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.
第1期专家论坛高职教育可持续发展若干关系论陈剑旄(1)生物马尾松幼胚培养愈伤组织诱导的初步研究杨艳,李志辉,丁贵杰,等(6)湖南蝶类研究朱巽,马华元(10)环境科学郑州市农村饮用水安全评价刘新宇,齐登红,宁立波(13)济南市生态环境与资源可持续利用研究李传生,马传明,刘宏伟,等(16)基于水生植物对污染物的清除及其应用研究李君俐(20)理工科学粉喷桩体的力学性质试验研究罗思京(23)某大型储罐复合地基沉降计算分析刘建泰,马义华,宁仟俊(26)电磁线包磁场对慢波系统电子光学特性的影响李步青(30)用剪力图面积法绘制弯矩图高建亮,赵林艳,赵林峰(3…  相似文献   

2.
为探讨氮硫沉降对华北暖温带森林土壤呼吸的影响规律以及与温度、湿度的关系,在落叶松人工林中开展了野外模拟氮硫沉降试验.结果表明:在生长季,各氮硫水平样地月平均土壤呼吸有明显的季节变化特征,模拟氮硫复合沉降对华北落叶松林土壤呼吸产生显著影响(P0.05).生长季内,氮沉降促进土壤呼吸速率,其中高氮与CK产生显著差异(P0.05).土壤呼吸速率与硫沉降水平呈正相关关系(P0.05).氮硫复合沉降促进了土壤呼吸速率,高氮高硫与CK土壤呼吸速率产生显著差异(P0.05),而中氮中硫水平抑制土壤呼吸速率,但未达到显著水平(P0.05).中氮和中硫对土壤呼吸速率的影响大于二者的共同作用,产生拮抗作用,而高氮高硫产生协同作用.各处理土壤呼吸速率与5 cm土壤温度呈极显著正相关关系.土壤温湿度双因子模型预测土壤呼吸的准确性和稳定性高于单因子模型.模拟氮硫沉降增加了土壤Q_(10)值,而高氮高硫降低了土壤Q_(10)值.试验结果揭示了太岳山华北落叶松林土壤呼吸特征对氮硫复合沉降的响应,即除中氮中硫外,复合沉降不同程度地促进了土壤呼吸速率,其复杂的响应机制仍有待进一步研究.  相似文献   

3.
通过对南昌郊区一片樟树林上空氨浓度的实地监测,用微气象学浓度梯度法计算了氨的干沉降速率,在稳定和中性大气情况下,氨的干沉降速率范围为一0.96—2.09cm.s~(-1),平均值为 0.62 cm.s~(-1).  相似文献   

4.
福建省兴化湾大气沉降中重金属的测定   总被引:3,自引:1,他引:3  
于2004年7月至2005年6月期间分季度对福建省兴化湾大气沉降颗粒物进行采集和分析,并对10种元素的沉降通量(mg·m-2·a-1)进行了计算,其中,Cd:0.08±0.01;Cr:11.63±7.82;Cu:2.72±0.99;Ni:7.81±1.18;Pb:3.83±1.96;Zn:14.39±6.58.结果表明, 兴化湾大气沉降中重金属的污染状况相对较好.铅同位素研究表明,人们的生产活动可能是大气沉降中Pb污染的主要来源.通过对元素富集因子的计算说明大气沉降中Cd,Pb,Zn,Cr和Ni主要为人为来源.  相似文献   

5.
氮、硫沉降对尾巨桉和杉木幼苗光合特性的影响   总被引:1,自引:0,他引:1  
采用二因素三水平法设计模拟氮(N)、硫(S)沉降的盆栽试验,以Na2SO4为硫源、46%CO(NH2)2为氮源,其中氮沉降梯度为N1(0 kg hm-2 a-1)、N2(50 kg hm-2 a-1)、N3(100 kg hm-2 a-1),硫沉降梯度为S1(0 kg hm-2 a-1)、S2(15kg hm-2 a-1)、S3(30 kg hm-2 a-1).模拟试验6个月后,测定尾巨桉(Eucalyptus urophylla×Eucalyptus grandis)和杉木(Cunninghamia lanceolata)幼苗的SPAD值、可溶性蛋白含量、净光合速率(Pn)和叶绿素荧光参数,分析探讨氮、硫沉降处理下两树种幼苗光合特性的响应机制.结果表明:与空白对照组相比,单一中氮沉降显著促进两树种幼苗Pn的上升(P<0.05),且单一高氮沉降显著促进杉木幼苗可溶性蛋白含量的上升(P<0.05),表明单一氮处理在一定程度上提高了两树种幼苗的光合能力.尾巨桉幼苗各光合指标受单一硫沉降胁迫的影响较杉木幼苗更为显著,前者的SPAD值和可溶性蛋白含量在中硫处理下均显著下降(P<0.05),Pn反之;而后者仅SPAD值在中、高硫处理下显著上升(P<0.05).氮、硫复合沉降下,尾巨桉幼苗各项指标未见明显变化(P>0.05);杉木幼苗仅中氮高硫组的SPAD值和高氮高硫组的可溶性蛋白含量显著上升(P<0.05).综上,与单一氮、硫沉降相比,氮、硫复合沉降的交互效应并未显著增强两树种幼苗的光合特性,但两树种幼苗间对模拟氮、硫沉降的响应和耐受机制存在差异.  相似文献   

6.
广东韶关地区大气氮干湿沉降特征研究   总被引:4,自引:0,他引:4  
2012 年4 月-2013 年9 月利用自动分离干湿沉降的采样器对广东省韶关市降雨和干沉降进行采集,分析样品降雨量、降尘量及氮营养盐干湿沉降浓度,计算各指标干湿沉降通量,利用沉降通量分析其影响因素及季节性变化趋势,为该地区大气氮沉降的通量预测及其环境管理提供支持,并为其生态环境中污染物的控制与减排提供科学依据.结果表明,观测期间总氮干沉降通量、湿沉降通量和总沉降通量平均值分别为47.73、295.7 和310.5 kg·km^-2·month^-1.氨态氮、硝酸盐氮与有机氮干沉降通量平均值分别为17.39、12.98 和17.37 kg·km^-2·month^-1,其湿沉降通量平均值分别为132.4、117.0 和46.23kg·km^-2·month^-1.总氮湿沉降通量占总氮总沉降通量平均比例为83.19%,说明总氮沉降通量以湿沉降为主.影响因素方面,总氮干沉降通量与降尘量无相关性;湿沉降受降雨量影响较大,所以受雨季影响,韶关地区4-6 月总氮湿沉降负荷较大.成分组成上,干沉降中氨态氮平均占总氮比例35.48%,硝酸盐氮平均占27.96%,有机氮平均占36.55%,因此该地区氮营养盐干沉降中以氨态氮和有机氮为主;氮营养盐湿沉降以氨态氮和硝酸盐氮为主,氨态氮平均占总氮比例46.87%,硝酸盐氮平均占40.64%,有机氮平均比例为12.49%,说明该地区湿沉降同时受到农业活动和工业活动的影响.季节变化上,氮营养盐干沉降通量由大到小依次为冬季、春季、秋季、夏季,湿沉降通量春季较高,夏秋两季较低.  相似文献   

7.
于2008年在上海市浦东农业区设置采样点按月收集降水样品,测定降水NO3--N和NH4+-N浓度,分析氮浓度的变化规律及其影响因素,并计算氮沉降通量。结果表明,浦东农业区降水氮浓度和年沉降通量均较高,ρ(NO 3--N)平均值为0.44 mg.L-1,年沉降通量为5.19 kg.hm-2.a-1;ρ(NH 4+-N)平均值为1.36 mg.L-1,年沉降通量为15.91 kg.hm-2.a-1;TN年沉降通量为21.10 kg.hm-2.a-1,其中NH4+-N占75.4%。降水NO3--N和NH 4+-N浓度在主要生长季(4—10月)低于非主要生长季(11月至次年3月);而NH 4+-N沉降量在主要生长季高于非主要生长季,NO3--N沉降量在主要生长季和非主要生长季差异较小,这主要是人为活动、降水日数与降水量以及风向等因素的综合作用所致。降水氮输入对研究区初级生产力的提高具有积极意义,但降雨氮浓度已超过水体富营养化阈值,可能加剧农业区内水体富营养化。  相似文献   

8.
联苯胺对大型溞(Daphnia magna)的急性和慢性毒性试验   总被引:4,自引:1,他引:4  
研究了联苯胺对大型溞(Daphniamagna)的急性毒性和慢性毒性.急性毒性试验结果表明,联苯胺对大型溞的ρLC50, 24h、ρLC50, 48h值分别为 1. 73mgL-1和 0. 89mgL-1. 21d生活周期试验结果表明,大型溞的生殖是对该化合物最为敏感的慢性毒性指标.联苯胺对大型溞生殖的无可见效应浓度(NOEC/Reproduction)为 0. 004mgL-1,最低可见效应浓度(LO EC/Reproduction)为 0. 012mgL-1.并据此计算出该毒物的最大允许浓度(MATC)为 0. 008 9mgL-1. 表 3参 19  相似文献   

9.
粘土矿复合聚合氯化铝凝聚给水中的藻类   总被引:7,自引:0,他引:7  
赵春禄  于彦君 《环境化学》2004,23(3):301-305
采用粘土矿复合聚合氯化铝 (PAC)对凝聚给水中的藻类进行了研究 .结果表明 ,粘土矿的加入不仅可显著增加絮体的密实度 ,加快其沉降速度 ,使沉淀后的活藻絮体在微扰动下不再漂浮上升 ,从而可有效阻止堵塞滤池 ,而且使沉淀后的底泥体积减少了 31 % ,沉降后出水中叶绿素a的浓度降到 1 3μg·l- 1 ,铝的含量低于 0 2mg·l- 1 .  相似文献   

10.
采用高锰酸钾预氧化复合高岭士与聚合氯化铝(PAC)混凝,对去除水中颤藻进行了研究.通过正交试验得出了在试验水质条件下,颤藻去除最佳条件为:高锰酸钾投加量为0.5mg·l~(-1),预氧化时间为15min,PAc投加量为2.5mg·l~(-1),粒径为160目的高岭土投加量为50mg·l~(-1).在此条件下,高锰酸钾可氧化颤藻失活但并没有破坏藻细胞壁,防止了藻毒素的释放.预氧化产生的水合二氧化锰作为凝结核促进了絮体的形成,并使之更加密实、易沉降,且沉降后藻絮体不再上浮,提高了处理后的水质.  相似文献   

11.
粉喷桩是处理软弱地基的一种重要方法.通过水泥土的室内配合比试验,研究了粉喷桩体的抗拉、抗压和抗剪强度性质及其影响因素,可为粉喷桩施工和设计提供理论指导.图1,表3,参5.  相似文献   

12.
Balanus subalbidus (Henry) has the most oligohaline distribution of three congeneric barnacles in Chesapeake Bay and tolerates prolonged exposure to fresh water. We studied larval settlement (i.e., permanent attachment and metamorphosis) of B. subaldius in the laboratory, over a 3 yr period, May 1989 to March 1992, under the following conditions: (1) across an array of salinities at 25°C in the presence and absence of settlement factor consisting of adult B. subalbidus extract; (2) in the presence of conspecific or congeneric settlement factors; and (3) cyprids which were, and were not, induced to delay metamorphosis were compared in their capacities to settle in a range of salinities. Discrepancies between salinity profiles of larval settlement in the laboratory and adult oligohaline distribution in the estuary were striking, and there was a significant interaction between salinity and settlement factor. Averaging results of four different batches of larvae, although peak settlement (87±9%) of B. subalbidus occurred at 2 ppt salinity in the presence of adult cue, substantial settlement also occurred at higher salinities: >70% at 5, 10 and 15 ppt; and 47% at 20 and 25 ppt. In addition, settlement in the absence of settlement factor was relatively high (>50%) and peaked at mid-salinity ranges (e.g. 56±10% at 15 ppt). Variation observed in settlement among larval batches reflected detailed differences in settlement between adjacent test salinities. No difference in settlement occurred between replicate aliquots of cyprids within a batch. Cyprids of B. subalbidus settled most abundantly in the presence of settlement factor extracted from conspecifics, followed in decreasing order by settlement factor extracted from B. improvisus and B. eburneus. Delay of metamorphosis produced by keeping B. subalbidus cyprids for 8 d at 5°C resulted in a decreased level of settlement, but settlement frequency patterns of delayed and non-delayed cyprids were indistinguishable relative to salinity. These results indicate that the oligohaline distribution of adult B. subalbidus is probably not determined by larval behavior at settlement. We suggest that pre-settlement behavior, resulting in larval retention in low saline waters, could be an important factor in determining distribution of this species.  相似文献   

13.
This paper describes a flume tank in which the various physical and behavioural conditions encountered by swarming macroplankton can be manipulated, and a mathematical stereophotographic technique, for use in the calculation of the three-dimensional co-ordinates of individual organisms within the swarms. The mathematical model incorporates the Direct-Linear Transformation equation which describes the position of the object and its image in relation to the camera-perspective centre of the photographic system. Combining this equation with a modified light-ray tracement technique to solve for the passage of light through a three-media environment, the actual three-dimensional co-ordinates of the individual organisms and subsequently their inter-individual distances, bearings and angles of elevation may be derived. The distances between adjacent animals can be measured to an accuracy of 0.24 mm (SD=0.21) using this photogrammetric technique. The design of the flume tank allows for the manipulation of water current speed and flow patterns, substrate, and light intensity. Six species of mysid and one species of euphausiid have been induced to swarm in the flume tank. The conditions required to induce swarming and schooling in the laboratory are described. The inter-individual distances, bearings and angles of elevation have been calculated for Paramesopodopsis rufa, Anisomysis mixta australis, Australerythrops paradicei (Crustacea: Mysidacea) and Nyctiphanes australis (Crustacea: Euphausiacea) using the stereophotographic technique.  相似文献   

14.
岷江上游山区聚落生态位及其模型   总被引:6,自引:0,他引:6  
以生态位基本理论为基础,提出了山区聚落生态位的概念,即山区聚落生态位反映聚落在山地垂直方向上所处的空间位置及人类生活所能利用的资源空间。构建了山区聚落生态位宽度计测模型,以岷江上游杂谷脑河段上下孟沟为例,计算了区内12个聚落的生态位宽度。结果表明,在该聚落群的聚落生态位计算中,自然因素占主导地位,经济因素次之,社会因素影响最小;海拔高度为1900—2600m时,山区聚落生态位宽度为0.03—0.11,海拔高度为〉2600-3100m时,山区聚落生态位宽度大多分布在0.12~0.13之间,聚落生态位随海拔升高呈增大趋势。山区聚落生态位研究可为揭示山区人地关系以及聚落空间规划提供新的评估方法。  相似文献   

15.
运用位移监控信息、土体平衡原理、护壁桩支撑设计原理指导深基坑支护适应基坑深度变大的难题,具有施工方便、经济、安全的、工期短等特点,为在闹市区深基坑支护施工提供了经验.图1,表1,参7.  相似文献   

16.
Over the past several decades, we have argued that cultural evolution can facilitate the evolution of large-scale cooperation because it often leads to more rapid adaptation than genetic evolution, and, when multiple stable equilibria exist, rapid adaptation leads to variation among groups. Recently, Lehmann, Feldman, and colleagues have published several papers questioning this argument. They analyze models showing that cultural evolution can actually reduce the range of conditions under which cooperation can evolve and interpret these models as indicating that we were wrong to conclude that culture facilitated the evolution of human cooperation. In the main, their models assume that rates of cultural adaption are not strong enough compared to migration to maintain persistent variation among groups when payoffs create multiple stable equilibria. We show that Lehmann et al. reach different conclusions because they have made different assumptions. We argue that the assumptions that underlie our models are more consistent with the empirical data on large-scale cultural variation in humans than those of Lehmann et al., and thus, our models provide a more plausible account of the cultural evolution of human cooperation in large groups.  相似文献   

17.
Urban ecological risk characterization is the final step in risk assessment and an important foundation upon which risk managers build risk aversion, risk control, and emergency handling strategies. In this study, we reviewed present risk characterization methods and proposed a multi-level characterization method for the assessment of urban ecological risks. The new characterization method consists of four elements: urban ecological risk sources, risk source probabilities, assessment endpoint indicators, and assessment endpoint indicator probabilities. Using this method, results of risk assessments can be organized into different levels of detail to meet different risk management goals.  相似文献   

18.
基于水文学方法的珠江流域生态流量研究   总被引:1,自引:0,他引:1  
张强  崔瑛  陈永勤 《生态环境》2010,19(8):1828-1837
珠江流域水资源丰富,但由于水体污染等原因,水质性缺水问题较为突出,区域水环境、水生态以及水安全等成为急需解决的重要科学问题。开展生态流量研究对于评价地表水文过程演变对区域水环境与水生态的影响具有重要理论意义,并为区域水资源优化配置和可持续开发利用提供科学依据。基于此,运用各种"水文学"方法(包括最小月平均流量法、改进的7Q10法、NGPRP法、逐月最小生态径流计算法和逐月频率计算法)对珠江流域11个主要水文控制站点的实测月径流量做了全面而系统的研究,分析珠江流域生态径流过程,并通过与Tennant法对比分析,选择逐月最小生态径流计算法和逐月频率计算法分别计算了各水文控制站的最小生态径流量和适宜生态径流量,除个别站点外,其评价结果分别处于Tennant法"中"和"最佳"的等级。对于逐月频率计算法中保证率的选取方法,研究表明各月径流系列均取50%最适合珠江流域。研究同时为仅利用水文资料中的多年逐月径流数据来确定生态需水提供了一种新的研究思路。  相似文献   

19.
郭蔚华  马金龙  吴玉龙 《生态环境》2010,19(11):2733-2736
藻红外测试法是利用毒物引起敏感藻红外辐射变化可被测试的一种急性毒性分析方法。敏感藻是指急性毒性藻红外测试中对毒害物质响应温差大、时间快、药品多、剂量低的特殊藻种。在藻红外测试多元有机毒物时,由于毒物毒性的联合作用将直接影响敏感藻的敏感性,因此敏感藻对多元有机毒物浓度的敏感性在联合毒性测试分析时需要首先认知。实验通过测试敏感藻对5种有机毒物不同组合的响应,为联合毒性测试分析时敏感藻敏感性不变提供了多元有机毒物浓度设计依据。实验用羊角月牙藻(Selenastrum capricornutum)作敏感藻,苯(C6H6)、甲苯(C7H8)、二甲苯(C8H10)、氯苯(C6H5Cl)、三氯甲烷(CHCl3)为实验药品。结果表明:有机毒物混合后确实产生了温差的变化,的确有联合作用存在。5种有机毒物的一元、二元、三元、四元、五元组合,其藻液中多元有机毒物质量浓度为100~500 mg.L-1时,敏感藻均有温度响应且可被测试出,表明该质量浓度范围内敏感藻具有敏感性,可作有机毒物联合毒性分析的参照质量浓度,但100~200 mg.L-1为宜。  相似文献   

20.
Proposals for marine conservation measures have proliferated in the last 2 decades due to increased reports of fishery declines and interest in conservation. Fishers and fisheries managers have often disagreed strongly when discussing controls on fisheries. In such situations, ecosystem‐based models and fisheries‐stock assessment models can help resolve disagreements by highlighting the trade‐offs that would be made under alternative management scenarios. We extended the analytical framework for modeling such trade‐offs by including additional stakeholders whose livelihoods and the value they place on conservation depend on the condition of the marine ecosystem. To do so, we used Bayesian decision‐network models (BDNs) in a case study of an Indonesian coral reef fishery. Our model included interests of the fishers and fishery managers; individuals in the tourism industry; conservation interests of the state, nongovernmental organizations, and the local public; and uncertainties in ecosystem status, projections of fisheries revenues, tourism growth, and levels of interest in conservation. We calculated the total utility (i.e., value) of a range of restoration scenarios. Restricting net fisheries and live‐fish fisheries appeared to be the best compromise solutions under several combinations of settings of modeled variables. Results of our case study highlight the implications of alternate formulations for coral reef stakeholder utility functions and discount rates for the calculation of the net benefits of alternative fisheries management options. This case study may also serve as a useful example for other decision analyses with multiple stakeholders. Modelo de Red de Decisión Bayesiana de Múltiples Actores Interesados en la Restauración de Ecosistemas de Arrecife en el Triángulo de Coral  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