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871.
氮素输入影响下淡水湿地碳过程变化 总被引:12,自引:0,他引:12
通过野外控制试验和室内培养试验研究了氮素输入对淡水沼泽湿地碳循环过程的影响。结果表明,氮素的输入能够提高沼泽湿地碳的生物累积,但过多的氮素输入则引起植物生产力的降低,并对常年积水沼泽湿地有机物质的分解有抑制作用。在非淹水条件下,氮素输入后有机物质的分解速率明显大于淹水条件,说明水文条件和氮素输入对枯落物的分解过程都有重要的影响,只是在不同环境条件下的响应存在一定的差异。氮素输入后,植物—土壤系统CO2排放量增大;但是,过多氮素输入后植物—土壤系统呼吸速率降低,这说明一定量的氮素输入可促进植物的生长和根的发育,对微生物的活性也有一定的影响,但过多的氮素输入则会对这些过程产生一定的抑制作用。氮素输入对土壤溶解有机碳(DOC)有明显的影响。氮素输入后,根层土壤DOC含量明显降低(P<0.05),不同土壤深度DOC的变化有一定的差异。 相似文献
872.
LIU Xinfan NI Shijun LU Qiuxi JIN Jingfu ZHU Laimin . Open Lab of Ore Deposits Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang . Chengdu Institute of Technology Chengdu Liu Xinzhu 《《地质学报》英文版》1999,73(1):30-39
This paper deals with characteristics of silicon isotope compositions and siliceous cathodolumines-cence of host rocks, ores and hydrothermal silicified quartz of the Carlin-type ore deposits in the Yunnan-Guizhou-Guangxi triangle area. The study shows that primary silicified quartz is nonluminescent but quartz in host rocks andsecondary silicified quartz are luminescent by the action of cathode rays. Correspondingly, silicon isotope composi-tions of host rocks, ores and hydrothermal quartz veins are clearly distinguished. In strata from the Middle Triassic tothe "Dachang" host bed, δ~(30)Si of the host rocks ranges from 0.0‰-0.3‰, while that of primary ore-forming silici-fied fluids from -0.1‰ to -0.4‰, in the Upper Permian and Lower Carboniferous strata and Indosinian diabasehost beds, δ~(30)Si of the host rocks is from -0.1‰ to -0.2‰ and that of the primary silicified quartz veins from 0.3‰-0.5‰. This pattern demonstrates the following geochemical mineralization process: primary ore-forming sili-ceous fluids migrated upwards quickly along the main passages of deep-seated faults from mantle to crust and en-tered secondary faults where gold deposits were eventually formed as a result of permeation and replacement of thesiliceous ore-forming fluids into different ore-bearing strata. This gives important evidence for the fact that ore-forming fluids of this type of gold deposits were mainly derived from upper mantle differentiation and shows goodprospects for deep gold deposits and geochemical background for large and superlarge gold deposits. 相似文献
873.
四川康定温泉系统深源CO2释放研究 总被引:1,自引:1,他引:1
根据水化学分析和稳定碳同位素的测试数据,本文计算了四川康定温泉热水和热储的CO2含量和深源CO2的释放量,探讨了热水中CO2的成因。温泉热水中CO2含量最高为1840.16mg/L,平均为1060.53mg/L,属于富含深源CO2的温泉系统。热水和CO2气的碳同位素揭示深源CO2的成因为幔源和碳酸盐岩变质脱气以及两者的混合。康定12个温泉深源CO2的排出量为1766.43t/a,其中至少40%呈气 相似文献
874.
本文利用2006年夏季大气边界层观测资料,采用涡动相关法分析了我国西北地区戈壁下垫面碳收支及水热循环的规律和特征,并分析了大气湍流特征.结果表明:夏季白天的CO2湍流通量呈逆输送特征,即CO2白天向下输送,夜间向上输送,平均数值为-0.199 mg·m-2·s-1,整体上表现为碳汇;戈壁地区湿度小,其数值受水平来流的影响较大,日变化特征不明显;温度的归一化标准差与稳定度参数的关系满足Monin-Obukhov Similarity (MOS)理论;温度和CO2的能谱相似;互谱uc与uθ,wc与wθ相似;水汽和CO2的输送主要受水平方向湍流的影响. 相似文献
875.
为揭示巢湖水体二氧化碳浓度(cCO2)时空变化特征及其影响因素,2017年2、4、8和11月分别采集巢湖表层水样,测定水样的理化、生物学参数以及cCO2,并以此计算其水-气界面交换通量.结果表明:巢湖表层水体cCO2的变化范围为13.31~55.47 μmol/L,年平均值为26.27 μmol/L,在空间上呈现出西高东低的分布趋势;在季节上表现为暖季(夏季)低、冷季(春、秋和冬季)高的规律.巢湖表层水体cCO2与溶解性有机碳浓度呈显著正相关,与叶绿素a浓度呈显著负相关,说明有机质分解和光合作用在巢湖CO2生物化学循环过程中占重要作用;同时,南淝河等入湖河流污染严重,输入大量有机和无机碳,对西巢湖水体CO2贡献较大.总体上,巢湖CO2排放量相对较低,巢湖部分区域在冷季(2、11月)表现为CO2的汇.本研究对于明晰富营养化湖泊CO2排放特征以及准确估算全球内陆湖泊碳通量等都具有参考价值. 相似文献
876.
湖库淡水水域对温室气体排放的贡献不容小觑,然而观测时间的代表性不足以及缺乏对降雨因素的考虑制约了碳排放的准确估计.本研究以湖北宜昌境内官庄水库为例,选取强降雨多发的夏季时段,针对水气界面温室气体通量、水体表层和垂向剖面气体溶存浓度及环境因子开展了为期1周的原位高频观测,以探讨夏季降雨事件对水库温室气体通量变化的影响.结果表明,观测期内官庄水库水气界面CH4通量变化范围为0.007~0.077 mg/(m2·h),CO2通量范围为5.48~57.57 mg/(m2·h),白天和夜晚均表现为大气的碳源.小雨、中雨乃至暴雨天气条件下,CH4和CO2日均通量均较低,日通量倾向于受风速和温度调控.CH4和CO2通量变化趋势较为一致,观测期内日间排放量高于夜间排放量出现的次数更多,昼夜差异对降雨天气状况无明显响应,风速是CH4和CO2通量昼夜变化的主导因素.暴雨过程中,CH4-k600和CO2-k600与水气温差存在显著正相关,但水体垂向混合过程十分短暂.在平均雨强为3.8 mm/h的暴雨第I阶段,CH4-k600对风速和降雨的响应明显,而在雨强更大(8.5 mm/h)的第II阶段,CH4-k600与风速、降雨均未表现出相关性,通量箱在强降雨条件下的适用性可能存在雨强阈值. 相似文献
877.
使用HadCM3L气候模式,针对突然增加的4倍CO2浓度和增加4%的太阳辐射强迫进行一系列理想化模拟试验,分析并比较了CO2强迫和太阳辐射强迫对气候系统的影响机制和异同。模拟结果表明,突然增加的4倍CO2浓度和增加4%的太阳辐射造成的长期全球表面平均温度变化基本相同,但二者造成降水的变化差异很大。气候系统对CO2和太阳辐射的响应可以分为快响应和慢响应两个部分,而降水的差异主要体现在大约1个月时间尺度内的快响应阶段,在这一时间段,陆地区域CO2的气孔效应减少了植被的蒸腾作用,导致降水受到抑制;海洋区域CO2的辐射效应会首先导致大气长波吸收增强,而海洋的比热较大,所以海表温度变化落后于低层大气,低层大气的垂直稳定度增加,海表向上蒸发受到抑制。此外,比较不同时间尺度上CO2对气候系统的影响,可以发现在1个月的短时间尺度上,对陆地而言,CO2的气孔效应对气候系统的影响占主导地位,但在数年以上更长的时间尺度上,CO2的辐射效应是导致地气系统温度升高的主要原因。 相似文献
878.
There is a rich empirical literature testing whether per capita carbon dioxide emissions tend to converge over time and across countries. This article provides a meta-analysis of the results from this research, and discusses how carbon emissions convergence may be understood in, for instance, the presence of international knowledge spillovers and policy convergence. The results display evidence of either divergence or persistent gaps at the global level, but convergence of per capita carbon dioxide emissions between richer industrialized countries. However, the results appear sensitive to the choice of data sample and choice of convergence concept, e.g. stochastic convergence versus β-convergence. Moreover, peer-reviewed studies have a higher likelihood of reporting convergence in carbon dioxide emissions compared to non-refereed work.
POLICY RELEVANCE
The empirical basis for an egalitarian rule of equal emissions per capita in the design of global climate agreements is not solid; this supports the need to move beyond single allocation rules, and increase knowledge about the impacts of combined scenarios. However, even in the context of the 2015 Paris Agreement with its emphasis on voluntary contributions and ‘national circumstances’, different equity-based principles could serve as useful points of reference for how the remaining carbon budget should be allocated. 相似文献
879.
M. L. Thompson I. G. Enting G. I. Pearman P. Hyson 《Journal of Atmospheric Chemistry》1986,4(1):125-155
A method is described for the analysis of the interannual variability of background atmospheric carbon dioxide concentration. The analysis is carried out on the data from 6 observatories for which records of >8 years were available.A global-scale interannual variation of CO2 concentration in the troposphere with a characteristic time-scale of 2–3 years has been confirmed throughout the period of the records. These variations are estimated to be associated with carbon cycle imbalances of 2–3 Gt or annual net exchanges between the atmosphere and another carbon reservoir(s) at a rate of about 1.2 Gt of carbon per year. Lag correlations and amplitude comparisons between the records suggests a low latitude southern hemisphere origin to this phenomenon.The interannual variations of CO2 increase are found to be correlated with those observed in data for Pacific sea surface temperatures and Pacific witd stress, the Southern Oscillation Index and the Quasi-Biennial Oscillation. However multiple regression studies found that once the Southern Oscillation index is used as an explanatory variable for CO2 variations, the inclusion of additional geophysical variables does not give any significant improvement in the regression. 相似文献
880.
Gerhard?LammelEmail author Thomas?Engelhardt Adrian?Leip Christian?Neusü? Andreas?R?hrl Birgit?Wehner Alfred?Wiedensohler Paul?Wieser 《Journal of Atmospheric Chemistry》2005,51(1):95-117
The change of the chemical composition of the near-ground level atmospheric aerosol was studied during two summer episodes by a Lagrangian type of experimental approach. Bulk and single-particle chemical analyses of ions and elements in the particulate phase were deployed. N(-III) and N(V) components were also measured in the gas-phase. The measurements were completed by particle size distributions.Secondary inorganic aerosols (SIA) and fine particles of ≈0.2–0.4 μm size were still elevated 50 km downwind of the city. The direct comparison of transport over the city in contrast to transport over the surrounding areas showed that SIA was formed from emission from the city within less than 3 h. Relative increases, i.e., enrichment during transport were observed for primary and secondary aerosol components. The degree of mixing on the individual particle level increased significantly during transport in the area. In particular, newly emitted carbonaceous particles became internally mixed within hours with pre-existing sulphate particles. Mostly due to secondary aerosol formation the average particle size (mass median diameter) of major constituents of the aerosol was significantly decreased while being transported over 13 h. Given recent insights which link fine particles number and mass concentrations with health risks, the results suggest that rural populations in areas which frequently are located within an urban plume might run an elevated health risk relative to populations in areas not affected by urban plumes. 相似文献