首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 140 毫秒
1.
秋色叶树种在园林造景中的应用   总被引:3,自引:0,他引:3  
秋色叶树种是园林造景中重要的观赏树种之一,我国秋色叶树木资源十分丰富,开发利用秋色叶树木资源对我国园林建设具有重要意义.作者分析了秋色叶树种内涵,主要树种的性状、特征、观赏价值及在我国自然秋色景观中的应用等,初步探讨了它们在城市园林造景中应用方式、应用前景,提出了秋色叶树种选择应用的原则及应注意的问题.  相似文献   

2.
本文简要介绍了概率稀释模型的理论基础及其改进方法,以肥城市康汇河为例,应用该模型确定了河流污染物各总量控制方案下的水质目标及其达标率,阐明了该模型在水体污染物总量控制中的应用。  相似文献   

3.
含砷废水净化剂的制备及其应用研究   总被引:1,自引:0,他引:1  
本文描述了用黄铁矿和还原铁粉或其代用品为原料制备含砷废水净化剂-硫化亚铁的新方法,获得了制备的最佳条件,探讨了其在含砷废水处理中的应用条件和影响因素,结果表明,该净化剂的生产及其处理含砷废水的工艺简单,经济高效,具有良好的开发应用前景。  相似文献   

4.
根据京郊菜田的分布和土壤养分、土壤环境质量特点选择了监测点,按照各个指标对土壤质量的影响程度确定评价指标及其权重,并据此建立了无公害菜田土壤环境评价系统。系统采用分层体系结构,在目前基于J2EE架构开发Web应用的基础上,采用J2EE中的JSP,Servlet,JavaBean以及JDBC技术来构建该平台的基础组件框架,结合MVC结构的方式来构建Web应用系统,有效地提高了应用程序的可重用性、可维护性和可扩展性。根据过去3年的监测结果对于系统进行了初步应用,对各个监测点的菜田土壤环境质量进行了评价,表明该评价系统对菜田环境质量管理具有很好的指导意义。  相似文献   

5.
我国稻鸭共作生态农业的发展现状与技术展望   总被引:20,自引:0,他引:20  
综述了目前稻鸭共作技术在我国各地试验研究与示范应用的现状,提出了在今后研究与应用中需要探讨与完善的几个方面,包括:鸭子选用、防护与鸭病防治,水稻栽插方式及配套农机要求,施肥制度与病虫防治,以及稻田生态效应与高效种养模式。  相似文献   

6.
高分子材料被广泛地应用在社会生活的各个方面,但其易燃性往往容易引发火灾,造成巨大的生命财产损失.利用阻燃剂改性是提升高分子材料防火阻燃性能的有效方法之一,其中生物基阻燃剂由于具有原料易得及绿色环保等特性,成为近年来阻燃剂研究领域的前沿热点之一.本文首先介绍了近年来几种主流的生物基阻燃剂的合成方法,随后介绍了其他应用较少的生物基阻燃剂以及全生物基阻燃剂的发展情况,并对生物基阻燃剂的应用及其面临的问题展开讨论.最后,展望了生物基阻燃剂未来的发展趋势.  相似文献   

7.
实时控制技术在污水生物处理中的研究进展   总被引:2,自引:0,他引:2  
针对目前污水处理厂采用固定时间控制策略所暴露出的问题,从污水生物处理反应机理上分析了溶解氮(DO),氧化还原电位(ORP)和pH值作为污水生物处理实时控制参数的可行性,得出污水处理过程中反应器内DO,ORP和pH的变化可以间接反应有机物降解和脱氮除磷过程,因此,在理论上可以应用DO,ORP和pH作为实时控制参数控制污水处理过程,综述了当前国内外应用DO,ORP和pH作为实时控制参数控制污水处理过程的研究进展,并分析了目前我国在此研究方向存在的问题,指出进一步加强对污水处理实时控制技术应用基础研究的必要性和紧迫性,并使其与智能控制技术相结合,最终实现污水处理自动化,参27  相似文献   

8.
天然水体沉积物对重金属离子的吸附特性   总被引:38,自引:0,他引:38  
杜青  文湘华 《环境化学》1996,15(3):199-206
本文运用表面络合模式,研究了江西乐安江下游黄龙庙沉积物的吸附特性,测定了样品对重金属CU,cD的吸附等温线和PH吸附突跃曲线;应用FITEQO程序计算了沉积物的表面固有吸附常数;对恒定容量模式,扩散层模式和三层模式在天然水体沉积物中的应用进行了比较。  相似文献   

9.
饮水除氟剂的应用   总被引:9,自引:0,他引:9  
黄衍初  姜兆春 《环境化学》1994,13(6):561-567
本文对国内饮水除氟剂的研究和应用现状进行了综述,对常用絮凝剂和滤料的除氟性能、适宜条件及应用情况进行了简要比较,同时对近期研制和生产的新除氟剂,如CF-1,PC85-3,6210,以及新型除氟滤料,如GT,SBC,CF型微型过滤管、蛇纹石、UR-3700螯合树脂等的除氟效果进行了讨论。  相似文献   

10.
微生物絮凝剂的研究与应用进展   总被引:50,自引:0,他引:50  
微生物絮凝剂是具有广阔应用前景的一种天然高分子絮凝剂,因而引起科学界的高度重视.自70年代以来,美国和日本等十多个国家已对其进行了详细的研究.本文综述了微生物絮凝剂的研究与应用进展,包括合成絮凝剂的微生物种类、微生物絮凝剂的化学本质、遗传基础和微观结构、微生物絮凝剂的絮凝机理和絮凝能力及其影响因素,微生物絮凝剂的合成条件和提取方法等方面.文中还给出了微生物絮凝剂在污染治理等领域实际应用的若干事例.  相似文献   

11.
Nature reserves have developed rapidly over the decades in China and play a significant role in the function of ecosystem services. The function of ecosystem services in nature reserves, however, has tended to decline in recent years due to natural hazards and human activities. Based on land use, the variation of ecosystem services value (ESV) during 2000–2010 in national nature reserves in Sichuan was evaluated. We analyzed the comprehensive effects of natural disasters and human activities on the decline of ESVs. Total ESV in the national nature reserves in Sichuan was approximately 2741.35 million US$ in 2000, 2616.81 million US$ in 2005, and 2499.06 million US$ in 2010, representing a decrease of 242.29 million US$, or 8.84%, in the decade. Forestland, grassland, wetland, and water bodies played vital roles in the function of ecosystem services, with an aggregated ESV of 99% of the total. The largest proportion of the total ESV was the protection of biodiversity at 48.6%. ESV of all land use types and single ecosystem services continued to decline during 2000–2010. A mechanism of adaptable risk prevention should be established, and unreasonable human activities should be avoided to protect ecosystems and to improve the functions of ecosystem services.  相似文献   

12.
Predation risk has been shown to alter various behaviours in prey. Risk alters activity, habitat use and foraging, and weight decrease might be a consequence of that. In mammals, studies on physiological measures affected by risk of predation, other than weight, are rare. We studied in two separate laboratory experiments foraging, hoarding behaviour and expression of stress measured non-invasively from the faeces in the bank vole (Clethrionomys glareolus), a common boreal rodent. Voles were exposed to predation risk using odours of the least weasels (Mustela nivalis nivalis). Distilled water served as control. In the first experiment, we found that foraging effort, measured as sunflower seeds taken from seed trays filled with sand, was significantly lower in trays scented with weasel odour. Both immediate consumption of seeds and hoarding were affected negatively by the weasel odour. Females hoarded significantly more than males in autumn. In the second experiment, the negative effect of weasel odour on foraging was consistent over a 3-day experiment, but the strongest effect was observed in the first night. Foraging increased over the time of the experiment, which might reflect either energetic compensation during a longer period of risk, predicted in the predation risk allocation hypothesis, or habituation to the odour-simulated risk. Despite decreased foraging under predation risk, stress measured as corticosteroid metabolite concentration in vole faeces was not affected by the weasel odour treatment. In conclusion, we were able to verify predation-risk-mediated changes in the foraging effort of bank voles but no physiological stress response was measured non-invasively, probably due to great individual variation in secretion of stress hormones.  相似文献   

13.
The new institution of comprehensive high school, in Greece today, aims to relate the school with the natural, social, economical and cultural environment. In this frame of process, interrelation and dynamic contact of school with the holistic environment, the subject “Ecology and Environment”; of the 2nd class (16–17 years old), informs, sensitizes and activizes the anxious young generation. The textbook of the subject determines and analyzes the human impact and their consequences to the natural ecosystems. In the total content there are also numerous examples from the natural, man‐made and cultural environment of Greece.  相似文献   

14.
中国公众参与环境管理的研究   总被引:18,自引:0,他引:18  
回顾了中国公众参与环境管理的发展历程,分析了公众参与环境管理存在的问题。针对公众参与环境保护管理的有效性的影响因子,例如主观因素、传统背景、时效因素及执行技巧等进行一系列的探讨,并根据公众参与计划的设计构思、公众参与计划的关键两方面的讨论,提出增加公众参与环境保护管理有效性的一些建议。  相似文献   

15.
The mineral elements present in brown rice play an important physiological role in global human health. We investigated genotypic variation of eight of these elements (P, K, Ca, Mg, Fe, Zn, Cu, and Mn) in 11 different grades of brown rice on the basis of the number and distance coefficients of 282 alleles for 20 simple sequence repeat (SSR) markers. Six-hundred and twenty-eight landraces from the same field in Yunnan Province, one of the largest centers of genetic diversity of rice (Oryza sativa L.) in the world, formed our core collection. The mean concentrations (mg kg−1) of the eight elements in brown rice for these landraces were P (3,480) > K (2,540) > Mg (1,480) > Ca (157) > Zn (32.8) > Fe (32.0) > Cu (13.6) > Mn (13.2). Mean P concentrations in brown rice were 6.56 times total soil P, so the grains are important in tissue storage of P, but total soil K is 7.82 times mean K concentrations in brown rice. The concentrations of the eight elements in some grades of brown rice, on the basis of the number and distance coefficients of alleles for 20 SSR markers for the landraces, were significantly different (P < 0.05), and further understanding of the relationship between mineral elements and gene diversity is needed. There was large variation in element concentrations in brown rice, ranging from 2,160 to 5,500 mg P kg−1, from 1,130 to 3,830 mg K kg−1, from 61.8 to 488 mg Ca kg−1, from 864 to 2,020 mg Mg kg−1, from 0.40 to 147 mg Fe kg−1, from 15.1 to 124 mg Zn kg−1, from 0.10 to 59.1 mg Cu kg−1, and from 6.7 to 26.6 mg Mn kg−1. Therefore, germplasm evaluations for Ca, Fe, and Zn concentrations in rice grains have detected up to sevenfold genotypic differences, suggesting that selection for high levels of Ca, Fe, and Zn in breeding for mass production is a feasible approach. Increasing the concentrations of Ca, Fe, and Zn in rice grains will help alleviate chronic Ca, Zn, and Fe deficiencies in many areas of the world.  相似文献   

16.
A cost of mating is common to both sexes but has predominantly been examined in females. In species where males provide resources to females at copulation, male mating costs are expected to be high as nutrient provisioning enhancing female fecundity is assumed to carry costs. In addition, males frequently court females prior to mating, which is known to carry survival costs to both sexes. However, the magnitude and basis of variation in males’ mating costs remains largely unknown. Here, I examine the effect of nutrient provisioning and courtship on male longevity across full-sib families in the paternally investing green-veined white butterfly, Pieris napi. Copulating males suffered a survival cost as did courting males prevented from copulating, indicating the courtship component of mating is costly. Male P. napi release aphrodisiacs during courtship to promote mating, indicating that these compounds may also be costly to produce. Contrary to expectation, nutrient provisioning was not associated with reduced survival relative to males only allowed to court females, although it is possible that this could be masked by the potentially elevated courtship rates of courting males relative to mating males. Families differed in magnitude of reduced male survivorship, indicating a likely genetic basis to variation in costs of courtship and copulation. Male weight was unrelated to longevity and mating success, whereas longevity strongly influenced male mating success, indicating lifespan is an important male fitness trait in this species.  相似文献   

17.
长春市主要蔬菜中农药残留分析   总被引:11,自引:1,他引:11  
采用速测法和气相色谱法研究了长春市市场销售的主要蔬菜中的农药残留问题。2002年秋季对长春市的9个蔬菜批发市场的16种蔬菜进行抽样检测,蔬菜中有机磷类和氨基甲酸酯类农药平均超标率为11.05%,残留的主要农药种类是甲胺磷、氧化乐果和敌敌畏。检测16种蔬菜中有9种超标。2003年春季同样对9个蔬菜市场的17种蔬菜进行抽样检测,农药残留平均超标率为11.0%,残留的农药主要种类是甲基对硫磷、对硫磷、甲拌磷、敌敌畏、氯氰菊酯和氰戊菊酯等,检测的17种蔬菜中有3种严重超标。由此可见蔬菜中农药残留还是很严重的问题,政府与有关部门仍需加强管理。  相似文献   

18.
镇江内江湿地植物群落演替过程中土壤养分动态研究   总被引:6,自引:0,他引:6  
镇江内江湿地是由长江携带的泥沙在镇江内江特有的水文条件下淤积而成,形成于江滩裸地上的植物群落开始了群落的原生演替过程。在此过程中,湿地的土壤养分状况随着植被的演替更迭,发生着协同演化的过程。为了进一步丰富群落演替理论,通过研究群落演替过程中不同阶段以及同一演替阶段不同层次土壤养分状况的时空变化,探索演替过程中的不同植被类型和土壤养分变化的内在联系及其互作效应。结果表明,随着演替进行,土壤的养分状况趋于改善,土壤有机质、全氮和速效磷含量呈上升趋势,只有速效钾的含量在后期芦苇阶段明显降低,这主要是由于收割芦苇将富含钾素的芦苇植株带出湿地系统所致。由于植物根系分布及枯落物多少的差异,使得各营养成分的垂直分布各异。  相似文献   

19.
三江平原农田源头排水沟渠截留排水中氮素动态   总被引:1,自引:0,他引:1  
通过小尺度野外原位试验,研究排水沟渠水体、底泥和植物中氮含量的变化规律.结果表明,随水体停留时间增加,沟渠对水体氮素的净化能力增强,认为停留8d左右较适宜.沟渠对NH4-N的截留率大于TN和NO3--N.渠水停留11d时,4条试验沟渠[氮浓度高、磷浓度低(NHPL),氮浓度高、磷浓度高(NHPH),氮浓度低、磷浓度低(NLPL),氮浓度低、磷浓度高(NLPH)]对NH4+-N的截留率均达100%,对NO3--N的截留率分别为84.63%、84.35%、75.67%和76.14%,对TN的截留率分别为88.02%、89.89%、90.88%和88.53%.试验结束时沟渠表层(0~15 cm)底泥氮含量降低,植物氮累积量远大于进水TN总量,说明植物生长同时吸收了水体、土壤和底泥中的氮,建议在秋季适时收割植物,以避免植物分解导致二次污染.  相似文献   

20.
The background levels of lead in Jamaica in soils and sediments, estimated at 37 mg kg–1, are relatively high compared with world averages. Several areas have values in excess of this due to mineralisation and pollution. One such is the residential Hope Flats/Kintyre area in which levels of lead up to 2.5% are found in the soils and up to 8 g kg–1 in the water of the nearby Hope River. The blood lead levels of a sample of children were in the range 5.7–57 g dl–1. The high lead levels suggest a potential health risk, particularly for the children. This can be minimised by programmes which include community education, case management and abatement to reduce the lead exposure.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号