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991.
992.
<正>阿布扎比正在建设世界上第一个零碳城市,这将是一个没有汽车和摩天大楼,完全采用太阳能作为能源的城市。海湾国家阿联酋盛产石油,阿布扎比是其中最大的酋长国,拥有阿 相似文献
993.
大亚湾大鹏澳海域C、N、BSi的沉积记录研究 总被引:3,自引:0,他引:3
研究了大亚湾大鹏澳海域鱼类养殖区、贝类养殖区以及核电站附近3个站位50~78 cm的柱状沉积物中生物硅(BSi)、总有机碳(TOC)、总氮(TN)等生源要素的垂直变化,以揭示人类活动对海洋环境影响的沉积记录。位于近岸海水养殖区的两个沉积柱中,近年来TOC含量呈明显上升趋势,而核电站附近海域略有下降。从TOC/TN比值判断(三个沉积柱平均分别为9.54、7.42、7.9),该海域TOC是陆源和水生两种来源的混合物。此外,养殖区上表层沉积物中水生有机碳(TOCa)含量呈明显下降趋势,而TOC/TN比值则上升,说明养殖区水生初级生产力及其对总初级生产力的贡献下降;相反,陆源污染所造成的陆源有机碳(TOCt)含量明显增加。在核电站附近海域,TOCa含量明显上升,TOC/TN和TOCt值下降,表明核电站的运行使水体初级生产力上升,陆源有机碳输入则减少。BSi、BSi/TOCa的垂直分布表明,海水养殖区硅藻对总初级生产力的贡献逐年上升,而核电站海域硅藻的贡献则下降。 相似文献
994.
995.
NPP增长驱动下的中国森林生态系统碳汇 总被引:8,自引:1,他引:7
森林生态系统能够有效地吸收大气中的CO2,在一定程度上缓解全球变暖的压力。生态系统固碳能力取决于两个关键因素:NPP的增长强度与碳周转时间。本文通过对遥感监测到的森林生态系统NPP增长趋势进行校正,结合森林样地实测数据得到的碳分配系数与周转时间,建立了中国森林生态系统碳周转模型,并模拟了1982~1999年森林生态系统的碳汇量及其年际变化。结果表明:1982~1999年,我国森林生态系统的平均碳汇量为0.051 PgC a-1,其中植被的碳汇量为0.034 PgC a-1,凋落物的碳汇量为0.013 PgC a-1,土壤的碳汇量为0.004PgC a-1;不同森林类型中,常绿针叶林和常绿阔叶林的碳汇贡献最大,落叶针叶林和针阔叶混交林贡献最小;进一步分析表明森林植被的固碳效率显著地受到碳周转时间的控制。 相似文献
996.
Potential toxic risk of heavy metals from sediment of the Pearl River
in South China 总被引:4,自引:1,他引:3
Based on the monitoring of five heavy metal elements in the surface sediments of the Pearl River in South China, potential toxicity of the heavy metals was assessed using consensus-based sediment quality guidelines (SQGs) method and geo-accumulation (Igeo) index method. The monitoring results showed the heavy metal concentrations were significantly and positively correlated with each other, demonstrating a common trend in variation of concentration in the surface sediments. The assessment using the consensus-based SQGs method showed the potential toxicity of Cu was the highest, and Cd was the lowest. The evaluation based on mean probable effect concentration (PEC) quotient showed the region was seriously polluted with high toxicity heavy metals. Correlation analysis revealed a significant and positive correlation between the mean PEC quotient and the average of Igeo with a correlation coefficient of 0.926 (n = 23, P < 0.01). In conclusion, the consensus-based SQGs and mean PEC quotient are applicable to assess potential toxicity risks of heavy metals in freshwater sediments in the Pearl River. 相似文献
997.
CHEN Bing KITAGAWA Hiroyuki HU Ke JIE Dongmei YANG Junpeng LI Jingmin 《环境科学学报(英文版)》2009,21(10):1363-1370
Recent observations of Asian dust storms show an eastern expansion of the source area to degraded lands, where dust emissions have been little studied. The dust concentrations over the saline land of the western Songnen Plain (SSL), Northeastern China, are circumstantially higher than those from the northwestern Chinese deserts. These concentrations are sensitive to the surface soil conditions and wind velocity on the ground. The dust samples collected during dust storm events on the SSL contain abundant Na, Mg, Al, K, Ca, Fe and Ti, as well as toxic elements such as Cu, V, Zn and Ba. Individual particle analysis reveals that fine saline particles (< 10 μm in diameter) on the saline land, consisting largely of carbonate, halite and sulfate together with lithogenic minerals such as SiO2 and aluminosilicate, are eventually uplifted during the interval from spring to autumn. The predominantly fine saline particles uplifted from the SSL are likely transported eastward by the winter monsoon circulation and westerlies. Recent degradation of saline lands in Northeastern China would not only increase the frequency of dust storm events in the downwind area, but also might change the chemical composition of the Asian dust emissions. 相似文献
998.
Tree species composition was important for carbon storage within the same climate range.To quantify the dynamics of ecosystem carbon allocation as affected by different tree species,we measured the above- and belowground biomass accumulation in 22 years,as well as the tissue carbon concentrations of trees in Cunninghamia lanceolata plantation and Michelia macclurei plantation.Results indicated that M.macclurei plantation stored significantly more carbon (174.8 tons/hm2) than C.lanceolata plantation (154.3 tons/hm2).Most of the carbon was found in the soil pool (57.1% in M.macclurei plantation,55.2% in C.lanceolata plantation).Tree and soil component of M.macclurei plantation possessed significantly higher carbon storage than that of the C.lanceolata plantation (p<0.05).No significant difference was found in the carbon storage of understory and forest floor.These results suggest that the broadleaved species (M.macclurei) possesses greater carbon sequestration potential than the coniferous species (C.lanceolata) in southern China. 相似文献
999.
当前,低碳经济已成世界经济新趋势,发展低碳经济是中国实现经济发展方式转变的重要契机。当然,认同低碳经济并不等于认同美方的碳关税。中国应在碳关税问题的利益博弈和权衡中有所作为,主动采取相应措施,与其他发展中国家结成“反碳关税联盟”以争取国际舆论,共同反对美国对进口产品征收碳关税的企图。 相似文献
1000.