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通过暴露和暴露恢复试验研究低浓度稀土元素镧对小麦幼苗营养生长的影响.结果表明,幼苗暴露于0.5~25mg/L镧溶液,镧抑制幼苗根的伸长,降低茎叶和根系的干重,降低矿质元素Ca、Mg、Zn、Mn的含量;镧的植物富集速度及镧从根系向茎叶迁移速度与镧暴露浓度呈明显的对数关系.去除镧后,幼苗生长加快,生物量及根长增加,矿质元素含量升高,但已富集的镧主要在作物体内再分配,很难排出体外,且随作物的生长而逐步的稀释,但仍影响作物生长.幼苗中镧的富集量与幼苗相对干重呈负线性相关,幼苗根系生长比茎叶更容易受到溶液中镧抑制. 相似文献
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在全球范围内为应对气候变化而达成二氧化碳减排共识的背景下,探求“经济增长”与“二氧化碳排放”间相互关系.运用协整,向量自回归模型,脉冲响应函数以及格兰杰因果检验等方法,对处在经济发展不同阶段区域的人均二氧化碳排放量与经济增长间关系进行因果检验.研究结果表明:区域经济发展与人均二氧化碳排放量存在长期均衡关系,但是由于区域间经济发展水平及发展方式的不同,人均二氧化碳排放量与经济增长间相互影响程度存在差异,且二氧化碳排放量的减少并不是经济增长的必然结果,必须通过产业结构调整,扶持第三产业,使用清洁能源,发展低碳经济的方式来实现,本文对我国碳减排政策的制定具有一定借鉴意义. 相似文献
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Marta Staniszewsk Iga Koniecko Lucyna Falkowsk Dorota Bursk Joanna Kie?czewska 《环境科学学报(英文版)》2016,28(3):24-32
This study was derived from field investigations to assess bisphenol A (BPA) concentrations in the sea and river sediments of the Gulf of Gdansk. Black carbon (BC) and total organic carbon (TOC) were identified as influencing factors on the accumulation. As a result of the transportation of BC with organic matter via rivers into the Gulf of Gdansk, the highest mean concentrations (11.26 ng BPA/(g dry weight (dw))), were determined in the sediments of river estuaries. Sediments in coastal stations were characterized by the lowest mean concentrations (5.73 ng BPA/(g dw)). TOC content below 0.1% determined the sorption of BPA on BC particles in sediments, and statistically significant correlation between the concentration of BPA and the BC/TOC ratio was found in these cases. In addition, dependency between the concentration of BPA and the content of BC was discovered in sediments where the BC/TOC ratio was > 0.33. 相似文献
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Analysis of relationship between economic growth and environment in Benxi Shiqiaozi Development Zone
AnalysisofrelationshipbetweeneconomicgrowthandenvironmentinBenxiShiqiaoziDevelopmentZone¥LiBin;RuJiang;YeWenhu;XuYunlin(Cente... 相似文献
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基于1992~2006年中国经济发展和环境污染事故时序数据,建立了中国经济发展和环境污染事故发生的计量模型,以此来分析中国环境安全状态的发展阶段与趋势.结果表明,中国环境污染事故频数与经济增长之间呈现倒“N”型波浪式的EKC特征.环境污染事故频数、水污染事故频数、大气污染事故频数随着人均GDP的快速提高, 先下降、后上升、再下降, 但还会出现反复.环境污染事故的发生不同于环境污染物的排放,不是经济发展过程中的必然产物,但是却具有非常大的不确定性和危害性,必须利用先进的政策、制度和技术,才可以有效减少污染事故的发生. 相似文献
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The Science of Nature - 相似文献
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铬胁迫对3种草本植物生长及铬积累的影响 总被引:6,自引:2,他引:6
为了阐明铬胁迫对白花三叶草(Trifolium repens)、高羊茅(Festuca arundinacea)、紫花苜蓿(Medicago sativa)3种草本植物的毒害机制,为铬污染土壤植物修复提供理论依据,采用盆栽试验,在土壤中添加不同浓度的铬[Cr(Ⅵ)](K2Cr2O7为0、100、200、300和400 mg.kg-1),研究重金属铬对3种草本植物生长、生理特性、重金属铬累积与分布的影响.结果表明,白花三叶草、高羊茅和紫花苜蓿的平均耐性指数分别为62.5、48.3和36.33.在铬浓度为400 mg.kg-1处理条件下,白花三叶草和高羊茅叶绿素含量、SOD和POD活性分别为对照的57.14%、51.51%、35.76%和63.27%、52.96%、41.36%,而紫花苜蓿无法生存.在铬胁迫下,3种草本植物的株高、根长、地上(下)部干重均表现降低,其降低大小顺序为紫花苜蓿〉高羊茅〉白花三叶草,但MDA含量增加,并且紫花苜蓿增加幅度最大,高羊茅次之,白花三叶草最小.三者对铬的耐受性表现为白花三叶草〉高羊茅〉紫花苜蓿.3种草本植物叶片积累的铬主要贮存于细胞壁,其次是细胞质,而在叶绿体和线粒体中含量较低.叶绿体和线粒体中铬含量与叶绿素、MDA含量、SOD和POD活性存在明显的相关性.随着铬浓度增加,3种草本植物叶片亚细胞组分中铬含量增加,并且总是紫花苜蓿〉高羊茅〉白花三叶草.当铬处理浓度为300 mg.kg-1时,与白花三叶草、高羊茅相比,紫花苜蓿叶片富集铬浓度最高,达51.44 mg.kg-1,其中分配于叶绿体(19.09%)和线粒体(18.04%)中铬的比例也明显较高.白花三叶草、高羊茅和紫花苜蓿地上部和地下部富集系数平均值分别为1.22、1.54;1.16、1.44和1.26、1.62,转运系数平均值分别为0.78、0.78和0.74.在重金属铬污染土壤治理中,白花三叶草和高羊茅有一定的潜在应用价值. 相似文献
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Bourdon E 《Die Naturwissenschaften》2005,92(12):586-591
The phylogenetic affinities of the extinct pseudo-toothed birds have remained controversial. Some authors noted that they
resemble both pelicans and allies (Pelecaniformes) and tube-nosed birds (Procellariiformes), but assigned them to a distinct
taxon, the Odontopterygiformes. In most recent studies, the pseudo-toothed birds are referred to the family Pelagornithidae
inside the Pelecaniformes. Here, I perform a cladistic analysis with five taxa of the pseudo-toothed birds including two undescribed
new species from the Early Tertiary of Morocco. The present hypothesis strongly supports a sister group relationship of pseudo-toothed
birds (Odontopterygiformes) and waterfowls (Anseriformes). The Odontoanserae (Odontopterygiformes plus Anseriformes) are the
sister group of Neoaves. The placement of the landfowls (Galliformes) as the sister taxon of all other neognathous birds does
not support the consensus view that the Galloanserae (Galliformes plus Anseriformes) are monophyletic.
Electronic supplementary material Supplementary material is available in the online version of this article at .
Communicated by G. Mayr 相似文献
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Interactions of zinc and cadmium toxicity in their effects on growth and in antioxidative systems in tomato plants (Solanum lycopersicum) 总被引:1,自引:0,他引:1
The interaction between zinc and cadmium was investigated in tomato plants (Solanum lycopersicum). Ten-day-old seedlings were treated with 10 μmol/L CDC12 associated to different concentrations of ZnC12 (10, 50, 100, and 150 μmol/L). Zn supply clearly reduced Cd accumulation in leaves and simultaneously increased Zn concentration. Cd induced oxidative stress in leaves as indicated by an increase in thiobarbituric acid-reactive substances (TBARS) level and chlorophyll breakdown. Furthermore, compared with control, Cdtreate plants had significantly higher activities of superoxide dismutase (SOD, EC 1.15.1.1), whereas, catalase (CAT, EC 1.111.1.6),ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2) activities were significantly suppressed by Cd addition. Zn supplementation, at low level, restored and enhanced the functional activity of these enzymes (SOD, CAT, APX and GR) as compared to Cd-alone-treated plants. The beneficial effect of adequate Zn level on Cd toxicity was confirmed by a significant decrease in TBARS level and restoration of chlorophyll content. However, when Zn was added at high level in combination with Cd there was an accumulation of oxidative stress, which was higher than that for Cd or excess Zn alone treatments. These results suggested that higher Zn concentrations and Cd are synergistic in their effect on plant growth parameters and oxidative stress. 相似文献
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Interactions of zinc and cadmium toxicity in their effects on growth and in antioxidative systems in tomato plants (Solanum lycopersicum) 总被引:2,自引:0,他引:2
The interaction between zinc and cadmium was investigated in tomato plants (Solanum lycopersicum). Ten-day-old seedlings were
treated with 10 mol/L CdCl2 associated to di erent concentrations of ZnCl2 (10, 50, 100, and 150 mol/L). Zn supply clearly reduced
Cd accumulation in leaves and simultaneously increased Zn concentration. Cd induced oxidative stress in leaves as indicated by an
increase in thiobarbituric acid-reactive substances (TBARS) level and chlorophyll breakdown. Furthermore, compared with control, Cdtreated
plants had significantly higher activities of superoxide dismutase (SOD, EC 1.15.1.1), whereas, catalase (CAT, EC 1.111.1.6),
ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2) activities were significantly suppressed by Cd
addition. Zn supplementation, at low level, restored and enhanced the functional activity of these enzymes (SOD, CAT, APX and GR) as
compared to Cd-alone-treated plants. The beneficial e ect of adequate Zn level on Cd toxicity was confirmed by a significant decrease
in TBARS level and restoration of chlorophyll content. However, when Zn was added at high level in combination with Cd there was an
accumulation of oxidative stress, which was higher than that for Cd or excess Zn alone treatments. These results suggested that higher
Zn concentrations and Cd are synergistic in their e ect on plant growth parameters and oxidative stress. 相似文献
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于2005年4~12月对武汉东湖落雁岛和关桥2个池塘进行综合调查,考察浮游病毒丰度和叶绿素a含量的变化,以及水温、pH值、溶解氧量、总氮和总磷等环境因子的变化,分析浮游病毒与浮游植物、环境因子之间的相互关系.结果表明,在营养水平较高的水体中,浮游病毒丰度相应较高,但与营养物浓度变化无显著的相关性.2个采样点浮游病毒的平均丰度分别为2.99×108,4.24×108VLPs/mL(峰值出现在9、10月份).叶绿素a浓度的平均值分别为96.66,166.74μg/L.关桥采样点的浮游病毒丰度与前一个月的叶绿素a浓度呈显著相关(r=0.809,P<0.01),其显著性水平高于与当月叶绿素a浓度的相关性(r=0.634,P<0.05),而浮游病毒丰度与后一个月的叶绿素a浓度不呈显著相关(P>0.05). 相似文献
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本文选取沿海地区工业废水直排入海量、工业废水中化学需氧量入海量、工业废水中氨氮入海量以及赤潮发生面积作为海洋环境压力指标,基于Tapio脱钩模型,引入脱钩指数构建脱钩状态评价指标,从时间和空间两个层面探讨我国海洋经济增长和海洋环境压力的脱钩状态演变趋势。结果表明:2002~2010年,各项海洋环境压力指标与我国海洋经济增长之间均呈现出扩张负脱钩、弱脱钩和强脱钩三种状态,但演变趋势各有不同;空间上,环渤海经济区海洋环境压力脱钩状态总体表现最优,各项污染指标基本稳定在弱脱钩和强脱钩状态;长三角经济区和珠三角经济区的脱钩状态总体波动较大,各项污染指标在多个不同时期出现恶化情形。基于以上研究结果,本文提出了相应的对策建议,以期实现海洋经济和海洋环境压力的完全脱钩。 相似文献
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《Atmospheric Environment. Part A. General Topics》1992,26(4):725-730
Ozone and regional tracers are directly related at a rural Rhode Island site during summer. Unlike elemental tracers and sulfate, ozone has a significant background which appears to be unrelated to regional-pollution sources. Summer ozone concentrations were apportioned among northeastern and midwestern sources using results from regional-scale receptor modeling of pollution aerosol. The Northeast contributed roughly 40% more than the Midwest, but ‘background’ accounted for up to half of the average ozone concentration. 相似文献