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1.
丽蝇蛹集金小蜂(Nasonia vitripennis walker)是膜翅目的一种寄生性昆虫,其幼期阶段寄生于蝇蛹体内,取食蛹内组织,起到灭蝇作用。该蜂在寄主蝇蛹内进行胚胎期、幼虫期和蛹期各阶段的发育。蜂卵孵化出幼虫,经过三个龄期、预蛹与蛹再羽化出成蜂啮破蝇蛹壳而出,整个过程都是在寄主蝇蛹内进行。羽化出的成蜂再交配、寻找寄主、产卵寄生。因此,作者认为丽蝇蛹集金小蜂的寄主蝇蛹就是该蜂生长发育的微生态环境(Microen vironment)。蜂幼并在寄主蝇蛹内越冬,所以,蝇蛹自然成为蜂幼虫越冬的微生态环境。关于丽蝇蛹集金小蜂的生物学与生态习性的研究报告很多,但对该蜂的微生态环境及其对个体发育的影响报告很少。对该蜂微生态环境及其对个体发育的影响研究有助于其生物学与生产实践利用的探讨。作者于1984年4月至1985年12月对该蜂的微生态环境及其对个体发育的影响进行了初步研究,现报告如下。  相似文献   

2.
从1775年至今,美国医药产业经历了从萌生到成熟的百年历程。其早期发展受战争的影响非常大,后期发展受制度影响较大,医药产业的发展与监管法规相辅相成。从历史的角度对美国医药产业发展历程进行系统梳理,并尝试将其划分为5个阶段:孕育期(1775—1860年)、诞生期(1861—1869年)、起步期(1870—1929年)、发展期(1930—1983年)和高新期(1984年—至今)。通过此项研究,勾勒出美国医药产业各个历史阶段的主要特点,以期更好地总结美国医药产业发展经验,为中国医药产业发展提供借鉴。  相似文献   

3.
【目的】本研究旨在明确湿度变化对梨小食心虫Grapholitha molesta(Busck)在果实外各阶段存活率和蛀果率的影响及湿度对害虫最终存活率产生影响的关键阶段。【方法】在室内相对湿度25%,40%,55%,70%和85%条件下,记录和分析梨小食心虫的产卵量、卵孵化率、幼虫蛀果率、老熟幼虫化蛹率、蛹羽化率以及产卵、化蛹和羽化时间。【结果】湿度高低对化蛹率没有影响,供试的5种相对湿度下,化蛹率均为100%;但湿度对产卵量、卵孵化率、幼虫蛀果率、蛹羽化率和世代存活率均有显著影响,湿度越高,各阶段存活率、幼虫蛀果率和世代存活率也越高。不同虫态存活对湿度要求从高到低依次为:幼虫蛀果期成虫期卵期蛹期老熟幼虫期。湿度对害虫世代存活率产生显著影响主要发生在幼虫蛀果期、成虫期和卵孵化期。同时,湿度提高利于成虫产卵、化蛹和羽化,反之发育延缓。【结论】湿度会显著影响梨小食心虫各阶段的存活率、幼虫蛀果率和繁殖,成虫盛发期、卵期和蛀果期的湿度影响害虫种群数量和蛀果率的关键阶段。  相似文献   

4.
新石器文化与全新世生态环境变化的关系是学术界关注的热点问题。通过对筛选出的中国典型地区孢粉记录的生态环境和具有年代数据考古遗址的综合分析,初步认为:1)典型地区全新世生态环境变化与新石器文化之间具有较密切的关系,中全新世温暖湿润期的生态环境宜于这一时期的文化发展; 2)东亚季风是影响典型地区新石器文化发展的重要因素之一;不同地区的地形和水位在一定程度上也影响了区域文化的发展; 3)约4.3~4.2 ka BP的全球事件在典型地区表现明显,太阳辐射减少和东亚冬夏季风的变化可能是影响典型地区生态环境变化和新石器文化衰退乃至消失的主要因素; 4)高分辨率孢粉记录的生态环境、考古遗址的系统测年、生态环境与文化发展的耦合机制等是未来需要深入研究的方向。  相似文献   

5.
何志远  杨振凯  丁志伟  王世鹏  李晗 《生态学报》2024,44(12):5040-5058
城镇化与生态环境协调平衡是提升城市品质的重要举措,也是推进新型城市建设的内在要求。基于构建的城镇化与生态环境系统综合评价指标体系,引入耦合协调模型对2010-2020年中国市域城镇化与生态环境系统的耦合协调度进行测度并分析其影响因素。结果表明:(1)从空间分布格局来看,城镇化发展水平整体呈现京津冀、长三角、珠三角地区领先,成渝、中部地区中等,西南、西北地区相对落后的分布特征;生态环境建设水平呈现出"南高北低,多点开花"的分布特征。(2)从空间关联格局来看,城镇化发展水平和生态环境建设水平皆呈现明显的集聚现象,且以HH、LL区分布为主。其中城镇化发展水平显著LL区主要在西部地区集中分布,大范围低值集聚态势明显,反映出该地区城镇化有待进一步发展;生态环境建设水平显著HH区主要在东南地区集中分布,显著LL区主要在西部和东北地区,反映出广大西部和北方地区的生态环境欠佳。(3)从耦合协调度来看,两大系统之间的磨合作用持续向好,轻度失调及以下协调发展类型的城市数量不断下降,整体迈入转型发展阶段。在空间分布上东部沿海地区整体的耦合协调度水平高于内陆地区。从城镇化与生态环境耦合协调关系看,在研究期总体上呈均衡发展状态,但是有向生态环境滞后型发展趋势。在空间分布上呈南-北差异化格局,2020年生态环境滞后型南北方城市之比为4 ∶ 6。(4)从影响因素看,城镇化状态、城市和谐状态、城市总体生态状况、城市对生态环境治理投入程度、城市绿色低碳建设程度以及水资源利用情况这几个方面均有重要解释作用。  相似文献   

6.
关健飞  曹阳  徐鸿嘉 《生态学报》2024,44(13):5726-5734
冻土微生物对预测冻土和气候之间潜在反馈机制至关重要。为明确不同冻融阶段对冻土细菌群落的影响,揭示冻土性质变化与细菌群落之间的响应关系,选择黑龙江典型季节冻土表层土为研究对象并进行理化性质测定,采用16S rRNA高通量测序技术分析细菌群落结构和功能组成,通过冗余分析等方法探究土壤理化性质与细菌群落结构和功能之间的相关关系。结果表明:(1)不同冻融阶段对土壤pH和总磷含量影响不显著,完全冻结期土壤中机质和总氮含量显著高于冻融循环期(P < 0.05)。(2)共获得OTU序列985111条,属于42个菌门,优势菌门中,放线菌门(Actinobacteria)相对丰度在完全解冻期显著高于冻融循环期和完全冻结期(P < 0.05),变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)相对丰度在不同冻融阶段未表现出显著性差异。不同冻融阶段对细菌Alpha多样性和Beta多样性影响显著,其中冻融循环期显著增加了细菌群落的多样性,完全冻结期则使Beta多样性发生显著变化。此外,完全冻结期对细菌丰度之间的正相关性以及群落的稳定性影响较大。(3)细菌群落功能共5418种,分属于6大类,其中新陈代谢功能占比最大,不同冻融阶段平均值占比75%以上。一级功能在完全冻结期和完全解冻期之间均具有显著性差异(P < 0.05)。具有显著性差异的二级功能中,几乎均在完全冻结期和完全解冻期之间存在显著差异(P < 0.05)。(4)土壤有机碳(SOC)、总氮(STN)、总磷(STP)是影响细菌群落结构组成和功能的主要环境因子,pH影响不显著。综上所述,不同冻融阶段(特别是完全冻结期)对细菌群落结构组成和功能具有显著影响,这种影响的变化与土壤性质SOC、STN、STP呈现显著正相关或负相关关系,研究结果为进一步研究气候变暖背景下黑龙江省季节冻土微生物的响应机制提供科学依据。  相似文献   

7.
板蓝根种子的吸水特性及发芽条件研究   总被引:1,自引:0,他引:1  
采用室内测定方法,对板蓝根种子的吸水特性及不同处理下种子的发芽率、发芽势和相对活力指数等进行比较研究。结果表明,板蓝根种子具有快速吸水的生物学特性,分为快速吸水期、缓慢吸水期和缓慢吐水期三个阶段,入水后2 h的吸水量达最大吸水量的73.29%,为快速吸水阶段;温度对板蓝根种子的萌发影响较大,最适发芽温度为30℃。光照、发芽床和种子预处理对板蓝根种子的萌发无明显影响。这说明板蓝根种子的萌发主要取决于水分和温度。  相似文献   

8.
甘肃省脆弱生态环境与贫困的耦合关系   总被引:5,自引:0,他引:5  
牛亚琼  王生林 《生态学报》2017,37(19):6431-6439
保持生态环境与经济建设的协调发展是新阶段国家扶贫开发的重要策略之一。以甘肃省为例,运用系统耦合协调度理论,构建双系统发展多指标综合评价体系,对研究区2000—2014年脆弱生态环境与贫困评价得分、两者耦合协调度及时空分异进行测度和分析。结果表明:从时序角度看,甘肃省脆弱生态环境和贫困耦合协调度整体呈上升状态,受政策调整等因素的影响呈现低水平耦合协调、耦合协调度增长、高水平耦合协调生态环境滞后3个不同阶段;从空间分异角度看,甘肃省脆弱生态环境和贫困耦合协调度由东南向西北递增,耦合协调度空间分布不均衡,脆弱生态环境与贫困共生共存,需充分重视和保护贫困地区生态环境。  相似文献   

9.
乔标  方创琳 《生态学报》2005,25(11):3003-3009
在分析城市化进程与生态环境状况之间交互胁迫、动态演进关系的基础上,借助于系统科学理论建立了城市化与生态环境协调发展的动态耦合模型。认为整个城市化过程就是城市化的各个层面与生态环境的综合协调、交互胁迫的耦合发展过程。在这一过程中,城市化与生态环境协调发展系统的演化周期将经历低级协调共生、协调发展、极限发展和螺旋式上升4个阶段,城市化与生态环境协调发展耦合过程的实质,就是系统各要素相互作用、相互制约,由低级协调共生向高级协调发展的螺旋式上升的过程。以河西走廊为例,对干旱区城市化与生态环境协调发展的动态耦合规律进行了实证分析,认为1985~2003年间,河西走廊城市化水平不断提高,生态环境状况曲折下降,生态环境对城市化的响应较为明显,但相对于城市化进程,生态环境的响应又有一定的滞后性。目前河西走廊处于城市化与生态环境的协调发展阶段,然而协调耦合度的增长很快,整个协调发展系统即将进入极限发展阶段,生态环境危机正在进入潜伏期。基于动态耦合模型所建立的协调耦合度,能够较好地反映城市化与生态环境的交互胁迫、动态耦合的演变情况。根据河西走廊耦合度的变化可知,在城市化发展的初期,往往是需要一定的生态破坏为代价的,然而随着城市化的发展,生态环境必将随城市化而好转。因此,正确认识城市化与生态环境交互胁迫的动态耦合规律,采取适当的城市化发展模式,对于促进河西走廊城市化与生态环境的协调发展具有重大意义。  相似文献   

10.
干旱区城市化与生态环境交互耦合的规律性及其验证   总被引:39,自引:1,他引:39  
乔标  方创琳  黄金川 《生态学报》2006,26(7):2183-2190
在分析干旱区城市化与生态环境交互耦合关系的基础上,系统阐述了城市化与生态环境之间的交互耦合函数、耦合轨迹、耦合类型和耦合阶段,并以河西走廊为例,对干旱区城市化与生态环境交互耦合的规律进行了验证.在干旱区城市化与生态环境之间,既有相互胁迫的过程,也有相互促进的环节,它们之间是一种在交互胁迫中相互促进的动态耦合关系;这种耦合关系在其演化周期内呈现出双指数函数的变化规律,其耦合演化轨迹是一条双指数曲线;在城市化与生态环境的交互耦合过程中,可能会出现低级协调型、生态主导型、同步协调型、城市化滞后型、逐步磨合型、城市化超前型、生态脆弱型、低级磨合型和不可持续型等九种基本耦合类型,并经历低水平协调、拮抗、磨合、好转和高水平协调等5个耦合阶段.河西走廊各城市城市化与生态环境交互耦合的演进过程符合双指数函数的变化规律,其耦合轨迹均呈现出双指数曲线的变化形式;嘉峪关市属于逐步磨合型,目前处于好转阶段;金昌市属于城市化超前型,处于磨合阶段;酒泉市属于生态主导型,处于拮抗阶段;张掖市属于同步协调型,处于拮抗阶段;武威市属于生态脆弱型,处于拮抗阶段;玉门市属于低级磨合型,处于好转阶段;敦煌市属于生态脆弱型,处于拮抗阶段;河西走廊属于生态脆弱型,处于拮抗阶段.  相似文献   

11.
War as a human disaster of major significance has led to an increase in the number of suicides committed by people suffering from mental disorders. Considering the results of similar research, we were particularly interested in the effect that war has on the incidence of suicide among of people with mental disorders. The research included 16,362 patients with mental disorders, treated at the Clinic for Psychiatry at the Clinical Hospital Split during the nine-year timeframe which were divided into pre-war (April 6th 1988- April 7rh 1991), wartime (April 6th 1991 -April 7rh 1994) and post-war (April 6th 1997 - April 7th 2000) periods. We studied the effects of how wartime events upon people with mental disorders in terms of their suicide rates, taking into account gender, age group, and the diagnosis under which they were treated. In our research, we found a statistically significant difference in suicide incidence between three observed periods (prewar April 6th 1988 April 7th 1991; wartime April 6th 1991 -April 7th 1994; and postwar April 6th 1997 -April 7th 2000) with the incidence being the highest during the wartime period (chi2 =9.98: p=0.007). Out of 16,362 patients treated at the clinic during the observed timeframe, a total of 78 people committed suicide. Twenty-two patients committed suicide during the first three year pre-war period; 36, during the three year wartime period; and 20, during the third three year post-war period. With this research we intended to offer a better understanding of the complexity of the suicide problem of mental patients as a phenomenon.  相似文献   

12.
Increasingly, environmental managers attempt to incorporate precautionary principles into decision making. In any quantitative analysis of impacts, precaution is closely related to the power of the analysis to detect an impact. Designs of sampling to detect impacts are, however, complex because of natural spatial and temporal variability and the intrinsic nature of the statistical interactions which define impacts. Here, pulse and press responses and impacts that affect time courses (temporal variance) were modelled to determine the influences of increasing temporal replication—sampling more times in each of several longer periods before and again after an impact.Increasing the number of control or reference locations and number of replicate sample units at each time and place of sampling investigated the influence of spatial replication on power. From numerous scenarios of impacts, with or without natural spatial and temporal interactions (i.e. not caused by an impact), general recommendations are possible. Detecting press impacts requires maximal numbers of control locations. Shorter-term pulse impacts are best detected when the number of periods sampled is maximized. Impacts causing changes in temporal variance are most likely to be detected by sampling with the greatest possible number of periods or times within periods.To allow precautionary decision making, the type of predicted impact should be specified with its magnitude and duration. Only then can sampling be designed to be powerful, thereby allowing precautionary concepts to be invoked.  相似文献   

13.
This article analyzes the problems of biosafety in terms of individual development patterns. Previously, the key role of epigenetic free radical processes in normal embryonic development of lower vertebrates in the formation of the competence and determination of embryonic primordia has been demonstrated, and a significant increase in the intensity of free radical process before every qualitative change in homeostatic mechanisms in developing organisms was found: in induction systems, before hatching of the embryo from the shells, and in preparation for metamorphosis. Thus, the activation of free radical processes in embryonic primordia corresponds to instability and characterizes the “critical periods of development” and increased sensitivity of the embryo to environmental impacts. Patented methods and a test system that allows detecting early biological effects of weak environmental impacts and predicting their environmental risk are presented. Possible mechanisms of significant biological effects of weak radiation and chemical impacts on the developing organism are discussed. The necessity of including embryonic objects in the protocol of testing the biosafety of technological developments is substantiated.  相似文献   

14.
The fish community and habitat structure in the littoral zone of lakes Pedra and Hortência, middle Rio Doce Valley, Brazil, were investigated in three sampling periods from August 1992 to May 1993. A total of 9106 fishes were collected, including 11 species in Lake Hortência and 12 species in Lake Pedra. Diversity was higher in Lake Hortência, although total fish abundance was the same for both lakes, with no significant temporal differences. The length distribution of the majority of fish species was similar between lakes. Geophagus brasiliensis was the dominant species (number/biomass) in all habitats of the two lakes in all three sampling periods. A striking difference in total fish abundance in relation to habitat types, which we attribute to physical variables, especially the abundance of macrophytes was observed. Negative impacts attributable to the local Eucalyptus sp. plantations were not detected in the fish community structure of Lake Hortência, which is probably due to the maintenance of the riparian vegetation contributing to similar physical environmental conditions in the littoral zone and high similarity in fish community structure between the two lakes. However, further studies on fish community structure and potential Eucalyptus impacts are suggested as necessary to improve conservation measures of the lakes and their fish faunas.  相似文献   

15.
There is an on-going debate on the environmental effects of genetically modified crops to which this paper aims to contribute. First, data on environmental impacts of genetically modified (GM) and conventional crops are collected from peer-reviewed journals, and secondly an analysis is conducted in order to examine which crop type is less harmful for the environment. Published data on environmental impacts are measured using an array of indicators, and their analysis requires their normalisation and aggregation. Taking advantage of composite indicators literature, this paper builds composite indicators to measure the impact of GM and conventional crops in three dimensions: (1) non-target key species richness, (2) pesticide use, and (3) aggregated environmental impact. The comparison between the three composite indicators for both crop types allows us to establish not only a ranking to elucidate which crop is more convenient for the environment but the probability that one crop type outperforms the other from an environmental perspective. Results show that GM crops tend to cause lower environmental impacts than conventional crops for the analysed indicators.  相似文献   

16.
Purpose

Many consumers are transitioning away from single-use plastic products and turning to reusable alternatives. Oftentimes, this change is being made with the assumption that these alternatives have fewer environmental impacts; however, reusable products are frequently made from more environmentally intensive materials and have use phase impacts. This study used LCA to examine the GWP, water consumption, and primary nonrenewable energy use associated with reusable alternatives for single-use plastic kitchenware products and determined environmental payback periods.

Methods

The environmental impacts for each reusable alternative are calculated on the functional units of 1 use, 1 year (5 uses/week), and 5 years (5 uses/week). Payback periods are calculated for each reusable alternative and defined as the number of times a consumer must reuse an alternative in order for the environmental impact per use to be equivalent to the environmental impact for the single-use product. The research explored the sensitivity of the results to different consumer washing and reuse behaviors, as well as local conditions such as overall transportation distances and the carbon intensity of different electricity grids. Product types studied included straws (4 reusable, 2 single-use), sandwich storage (2 reusable, 3 single-use), coffee cups (3 reusable, 2 single-use), and forks (1 single-use, 3 reusable).

Results and discussion

Environmental impacts associated with the reusable alternatives were highly dependent on the use phase due to dishwashing, making payback period sensitive to washing frequency and method, and for GWP, carbon intensity of the energy grid (used for water heating). For single-use products, the material/manufacturing phase was the largest contributor to overall impacts. It was found that nine of the twelve reusable alternatives were able to breakeven in all three environmental indicators. The coffee cup product type was the only product type to have one reusable alternative, the ceramic mug, and have the shortest payback period for all three impact categories. Both the bamboo straw and beeswax wrap were unable to breakeven in any scenario due to high use phase impacts from manual washing.

Conclusions

The research found that reusable alternatives can payback the environmental impacts of GWP, water consumption, and energy use associated with their more resource intensive materials, but it is dependent on number of uses, consumer behavior, and for GWP, carbon intensity of the energy grid. A key takeaway is that consumer behavior and use patterns influence the ultimate environmental impact of reusable kitchenware products.

Recommendations

Some recommendations for consumers looking to reduce the overall impact of kitchenware products include the following:

  1. 1)

    Not always assuming reusable is the best option.

  2. 2)

    Extending product lifetime.

  3. 3)

    Researching which reusable option has the lowest impact.

  4. 4)

    Following best practice washing behaviors.

  5. 5)

    Not washing products after every use.

  6. 6)

    Advocating for integration of renewables into the local energy grid.

  7. 7)

    Reducing consumption of these product types (reusable or single-use).

  相似文献   

17.
The environmental assessment of nanomanufacturing during the initial process design phase should lead to the development of competitive, safe, and environmentally responsible engineering and commercialization. Given the potential benefits and concerns regarding the use of single‐walled carbon nanotubes (SWNTs), three SWNT production processes have been investigated to assess their associated environmental impacts. These processes include arc ablation (arc), chemical vapor deposition (CVD), and high‐pressure carbon monoxide (HiPco). Without consideration of the currently unknown impacts of SWNT dispersion or other health impacts, life cycle assessment (LCA) methodology is used to analyze the environmental impact and provide a baseline for the environmental footprint of each manufacturing process. Although the technical attributes of the product resulting from each process may not be fully comparable, this study presents comparisons that show that the life cycle impacts are dominated by energy, specifically the electricity used in production. Under base case yield conditions, HiPco shows the lowest environmental impact, while the arc process has the lowest impact under best case yield conditions.  相似文献   

18.
Coral reef ecosystems are declining worldwide, yet regional differences in the trajectories, timing and extent of degradation highlight the need for in-depth regional case studies to understand the factors that contribute to either ecosystem sustainability or decline. We reconstructed social-ecological interactions in Hawaiian coral reef environments over 700 years using detailed datasets on ecological conditions, proximate anthropogenic stressor regimes and social change. Here we report previously undetected recovery periods in Hawaiian coral reefs, including a historical recovery in the MHI (~AD 1400-1820) and an ongoing recovery in the NWHI (~AD 1950-2009+). These recovery periods appear to be attributed to a complex set of changes in underlying social systems, which served to release reefs from direct anthropogenic stressor regimes. Recovery at the ecosystem level is associated with reductions in stressors over long time periods (decades+) and large spatial scales (>10(3) km(2)). Our results challenge conventional assumptions and reported findings that human impacts to ecosystems are cumulative and lead only to long-term trajectories of environmental decline. In contrast, recovery periods reveal that human societies have interacted sustainably with coral reef environments over long time periods, and that degraded ecosystems may still retain the adaptive capacity and resilience to recover from human impacts.  相似文献   

19.
Standard life cycle assessment (LCA) methodology has been used to determine and compare the environmental impacts of three different cooking fuels used in Ghana, namely, charcoal, biogas, and liquefied petroleum gas (LPG). A national policy on the use of cooking fuels would have to look at the environmental, social, and cost implications associated with the fuel types. This study looked at the environmental aspect of using these fuels. The results showed that global warming and human toxicity were the most significant overall environmental impacts associated with them, and charcoal and LPG, respectively, made the largest contribution to these impact categories. LPG, however, gave relatively higher impacts in three other categories of lesser significance—that is, eutrophication, freshwater aquatic ecotoxicity, and terrestrial ecotoxicity potentials. Direct comparison of the results showed that biogas had the lowest impact in five out of the seven categories investigated. Charcoal and LPG had only one lowest score each. From the global warming point of view, however, LPG had a slight overall advantage over the others, and it was also the most favorable at the cooking stage, in terms of its effect on humans.  相似文献   

20.
赵薇  孙一桢  张文宇  梁赛 《生态学报》2016,36(22):7208-7216
我国生活垃圾产量大但处理能力不足,产生多种环境危害,对其资源化利用能够缓解环境压力并回收资源。为探讨生活垃圾资源化利用策略,综合生命周期评价与生命周期成本分析方法,建立生态效率模型。以天津市为例,分析和比较焚烧发电、卫生填埋-填埋气发电、与堆肥+卫生填埋3种典型生活垃圾资源化利用情景的生态效率。结果表明,堆肥+卫生填埋情景具有潜在最优生态效率;全球变暖对总环境影响贡献最大,而投资成本对经济影响贡献最大。考虑天津市生活垃圾管理现状,建议鼓励发展生活垃圾干湿组分分离及厨余垃圾堆肥的资源化利用策略。  相似文献   

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