A retrospective analysis of contamination and periphyton PICT patterns for the antifoulant irgarol 1051, around a small marina on the Swedish west coast     

Blanck H  Eriksson KM  Grönvall F  Dahl B  Guijarro KM  Birgersson G  Kylin H 《Marine pollution bulletin》2009,58(2):230-237

Irgarol is a triazine photosystem II (PSII) inhibitor that has been used in Sweden as an antifouling ingredient since the 1990s. Early microcosm studies indicated that periphyton was sensitive to irgarol at concentrations regularly found in harbours and marinas. However, field studies of irgarol effects on the Swedish west coast in 1994, using the pollution-induced community tolerance (PICT) approach, failed to detect any effects of the toxicant in the field. A PICT study involves sampling of replicate communities in a gradient of contamination, and a comparison of their community tolerance levels, with an increase being an indication that sensitive species have been eliminated and replaced by more tolerant ones. Typically, short-term assays are used to quantify the community tolerance levels. Later PICT studies in the same area over a 10 year period demonstrate that irgarol tolerance levels have increased, although the contamination pattern has been stable. Our results support the hypothesis that that the PICT potential was low initially, due to a small differential sensitivity between the community members, and that a persistent selection pressure was required to favour and enrich irgarol-tolerant species or genotypes.  相似文献   

3种驼绒藜属植物种子萌发期耐盐性试验研究   总被引：13，自引：8，他引：5  

李得禄  王继和  李爱德  刘虎俊  安富博 《中国沙漠》2006,26(6):1009-1014

用0.3％,0.6％,0.9％,1.2％,1.5%、1.8%的NaCl溶液对3种驼绒藜属植物种子进行处理,观测它们的发芽率、发芽势、幼苗长度指标来研究驼绒藜属3种植物种子的耐盐性。试验研究表明:以1.2%或1.5%的NaCl溶液鉴定驼绒藜属植物耐盐性较为合理,3种驼绒藜属植物种子耐盐性存在明显差异。以NaCl溶液为培养液,随着浓度的增加,种子发芽率降低,种子发芽高峰的出现延迟,同时幼苗长度随盐分浓度的递增而呈减小趋势。综合分析发芽率、发芽势及幼苗长度,认为3种驼绒藜属植物种子的耐盐顺序为:华北驼绒藜最强、绵毛优若藜次之,驼绒藜最差。  相似文献   

Differential expression of PeSOS1, PeNhaD1 and PeNHX1 genes between the salt-tolerant Populus euphratica and salt-sensitive P. hopeiensis calli     

YuXia Wu 《寒旱区科学》2010,2(1):0043-0050

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Genetic diversity and metal tolerance of two marine species: a comparison between populations from contaminated and reference sites     

Ross K  Cooper N  Bidwell JR  Elder J 《Marine pollution bulletin》2002,44(7):671-679

Long-term contamination of the marine environment surrounding a lead smelter offered a unique opportunity to examine how pollutants might have acted to alter genetic characteristics of populations of organisms in the receiving system. This study used random amplified polymorphic DNA analysis to compare the genetic diversity of populations of the prawn, Leander intermedius, and the isopod, Platynympha longicaudata from the smelter discharge site with reference populations. The genetic diversity of the prawn population from the smelter discharge site (Port Pirie) was lower than that found in one reference population, and not significantly different from the other two reference populations. Genetic diversity of the Port Pirie population of isopods was found to be significantly lower than that of all reference populations. Prawns and isopods were also exposed to metal mixtures in the laboratory in a similar ratio to that found in seston near the smelter effluent discharge site. Both pre-exposed and reference populations of prawns tolerated elevated levels of metals and exhibited no significant difference in response. This contrasted with the isopods, with the pre-exposed isopod population showing greater tolerance to elevated metal levels compared with the reference population. These results highlight the need to include a number of reference populations for comparative purposes in genetic diversity studies, and the need to assess the influence of pollution on the genetic diversity of more than one species if genetic diversity analyses are to be used to gauge remediation success.  相似文献   

基于允许流失量和正负地形源汇理论的喀斯特关键带土壤侵蚀研究   总被引：6，自引：1，他引：5  

钱庆欢  王世杰  白晓永  周德全  田义超  李琴  吴路华  肖建勇  曾成  陈飞 《地理学报》2018,73(11):2135-2149

喀斯特地区下垫面的特殊复杂性使得地表发生显著坡面径流需要达到更大的降水累积阈值,碳酸盐岩岩石成土速率的缓慢和空间异质性导致喀斯特地区的土壤存量被严重高估和均一化等,因此,传统经典的土壤侵蚀模型在喀斯特地区难以适用。本文依据喀斯特关键带岩性的差异,确定其有效降水侵蚀阈值,并对降雨侵蚀力进行重新测算;根据碳酸盐岩化学成分的差异,计算其成土速率并作为土壤允许流失量;通过地貌—水文分析法提取喀斯特洼地空间分布信息,对喀斯特关键带土壤侵蚀算法进行多次改进和创新。结果显示：① 传统算法忽视了喀斯特关键带下垫面的特殊性,致使其平均降雨侵蚀力被高估47.35%,且喀斯特区域的平均降雨侵蚀力仅相当于非喀斯特区域的59.91%;② 传统算法可能将一些无土或少土可流区计算为土壤的高侵蚀量区,而连续性碳酸盐岩、碳酸盐岩夹碎屑岩、碳酸盐岩与碎屑岩互层的土壤允许流失量仅分别为0.21 t ha^-1 yr^-1、1.2 t ha^-1 yr^-1、2.89 t ha^-1 yr^-1;③ 传统算法通常将有坡度和耕作的洼地视为土壤侵蚀的高发区,但其实际应是地表侵蚀的沉积区,喀斯特洼地在空间上的连续性与碳酸盐岩的分布区基本重合;④ 传统算法高估土壤侵蚀面积27.79%,土壤侵蚀量47.72%。总之,传统经典模型会大大高估喀斯特地区的土壤侵蚀量,因此,应该建立一种精确适用的模型。另外,由于喀斯特地区的成土速率慢而土层薄、总量少,土壤允许流失量远低于非喀斯特区域侵蚀标准,应制定适用于喀斯特地区的土壤侵蚀分类分级标准和风险评价方法。  相似文献   

多属性直觉模糊容差粗糙集模型     

徐伟华  苑克花  李文涛 《南京气象学院学报》2020,12(3):284-288

在直觉模糊信息系统的背景下提出了基于容差关系的直觉模糊粗糙集模型,从乐观悲观两个角度出发对目标集进行刻画,是对目标集的一种新的逼近方法,同时,可以发现乐观与悲观上下近似的关系.通过求解近似精度可以发现乐观直觉模糊粗糙集模型的近似精度更高.最后给出实证分析,进一步验证结论的有效性.  相似文献   

房产地籍中房屋面积测算方法及精度分析   总被引：1，自引：0，他引：1  

赵宝锋  董春来 《北京测绘》2006,(3):41-43

随着城市房地产价格的不断增涨,房地产面积测算的精度要求越来越高。本文通过对坐标解析法和实地量距法测算面积的精度分析和对比论证,得出比较合理的房屋面积测算的限差公式。  相似文献   

From regime protection to urban resilience? Assessing continuity and change in transnational security governance rationales in Guatemala     

《Geoforum》2017

This article analyzes changing forms of transnational security governance and security expertise in Guatemala. It is argued that the dynamics of transnational security governance in Guatemala are directly related to the local appropriation of knowledge promoted by external security experts. As an expertise-based form of “intervention by invitation,” local political and economic elites engage in securitization strategies in order to invite external experts to intervene. In turn, through their intervention these experts provide resources that are “captured” and exploited by local actors to pursue their own interests. As a consequence, transnational security governance fails as it deviates from the original plans and programs experts try to implement. The analysis of these processes sheds light on how and why failure in the context of transnational security governance is productive. Failure, we argue, triggers a self-reinforcing interventionary feedback loop that aims at “fixing” the shortcomings of previous interventions by mobilizing new forms of external security expertise. In tracing the dynamics of this interventionary feedback loop over time, this article contributes to understanding of the role of experts and policy failure in the (re)making of transnational security governance.  相似文献   

基于微博数据的中国人群气温感知时空分异特征及影响因素分析     

翁慧娴  马廷 《地球信息科学学报》2022,24(10):2058-2070

极端气温事件发生频率的增加对人群的健康带来了很大的影响,深入理解人群对气温变化的感知特征有助于提高应对极端气温事件的预警、适应和管理水平。针对传统调查数据在样本量和覆盖度等方面的不足,本文使用基于微博的社交媒体数据来研究人群对气温感知的定量特征。研究通过建立气温关注度、敏感性和耐受性等指标,调查了中国2017年31个城市的人群对气温感知的空间格局变化与局部变异性,分析了不同季节和不同群体对气温感知的差异性与影响因素。分析结果表明：人群对气温的感知表现出显著的纬度梯度规律性,纬度每下降1°,人群平均的热耐受性增强0.42oC,冷耐受性降低0.31oC,冷敏感性增强0.51;人群对气温的感知在不同季节、不同群体之间也表现出显著的差异性,反季的异常气温更易引起人群对于气温变化的关注,青少年与女性群体对冷更为敏感;气温感知特征的区域差异性与气候分区紧密相关,温带地区的人群比热带显示出更强的热耐受性,而热带地区的人群具有更显著的气温敏感性。本文研究结果可以为理解大尺度上人群对气温变化感知的基本特征和分异规律提供新的规律发现与证据支持。  相似文献   

单环刺螠对硫化物暴露的呼吸代谢适应     

张志峰  王思锋  霍继革  邵明瑜  康庆浩 《中国海洋大学学报(自然科学版)》2006,36(4):639-644

研究硫化物暴露后单环刺组织细胞色素氧化酶(CCO)、琥珀酸脱氢酶(SDH)、延胡索酸还原酶(FRD)等呼吸代谢酶活性的变化,初步探讨了单环刺对硫化物的呼吸代谢适应。将虫体暴露于50,150μmol/L 2个硫化物组和不含硫化物的对照组水体中,分别于暴露后0,2,12,24,48 h和解除暴露后48 h取体壁、呼吸肠等组织进行酶活性分析。结果显示:暴露2 h时,硫化物组CCO活性上升。24 h时,150μmol/L组CCO活性显著低于对照组,到48 h时接近于0,而SDH活性显著低于对照组,FRD活性极显著高于对照组。解除暴露后48 h,虫体的呼吸代谢酶活性与对照组无显著差异。可见,硫化物暴露后,短期内虫体呼吸代谢提高,可能进行硫化物氧化解毒。而随着暴露时间的延长,虫体的呼吸代谢减弱,FRD活性极显著增高,推测体内可能存在将延胡索酸还原成琥珀酸的无氧代谢方式。解除硫化物暴露后,虫体具有较强的自我恢复能力。  相似文献