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1.
森林与径流关系——一致性和复杂性   总被引:17,自引:1,他引:16  
@论文综述国外近一个世纪以来在配对集水区研究方面所取得的结论,从水的自然属性出发,从森林变化对径流(年径流量、洪峰与枯水径流)的影响,径流响应的干扰临界值及水文恢复各方面探讨森林变化与径流关系的一致性与复杂性。森林变化与径流关系的一致性主要表现在由较长时间尺度表达的年径流量上。绝大多数的配对集水区的试验研究表明,采伐森林就会增加年径流量,而在荒地上造林就会减少年径流量。而由较短时间尺度表达的洪峰径流与枯水流量则呈现较大的复杂性和难预估性。综述表明,对径流特别是洪峰与枯水径流的定义及分析方法的不同也是造成森林与径流关系复杂性的重要原因。森林与径流关系的复杂性要求人们在研究及应用其关系时就必须有系统观,必须考虑植被、径流与其它过程(土壤变化、气候变化等)的相互作用。论文还认为尽管配对集水区试验作为一种研究方法为研究者提供了许多可靠的结论,但由于许多研究者只把集水区看作是“黑箱”Q从而对认识森林与径流关系的复杂性有一定的局限性。未来的研究应把配对集水区的试验与其它对过程的研究技术(同位素、GIS等技术)结合起来。  相似文献   

2.
从雾和霾形成的原因以及与机动车尾气的关系等方面的论述,阐述了机动车尾气对人体健康的危害,提出了对机动车尾气的预防、治理办法。  相似文献   

3.
以某联合站为例,根据油气集输联合站站场功能,将联合站划分为油气处理、储运及污水处理3个单元,对各单元发生火灾爆炸事故的可能条件进行分析,并利用DNV公司的SAFETI软件对事故后果进行模拟计算,根据事故影响范围数据,提出相应的安全措施。  相似文献   

4.
The analysis of the ever-increasing amount of biological and biomedical data can be pushed forward by comparing the data within and among species. For example, an integrative analysis of data from the genome sequencing projects for various species traces the evolution of the genomes and identifies conserved and innovative parts. Here, I review the foundations and advantages of this "historical" approach and evaluate recent attempts at automating such analyses. Biological data is comparable if a common origin exists (homology), as is the case for members of a gene family originating via duplication of an ancestral gene. If the family has relatives in other species, we can assume that the ancestral gene was present in the ancestral species from which all the other species evolved. In particular, describing the relationships among the duplicated biological sequences found in the various species is often possible by a phylogeny, which is more informative than homology statements. Detecting and elaborating on common origins may answer how certain biological sequences developed, and predict what sequences are in a particular species and what their function is. Such knowledge transfer from sequences in one species to the homologous sequences of the other is based on the principle of 'my closest relative looks and behaves like I do', often referred to as 'guilt by association'. To enable knowledge transfer on a large scale, several automated 'phylogenomics pipelines' have been developed in recent years, and seven of these will be described and compared. Overall, the examples in this review demonstrate that homology and phylogeny analyses, done on a large (and automated) scale, can give insights into function in biology and biomedicine.  相似文献   

5.
真菌和细菌对染料的吸附脱色及再生能力的研究   总被引:9,自引:0,他引:9  
进行了真菌和细菌共培养对染料的吸附脱色和吸附脱色能力再生的研究。结果表明,青霉菌G-1首先对偶氮染料S-119、蒽醌染料艳紫KN-B(C.I.Reactive violet 22)水溶液中染料进行快速吸附去除,菌丝对同种染料的吸附速度随菌丝培养液中葡萄糖浓度的增加而加快,吸附染料的G-1菌丝在与细菌的共培养中完成对染料的脱色降解,脱色速度受培养液中葡萄和氮源浓度影响较大,从吸附速率和完全脱色时间综合评价,以葡萄糖浓度为5g/L、酒石酸铵为20mmol/L的培养基中培养的菌丝对染料的吸附脱色效果最好,吸附在菌丝上的艳紫KN-B脱色后菌丝吸附脱色能力得到再生,菌丝对100mg/L的艳紫KN-B染料水溶液可重复处理4次。青霉菌G-1对酸性染料废水处理3h,色度去除率为75.9%,吸附染料的菌丝在与细菌共培养中完成对染料的脱色,对试验所用染料废水,菌丝的处理能力获得1次再生。  相似文献   

6.
装置施工和检修中法兰、垫片的更换和选择   总被引:1,自引:0,他引:1  
文章对法兰、垫片泄漏对石油化工企业的安全、环保造成的威胁进行了分析,提出在设计中合理选用管道器材是保证管道和设备正常运行的关键。  相似文献   

7.
砷的污染、检测与防治   总被引:1,自引:0,他引:1  
在环境化学污染物中,砷是最常见、最严重的污染物之一.随着现代工农业生产的发展,砷对环境的污染日趋严重.为了更好地评价砷污染对环境和人体的影响,介绍了砷污染的来源、对人体的危害、标准的检测方法和目前砷污染治理的现状.  相似文献   

8.
A total of 2931 women randomized to either transabdominal CVS, transceirvical CVS, or amniocentesis were studied. Unless intended or unintended abortion had occurred, they had completed up to 28 weeks of pregnancy. No significant difference was seen between total fetal loss in the transabdominal CVS group and the amniocentesis group (6.5 and 6.8 per cent, respectively, SE difference = 0.92 per cent, p = 0.01). The total fetal loss in the transcervical CVS group was 10.1 per cent. After pooling our data with data from the Canadian randomized study and the American non-randomized study, the difference in risk between trans-cervical CVS and amniocentesis was 1.8 per cent (SE difference = 0.64 per cent, p = 0.8). When the number of failed procedures and those cases evaluated as infeasible for the assigned method-for anatomical reasons-are compared, the overall sampling efficacy is poorer transcervically than transabdominally.  相似文献   

9.
针对中小企业污染治理及投融资分析问题,本文阐述了中小企业的发展与环境污染现状,分析了中小企业在发展过程中所造成的环境污染问题,讨论了中小企业环境污染防治所面临的资金和技术的双重困境,剖析了中小企业环境污染防治的复杂特点,提出了中小企业污染治理的投融资建议,包括发行市政债券筹集治污资金和采用污染治理的市场化模式,建立中小企业污染治理的投融资机制,加快推进中小企业环境污染的治理,进一步完善中小企业污染治理和保障机制。  相似文献   

10.
立体种植与水土保持   总被引:3,自引:0,他引:3  
与自然相协调的立体种植,迁用于护堤、护岸、渠道衬砌和城市绿化,具有良好的保持水土作用,将其与生态开发相结合,会带来巨大的经济和社会效益。  相似文献   

11.
This paper draws ten lessons from analyses of adaptation to climate change under conditions of risk and uncertainty: (1) Socio-economic systems will likely respond most to extreme realizations of climate change. (2) Systems have been responding to variations in climate for centuries. (3) Future change will effect future citizens and their institutions. (4) Human systems can be the sources of surprise. (5) Perceptions of risk depend upon welfare valuations that depend upon expectations. (6) Adaptive decisions will be made in response to climate change and climate change policy. (7) Analysis of adaptive decisions should recognize the second-best context of those decisions. (8) Climate change offers opportunity as well as risk. (9) All plausible futures should be explored. (10) Multiple methodological approaches should be accommodated. These lessons support two pieces of advice for the Third Assessment Report: (1) Work toward consensus, but not at the expense of thorough examination and reporting of the "tails" of the distributions of the future. (2) Integrated assessment is only one unifying methodology; others that can better accommodate those tails should be encouraged and embraced.  相似文献   

12.
国内外产排污系数开发现状及其启示   总被引:9,自引:2,他引:7  
通过对国外产排污系数开发应用现状的系统分析,重点研究了美国产排污系数的基本特征、开发方法和途径以及遇到的障碍,结合我国产排污系数的开发现状和存在的问题,得出了对我国该领域研究的启示:建立产排污系数开发和管理的官方常设机构,定期发布最新数据;构建国家产排污系数信息管理平台;细化行业污染源分类,完善污染物种类;深入对产排污系数开发的理论体系和技术方法的研究,建立产排污系数核算方法学.指出了产排污系数不确定性评估研究将是未来重要的研究内容.   相似文献   

13.
土壤及果树中HCH和DDT残留及分布规律研究   总被引:5,自引:0,他引:5  
采用索氏提取、弗罗里土固相微萃取小柱净化结合GC-ECD测定了苹果园土壤和果树样品中4种六六六(HCH)和4种滴滴涕(DDT)的残留量,并对果树的根、枝、叶中HCH和DDT的分布规律进行了研究。实验结果表明,土壤和果树样品中均有HCH和DDT检出。土壤样品中两类农药的含量分别在0.51~3.97ng/g和1.46~15.55ng/g之间,其中β-HCH是六六六残留的主体,滴滴涕类的含量以p,p'-DDT为最高,并且(DDE+DDD)/DDT<1表明近期果园中有新的DDT输入。果树样品中,HCH和DDT的残留量分别在0.22~2.01ng/g和0.38~6.08ng/g之间,都要低于相应土壤中有机氯农药的浓度。果树中总OCPs的含量在4.88~17.94ng/g之间,是土壤和大气中OCPs污染共同作用的结果。根部的OCPs的含量明显高于枝和叶,其分布规律为根>叶>枝,这主要取决于根、枝、叶各组织的结构以及农药的理化性质。  相似文献   

14.
Cannabis is increasingly used for both medicinal and recreational purposes with an estimate of over 180 million users annually. Canada has recently legalized cannabis use in October 2018, joining several states in the United States of America (e.g., Colorado, California, and Oregon) and a few other countries. A variety of cannabis products including dry flowers, edibles, and oil products are widely consumed. With high demand for cannabis products worldwide, the quality of cannabis and its related products has become a major concern for consumer safety. Various guidelines have been set by different countries to ensure the quality, safety, and efficacy of cannabis products. In general, these guidelines require control of contaminants including pesticides, toxic elements, mycotoxins, and pathogens, as well as residual solvents in regard to cannabis oil. Accordingly, appropriate analytical methods are required to determine these contaminants in cannabis products for quality control. In this review, we focus on the current analytical challenges and method development for detection of pesticides and toxic elements in cannabis to meet various guidelines.  相似文献   

15.
基于在黄渤海的综合调查结果,分析了水体和沉积物间隙水中溶解无机氮(DIN)和溶解无机磷(DIP)的分布;结合历史数据构建了黄渤海DIN和DIP的收支模型,并分析了陆源输入变化对研究区域生态环境的影响.结果表明,黄渤海DIN和DIP的含量受季节、河流输入和沉积物界面扩散作用的影响,具有秋季高于春季和近岸高于离岸的时空分布特征.收支模型计算结果表明,底界面扩散是黄渤海水体DIN的主要来源,其次是大气、周边河流、地下水和东海的输入;黄渤海水体DIN的支出主要是通过沉积埋藏和反硝化.黄渤海水体DIP的来源主要是磷酸盐吸附解吸,占91%,底界面扩散和大气输入为其次,河流和地下水的输入贡献较小.DIP的支出主要是通过沉积埋藏和向东海的输出.黄渤海每年有11Gmol的氮在水体积累,并导致其浓度提高约0.6μmol/(L·a).近些年来陆地向黄渤海输入氮的持续增加,加剧了氮营养盐的积累,导致非硅藻类浮游植物比例以及赤潮发生频率和面积显著增加,同时还提高了水体初级生产力和海洋磷的埋藏量以及加剧了磷限制的趋势,并可能威胁生态系统的稳定.  相似文献   

16.
“一带一路”沿线国家水资源禀赋及开发利用分析   总被引:2,自引:2,他引:0  
水资源是基础性的战略资源,开展“一带一路”沿线国家水资源研究对于促进“一带一路”的科学建设具有重要意义。基于世界银行与联合国粮农组织水资源数据库,从水资源开发利用角度入手,分析“一带一路”沿线国家水资源自然禀赋、利用状况,在此基础上进一步分析水资源开发潜力。结果表明:(1)从水资源禀赋来看,“一带一路”沿线国家地表水、地下水和水资源总量均以俄罗斯、中国、东南亚和南亚地区相对较高,中亚、西亚等地区相对较低;人均水资源量则以中东欧、俄罗斯和东南亚地区较高,西亚、南亚地区较低;“一带一路”沿线国家外来水依赖率整体表现为跨境河流下游高,上游及海岛国家低。(2)就水资源利用而言,“一带一路”沿线国家用水量整体呈现“东多西少”的格局,人均用水量表现为“中亚最高,周边较低”的特点;用水结构亚洲国家多以农业用水为主,中东欧国家则多以工业用水为主。(3)水资源开发潜力分析发现,阿拉伯半岛地区各国水资源开发潜力很低,中东欧及东南亚地区水资源开发潜力很高。  相似文献   

17.
18.
持久性、迁移性、毒性或高持久和高迁移性化学品(PMT/vPvM)在全球地表水、地下水和饮用水水体已被广泛检出,是未来可能显著影响人类健康和环境的一类重要新兴污染物.按照欧盟提议的鉴别标准,现有化学品中的PMT/vPvM数以千计,涉及用途广泛,包括三聚氰胺等数10种较高产量的工业化学品.PMT/vPvM可通过农田径流、工业废水和生活污水排入环境,污水处理厂目前被认为是其主要排放途径.因难以被现行常规水处理技术有效去除,PMT/vPvM可长期存在于城镇人居环境水循环系统中,危及居民饮用水及生态系统安全.欧盟已率先开始将PMT/vPvM专门纳入现行化学品风险管理体系中的优先范畴.目前,环境中仍有众多潜在PMT/vPvM,其监测方法亟待进一步完善,物质鉴定、类别范围及清单建立均尚需时日;PMT/vPvM在全球各地区的环境分布和暴露研究十分有限,其潜在、长期的生态毒性和人体健康危害效应研究较为匮乏.与此同时,替代品或替代技术以及污水处理、污染场地修复等环境工程治理技术的研究和开发,都将成为未来PMT/vPvM风险科学研究与管理决策的迫切需求.  相似文献   

19.
《黑龙江环境通报》2014,(4):106-110
阴阳观念与古代文学的关系密切。在文学创作方面,阴阳对举、"物生有两"、"惟两能化"的宇宙发生观,导致了古代文人重视骈丽的创作倾向,是古代骈文发生发展及古代文学语言形式普遍骈化的深层文化原因;在文学的变化方面,"物生有两"、"惟两能化"的自然变化观,导致了古人以天道自然变化以解释文学发展变化的现象,形成了以刘勰为代表的"质文代变,变不失常"文学发展观;在文艺的审美方面,阴阳交感、、刚柔相济、得中为吉的万物根本论,导致了古人普遍以"中和"为美的现象,使"中和"美论成为古代几千来的审美主潮。  相似文献   

20.
科学技术对生产力发展的巨大作用。不仅表现在它对生产力3个要素的渗透性影响。而且表现在它促进生产力结构的优化和系统功能的发挥,但经济发展会带来资源破坏和环境污染等负面影响。应在发挥科技作为第一生产力作用的同时,遏制其带来的负面影响,以促进可持续发展。  相似文献   

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