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581.
以斑马鱼为受试生物,通过水质毒性生物监测仪记录行为轨迹,研究了亚致死浓度的马拉硫磷急性暴露下斑马鱼游动行为和群体分布等多项行为参数的变化。结果表明:斑马鱼对环境变化响应快速,游动速度短时间内急剧增大,之后下降再调整稳定至一定范围,变化趋势符合环境压力模型。游泳高度不断增大,暴露1 h后斑马鱼几乎全部集中到水箱上部,与暴露前水平差异显著。通讯行为参数平均距离和分散度在暴露后短时间内减小之后恢复到暴露前水平。通过解析斑马鱼的行为变化可以实现水体有机磷农药突发污染的早期预警。 相似文献
582.
城市格局时空演变以土地利用变化为承载,为城市用地调控、空间发展政策的制定提供依据。以武汉市主城为实证区,采用1989、1999、2008和2015年4期Landsat遥感影像为数据源,综合空间信息技术、用地扩张量化分析方法研究城市土地利用转换关系,测度建设用地扩张强度、弹性与方向,揭示城市格局时空演变过程。结果表明:1989~2015年间,武汉市主城区土地利用变化以建设用地扩张、未利用地和耕地减少为主,经济增长与建设用地扩张关联度高;主城区建设用地在1999年之后扩张速度明显加快,总体扩张强度逐步加强。建设用地扩张呈现时空不平稳状态,扩张主要集中在以汉阳、青山为代表的城郊过渡带区域,以及硚口、武昌等老城区的更新改造区域,1989~2008年间扩张方向以偏西向为主,2008~2015年间扩张方向以东南向为主,反映城市区域发展阶段的差异和空间开发政策变动的影响。 相似文献
583.
Discharge and Nutrient Transport between Lakes in a Hydrologically Complex Area of Voyageurs National Park,Minnesota, 2010‐2012 下载免费PDF全文
Victoria G. Christensen Eric S. Wakeman Ryan P. Maki 《Journal of the American Water Resources Association》2016,52(3):578-591
An acoustic Doppler velocity meter (ADVM) was deployed in the narrows between Namakan and Kabetogama Lakes in Voyageurs National Park, Minnesota, from November 3, 2010, through October 3, 2012. The ADVM can account for wind, seiche, and changing flow direction in hydrologically complex areas. The objectives were to (1) estimate discharge and document the direction of water flow, (2) assess whether specific conductance can be used to determine flow direction, and (3) document nutrient and chlorophyll a concentrations at the narrows. The discharge direction through the narrows was seasonal. Water generally flowed out of Kabetogama Lake and into Namakan Lake throughout the ice‐covered season. During spring, water flow was generally from Namakan Lake to Kabetogama Lake. During the summer and fall, the water flowed in both directions, affected in part by wind. Water flowed into Namakan Lake 70% of water year 2011 and 56% of water year 2012. Nutrient and chlorophyll a concentrations were highest during the summer months when water‐flow direction was unpredictable. The use of an ADVM was effective for assessing flow direction and provided flow direction under ice. The results indicated the eutrophic Kabetogama Lake may have a negative effect on the more pristine Namakan Lake. The results also provide data on the effects of the current water‐level management plan and may help determine if adjustments are necessary to help protect the aquatic ecosystem of Voyageurs National Park. 相似文献
584.
应对气候变化的科学基础是摸清区域碳排放基本状况,对碳排放现状的梳理是探索环境改善路径的依据。探索低碳发展路径的核心在于减排政策选择,同时也是实现可持续发展的条件保障。京津冀协同发展背景下区域环境保护及大气污染治理成为研究热点,河北省资源环境容量与经济增长之间的矛盾日益凸显,生态文明、可持续发展的要求促使探明环境现状,研究节能减排低碳发展的创新机制。摸清河北省碳排放基本现状,探明能源需求和碳排放的演变规律,对河北省探索低碳发展路径具有实践意义。本文基于河北省全域的数据资料和实地调查,核算了河北省下辖11个地级市能源活动引起的碳排放,分析了2005-2013年碳排放的时空演化规律,以情景分析方法为基础,预测了河北省到2030年的碳排放状况。认为:第一,能源活动的碳排放量从研究时间尺度上来看,始终保持增长的趋势,且2009年以后增长更为显著;从空间尺度上来看,唐山市的排放始终是全省最高。第二,基于情景分析对河北省能源活动的碳排放可能状况进行预测。基准情景是排放量最高的情景;低碳情景下2025年前后碳排放量基本稳定;强化低碳情景下设定2030年回到2005年的排放水平上,人均碳排放量始终保持下降,2030年将与全国2012年的人均排放平均水平相当。 相似文献
585.
Abstract A simple technique was demonstrated for determining the potential for synthetic organics to stress microbial populations. Oxidized Crowley and Cecil soil materials were amended with varying concentrations of 2,4‐D and methyl parathion, flooded, and then analyzed for changes in pH, redox potential, and levels of soluble plus exchangeable Fe, Mn, and Zn, all of which may be directly or indirectly influenced by the activity of soil microorganisms. At the concentrations tested (up to 75 ppm), there was little effect of 2,4‐D, but methyl parathion apparently did affect microbial activity contributing to changes in the measured soil properties upon flooding. This approach may be a useful technique for screening various compounds for their potential to stress microbial activity that, for many researchers, would be easier than direct observations of microbial parameters such as population numbers and classifications, and enzyme levels. 相似文献
586.
Quantification of land use/land cover changes in Pearl River Delta and its impact on regional climate in summer using numerical modeling 总被引:2,自引:0,他引:2
Wenshi Lin Lu Zhang Dongsheng Du Limin Yang Hui Lin Yuanzhi Zhang Jiangnan Li 《Regional Environmental Change》2009,9(2):75-82
This study quantified land use/land cover (LULC) changes in Pearl River Delta (PRD) of South China and its impact on regional
climate over the last two decades. The LULC change analyses were accomplished by applying a change detection method to a set
of Landsat imagery and ancillary data acquired from 1970s to 2000. The results indicate that the urban expansion is the prevailing
LULC change in the PRD. Impact of LULC change on regional climate was simulated by using a mesoscale climate model. Two different
land cover datasets circa 1990 and 2000 were input to the model to investigate the impact of urbanization on regional weather
and climate condition in summer 2005. The simulation results show that rapid urban expansion can substantially alter regional
climate conditions in the PRD region including monthly mean temperature, precipitation, moisture, and surface heat fluxes. 相似文献
587.
Biodiversity conservation and management of natural resources are the best options to restore and increase productivity of
degrading pastureland in dry areas. Hence, arthropod abundance, organic matter, respiration, and dehydrogenase activity were
measured in canopy zone soil of Prosopis cineraria (PC), Acacia nilotica (AN), Zizyphus nummularia (ZN), Capparis decidua (CD), and Acacia senegal (AS) associated with grasses with a view to establish interrelation for productivity enhancement of pastureland. Pure grass
bock outside tree canopy was control plot. Acari, Myriapoda, Coleoptera, Isoptera, Collembola, and other soil arthropods were
the major soil faunal groups. Integration of tree in pastureland enhanced population of soil arthropod by 9–65-fold in May
2001 and 8–13-fold in August/September as compared with control. The trends of changes in soil organic matter (SOM), soil
respiration (SR), and dehydrogenase activity (DHA) were similar to the changes in soil arthropod population, indicating the
role of soil fauna in facilitating biochemical processes and soil fertility. Two, eight, and nine times greater SOM, SR, and
DHA, respectively, in silvipastoral system than the values in control suggest the beneficial effects of trees on improvement
in biochemical processes and thus biodiversity in pastureland, as supported by negative values of relative tree effects (RTE).
Microbial activities were highest in the ZN system, which had highest abundance of soil arthropods. In the other systems,
CD and AS systems showed greater soil arthropod abundance and biological activities than with the PC and AN systems. Therefore,
Z. nummularia-, C. decidua-, and A. senegal-based silvipastoral systems and related soil fauna may be promoted for enhancement of biological activity and productivity
of pastureland in desert. The strategy may be adopted for developing a sustainable pedoecosystem in a region of the world
where agriculture is notoriously difficult. 相似文献
588.
摘要企业社会责任是指企业在创造利润、对股东利益负责的同时,还应承担对员工、社会和环境的责任,包括遵守商业道德、生产安全、职业健康、保护消费者合法权益、节约资源等.企业承担社会责任是企业为生存而适应制度环境变迁的产物.伴随着制度环境变迁,西方企业社会责任的发展经历了无意识期、启蒙期和成熟期三个阶段.建国以来,中国企业的制度环境经历计划经济体制和向市场经济体制转型时期,均出现了企业承担社会责任功能的“失范”,即计划经济时期的“企业办社会”和向市场经济转型时期下的凸显“经济人本性”.当前,企韭利益与社会利益矛盾的凸显和社会公平公正期望的提升,使企业社会责任问题在中国变得日益紧迫、上下关注.党发出了“科学发展”的号召.科学发展这一制度环境,是对中国企韭承担社会责任的期待.而中国企业社会责任的实现,则亟待制度化建设保证,即要求企业产权制度明晰化,企业社会责任法制化,企业社会责任评价体系科学化,企业社会责任信息披露制度化,企业社会责任监督主体多元化. 相似文献
589.
590.