉灌区水质分析与评价

为了评价西藏满拉灌区的河水和地下水的水质状况,在灌区内取了代表性水样进行试验分析,通过对试验数据分析研究,本区内水质良好,满足灌溉和工程要求。     

Students' Reactions to the Introduction of Videoconferencing for Classroom Instruction

This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors.     

Cooler temperatures inductive to locust outbreaks

Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007.     

Exploring Multiplexity: Social Network Structures in a Computer-Supported Distance Learning Class

A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction.     

Low doses of a red wine ingredient figh diabetes in mice

Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.     

The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong

Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies.     

How Electronic Publishers are Protecting Against Piracy: Doubts About Technical Systems of Protection

The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means.     

Rough Justice: A Statistical Assessment of ICANN's Uniform Dispute Resolution Policy

Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP.     

Prevalence of soft neurological signs in Chinese people

Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.     

Molecular motor assembly of a biomimetic system

Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction.     

Monoculture Rubber Plantations Have Negative Ef ects on Controlling Splash Erosion

<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence